coreboot_table.c (4740B)
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 27static 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 35static 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 47static 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 56static 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 63static void coreboot_device_release(struct device *dev) 64{ 65 struct coreboot_device *device = CB_DEV(dev); 66 67 kfree(device); 68} 69 70int coreboot_driver_register(struct coreboot_driver *driver) 71{ 72 driver->drv.bus = &coreboot_bus_type; 73 74 return driver_register(&driver->drv); 75} 76EXPORT_SYMBOL(coreboot_driver_register); 77 78void coreboot_driver_unregister(struct coreboot_driver *driver) 79{ 80 driver_unregister(&driver->drv); 81} 82EXPORT_SYMBOL(coreboot_driver_unregister); 83 84static 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 device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL); 97 if (!device) 98 return -ENOMEM; 99 100 dev_set_name(&device->dev, "coreboot%d", i); 101 device->dev.parent = dev; 102 device->dev.bus = &coreboot_bus_type; 103 device->dev.release = coreboot_device_release; 104 memcpy(&device->entry, ptr_entry, entry->size); 105 106 ret = device_register(&device->dev); 107 if (ret) { 108 put_device(&device->dev); 109 return ret; 110 } 111 112 ptr_entry += entry->size; 113 } 114 115 return 0; 116} 117 118static int coreboot_table_probe(struct platform_device *pdev) 119{ 120 resource_size_t len; 121 struct coreboot_table_header *header; 122 struct resource *res; 123 struct device *dev = &pdev->dev; 124 void *ptr; 125 int ret; 126 127 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 128 if (!res) 129 return -EINVAL; 130 131 len = resource_size(res); 132 if (!res->start || !len) 133 return -EINVAL; 134 135 /* Check just the header first to make sure things are sane */ 136 header = memremap(res->start, sizeof(*header), MEMREMAP_WB); 137 if (!header) 138 return -ENOMEM; 139 140 len = header->header_bytes + header->table_bytes; 141 ret = strncmp(header->signature, "LBIO", sizeof(header->signature)); 142 memunmap(header); 143 if (ret) { 144 dev_warn(dev, "coreboot table missing or corrupt!\n"); 145 return -ENODEV; 146 } 147 148 ptr = memremap(res->start, len, MEMREMAP_WB); 149 if (!ptr) 150 return -ENOMEM; 151 152 ret = bus_register(&coreboot_bus_type); 153 if (!ret) { 154 ret = coreboot_table_populate(dev, ptr); 155 if (ret) 156 bus_unregister(&coreboot_bus_type); 157 } 158 memunmap(ptr); 159 160 return ret; 161} 162 163static int __cb_dev_unregister(struct device *dev, void *dummy) 164{ 165 device_unregister(dev); 166 return 0; 167} 168 169static int coreboot_table_remove(struct platform_device *pdev) 170{ 171 bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister); 172 bus_unregister(&coreboot_bus_type); 173 return 0; 174} 175 176#ifdef CONFIG_ACPI 177static const struct acpi_device_id cros_coreboot_acpi_match[] = { 178 { "GOOGCB00", 0 }, 179 { "BOOT0000", 0 }, 180 { } 181}; 182MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match); 183#endif 184 185#ifdef CONFIG_OF 186static const struct of_device_id coreboot_of_match[] = { 187 { .compatible = "coreboot" }, 188 {} 189}; 190MODULE_DEVICE_TABLE(of, coreboot_of_match); 191#endif 192 193static struct platform_driver coreboot_table_driver = { 194 .probe = coreboot_table_probe, 195 .remove = coreboot_table_remove, 196 .driver = { 197 .name = "coreboot_table", 198 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match), 199 .of_match_table = of_match_ptr(coreboot_of_match), 200 }, 201}; 202module_platform_driver(coreboot_table_driver); 203MODULE_AUTHOR("Google, Inc."); 204MODULE_LICENSE("GPL");