1 /*
2 * WMI methods for use with dell-smbios
3 *
4 * Copyright (c) 2017 Dell Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12 #include <linux/dmi.h>
13 #include <linux/list.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/uaccess.h>
17 #include <linux/wmi.h>
18 #include "dell-smbios.h"
19 #include "dell-wmi-descriptor.h"
20
21 static DEFINE_MUTEX(call_mutex);
22 static DEFINE_MUTEX(list_mutex);
23 static int wmi_supported;
24
25 struct misc_bios_flags_structure {
26 struct dmi_header header;
27 u16 flags0;
28 } __packed;
29 #define FLAG_HAS_ACPI_WMI 0x02
30
31 #define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
32
33 struct wmi_smbios_priv {
34 struct dell_wmi_smbios_buffer *buf;
35 struct list_head list;
36 struct wmi_device *wdev;
37 struct device *child;
38 u32 req_buf_size;
39 };
40 static LIST_HEAD(wmi_list);
41
get_first_smbios_priv(void)42 static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
43 {
44 return list_first_entry_or_null(&wmi_list,
45 struct wmi_smbios_priv,
46 list);
47 }
48
run_smbios_call(struct wmi_device * wdev)49 static int run_smbios_call(struct wmi_device *wdev)
50 {
51 struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
52 struct wmi_smbios_priv *priv;
53 struct acpi_buffer input;
54 union acpi_object *obj;
55 acpi_status status;
56
57 priv = dev_get_drvdata(&wdev->dev);
58 input.length = priv->req_buf_size - sizeof(u64);
59 input.pointer = &priv->buf->std;
60
61 dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
62 priv->buf->std.cmd_class, priv->buf->std.cmd_select,
63 priv->buf->std.input[0], priv->buf->std.input[1],
64 priv->buf->std.input[2], priv->buf->std.input[3]);
65
66 status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
67 if (ACPI_FAILURE(status))
68 return -EIO;
69 obj = (union acpi_object *)output.pointer;
70 if (obj->type != ACPI_TYPE_BUFFER) {
71 dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
72 if (obj->type == ACPI_TYPE_INTEGER)
73 dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
74 obj->integer.value);
75 return -EIO;
76 }
77 memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length);
78 dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
79 priv->buf->std.output[0], priv->buf->std.output[1],
80 priv->buf->std.output[2], priv->buf->std.output[3]);
81 kfree(output.pointer);
82
83 return 0;
84 }
85
dell_smbios_wmi_call(struct calling_interface_buffer * buffer)86 static int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
87 {
88 struct wmi_smbios_priv *priv;
89 size_t difference;
90 size_t size;
91 int ret;
92
93 mutex_lock(&call_mutex);
94 priv = get_first_smbios_priv();
95 if (!priv) {
96 ret = -ENODEV;
97 goto out_wmi_call;
98 }
99
100 size = sizeof(struct calling_interface_buffer);
101 difference = priv->req_buf_size - sizeof(u64) - size;
102
103 memset(&priv->buf->ext, 0, difference);
104 memcpy(&priv->buf->std, buffer, size);
105 ret = run_smbios_call(priv->wdev);
106 memcpy(buffer, &priv->buf->std, size);
107 out_wmi_call:
108 mutex_unlock(&call_mutex);
109
110 return ret;
111 }
112
dell_smbios_wmi_filter(struct wmi_device * wdev,unsigned int cmd,struct wmi_ioctl_buffer * arg)113 static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
114 struct wmi_ioctl_buffer *arg)
115 {
116 struct wmi_smbios_priv *priv;
117 int ret = 0;
118
119 switch (cmd) {
120 case DELL_WMI_SMBIOS_CMD:
121 mutex_lock(&call_mutex);
122 priv = dev_get_drvdata(&wdev->dev);
123 if (!priv) {
124 ret = -ENODEV;
125 goto fail_smbios_cmd;
126 }
127 memcpy(priv->buf, arg, priv->req_buf_size);
128 if (dell_smbios_call_filter(&wdev->dev, &priv->buf->std)) {
129 dev_err(&wdev->dev, "Invalid call %d/%d:%8x\n",
130 priv->buf->std.cmd_class,
131 priv->buf->std.cmd_select,
132 priv->buf->std.input[0]);
133 ret = -EFAULT;
134 goto fail_smbios_cmd;
135 }
136 ret = run_smbios_call(priv->wdev);
137 if (ret)
138 goto fail_smbios_cmd;
