/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2005-2009, 2010 Cavium Networks
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/msi.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>

#include <asm/octeon/octeon.h>
#include <asm/octeon/cvmx-npi-defs.h>
#include <asm/octeon/cvmx-pci-defs.h>
#include <asm/octeon/cvmx-npei-defs.h>
#include <asm/octeon/cvmx-sli-defs.h>
#include <asm/octeon/cvmx-pexp-defs.h>
#include <asm/octeon/pci-octeon.h>

/*
 * Each bit in msi_free_irq_bitmask represents a MSI interrupt that is
 * in use.
 */
static u64 msi_free_irq_bitmask[4];

/*
 * Each bit in msi_multiple_irq_bitmask tells that the device using
 * this bit in msi_free_irq_bitmask is also using the next bit. This
 * is used so we can disable all of the MSI interrupts when a device
 * uses multiple.
 */
static u64 msi_multiple_irq_bitmask[4];

/*
 * This lock controls updates to msi_free_irq_bitmask and
 * msi_multiple_irq_bitmask.
 */
static DEFINE_SPINLOCK(msi_free_irq_bitmask_lock);

/*
 * Number of MSI IRQs used. This variable is set up in
 * the module init time.
 */
static int msi_irq_size;

/**
 * arch_setup_msi_irq() - setup MSI IRQs for a device
 * @dev:    Device requesting MSI interrupts
 * @desc:   MSI descriptor
 *
 * Called when a driver requests MSI interrupts instead of the
 * legacy INT A-D. This routine will allocate multiple interrupts
 * for MSI devices that support them. A device can override this by
 * programming the MSI control bits [6:4] before calling
 * pci_enable_msi().
 *
 * Return: %0 on success, non-%0 on error.
 */
int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
{
        struct msi_msg msg;
        u16 control;
        int configured_private_bits;
        int request_private_bits;
        int irq = 0;
        int irq_step;
        u64 search_mask;
        int index;

        if (desc->pci.msi_attrib.is_msix)
                return -EINVAL;

        /*
         * Read the MSI config to figure out how many IRQs this device
         * wants.  Most devices only want 1, which will give
         * configured_private_bits and request_private_bits equal 0.
         */
        pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);

        /*
         * If the number of private bits has been configured then use
         * that value instead of the requested number. This gives the
         * driver the chance to override the number of interrupts
         * before calling pci_enable_msi().
         */
        configured_private_bits = (control & PCI_MSI_FLAGS_QSIZE) >> 4;
        if (configured_private_bits == 0) {
                /* Nothing is configured, so use the hardware requested size */
                request_private_bits = (control & PCI_MSI_FLAGS_QMASK) >> 1;
        } else {
                /*
                 * Use the number of configured bits, assuming the
                 * driver wanted to override the hardware request
                 * value.
                 */
                request_private_bits = configured_private_bits;
        }

        /*
         * The PCI 2.3 spec mandates that there are at most 32
         * interrupts. If this device asks for more, only give it one.
         */
        if (request_private_bits > 5)
                request_private_bits = 0;

try_only_one:
        /*
         * The IRQs have to be aligned on a power of two based on the
         * number being requested.
         */
        irq_step = 1 << request_private_bits;

        /* Mask with one bit for each IRQ */
        search_mask = (1 << irq_step) - 1;

        /*
         * We're going to search msi_free_irq_bitmask_lock for zero
         * bits. This represents an MSI interrupt number that isn't in
         * use.
         */
        spin_lock(&msi_free_irq_bitmask_lock);
        for (index = 0; index < msi_irq_size/64; index++) {
                for (irq = 0; irq < 64; irq += irq_step) {
                        if ((msi_free_irq_bitmask[index] & (search_mask << irq)) == 0) {
                                msi_free_irq_bitmask[index] |= search_mask << irq;
                                msi_multiple_irq_bitmask[index] |= (search_mask >> 1) << irq;
                                goto msi_irq_allocated;
                        }
                }
        }
msi_irq_allocated:
        spin_unlock(&msi_free_irq_bitmask_lock);

