/*
 * Copyright (C) 2013-2015 ARM Limited, All Rights Reserved.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/acpi_iort.h>
#include <linux/device.h>
#include <linux/msi.h>
#include <linux/of.h>
#include <linux/of_irq.h>

static struct irq_chip its_pmsi_irq_chip = {
        .name                   = "ITS-pMSI",
};

static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
                                  u32 *dev_id)
{
        int ret, index = 0;

        /* Suck the DeviceID out of the msi-parent property */
        do {
                struct of_phandle_args args;

                ret = of_parse_phandle_with_args(dev->of_node,
                                                 "msi-parent", "#msi-cells",
                                                 index, &args);
                if (args.np == irq_domain_get_of_node(domain)) {
                        if (WARN_ON(args.args_count != 1))
                                return -EINVAL;
                        *dev_id = args.args[0];
                        break;
                }
                index++;
        } while (!ret);

        return ret;
}

int __weak iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
{
        return -1;
}

static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
                            int nvec, msi_alloc_info_t *info)
{
        struct msi_domain_info *msi_info;
        u32 dev_id;
        int ret;

        msi_info = msi_get_domain_info(domain->parent);

        if (dev->of_node)
                ret = of_pmsi_get_dev_id(domain, dev, &dev_id);
        else
                ret = iort_pmsi_get_dev_id(dev, &dev_id);
        if (ret)
                return ret;

        /* ITS specific DeviceID, as the core ITS ignores dev. */
        info->scratchpad[0].ul = dev_id;

        /* Allocate at least 32 MSIs, and always as a power of 2 */
        nvec = max_t(int, 32, roundup_pow_of_two(nvec));
        return msi_info->ops->msi_prepare(domain->parent,
                                          dev, nvec, info);
}

static struct msi_domain_ops its_pmsi_ops = {
        .msi_prepare    = its_pmsi_prepare,
};

static struct msi_domain_info its_pmsi_domain_info = {
        .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS),
        .ops    = &its_pmsi_ops,
        .chip   = &its_pmsi_irq_chip,
};

static const struct of_device_id its_device_id[] = {
        {       .compatible     = "arm,gic-v3-its",     },
        {},
};

static int __init its_pmsi_init_one(struct fwnode_handle *fwnode,
                                const char *name)
{
        struct irq_domain *parent;

        parent = irq_find_matching_fwnode(fwnode, DOMAIN_BUS_NEXUS);
        if (!parent || !msi_get_domain_info(parent)) {
                pr_err("%s: unable to locate ITS domain\n", name);
                return -ENXIO;
        }

        if (!platform_msi_create_irq_domain(fwnode, &its_pmsi_domain_info,
                                            parent)) {
                pr_err("%s: unable to create platform domain\n", name);
                return -ENXIO;
        }

        pr_info("Platform MSI: %s domain created\n", name);
        return 0;
}

#ifdef CONFIG_ACPI
static int __init
its_pmsi_parse_madt(struct acpi_subtable_header *header,
                        const unsigned long end)
{
        struct acpi_madt_generic_translator *its_entry;
        struct fwnode_handle *domain_handle;
        const char *node_name;
        int err = -ENXIO;

        its_entry = (struct acpi_madt_generic_translator *)header;
        node_name = kasprintf(GFP_KERNEL, "ITS@0x%lx",
                              (long)its_entry->base_address);
        domain_handle = iort_find_domain_token(its_entry->translation_id);
        if (!domain_handle) {
                pr_err("%s: Unable to locate ITS domain handle\n", node_name);
                goto out;
        }

        err = its_pmsi_init_one(domain_handle, node_name);

out:
        kfree(node_name);
        return err;
}

static void __init its_pmsi_acpi_init(void)
{
        acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
                              its_pmsi_parse_madt, 0);
}
#else
static inline void its_pmsi_acpi_init(void) { }
#endif

static void __init its_pmsi_of_init(void)
{
        struct device_node *np;

        for (np = of_find_matching_node(NULL, its_device_id); np;
             np = of_find_matching_node(np, its_device_id)) {
                if (!of_device_is_available(np))
                        continue;
                if (!of_property_read_bool(np, "msi-controller"))
                        continue;

                its_pmsi_init_one(of_node_to_fwnode(np), np->full_name);
        }
}

static int __init its_pmsi_init(void)
{
        its_pmsi_of_init();
        its_pmsi_acpi_init();
        return 0;
}
early_initcall(its_pmsi_init);