1 /* 2 * coreboot_table.c 3 * 4 * Module providing coreboot table access. 5 * 6 * Copyright 2017 Google Inc. 7 * Copyright 2017 Samuel Holland <samuel@sholland.org> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License v2.0 as published by 11 * the Free Software Foundation. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 */ 18 19 #include <linux/acpi.h> 20 #include <linux/device.h> 21 #include <linux/err.h> 22 #include <linux/init.h> 23 #include <linux/io.h> 24 #include <linux/kernel.h> 25 #include <linux/module.h> 26 #include <linux/of.h> 27 #include <linux/platform_device.h> 28 #include <linux/slab.h> 29 30 #include "coreboot_table.h" 31 32 #define CB_DEV(d) container_of(d, struct coreboot_device, dev) 33 #define CB_DRV(d) container_of(d, struct coreboot_driver, drv) 34 35 static int coreboot_bus_match(struct device *dev, struct device_driver *drv) 36 { 37 struct coreboot_device *device = CB_DEV(dev); 38 struct coreboot_driver *driver = CB_DRV(drv); 39 40 return device->entry.tag == driver->tag; 41 } 42 43 static int coreboot_bus_probe(struct device *dev) 44 { 45 int ret = -ENODEV; 46 struct coreboot_device *device = CB_DEV(dev); 47 struct coreboot_driver *driver = CB_DRV(dev->driver); 48 49 if (driver->probe) 50 ret = driver->probe(device); 51 52 return ret; 53 } 54 55 static int coreboot_bus_remove(struct device *dev) 56 { 57 int ret = 0; 58 struct coreboot_device *device = CB_DEV(dev); 59 struct coreboot_driver *driver = CB_DRV(dev->driver); 60 61 if (driver->remove) 62 ret = driver->remove(device); 63 64 return ret; 65 } 66 67 static struct bus_type coreboot_bus_type = { 68 .name = "coreboot", 69 .match = coreboot_bus_match, 70 .probe = coreboot_bus_probe, 71 .remove = coreboot_bus_remove, 72 }; 73 74 static void coreboot_device_release(struct device *dev) 75 { 76 struct coreboot_device *device = CB_DEV(dev); 77 78 kfree(device); 79 } 80 81 int coreboot_driver_register(struct coreboot_driver *driver) 82 { 83 driver->drv.bus = &coreboot_bus_type; 84 85 return driver_register(&driver->drv); 86 } 87 EXPORT_SYMBOL(coreboot_driver_register); 88 89 void coreboot_driver_unregister(struct coreboot_driver *driver) 90 { 91 driver_unregister(&driver->drv); 92 } 93 EXPORT_SYMBOL(coreboot_driver_unregister); 94 95 static int coreboot_table_populate(struct device *dev, void *ptr) 96 { 97 int i, ret; 98 void *ptr_entry; 99 struct coreboot_device *device; 100 struct coreboot_table_entry *entry; 101 struct coreboot_table_header *header = ptr; 102 103 ptr_entry = ptr + header->header_bytes; 104 for (i = 0; i < header->table_entries; i++) { 105 entry = ptr_entry; 106 107 device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL); 108 if (!device) 109 return -ENOMEM; 110 111 dev_set_name(&device->dev, "coreboot%d", i); 112 device->dev.parent = dev; 113 device->dev.bus = &coreboot_bus_type; 114 device->dev.release = coreboot_device_release; 115 memcpy(&device->entry, ptr_entry, entry->size); 116 117 ret = device_register(&device->dev); 118 if (ret) { 119 put_device(&device->dev); 120 return ret; 121 } 122 123 ptr_entry += entry->size; 124 } 125 126 return 0; 127 } 128 129 static int coreboot_table_probe(struct platform_device *pdev) 130 { 131 resource_size_t len; 132 struct coreboot_table_header *header; 133 struct resource *res; 134 struct device *dev = &pdev->dev; 135 void *ptr; 136 int ret; 137 138 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 139 if (!res) 140 return -EINVAL; 141 142 len = resource_size(res); 143 if (!res->start || !len) 144 return -EINVAL; 145 146 /* Check just the header first to make sure things are sane */ 147 header = memremap(res->start, sizeof(*header), MEMREMAP_WB); 148 if (!header) 149 return -ENOMEM; 150 151 len = header->header_bytes + header->table_bytes; 152 ret = strncmp(header->signature, "LBIO", sizeof(header->signature)); 153 memunmap(header); 154 if (ret) { 155 dev_warn(dev, "coreboot table missing or corrupt!\n"); 156 return -ENODEV; 157 } 158 159 ptr = memremap(res->start, len, MEMREMAP_WB); 160 if (!ptr) 161 return -ENOMEM; 162 163 ret = bus_register(&coreboot_bus_type); 164 if (!ret) { 165 ret = coreboot_table_populate(dev, ptr); 166 if (ret) 167 bus_unregister(&coreboot_bus_type); 168 } 169 memunmap(ptr); 170 171 return ret; 172 } 173 174 static int coreboot_table_remove(struct platform_device *pdev) 175 { 176 bus_unregister(&coreboot_bus_type); 177 return 0; 178 } 179 180 #ifdef CONFIG_ACPI 181 static const struct acpi_device_id cros_coreboot_acpi_match[] = { 182 { "GOOGCB00", 0 }, 183 { "BOOT0000", 0 }, 184 { } 185 }; 186 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match); 187 #endif 188 189 #ifdef CONFIG_OF 190 static const struct of_device_id coreboot_of_match[] = { 191 { .compatible = "coreboot" }, 192 {} 193 }; 194 MODULE_DEVICE_TABLE(of, coreboot_of_match); 195 #endif 196 197 static struct platform_driver coreboot_table_driver = { 198 .probe = coreboot_table_probe, 199 .remove = coreboot_table_remove, 200 .driver = { 201 .name = "coreboot_table", 202 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match), 203 .of_match_table = of_match_ptr(coreboot_of_match), 204 }, 205 }; 206 module_platform_driver(coreboot_table_driver); 207 MODULE_AUTHOR("Google, Inc."); 208 MODULE_LICENSE("GPL"); 209