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 */
17struct 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 */
38int 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
92out_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 */
119int 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
181out_free:
182	ret = hp_wmi_error_and_message(ret);
183
184	kfree(obj);
185	kfree(args);
186	return ret;
187}
188
189static 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 */
207void *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 */
246int 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
270out_free:
271	kfree(obj);
272	return ret;
273}
274
275static 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
282static 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
288static const struct wmi_device_id hp_attr_set_interface_id_table[] = {
289	{ .guid_string = HP_WMI_BIOS_GUID},
290	{ }
291};
292
293static 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
302int hp_init_attr_set_interface(void)
303{
304	return wmi_driver_register(&hp_attr_set_interface_driver);
305}
306
307void hp_exit_attr_set_interface(void)
308{
309	wmi_driver_unregister(&hp_attr_set_interface_driver);
310}
311
312MODULE_DEVICE_TABLE(wmi, hp_attr_set_interface_id_table);
313