139 memcpy(arg, priv->buf, priv->req_buf_size);
140 fail_smbios_cmd:
141 mutex_unlock(&call_mutex);
142 break;
143 default:
144 ret = -ENOIOCTLCMD;
145 }
146 return ret;
147 }
148
dell_smbios_wmi_probe(struct wmi_device * wdev)149 static int dell_smbios_wmi_probe(struct wmi_device *wdev)
150 {
151 struct wmi_driver *wdriver =
152 container_of(wdev->dev.driver, struct wmi_driver, driver);
153 struct wmi_smbios_priv *priv;
154 u32 hotfix;
155 int count;
156 int ret;
157
158 ret = dell_wmi_get_descriptor_valid();
159 if (ret)
160 return ret;
161
162 priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
163 GFP_KERNEL);
164 if (!priv)
165 return -ENOMEM;
166
167 /* WMI buffer size will be either 4k or 32k depending on machine */
168 if (!dell_wmi_get_size(&priv->req_buf_size))
169 return -EPROBE_DEFER;
170
171 /* some SMBIOS calls fail unless BIOS contains hotfix */
172 if (!dell_wmi_get_hotfix(&hotfix))
173 return -EPROBE_DEFER;
174 if (!hotfix) {
175 dev_warn(&wdev->dev,
176 "WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
177 hotfix);
178 wdriver->filter_callback = NULL;
179 }
180
181 /* add in the length object we will use internally with ioctl */
182 priv->req_buf_size += sizeof(u64);
183 ret = set_required_buffer_size(wdev, priv->req_buf_size);
184 if (ret)
185 return ret;
186
187 count = get_order(priv->req_buf_size);
188 priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);
189 if (!priv->buf)
190 return -ENOMEM;
191
192 /* ID is used by dell-smbios to set priority of drivers */
193 wdev->dev.id = 1;
194 ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
195 if (ret)
196 goto fail_register;
197
198 priv->wdev = wdev;
199 dev_set_drvdata(&wdev->dev, priv);
200 mutex_lock(&list_mutex);
201 list_add_tail(&priv->list, &wmi_list);
202 mutex_unlock(&list_mutex);
203
204 return 0;
205
206 fail_register:
207 free_pages((unsigned long)priv->buf, count);
208 return ret;
209 }
210
dell_smbios_wmi_remove(struct wmi_device * wdev)211 static int dell_smbios_wmi_remove(struct wmi_device *wdev)
212 {
213 struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
214 int count;
215
216 mutex_lock(&call_mutex);
217 mutex_lock(&list_mutex);
218 list_del(&priv->list);
219 mutex_unlock(&list_mutex);
220 dell_smbios_unregister_device(&wdev->dev);
221 count = get_order(priv->req_buf_size);
222 free_pages((unsigned long)priv->buf, count);
223 mutex_unlock(&call_mutex);
224 return 0;
225 }
226
227 static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
228 { .guid_string = DELL_WMI_SMBIOS_GUID },
229 { },
230 };
231
parse_b1_table(const struct dmi_header * dm)232 static void parse_b1_table(const struct dmi_header *dm)
233 {
234 struct misc_bios_flags_structure *flags =
235 container_of(dm, struct misc_bios_flags_structure, header);
236
237 /* 4 bytes header, 8 bytes flags */
238 if (dm->length < 12)
239 return;
240 if (dm->handle != 0xb100)
241 return;
242 if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
243 wmi_supported = 1;
244 }
245
find_b1(const struct dmi_header * dm,void * dummy)246 static void find_b1(const struct dmi_header *dm, void *dummy)
247 {
248 switch (dm->type) {
249 case 0xb1: /* misc bios flags */
250 parse_b1_table(dm);
251 break;
252 }
253 }
254
255 static struct wmi_driver dell_smbios_wmi_driver = {
256 .driver = {
257 .name = "dell-smbios",
258 },
259 .probe = dell_smbios_wmi_probe,
260 .remove = dell_smbios_wmi_remove,
261 .id_table = dell_smbios_wmi_id_table,
262 .filter_callback = dell_smbios_wmi_filter,
263 };
264
init_dell_smbios_wmi(void)265 int init_dell_smbios_wmi(void)
266 {
267 dmi_walk(find_b1, NULL);
268
269 if (!wmi_supported)
270 return -ENODEV;
271
272 return wmi_driver_register(&dell_smbios_wmi_driver);
273 }
274
exit_dell_smbios_wmi(void)275 void exit_dell_smbios_wmi(void)
276 {
277 wmi_driver_unregister(&dell_smbios_wmi_driver);
278 }
279
280 MODULE_ALIAS("wmi:" DELL_WMI_SMBIOS_GUID);
281
