1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Functions corresponding to methods under BIOS interface GUID
4  * for use with hp-bioscfg driver.
5  *
6  *  Copyright (c) 2022 Hewlett-Packard Inc.
7  */
8 
9 #include <linux/wmi.h>
10 #include "bioscfg.h"
11 
12 /*
13  * struct bios_args buffer is dynamically allocated.  New WMI command types
14  * were introduced that exceeds 128-byte data size.  Changes to handle
15  * the data size allocation scheme were kept in hp_wmi_perform_query function.
16  */
17 struct bios_args {
18 	u32 signature;
19 	u32 command;
20 	u32 commandtype;
21 	u32 datasize;
22 	u8 data[] __counted_by(datasize);
23 };
24 
25 /**
26  * hp_set_attribute
27  *
28  * @a_name: The attribute name
29  * @a_value: The attribute value
30  *
31  * Sets an attribute to new value
32  *
33  * Returns zero on success
34  *	-ENODEV if device is not found
35  *	-EINVAL if the instance of 'Setup Admin' password is not found.
36  *	-ENOMEM unable to allocate memory
37  */
38 int hp_set_attribute(const char *a_name, const char *a_value)
39 {
40 	int security_area_size;
41 	int a_name_size, a_value_size;
42 	u16 *buffer = NULL;
43 	u16 *start;
44 	int  buffer_size, instance, ret;
45 	char *auth_token_choice;
46 
47 	mutex_lock(&bioscfg_drv.mutex);
48 
49 	instance = hp_get_password_instance_for_type(SETUP_PASSWD);
50 	if (instance < 0) {
51 		ret = -EINVAL;
52 		goto out_set_attribute;
53 	}
54 
55 	/* Select which auth token to use; password or [auth token] */
56 	if (bioscfg_drv.spm_data.auth_token)
57 		auth_token_choice = bioscfg_drv.spm_data.auth_token;
58 	else
59 		auth_token_choice = bioscfg_drv.password_data[instance].current_password;
60 
61 	a_name_size = hp_calculate_string_buffer(a_name);
62 	a_value_size = hp_calculate_string_buffer(a_value);
63 	security_area_size = hp_calculate_security_buffer(auth_token_choice);
64 	buffer_size = a_name_size + a_value_size + security_area_size;
65 
66 	buffer = kmalloc(buffer_size + 1, GFP_KERNEL);
67 	if (!buffer) {
68 		ret = -ENOMEM;
69 		goto out_set_attribute;
70 	}
71 
72 	/* build variables to set */
73 	start = buffer;
74 	start = hp_ascii_to_utf16_unicode(start, a_name);
75 	if (!start) {
76 		ret = -EINVAL;
77 		goto out_set_attribute;
78 	}
79 
80 	start = hp_ascii_to_utf16_unicode(start, a_value);
81 	if (!start) {
82 		ret = -EINVAL;
83 		goto out_set_attribute;
84 	}
85 
86 	ret = hp_populate_security_buffer(start, auth_token_choice);
87 	if (ret < 0)
88 		goto out_set_attribute;
89 
90 	ret = hp_wmi_set_bios_setting(buffer, buffer_size);
91 
92 out_set_attribute:
93 	kfree(buffer);
94 	mutex_unlock(&bioscfg_drv.mutex);
95 	return ret;
96 }
97 
98 /**
99  * hp_wmi_perform_query
100  *
101  * @query:	The commandtype (enum hp_wmi_commandtype)
102  * @command:	The command (enum hp_wmi_command)
103  * @buffer:	Buffer used as input and/or output
104  * @insize:	Size of input buffer
105  * @outsize:	Size of output buffer
106  *
107  * returns zero on success
108  *         an HP WMI query specific error code (which is positive)
109  *         -EINVAL if the query was not successful at all
110  *         -EINVAL if the output buffer size exceeds buffersize
111  *
112  * Note: The buffersize must at least be the maximum of the input and output
113  *       size. E.g. Battery info query is defined to have 1 byte input
114  *       and 128 byte output. The caller would do:
115  *       buffer = kzalloc(128, GFP_KERNEL);
116  *       ret = hp_wmi_perform_query(HPWMI_BATTERY_QUERY, HPWMI_READ,
117  *				    buffer, 1, 128)
118  */
119 int hp_wmi_perform_query(int query, enum hp_wmi_command command, void *buffer,
120 			 u32 insize, u32 outsize)
121 {
122 	struct acpi_buffer input, output = { ACPI_ALLOCATE_BUFFER, NULL };
123 	struct bios_return *bios_return;
124 	union acpi_object *obj = NULL;
125 	struct bios_args *args = NULL;
126 	int mid, actual_outsize, ret;
127 	size_t bios_args_size;
128 
129 	mid = hp_encode_outsize_for_pvsz(outsize);
130 	if (WARN_ON(mid < 0))
131 		return mid;
132 
133 	bios_args_size = struct_size(args, data, insize);
134 	args = kmalloc(bios_args_size, GFP_KERNEL);
135 	if (!args)
136 		return -ENOMEM;
137 
138 	input.length = bios_args_size;
139 	input.pointer = args;
140 
141 	/* BIOS expects 'SECU' in hex as the signature value*/
142 	args->signature = 0x55434553;
143 	args->command = command;
144 	args->commandtype = query;
145 	args->datasize = insize;
