/*
 * MSI support for PPC4xx SoCs using High Speed Transfer Assist (HSTA) for
 * generation of the interrupt.
 *
 * Copyright © 2013 Alistair Popple <alistair@popple.id.au> IBM Corporation
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/msi.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/pci.h>
#include <linux/semaphore.h>
#include <asm/msi_bitmap.h>
#include <asm/ppc-pci.h>

struct ppc4xx_hsta_msi {
        struct device *dev;

        /* The ioremapped HSTA MSI IO space */
        u32 __iomem *data;

        /* Physical address of HSTA MSI IO space */
        u64 address;
        struct msi_bitmap bmp;

        /* An array mapping offsets to hardware IRQs */
        int *irq_map;

        /* Number of hwirqs supported */
        int irq_count;
};
static struct ppc4xx_hsta_msi ppc4xx_hsta_msi;

static int hsta_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
{
        struct msi_msg msg;
        struct msi_desc *entry;
        int irq, hwirq;
        u64 addr;

        /* We don't support MSI-X */
        if (type == PCI_CAP_ID_MSIX) {
                pr_debug("%s: MSI-X not supported.\n", __func__);
                return -EINVAL;
        }

        for_each_pci_msi_entry(entry, dev) {
                irq = msi_bitmap_alloc_hwirqs(&ppc4xx_hsta_msi.bmp, 1);
                if (irq < 0) {
                        pr_debug("%s: Failed to allocate msi interrupt\n",
                                 __func__);
                        return irq;
                }

                hwirq = ppc4xx_hsta_msi.irq_map[irq];
                if (!hwirq) {
                        pr_err("%s: Failed mapping irq %d\n", __func__, irq);
                        return -EINVAL;
                }

                /*
                 * HSTA generates interrupts on writes to 128-bit aligned
                 * addresses.
                 */
                addr = ppc4xx_hsta_msi.address + irq*0x10;
                msg.address_hi = upper_32_bits(addr);
                msg.address_lo = lower_32_bits(addr);

                /* Data is not used by the HSTA. */
                msg.data = 0;

                pr_debug("%s: Setup irq %d (0x%0llx)\n", __func__, hwirq,
                         (((u64) msg.address_hi) << 32) | msg.address_lo);

                if (irq_set_msi_desc(hwirq, entry)) {
                        pr_err(
                        "%s: Invalid hwirq %d specified in device tree\n",
                        __func__, hwirq);
                        msi_bitmap_free_hwirqs(&ppc4xx_hsta_msi.bmp, irq, 1);
                        return -EINVAL;
                }
                pci_write_msi_msg(hwirq, &msg);
        }

        return 0;
}

static int hsta_find_hwirq_offset(int hwirq)
{
        int irq;

        /* Find the offset given the hwirq */
        for (irq = 0; irq < ppc4xx_hsta_msi.irq_count; irq++)
                if (ppc4xx_hsta_msi.irq_map[irq] == hwirq)
                        return irq;

        return -EINVAL;
}

static void hsta_teardown_msi_irqs(struct pci_dev *dev)
{
        struct msi_desc *entry;
        int irq;

        for_each_pci_msi_entry(entry, dev) {
                if (!entry->irq)
                        continue;

                irq = hsta_find_hwirq_offset(entry->irq);

                /* entry->irq should always be in irq_map */
                BUG_ON(irq < 0);
                irq_set_msi_desc(entry->irq, NULL);
                msi_bitmap_free_hwirqs(&ppc4xx_hsta_msi.bmp, irq, 1);
                pr_debug("%s: Teardown IRQ %u (index %u)\n", __func__,
                         entry->irq, irq);
        }
}

static int hsta_msi_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct resource *mem;
        int irq, ret, irq_count;
        struct pci_controller *phb;

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!mem) {
                dev_err(dev, "Unable to get mmio space\n");
                return -EINVAL;
        }

        irq_count = of_irq_count(dev->of_node);
        if (!irq_count) {
                dev_err(dev, "Unable to find IRQ range\n");
                return -EINVAL;
        }

        ppc4xx_hsta_msi.dev = dev;
        ppc4xx_hsta_msi.address = mem->start;
        ppc4xx_hsta_msi.data = ioremap(mem->start, resource_size(mem));
        ppc4xx_hsta_msi.irq_count = irq_count;
        if (!ppc4xx_hsta_msi.data) {
                dev_err(dev, "Unable to map memory\n");
                return -ENOMEM;
        }

        ret = msi_bitmap_alloc(&ppc4xx_hsta_msi.bmp, irq_count, dev->of_node);
        if (ret)
                goto out;

        ppc4xx_hsta_msi.irq_map = kmalloc(sizeof(int) * irq_count, GFP_KERNEL);
        if (!ppc4xx_hsta_msi.irq_map) {
                ret = -ENOMEM;
                goto out1;
        }

        /* Setup a mapping from irq offsets to hardware irq numbers */
        for (irq = 0; irq < irq_count; irq++) {
                ppc4xx_hsta_msi.irq_map[irq] =
                        irq_of_parse_and_map(dev->of_node, irq);
                if (!ppc4xx_hsta_msi.irq_map[irq]) {
                        dev_err(dev, "Unable to map IRQ\n");
                        ret = -EINVAL;
                        goto out2;
                }
        }

        list_for_each_entry(phb, &hose_list, list_node) {
                phb->controller_ops.setup_msi_irqs = hsta_setup_msi_irqs;
                phb->controller_ops.teardown_msi_irqs = hsta_teardown_msi_irqs;
        }
        return 0;

out2:
        kfree(ppc4xx_hsta_msi.irq_map);

out1:
        msi_bitmap_free(&ppc4xx_hsta_msi.bmp);

out:
        iounmap(ppc4xx_hsta_msi.data);
        return ret;
}

static const struct of_device_id hsta_msi_ids[] = {
        {
                .compatible = "ibm,hsta-msi",
        },
        {}
};

static struct platform_driver hsta_msi_driver = {
        .probe = hsta_msi_probe,
        .driver = {
                .name = "hsta-msi",
                .of_match_table = hsta_msi_ids,
        },
};

static int hsta_msi_init(void)
{
        return platform_driver_register(&hsta_msi_driver);
}
subsys_initcall(hsta_msi_init);