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 <[email protected]>
   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
  27 static 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         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 {
  90         driver->drv.bus = &coreboot_bus_type;
  91
  92         return driver_register(&driver->drv);
  93 }
  94 EXPORT_SYMBOL(coreboot_driver_register);
  95
  96 void coreboot_driver_unregister(struct coreboot_driver *driver)
  97 {
  98         driver_unregister(&driver->drv);
  99 }
 100 EXPORT_SYMBOL(coreboot_driver_unregister);
 101
 102 static int coreboot_table_populate(struct device *dev, void *ptr)
 103 {
 104         int i, ret;
 105         void *ptr_entry;
 106         struct coreboot_device *device;
 107         struct coreboot_table_entry *entry;
 108         struct coreboot_table_header *header = ptr;
 109
 110         ptr_entry = ptr + header->header_bytes;
 111         for (i = 0; i < header->table_entries; i++) {
 112                 entry = ptr_entry;
 113
 114                 if (entry->size < sizeof(*entry)) {
 115                         dev_warn(dev, "coreboot table entry too small!\n");
 116                         return -EINVAL;
 117                 }
 118
 119                 device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
 120                 if (!device)
 121                         return -ENOMEM;
 122
 123                 device->dev.parent = dev;
 124                 device->dev.bus = &coreboot_bus_type;
 125                 device->dev.release = coreboot_device_release;
 126                 memcpy(device->raw, ptr_entry, entry->size);
 127
 128                 switch (device->entry.tag) {
 129                 case LB_TAG_CBMEM_ENTRY:
 130                         dev_set_name(&device->dev, "cbmem-%08x",
 131                                      device->cbmem_entry.id);
 132                         break;
 133                 default:
 134                         dev_set_name(&device->dev, "coreboot%d", i);
 135                         break;
 136                 }
 137
 138                 ret = device_register(&device->dev);
 139                 if (ret) {
 140                         put_device(&device->dev);
 141                         return ret;
 142                 }
 143
 144                 ptr_entry += entry->size;
 145         }
 146
 147         return 0;
 148 }
 149
 150 static int coreboot_table_probe(struct platform_device *pdev)
 151 {
 152         resource_size_t len;
 153         struct coreboot_table_header *header;
 154         struct resource *res;
 155         struct device *dev = &pdev->dev;
 156         void *ptr;
 157         int ret;
 158
 159         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 160         if (!res)
 161                 return -EINVAL;
 162
 163         len = resource_size(res);
 164         if (!res->start || !len)
 165                 return -EINVAL;
 166
 167         /* Check just the header first to make sure things are sane */
 168         header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
 169         if (!header)
 170                 return -ENOMEM;
 171
 172         len = header->header_bytes + header->table_bytes;
 173         ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
 174         memunmap(header);
 175         if (ret) {
 176                 dev_warn(dev, "coreboot table missing or corrupt!\n");
 177                 return -ENODEV;
 178         }
 179
 180         ptr = memremap(res->start, len, MEMREMAP_WB);
 181         if (!ptr)
 182                 return -ENOMEM;
 183
 184         ret = coreboot_table_populate(dev, ptr);
 185
 186         memunmap(ptr);
 187
 188         return ret;
 189 }
 190
 191 static int __cb_dev_unregister(struct device *dev, void *dummy)
 192 {
 193         device_unregister(dev);
 194         return 0;
 195 }
 196
 197 static void coreboot_table_remove(struct platform_device *pdev)
 198 {
 199         bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
 200 }
 201
 202 #ifdef CONFIG_ACPI
 203 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
 204         { "GOOGCB00", 0 },
 205         { "BOOT0000", 0 },
 206         { }
 207 };
 208 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
 209 #endif
 210
 211 #ifdef CONFIG_OF
 212 static const struct of_device_id coreboot_of_match[] = {
 213         { .compatible = "coreboot" },
 214         {}
 215 };
 216 MODULE_DEVICE_TABLE(of, coreboot_of_match);
 217 #endif
 218
 219 static struct platform_driver coreboot_table_driver = {
 220         .probe = coreboot_table_probe,
 221         .remove_new = coreboot_table_remove,
 222         .driver = {
 223                 .name = "coreboot_table",
 224                 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
 225                 .of_match_table = of_match_ptr(coreboot_of_match),
 226         },
 227 };
 228
 229 static int __init coreboot_table_driver_init(void)
 230 {
 231         int ret;
 232
 233         ret = bus_register(&coreboot_bus_type);
 234         if (ret)
 235                 return ret;
 236
 237         ret = platform_driver_register(&coreboot_table_driver);
 238         if (ret) {
 239                 bus_unregister(&coreboot_bus_type);
 240                 return ret;
 241         }
 242
 243         return 0;
 244 }
 245
 246 static void __exit coreboot_table_driver_exit(void)
 247 {
 248         platform_driver_unregister(&coreboot_table_driver);
 249         bus_unregister(&coreboot_bus_type);
 250 }
 251
 252 module_init(coreboot_table_driver_init);
 253 module_exit(coreboot_table_driver_exit);
 254
 255 MODULE_AUTHOR("Google, Inc.");
 256 MODULE_LICENSE("GPL");