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
dell_wmi_get_descriptor_valid(void)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
dell_wmi_get_interface_version(u32 * version)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
dell_wmi_get_size(u32 * size)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
dell_wmi_get_hotfix(u32 * hotfix)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 */
dell_wmi_descriptor_probe(struct wmi_device * wdev)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
dell_wmi_descriptor_remove(struct wmi_device * wdev)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");
214
