1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Dell WMI descriptor driver
4 *
5 * Copyright (C) 2017 Dell Inc. All Rights Reserved.
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/acpi.h>
11 #include <linux/list.h>
12 #include <linux/module.h>
13 #include <linux/wmi.h>
14 #include "dell-wmi-descriptor.h"
15
16 #define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"
17
18 struct descriptor_priv {
19 struct list_head list;
20 u32 interface_version;
21 u32 size;
22 u32 hotfix;
23 };
24 static int descriptor_valid = -EPROBE_DEFER;
25 static LIST_HEAD(wmi_list);
26 static DEFINE_MUTEX(list_mutex);
27
dell_wmi_get_descriptor_valid(void)28 int dell_wmi_get_descriptor_valid(void)
29 {
30 if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))
31 return -ENODEV;
32
33 return descriptor_valid;
34 }
35 EXPORT_SYMBOL_GPL(dell_wmi_get_descriptor_valid);
36
dell_wmi_get_interface_version(u32 * version)37 bool dell_wmi_get_interface_version(u32 *version)
38 {
39 struct descriptor_priv *priv;
40 bool ret = false;
41
42 mutex_lock(&list_mutex);
43 priv = list_first_entry_or_null(&wmi_list,
44 struct descriptor_priv,
45 list);
46 if (priv) {
47 *version = priv->interface_version;
48 ret = true;
49 }
50 mutex_unlock(&list_mutex);
51 return ret;
52 }
53 EXPORT_SYMBOL_GPL(dell_wmi_get_interface_version);
54
dell_wmi_get_size(u32 * size)55 bool dell_wmi_get_size(u32 *size)
56 {
57 struct descriptor_priv *priv;
58 bool ret = false;
59
60 mutex_lock(&list_mutex);
61 priv = list_first_entry_or_null(&wmi_list,
62 struct descriptor_priv,
63 list);
64 if (priv) {
65 *size = priv->size;
66 ret = true;
67 }
68 mutex_unlock(&list_mutex);
69 return ret;
70 }
71 EXPORT_SYMBOL_GPL(dell_wmi_get_size);
72
dell_wmi_get_hotfix(u32 * hotfix)73 bool dell_wmi_get_hotfix(u32 *hotfix)
74 {
75 struct descriptor_priv *priv;
76 bool ret = false;
77
78 mutex_lock(&list_mutex);
79 priv = list_first_entry_or_null(&wmi_list,
80 struct descriptor_priv,
81 list);
82 if (priv) {
83 *hotfix = priv->hotfix;
84 ret = true;
85 }
86 mutex_unlock(&list_mutex);
87 return ret;
88 }
89 EXPORT_SYMBOL_GPL(dell_wmi_get_hotfix);
90
91 /*
92 * Descriptor buffer is 128 byte long and contains:
93 *
94 * Name Offset Length Value
95 * Vendor Signature 0 4 "DELL"
96 * Object Signature 4 4 " WMI"
97 * WMI Interface Version 8 4 <version>
98 * WMI buffer length 12 4 <length>
99 * WMI hotfix number 16 4 <hotfix>
100 */
dell_wmi_descriptor_probe(struct wmi_device * wdev,const void * context)101 static int dell_wmi_descriptor_probe(struct wmi_device *wdev,
102 const void *context)
103 {
104 union acpi_object *obj = NULL;
105 struct descriptor_priv *priv;
106 u32 *buffer;
107 int ret;
108
109 obj = wmidev_block_query(wdev, 0);
110 if (!obj) {
111 dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");
112 ret = -EIO;
113 goto out;
114 }
115
116 if (obj->type != ACPI_TYPE_BUFFER) {
117 dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
118 ret = -EINVAL;
119 descriptor_valid = ret;
120 goto out;
121 }
122
123 /* Although it's not technically a failure, this would lead to
124 * unexpected behavior
125 */
126 if (obj->buffer.length != 128) {
127 dev_err(&wdev->dev,
128 "Dell descriptor buffer has unexpected length (%d)\n",
129 obj->buffer.length);
130 ret = -EINVAL;
131 descriptor_valid = ret;
132 goto out;
133 }
134
135 buffer = (u32 *)obj->buffer.pointer;
136
137 if (strncmp(obj->string.pointer, "DELL WMI", 8) != 0) {
138 dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature (%8ph)\n",
139 buffer);
140 ret = -EINVAL;
141 descriptor_valid = ret;
142 goto out;
143 }
144 descriptor_valid = 0;
145
146 if (buffer[2] != 0 && buffer[2] != 1)
147 dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%lu)\n",
148 (unsigned long) buffer[2]);
149
150 priv = devm_kzalloc(&wdev->dev, sizeof(struct descriptor_priv),
151 GFP_KERNEL);
152
153 if (!priv) {
154 ret = -ENOMEM;
155 goto out;
156 }
157
158 priv->interface_version = buffer[2];
159 priv->size = buffer[3];
160 priv->hotfix = buffer[4];
161 ret = 0;
162 dev_set_drvdata(&wdev->dev, priv);
163 mutex_lock(&list_mutex);
164 list_add_tail(&priv->list, &wmi_list);
165 mutex_unlock(&list_mutex);
166
167 dev_dbg(&wdev->dev, "Detected Dell WMI interface version %lu, buffer size %lu, hotfix %lu\n",
168 (unsigned long) priv->interface_version,
169 (unsigned long) priv->size,
170 (unsigned long) priv->hotfix);
171
172 out:
173 kfree(obj);
174 return ret;
175 }
176
dell_wmi_descriptor_remove(struct wmi_device * wdev)177 static void dell_wmi_descriptor_remove(struct wmi_device *wdev)
178 {
179 struct descriptor_priv *priv = dev_get_drvdata(&wdev->dev);
180
181 mutex_lock(&list_mutex);
182 list_del(&priv->list);
183 mutex_unlock(&list_mutex);
184 }
185
186 static const struct wmi_device_id dell_wmi_descriptor_id_table[] = {
187 { .guid_string = DELL_WMI_DESCRIPTOR_GUID },
188 { },
189 };
190
191 static struct wmi_driver dell_wmi_descriptor_driver = {
192 .driver = {
193 .name = "dell-wmi-descriptor",
194 },
195 .probe = dell_wmi_descriptor_probe,
196 .remove = dell_wmi_descriptor_remove,
197 .id_table = dell_wmi_descriptor_id_table,
198 };
199
200 module_wmi_driver(dell_wmi_descriptor_driver);
201
202 MODULE_DEVICE_TABLE(wmi, dell_wmi_descriptor_id_table);
203 MODULE_AUTHOR("Mario Limonciello <mario.limonciello@outlook.com>");
204 MODULE_DESCRIPTION("Dell WMI descriptor driver");
205 MODULE_LICENSE("GPL");
206