// SPDX-License-Identifier: GPL-2.0
/*
 * Generic SH7786 PCI-Express operations.
 *
 *  Copyright (C) 2009 - 2010  Paul Mundt
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include "pcie-sh7786.h"

enum {
        PCI_ACCESS_READ,
        PCI_ACCESS_WRITE,
};

static int sh7786_pcie_config_access(unsigned char access_type,
                struct pci_bus *bus, unsigned int devfn, int where, u32 *data)
{
        struct pci_channel *chan = bus->sysdata;
        int dev, func, type, reg;

        dev = PCI_SLOT(devfn);
        func = PCI_FUNC(devfn);
        type = !!bus->parent;
        reg = where & ~3;

        if (bus->number > 255 || dev > 31 || func > 7)
                return PCIBIOS_FUNC_NOT_SUPPORTED;

        /*
         * While each channel has its own memory-mapped extended config
         * space, it's generally only accessible when in endpoint mode.
         * When in root complex mode, the controller is unable to target
         * itself with either type 0 or type 1 accesses, and indeed, any
         * controller initiated target transfer to its own config space
         * result in a completer abort.
         *
         * Each channel effectively only supports a single device, but as
         * the same channel <-> device access works for any PCI_SLOT()
         * value, we cheat a bit here and bind the controller's config
         * space to devfn 0 in order to enable self-enumeration. In this
         * case the regular PAR/PDR path is sidelined and the mangled
         * config access itself is initiated as a SuperHyway transaction.
         */
        if (pci_is_root_bus(bus)) {
                if (dev == 0) {
                        if (access_type == PCI_ACCESS_READ)
                                *data = pci_read_reg(chan, PCI_REG(reg));
                        else
                                pci_write_reg(chan, *data, PCI_REG(reg));

                        return PCIBIOS_SUCCESSFUL;
                } else if (dev > 1)
                        return PCIBIOS_DEVICE_NOT_FOUND;
        }

        /* Clear errors */
        pci_write_reg(chan, pci_read_reg(chan, SH4A_PCIEERRFR), SH4A_PCIEERRFR);

        /* Set the PIO address */
        pci_write_reg(chan, (bus->number << 24) | (dev << 19) |
                                (func << 16) | reg, SH4A_PCIEPAR);

        /* Enable the configuration access */
        pci_write_reg(chan, (1 << 31) | (type << 8), SH4A_PCIEPCTLR);

        /* Check for errors */
        if (pci_read_reg(chan, SH4A_PCIEERRFR) & 0x10)
                return PCIBIOS_DEVICE_NOT_FOUND;

        /* Check for master and target aborts */
        if (pci_read_reg(chan, SH4A_PCIEPCICONF1) & ((1 << 29) | (1 << 28)))
                return PCIBIOS_DEVICE_NOT_FOUND;

        if (access_type == PCI_ACCESS_READ)
                *data = pci_read_reg(chan, SH4A_PCIEPDR);
        else
                pci_write_reg(chan, *data, SH4A_PCIEPDR);

        /* Disable the configuration access */
        pci_write_reg(chan, 0, SH4A_PCIEPCTLR);

        return PCIBIOS_SUCCESSFUL;
}

static int sh7786_pcie_read(struct pci_bus *bus, unsigned int devfn,
                            int where, int size, u32 *val)
{
        unsigned long flags;
        int ret;
        u32 data;

        if ((size == 2) && (where & 1))
                return PCIBIOS_BAD_REGISTER_NUMBER;
        else if ((size == 4) && (where & 3))
                return PCIBIOS_BAD_REGISTER_NUMBER;

        raw_spin_lock_irqsave(&pci_config_lock, flags);
        ret = sh7786_pcie_config_access(PCI_ACCESS_READ, bus,
                                        devfn, where, &data);
        if (ret != PCIBIOS_SUCCESSFUL) {
                *val = 0xffffffff;
                goto out;
        }

        if (size == 1)
                *val = (data >> ((where & 3) << 3)) & 0xff;
        else if (size == 2)
                *val = (data >> ((where & 2) << 3)) & 0xffff;
        else
                *val = data;

        dev_dbg(&bus->dev, "pcie-config-read: bus=%3d devfn=0x%04x "
                "where=0x%04x size=%d val=0x%08lx\n", bus->number,
                devfn, where, size, (unsigned long)*val);

out:
        raw_spin_unlock_irqrestore(&pci_config_lock, flags);
        return ret;
}

static int sh7786_pcie_write(struct pci_bus *bus, unsigned int devfn,
                             int where, int size, u32 val)
{
        unsigned long flags;
        int shift, ret;
        u32 data;

        if ((size == 2) && (where & 1))
                return PCIBIOS_BAD_REGISTER_NUMBER;
        else if ((size == 4) && (where & 3))
                return PCIBIOS_BAD_REGISTER_NUMBER;

        raw_spin_lock_irqsave(&pci_config_lock, flags);
        ret = sh7786_pcie_config_access(PCI_ACCESS_READ, bus,
                                        devfn, where, &data);
        if (ret != PCIBIOS_SUCCESSFUL)
                goto out;

        dev_dbg(&bus->dev, "pcie-config-write: bus=%3d devfn=0x%04x "
                "where=0x%04x size=%d val=%08lx\n", bus->number,
                devfn, where, size, (unsigned long)val);

        if (size == 1) {
                shift = (where & 3) << 3;
                data &= ~(0xff << shift);
                data |= ((val & 0xff) << shift);
        } else if (size == 2) {
                shift = (where & 2) << 3;
                data &= ~(0xffff << shift);
                data |= ((val & 0xffff) << shift);
        } else
                data = val;

        ret = sh7786_pcie_config_access(PCI_ACCESS_WRITE, bus,
                                        devfn, where, &data);
out:
        raw_spin_unlock_irqrestore(&pci_config_lock, flags);
        return ret;
}

struct pci_ops sh7786_pci_ops = {
        .read   = sh7786_pcie_read,
        .write  = sh7786_pcie_write,
};