/*
 *   This file is provided under a GPLv2 license.  When using or
 *   redistributing this file, you may do so under that license.
 *
 *   GPL LICENSE SUMMARY
 *
 *   Copyright (C) 2016-2018 T-Platforms JSC All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or modify it
 *   under the terms and conditions of the GNU General Public License,
 *   version 2, as published by the Free Software Foundation.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
 *   Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License along
 *   with this program; if not, one can be found http://www.gnu.org/licenses/.
 *
 *   The full GNU General Public License is included in this distribution in
 *   the file called "COPYING".
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * IDT PCIe-switch NTB Linux driver
 *
 * Contact Information:
 * Serge Semin <fancer.lancer@gmail.com>, <Sergey.Semin@t-platforms.ru>
 */

#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/sizes.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/aer.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/debugfs.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/ntb.h>

#include "ntb_hw_idt.h"

#define NTB_NAME        "ntb_hw_idt"
#define NTB_DESC        "IDT PCI-E Non-Transparent Bridge Driver"
#define NTB_VER         "2.0"
#define NTB_IRQNAME     "ntb_irq_idt"

MODULE_DESCRIPTION(NTB_DESC);
MODULE_VERSION(NTB_VER);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("T-platforms");

/*
 * NT Endpoint registers table simplifying a loop access to the functionally
 * related registers
 */
static const struct idt_ntb_regs ntdata_tbl = {
        { {IDT_NT_BARSETUP0,    IDT_NT_BARLIMIT0,
           IDT_NT_BARLTBASE0,   IDT_NT_BARUTBASE0},
          {IDT_NT_BARSETUP1,    IDT_NT_BARLIMIT1,
           IDT_NT_BARLTBASE1,   IDT_NT_BARUTBASE1},
          {IDT_NT_BARSETUP2,    IDT_NT_BARLIMIT2,
           IDT_NT_BARLTBASE2,   IDT_NT_BARUTBASE2},
          {IDT_NT_BARSETUP3,    IDT_NT_BARLIMIT3,
           IDT_NT_BARLTBASE3,   IDT_NT_BARUTBASE3},
          {IDT_NT_BARSETUP4,    IDT_NT_BARLIMIT4,
           IDT_NT_BARLTBASE4,   IDT_NT_BARUTBASE4},
          {IDT_NT_BARSETUP5,    IDT_NT_BARLIMIT5,
           IDT_NT_BARLTBASE5,   IDT_NT_BARUTBASE5} },
        { {IDT_NT_INMSG0,       IDT_NT_OUTMSG0, IDT_NT_INMSGSRC0},
          {IDT_NT_INMSG1,       IDT_NT_OUTMSG1, IDT_NT_INMSGSRC1},
          {IDT_NT_INMSG2,       IDT_NT_OUTMSG2, IDT_NT_INMSGSRC2},
          {IDT_NT_INMSG3,       IDT_NT_OUTMSG3, IDT_NT_INMSGSRC3} }
};

/*
 * NT Endpoint ports data table with the corresponding pcie command, link
 * status, control and BAR-related registers
 */
static const struct idt_ntb_port portdata_tbl[IDT_MAX_NR_PORTS] = {
/*0*/   { IDT_SW_NTP0_PCIECMDSTS,       IDT_SW_NTP0_PCIELCTLSTS,
          IDT_SW_NTP0_NTCTL,
          IDT_SW_SWPORT0CTL,            IDT_SW_SWPORT0STS,
          { {IDT_SW_NTP0_BARSETUP0,     IDT_SW_NTP0_BARLIMIT0,
             IDT_SW_NTP0_BARLTBASE0,    IDT_SW_NTP0_BARUTBASE0},
            {IDT_SW_NTP0_BARSETUP1,     IDT_SW_NTP0_BARLIMIT1,
             IDT_SW_NTP0_BARLTBASE1,    IDT_SW_NTP0_BARUTBASE1},
            {IDT_SW_NTP0_BARSETUP2,     IDT_SW_NTP0_BARLIMIT2,
             IDT_SW_NTP0_BARLTBASE2,    IDT_SW_NTP0_BARUTBASE2},
            {IDT_SW_NTP0_BARSETUP3,     IDT_SW_NTP0_BARLIMIT3,
             IDT_SW_NTP0_BARLTBASE3,    IDT_SW_NTP0_BARUTBASE3},
            {IDT_SW_NTP0_BARSETUP4,     IDT_SW_NTP0_BARLIMIT4,
             IDT_SW_NTP0_BARLTBASE4,    IDT_SW_NTP0_BARUTBASE4},
            {IDT_SW_NTP0_BARSETUP5,     IDT_SW_NTP0_BARLIMIT5,
             IDT_SW_NTP0_BARLTBASE5,    IDT_SW_NTP0_BARUTBASE5} } },
/*1*/   {0},
/*2*/   { IDT_SW_NTP2_PCIECMDSTS,       IDT_SW_NTP2_PCIELCTLSTS,
          IDT_SW_NTP2_NTCTL,
          IDT_SW_SWPORT2CTL,            IDT_SW_SWPORT2STS,
          { {IDT_SW_NTP2_BARSETUP0,     IDT_SW_NTP2_BARLIMIT0,
             IDT_SW_NTP2_BARLTBASE0,    IDT_SW_NTP2_BARUTBASE0},
            {IDT_SW_NTP2_BARSETUP1,     IDT_SW_NTP2_BARLIMIT1,
             IDT_SW_NTP2_BARLTBASE1,    IDT_SW_NTP2_BARUTBASE1},
            {IDT_SW_NTP2_BARSETUP2,     IDT_SW_NTP2_BARLIMIT2,
             IDT_SW_NTP2_BARLTBASE2,    IDT_SW_NTP2_BARUTBASE2},
            {IDT_SW_NTP2_BARSETUP3,     IDT_SW_NTP2_BARLIMIT3,
             IDT_SW_NTP2_BARLTBASE3,    IDT_SW_NTP2_BARUTBASE3},
            {IDT_SW_NTP2_BARSETUP4,     IDT_SW_NTP2_BARLIMIT4,
             IDT_SW_NTP2_BARLTBASE4,    IDT_SW_NTP2_BARUTBASE4},
            {IDT_SW_NTP2_BARSETUP5,     IDT_SW_NTP2_BARLIMIT5,
             IDT_SW_NTP2_BARLTBASE5,    IDT_SW_NTP2_BARUTBASE5} } },
/*3*/   {0},
/*4*/   { IDT_SW_NTP4_PCIECMDSTS,       IDT_SW_NTP4_PCIELCTLSTS,
          IDT_SW_NTP4_NTCTL,
          IDT_SW_SWPORT4CTL,            IDT_SW_SWPORT4STS,
          { {IDT_SW_NTP4_BARSETUP0,     IDT_SW_NTP4_BARLIMIT0,
             IDT_SW_NTP4_BARLTBASE0,    IDT_SW_NTP4_BARUTBASE0},
            {IDT_SW_NTP4_BARSETUP1,     IDT_SW_NTP4_BARLIMIT1,
             IDT_SW_NTP4_BARLTBASE1,    IDT_SW_NTP4_BARUTBASE1},
            {IDT_SW_NTP4_BARSETUP2,     IDT_SW_NTP4_BARLIMIT2,
             IDT_SW_NTP4_BARLTBASE2,    IDT_SW_NTP4_BARUTBASE2},
            {IDT_SW_NTP4_BARSETUP3,     IDT_SW_NTP4_BARLIMIT3,
             IDT_SW_NTP4_BARLTBASE3,    IDT_SW_NTP4_BARUTBASE3},
            {IDT_SW_NTP4_BARSETUP4,     IDT_SW_NTP4_BARLIMIT4,
             IDT_SW_NTP4_BARLTBASE4,    IDT_SW_NTP4_BARUTBASE4},
            {IDT_SW_NTP4_BARSETUP5,     IDT_SW_NTP4_BARLIMIT5,
             IDT_SW_NTP4_BARLTBASE5,    IDT_SW_NTP4_BARUTBASE5} } },
/*5*/   {0},
/*6*/   { IDT_SW_NTP6_PCIECMDSTS,       IDT_SW_NTP6_PCIELCTLSTS,
          IDT_SW_NTP6_NTCTL,
          IDT_SW_SWPORT6CTL,            IDT_SW_SWPORT6STS,
          { {IDT_SW_NTP6_BARSETUP0,     IDT_SW_NTP6_BARLIMIT0,
             IDT_SW_NTP6_BARLTBASE0,    IDT_SW_NTP6_BARUTBASE0},
            {IDT_SW_NTP6_BARSETUP1,     IDT_SW_NTP6_BARLIMIT1,
             IDT_SW_NTP6_BARLTBASE1,    IDT_SW_NTP6_BARUTBASE1},
            {IDT_SW_NTP6_BARSETUP2,     IDT_SW_NTP6_BARLIMIT2,
             IDT_SW_NTP6_BARLTBASE2,    IDT_SW_NTP6_BARUTBASE2},
            {IDT_SW_NTP6_BARSETUP3,     IDT_SW_NTP6_BARLIMIT3,
             IDT_SW_NTP6_BARLTBASE3,    IDT_SW_NTP6_BARUTBASE3},
            {IDT_SW_NTP6_BARSETUP4,     IDT_SW_NTP6_BARLIMIT4,
             IDT_SW_NTP6_BARLTBASE4,    IDT_SW_NTP6_BARUTBASE4},
            {IDT_SW_NTP6_BARSETUP5,     IDT_SW_NTP6_BARLIMIT5,
             IDT_SW_NTP6_BARLTBASE5,    IDT_SW_NTP6_BARUTBASE5} } },
/*7*/   {0},
/*8*/   { IDT_SW_NTP8_PCIECMDSTS,       IDT_SW_NTP8_PCIELCTLSTS,
          IDT_SW_NTP8_NTCTL,
          IDT_SW_SWPORT8CTL,            IDT_SW_SWPORT8STS,
          { {IDT_SW_NTP8_BARSETUP0,     IDT_SW_NTP8_BARLIMIT0,
             IDT_SW_NTP8_BARLTBASE0,    IDT_SW_NTP8_BARUTBASE0},
            {IDT_SW_NTP8_BARSETUP1,     IDT_SW_NTP8_BARLIMIT1,
             IDT_SW_NTP8_BARLTBASE1,    IDT_SW_NTP8_BARUTBASE1},
            {IDT_SW_NTP8_BARSETUP2,     IDT_SW_NTP8_BARLIMIT2,
             IDT_SW_NTP8_BARLTBASE2,    IDT_SW_NTP8_BARUTBASE2},
            {IDT_SW_NTP8_BARSETUP3,     IDT_SW_NTP8_BARLIMIT3,
             IDT_SW_NTP8_BARLTBASE3,    IDT_SW_NTP8_BARUTBASE3},
            {IDT_SW_NTP8_BARSETUP4,     IDT_SW_NTP8_BARLIMIT4,
             IDT_SW_NTP8_BARLTBASE4,    IDT_SW_NTP8_BARUTBASE4},
            {IDT_SW_NTP8_BARSETUP5,     IDT_SW_NTP8_BARLIMIT5,
             IDT_SW_NTP8_BARLTBASE5,    IDT_SW_NTP8_BARUTBASE5} } },
/*9*/   {0},
/*10*/  {0},
/*11*/  {0},
/*12*/  { IDT_SW_NTP12_PCIECMDSTS,      IDT_SW_NTP12_PCIELCTLSTS,
          IDT_SW_NTP12_NTCTL,
          IDT_SW_SWPORT12CTL,           IDT_SW_SWPORT12STS,
          { {IDT_SW_NTP12_BARSETUP0,    IDT_SW_NTP12_BARLIMIT0,
             IDT_SW_NTP12_BARLTBASE0,   IDT_SW_NTP12_BARUTBASE0},
            {IDT_SW_NTP12_BARSETUP1,    IDT_SW_NTP12_BARLIMIT1,
             IDT_SW_NTP12_BARLTBASE1,   IDT_SW_NTP12_BARUTBASE1},
            {IDT_SW_NTP12_BARSETUP2,    IDT_SW_NTP12_BARLIMIT2,
             IDT_SW_NTP12_BARLTBASE2,   IDT_SW_NTP12_BARUTBASE2},
            {IDT_SW_NTP12_BARSETUP3,    IDT_SW_NTP12_BARLIMIT3,
             IDT_SW_NTP12_BARLTBASE3,   IDT_SW_NTP12_BARUTBASE3},
            {IDT_SW_NTP12_BARSETUP4,    IDT_SW_NTP12_BARLIMIT4,
             IDT_SW_NTP12_BARLTBASE4,   IDT_SW_NTP12_BARUTBASE4},
            {IDT_SW_NTP12_BARSETUP5,    IDT_SW_NTP12_BARLIMIT5,
             IDT_SW_NTP12_BARLTBASE5,   IDT_SW_NTP12_BARUTBASE5} } },
/*13*/  {0},
/*14*/  {0},
/*15*/  {0},
/*16*/  { IDT_SW_NTP16_PCIECMDSTS,      IDT_SW_NTP16_PCIELCTLSTS,
          IDT_SW_NTP16_NTCTL,
          IDT_SW_SWPORT16CTL,           IDT_SW_SWPORT16STS,
          { {IDT_SW_NTP16_BARSETUP0,    IDT_SW_NTP16_BARLIMIT0,
             IDT_SW_NTP16_BARLTBASE0,   IDT_SW_NTP16_BARUTBASE0},
            {IDT_SW_NTP16_BARSETUP1,    IDT_SW_NTP16_BARLIMIT1,
             IDT_SW_NTP16_BARLTBASE1,   IDT_SW_NTP16_BARUTBASE1},
            {IDT_SW_NTP16_BARSETUP2,    IDT_SW_NTP16_BARLIMIT2,
             IDT_SW_NTP16_BARLTBASE2,   IDT_SW_NTP16_BARUTBASE2},
            {IDT_SW_NTP16_BARSETUP3,    IDT_SW_NTP16_BARLIMIT3,
             IDT_SW_NTP16_BARLTBASE3,   IDT_SW_NTP16_BARUTBASE3},
            {IDT_SW_NTP16_BARSETUP4,    IDT_SW_NTP16_BARLIMIT4,
             IDT_SW_NTP16_BARLTBASE4,   IDT_SW_NTP16_BARUTBASE4},
            {IDT_SW_NTP16_BARSETUP5,    IDT_SW_NTP16_BARLIMIT5,
             IDT_SW_NTP16_BARLTBASE5,   IDT_SW_NTP16_BARUTBASE5} } },
/*17*/  {0},
/*18*/  {0},
/*19*/  {0},
/*20*/  { IDT_SW_NTP20_PCIECMDSTS,      IDT_SW_NTP20_PCIELCTLSTS,
          IDT_SW_NTP20_NTCTL,
          IDT_SW_SWPORT20CTL,           IDT_SW_SWPORT20STS,
          { {IDT_SW_NTP20_BARSETUP0,    IDT_SW_NTP20_BARLIMIT0,
             IDT_SW_NTP20_BARLTBASE0,   IDT_SW_NTP20_BARUTBASE0},
            {IDT_SW_NTP20_BARSETUP1,    IDT_SW_NTP20_BARLIMIT1,
             IDT_SW_NTP20_BARLTBASE1,   IDT_SW_NTP20_BARUTBASE1},
            {IDT_SW_NTP20_BARSETUP2,    IDT_SW_NTP20_BARLIMIT2,
             IDT_SW_NTP20_BARLTBASE2,   IDT_SW_NTP20_BARUTBASE2},
            {IDT_SW_NTP20_BARSETUP3,    IDT_SW_NTP20_BARLIMIT3,
             IDT_SW_NTP20_BARLTBASE3,   IDT_SW_NTP20_BARUTBASE3},
            {IDT_SW_NTP20_BARSETUP4,    IDT_SW_NTP20_BARLIMIT4,
             IDT_SW_NTP20_BARLTBASE4,   IDT_SW_NTP20_BARUTBASE4},
            {IDT_SW_NTP20_BARSETUP5,    IDT_SW_NTP20_BARLIMIT5,
             IDT_SW_NTP20_BARLTBASE5,   IDT_SW_NTP20_BARUTBASE5} } },
/*21*/  {0},
/*22*/  {0},
/*23*/  {0}
};

