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/device.h>
10 #include <linux/dmi.h>
11 #include <linux/fs.h>
12 #include <linux/list.h>
13 #include <linux/miscdevice.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/uaccess.h>
17 #include <linux/wmi.h>
18 #include <uapi/linux/wmi.h>
19 #include "dell-smbios.h"
20 #include "dell-wmi-descriptor.h"
21
22 static DEFINE_MUTEX(call_mutex);
23 static DEFINE_MUTEX(list_mutex);
24 static int wmi_supported;
25
26 struct misc_bios_flags_structure {
27 struct dmi_header header;
28 u16 flags0;
29 } __packed;
30 #define FLAG_HAS_ACPI_WMI 0x02
31
32 #define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
33
34 struct wmi_smbios_priv {
35 struct dell_wmi_smbios_buffer *buf;
36 struct list_head list;
37 struct wmi_device *wdev;
38 struct device *child;
39 u64 req_buf_size;
40 struct miscdevice char_dev;
41 };
42 static LIST_HEAD(wmi_list);
43
get_first_smbios_priv(void)44 static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
45 {
46 return list_first_entry_or_null(&wmi_list,
47 struct wmi_smbios_priv,
48 list);
49 }
50
run_smbios_call(struct wmi_device * wdev)51 static int run_smbios_call(struct wmi_device *wdev)
52 {
53 struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
54 struct wmi_smbios_priv *priv;
55 struct acpi_buffer input;
56 union acpi_object *obj;
57 acpi_status status;
58
59 priv = dev_get_drvdata(&wdev->dev);
60 input.length = priv->req_buf_size - sizeof(u64);
61 input.pointer = &priv->buf->std;
62
63 dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
64 priv->buf->std.cmd_class, priv->buf->std.cmd_select,
65 priv->buf->std.input[0], priv->buf->std.input[1],
66 priv->buf->std.input[2], priv->buf->std.input[3]);
67
68 status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
69 if (ACPI_FAILURE(status))
70 return -EIO;
71 obj = (union acpi_object *)output.pointer;
72 if (obj->type != ACPI_TYPE_BUFFER) {
73 dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
74 if (obj->type == ACPI_TYPE_INTEGER)
75 dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
76 obj->integer.value);
77 kfree(output.pointer);
78 return -EIO;
79 }
80 memcpy(input.pointer, obj->buffer.pointer, obj->buffer.length);
81 dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
82 priv->buf->std.output[0], priv->buf->std.output[1],
83 priv->buf->std.output[2], priv->buf->std.output[3]);
84 kfree(output.pointer);
85
86 return 0;
87 }
88
dell_smbios_wmi_call(struct calling_interface_buffer * buffer)89 static int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
90 {
91 struct wmi_smbios_priv *priv;
92 size_t difference;
93 size_t size;
94 int ret;
95
96 mutex_lock(&call_mutex);
97 priv = get_first_smbios_priv();
98 if (!priv) {
99 ret = -ENODEV;
100 goto out_wmi_call;
101 }
102
103 size = sizeof(struct calling_interface_buffer);
104 difference = priv->req_buf_size - sizeof(u64) - size;
105
106 memset(&priv->buf->ext, 0, difference);
107 memcpy(&priv->buf->std, buffer, size);
108 ret = run_smbios_call(priv->wdev);
109 memcpy(buffer, &priv->buf->std, size);
110 out_wmi_call:
111 mutex_unlock(&call_mutex);
112
113 return ret;
114 }
115
dell_smbios_wmi_open(struct inode * inode,struct file * filp)116 static int dell_smbios_wmi_open(struct inode *inode, struct file *filp)
117 {
118 struct wmi_smbios_priv *priv;
119
