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