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/mod_devicetable.h> 18 #include <linux/module.h> 19 #include <linux/of.h> 20 #include <linux/platform_device.h> 21 #include <linux/slab.h> 22 23 #include "coreboot_table.h" 24 25 /* Coreboot table header structure */ 26 struct coreboot_table_header { 27 char signature[4]; 28 u32 header_bytes; 29 u32 header_checksum; 30 u32 table_bytes; 31 u32 table_checksum; 32 u32 table_entries; 33 }; 34 35 #define CB_DEV(d) container_of(d, struct coreboot_device, dev) 36 #define CB_DRV(d) container_of_const(d, struct coreboot_driver, drv) 37 38 static int coreboot_bus_match(struct device *dev, const struct device_driver *drv) 39 { 40 struct coreboot_device *device = CB_DEV(dev); 41 const struct coreboot_driver *driver = CB_DRV(drv); 42 const struct coreboot_device_id *id; 43 44 if (!driver->id_table) 45 return 0; 46 47 for (id = driver->id_table; id->tag; id++) { 48 if (device->entry.tag == id->tag) 49 return 1; 50 } 51 52 return 0; 53 } 54 55 static int coreboot_bus_probe(struct device *dev) 56 { 57 int ret = -ENODEV; 58 struct coreboot_device *device = CB_DEV(dev); 59 struct coreboot_driver *driver = CB_DRV(dev->driver); 60 61 if (driver->probe) 62 ret = driver->probe(device); 63 64 return ret; 65 } 66 67 static void coreboot_bus_remove(struct device *dev) 68 { 69 struct coreboot_device *device = CB_DEV(dev); 70 struct coreboot_driver *driver = CB_DRV(dev->driver); 71 72 if (driver->remove) 73 driver->remove(device); 74 } 75 76 static int coreboot_bus_uevent(const struct device *dev, struct kobj_uevent_env *env) 77 { 78 struct coreboot_device *device = CB_DEV(dev); 79 u32 tag = device->entry.tag; 80 81 return add_uevent_var(env, "MODALIAS=coreboot:t%08X", tag); 82 } 83 84 static const struct bus_type coreboot_bus_type = { 85 .name = "coreboot", 86 .match = coreboot_bus_match, 87 .probe = coreboot_bus_probe, 88 .remove = coreboot_bus_remove, 89 .uevent = coreboot_bus_uevent, 90 }; 91 92 static void coreboot_device_release(struct device *dev) 93 { 94 struct coreboot_device *device = CB_DEV(dev); 95 96 kfree(device); 97 } 98 99 int __coreboot_driver_register(struct coreboot_driver *driver, 100 struct module *owner) 101 { 102 driver->drv.bus = &coreboot_bus_type; 103 driver->drv.owner = owner; 104 105 return driver_register(&driver->drv); 106 } 107 EXPORT_SYMBOL(__coreboot_driver_register); 108 109 void coreboot_driver_unregister(struct coreboot_driver *driver) 110 { 111 driver_unregister(&driver->drv); 112 } 113 EXPORT_SYMBOL(coreboot_driver_unregister); 114 115 static int coreboot_table_populate(struct device *dev, void *ptr, resource_size_t len) 116 { 117 int i, ret; 118 void *ptr_entry; 119 struct coreboot_device *device; 120 struct coreboot_table_entry *entry; 121 struct coreboot_table_header *header = ptr; 122 void *ptr_end; 123 124 ptr_end = ptr + len; 125 ptr_entry = ptr + header->header_bytes; 126 for (i = 0; i < header->table_entries; i++) { 127 if (ptr_entry + sizeof(*entry) > ptr_end) 128 return -EINVAL; 129 entry = ptr_entry; 130 131 if (entry->size < sizeof(*entry)) { 132 dev_warn(dev, "coreboot table entry too small!