drivers/firmware/google/coreboot_table.c

   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                 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
 118 static 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
 163 static int __cb_dev_unregister(struct device *dev, void *dummy)
 164 {
 165         device_unregister(dev);
 166         return 0;
 167 }
 168
 169 static 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
 177 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
 178         { "GOOGCB00", 0 },
 179         { "BOOT0000", 0 },
 180         { }
 181 };
 182 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
 183 #endif
 184
 185 #ifdef CONFIG_OF
 186 static const struct of_device_id coreboot_of_match[] = {
 187         { .compatible = "coreboot" },
 188         {}
 189 };
 190 MODULE_DEVICE_TABLE(of, coreboot_of_match);
 191 #endif
 192
 193 static 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 };
 202 module_platform_driver(coreboot_table_driver);
 203 MODULE_AUTHOR("Google, Inc.");
 204 MODULE_LICENSE("GPL");