drivers/firmware/google/coreboot_table.c

   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/device.h>
  20 #include <linux/err.h>
  21 #include <linux/init.h>
  22 #include <linux/io.h>
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/slab.h>
  26
  27 #include "coreboot_table.h"
  28
  29 #define CB_DEV(d) container_of(d, struct coreboot_device, dev)
  30 #define CB_DRV(d) container_of(d, struct coreboot_driver, drv)
  31
  32 static struct coreboot_table_header __iomem *ptr_header;
  33
  34 static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
  35 {
  36         struct coreboot_device *device = CB_DEV(dev);
  37         struct coreboot_driver *driver = CB_DRV(drv);
  38
  39         return device->entry.tag == driver->tag;
  40 }
  41
  42 static int coreboot_bus_probe(struct device *dev)
  43 {
  44         int ret = -ENODEV;
  45         struct coreboot_device *device = CB_DEV(dev);
  46         struct coreboot_driver *driver = CB_DRV(dev->driver);
  47
  48         if (driver->probe)
  49                 ret = driver->probe(device);
  50
  51         return ret;
  52 }
  53
  54 static int coreboot_bus_remove(struct device *dev)
  55 {
  56         int ret = 0;
  57         struct coreboot_device *device = CB_DEV(dev);
  58         struct coreboot_driver *driver = CB_DRV(dev->driver);
  59
  60         if (driver->remove)
  61                 ret = driver->remove(device);
  62
  63         return ret;
  64 }
  65
  66 static struct bus_type coreboot_bus_type = {
  67         .name           = "coreboot",
  68         .match          = coreboot_bus_match,
  69         .probe          = coreboot_bus_probe,
  70         .remove         = coreboot_bus_remove,
  71 };
  72
  73 static int __init coreboot_bus_init(void)
  74 {
  75         return bus_register(&coreboot_bus_type);
  76 }
  77 module_init(coreboot_bus_init);
  78
  79 static void coreboot_device_release(struct device *dev)
  80 {
  81         struct coreboot_device *device = CB_DEV(dev);
  82
  83         kfree(device);
  84 }
  85
  86 int coreboot_driver_register(struct coreboot_driver *driver)
  87 {
  88         driver->drv.bus = &coreboot_bus_type;
  89
  90         return driver_register(&driver->drv);
  91 }
  92 EXPORT_SYMBOL(coreboot_driver_register);
  93
  94 void coreboot_driver_unregister(struct coreboot_driver *driver)
  95 {
  96         driver_unregister(&driver->drv);
  97 }
  98 EXPORT_SYMBOL(coreboot_driver_unregister);
  99
 100 int coreboot_table_init(struct device *dev, void __iomem *ptr)
 101 {
 102         int i, ret;
 103         void *ptr_entry;
 104         struct coreboot_device *device;
 105         struct coreboot_table_entry entry;
 106         struct coreboot_table_header header;
 107
 108         ptr_header = ptr;
 109         memcpy_fromio(&header, ptr_header, sizeof(header));
 110
 111         if (strncmp(header.signature, "LBIO", sizeof(header.signature))) {
 112                 pr_warn("coreboot_table: coreboot table missing or corrupt!\n");
 113                 ret = -ENODEV;
 114                 goto out;
 115         }
 116
 117         ptr_entry = (void *)ptr_header + header.header_bytes;
 118         for (i = 0; i < header.table_entries; i++) {
 119                 memcpy_fromio(&entry, ptr_entry, sizeof(entry));
 120
 121                 device = kzalloc(sizeof(struct device) + entry.size, GFP_KERNEL);
 122                 if (!device) {
 123                         ret = -ENOMEM;
 124                         break;
 125                 }
 126
 127                 dev_set_name(&device->dev, "coreboot%d", i);
 128                 device->dev.parent = dev;
 129                 device->dev.bus = &coreboot_bus_type;
 130                 device->dev.release = coreboot_device_release;
 131                 memcpy_fromio(&device->entry, ptr_entry, entry.size);
 132
 133                 ret = device_register(&device->dev);
 134                 if (ret) {
 135                         put_device(&device->dev);
 136                         break;
 137                 }
 138
 139                 ptr_entry += entry.size;
 140         }
 141 out:
 142         iounmap(ptr);
 143         return ret;
 144 }
 145 EXPORT_SYMBOL(coreboot_table_init);
 146
 147 int coreboot_table_exit(void)
 148 {
 149         if (ptr_header) {
 150                 bus_unregister(&coreboot_bus_type);
 151                 ptr_header = NULL;
 152         }
 153
 154         return 0;
 155 }
 156 EXPORT_SYMBOL(coreboot_table_exit);
 157
 158 MODULE_AUTHOR("Google, Inc.");
 159 MODULE_LICENSE("GPL");