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) 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; 122 123 ptr_entry = ptr + header->header_bytes; 124 for (i = 0; i < header->table_entries; i++) { 125 entry = ptr_entry; 126 127 if (entry->size < sizeof(*entry)) { 128 dev_warn(dev, "coreboot table entry too small!\n"); 129 return -EINVAL; 130 } 131 132 device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL); 133 if (!device) 134 return -ENOMEM; 135 136 device->dev.parent = dev; 137 device->dev.bus = &coreboot_bus_type; 138 device->dev.release = coreboot_device_release; 139 memcpy(device->raw, ptr_entry, entry->size); 140 141 switch (device->entry.tag) { 142 case LB_TAG_CBMEM_ENTRY: 143 dev_set_name(&device->dev, "cbmem-%08x", 144 device->cbmem_entry.id); 145 break; 146 default: 147 dev_set_name(&device->dev, "coreboot%d", i); 148 break; 149 } 150 151 ret = device_register(&device->dev); 152 if (ret) { 153 put_device(&device->dev); 154 return ret; 155 } 156 157 ptr_entry += entry->size; 158 } 159 160 return 0; 161 } 162 163 static int coreboot_table_probe(struct platform_device *pdev) 164 { 165 resource_size_t len; 166 struct coreboot_table_header *header; 167 struct resource *res; 168 struct device *dev = &pdev->dev; 169 void *ptr; 170 int ret; 171 172 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 173 if (!res) 174 return -EINVAL; 175 176 len = resource_size(res); 177 if (!res->start || !len) 178 return -EINVAL; 179 180 /* Check just the header first to make sure things are sane */ 181 header = memremap(res->start, sizeof(*header), MEMREMAP_WB); 182 if (!header) 183 return -ENOMEM; 184 185 len = header->header_bytes + header->table_bytes; 186 ret = strncmp(header->signature, "LBIO", sizeof(header->signature)); 187 memunmap(header); 188 if (ret) { 189 dev_warn(dev, "coreboot table missing or corrupt!\n"); 190 return -ENODEV; 191 } 192 193 ptr = memremap(res->start, len, MEMREMAP_WB); 194 if (!ptr) 195 return -ENOMEM; 196 197 ret = coreboot_table_populate(dev, ptr); 198 199 memunmap(ptr); 200 201 return ret; 202 } 203 204 static int __cb_dev_unregister(struct device *dev, void *dummy) 205 { 206 device_unregister(dev); 207 return 0; 208 } 209 210 static void coreboot_table_remove(struct platform_device *pdev) 211 { 212 bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister); 213 } 214 215 #ifdef CONFIG_ACPI 216 static const struct acpi_device_id cros_coreboot_acpi_match[] = { 217 { "GOOGCB00", 0 }, 218 { "BOOT0000", 0 }, 219 { } 220 }; 221 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match); 222 #endif 223 224 #ifdef CONFIG_OF 225 static const struct of_device_id coreboot_of_match[] = { 226 { .compatible = "coreboot" }, 227 {} 228 }; 229 MODULE_DEVICE_TABLE(of, coreboot_of_match); 230 #endif 231 232 static struct platform_driver coreboot_table_driver = { 233 .probe = coreboot_table_probe, 234 .remove = coreboot_table_remove, 235 .driver = { 236 .name = "coreboot_table", 237 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match), 238 .of_match_table = of_match_ptr(coreboot_of_match), 239 }, 240 }; 241 242 static int __init coreboot_table_driver_init(void) 243 { 244 int ret; 245 246 ret = bus_register(&coreboot_bus_type); 247 if (ret) 248 return ret; 249 250 ret = platform_driver_register(&coreboot_table_driver); 251 if (ret) { 252 bus_unregister(&coreboot_bus_type); 253 return ret; 254 } 255 256 return 0; 257 } 258 259 static void __exit coreboot_table_driver_exit(void) 260 { 261 platform_driver_unregister(&coreboot_table_driver); 262 bus_unregister(&coreboot_bus_type); 263 } 264 265 subsys_initcall(coreboot_table_driver_init); 266 module_exit(coreboot_table_driver_exit); 267 268 MODULE_AUTHOR("Google, Inc."); 269 MODULE_DESCRIPTION("Module providing coreboot table access"); 270 MODULE_LICENSE("GPL"); 271