/*
 * IDT PCIe-switch partitions table with the corresponding control, status
 * and messages control registers
 */
static const struct idt_ntb_part partdata_tbl[IDT_MAX_NR_PARTS] = {
/*0*/   { IDT_SW_SWPART0CTL,    IDT_SW_SWPART0STS,
          {IDT_SW_SWP0MSGCTL0,  IDT_SW_SWP0MSGCTL1,
           IDT_SW_SWP0MSGCTL2,  IDT_SW_SWP0MSGCTL3} },
/*1*/   { IDT_SW_SWPART1CTL,    IDT_SW_SWPART1STS,
          {IDT_SW_SWP1MSGCTL0,  IDT_SW_SWP1MSGCTL1,
           IDT_SW_SWP1MSGCTL2,  IDT_SW_SWP1MSGCTL3} },
/*2*/   { IDT_SW_SWPART2CTL,    IDT_SW_SWPART2STS,
          {IDT_SW_SWP2MSGCTL0,  IDT_SW_SWP2MSGCTL1,
           IDT_SW_SWP2MSGCTL2,  IDT_SW_SWP2MSGCTL3} },
/*3*/   { IDT_SW_SWPART3CTL,    IDT_SW_SWPART3STS,
          {IDT_SW_SWP3MSGCTL0,  IDT_SW_SWP3MSGCTL1,
           IDT_SW_SWP3MSGCTL2,  IDT_SW_SWP3MSGCTL3} },
/*4*/   { IDT_SW_SWPART4CTL,    IDT_SW_SWPART4STS,
          {IDT_SW_SWP4MSGCTL0,  IDT_SW_SWP4MSGCTL1,
           IDT_SW_SWP4MSGCTL2,  IDT_SW_SWP4MSGCTL3} },
/*5*/   { IDT_SW_SWPART5CTL,    IDT_SW_SWPART5STS,
          {IDT_SW_SWP5MSGCTL0,  IDT_SW_SWP5MSGCTL1,
           IDT_SW_SWP5MSGCTL2,  IDT_SW_SWP5MSGCTL3} },
/*6*/   { IDT_SW_SWPART6CTL,    IDT_SW_SWPART6STS,
          {IDT_SW_SWP6MSGCTL0,  IDT_SW_SWP6MSGCTL1,
           IDT_SW_SWP6MSGCTL2,  IDT_SW_SWP6MSGCTL3} },
/*7*/   { IDT_SW_SWPART7CTL,    IDT_SW_SWPART7STS,
          {IDT_SW_SWP7MSGCTL0,  IDT_SW_SWP7MSGCTL1,
           IDT_SW_SWP7MSGCTL2,  IDT_SW_SWP7MSGCTL3} }
};

/*
 * DebugFS directory to place the driver debug file
 */
static struct dentry *dbgfs_topdir;

/*=============================================================================
 *                1. IDT PCIe-switch registers IO-functions
 *
 *    Beside ordinary configuration space registers IDT PCIe-switch expose
 * global configuration registers, which are used to determine state of other
 * device ports as well as being notified of some switch-related events.
 * Additionally all the configuration space registers of all the IDT
 * PCIe-switch functions are mapped to the Global Address space, so each
 * function can determine a configuration of any other PCI-function.
 *    Functions declared in this chapter are created to encapsulate access
 * to configuration and global registers, so the driver code just need to
 * provide IDT NTB hardware descriptor and a register address.
 *=============================================================================
 */

/*
 * idt_nt_write() - PCI configuration space registers write method
 * @ndev:       IDT NTB hardware driver descriptor
 * @reg:        Register to write data to
 * @data:       Value to write to the register
 *
 * IDT PCIe-switch registers are all Little endian.
 */
static void idt_nt_write(struct idt_ntb_dev *ndev,
                         const unsigned int reg, const u32 data)
{
        /*
         * It's obvious bug to request a register exceeding the maximum possible
         * value as well as to have it unaligned.
         */
        if (WARN_ON(reg > IDT_REG_PCI_MAX || !IS_ALIGNED(reg, IDT_REG_ALIGN)))
                return;

        /* Just write the value to the specified register */
        iowrite32(data, ndev->cfgspc + (ptrdiff_t)reg);
}

/*
 * idt_nt_read() - PCI configuration space registers read method
 * @ndev:       IDT NTB hardware driver descriptor
 * @reg:        Register to write data to
 *
 * IDT PCIe-switch Global configuration registers are all Little endian.
 *
 * Return: register value
 */
static u32 idt_nt_read(struct idt_ntb_dev *ndev, const unsigned int reg)
{
        /*
         * It's obvious bug to request a register exceeding the maximum possible
         * value as well as to have it unaligned.
         */
        if (WARN_ON(reg > IDT_REG_PCI_MAX || !IS_ALIGNED(reg, IDT_REG_ALIGN)))
                return ~0;

        /* Just read the value from the specified register */
        return ioread32(ndev->cfgspc + (ptrdiff_t)reg);
}

/*
 * idt_sw_write() - Global registers write method
 * @ndev:       IDT NTB hardware driver descriptor
 * @reg:        Register to write data to
 * @data:       Value to write to the register
 *
 * IDT PCIe-switch Global configuration registers are all Little endian.
 */
static void idt_sw_write(struct idt_ntb_dev *ndev,
                         const unsigned int reg, const u32 data)
{
        unsigned long irqflags;

        /*
         * It's obvious bug to request a register exceeding the maximum possible
         * value as well as to have it unaligned.
         */
        if (WARN_ON(reg > IDT_REG_SW_MAX || !IS_ALIGNED(reg, IDT_REG_ALIGN)))
                return;

        /* Lock GASA registers operations */
        spin_lock_irqsave(&ndev->gasa_lock, irqflags);
        /* Set the global register address */
        iowrite32((u32)reg, ndev->cfgspc + (ptrdiff_t)IDT_NT_GASAADDR);
        /* Put the new value of the register */
        iowrite32(data, ndev->cfgspc + (ptrdiff_t)IDT_NT_GASADATA);
        /* Unlock GASA registers operations */
        spin_unlock_irqrestore(&ndev->gasa_lock, irqflags);
}

/*
 * idt_sw_read() - Global registers read method
 * @ndev:       IDT NTB hardware driver descriptor
 * @reg:        Register to write data to
 *
 * IDT PCIe-switch Global configuration registers are all Little endian.
 *
 * Return: register value
 */
static u32 idt_sw_read(struct idt_ntb_dev *ndev, const unsigned int reg)
{
        unsigned long irqflags;
        u32 data;

        /*
         * It's obvious bug to request a register exceeding the maximum possible
         * value as well as to have it unaligned.
         */
        if (WARN_ON(reg > IDT_REG_SW_MAX || !IS_ALIGNED(reg, IDT_REG_ALIGN)))
                return ~0;

        /* Lock GASA registers operations */
        spin_lock_irqsave(&ndev->gasa_lock, irqflags);
        /* Set the global register address */
        iowrite32((u32)reg, ndev->cfgspc + (ptrdiff_t)IDT_NT_GASAADDR);
        /* Get the data of the register (read ops acts as MMIO barrier) */
        data = ioread32(ndev->cfgspc + (ptrdiff_t)IDT_NT_GASADATA);
        /* Unlock GASA registers operations */
        spin_unlock_irqrestore(&ndev->gasa_lock, irqflags);

        return data;
}

/*
 * idt_reg_set_bits() - set bits of a passed register
 * @ndev:       IDT NTB hardware driver descriptor
 * @reg:        Register to change bits of
 * @reg_lock:   Register access spin lock
 * @valid_mask: Mask of valid bits
 * @set_bits:   Bitmask to set
 *
 * Helper method to check whether a passed bitfield is valid and set
 * corresponding bits of a register.
 *
 * WARNING! Make sure the passed register isn't accessed over plane
 * idt_nt_write() method (read method is ok to be used concurrently).
 *
 * Return: zero on success, negative error on invalid bitmask.
 */
static inline int idt_reg_set_bits(struct idt_ntb_dev *ndev, unsigned int reg,
                                   spinlock_t *reg_lock,
                                   u64 valid_mask, u64 set_bits)
{
        unsigned long irqflags;
        u32 data;

        if (set_bits & ~(u64)valid_mask)
                return -EINVAL;

        /* Lock access to the register unless the change is written back */
        spin_lock_irqsave(reg_lock, irqflags);
        data = idt_nt_read(ndev, reg) | (u32)set_bits;
        idt_nt_write(ndev, reg, data);
        /* Unlock the register */
        spin_unlock_irqrestore(reg_lock, irqflags);

        return 0;
}

/*
 * idt_reg_clear_bits() - clear bits of a passed register
 * @ndev:       IDT NTB hardware driver descriptor
 * @reg:        Register to change bits of
 * @reg_lock:   Register access spin lock
 * @set_bits:   Bitmask to clear
 *
 * Helper method to check whether a passed bitfield is valid and clear
 * corresponding bits of a register.
 *
 * NOTE! Invalid bits are always considered cleared so it's not an error
 * to clear them over.
 *
 * WARNING! Make sure the passed register isn't accessed over plane
 * idt_nt_write() method (read method is ok to use concurrently).
 */
static inline void idt_reg_clear_bits(struct idt_ntb_dev *ndev,
                                     unsigned int reg, spinlock_t *reg_lock,
                                     u64 clear_bits)
{
        unsigned long irqflags;
        u32 data;

        /* Lock access to the register unless the change is written back */
        spin_lock_irqsave(reg_lock, irqflags);
        data = idt_nt_read(ndev, reg) & ~(u32)clear_bits;
        idt_nt_write(ndev, reg, data);
        /* Unlock the register */
        spin_unlock_irqrestore(reg_lock, irqflags);
}

/*===========================================================================
 *                           2. Ports operations
 *
 *    IDT PCIe-switches can have from 3 up to 8 ports with possible
 * NT-functions enabled. So all the possible ports need to be scanned looking
 * for NTB activated. NTB API will have enumerated only the ports with NTB.
 *===========================================================================
 */

/*
 * idt_scan_ports() - scan IDT PCIe-switch ports collecting info in the tables
 * @ndev:       Pointer to the PCI device descriptor
 *
 * Return: zero on success, otherwise a negative error number.
 */
static int idt_scan_ports(struct idt_ntb_dev *ndev)
{
        unsigned char pidx, port, part;
        u32 data, portsts, partsts;

        /* Retrieve the local port number */
        data = idt_nt_read(ndev, IDT_NT_PCIELCAP);
        ndev->port = GET_FIELD(PCIELCAP_PORTNUM, data);

        /* Retrieve the local partition number */
        portsts = idt_sw_read(ndev, portdata_tbl[ndev->port].sts);
        ndev->part = GET_FIELD(SWPORTxSTS_SWPART, portsts);

        /* Initialize port/partition -> index tables with invalid values */
        memset(ndev->port_idx_map, -EINVAL, sizeof(ndev->port_idx_map));
        memset(ndev->part_idx_map, -EINVAL, sizeof(ndev->part_idx_map));

        /*
         * Walk over all the possible ports checking whether any of them has
         * NT-function activated
         */
        ndev->peer_cnt = 0;
        for (pidx = 0; pidx < ndev->swcfg->port_cnt; pidx++) {
                port = ndev->swcfg->ports[pidx];
                /* Skip local port */
                if (port == ndev->port)
                        continue;

                /* Read the port status register to get it partition */
                portsts = idt_sw_read(ndev, portdata_tbl[port].sts);
                part = GET_FIELD(SWPORTxSTS_SWPART, portsts);

