1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * WMI methods for use with dell-smbios
4 *
5 * Copyright (c) 2017 Dell Inc.
6 */
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/dmi.h>
10 #include <linux/list.h>
11 #include <linux/module.h>
12 #include <linux/mutex.h>
13 #include <linux/uaccess.h>
14 #include <linux/wmi.h>
15 #include "dell-smbios.h"
16 #include "dell-wmi-descriptor.h"
17
18 static DEFINE_MUTEX(call_mutex);
19 static DEFINE_MUTEX(list_mutex);
20 static int wmi_supported;
21
22 struct misc_bios_flags_structure {
23 struct dmi_header header;
24 u16 flags0;
25 } __packed;
26 #define FLAG_HAS_ACPI_WMI 0x02
27
28 #define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
29
30 struct wmi_smbios_priv {
31 struct dell_wmi_smbios_buffer *buf;
32 struct list_head list;
33 struct wmi_device *wdev;
34 struct device *child;
35 u32 req_buf_size;
36 };
37 static LIST_HEAD(wmi_list);
38
get_first_smbios_priv(void)39 static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
40 {
41 return list_first_entry_or_null(&wmi_list,
42 struct wmi_smbios_priv,
43 list);
44 }
45
run_smbios_call(struct wmi_device * wdev)46 static int run_smbios_call(struct wmi_device *wdev)
47 {
48 struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
49 struct wmi_smbios_priv *priv;
50 struct acpi_buffer input;
51 union acpi_object *obj;
52 acpi_status status;
53
54 priv = dev_get_drvdata(&wdev->dev);
55 input.length = priv->req_buf_size - sizeof(u64);
56 input.pointer = &priv->buf->std;
57
58 dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
59 priv->buf->std.cmd_class, priv->buf->std.cmd_select,
60 priv->buf->std.input[0], priv->buf->std.input[1],
61 priv->buf->std.input[2], priv->buf->std.input[3]);
62
63 status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
64 if (ACPI_FAILURE(status))
65 return -EIO;
66 obj = (union acpi_object *)output.pointer;
67 if (obj->type != ACPI_TYPE_BUFFER) {
68 dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
69 if (obj->type == ACPI_TYPE_INTEGER)
70 dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
71 obj->integer.value);
72 kfree(output.pointer);
73 return -EIO;
74 }
75 memcpy(input.pointer, obj->buffer.pointer, obj->buffer.length);
76 dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
77 priv->buf->std.output[0], priv->buf->std.output[1],
78 priv->buf->std.output[2], priv->buf->std.output[3]);
79 kfree(output.pointer);
80
81 return 0;
82 }
83
dell_smbios_wmi_call(struct calling_interface_buffer * buffer)84 static int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
85 {
86 struct wmi_smbios_priv *priv;
87 size_t difference;
88 size_t size;
89 int ret;
90
91 mutex_lock(&call_mutex);
92 priv = get_first_smbios_priv();
93 if (!priv) {
94 ret = -ENODEV;
95 goto out_wmi_call;
96 }
97
98 size = sizeof(struct calling_interface_buffer);
99 difference = priv->req_buf_size - sizeof(u64) - size;
100
101 memset(&priv->buf->ext, 0, difference);
102 memcpy(&priv->buf->std, buffer, size);
103 ret = run_smbios_call(priv->wdev);
104 memcpy(buffer, &priv->buf->std, size);
105 out_wmi_call:
106 mutex_unlock(&call_mutex);
107
108 return ret;
109 }
110
dell_smbios_wmi_filter(struct wmi_device * wdev,unsigned int cmd,struct wmi_ioctl_buffer * arg)111 static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
112 struct wmi_ioctl_buffer *arg)
113 {
114 struct wmi_smbios_priv *priv;
115 int ret = 0;
116
117 switch (cmd) {
118 case DELL_WMI_SMBIOS_CMD:
119 mutex_lock(&call_mutex);
120 priv = dev_get_drvdata(&wdev->dev);
121 if (!priv) {
122 ret = -ENODEV;
123 goto fail_smbios_cmd;
124 }
125 memcpy(priv->buf, arg, priv->req_buf_size);
126 if (dell_smbios_call_filter(&wdev->dev, &priv->buf->std)) {
127 dev_err(&wdev->dev, "Invalid call %d/%d:%8x\n",
128 priv->buf->std.cmd_class,
129 priv->buf->std.cmd_select,
130 priv->buf->std.input[0]);
131 ret = -EFAULT;
132 goto fail_smbios_cmd;
133 }
134 ret = run_smbios_call(priv->wdev);
135 if (ret)
136 goto fail_smbios_cmd;
