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