                /* Retrieve the partition status */
                partsts = idt_sw_read(ndev, partdata_tbl[part].sts);
                /* Check if partition state is active and port has NTB */
                if (IS_FLD_SET(SWPARTxSTS_STATE, partsts, ACT) &&
                    (IS_FLD_SET(SWPORTxSTS_MODE, portsts, NT) ||
                     IS_FLD_SET(SWPORTxSTS_MODE, portsts, USNT) ||
                     IS_FLD_SET(SWPORTxSTS_MODE, portsts, USNTDMA) ||
                     IS_FLD_SET(SWPORTxSTS_MODE, portsts, NTDMA))) {
                        /* Save the port and partition numbers */
                        ndev->peers[ndev->peer_cnt].port = port;
                        ndev->peers[ndev->peer_cnt].part = part;
                        /* Fill in the port/partition -> index tables */
                        ndev->port_idx_map[port] = ndev->peer_cnt;
                        ndev->part_idx_map[part] = ndev->peer_cnt;
                        ndev->peer_cnt++;
                }
        }

        dev_dbg(&ndev->ntb.pdev->dev, "Local port: %hhu, num of peers: %hhu\n",
                ndev->port, ndev->peer_cnt);

        /* It's useless to have this driver loaded if there is no any peer */
        if (ndev->peer_cnt == 0) {
                dev_warn(&ndev->ntb.pdev->dev, "No active peer found\n");
                return -ENODEV;
        }

        return 0;
}

/*
 * idt_ntb_port_number() - get the local port number
 * @ntb:        NTB device context.
 *
 * Return: the local port number
 */
static int idt_ntb_port_number(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return ndev->port;
}

/*
 * idt_ntb_peer_port_count() - get the number of peer ports
 * @ntb:        NTB device context.
 *
 * Return the count of detected peer NT-functions.
 *
 * Return: number of peer ports
 */
static int idt_ntb_peer_port_count(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return ndev->peer_cnt;
}

/*
 * idt_ntb_peer_port_number() - get peer port by given index
 * @ntb:        NTB device context.
 * @pidx:       Peer port index.
 *
 * Return: peer port or negative error
 */
static int idt_ntb_peer_port_number(struct ntb_dev *ntb, int pidx)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        if (pidx < 0 || ndev->peer_cnt <= pidx)
                return -EINVAL;

        /* Return the detected NT-function port number */
        return ndev->peers[pidx].port;
}

/*
 * idt_ntb_peer_port_idx() - get peer port index by given port number
 * @ntb:        NTB device context.
 * @port:       Peer port number.
 *
 * Internal port -> index table is pre-initialized with -EINVAL values,
 * so we just need to return it value
 *
 * Return: peer NT-function port index or negative error
 */
static int idt_ntb_peer_port_idx(struct ntb_dev *ntb, int port)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        if (port < 0 || IDT_MAX_NR_PORTS <= port)
                return -EINVAL;

        return ndev->port_idx_map[port];
}

/*===========================================================================
 *                         3. Link status operations
 *    There is no any ready-to-use method to have peer ports notified if NTB
 * link is set up or got down. Instead global signal can be used instead.
 * In case if any one of ports changes local NTB link state, it sends
 * global signal and clears corresponding global state bit. Then all the ports
 * receive a notification of that, so to make client driver being aware of
 * possible NTB link change.
 *    Additionally each of active NT-functions is subscribed to PCIe-link
 * state changes of peer ports.
 *===========================================================================
 */

static void idt_ntb_local_link_disable(struct idt_ntb_dev *ndev);

/*
 * idt_init_link() - Initialize NTB link state notification subsystem
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Function performs the basic initialization of some global registers
 * needed to enable IRQ-based notifications of PCIe Link Up/Down and
 * Global Signal events.
 * NOTE Since it's not possible to determine when all the NTB peer drivers are
 * unloaded as well as have those registers accessed concurrently, we must
 * preinitialize them with the same value and leave it uncleared on local
 * driver unload.
 */
static void idt_init_link(struct idt_ntb_dev *ndev)
{
        u32 part_mask, port_mask, se_mask;
        unsigned char pidx;

        /* Initialize spin locker of Mapping Table access registers */
        spin_lock_init(&ndev->mtbl_lock);

        /* Walk over all detected peers collecting port and partition masks */
        port_mask = ~BIT(ndev->port);
        part_mask = ~BIT(ndev->part);
        for (pidx = 0; pidx < ndev->peer_cnt; pidx++) {
                port_mask &= ~BIT(ndev->peers[pidx].port);
                part_mask &= ~BIT(ndev->peers[pidx].part);
        }

        /* Clean the Link Up/Down and GLobal Signal status registers */
        idt_sw_write(ndev, IDT_SW_SELINKUPSTS, (u32)-1);
        idt_sw_write(ndev, IDT_SW_SELINKDNSTS, (u32)-1);
        idt_sw_write(ndev, IDT_SW_SEGSIGSTS, (u32)-1);

        /* Unmask NT-activated partitions to receive Global Switch events */
        idt_sw_write(ndev, IDT_SW_SEPMSK, part_mask);

        /* Enable PCIe Link Up events of NT-activated ports */
        idt_sw_write(ndev, IDT_SW_SELINKUPMSK, port_mask);

        /* Enable PCIe Link Down events of NT-activated ports */
        idt_sw_write(ndev, IDT_SW_SELINKDNMSK, port_mask);

        /* Unmask NT-activated partitions to receive Global Signal events */
        idt_sw_write(ndev, IDT_SW_SEGSIGMSK, part_mask);

        /* Unmask Link Up/Down and Global Switch Events */
        se_mask = ~(IDT_SEMSK_LINKUP | IDT_SEMSK_LINKDN | IDT_SEMSK_GSIGNAL);
        idt_sw_write(ndev, IDT_SW_SEMSK, se_mask);

        dev_dbg(&ndev->ntb.pdev->dev, "NTB link status events initialized");
}

/*
 * idt_deinit_link() - deinitialize link subsystem
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Just disable the link back.
 */
static void idt_deinit_link(struct idt_ntb_dev *ndev)
{
        /* Disable the link */
        idt_ntb_local_link_disable(ndev);

        dev_dbg(&ndev->ntb.pdev->dev, "NTB link status events deinitialized");
}

/*
 * idt_se_isr() - switch events ISR
 * @ndev:       IDT NTB hardware driver descriptor
 * @ntint_sts:  NT-function interrupt status
 *
 * This driver doesn't support IDT PCIe-switch dynamic reconfigurations,
 * Failover capability, etc, so switch events are utilized to notify of
 * PCIe and NTB link events.
 * The method is called from PCIe ISR bottom-half routine.
 */
static void idt_se_isr(struct idt_ntb_dev *ndev, u32 ntint_sts)
{
        u32 sests;

        /* Read Switch Events status */
        sests = idt_sw_read(ndev, IDT_SW_SESTS);

        /* Clean the Link Up/Down and Global Signal status registers */
        idt_sw_write(ndev, IDT_SW_SELINKUPSTS, (u32)-1);
        idt_sw_write(ndev, IDT_SW_SELINKDNSTS, (u32)-1);
        idt_sw_write(ndev, IDT_SW_SEGSIGSTS, (u32)-1);

        /* Clean the corresponding interrupt bit */
        idt_nt_write(ndev, IDT_NT_NTINTSTS, IDT_NTINTSTS_SEVENT);

        dev_dbg(&ndev->ntb.pdev->dev, "SE IRQ detected %#08x (SESTS %#08x)",
                          ntint_sts, sests);

        /* Notify the client driver of possible link state change */
        ntb_link_event(&ndev->ntb);
}

/*
 * idt_ntb_local_link_enable() - enable the local NTB link.
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * In order to enable the NTB link we need:
 * - enable Completion TLPs translation
 * - initialize mapping table to enable the Request ID translation
 * - notify peers of NTB link state change
 */
static void idt_ntb_local_link_enable(struct idt_ntb_dev *ndev)
{
        u32 reqid, mtbldata = 0;
        unsigned long irqflags;

        /* Enable the ID protection and Completion TLPs translation */
        idt_nt_write(ndev, IDT_NT_NTCTL, IDT_NTCTL_CPEN);

        /* Retrieve the current Requester ID (Bus:Device:Function) */
        reqid = idt_nt_read(ndev, IDT_NT_REQIDCAP);

        /*
         * Set the corresponding NT Mapping table entry of port partition index
         * with the data to perform the Request ID translation
         */
        mtbldata = SET_FIELD(NTMTBLDATA_REQID, 0, reqid) |
                   SET_FIELD(NTMTBLDATA_PART, 0, ndev->part) |
                   IDT_NTMTBLDATA_VALID;
        spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
        idt_nt_write(ndev, IDT_NT_NTMTBLADDR, ndev->part);
        idt_nt_write(ndev, IDT_NT_NTMTBLDATA, mtbldata);
        spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);

        /* Notify the peers by setting and clearing the global signal bit */
        idt_nt_write(ndev, IDT_NT_NTGSIGNAL, IDT_NTGSIGNAL_SET);
        idt_sw_write(ndev, IDT_SW_SEGSIGSTS, (u32)1 << ndev->part);
}

/*
 * idt_ntb_local_link_disable() - disable the local NTB link.
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * In order to enable the NTB link we need:
 * - disable Completion TLPs translation
 * - clear corresponding mapping table entry
 * - notify peers of NTB link state change
 */
static void idt_ntb_local_link_disable(struct idt_ntb_dev *ndev)
{
        unsigned long irqflags;

        /* Disable Completion TLPs translation */
        idt_nt_write(ndev, IDT_NT_NTCTL, 0);

        /* Clear the corresponding NT Mapping table entry */
        spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
        idt_nt_write(ndev, IDT_NT_NTMTBLADDR, ndev->part);
        idt_nt_write(ndev, IDT_NT_NTMTBLDATA, 0);
        spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);

        /* Notify the peers by setting and clearing the global signal bit */
        idt_nt_write(ndev, IDT_NT_NTGSIGNAL, IDT_NTGSIGNAL_SET);
        idt_sw_write(ndev, IDT_SW_SEGSIGSTS, (u32)1 << ndev->part);
}

/*
 * idt_ntb_local_link_is_up() - test wethter local NTB link is up
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Local link is up under the following conditions:
 * - Bus mastering is enabled
 * - NTCTL has Completion TLPs translation enabled
 * - Mapping table permits Request TLPs translation
 * NOTE: We don't need to check PCIe link state since it's obviously
 * up while we are able to communicate with IDT PCIe-switch
 *
 * Return: true if link is up, otherwise false
 */
static bool idt_ntb_local_link_is_up(struct idt_ntb_dev *ndev)
{
        unsigned long irqflags;
        u32 data;

        /* Read the local Bus Master Enable status */
        data = idt_nt_read(ndev, IDT_NT_PCICMDSTS);
        if (!(data & IDT_PCICMDSTS_BME))
                return false;

        /* Read the local Completion TLPs translation enable status */
        data = idt_nt_read(ndev, IDT_NT_NTCTL);
        if (!(data & IDT_NTCTL_CPEN))
                return false;

        /* Read Mapping table entry corresponding to the local partition */
        spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
        idt_nt_write(ndev, IDT_NT_NTMTBLADDR, ndev->part);
        data = idt_nt_read(ndev, IDT_NT_NTMTBLDATA);
        spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);

        return !!(data & IDT_NTMTBLDATA_VALID);
}

/*
 * idt_ntb_peer_link_is_up() - test whether peer NTB link is up
 * @ndev:       IDT NTB hardware driver descriptor
 * @pidx:       Peer port index
 *
 * Peer link is up under the following conditions:
 * - PCIe link is up
 * - Bus mastering is enabled
 * - NTCTL has Completion TLPs translation enabled
 * - Mapping table permits Request TLPs translation
 *
 * Return: true if link is up, otherwise false
 */
static bool idt_ntb_peer_link_is_up(struct idt_ntb_dev *ndev, int pidx)
{
        unsigned long irqflags;
        unsigned char port;
        u32 data;

        /* Retrieve the device port number */
        port = ndev->peers[pidx].port;

        /* Check whether PCIe link is up */
        data = idt_sw_read(ndev, portdata_tbl[port].sts);
        if (!(data & IDT_SWPORTxSTS_LINKUP))
                return false;

        /* Check whether bus mastering is enabled on the peer port */
        data = idt_sw_read(ndev, portdata_tbl[port].pcicmdsts);
        if (!(data & IDT_PCICMDSTS_BME))
                return false;

        /* Check if Completion TLPs translation is enabled on the peer port */
        data = idt_sw_read(ndev, portdata_tbl[port].ntctl);
        if (!(data & IDT_NTCTL_CPEN))
                return false;

        /* Read Mapping table entry corresponding to the peer partition */
        spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
        idt_nt_write(ndev, IDT_NT_NTMTBLADDR, ndev->peers[pidx].part);
        data = idt_nt_read(ndev, IDT_NT_NTMTBLDATA);
        spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);

        return !!(data & IDT_NTMTBLDATA_VALID);
}

/*
 * idt_ntb_link_is_up() - get the current ntb link state (NTB API callback)
 * @ntb:        NTB device context.
 * @speed:      OUT - The link speed expressed as PCIe generation number.
 * @width:      OUT - The link width expressed as the number of PCIe lanes.
 *
 * Get the bitfield of NTB link states for all peer ports
 *
 * Return: bitfield of indexed ports link state: bit is set/cleared if the
 *         link is up/down respectively.
 */
static u64 idt_ntb_link_is_up(struct ntb_dev *ntb,
                              enum ntb_speed *speed, enum ntb_width *width)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
        unsigned char pidx;
        u64 status;
        u32 data;

        /* Retrieve the local link speed and width */
        if (speed != NULL || width != NULL) {
                data = idt_nt_read(ndev, IDT_NT_PCIELCTLSTS);
                if (speed != NULL)
                        *speed = GET_FIELD(PCIELCTLSTS_CLS, data);
                if (width != NULL)
                        *width = GET_FIELD(PCIELCTLSTS_NLW, data);
        }

        /* If local NTB link isn't up then all the links are considered down */
        if (!idt_ntb_local_link_is_up(ndev))
                return 0;