        /* Make sure the search for available interrupts didn't fail */
        if (irq >= 64) {
                if (request_private_bits) {
                        pr_err("arch_setup_msi_irq: Unable to find %d free interrupts, trying just one",
                               1 << request_private_bits);
                        request_private_bits = 0;
                        goto try_only_one;
                } else
                        panic("arch_setup_msi_irq: Unable to find a free MSI interrupt");
        }

        /* MSI interrupts start at logical IRQ OCTEON_IRQ_MSI_BIT0 */
        irq += index*64;
        irq += OCTEON_IRQ_MSI_BIT0;

        switch (octeon_dma_bar_type) {
        case OCTEON_DMA_BAR_TYPE_SMALL:
                /* When not using big bar, Bar 0 is based at 128MB */
                msg.address_lo =
                        ((128ul << 20) + CVMX_PCI_MSI_RCV) & 0xffffffff;
                msg.address_hi = ((128ul << 20) + CVMX_PCI_MSI_RCV) >> 32;
                break;
        case OCTEON_DMA_BAR_TYPE_BIG:
                /* When using big bar, Bar 0 is based at 0 */
                msg.address_lo = (0 + CVMX_PCI_MSI_RCV) & 0xffffffff;
                msg.address_hi = (0 + CVMX_PCI_MSI_RCV) >> 32;
                break;
        case OCTEON_DMA_BAR_TYPE_PCIE:
                /* When using PCIe, Bar 0 is based at 0 */
                /* FIXME CVMX_NPEI_MSI_RCV* other than 0? */
                msg.address_lo = (0 + CVMX_NPEI_PCIE_MSI_RCV) & 0xffffffff;
                msg.address_hi = (0 + CVMX_NPEI_PCIE_MSI_RCV) >> 32;
                break;
        case OCTEON_DMA_BAR_TYPE_PCIE2:
                /* When using PCIe2, Bar 0 is based at 0 */
                msg.address_lo = (0 + CVMX_SLI_PCIE_MSI_RCV) & 0xffffffff;
                msg.address_hi = (0 + CVMX_SLI_PCIE_MSI_RCV) >> 32;
                break;
        default:
                panic("arch_setup_msi_irq: Invalid octeon_dma_bar_type");
        }
        msg.data = irq - OCTEON_IRQ_MSI_BIT0;

        /* Update the number of IRQs the device has available to it */
        control &= ~PCI_MSI_FLAGS_QSIZE;
        control |= request_private_bits << 4;
        pci_write_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, control);

        irq_set_msi_desc(irq, desc);
        pci_write_msi_msg(irq, &msg);
        return 0;
}

/**
 * arch_teardown_msi_irq() - release MSI IRQs for a device
 * @irq:    The devices first irq number. There may be multiple in sequence.
 *
 * Called when a device no longer needs its MSI interrupts. All
 * MSI interrupts for the device are freed.
 */
void arch_teardown_msi_irq(unsigned int irq)
{
        int number_irqs;
        u64 bitmask;
        int index = 0;
        int irq0;

        if ((irq < OCTEON_IRQ_MSI_BIT0)
                || (irq > msi_irq_size + OCTEON_IRQ_MSI_BIT0))
                panic("arch_teardown_msi_irq: Attempted to teardown illegal "
                      "MSI interrupt (%d)", irq);

        irq -= OCTEON_IRQ_MSI_BIT0;
        index = irq / 64;
        irq0 = irq % 64;

        /*
         * Count the number of IRQs we need to free by looking at the
         * msi_multiple_irq_bitmask. Each bit set means that the next
         * IRQ is also owned by this device.
         */
        number_irqs = 0;
        while ((irq0 + number_irqs < 64) &&
               (msi_multiple_irq_bitmask[index]
                & (1ull << (irq0 + number_irqs))))
                number_irqs++;
        number_irqs++;
        /* Mask with one bit for each IRQ */
        bitmask = (1 << number_irqs) - 1;
        /* Shift the mask to the correct bit location */
        bitmask <<= irq0;
        if ((msi_free_irq_bitmask[index] & bitmask) != bitmask)
                panic("arch_teardown_msi_irq: Attempted to teardown MSI "
                      "interrupt (%d) not in use", irq);