120 priv = container_of(filp->private_data, struct wmi_smbios_priv, char_dev);
121 filp->private_data = priv;
122
123 return nonseekable_open(inode, filp);
124 }
125
dell_smbios_wmi_read(struct file * filp,char __user * buffer,size_t length,loff_t * offset)126 static ssize_t dell_smbios_wmi_read(struct file *filp, char __user *buffer, size_t length,
127 loff_t *offset)
128 {
129 struct wmi_smbios_priv *priv = filp->private_data;
130
131 return simple_read_from_buffer(buffer, length, offset, &priv->req_buf_size,
132 sizeof(priv->req_buf_size));
133 }
134
dell_smbios_wmi_do_ioctl(struct wmi_smbios_priv * priv,struct dell_wmi_smbios_buffer __user * arg)135 static long dell_smbios_wmi_do_ioctl(struct wmi_smbios_priv *priv,
136 struct dell_wmi_smbios_buffer __user *arg)
137 {
138 long ret;
139
140 if (get_user(priv->buf->length, &arg->length))
141 return -EFAULT;
142
143 if (priv->buf->length < priv->req_buf_size)
144 return -EINVAL;
145
146 /* if it's too big, warn, driver will only use what is needed */
147 if (priv->buf->length > priv->req_buf_size)
148 dev_err(&priv->wdev->dev, "Buffer %llu is bigger than required %llu\n",
149 priv->buf->length, priv->req_buf_size);
150
151 if (copy_from_user(priv->buf, arg, priv->req_buf_size))
152 return -EFAULT;
153
154 if (dell_smbios_call_filter(&priv->wdev->dev, &priv->buf->std)) {
155 dev_err(&priv->wdev->dev, "Invalid call %d/%d:%8x\n",
156 priv->buf->std.cmd_class,
157 priv->buf->std.cmd_select,
158 priv->buf->std.input[0]);
159
160 return -EINVAL;
161 }
162
163 ret = run_smbios_call(priv->wdev);
164 if (ret)
165 return ret;
166
167 if (copy_to_user(arg, priv->buf, priv->req_buf_size))
168 return -EFAULT;
169
170 return 0;
171 }
172
dell_smbios_wmi_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)173 static long dell_smbios_wmi_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
174 {
175 struct dell_wmi_smbios_buffer __user *input = (struct dell_wmi_smbios_buffer __user *)arg;
176 struct wmi_smbios_priv *priv = filp->private_data;
177 long ret;
178
179 if (cmd != DELL_WMI_SMBIOS_CMD)
180 return -ENOIOCTLCMD;
181
182 mutex_lock(&call_mutex);
183 ret = dell_smbios_wmi_do_ioctl(priv, input);
184 mutex_unlock(&call_mutex);
185
186 return ret;
187 }
188
189 static const struct file_operations dell_smbios_wmi_fops = {
190 .owner = THIS_MODULE,
191 .open = dell_smbios_wmi_open,
192 .read = dell_smbios_wmi_read,
193 .unlocked_ioctl = dell_smbios_wmi_ioctl,
194 .compat_ioctl = compat_ptr_ioctl,
195 };
196
dell_smbios_wmi_unregister_chardev(void * data)197 static void dell_smbios_wmi_unregister_chardev(void *data)
198 {
199 struct miscdevice *char_dev = data;
200
201 misc_deregister(char_dev);
202 }
203
dell_smbios_wmi_register_chardev(struct wmi_smbios_priv * priv)204 static int dell_smbios_wmi_register_chardev(struct wmi_smbios_priv *priv)
205 {
206 int ret;
207
208 priv->char_dev.minor = MISC_DYNAMIC_MINOR;
209 priv->char_dev.name = "wmi/dell-smbios";
210 priv->char_dev.fops = &dell_smbios_wmi_fops;
211 priv->char_dev.mode = 0444;
212
213 ret = misc_register(&priv->char_dev);
214 if (ret < 0)
215 return ret;
216
217 return devm_add_action_or_reset(&priv->wdev->dev, dell_smbios_wmi_unregister_chardev,
218 &priv->char_dev);
219 }
220
dell_smbios_wmi_probe(struct wmi_device * wdev,const void * context)221 static int dell_smbios_wmi_probe(struct wmi_device *wdev, const void *context)