        /* Collect all the peer ports link states into the bitfield */
        status = 0;
        for (pidx = 0; pidx < ndev->peer_cnt; pidx++) {
                if (idt_ntb_peer_link_is_up(ndev, pidx))
                        status |= ((u64)1 << pidx);
        }

        return status;
}

/*
 * idt_ntb_link_enable() - enable local port ntb link (NTB API callback)
 * @ntb:        NTB device context.
 * @max_speed:  The maximum link speed expressed as PCIe generation number.
 * @max_width:  The maximum link width expressed as the number of PCIe lanes.
 *
 * Enable just local NTB link. PCIe link parameters are ignored.
 *
 * Return: always zero.
 */
static int idt_ntb_link_enable(struct ntb_dev *ntb, enum ntb_speed speed,
                               enum ntb_width width)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        /* Just enable the local NTB link */
        idt_ntb_local_link_enable(ndev);

        dev_dbg(&ndev->ntb.pdev->dev, "Local NTB link enabled");

        return 0;
}

/*
 * idt_ntb_link_disable() - disable local port ntb link (NTB API callback)
 * @ntb:        NTB device context.
 *
 * Disable just local NTB link.
 *
 * Return: always zero.
 */
static int idt_ntb_link_disable(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        /* Just disable the local NTB link */
        idt_ntb_local_link_disable(ndev);

        dev_dbg(&ndev->ntb.pdev->dev, "Local NTB link disabled");

        return 0;
}

/*=============================================================================
 *                         4. Memory Window operations
 *
 *    IDT PCIe-switches have two types of memory windows: MWs with direct
 * address translation and MWs with LUT based translation. The first type of
 * MWs is simple map of corresponding BAR address space to a memory space
 * of specified target port. So it implemets just ont-to-one mapping. Lookup
 * table in its turn can map one BAR address space to up to 24 different
 * memory spaces of different ports.
 *    NT-functions BARs can be turned on to implement either direct or lookup
 * table based address translations, so:
 * BAR0 - NT configuration registers space/direct address translation
 * BAR1 - direct address translation/upper address of BAR0x64
 * BAR2 - direct address translation/Lookup table with either 12 or 24 entries
 * BAR3 - direct address translation/upper address of BAR2x64
 * BAR4 - direct address translation/Lookup table with either 12 or 24 entries
 * BAR5 - direct address translation/upper address of BAR4x64
 *    Additionally BAR2 and BAR4 can't have 24-entries LUT enabled at the same
 * time. Since the BARs setup can be rather complicated this driver implements
 * a scanning algorithm to have all the possible memory windows configuration
 * covered.
 *
 * NOTE 1 BAR setup must be done before Linux kernel enumerated NT-function
 * of any port, so this driver would have memory windows configurations fixed.
 * In this way all initializations must be performed either by platform BIOS
 * or using EEPROM connected to IDT PCIe-switch master SMBus.
 *
 * NOTE 2 This driver expects BAR0 mapping NT-function configuration space.
 * Easy calculation can give us an upper boundary of 29 possible memory windows
 * per each NT-function if all the BARs are of 32bit type.
 *=============================================================================
 */

/*
 * idt_get_mw_count() - get memory window count
 * @mw_type:    Memory window type
 *
 * Return: number of memory windows with respect to the BAR type
 */
static inline unsigned char idt_get_mw_count(enum idt_mw_type mw_type)
{
        switch (mw_type) {
        case IDT_MW_DIR:
                return 1;
        case IDT_MW_LUT12:
                return 12;
        case IDT_MW_LUT24:
                return 24;
        default:
                break;
        }

        return 0;
}

/*
 * idt_get_mw_name() - get memory window name
 * @mw_type:    Memory window type
 *
 * Return: pointer to a string with name
 */
static inline char *idt_get_mw_name(enum idt_mw_type mw_type)
{
        switch (mw_type) {
        case IDT_MW_DIR:
                return "DIR  ";
        case IDT_MW_LUT12:
                return "LUT12";
        case IDT_MW_LUT24:
                return "LUT24";
        default:
                break;
        }

        return "unknown";
}

/*
 * idt_scan_mws() - scan memory windows of the port
 * @ndev:       IDT NTB hardware driver descriptor
 * @port:       Port to get number of memory windows for
 * @mw_cnt:     Out - number of memory windows
 *
 * It walks over BAR setup registers of the specified port and determines
 * the memory windows parameters if any activated.
 *
 * Return: array of memory windows
 */
static struct idt_mw_cfg *idt_scan_mws(struct idt_ntb_dev *ndev, int port,
                                       unsigned char *mw_cnt)
{
        struct idt_mw_cfg *mws;
        const struct idt_ntb_bar *bars;
        enum idt_mw_type mw_type;
        unsigned char widx, bidx, en_cnt;
        bool bar_64bit = false;
        int aprt_size;
        u32 data;

        mws = devm_kcalloc(&ndev->ntb.pdev->dev, IDT_MAX_NR_MWS,
                           sizeof(*mws), GFP_KERNEL);
        if (!mws)
                return ERR_PTR(-ENOMEM);

        /* Retrieve the array of the BARs registers */
        bars = portdata_tbl[port].bars;

        /* Scan all the BARs belonging to the port */
        *mw_cnt = 0;
        for (bidx = 0; bidx < IDT_BAR_CNT; bidx += 1 + bar_64bit) {
                /* Read BARSETUP register value */
                data = idt_sw_read(ndev, bars[bidx].setup);

                /* Skip disabled BARs */
                if (!(data & IDT_BARSETUP_EN)) {
                        bar_64bit = false;
                        continue;
                }

                /* Skip next BARSETUP if current one has 64bit addressing */
                bar_64bit = IS_FLD_SET(BARSETUP_TYPE, data, 64);

                /* Skip configuration space mapping BARs */
                if (data & IDT_BARSETUP_MODE_CFG)
                        continue;

                /* Retrieve MW type/entries count and aperture size */
                mw_type = GET_FIELD(BARSETUP_ATRAN, data);
                en_cnt = idt_get_mw_count(mw_type);
                aprt_size = (u64)1 << GET_FIELD(BARSETUP_SIZE, data);

                /* Save configurations of all available memory windows */
                for (widx = 0; widx < en_cnt; widx++, (*mw_cnt)++) {
                        /*
                         * IDT can expose a limited number of MWs, so it's bug
                         * to have more than the driver expects
                         */
                        if (*mw_cnt >= IDT_MAX_NR_MWS)
                                return ERR_PTR(-EINVAL);

                        /* Save basic MW info */
                        mws[*mw_cnt].type = mw_type;
                        mws[*mw_cnt].bar = bidx;
                        mws[*mw_cnt].idx = widx;
                        /* It's always DWORD aligned */
                        mws[*mw_cnt].addr_align = IDT_TRANS_ALIGN;
                        /* DIR and LUT approachs differently configure MWs */
                        if (mw_type == IDT_MW_DIR)
                                mws[*mw_cnt].size_max = aprt_size;
                        else if (mw_type == IDT_MW_LUT12)
                                mws[*mw_cnt].size_max = aprt_size / 16;
                        else
                                mws[*mw_cnt].size_max = aprt_size / 32;
                        mws[*mw_cnt].size_align = (mw_type == IDT_MW_DIR) ?
                                IDT_DIR_SIZE_ALIGN : mws[*mw_cnt].size_max;
                }
        }

        return mws;
}

/*
 * idt_init_mws() - initialize memory windows subsystem
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Scan BAR setup registers of local and peer ports to determine the
 * outbound and inbound memory windows parameters
 *
 * Return: zero on success, otherwise a negative error number
 */
static int idt_init_mws(struct idt_ntb_dev *ndev)
{
        struct idt_ntb_peer *peer;
        unsigned char pidx;

        /* Scan memory windows of the local port */
        ndev->mws = idt_scan_mws(ndev, ndev->port, &ndev->mw_cnt);
        if (IS_ERR(ndev->mws)) {
                dev_err(&ndev->ntb.pdev->dev,
                        "Failed to scan mws of local port %hhu", ndev->port);
                return PTR_ERR(ndev->mws);
        }

        /* Scan memory windows of the peer ports */
        for (pidx = 0; pidx < ndev->peer_cnt; pidx++) {
                peer = &ndev->peers[pidx];
                peer->mws = idt_scan_mws(ndev, peer->port, &peer->mw_cnt);
                if (IS_ERR(peer->mws)) {
                        dev_err(&ndev->ntb.pdev->dev,
                                "Failed to scan mws of port %hhu", peer->port);
                        return PTR_ERR(peer->mws);
                }
        }

        /* Initialize spin locker of the LUT registers */
        spin_lock_init(&ndev->lut_lock);

        dev_dbg(&ndev->ntb.pdev->dev, "Outbound and inbound MWs initialized");

        return 0;
}

/*
 * idt_ntb_mw_count() - number of inbound memory windows (NTB API callback)
 * @ntb:        NTB device context.
 * @pidx:       Port index of peer device.
 *
 * The value is returned for the specified peer, so generally speaking it can
 * be different for different port depending on the IDT PCIe-switch
 * initialization.
 *
 * Return: the number of memory windows.
 */
static int idt_ntb_mw_count(struct ntb_dev *ntb, int pidx)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        if (pidx < 0 || ndev->peer_cnt <= pidx)
                return -EINVAL;

        return ndev->peers[pidx].mw_cnt;
}

/*
 * idt_ntb_mw_get_align() - inbound memory window parameters (NTB API callback)
 * @ntb:        NTB device context.
 * @pidx:       Port index of peer device.
 * @widx:       Memory window index.
 * @addr_align: OUT - the base alignment for translating the memory window
 * @size_align: OUT - the size alignment for translating the memory window
 * @size_max:   OUT - the maximum size of the memory window
 *
 * The peer memory window parameters have already been determined, so just
 * return the corresponding values, which mustn't change within session.
 *
 * Return: Zero on success, otherwise a negative error number.
 */
static int idt_ntb_mw_get_align(struct ntb_dev *ntb, int pidx, int widx,
                                resource_size_t *addr_align,
                                resource_size_t *size_align,
                                resource_size_t *size_max)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
        struct idt_ntb_peer *peer;

        if (pidx < 0 || ndev->peer_cnt <= pidx)
                return -EINVAL;

        peer = &ndev->peers[pidx];

        if (widx < 0 || peer->mw_cnt <= widx)
                return -EINVAL;

        if (addr_align != NULL)
                *addr_align = peer->mws[widx].addr_align;

        if (size_align != NULL)
                *size_align = peer->mws[widx].size_align;

        if (size_max != NULL)
                *size_max = peer->mws[widx].size_max;

        return 0;
}

/*
 * idt_ntb_peer_mw_count() - number of outbound memory windows
 *                           (NTB API callback)
 * @ntb:        NTB device context.
 *
 * Outbound memory windows parameters have been determined based on the
 * BAR setup registers value, which are mostly constants within one session.
 *
 * Return: the number of memory windows.
 */
static int idt_ntb_peer_mw_count(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return ndev->mw_cnt;
}

/*
 * idt_ntb_peer_mw_get_addr() - get map address of an outbound memory window
 *                              (NTB API callback)
 * @ntb:        NTB device context.
 * @widx:       Memory window index (within ntb_peer_mw_count() return value).
 * @base:       OUT - the base address of mapping region.
 * @size:       OUT - the size of mapping region.
 *
 * Return just parameters of BAR resources mapping. Size reflects just the size
 * of the resource
 *
 * Return: Zero on success, otherwise a negative error number.
 */
static int idt_ntb_peer_mw_get_addr(struct ntb_dev *ntb, int widx,
                                    phys_addr_t *base, resource_size_t *size)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        if (widx < 0 || ndev->mw_cnt <= widx)
                return -EINVAL;

        /* Mapping address is just properly shifted BAR resource start */
        if (base != NULL)
                *base = pci_resource_start(ntb->pdev, ndev->mws[widx].bar) +
                        ndev->mws[widx].idx * ndev->mws[widx].size_max;

        /* Mapping size has already been calculated at MWs scanning */
        if (size != NULL)
                *size = ndev->mws[widx].size_max;

        return 0;
}

/*
 * idt_ntb_peer_mw_set_trans() - set a translation address of a memory window
 *                               (NTB API callback)
 * @ntb:        NTB device context.
 * @pidx:       Port index of peer device the translation address received from.
 * @widx:       Memory window index.
 * @addr:       The dma address of the shared memory to access.
 * @size:       The size of the shared memory to access.
 *
 * The Direct address translation and LUT base translation is initialized a
 * bit differenet. Although the parameters restriction are now determined by
 * the same code.
 *
 * Return: Zero on success, otherwise an error number.
 */
static int idt_ntb_peer_mw_set_trans(struct ntb_dev *ntb, int pidx, int widx,
                                     u64 addr, resource_size_t size)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
        struct idt_mw_cfg *mw_cfg;
        u32 data = 0, lutoff = 0;

        if (pidx < 0 || ndev->peer_cnt <= pidx)
                return -EINVAL;

        if (widx < 0 || ndev->mw_cnt <= widx)
                return -EINVAL;

        /*
         * Retrieve the memory window config to make sure the passed arguments
         * fit it restrictions
         */
        mw_cfg = &ndev->mws[widx];
        if (!IS_ALIGNED(addr, mw_cfg->addr_align))
                return -EINVAL;
        if (!IS_ALIGNED(size, mw_cfg->size_align) || size > mw_cfg->size_max)
                return -EINVAL;

