drivers/platform/x86/dell-wmi-descriptor.c

   1 /*
   2  * Dell WMI descriptor driver
   3  *
   4  * Copyright (C) 2017 Dell Inc. All Rights Reserved.
   5  *
   6  *  This program is free software; you can redistribute it and/or modify it
   7  *  under the terms of the GNU General Public License version 2 as published
   8  *  by the Free Software Foundation.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/acpi.h>
  19 #include <linux/list.h>
  20 #include <linux/module.h>
  21 #include <linux/wmi.h>
  22 #include "dell-wmi-descriptor.h"
  23
  24 #define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"
  25
  26 struct descriptor_priv {
  27         struct list_head list;
  28         u32 interface_version;
  29         u32 size;
  30         u32 hotfix;
  31 };
  32 static int descriptor_valid = -EPROBE_DEFER;
  33 static LIST_HEAD(wmi_list);
  34 static DEFINE_MUTEX(list_mutex);
  35
  36 int dell_wmi_get_descriptor_valid(void)
  37 {
  38         if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))
  39                 return -ENODEV;
  40
  41         return descriptor_valid;
  42 }
  43 EXPORT_SYMBOL_GPL(dell_wmi_get_descriptor_valid);
  44
  45 bool dell_wmi_get_interface_version(u32 *version)
  46 {
  47         struct descriptor_priv *priv;
  48         bool ret = false;
  49
  50         mutex_lock(&list_mutex);
  51         priv = list_first_entry_or_null(&wmi_list,
  52                                         struct descriptor_priv,
  53                                         list);
  54         if (priv) {
  55                 *version = priv->interface_version;
  56                 ret = true;
  57         }
  58         mutex_unlock(&list_mutex);
  59         return ret;
  60 }
  61 EXPORT_SYMBOL_GPL(dell_wmi_get_interface_version);
  62
  63 bool dell_wmi_get_size(u32 *size)
  64 {
  65         struct descriptor_priv *priv;
  66         bool ret = false;
  67
  68         mutex_lock(&list_mutex);
  69         priv = list_first_entry_or_null(&wmi_list,
  70                                         struct descriptor_priv,
  71                                         list);
  72         if (priv) {
  73                 *size = priv->size;
  74                 ret = true;
  75         }
  76         mutex_unlock(&list_mutex);
  77         return ret;
  78 }
  79 EXPORT_SYMBOL_GPL(dell_wmi_get_size);
  80
  81 bool dell_wmi_get_hotfix(u32 *hotfix)
  82 {
  83         struct descriptor_priv *priv;
  84         bool ret = false;
  85
  86         mutex_lock(&list_mutex);
  87         priv = list_first_entry_or_null(&wmi_list,
  88                                         struct descriptor_priv,
  89                                         list);
  90         if (priv) {
  91                 *hotfix = priv->hotfix;
  92                 ret = true;
  93         }
  94         mutex_unlock(&list_mutex);
  95         return ret;
  96 }
  97 EXPORT_SYMBOL_GPL(dell_wmi_get_hotfix);
  98
  99 /*
 100  * Descriptor buffer is 128 byte long and contains:
 101  *
 102  *       Name             Offset  Length  Value
 103  * Vendor Signature          0       4    "DELL"
 104  * Object Signature          4       4    " WMI"
 105  * WMI Interface Version     8       4    <version>
 106  * WMI buffer length        12       4    <length>
 107  * WMI hotfix number        16       4    <hotfix>
 108  */
 109 static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
 110 {
 111         union acpi_object *obj = NULL;
 112         struct descriptor_priv *priv;
 113         u32 *buffer;
 114         int ret;
 115
 116         obj = wmidev_block_query(wdev, 0);
 117         if (!obj) {
 118                 dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");
 119                 ret = -EIO;
 120                 goto out;
 121         }
 122
 123         if (obj->type != ACPI_TYPE_BUFFER) {
 124                 dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
 125                 ret = -EINVAL;
 126                 descriptor_valid = ret;
 127                 goto out;
 128         }
 129
 130         /* Although it's not technically a failure, this would lead to
 131          * unexpected behavior
 132          */
 133         if (obj->buffer.length != 128) {
 134                 dev_err(&wdev->dev,
 135                         "Dell descriptor buffer has unexpected length (%d)\n",
 136                         obj->buffer.length);
 137                 ret = -EINVAL;
 138                 descriptor_valid = ret;
 139                 goto out;
 140         }
 141
 142         buffer = (u32 *)obj->buffer.pointer;
 143
 144         if (strncmp(obj->string.pointer, "DELL WMI", 8) != 0) {
 145                 dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature (%8ph)\n",
 146                         buffer);
 147                 ret = -EINVAL;
 148                 descriptor_valid = ret;
 149                 goto out;
 150         }
 151         descriptor_valid = 0;
 152
 153         if (buffer[2] != 0 && buffer[2] != 1)
 154                 dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%lu)\n",
 155                         (unsigned long) buffer[2]);
 156
 157         priv = devm_kzalloc(&wdev->dev, sizeof(struct descriptor_priv),
 158         GFP_KERNEL);
 159
 160         if (!priv) {
 161                 ret = -ENOMEM;
 162                 goto out;
 163         }
 164
 165         priv->interface_version = buffer[2];
 166         priv->size = buffer[3];
 167         priv->hotfix = buffer[4];
 168         ret = 0;
 169         dev_set_drvdata(&wdev->dev, priv);
 170         mutex_lock(&list_mutex);
 171         list_add_tail(&priv->list, &wmi_list);
 172         mutex_unlock(&list_mutex);
 173
 174         dev_dbg(&wdev->dev, "Detected Dell WMI interface version %lu, buffer size %lu, hotfix %lu\n",
 175                 (unsigned long) priv->interface_version,
 176                 (unsigned long) priv->size,
 177                 (unsigned long) priv->hotfix);
 178
 179 out:
 180         kfree(obj);
 181         return ret;
 182 }
 183
 184 static int dell_wmi_descriptor_remove(struct wmi_device *wdev)
 185 {
 186         struct descriptor_priv *priv = dev_get_drvdata(&wdev->dev);
 187
 188         mutex_lock(&list_mutex);
 189         list_del(&priv->list);
 190         mutex_unlock(&list_mutex);
 191         return 0;
 192 }
 193
 194 static const struct wmi_device_id dell_wmi_descriptor_id_table[] = {
 195         { .guid_string = DELL_WMI_DESCRIPTOR_GUID },
 196         { },
 197 };
 198
 199 static struct wmi_driver dell_wmi_descriptor_driver = {
 200         .driver = {
 201                 .name = "dell-wmi-descriptor",
 202         },
 203         .probe = dell_wmi_descriptor_probe,
 204         .remove = dell_wmi_descriptor_remove,
 205         .id_table = dell_wmi_descriptor_id_table,
 206 };
 207
 208 module_wmi_driver(dell_wmi_descriptor_driver);
 209
 210 MODULE_ALIAS("wmi:" DELL_WMI_DESCRIPTOR_GUID);
 211 MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
 212 MODULE_DESCRIPTION("Dell WMI descriptor driver");
 213 MODULE_LICENSE("GPL");