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