        /* DIR and LUT based translations are initialized differently */
        if (mw_cfg->type == IDT_MW_DIR) {
                const struct idt_ntb_bar *bar = &ntdata_tbl.bars[mw_cfg->bar];
                u64 limit;
                /* Set destination partition of translation */
                data = idt_nt_read(ndev, bar->setup);
                data = SET_FIELD(BARSETUP_TPART, data, ndev->peers[pidx].part);
                idt_nt_write(ndev, bar->setup, data);
                /* Set translation base address */
                idt_nt_write(ndev, bar->ltbase, (u32)addr);
                idt_nt_write(ndev, bar->utbase, (u32)(addr >> 32));
                /* Set the custom BAR aperture limit */
                limit = pci_bus_address(ntb->pdev, mw_cfg->bar) + size;
                idt_nt_write(ndev, bar->limit, (u32)limit);
                if (IS_FLD_SET(BARSETUP_TYPE, data, 64))
                        idt_nt_write(ndev, (bar + 1)->limit, (limit >> 32));
        } else {
                unsigned long irqflags;
                /* Initialize corresponding LUT entry */
                lutoff = SET_FIELD(LUTOFFSET_INDEX, 0, mw_cfg->idx) |
                         SET_FIELD(LUTOFFSET_BAR, 0, mw_cfg->bar);
                data = SET_FIELD(LUTUDATA_PART, 0, ndev->peers[pidx].part) |
                        IDT_LUTUDATA_VALID;
                spin_lock_irqsave(&ndev->lut_lock, irqflags);
                idt_nt_write(ndev, IDT_NT_LUTOFFSET, lutoff);
                idt_nt_write(ndev, IDT_NT_LUTLDATA, (u32)addr);
                idt_nt_write(ndev, IDT_NT_LUTMDATA, (u32)(addr >> 32));
                idt_nt_write(ndev, IDT_NT_LUTUDATA, data);
                spin_unlock_irqrestore(&ndev->lut_lock, irqflags);
                /* Limit address isn't specified since size is fixed for LUT */
        }

        return 0;
}

/*
 * idt_ntb_peer_mw_clear_trans() - clear the outbound MW translation address
 *                                 (NTB API callback)
 * @ntb:        NTB device context.
 * @pidx:       Port index of peer device.
 * @widx:       Memory window index.
 *
 * It effectively disables the translation over the specified outbound MW.
 *
 * Return: Zero on success, otherwise an error number.
 */
static int idt_ntb_peer_mw_clear_trans(struct ntb_dev *ntb, int pidx,
                                        int widx)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
        struct idt_mw_cfg *mw_cfg;

        if (pidx < 0 || ndev->peer_cnt <= pidx)
                return -EINVAL;

        if (widx < 0 || ndev->mw_cnt <= widx)
                return -EINVAL;

        mw_cfg = &ndev->mws[widx];

        /* DIR and LUT based translations are initialized differently */
        if (mw_cfg->type == IDT_MW_DIR) {
                const struct idt_ntb_bar *bar = &ntdata_tbl.bars[mw_cfg->bar];
                u32 data;
                /* Read BARSETUP to check BAR type */
                data = idt_nt_read(ndev, bar->setup);
                /* Disable translation by specifying zero BAR limit */
                idt_nt_write(ndev, bar->limit, 0);
                if (IS_FLD_SET(BARSETUP_TYPE, data, 64))
                        idt_nt_write(ndev, (bar + 1)->limit, 0);
        } else {
                unsigned long irqflags;
                u32 lutoff;
                /* Clear the corresponding LUT entry up */
                lutoff = SET_FIELD(LUTOFFSET_INDEX, 0, mw_cfg->idx) |
                         SET_FIELD(LUTOFFSET_BAR, 0, mw_cfg->bar);
                spin_lock_irqsave(&ndev->lut_lock, irqflags);
                idt_nt_write(ndev, IDT_NT_LUTOFFSET, lutoff);
                idt_nt_write(ndev, IDT_NT_LUTLDATA, 0);
                idt_nt_write(ndev, IDT_NT_LUTMDATA, 0);
                idt_nt_write(ndev, IDT_NT_LUTUDATA, 0);
                spin_unlock_irqrestore(&ndev->lut_lock, irqflags);
        }

        return 0;
}

/*=============================================================================
 *                          5. Doorbell operations
 *
 *    Doorbell functionality of IDT PCIe-switches is pretty unusual. First of
 * all there is global doorbell register which state can be changed by any
 * NT-function of the IDT device in accordance with global permissions. These
 * permissions configs are not supported by NTB API, so it must be done by
 * either BIOS or EEPROM settings. In the same way the state of the global
 * doorbell is reflected to the NT-functions local inbound doorbell registers.
 * It can lead to situations when client driver sets some peer doorbell bits
 * and get them bounced back to local inbound doorbell if permissions are
 * granted.
 *    Secondly there is just one IRQ vector for Doorbell, Message, Temperature
 * and Switch events, so if client driver left any of Doorbell bits set and
 * some other event occurred, the driver will be notified of Doorbell event
 * again.
 *=============================================================================
 */

/*
 * idt_db_isr() - doorbell event ISR
 * @ndev:       IDT NTB hardware driver descriptor
 * @ntint_sts:  NT-function interrupt status
 *
 * Doorbell event happans when DBELL bit of NTINTSTS switches from 0 to 1.
 * It happens only when unmasked doorbell bits are set to ones on completely
 * zeroed doorbell register.
 * The method is called from PCIe ISR bottom-half routine.
 */
static void idt_db_isr(struct idt_ntb_dev *ndev, u32 ntint_sts)
{
        /*
         * Doorbell IRQ status will be cleaned only when client
         * driver unsets all the doorbell bits.
         */
        dev_dbg(&ndev->ntb.pdev->dev, "DB IRQ detected %#08x", ntint_sts);

        /* Notify the client driver of possible doorbell state change */
        ntb_db_event(&ndev->ntb, 0);
}

/*
 * idt_ntb_db_valid_mask() - get a mask of doorbell bits supported by the ntb
 *                           (NTB API callback)
 * @ntb:        NTB device context.
 *
 * IDT PCIe-switches expose just one Doorbell register of DWORD size.
 *
 * Return: A mask of doorbell bits supported by the ntb.
 */
static u64 idt_ntb_db_valid_mask(struct ntb_dev *ntb)
{
        return IDT_DBELL_MASK;
}

/*
 * idt_ntb_db_read() - read the local doorbell register (NTB API callback)
 * @ntb:        NTB device context.
 *
 * There is just on inbound doorbell register of each NT-function, so
 * this method return it value.
 *
 * Return: The bits currently set in the local doorbell register.
 */
static u64 idt_ntb_db_read(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return idt_nt_read(ndev, IDT_NT_INDBELLSTS);
}

/*
 * idt_ntb_db_clear() - clear bits in the local doorbell register
 *                      (NTB API callback)
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to clear.
 *
 * Clear bits of inbound doorbell register by writing ones to it.
 *
 * NOTE! Invalid bits are always considered cleared so it's not an error
 * to clear them over.
 *
 * Return: always zero as success.
 */
static int idt_ntb_db_clear(struct ntb_dev *ntb, u64 db_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        idt_nt_write(ndev, IDT_NT_INDBELLSTS, (u32)db_bits);

        return 0;
}

/*
 * idt_ntb_db_read_mask() - read the local doorbell mask (NTB API callback)
 * @ntb:        NTB device context.
 *
 * Each inbound doorbell bit can be masked from generating IRQ by setting
 * the corresponding bit in inbound doorbell mask. So this method returns
 * the value of the register.
 *
 * Return: The bits currently set in the local doorbell mask register.
 */
static u64 idt_ntb_db_read_mask(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return idt_nt_read(ndev, IDT_NT_INDBELLMSK);
}

/*
 * idt_ntb_db_set_mask() - set bits in the local doorbell mask
 *                         (NTB API callback)
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell mask bits to set.
 *
 * The inbound doorbell register mask value must be read, then OR'ed with
 * passed field and only then set back.
 *
 * Return: zero on success, negative error if invalid argument passed.
 */
static int idt_ntb_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return idt_reg_set_bits(ndev, IDT_NT_INDBELLMSK, &ndev->db_mask_lock,
                                IDT_DBELL_MASK, db_bits);
}

/*
 * idt_ntb_db_clear_mask() - clear bits in the local doorbell mask
 *                           (NTB API callback)
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to clear.
 *
 * The method just clears the set bits up in accordance with the passed
 * bitfield. IDT PCIe-switch shall generate an interrupt if there hasn't
 * been any unmasked bit set before current unmasking. Otherwise IRQ won't
 * be generated since there is only one IRQ vector for all doorbells.
 *
 * Return: always zero as success
 */
static int idt_ntb_db_clear_mask(struct ntb_dev *ntb, u64 db_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        idt_reg_clear_bits(ndev, IDT_NT_INDBELLMSK, &ndev->db_mask_lock,
                           db_bits);

        return 0;
}

/*
 * idt_ntb_peer_db_set() - set bits in the peer doorbell register
 *                         (NTB API callback)
 * @ntb:        NTB device context.
 * @db_bits:    Doorbell bits to set.
 *
 * IDT PCIe-switches exposes local outbound doorbell register to change peer
 * inbound doorbell register state.
 *
 * Return: zero on success, negative error if invalid argument passed.
 */
static int idt_ntb_peer_db_set(struct ntb_dev *ntb, u64 db_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        if (db_bits & ~(u64)IDT_DBELL_MASK)
                return -EINVAL;

        idt_nt_write(ndev, IDT_NT_OUTDBELLSET, (u32)db_bits);
        return 0;
}

/*=============================================================================
 *                          6. Messaging operations
 *
 *    Each NT-function of IDT PCIe-switch has four inbound and four outbound
 * message registers. Each outbound message register can be connected to one or
 * even more than one peer inbound message registers by setting global
 * configurations. Since NTB API permits one-on-one message registers mapping
 * only, the driver acts in according with that restriction.
 *=============================================================================
 */

/*
 * idt_init_msg() - initialize messaging interface
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Just initialize the message registers routing tables locker.
 */
static void idt_init_msg(struct idt_ntb_dev *ndev)
{
        unsigned char midx;

        /* Init the messages routing table lockers */
        for (midx = 0; midx < IDT_MSG_CNT; midx++)
                spin_lock_init(&ndev->msg_locks[midx]);

        dev_dbg(&ndev->ntb.pdev->dev, "NTB Messaging initialized");
}

/*
 * idt_msg_isr() - message event ISR
 * @ndev:       IDT NTB hardware driver descriptor
 * @ntint_sts:  NT-function interrupt status
 *
 * Message event happens when MSG bit of NTINTSTS switches from 0 to 1.
 * It happens only when unmasked message status bits are set to ones on
 * completely zeroed message status register.
 * The method is called from PCIe ISR bottom-half routine.
 */
static void idt_msg_isr(struct idt_ntb_dev *ndev, u32 ntint_sts)
{
        /*
         * Message IRQ status will be cleaned only when client
         * driver unsets all the message status bits.
         */
        dev_dbg(&ndev->ntb.pdev->dev, "Message IRQ detected %#08x", ntint_sts);

        /* Notify the client driver of possible message status change */
        ntb_msg_event(&ndev->ntb);
}

/*
 * idt_ntb_msg_count() - get the number of message registers (NTB API callback)
 * @ntb:        NTB device context.
 *
 * IDT PCIe-switches support four message registers.
 *
 * Return: the number of message registers.
 */
static int idt_ntb_msg_count(struct ntb_dev *ntb)
{
        return IDT_MSG_CNT;
}

/*
 * idt_ntb_msg_inbits() - get a bitfield of inbound message registers status
 *                        (NTB API callback)
 * @ntb:        NTB device context.
 *
 * NT message status register is shared between inbound and outbound message
 * registers status
 *
 * Return: bitfield of inbound message registers.
 */
static u64 idt_ntb_msg_inbits(struct ntb_dev *ntb)
{
        return (u64)IDT_INMSG_MASK;
}

/*
 * idt_ntb_msg_outbits() - get a bitfield of outbound message registers status
 *                        (NTB API callback)
 * @ntb:        NTB device context.
 *
 * NT message status register is shared between inbound and outbound message
 * registers status
 *
 * Return: bitfield of outbound message registers.
 */
static u64 idt_ntb_msg_outbits(struct ntb_dev *ntb)
{
        return (u64)IDT_OUTMSG_MASK;
}

/*
 * idt_ntb_msg_read_sts() - read the message registers status (NTB API callback)
 * @ntb:        NTB device context.
 *
 * IDT PCIe-switches expose message status registers to notify drivers of
 * incoming data and failures in case if peer message register isn't freed.
 *
 * Return: status bits of message registers
 */
static u64 idt_ntb_msg_read_sts(struct ntb_dev *ntb)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return idt_nt_read(ndev, IDT_NT_MSGSTS);
}

/*
 * idt_ntb_msg_clear_sts() - clear status bits of message registers
 *                           (NTB API callback)
 * @ntb:        NTB device context.
 * @sts_bits:   Status bits to clear.
 *
 * Clear bits in the status register by writing ones.
 *
 * NOTE! Invalid bits are always considered cleared so it's not an error
 * to clear them over.
 *
 * Return: always zero as success.
 */
static int idt_ntb_msg_clear_sts(struct ntb_dev *ntb, u64 sts_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        idt_nt_write(ndev, IDT_NT_MSGSTS, sts_bits);

        return 0;
}

/*
 * idt_ntb_msg_set_mask() - set mask of message register status bits
 *                          (NTB API callback)
 * @ntb:        NTB device context.
 * @mask_bits:  Mask bits.
 *
 * Mask the message status bits from raising an IRQ.
 *
 * Return: zero on success, negative error if invalid argument passed.
 */
static int idt_ntb_msg_set_mask(struct ntb_dev *ntb, u64 mask_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        return idt_reg_set_bits(ndev, IDT_NT_MSGSTSMSK, &ndev->msg_mask_lock,
                                IDT_MSG_MASK, mask_bits);
}

/*
 * idt_ntb_msg_clear_mask() - clear message registers mask
 *                            (NTB API callback)
 * @ntb:        NTB device context.
 * @mask_bits:  Mask bits.
 *
 * Clear mask of message status bits IRQs.
 *
 * Return: always zero as success.
 */
static int idt_ntb_msg_clear_mask(struct ntb_dev *ntb, u64 mask_bits)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        idt_reg_clear_bits(ndev, IDT_NT_MSGSTSMSK, &ndev->msg_mask_lock,
                           mask_bits);

        return 0;
}

/*
 * idt_ntb_msg_read() - read message register with specified index
 *                      (NTB API callback)
 * @ntb:        NTB device context.
 * @pidx:       OUT - Port index of peer device a message retrieved from
 * @midx:       Message register index
 *
 * Read data from the specified message register and source register.
 *
 * Return: inbound message register value.
 */
static u32 idt_ntb_msg_read(struct ntb_dev *ntb, int *pidx, int midx)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);

        if (midx < 0 || IDT_MSG_CNT <= midx)
                return ~(u32)0;