146 	memcpy(args->data, buffer, flex_array_size(args, data, insize));
147 
148 	ret = wmi_evaluate_method(HP_WMI_BIOS_GUID, 0, mid, &input, &output);
149 	if (ret)
150 		goto out_free;
151 
152 	obj = output.pointer;
153 	if (!obj) {
154 		ret = -EINVAL;
155 		goto out_free;
156 	}
157 
158 	if (obj->type != ACPI_TYPE_BUFFER ||
159 	    obj->buffer.length < sizeof(*bios_return)) {
160 		pr_warn("query 0x%x returned wrong type or too small buffer\n", query);
161 		ret = -EINVAL;
162 		goto out_free;
163 	}
164 
165 	bios_return = (struct bios_return *)obj->buffer.pointer;
166 	ret = bios_return->return_code;
167 	if (ret) {
168 		if (ret != INVALID_CMD_VALUE && ret != INVALID_CMD_TYPE)
169 			pr_warn("query 0x%x returned error 0x%x\n", query, ret);
170 		goto out_free;
171 	}
172 
173 	/* Ignore output data of zero size */
174 	if (!outsize)
175 		goto out_free;
176 
177 	actual_outsize = min_t(u32, outsize, obj->buffer.length - sizeof(*bios_return));
178 	memcpy_and_pad(buffer, outsize, obj->buffer.pointer + sizeof(*bios_return),
179 		       actual_outsize, 0);
180 
181 out_free:
182 	ret = hp_wmi_error_and_message(ret);
183 
184 	kfree(obj);
185 	kfree(args);
186 	return ret;
187 }
188 
189 static void *utf16_empty_string(u16 *p)
190 {
191 	*p++ = 2;
192 	*p++ = 0x00;
193 	return p;
194 }
195 
196 /**
197  * hp_ascii_to_utf16_unicode -  Convert ascii string to UTF-16 unicode
198  *
199  * BIOS supports UTF-16 characters that are 2 bytes long.  No variable
200  * multi-byte language supported.
201  *
202  * @p:   Unicode buffer address
203  * @str: string to convert to unicode
204  *
205  * Returns a void pointer to the buffer string
206  */
207 void *hp_ascii_to_utf16_unicode(u16 *p, const u8 *str)
208 {
209 	int len = strlen(str);
210 	int ret;
211 
212 	/*
213 	 * Add null character when reading an empty string
214 	 * "02 00 00 00"
215 	 */
216 	if (len == 0)
217 		return utf16_empty_string(p);
218 
219 	/* Move pointer len * 2 number of bytes */
220 	*p++ = len * 2;
221 	ret = utf8s_to_utf16s(str, strlen(str), UTF16_HOST_ENDIAN, p, len);
222 	if (ret < 0) {
223 		dev_err(bioscfg_drv.class_dev, "UTF16 conversion failed\n");
224 		return NULL;
225 	}
226 
227 	if (ret * sizeof(u16) > U16_MAX) {
228 		dev_err(bioscfg_drv.class_dev, "Error string too long\n");
229 		return NULL;
230 	}
231 
232 	p += len;
233 	return p;
234 }
235 
236 /**
237  * hp_wmi_set_bios_setting - Set setting's value in BIOS
238  *
239  * @input_buffer: Input buffer address
240  * @input_size:   Input buffer size
241  *
242  * Returns: Count of unicode characters written to BIOS if successful, otherwise
243  *		-ENOMEM unable to allocate memory
244  *		-EINVAL buffer not allocated or too small
245  */
246 int hp_wmi_set_bios_setting(u16 *input_buffer, u32 input_size)
247 {
248 	union acpi_object *obj;
249 	struct acpi_buffer input = {input_size, input_buffer};
250 	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
251 	int ret;
252 
253 	ret = wmi_evaluate_method(HP_WMI_SET_BIOS_SETTING_GUID, 0, 1, &input, &output);
254 
255 	obj = output.pointer;
256 	if (!obj)
257 		return -EINVAL;
258 
259 	if (obj->type != ACPI_TYPE_INTEGER) {
260 		ret = -EINVAL;
261 		goto out_free;
262 	}
263 
264 	ret = obj->integer.value;
265 	if (ret) {
266 		ret = hp_wmi_error_and_message(ret);
267 		goto out_free;
268 	}
269 
270 out_free:
271 	kfree(obj);
272 	return ret;
273 }
274 
275 static int hp_attr_set_interface_probe(struct wmi_device *wdev, const void *context)
276 {
277 	mutex_lock(&bioscfg_drv.mutex);
278 	mutex_unlock(&bioscfg_drv.mutex);
279 	return 0;
280 }
281 
282 static void hp_attr_set_interface_remove(struct wmi_device *wdev)
283 {
284 	mutex_lock(&bioscfg_drv.mutex);
285 	mutex_unlock(&bioscfg_drv.mutex);
286 }
287 
288 static const struct wmi_device_id hp_attr_set_interface_id_table[] = {
289 	{ .guid_string = HP_WMI_BIOS_GUID},
290 	{ }
291 };
292 
293 static struct wmi_driver hp_attr_set_interface_driver = {
294 	.driver = {
295 		.name = DRIVER_NAME,
296 	},
297 	.probe = hp_attr_set_interface_probe,
298 	.remove = hp_attr_set_interface_remove,
299 	.id_table = hp_attr_set_interface_id_table,
300 };
301 
302 int hp_init_attr_set_interface(void)
303 {
304 	return wmi_driver_register(&hp_attr_set_interface_driver);
305 }
306 
307 void hp_exit_attr_set_interface(void)
308 {
309 	wmi_driver_unregister(&hp_attr_set_interface_driver);
310 }
311 
312 MODULE_DEVICE_TABLE(wmi, hp_attr_set_interface_id_table);
313