drivers/firmware/google/coreboot_table.c

   1 /*
   2  * coreboot_table.c
   3  *
   4  * Module providing coreboot table access.
   5  *
   6  * Copyright 2017 Google Inc.
   7  * Copyright 2017 Samuel Holland <samuel@sholland.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License v2.0 as published by
  11  * the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  */
  18
  19 #include <linux/acpi.h>
  20 #include <linux/device.h>
  21 #include <linux/err.h>
  22 #include <linux/init.h>
  23 #include <linux/io.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/of.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/slab.h>
  29
  30 #include "coreboot_table.h"
  31
  32 #define CB_DEV(d) container_of(d, struct coreboot_device, dev)
  33 #define CB_DRV(d) container_of(d, struct coreboot_driver, drv)
  34
  35 static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
  36 {
  37         struct coreboot_device *device = CB_DEV(dev);
  38         struct coreboot_driver *driver = CB_DRV(drv);
  39
  40         return device->entry.tag == driver->tag;
  41 }
  42
  43 static int coreboot_bus_probe(struct device *dev)
  44 {
  45         int ret = -ENODEV;
  46         struct coreboot_device *device = CB_DEV(dev);
  47         struct coreboot_driver *driver = CB_DRV(dev->driver);
  48
  49         if (driver->probe)
  50                 ret = driver->probe(device);
  51
  52         return ret;
  53 }
  54
  55 static int coreboot_bus_remove(struct device *dev)
  56 {
  57         int ret = 0;
  58         struct coreboot_device *device = CB_DEV(dev);
  59         struct coreboot_driver *driver = CB_DRV(dev->driver);
  60
  61         if (driver->remove)
  62                 ret = driver->remove(device);
  63
  64         return ret;
  65 }
  66
  67 static struct bus_type coreboot_bus_type = {
  68         .name           = "coreboot",
  69         .match          = coreboot_bus_match,
  70         .probe          = coreboot_bus_probe,
  71         .remove         = coreboot_bus_remove,
  72 };
  73
  74 static void coreboot_device_release(struct device *dev)
  75 {
  76         struct coreboot_device *device = CB_DEV(dev);
  77
  78         kfree(device);
  79 }
  80
  81 int coreboot_driver_register(struct coreboot_driver *driver)
  82 {
  83         driver->drv.bus = &coreboot_bus_type;
  84
  85         return driver_register(&driver->drv);
  86 }
  87 EXPORT_SYMBOL(coreboot_driver_register);
  88
  89 void coreboot_driver_unregister(struct coreboot_driver *driver)
  90 {
  91         driver_unregister(&driver->drv);
  92 }
  93 EXPORT_SYMBOL(coreboot_driver_unregister);
  94
  95 static int coreboot_table_populate(struct device *dev, void *ptr)
  96 {
  97         int i, ret;
  98         void *ptr_entry;
  99         struct coreboot_device *device;
 100         struct coreboot_table_entry *entry;
 101         struct coreboot_table_header *header = ptr;
 102
 103         ptr_entry = ptr + header->header_bytes;
 104         for (i = 0; i < header->table_entries; i++) {
 105                 entry = ptr_entry;
 106
 107                 device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
 108                 if (!device)
 109                         return -ENOMEM;
 110
 111                 dev_set_name(&device->dev, "coreboot%d", i);
 112                 device->dev.parent = dev;
 113                 device->dev.bus = &coreboot_bus_type;
 114                 device->dev.release = coreboot_device_release;
 115                 memcpy(&device->entry, ptr_entry, entry->size);
 116
 117                 ret = device_register(&device->dev);
 118                 if (ret) {
 119                         put_device(&device->dev);
 120                         return ret;
 121                 }
 122
 123                 ptr_entry += entry->size;
 124         }
 125
 126         return 0;
 127 }
 128
 129 static int coreboot_table_probe(struct platform_device *pdev)
 130 {
 131         resource_size_t len;
 132         struct coreboot_table_header *header;
 133         struct resource *res;
 134         struct device *dev = &pdev->dev;
 135         void *ptr;
 136         int ret;
 137
 138         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 139         if (!res)
 140                 return -EINVAL;
 141
 142         len = resource_size(res);
 143         if (!res->start || !len)
 144                 return -EINVAL;
 145
 146         /* Check just the header first to make sure things are sane */
 147         header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
 148         if (!header)
 149                 return -ENOMEM;
 150
 151         len = header->header_bytes + header->table_bytes;
 152         ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
 153         memunmap(header);
 154         if (ret) {
 155                 dev_warn(dev, "coreboot table missing or corrupt!\n");
 156                 return -ENODEV;
 157         }
 158
 159         ptr = memremap(res->start, len, MEMREMAP_WB);
 160         if (!ptr)
 161                 return -ENOMEM;
 162
 163         ret = bus_register(&coreboot_bus_type);
 164         if (!ret) {
 165                 ret = coreboot_table_populate(dev, ptr);
 166                 if (ret)
 167                         bus_unregister(&coreboot_bus_type);
 168         }
 169         memunmap(ptr);
 170
 171         return ret;
 172 }
 173
 174 static int coreboot_table_remove(struct platform_device *pdev)
 175 {
 176         bus_unregister(&coreboot_bus_type);
 177         return 0;
 178 }
 179
 180 #ifdef CONFIG_ACPI
 181 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
 182         { "GOOGCB00", 0 },
 183         { "BOOT0000", 0 },
 184         { }
 185 };
 186 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
 187 #endif
 188
 189 #ifdef CONFIG_OF
 190 static const struct of_device_id coreboot_of_match[] = {
 191         { .compatible = "coreboot" },
 192         {}
 193 };
 194 MODULE_DEVICE_TABLE(of, coreboot_of_match);
 195 #endif
 196
 197 static struct platform_driver coreboot_table_driver = {
 198         .probe = coreboot_table_probe,
 199         .remove = coreboot_table_remove,
 200         .driver = {
 201                 .name = "coreboot_table",
 202                 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
 203                 .of_match_table = of_match_ptr(coreboot_of_match),
 204         },
 205 };
 206 module_platform_driver(coreboot_table_driver);
 207 MODULE_AUTHOR("Google, Inc.");
 208 MODULE_LICENSE("GPL");