222 {
223 struct wmi_smbios_priv *priv;
224 u32 buffer_size, hotfix;
225 int count;
226 int ret;
227
228 ret = dell_wmi_get_descriptor_valid();
229 if (ret)
230 return ret;
231
232 priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
233 GFP_KERNEL);
234 if (!priv)
235 return -ENOMEM;
236
237 priv->wdev = wdev;
238 dev_set_drvdata(&wdev->dev, priv);
239
240 /* WMI buffer size will be either 4k or 32k depending on machine */
241 if (!dell_wmi_get_size(&buffer_size))
242 return -EPROBE_DEFER;
243
244 priv->req_buf_size = buffer_size;
245
246 /* some SMBIOS calls fail unless BIOS contains hotfix */
247 if (!dell_wmi_get_hotfix(&hotfix))
248 return -EPROBE_DEFER;
249
250 if (!hotfix)
251 dev_warn(&wdev->dev,
252 "WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
253 hotfix);
254
255 /* add in the length object we will use internally with ioctl */
256 priv->req_buf_size += sizeof(u64);
257
258 count = get_order(priv->req_buf_size);
259 priv->buf = (void *)devm_get_free_pages(&wdev->dev, GFP_KERNEL, count);
260 if (!priv->buf)
261 return -ENOMEM;
262
263 ret = dell_smbios_wmi_register_chardev(priv);
264 if (ret)
265 return ret;
266
267 /* ID is used by dell-smbios to set priority of drivers */
268 wdev->dev.id = 1;
269 ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
270 if (ret)
271 return ret;
272
273 mutex_lock(&list_mutex);
274 list_add_tail(&priv->list, &wmi_list);
275 mutex_unlock(&list_mutex);
276
277 return 0;
278 }
279
dell_smbios_wmi_remove(struct wmi_device * wdev)280 static void dell_smbios_wmi_remove(struct wmi_device *wdev)
281 {
282 struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
283
284 mutex_lock(&call_mutex);
285 mutex_lock(&list_mutex);
286 list_del(&priv->list);
287 mutex_unlock(&list_mutex);
288 dell_smbios_unregister_device(&wdev->dev);
289 mutex_unlock(&call_mutex);
290 }
291
292 static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
293 { .guid_string = DELL_WMI_SMBIOS_GUID },
294 { },
295 };
296
parse_b1_table(const struct dmi_header * dm)297 static void parse_b1_table(const struct dmi_header *dm)
298 {
299 struct misc_bios_flags_structure *flags =
300 container_of(dm, struct misc_bios_flags_structure, header);
301
302 /* 4 bytes header, 8 bytes flags */
303 if (dm->length < 12)
304 return;
305 if (dm->handle != 0xb100)
306 return;
307 if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
308 wmi_supported = 1;
309 }
310
find_b1(const struct dmi_header * dm,void * dummy)311 static void find_b1(const struct dmi_header *dm, void *dummy)
312 {
313 switch (dm->type) {
314 case 0xb1: /* misc bios flags */
315 parse_b1_table(dm);
316 break;
317 }
318 }
319
320 static struct wmi_driver dell_smbios_wmi_driver = {
321 .driver = {
322 .name = "dell-smbios",
323 },
324 .probe = dell_smbios_wmi_probe,
325 .remove = dell_smbios_wmi_remove,
326 .id_table = dell_smbios_wmi_id_table,
327 };
328
init_dell_smbios_wmi(void)329 int init_dell_smbios_wmi(void)
330 {
331 dmi_walk(find_b1, NULL);
332
333 if (!wmi_supported)
334 return -ENODEV;
335
336 return wmi_driver_register(&dell_smbios_wmi_driver);
337 }
338
exit_dell_smbios_wmi(void)339 void exit_dell_smbios_wmi(void)
340 {
341 if (wmi_supported)
342 wmi_driver_unregister(&dell_smbios_wmi_driver);
343 }
344
345 MODULE_DEVICE_TABLE(wmi, dell_smbios_wmi_id_table);
346