linux/drivers/firmware/google/coreboot_table.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * coreboot_table.c
   4 *
   5 * Module providing coreboot table access.
   6 *
   7 * Copyright 2017 Google Inc.
   8 * Copyright 2017 Samuel Holland <samuel@sholland.org>
   9 */
  10
  11#include <linux/acpi.h>
  12#include <linux/device.h>
  13#include <linux/err.h>
  14#include <linux/init.h>
  15#include <linux/io.h>
  16#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/of.h>
  19#include <linux/platform_device.h>
  20#include <linux/slab.h>
  21
  22#include "coreboot_table.h"
  23
  24#define CB_DEV(d) container_of(d, struct coreboot_device, dev)
  25#define CB_DRV(d) container_of(d, struct coreboot_driver, drv)
  26
  27static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
  28{
  29        struct coreboot_device *device = CB_DEV(dev);
  30        struct coreboot_driver *driver = CB_DRV(drv);
  31
  32        return device->entry.tag == driver->tag;
  33}
  34
  35static int coreboot_bus_probe(struct device *dev)
  36{
  37        int ret = -ENODEV;
  38        struct coreboot_device *device = CB_DEV(dev);
  39        struct coreboot_driver *driver = CB_DRV(dev->driver);
  40
  41        if (driver->probe)
  42                ret = driver->probe(device);
  43
  44        return ret;
  45}
  46
  47static int coreboot_bus_remove(struct device *dev)
  48{
  49        struct coreboot_device *device = CB_DEV(dev);
  50        struct coreboot_driver *driver = CB_DRV(dev->driver);
  51
  52        if (driver->remove)
  53                driver->remove(device);
  54
  55        return 0;
  56}
  57
  58static struct bus_type coreboot_bus_type = {
  59        .name           = "coreboot",
  60        .match          = coreboot_bus_match,
  61        .probe          = coreboot_bus_probe,
  62        .remove         = coreboot_bus_remove,
  63};
  64
  65static void coreboot_device_release(struct device *dev)
  66{
  67        struct coreboot_device *device = CB_DEV(dev);
  68
  69        kfree(device);
  70}
  71
  72int coreboot_driver_register(struct coreboot_driver *driver)
  73{
  74        driver->drv.bus = &coreboot_bus_type;
  75
  76        return driver_register(&driver->drv);
  77}
  78EXPORT_SYMBOL(coreboot_driver_register);
  79
  80void coreboot_driver_unregister(struct coreboot_driver *driver)
  81{
  82        driver_unregister(&driver->drv);
  83}
  84EXPORT_SYMBOL(coreboot_driver_unregister);
  85
  86static int coreboot_table_populate(struct device *dev, void *ptr)
  87{
  88        int i, ret;
  89        void *ptr_entry;
  90        struct coreboot_device *device;
  91        struct coreboot_table_entry *entry;
  92        struct coreboot_table_header *header = ptr;
  93
  94        ptr_entry = ptr + header->header_bytes;
  95        for (i = 0; i < header->table_entries; i++) {
  96                entry = ptr_entry;
  97
  98                device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
  99                if (!device)
 100                        return -ENOMEM;
 101
 102                dev_set_name(&device->dev, "coreboot%d", i);
 103                device->dev.parent = dev;
 104                device->dev.bus = &coreboot_bus_type;
 105                device->dev.release = coreboot_device_release;
 106                memcpy(&device->entry, ptr_entry, entry->size);
 107
 108                ret = device_register(&device->dev);
 109                if (ret) {
 110                        put_device(&device->dev);
 111                        return ret;
 112                }
 113
 114                ptr_entry += entry->size;
 115        }
 116
 117        return 0;
 118}
 119
 120static int coreboot_table_probe(struct platform_device *pdev)
 121{
 122        resource_size_t len;
 123        struct coreboot_table_header *header;
 124        struct resource *res;
 125        struct device *dev = &pdev->dev;
 126        void *ptr;
 127        int ret;
 128
 129        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 130        if (!res)
 131                return -EINVAL;
 132
 133        len = resource_size(res);
 134        if (!res->start || !len)
 135                return -EINVAL;
 136
 137        /* Check just the header first to make sure things are sane */
 138        header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
 139        if (!header)
 140                return -ENOMEM;
 141
 142        len = header->header_bytes + header->table_bytes;
 143        ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
 144        memunmap(header);
 145        if (ret) {
 146                dev_warn(dev, "coreboot table missing or corrupt!\n");
 147                return -ENODEV;
 148        }
 149
 150        ptr = memremap(res->start, len, MEMREMAP_WB);
 151        if (!ptr)
 152                return -ENOMEM;
 153
 154        ret = bus_register(&coreboot_bus_type);
 155        if (!ret) {
 156                ret = coreboot_table_populate(dev, ptr);
 157                if (ret)
 158                        bus_unregister(&coreboot_bus_type);
 159        }
 160        memunmap(ptr);
 161
 162        return ret;
 163}
 164
 165static int __cb_dev_unregister(struct device *dev, void *dummy)
 166{
 167        device_unregister(dev);
 168        return 0;
 169}
 170
 171static int coreboot_table_remove(struct platform_device *pdev)
 172{
 173        bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
 174        bus_unregister(&coreboot_bus_type);
 175        return 0;
 176}
 177
 178#ifdef CONFIG_ACPI
 179static const struct acpi_device_id cros_coreboot_acpi_match[] = {
 180        { "GOOGCB00", 0 },
 181        { "BOOT0000", 0 },
 182        { }
 183};
 184MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
 185#endif
 186
 187#ifdef CONFIG_OF
 188static const struct of_device_id coreboot_of_match[] = {
 189        { .compatible = "coreboot" },
 190        {}
 191};
 192MODULE_DEVICE_TABLE(of, coreboot_of_match);
 193#endif
 194
 195static struct platform_driver coreboot_table_driver = {
 196        .probe = coreboot_table_probe,
 197        .remove = coreboot_table_remove,
 198        .driver = {
 199                .name = "coreboot_table",
 200                .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
 201                .of_match_table = of_match_ptr(coreboot_of_match),
 202        },
 203};
 204module_platform_driver(coreboot_table_driver);
 205MODULE_AUTHOR("Google, Inc.");
 206MODULE_LICENSE("GPL");
 207