        /* Retrieve source port index of the message */
        if (pidx != NULL) {
                u32 srcpart;

                srcpart = idt_nt_read(ndev, ntdata_tbl.msgs[midx].src);
                *pidx = ndev->part_idx_map[srcpart];

                /* Sanity check partition index (for initial case) */
                if (*pidx == -EINVAL)
                        *pidx = 0;
        }

        /* Retrieve data of the corresponding message register */
        return idt_nt_read(ndev, ntdata_tbl.msgs[midx].in);
}

/*
 * idt_ntb_peer_msg_write() - write data to the specified message register
 *                            (NTB API callback)
 * @ntb:        NTB device context.
 * @pidx:       Port index of peer device a message being sent to
 * @midx:       Message register index
 * @msg:        Data to send
 *
 * Just try to send data to a peer. Message status register should be
 * checked by client driver.
 *
 * Return: zero on success, negative error if invalid argument passed.
 */
static int idt_ntb_peer_msg_write(struct ntb_dev *ntb, int pidx, int midx,
                                  u32 msg)
{
        struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
        unsigned long irqflags;
        u32 swpmsgctl = 0;

        if (midx < 0 || IDT_MSG_CNT <= midx)
                return -EINVAL;

        if (pidx < 0 || ndev->peer_cnt <= pidx)
                return -EINVAL;

        /* Collect the routing information */
        swpmsgctl = SET_FIELD(SWPxMSGCTL_REG, 0, midx) |
                    SET_FIELD(SWPxMSGCTL_PART, 0, ndev->peers[pidx].part);

        /* Lock the messages routing table of the specified register */
        spin_lock_irqsave(&ndev->msg_locks[midx], irqflags);
        /* Set the route and send the data */
        idt_sw_write(ndev, partdata_tbl[ndev->part].msgctl[midx], swpmsgctl);
        idt_nt_write(ndev, ntdata_tbl.msgs[midx].out, msg);
        /* Unlock the messages routing table */
        spin_unlock_irqrestore(&ndev->msg_locks[midx], irqflags);

        /* Client driver shall check the status register */
        return 0;
}

/*=============================================================================
 *                      7. Temperature sensor operations
 *
 *    IDT PCIe-switch has an embedded temperature sensor, which can be used to
 * check current chip core temperature. Since a workload environment can be
 * different on different platforms, an offset and ADC/filter settings can be
 * specified. Although the offset configuration is only exposed to the sysfs
 * hwmon interface at the moment. The rest of the settings can be adjusted
 * for instance by the BIOS/EEPROM firmware.
 *=============================================================================
 */

/*
 * idt_get_deg() - convert millidegree Celsius value to just degree
 * @mdegC:      IN - millidegree Celsius value
 *
 * Return: Degree corresponding to the passed millidegree value
 */
static inline s8 idt_get_deg(long mdegC)
{
        return mdegC / 1000;
}

/*
 * idt_get_frac() - retrieve 0/0.5 fraction of the millidegree Celsius value
 * @mdegC:      IN - millidegree Celsius value
 *
 * Return: 0/0.5 degree fraction of the passed millidegree value
 */
static inline u8 idt_get_deg_frac(long mdegC)
{
        return (mdegC % 1000) >= 500 ? 5 : 0;
}

/*
 * idt_get_temp_fmt() - convert millidegree Celsius value to 0:7:1 format
 * @mdegC:      IN - millidegree Celsius value
 *
 * Return: 0:7:1 format acceptable by the IDT temperature sensor
 */
static inline u8 idt_temp_get_fmt(long mdegC)
{
        return (idt_get_deg(mdegC) << 1) | (idt_get_deg_frac(mdegC) ? 1 : 0);
}

/*
 * idt_get_temp_sval() - convert temp sample to signed millidegree Celsius
 * @data:       IN - shifted to LSB 8-bits temperature sample
 *
 * Return: signed millidegree Celsius
 */
static inline long idt_get_temp_sval(u32 data)
{
        return ((s8)data / 2) * 1000 + (data & 0x1 ? 500 : 0);
}

/*
 * idt_get_temp_sval() - convert temp sample to unsigned millidegree Celsius
 * @data:       IN - shifted to LSB 8-bits temperature sample
 *
 * Return: unsigned millidegree Celsius
 */
static inline long idt_get_temp_uval(u32 data)
{
        return (data / 2) * 1000 + (data & 0x1 ? 500 : 0);
}

/*
 * idt_read_temp() - read temperature from chip sensor
 * @ntb:        NTB device context.
 * @type:       IN - type of the temperature value to read
 * @val:        OUT - integer value of temperature in millidegree Celsius
 */
static void idt_read_temp(struct idt_ntb_dev *ndev,
                          const enum idt_temp_val type, long *val)
{
        u32 data;

        /* Alter the temperature field in accordance with the passed type */
        switch (type) {
        case IDT_TEMP_CUR:
                data = GET_FIELD(TMPSTS_TEMP,
                                 idt_sw_read(ndev, IDT_SW_TMPSTS));
                break;
        case IDT_TEMP_LOW:
                data = GET_FIELD(TMPSTS_LTEMP,
                                 idt_sw_read(ndev, IDT_SW_TMPSTS));
                break;
        case IDT_TEMP_HIGH:
                data = GET_FIELD(TMPSTS_HTEMP,
                                 idt_sw_read(ndev, IDT_SW_TMPSTS));
                break;
        case IDT_TEMP_OFFSET:
                /* This is the only field with signed 0:7:1 format */
                data = GET_FIELD(TMPADJ_OFFSET,
                                 idt_sw_read(ndev, IDT_SW_TMPADJ));
                *val = idt_get_temp_sval(data);
                return;
        default:
                data = GET_FIELD(TMPSTS_TEMP,
                                 idt_sw_read(ndev, IDT_SW_TMPSTS));
                break;
        }

        /* The rest of the fields accept unsigned 0:7:1 format */
        *val = idt_get_temp_uval(data);
}

/*
 * idt_write_temp() - write temperature to the chip sensor register
 * @ntb:        NTB device context.
 * @type:       IN - type of the temperature value to change
 * @val:        IN - integer value of temperature in millidegree Celsius
 */
static void idt_write_temp(struct idt_ntb_dev *ndev,
                           const enum idt_temp_val type, const long val)
{
        unsigned int reg;
        u32 data;
        u8 fmt;

        /* Retrieve the properly formatted temperature value */
        fmt = idt_temp_get_fmt(val);

        mutex_lock(&ndev->hwmon_mtx);
        switch (type) {
        case IDT_TEMP_LOW:
                reg = IDT_SW_TMPALARM;
                data = SET_FIELD(TMPALARM_LTEMP, idt_sw_read(ndev, reg), fmt) &
                        ~IDT_TMPALARM_IRQ_MASK;
                break;
        case IDT_TEMP_HIGH:
                reg = IDT_SW_TMPALARM;
                data = SET_FIELD(TMPALARM_HTEMP, idt_sw_read(ndev, reg), fmt) &
                        ~IDT_TMPALARM_IRQ_MASK;
                break;
        case IDT_TEMP_OFFSET:
                reg = IDT_SW_TMPADJ;
                data = SET_FIELD(TMPADJ_OFFSET, idt_sw_read(ndev, reg), fmt);
                break;
        default:
                goto inval_spin_unlock;
        }

        idt_sw_write(ndev, reg, data);

inval_spin_unlock:
        mutex_unlock(&ndev->hwmon_mtx);
}

/*
 * idt_sysfs_show_temp() - printout corresponding temperature value
 * @dev:        Pointer to the NTB device structure
 * @da:         Sensor device attribute structure
 * @buf:        Buffer to print temperature out
 *
 * Return: Number of written symbols or negative error
 */
static ssize_t idt_sysfs_show_temp(struct device *dev,
                                   struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct idt_ntb_dev *ndev = dev_get_drvdata(dev);
        enum idt_temp_val type = attr->index;
        long mdeg;

        idt_read_temp(ndev, type, &mdeg);
        return sprintf(buf, "%ld\n", mdeg);
}

/*
 * idt_sysfs_set_temp() - set corresponding temperature value
 * @dev:        Pointer to the NTB device structure
 * @da:         Sensor device attribute structure
 * @buf:        Buffer to print temperature out
 * @count:      Size of the passed buffer
 *
 * Return: Number of written symbols or negative error
 */
static ssize_t idt_sysfs_set_temp(struct device *dev,
                                  struct device_attribute *da, const char *buf,
                                  size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct idt_ntb_dev *ndev = dev_get_drvdata(dev);
        enum idt_temp_val type = attr->index;
        long mdeg;
        int ret;

        ret = kstrtol(buf, 10, &mdeg);
        if (ret)
                return ret;

        /* Clamp the passed value in accordance with the type */
        if (type == IDT_TEMP_OFFSET)
                mdeg = clamp_val(mdeg, IDT_TEMP_MIN_OFFSET,
                                 IDT_TEMP_MAX_OFFSET);
        else
                mdeg = clamp_val(mdeg, IDT_TEMP_MIN_MDEG, IDT_TEMP_MAX_MDEG);

        idt_write_temp(ndev, type, mdeg);

        return count;
}

/*
 * idt_sysfs_reset_hist() - reset temperature history
 * @dev:        Pointer to the NTB device structure
 * @da:         Sensor device attribute structure
 * @buf:        Buffer to print temperature out
 * @count:      Size of the passed buffer
 *
 * Return: Number of written symbols or negative error
 */
static ssize_t idt_sysfs_reset_hist(struct device *dev,
                                    struct device_attribute *da,
                                    const char *buf, size_t count)
{
        struct idt_ntb_dev *ndev = dev_get_drvdata(dev);

        /* Just set the maximal value to the lowest temperature field and
         * minimal value to the highest temperature field
         */
        idt_write_temp(ndev, IDT_TEMP_LOW, IDT_TEMP_MAX_MDEG);
        idt_write_temp(ndev, IDT_TEMP_HIGH, IDT_TEMP_MIN_MDEG);

        return count;
}

/*
 * Hwmon IDT sysfs attributes
 */
static SENSOR_DEVICE_ATTR(temp1_input, 0444, idt_sysfs_show_temp, NULL,
                          IDT_TEMP_CUR);
static SENSOR_DEVICE_ATTR(temp1_lowest, 0444, idt_sysfs_show_temp, NULL,
                          IDT_TEMP_LOW);
static SENSOR_DEVICE_ATTR(temp1_highest, 0444, idt_sysfs_show_temp, NULL,
                          IDT_TEMP_HIGH);
static SENSOR_DEVICE_ATTR(temp1_offset, 0644, idt_sysfs_show_temp,
                          idt_sysfs_set_temp, IDT_TEMP_OFFSET);
static DEVICE_ATTR(temp1_reset_history, 0200, NULL, idt_sysfs_reset_hist);

/*
 * Hwmon IDT sysfs attributes group
 */
static struct attribute *idt_temp_attrs[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp1_lowest.dev_attr.attr,
        &sensor_dev_attr_temp1_highest.dev_attr.attr,
        &sensor_dev_attr_temp1_offset.dev_attr.attr,
        &dev_attr_temp1_reset_history.attr,
        NULL
};
ATTRIBUTE_GROUPS(idt_temp);

/*
 * idt_init_temp() - initialize temperature sensor interface
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Simple sensor initializarion method is responsible for device switching
 * on and resource management based hwmon interface registration. Note, that
 * since the device is shared we won't disable it on remove, but leave it
 * working until the system is powered off.
 */
static void idt_init_temp(struct idt_ntb_dev *ndev)
{
        struct device *hwmon;

        /* Enable sensor if it hasn't been already */
        idt_sw_write(ndev, IDT_SW_TMPCTL, 0x0);

        /* Initialize hwmon interface fields */
        mutex_init(&ndev->hwmon_mtx);

        hwmon = devm_hwmon_device_register_with_groups(&ndev->ntb.pdev->dev,
                ndev->swcfg->name, ndev, idt_temp_groups);
        if (IS_ERR(hwmon)) {
                dev_err(&ndev->ntb.pdev->dev, "Couldn't create hwmon device");
                return;
        }

        dev_dbg(&ndev->ntb.pdev->dev, "Temperature HWmon interface registered");
}

/*=============================================================================
 *                           8. ISRs related operations
 *
 *    IDT PCIe-switch has strangely developed IRQ system. There is just one
 * interrupt vector for doorbell and message registers. So the hardware driver
 * can't determine actual source of IRQ if, for example, message event happened
 * while any of unmasked doorbell is still set. The similar situation may be if
 * switch or temperature sensor events pop up. The difference is that SEVENT
 * and TMPSENSOR bits of NT interrupt status register can be cleaned by
 * IRQ handler so a next interrupt request won't have false handling of
 * corresponding events.
 *    The hardware driver has only bottom-half handler of the IRQ, since if any
 * of events happened the device won't raise it again before the last one is
 * handled by clearing of corresponding NTINTSTS bit.
 *=============================================================================
 */

static irqreturn_t idt_thread_isr(int irq, void *devid);

/*
 * idt_init_isr() - initialize PCIe interrupt handler
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Return: zero on success, otherwise a negative error number.
 */
static int idt_init_isr(struct idt_ntb_dev *ndev)
{
        struct pci_dev *pdev = ndev->ntb.pdev;
        u32 ntint_mask;
        int ret;

        /* Allocate just one interrupt vector for the ISR */
        ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI | PCI_IRQ_INTX);
        if (ret != 1) {
                dev_err(&pdev->dev, "Failed to allocate IRQ vector");
                return ret;
        }

        /* Retrieve the IRQ vector */
        ret = pci_irq_vector(pdev, 0);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to get IRQ vector");
                goto err_free_vectors;
        }