137 memcpy(arg, priv->buf, priv->req_buf_size);
138 fail_smbios_cmd:
139 mutex_unlock(&call_mutex);
140 break;
141 default:
142 ret = -ENOIOCTLCMD;
143 }
144 return ret;
145 }
146
dell_smbios_wmi_probe(struct wmi_device * wdev,const void * context)147 static int dell_smbios_wmi_probe(struct wmi_device *wdev, const void *context)
148 {
149 struct wmi_driver *wdriver =
150 container_of(wdev->dev.driver, struct wmi_driver, driver);
151 struct wmi_smbios_priv *priv;
152 u32 hotfix;
153 int count;
154 int ret;
155
156 ret = dell_wmi_get_descriptor_valid();
157 if (ret)
158 return ret;
159
160 priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
161 GFP_KERNEL);
162 if (!priv)
163 return -ENOMEM;
164
165 /* WMI buffer size will be either 4k or 32k depending on machine */
166 if (!dell_wmi_get_size(&priv->req_buf_size))
167 return -EPROBE_DEFER;
168
169 /* some SMBIOS calls fail unless BIOS contains hotfix */
170 if (!dell_wmi_get_hotfix(&hotfix))
171 return -EPROBE_DEFER;
172 if (!hotfix) {
173 dev_warn(&wdev->dev,
174 "WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
175 hotfix);
176 wdriver->filter_callback = NULL;
177 }
178
179 /* add in the length object we will use internally with ioctl */
180 priv->req_buf_size += sizeof(u64);
181 ret = set_required_buffer_size(wdev, priv->req_buf_size);
182 if (ret)
183 return ret;
184
185 count = get_order(priv->req_buf_size);
186 priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);
187 if (!priv->buf)
188 return -ENOMEM;
189
190 /* ID is used by dell-smbios to set priority of drivers */
191 wdev->dev.id = 1;
192 ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
193 if (ret)
194 goto fail_register;
195
196 priv->wdev = wdev;
197 dev_set_drvdata(&wdev->dev, priv);
198 mutex_lock(&list_mutex);
199 list_add_tail(&priv->list, &wmi_list);
200 mutex_unlock(&list_mutex);
201
202 return 0;
203
204 fail_register:
205 free_pages((unsigned long)priv->buf, count);
206 return ret;
207 }
208
dell_smbios_wmi_remove(struct wmi_device * wdev)209 static void dell_smbios_wmi_remove(struct wmi_device *wdev)
210 {
211 struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
212 int count;
213
214 mutex_lock(&call_mutex);
215 mutex_lock(&list_mutex);
216 list_del(&priv->list);
217 mutex_unlock(&list_mutex);
218 dell_smbios_unregister_device(&wdev->dev);
219 count = get_order(priv->req_buf_size);
220 free_pages((unsigned long)priv->buf, count);
221 mutex_unlock(&call_mutex);
222 }
223
224 static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
225 { .guid_string = DELL_WMI_SMBIOS_GUID },
226 { },
227 };
228
parse_b1_table(const struct dmi_header * dm)229 static void parse_b1_table(const struct dmi_header *dm)
230 {
231 struct misc_bios_flags_structure *flags =
232 container_of(dm, struct misc_bios_flags_structure, header);
233
234 /* 4 bytes header, 8 bytes flags */
235 if (dm->length < 12)
236 return;
237 if (dm->handle != 0xb100)
238 return;
239 if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
240 wmi_supported = 1;
241 }
242
find_b1(const struct dmi_header * dm,void * dummy)243 static void find_b1(const struct dmi_header *dm, void *dummy)
244 {
245 switch (dm->type) {
246 case 0xb1: /* misc bios flags */
247 parse_b1_table(dm);
248 break;
249 }
250 }
251
252 static struct wmi_driver dell_smbios_wmi_driver = {
253 .driver = {
254 .name = "dell-smbios",
255 },
256 .probe = dell_smbios_wmi_probe,
257 .remove = dell_smbios_wmi_remove,
258 .id_table = dell_smbios_wmi_id_table,
259 .filter_callback = dell_smbios_wmi_filter,
260 };
261
init_dell_smbios_wmi(void)262 int init_dell_smbios_wmi(void)
263 {
264 dmi_walk(find_b1, NULL);
265
266 if (!wmi_supported)
267 return -ENODEV;
268
269 return wmi_driver_register(&dell_smbios_wmi_driver);
270 }
271
exit_dell_smbios_wmi(void)272 void exit_dell_smbios_wmi(void)
273 {
274 if (wmi_supported)
275 wmi_driver_unregister(&dell_smbios_wmi_driver);
276 }
277
278 MODULE_DEVICE_TABLE(wmi, dell_smbios_wmi_id_table);
279