        /* Checks are done, update the in use bitmask */
        spin_lock(&msi_free_irq_bitmask_lock);
        msi_free_irq_bitmask[index] &= ~bitmask;
        msi_multiple_irq_bitmask[index] &= ~bitmask;
        spin_unlock(&msi_free_irq_bitmask_lock);
}

static DEFINE_RAW_SPINLOCK(octeon_irq_msi_lock);

static u64 msi_rcv_reg[4];
static u64 mis_ena_reg[4];

static void octeon_irq_msi_enable_pcie(struct irq_data *data)
{
        u64 en;
        unsigned long flags;
        int msi_number = data->irq - OCTEON_IRQ_MSI_BIT0;
        int irq_index = msi_number >> 6;
        int irq_bit = msi_number & 0x3f;

        raw_spin_lock_irqsave(&octeon_irq_msi_lock, flags);
        en = cvmx_read_csr(mis_ena_reg[irq_index]);
        en |= 1ull << irq_bit;
        cvmx_write_csr(mis_ena_reg[irq_index], en);
        cvmx_read_csr(mis_ena_reg[irq_index]);
        raw_spin_unlock_irqrestore(&octeon_irq_msi_lock, flags);
}

static void octeon_irq_msi_disable_pcie(struct irq_data *data)
{
        u64 en;
        unsigned long flags;
        int msi_number = data->irq - OCTEON_IRQ_MSI_BIT0;
        int irq_index = msi_number >> 6;
        int irq_bit = msi_number & 0x3f;

        raw_spin_lock_irqsave(&octeon_irq_msi_lock, flags);
        en = cvmx_read_csr(mis_ena_reg[irq_index]);
        en &= ~(1ull << irq_bit);
        cvmx_write_csr(mis_ena_reg[irq_index], en);
        cvmx_read_csr(mis_ena_reg[irq_index]);
        raw_spin_unlock_irqrestore(&octeon_irq_msi_lock, flags);
}

static struct irq_chip octeon_irq_chip_msi_pcie = {
        .name = "MSI",
        .irq_enable = octeon_irq_msi_enable_pcie,
        .irq_disable = octeon_irq_msi_disable_pcie,
};

static void octeon_irq_msi_enable_pci(struct irq_data *data)
{
        /*
         * Octeon PCI doesn't have the ability to mask/unmask MSI
         * interrupts individually. Instead of masking/unmasking them
         * in groups of 16, we simple assume MSI devices are well
         * behaved. MSI interrupts are always enable and the ACK is
         * assumed to be enough
         */
}

static void octeon_irq_msi_disable_pci(struct irq_data *data)
{
        /* See comment in enable */
}

static struct irq_chip octeon_irq_chip_msi_pci = {
        .name = "MSI",
        .irq_enable = octeon_irq_msi_enable_pci,
        .irq_disable = octeon_irq_msi_disable_pci,
};

/*
 * Called by the interrupt handling code when an MSI interrupt
 * occurs.
 */
static irqreturn_t __octeon_msi_do_interrupt(int index, u64 msi_bits)
{
        int irq;
        int bit;

        bit = fls64(msi_bits);
        if (bit) {
                bit--;
                /* Acknowledge it first. */
                cvmx_write_csr(msi_rcv_reg[index], 1ull << bit);

                irq = bit + OCTEON_IRQ_MSI_BIT0 + 64 * index;
                do_IRQ(irq);
                return IRQ_HANDLED;
        }
        return IRQ_NONE;
}

#define OCTEON_MSI_INT_HANDLER_X(x)                                     \
static irqreturn_t octeon_msi_interrupt##x(int cpl, void *dev_id)       \
{                                                                       \
        u64 msi_bits = cvmx_read_csr(msi_rcv_reg[(x)]);                 \
        return __octeon_msi_do_interrupt((x), msi_bits);                \
}

/*
 * Create octeon_msi_interrupt{0-3} function body
 */
OCTEON_MSI_INT_HANDLER_X(0);
OCTEON_MSI_INT_HANDLER_X(1);
OCTEON_MSI_INT_HANDLER_X(2);
OCTEON_MSI_INT_HANDLER_X(3);