\n"); 133 return -EINVAL; 134 } 135 136 if (ptr_entry + entry->size > ptr_end) 137 return -EINVAL; 138 139 device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL); 140 if (!device) 141 return -ENOMEM; 142 143 device->dev.parent = dev; 144 device->dev.bus = &coreboot_bus_type; 145 device->dev.release = coreboot_device_release; 146 memcpy(device->raw, ptr_entry, entry->size); 147 148 switch (device->entry.tag) { 149 case LB_TAG_CBMEM_ENTRY: 150 dev_set_name(&device->dev, "cbmem-%08x", 151 device->cbmem_entry.id); 152 break; 153 default: 154 dev_set_name(&device->dev, "coreboot%d", i); 155 break; 156 } 157 158 ptr_entry += entry->size; 159 160 ret = device_register(&device->dev); 161 if (ret) { 162 dev_warn(dev, "failed to register coreboot device: %d\n", ret); 163 put_device(&device->dev); 164 } 165 } 166 167 return 0; 168 } 169 170 static int coreboot_table_probe(struct platform_device *pdev) 171 { 172 resource_size_t len; 173 struct coreboot_table_header *header; 174 struct resource *res; 175 struct device *dev = &pdev->dev; 176 void *ptr; 177 int ret; 178 179 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 180 if (!res) 181 return -EINVAL; 182 183 len = resource_size(res); 184 if (!res->start || !len) 185 return -EINVAL; 186 187 /* Check just the header first to make sure things are sane */ 188 header = memremap(res->start, sizeof(*header), MEMREMAP_WB); 189 if (!header) 190 return -ENOMEM; 191 192 len = header->header_bytes + header->table_bytes; 193 ret = strncmp(header->signature, "LBIO", sizeof(header->signature)); 194 memunmap(header); 195 if (ret) { 196 dev_warn(dev, "coreboot table missing or corrupt!\n"); 197 return -ENODEV; 198 } 199 200 ptr = memremap(res->start, len, MEMREMAP_WB); 201 if (!ptr) 202 return -ENOMEM; 203 204 ret = coreboot_table_populate(dev, ptr, len); 205 206 memunmap(ptr); 207 208 return ret; 209 } 210 211 static int __cb_dev_unregister(struct device *dev, void *dummy) 212 { 213 device_unregister(dev); 214 return 0; 215 } 216 217 static void coreboot_table_remove(struct platform_device *pdev) 218 { 219 bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister); 220 } 221 222 #ifdef CONFIG_ACPI 223 static const struct acpi_device_id cros_coreboot_acpi_match[] = { 224 { "GOOGCB00", 0 }, 225 { "BOOT0000", 0 }, 226 { } 227 }; 228 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match); 229 #endif 230 231 #ifdef CONFIG_OF 232 static const struct of_device_id coreboot_of_match[] = { 233 { .compatible = "coreboot" }, 234 {} 235 }; 236 MODULE_DEVICE_TABLE(of, coreboot_of_match); 237 #endif 238 239 static struct platform_driver coreboot_table_driver = { 240 .probe = coreboot_table_probe, 241 .remove = coreboot_table_remove, 242 .driver = { 243 .name = "coreboot_table", 244 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match), 245 .of_match_table = of_match_ptr(coreboot_of_match), 246 }, 247 }; 248 249 static int __init coreboot_table_driver_init(void) 250 { 251 int ret; 252 253 ret = bus_register(&coreboot_bus_type); 254 if (ret) 255 return ret; 256 257 ret = platform_driver_register(&coreboot_table_driver); 258 if (ret) { 259 bus_unregister(&coreboot_bus_type); 260 return ret; 261 } 262 263 return 0; 264 } 265 266 static void __exit coreboot_table_driver_exit(void) 267 { 268 platform_driver_unregister(&coreboot_table_driver); 269 bus_unregister(&coreboot_bus_type); 270 } 271 272 subsys_initcall(coreboot_table_driver_init); 273 module_exit(coreboot_table_driver_exit); 274 275 MODULE_AUTHOR("Google, Inc."); 276 MODULE_DESCRIPTION("Module providing coreboot table access"); 277 MODULE_LICENSE("GPL"); 278