        /* Set the IRQ handler */
        ret = devm_request_threaded_irq(&pdev->dev, ret, NULL, idt_thread_isr,
                                        IRQF_ONESHOT, NTB_IRQNAME, ndev);
        if (ret != 0) {
                dev_err(&pdev->dev, "Failed to set MSI IRQ handler, %d", ret);
                goto err_free_vectors;
        }

        /* Unmask Message/Doorbell/SE interrupts */
        ntint_mask = idt_nt_read(ndev, IDT_NT_NTINTMSK) & ~IDT_NTINTMSK_ALL;
        idt_nt_write(ndev, IDT_NT_NTINTMSK, ntint_mask);

        /* From now on the interrupts are enabled */
        dev_dbg(&pdev->dev, "NTB interrupts initialized");

        return 0;

err_free_vectors:
        pci_free_irq_vectors(pdev);

        return ret;
}

/*
 * idt_deinit_ist() - deinitialize PCIe interrupt handler
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Disable corresponding interrupts and free allocated IRQ vectors.
 */
static void idt_deinit_isr(struct idt_ntb_dev *ndev)
{
        struct pci_dev *pdev = ndev->ntb.pdev;
        u32 ntint_mask;

        /* Mask interrupts back */
        ntint_mask = idt_nt_read(ndev, IDT_NT_NTINTMSK) | IDT_NTINTMSK_ALL;
        idt_nt_write(ndev, IDT_NT_NTINTMSK, ntint_mask);

        /* Manually free IRQ otherwise PCI free irq vectors will fail */
        devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 0), ndev);

        /* Free allocated IRQ vectors */
        pci_free_irq_vectors(pdev);

        dev_dbg(&pdev->dev, "NTB interrupts deinitialized");
}

/*
 * idt_thread_isr() - NT function interrupts handler
 * @irq:        IRQ number
 * @devid:      Custom buffer
 *
 * It reads current NT interrupts state register and handles all the event
 * it declares.
 * The method is bottom-half routine of actual default PCIe IRQ handler.
 */
static irqreturn_t idt_thread_isr(int irq, void *devid)
{
        struct idt_ntb_dev *ndev = devid;
        bool handled = false;
        u32 ntint_sts;

        /* Read the NT interrupts status register */
        ntint_sts = idt_nt_read(ndev, IDT_NT_NTINTSTS);

        /* Handle messaging interrupts */
        if (ntint_sts & IDT_NTINTSTS_MSG) {
                idt_msg_isr(ndev, ntint_sts);
                handled = true;
        }

        /* Handle doorbell interrupts */
        if (ntint_sts & IDT_NTINTSTS_DBELL) {
                idt_db_isr(ndev, ntint_sts);
                handled = true;
        }

        /* Handle switch event interrupts */
        if (ntint_sts & IDT_NTINTSTS_SEVENT) {
                idt_se_isr(ndev, ntint_sts);
                handled = true;
        }

        dev_dbg(&ndev->ntb.pdev->dev, "IDT IRQs 0x%08x handled", ntint_sts);

        return handled ? IRQ_HANDLED : IRQ_NONE;
}

/*===========================================================================
 *                     9. NTB hardware driver initialization
 *===========================================================================
 */

/*
 * NTB API operations
 */
static const struct ntb_dev_ops idt_ntb_ops = {
        .port_number            = idt_ntb_port_number,
        .peer_port_count        = idt_ntb_peer_port_count,
        .peer_port_number       = idt_ntb_peer_port_number,
        .peer_port_idx          = idt_ntb_peer_port_idx,
        .link_is_up             = idt_ntb_link_is_up,
        .link_enable            = idt_ntb_link_enable,
        .link_disable           = idt_ntb_link_disable,
        .mw_count               = idt_ntb_mw_count,
        .mw_get_align           = idt_ntb_mw_get_align,
        .peer_mw_count          = idt_ntb_peer_mw_count,
        .peer_mw_get_addr       = idt_ntb_peer_mw_get_addr,
        .peer_mw_set_trans      = idt_ntb_peer_mw_set_trans,
        .peer_mw_clear_trans    = idt_ntb_peer_mw_clear_trans,
        .db_valid_mask          = idt_ntb_db_valid_mask,
        .db_read                = idt_ntb_db_read,
        .db_clear               = idt_ntb_db_clear,
        .db_read_mask           = idt_ntb_db_read_mask,
        .db_set_mask            = idt_ntb_db_set_mask,
        .db_clear_mask          = idt_ntb_db_clear_mask,
        .peer_db_set            = idt_ntb_peer_db_set,
        .msg_count              = idt_ntb_msg_count,
        .msg_inbits             = idt_ntb_msg_inbits,
        .msg_outbits            = idt_ntb_msg_outbits,
        .msg_read_sts           = idt_ntb_msg_read_sts,
        .msg_clear_sts          = idt_ntb_msg_clear_sts,
        .msg_set_mask           = idt_ntb_msg_set_mask,
        .msg_clear_mask         = idt_ntb_msg_clear_mask,
        .msg_read               = idt_ntb_msg_read,
        .peer_msg_write         = idt_ntb_peer_msg_write
};

/*
 * idt_register_device() - register IDT NTB device
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Return: zero on success, otherwise a negative error number.
 */
static int idt_register_device(struct idt_ntb_dev *ndev)
{
        int ret;

        /* Initialize the rest of NTB device structure and register it */
        ndev->ntb.ops = &idt_ntb_ops;
        ndev->ntb.topo = NTB_TOPO_SWITCH;

        ret = ntb_register_device(&ndev->ntb);
        if (ret != 0) {
                dev_err(&ndev->ntb.pdev->dev, "Failed to register NTB device");
                return ret;
        }

        dev_dbg(&ndev->ntb.pdev->dev, "NTB device successfully registered");

        return 0;
}

/*
 * idt_unregister_device() - unregister IDT NTB device
 * @ndev:       IDT NTB hardware driver descriptor
 */
static void idt_unregister_device(struct idt_ntb_dev *ndev)
{
        /* Just unregister the NTB device */
        ntb_unregister_device(&ndev->ntb);

        dev_dbg(&ndev->ntb.pdev->dev, "NTB device unregistered");
}

/*=============================================================================
 *                        10. DebugFS node initialization
 *=============================================================================
 */

static ssize_t idt_dbgfs_info_read(struct file *filp, char __user *ubuf,
                                   size_t count, loff_t *offp);

/*
 * Driver DebugFS info file operations
 */
static const struct file_operations idt_dbgfs_info_ops = {
        .owner = THIS_MODULE,
        .open = simple_open,
        .read = idt_dbgfs_info_read
};

/*
 * idt_dbgfs_info_read() - DebugFS read info node callback
 * @file:       File node descriptor.
 * @ubuf:       User-space buffer to put data to
 * @count:      Size of the buffer
 * @offp:       Offset within the buffer
 */
static ssize_t idt_dbgfs_info_read(struct file *filp, char __user *ubuf,
                                   size_t count, loff_t *offp)
{
        struct idt_ntb_dev *ndev = filp->private_data;
        unsigned char idx, pidx, cnt;
        unsigned long irqflags, mdeg;
        ssize_t ret = 0, off = 0;
        enum ntb_speed speed;
        enum ntb_width width;
        char *strbuf;
        size_t size;
        u32 data;

        /* Lets limit the buffer size the way the Intel/AMD drivers do */
        size = min_t(size_t, count, 0x1000U);

        /* Allocate the memory for the buffer */
        strbuf = kmalloc(size, GFP_KERNEL);
        if (strbuf == NULL)
                return -ENOMEM;

        /* Put the data into the string buffer */
        off += scnprintf(strbuf + off, size - off,
                "\n\t\tIDT NTB device Information:\n\n");

        /* General local device configurations */
        off += scnprintf(strbuf + off, size - off,
                "Local Port %hhu, Partition %hhu\n", ndev->port, ndev->part);

        /* Peer ports information */
        off += scnprintf(strbuf + off, size - off, "Peers:\n");
        for (idx = 0; idx < ndev->peer_cnt; idx++) {
                off += scnprintf(strbuf + off, size - off,
                        "\t%hhu. Port %hhu, Partition %hhu\n",
                        idx, ndev->peers[idx].port, ndev->peers[idx].part);
        }

        /* Links status */
        data = idt_ntb_link_is_up(&ndev->ntb, &speed, &width);
        off += scnprintf(strbuf + off, size - off,
                "NTB link status\t- 0x%08x, ", data);
        off += scnprintf(strbuf + off, size - off, "PCIe Gen %d x%d lanes\n",
                speed, width);

        /* Mapping table entries */
        off += scnprintf(strbuf + off, size - off, "NTB Mapping Table:\n");
        for (idx = 0; idx < IDT_MTBL_ENTRY_CNT; idx++) {
                spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
                idt_nt_write(ndev, IDT_NT_NTMTBLADDR, idx);
                data = idt_nt_read(ndev, IDT_NT_NTMTBLDATA);
                spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);

                /* Print valid entries only */
                if (data & IDT_NTMTBLDATA_VALID) {
                        off += scnprintf(strbuf + off, size - off,
                                "\t%hhu. Partition %d, Requester ID 0x%04x\n",
                                idx, GET_FIELD(NTMTBLDATA_PART, data),
                                GET_FIELD(NTMTBLDATA_REQID, data));
                }
        }
        off += scnprintf(strbuf + off, size - off, "\n");

        /* Outbound memory windows information */
        off += scnprintf(strbuf + off, size - off,
                "Outbound Memory Windows:\n");
        for (idx = 0; idx < ndev->mw_cnt; idx += cnt) {
                data = ndev->mws[idx].type;
                cnt = idt_get_mw_count(data);

                /* Print Memory Window information */
                if (data == IDT_MW_DIR)
                        off += scnprintf(strbuf + off, size - off,
                                "\t%hhu.\t", idx);
                else
                        off += scnprintf(strbuf + off, size - off,
                                "\t%hhu-%d.\t", idx, idx + cnt - 1);

                off += scnprintf(strbuf + off, size - off, "%s BAR%hhu, ",
                        idt_get_mw_name(data), ndev->mws[idx].bar);

                off += scnprintf(strbuf + off, size - off,
                        "Address align 0x%08llx, ", ndev->mws[idx].addr_align);

                off += scnprintf(strbuf + off, size - off,
                        "Size align 0x%08llx, Size max %llu\n",
                        ndev->mws[idx].size_align, ndev->mws[idx].size_max);
        }

        /* Inbound memory windows information */
        for (pidx = 0; pidx < ndev->peer_cnt; pidx++) {
                off += scnprintf(strbuf + off, size - off,
                        "Inbound Memory Windows for peer %hhu (Port %hhu):\n",
                        pidx, ndev->peers[pidx].port);

                /* Print Memory Windows information */
                for (idx = 0; idx < ndev->peers[pidx].mw_cnt; idx += cnt) {
                        data = ndev->peers[pidx].mws[idx].type;
                        cnt = idt_get_mw_count(data);

                        if (data == IDT_MW_DIR)
                                off += scnprintf(strbuf + off, size - off,
                                        "\t%hhu.\t", idx);
                        else
                                off += scnprintf(strbuf + off, size - off,
                                        "\t%hhu-%d.\t", idx, idx + cnt - 1);

                        off += scnprintf(strbuf + off, size - off,
                                "%s BAR%hhu, ", idt_get_mw_name(data),
                                ndev->peers[pidx].mws[idx].bar);

                        off += scnprintf(strbuf + off, size - off,
                                "Address align 0x%08llx, ",
                                ndev->peers[pidx].mws[idx].addr_align);

                        off += scnprintf(strbuf + off, size - off,
                                "Size align 0x%08llx, Size max %llu\n",
                                ndev->peers[pidx].mws[idx].size_align,
                                ndev->peers[pidx].mws[idx].size_max);
                }
        }
        off += scnprintf(strbuf + off, size - off, "\n");

        /* Doorbell information */
        data = idt_sw_read(ndev, IDT_SW_GDBELLSTS);
        off += scnprintf(strbuf + off, size - off,
                 "Global Doorbell state\t- 0x%08x\n", data);
        data = idt_ntb_db_read(&ndev->ntb);
        off += scnprintf(strbuf + off, size - off,
                 "Local  Doorbell state\t- 0x%08x\n", data);
        data = idt_nt_read(ndev, IDT_NT_INDBELLMSK);
        off += scnprintf(strbuf + off, size - off,
                 "Local  Doorbell mask\t- 0x%08x\n", data);
        off += scnprintf(strbuf + off, size - off, "\n");

        /* Messaging information */
        off += scnprintf(strbuf + off, size - off,
                 "Message event valid\t- 0x%08x\n", IDT_MSG_MASK);
        data = idt_ntb_msg_read_sts(&ndev->ntb);
        off += scnprintf(strbuf + off, size - off,
                 "Message event status\t- 0x%08x\n", data);
        data = idt_nt_read(ndev, IDT_NT_MSGSTSMSK);
        off += scnprintf(strbuf + off, size - off,
                 "Message event mask\t- 0x%08x\n", data);
        off += scnprintf(strbuf + off, size - off,
                 "Message data:\n");
        for (idx = 0; idx < IDT_MSG_CNT; idx++) {
                int src;
                data = idt_ntb_msg_read(&ndev->ntb, &src, idx);
                off += scnprintf(strbuf + off, size - off,
                        "\t%hhu. 0x%08x from peer %d (Port %hhu)\n",
                        idx, data, src, ndev->peers[src].port);
        }
        off += scnprintf(strbuf + off, size - off, "\n");

        /* Current temperature */
        idt_read_temp(ndev, IDT_TEMP_CUR, &mdeg);
        off += scnprintf(strbuf + off, size - off,
                "Switch temperature\t\t- %hhd.%hhuC\n",
                idt_get_deg(mdeg), idt_get_deg_frac(mdeg));

