drivers/firmware/google/coreboot_table.c

   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_const(d, struct coreboot_driver, drv)
  26
  27 static int coreboot_bus_match(struct device *dev, const struct device_driver *drv)
  28 {
  29         struct coreboot_device *device = CB_DEV(dev);
  30         const struct coreboot_driver *driver = CB_DRV(drv);
  31         const struct coreboot_device_id *id;
  32
  33         if (!driver->id_table)
  34                 return 0;
  35
  36         for (id = driver->id_table; id->tag; id++) {
  37                 if (device->entry.tag == id->tag)
  38                         return 1;
  39         }
  40
  41         return 0;
  42 }
  43
  44 static int coreboot_bus_probe(struct device *dev)
  45 {
  46         int ret = -ENODEV;
  47         struct coreboot_device *device = CB_DEV(dev);
  48         struct coreboot_driver *driver = CB_DRV(dev->driver);
  49
  50         if (driver->probe)
  51                 ret = driver->probe(device);
  52
  53         return ret;
  54 }
  55
  56 static void coreboot_bus_remove(struct device *dev)
  57 {
  58         struct coreboot_device *device = CB_DEV(dev);
  59         struct coreboot_driver *driver = CB_DRV(dev->driver);
  60
  61         if (driver->remove)
  62                 driver->remove(device);
  63 }
  64
  65 static int coreboot_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
  66 {
  67         struct coreboot_device *device = CB_DEV(dev);
  68         u32 tag = device->entry.tag;
  69
  70         return add_uevent_var(env, "MODALIAS=coreboot:t%08X", tag);
  71 }
  72
  73 static const struct bus_type coreboot_bus_type = {
  74         .name           = "coreboot",
  75         .match          = coreboot_bus_match,
  76         .probe          = coreboot_bus_probe,
  77         .remove         = coreboot_bus_remove,
  78         .uevent         = coreboot_bus_uevent,
  79 };
  80
  81 static void coreboot_device_release(struct device *dev)
  82 {
  83         struct coreboot_device *device = CB_DEV(dev);
  84
  85         kfree(device);
  86 }
  87
  88 int __coreboot_driver_register(struct coreboot_driver *driver,
  89                                struct module *owner)
  90 {
  91         driver->drv.bus = &coreboot_bus_type;
  92         driver->drv.owner = owner;
  93
  94         return driver_register(&driver->drv);
  95 }
  96 EXPORT_SYMBOL(__coreboot_driver_register);
  97
  98 void coreboot_driver_unregister(struct coreboot_driver *driver)
  99 {
 100         driver_unregister(&driver->drv);
 101 }
 102 EXPORT_SYMBOL(coreboot_driver_unregister);
 103
 104 static int coreboot_table_populate(struct device *dev, void *ptr)
 105 {
 106         int i, ret;
 107         void *ptr_entry;
 108         struct coreboot_device *device;
 109         struct coreboot_table_entry *entry;
 110         struct coreboot_table_header *header = ptr;
 111
 112         ptr_entry = ptr + header->header_bytes;
 113         for (i = 0; i < header->table_entries; i++) {
 114                 entry = ptr_entry;
 115
 116                 if (entry->size < sizeof(*entry)) {
 117                         dev_warn(dev, "coreboot table entry too small!\n");
 118                         return -EINVAL;
 119                 }
 120
 121                 device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
 122                 if (!device)
 123                         return -ENOMEM;
 124
 125                 device->dev.parent = dev;
 126                 device->dev.bus = &coreboot_bus_type;
 127                 device->dev.release = coreboot_device_release;
 128                 memcpy(device->raw, ptr_entry, entry->size);
 129
 130                 switch (device->entry.tag) {
 131                 case LB_TAG_CBMEM_ENTRY:
 132                         dev_set_name(&device->dev, "cbmem-%08x",
 133                                      device->cbmem_entry.id);
 134                         break;
 135                 default:
 136                         dev_set_name(&device->dev, "coreboot%d", i);
 137                         break;
 138                 }
 139
 140                 ret = device_register(&device->dev);
 141                 if (ret) {
 142                         put_device(&device->dev);
 143                         return ret;
 144                 }
 145
 146                 ptr_entry += entry->size;
 147         }
 148
 149         return 0;
 150 }
 151
 152 static int coreboot_table_probe(struct platform_device *pdev)
 153 {
 154         resource_size_t len;
 155         struct coreboot_table_header *header;
 156         struct resource *res;
 157         struct device *dev = &pdev->dev;
 158         void *ptr;
 159         int ret;
 160
 161         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 162         if (!res)
 163                 return -EINVAL;
 164
 165         len = resource_size(res);
 166         if (!res->start || !len)
 167                 return -EINVAL;
 168
 169         /* Check just the header first to make sure things are sane */
 170         header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
 171         if (!header)
 172                 return -ENOMEM;
 173
 174         len = header->header_bytes + header->table_bytes;
 175         ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
 176         memunmap(header);
 177         if (ret) {
 178                 dev_warn(dev, "coreboot table missing or corrupt!\n");
 179                 return -ENODEV;
 180         }
 181
 182         ptr = memremap(res->start, len, MEMREMAP_WB);
 183         if (!ptr)
 184                 return -ENOMEM;
 185
 186         ret = coreboot_table_populate(dev, ptr);
 187
 188         memunmap(ptr);
 189
 190         return ret;
 191 }
 192
 193 static int __cb_dev_unregister(struct device *dev, void *dummy)
 194 {
 195         device_unregister(dev);
 196         return 0;
 197 }
 198
 199 static void coreboot_table_remove(struct platform_device *pdev)
 200 {
 201         bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
 202 }
 203
 204 #ifdef CONFIG_ACPI
 205 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
 206         { "GOOGCB00", 0 },
 207         { "BOOT0000", 0 },
 208         { }
 209 };
 210 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
 211 #endif
 212
 213 #ifdef CONFIG_OF
 214 static const struct of_device_id coreboot_of_match[] = {
 215         { .compatible = "coreboot" },
 216         {}
 217 };
 218 MODULE_DEVICE_TABLE(of, coreboot_of_match);
 219 #endif
 220
 221 static struct platform_driver coreboot_table_driver = {
 222         .probe = coreboot_table_probe,
 223         .remove = coreboot_table_remove,
 224         .driver = {
 225                 .name = "coreboot_table",
 226                 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
 227                 .of_match_table = of_match_ptr(coreboot_of_match),
 228         },
 229 };
 230
 231 static int __init coreboot_table_driver_init(void)
 232 {
 233         int ret;
 234
 235         ret = bus_register(&coreboot_bus_type);
 236         if (ret)
 237                 return ret;
 238
 239         ret = platform_driver_register(&coreboot_table_driver);
 240         if (ret) {
 241                 bus_unregister(&coreboot_bus_type);
 242                 return ret;
 243         }
 244
 245         return 0;
 246 }
 247
 248 static void __exit coreboot_table_driver_exit(void)
 249 {
 250         platform_driver_unregister(&coreboot_table_driver);
 251         bus_unregister(&coreboot_bus_type);
 252 }
 253
 254 module_init(coreboot_table_driver_init);
 255 module_exit(coreboot_table_driver_exit);
 256
 257 MODULE_AUTHOR("Google, Inc.");
 258 MODULE_DESCRIPTION("Module providing coreboot table access");
 259 MODULE_LICENSE("GPL");