// SPDX-License-Identifier: GPL-2.0-only
/*
 * coreboot_table.c
 *
 * Module providing coreboot table access.
 *
 * Copyright 2017 Google Inc.
 * Copyright 2017 Samuel Holland <samuel@sholland.org>
 */

#include <linux/acpi.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "coreboot_table.h"

#define CB_DEV(d) container_of(d, struct coreboot_device, dev)
#define CB_DRV(d) container_of(d, struct coreboot_driver, drv)

static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
{
        struct coreboot_device *device = CB_DEV(dev);
        struct coreboot_driver *driver = CB_DRV(drv);

        return device->entry.tag == driver->tag;
}

static int coreboot_bus_probe(struct device *dev)
{
        int ret = -ENODEV;
        struct coreboot_device *device = CB_DEV(dev);
        struct coreboot_driver *driver = CB_DRV(dev->driver);

        if (driver->probe)
                ret = driver->probe(device);

        return ret;
}

static int coreboot_bus_remove(struct device *dev)
{
        int ret = 0;
        struct coreboot_device *device = CB_DEV(dev);
        struct coreboot_driver *driver = CB_DRV(dev->driver);

        if (driver->remove)
                ret = driver->remove(device);

        return ret;
}

static struct bus_type coreboot_bus_type = {
        .name           = "coreboot",
        .match          = coreboot_bus_match,
        .probe          = coreboot_bus_probe,
        .remove         = coreboot_bus_remove,
};

static void coreboot_device_release(struct device *dev)
{
        struct coreboot_device *device = CB_DEV(dev);

        kfree(device);
}

int coreboot_driver_register(struct coreboot_driver *driver)
{
        driver->drv.bus = &coreboot_bus_type;

        return driver_register(&driver->drv);
}
EXPORT_SYMBOL(coreboot_driver_register);

void coreboot_driver_unregister(struct coreboot_driver *driver)
{
        driver_unregister(&driver->drv);
}
EXPORT_SYMBOL(coreboot_driver_unregister);

static int coreboot_table_populate(struct device *dev, void *ptr)
{
        int i, ret;
        void *ptr_entry;
        struct coreboot_device *device;
        struct coreboot_table_entry *entry;
        struct coreboot_table_header *header = ptr;

        ptr_entry = ptr + header->header_bytes;
        for (i = 0; i < header->table_entries; i++) {
                entry = ptr_entry;

                device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
                if (!device)
                        return -ENOMEM;

                dev_set_name(&device->dev, "coreboot%d", i);
                device->dev.parent = dev;
                device->dev.bus = &coreboot_bus_type;
                device->dev.release = coreboot_device_release;
                memcpy(&device->entry, ptr_entry, entry->size);

                ret = device_register(&device->dev);
                if (ret) {
                        put_device(&device->dev);
                        return ret;
                }

                ptr_entry += entry->size;
        }

        return 0;
}

static int coreboot_table_probe(struct platform_device *pdev)
{
        resource_size_t len;
        struct coreboot_table_header *header;
        struct resource *res;
        struct device *dev = &pdev->dev;
        void *ptr;
        int ret;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -EINVAL;

        len = resource_size(res);
        if (!res->start || !len)
                return -EINVAL;

        /* Check just the header first to make sure things are sane */
        header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
        if (!header)
                return -ENOMEM;

        len = header->header_bytes + header->table_bytes;
        ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
        memunmap(header);
        if (ret) {
                dev_warn(dev, "coreboot table missing or corrupt!\n");
                return -ENODEV;
        }

        ptr = memremap(res->start, len, MEMREMAP_WB);
        if (!ptr)
                return -ENOMEM;

        ret = bus_register(&coreboot_bus_type);
        if (!ret) {
                ret = coreboot_table_populate(dev, ptr);
                if (ret)
                        bus_unregister(&coreboot_bus_type);
        }
        memunmap(ptr);

        return ret;
}

static int coreboot_table_remove(struct platform_device *pdev)
{
        bus_unregister(&coreboot_bus_type);
        return 0;
}

#ifdef CONFIG_ACPI
static const struct acpi_device_id cros_coreboot_acpi_match[] = {
        { "GOOGCB00", 0 },
        { "BOOT0000", 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
#endif

#ifdef CONFIG_OF
static const struct of_device_id coreboot_of_match[] = {
        { .compatible = "coreboot" },
        {}
};
MODULE_DEVICE_TABLE(of, coreboot_of_match);
#endif

static struct platform_driver coreboot_table_driver = {
        .probe = coreboot_table_probe,
        .remove = coreboot_table_remove,
        .driver = {
                .name = "coreboot_table",
                .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
                .of_match_table = of_match_ptr(coreboot_of_match),
        },
};
module_platform_driver(coreboot_table_driver);
MODULE_AUTHOR("Google, Inc.");
MODULE_LICENSE("GPL");