/*
 * Initializes the MSI interrupt handling code
 */
int __init octeon_msi_initialize(void)
{
        int irq;
        struct irq_chip *msi;

        if (octeon_dma_bar_type == OCTEON_DMA_BAR_TYPE_INVALID) {
                return 0;
        } else if (octeon_dma_bar_type == OCTEON_DMA_BAR_TYPE_PCIE) {
                msi_rcv_reg[0] = CVMX_PEXP_NPEI_MSI_RCV0;
                msi_rcv_reg[1] = CVMX_PEXP_NPEI_MSI_RCV1;
                msi_rcv_reg[2] = CVMX_PEXP_NPEI_MSI_RCV2;
                msi_rcv_reg[3] = CVMX_PEXP_NPEI_MSI_RCV3;
                mis_ena_reg[0] = CVMX_PEXP_NPEI_MSI_ENB0;
                mis_ena_reg[1] = CVMX_PEXP_NPEI_MSI_ENB1;
                mis_ena_reg[2] = CVMX_PEXP_NPEI_MSI_ENB2;
                mis_ena_reg[3] = CVMX_PEXP_NPEI_MSI_ENB3;
                msi = &octeon_irq_chip_msi_pcie;
        } else {
                msi_rcv_reg[0] = CVMX_NPI_NPI_MSI_RCV;
#define INVALID_GENERATE_ADE 0x8700000000000000ULL;
                msi_rcv_reg[1] = INVALID_GENERATE_ADE;
                msi_rcv_reg[2] = INVALID_GENERATE_ADE;
                msi_rcv_reg[3] = INVALID_GENERATE_ADE;
                mis_ena_reg[0] = INVALID_GENERATE_ADE;
                mis_ena_reg[1] = INVALID_GENERATE_ADE;
                mis_ena_reg[2] = INVALID_GENERATE_ADE;
                mis_ena_reg[3] = INVALID_GENERATE_ADE;
                msi = &octeon_irq_chip_msi_pci;
        }

        for (irq = OCTEON_IRQ_MSI_BIT0; irq <= OCTEON_IRQ_MSI_LAST; irq++)
                irq_set_chip_and_handler(irq, msi, handle_simple_irq);

        if (octeon_has_feature(OCTEON_FEATURE_PCIE)) {
                if (request_irq(OCTEON_IRQ_PCI_MSI0, octeon_msi_interrupt0,
                                0, "MSI[0:63]", octeon_msi_interrupt0))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI0) failed");

                if (request_irq(OCTEON_IRQ_PCI_MSI1, octeon_msi_interrupt1,
                                0, "MSI[64:127]", octeon_msi_interrupt1))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI1) failed");

                if (request_irq(OCTEON_IRQ_PCI_MSI2, octeon_msi_interrupt2,
                                0, "MSI[127:191]", octeon_msi_interrupt2))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI2) failed");

                if (request_irq(OCTEON_IRQ_PCI_MSI3, octeon_msi_interrupt3,
                                0, "MSI[192:255]", octeon_msi_interrupt3))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI3) failed");

                msi_irq_size = 256;
        } else if (octeon_is_pci_host()) {
                if (request_irq(OCTEON_IRQ_PCI_MSI0, octeon_msi_interrupt0,
                                0, "MSI[0:15]", octeon_msi_interrupt0))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI0) failed");

                if (request_irq(OCTEON_IRQ_PCI_MSI1, octeon_msi_interrupt0,
                                0, "MSI[16:31]", octeon_msi_interrupt0))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI1) failed");

                if (request_irq(OCTEON_IRQ_PCI_MSI2, octeon_msi_interrupt0,
                                0, "MSI[32:47]", octeon_msi_interrupt0))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI2) failed");

                if (request_irq(OCTEON_IRQ_PCI_MSI3, octeon_msi_interrupt0,
                                0, "MSI[48:63]", octeon_msi_interrupt0))
                        panic("request_irq(OCTEON_IRQ_PCI_MSI3) failed");
                msi_irq_size = 64;
        }
        return 0;
}
subsys_initcall(octeon_msi_initialize);