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