        /* Copy the buffer to the User Space */
        ret = simple_read_from_buffer(ubuf, count, offp, strbuf, off);
        kfree(strbuf);

        return ret;
}

/*
 * idt_init_dbgfs() - initialize DebugFS node
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Return: zero on success, otherwise a negative error number.
 */
static int idt_init_dbgfs(struct idt_ntb_dev *ndev)
{
        char devname[64];

        /* If the top directory is not created then do nothing */
        if (IS_ERR_OR_NULL(dbgfs_topdir)) {
                dev_info(&ndev->ntb.pdev->dev, "Top DebugFS directory absent");
                return PTR_ERR_OR_ZERO(dbgfs_topdir);
        }

        /* Create the info file node */
        snprintf(devname, 64, "info:%s", pci_name(ndev->ntb.pdev));
        ndev->dbgfs_info = debugfs_create_file(devname, 0400, dbgfs_topdir,
                ndev, &idt_dbgfs_info_ops);
        if (IS_ERR(ndev->dbgfs_info)) {
                dev_dbg(&ndev->ntb.pdev->dev, "Failed to create DebugFS node");
                return PTR_ERR(ndev->dbgfs_info);
        }

        dev_dbg(&ndev->ntb.pdev->dev, "NTB device DebugFS node created");

        return 0;
}

/*
 * idt_deinit_dbgfs() - deinitialize DebugFS node
 * @ndev:       IDT NTB hardware driver descriptor
 *
 * Just discard the info node from DebugFS
 */
static void idt_deinit_dbgfs(struct idt_ntb_dev *ndev)
{
        debugfs_remove(ndev->dbgfs_info);

        dev_dbg(&ndev->ntb.pdev->dev, "NTB device DebugFS node discarded");
}

/*=============================================================================
 *                     11. Basic PCIe device initialization
 *=============================================================================
 */

/*
 * idt_check_setup() - Check whether the IDT PCIe-switch is properly
 *                     pre-initialized
 * @pdev:       Pointer to the PCI device descriptor
 *
 * Return: zero on success, otherwise a negative error number.
 */
static int idt_check_setup(struct pci_dev *pdev)
{
        u32 data;
        int ret;

        /* Read the BARSETUP0 */
        ret = pci_read_config_dword(pdev, IDT_NT_BARSETUP0, &data);
        if (ret != 0) {
                dev_err(&pdev->dev,
                        "Failed to read BARSETUP0 config register");
                return ret;
        }

        /* Check whether the BAR0 register is enabled to be of config space */
        if (!(data & IDT_BARSETUP_EN) || !(data & IDT_BARSETUP_MODE_CFG)) {
                dev_err(&pdev->dev, "BAR0 doesn't map config space");
                return -EINVAL;
        }

        /* Configuration space BAR0 must have certain size */
        if ((data & IDT_BARSETUP_SIZE_MASK) != IDT_BARSETUP_SIZE_CFG) {
                dev_err(&pdev->dev, "Invalid size of config space");
                return -EINVAL;
        }

        dev_dbg(&pdev->dev, "NTB device pre-initialized correctly");

        return 0;
}

/*
 * Create the IDT PCIe-switch driver descriptor
 * @pdev:       Pointer to the PCI device descriptor
 * @id:         IDT PCIe-device configuration
 *
 * It just allocates a memory for IDT PCIe-switch device structure and
 * initializes some commonly used fields.
 *
 * No need of release method, since managed device resource is used for
 * memory allocation.
 *
 * Return: pointer to the descriptor, otherwise a negative error number.
 */
static struct idt_ntb_dev *idt_create_dev(struct pci_dev *pdev,
                                          const struct pci_device_id *id)
{
        struct idt_ntb_dev *ndev;

        /* Allocate memory for the IDT PCIe-device descriptor */
        ndev = devm_kzalloc(&pdev->dev, sizeof(*ndev), GFP_KERNEL);
        if (!ndev) {
                dev_err(&pdev->dev, "Memory allocation failed for descriptor");
                return ERR_PTR(-ENOMEM);
        }

        /* Save the IDT PCIe-switch ports configuration */
        ndev->swcfg = (struct idt_89hpes_cfg *)id->driver_data;
        /* Save the PCI-device pointer inside the NTB device structure */
        ndev->ntb.pdev = pdev;

        /* Initialize spin locker of Doorbell, Message and GASA registers */
        spin_lock_init(&ndev->db_mask_lock);
        spin_lock_init(&ndev->msg_mask_lock);
        spin_lock_init(&ndev->gasa_lock);

        dev_info(&pdev->dev, "IDT %s discovered", ndev->swcfg->name);

        dev_dbg(&pdev->dev, "NTB device descriptor created");

        return ndev;
}

/*
 * idt_init_pci() - initialize the basic PCI-related subsystem
 * @ndev:       Pointer to the IDT PCIe-switch driver descriptor
 *
 * Managed device resources will be freed automatically in case of failure or
 * driver detachment.
 *
 * Return: zero on success, otherwise negative error number.
 */
static int idt_init_pci(struct idt_ntb_dev *ndev)
{
        struct pci_dev *pdev = ndev->ntb.pdev;
        int ret;

        /* Initialize the bit mask of PCI/NTB DMA */
        ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
        if (ret != 0) {
                ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
                if (ret != 0) {
                        dev_err(&pdev->dev, "Failed to set DMA bit mask\n");
                        return ret;
                }
                dev_warn(&pdev->dev, "Cannot set DMA highmem bit mask\n");
        }

        /*
         * The PCI core enables device error reporting. It's not critical to
         * have AER disabled in the kernel.
         *
         * Cleanup nonfatal error status before getting to init.
         */
        pci_aer_clear_nonfatal_status(pdev);

        /* First enable the PCI device */
        ret = pcim_enable_device(pdev);
        if (ret != 0) {
                dev_err(&pdev->dev, "Failed to enable PCIe device\n");
                return ret;
        }

        /*
         * Enable the bus mastering, which effectively enables MSI IRQs and
         * Request TLPs translation
         */
        pci_set_master(pdev);

        /* Request all BARs resources */
        ret = pcim_request_all_regions(pdev, NTB_NAME);
        if (ret != 0) {
                dev_err(&pdev->dev, "Failed to request resources\n");
                goto err_clear_master;
        }

        /* ioremap BAR0 - PCI configuration space */
        ndev->cfgspc = pcim_iomap(pdev, 0, 0);
        if (!ndev->cfgspc) {
                dev_err(&pdev->dev, "Failed to ioremap BAR 0\n");
                ret = -ENOMEM;
                goto err_clear_master;
        }

        /* Put the IDT driver data pointer to the PCI-device private pointer */
        pci_set_drvdata(pdev, ndev);

        dev_dbg(&pdev->dev, "NT-function PCIe interface initialized");

        return 0;

err_clear_master:
        pci_clear_master(pdev);

        return ret;
}

/*
 * idt_deinit_pci() - deinitialize the basic PCI-related subsystem
 * @ndev:       Pointer to the IDT PCIe-switch driver descriptor
 *
 * Managed resources will be freed on the driver detachment
 */
static void idt_deinit_pci(struct idt_ntb_dev *ndev)
{
        struct pci_dev *pdev = ndev->ntb.pdev;

        /* Clean up the PCI-device private data pointer */
        pci_set_drvdata(pdev, NULL);

        /* Clear the bus master disabling the Request TLPs translation */
        pci_clear_master(pdev);

        dev_dbg(&pdev->dev, "NT-function PCIe interface cleared");
}

/*===========================================================================
 *                       12. PCI bus callback functions
 *===========================================================================
 */

/*
 * idt_pci_probe() - PCI device probe callback
 * @pdev:       Pointer to PCI device structure
 * @id:         PCIe device custom descriptor
 *
 * Return: zero on success, otherwise negative error number
 */
static int idt_pci_probe(struct pci_dev *pdev,
                         const struct pci_device_id *id)
{
        struct idt_ntb_dev *ndev;
        int ret;

        /* Check whether IDT PCIe-switch is properly pre-initialized */
        ret = idt_check_setup(pdev);
        if (ret != 0)
                return ret;

        /* Allocate the memory for IDT NTB device data */
        ndev = idt_create_dev(pdev, id);
        if (IS_ERR(ndev))
                return PTR_ERR(ndev);

        /* Initialize the basic PCI subsystem of the device */
        ret = idt_init_pci(ndev);
        if (ret != 0)
                return ret;

        /* Scan ports of the IDT PCIe-switch */
        (void)idt_scan_ports(ndev);

        /* Initialize NTB link events subsystem */
        idt_init_link(ndev);

        /* Initialize MWs subsystem */
        ret = idt_init_mws(ndev);
        if (ret != 0)
                goto err_deinit_link;

        /* Initialize Messaging subsystem */
        idt_init_msg(ndev);

        /* Initialize hwmon interface */
        idt_init_temp(ndev);

        /* Initialize IDT interrupts handler */
        ret = idt_init_isr(ndev);
        if (ret != 0)
                goto err_deinit_link;

        /* Register IDT NTB devices on the NTB bus */
        ret = idt_register_device(ndev);
        if (ret != 0)
                goto err_deinit_isr;

        /* Initialize DebugFS info node */
        (void)idt_init_dbgfs(ndev);

        /* IDT PCIe-switch NTB driver is finally initialized */
        dev_info(&pdev->dev, "IDT NTB device is ready");

        /* May the force be with us... */
        return 0;

err_deinit_isr:
        idt_deinit_isr(ndev);
err_deinit_link:
        idt_deinit_link(ndev);
        idt_deinit_pci(ndev);

        return ret;
}

/*
 * idt_pci_probe() - PCI device remove callback
 * @pdev:       Pointer to PCI device structure
 */
static void idt_pci_remove(struct pci_dev *pdev)
{
        struct idt_ntb_dev *ndev = pci_get_drvdata(pdev);

        /* Deinit the DebugFS node */
        idt_deinit_dbgfs(ndev);

        /* Unregister NTB device */
        idt_unregister_device(ndev);

        /* Stop the interrupts handling */
        idt_deinit_isr(ndev);

        /* Deinitialize link event subsystem */
        idt_deinit_link(ndev);

        /* Deinit basic PCI subsystem */
        idt_deinit_pci(ndev);

        /* IDT PCIe-switch NTB driver is finally initialized */
        dev_info(&pdev->dev, "IDT NTB device is removed");

        /* Sayonara... */
}

/*
 * IDT PCIe-switch models ports configuration structures
 */
static const struct idt_89hpes_cfg idt_89hpes24nt6ag2_config = {
        .name = "89HPES24NT6AG2",
        .port_cnt = 6, .ports = {0, 2, 4, 6, 8, 12}
};
static const struct idt_89hpes_cfg idt_89hpes32nt8ag2_config = {
        .name = "89HPES32NT8AG2",
        .port_cnt = 8, .ports = {0, 2, 4, 6, 8, 12, 16, 20}
};
static const struct idt_89hpes_cfg idt_89hpes32nt8bg2_config = {
        .name = "89HPES32NT8BG2",
        .port_cnt = 8, .ports = {0, 2, 4, 6, 8, 12, 16, 20}
};
static const struct idt_89hpes_cfg idt_89hpes12nt12g2_config = {
        .name = "89HPES12NT12G2",
        .port_cnt = 3, .ports = {0, 8, 16}
};
static const struct idt_89hpes_cfg idt_89hpes16nt16g2_config = {
        .name = "89HPES16NT16G2",
        .port_cnt = 4, .ports = {0, 8, 12, 16}
};
static const struct idt_89hpes_cfg idt_89hpes24nt24g2_config = {
        .name = "89HPES24NT24G2",
        .port_cnt = 8, .ports = {0, 2, 4, 6, 8, 12, 16, 20}
};
static const struct idt_89hpes_cfg idt_89hpes32nt24ag2_config = {
        .name = "89HPES32NT24AG2",
        .port_cnt = 8, .ports = {0, 2, 4, 6, 8, 12, 16, 20}
};
static const struct idt_89hpes_cfg idt_89hpes32nt24bg2_config = {
        .name = "89HPES32NT24BG2",
        .port_cnt = 8, .ports = {0, 2, 4, 6, 8, 12, 16, 20}
};

/*
 * PCI-ids table of the supported IDT PCIe-switch devices
 */
static const struct pci_device_id idt_pci_tbl[] = {
        {IDT_PCI_DEVICE_IDS(89HPES24NT6AG2,  idt_89hpes24nt6ag2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES32NT8AG2,  idt_89hpes32nt8ag2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES32NT8BG2,  idt_89hpes32nt8bg2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES12NT12G2,  idt_89hpes12nt12g2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES16NT16G2,  idt_89hpes16nt16g2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES24NT24G2,  idt_89hpes24nt24g2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES32NT24AG2, idt_89hpes32nt24ag2_config)},
        {IDT_PCI_DEVICE_IDS(89HPES32NT24BG2, idt_89hpes32nt24bg2_config)},
        {0}
};
MODULE_DEVICE_TABLE(pci, idt_pci_tbl);

/*
 * IDT PCIe-switch NT-function device driver structure definition
 */
static struct pci_driver idt_pci_driver = {
        .name           = KBUILD_MODNAME,
        .probe          = idt_pci_probe,
        .remove         = idt_pci_remove,
        .id_table       = idt_pci_tbl,
};

static int __init idt_pci_driver_init(void)
{
        int ret;
        pr_info("%s %s\n", NTB_DESC, NTB_VER);

        /* Create the top DebugFS directory if the FS is initialized */
        if (debugfs_initialized())
                dbgfs_topdir = debugfs_create_dir(KBUILD_MODNAME, NULL);

        /* Register the NTB hardware driver to handle the PCI device */
        ret = pci_register_driver(&idt_pci_driver);
        if (ret)
                debugfs_remove_recursive(dbgfs_topdir);

        return ret;
}
module_init(idt_pci_driver_init);

static void __exit idt_pci_driver_exit(void)
{
        /* Unregister the NTB hardware driver */
        pci_unregister_driver(&idt_pci_driver);

        /* Discard the top DebugFS directory */
        debugfs_remove_recursive(dbgfs_topdir);
}
module_exit(idt_pci_driver_exit);