1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * debugfs attributes for Wilco EC
4 *
5 * Copyright 2019 Google LLC
6 *
7 * See Documentation/ABI/testing/debugfs-wilco-ec for usage.
8 */
9
10 #include <linux/ctype.h>
11 #include <linux/debugfs.h>
12 #include <linux/fs.h>
13 #include <linux/mod_devicetable.h>
14 #include <linux/module.h>
15 #include <linux/platform_data/wilco-ec.h>
16 #include <linux/platform_device.h>
17
18 #define DRV_NAME "wilco-ec-debugfs"
19
20 /* The raw bytes will take up more space when represented as a hex string */
21 #define FORMATTED_BUFFER_SIZE (EC_MAILBOX_DATA_SIZE * 4)
22
23 struct wilco_ec_debugfs {
24 struct wilco_ec_device *ec;
25 struct dentry *dir;
26 size_t response_size;
27 u8 raw_data[EC_MAILBOX_DATA_SIZE];
28 u8 formatted_data[FORMATTED_BUFFER_SIZE];
29 };
30 static struct wilco_ec_debugfs *debug_info;
31
32 /**
33 * parse_hex_sentence() - Convert a ascii hex representation into byte array.
34 * @in: Input buffer of ascii.
35 * @isize: Length of input buffer.
36 * @out: Output buffer.
37 * @osize: Length of output buffer, e.g. max number of bytes to parse.
38 *
39 * An valid input is a series of ascii hexadecimal numbers, separated by spaces.
40 * An example valid input is
41 * " 00 f2 0 000076 6 0 ff"
42 *
43 * If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE,
44 * then the sentence is illegal, and parsing will fail.
45 *
46 * Return: Number of bytes parsed, or negative error code on failure.
47 */
parse_hex_sentence(const char * in,int isize,u8 * out,int osize)48 static int parse_hex_sentence(const char *in, int isize, u8 *out, int osize)
49 {
50 int n_parsed = 0;
51 int word_start = 0;
52 int word_end;
53 int word_len;
54 /* Temp buffer for holding a "word" of chars that represents one byte */
55 #define MAX_WORD_SIZE 16
56 char tmp[MAX_WORD_SIZE + 1];
57 u8 byte;
58
59 while (word_start < isize && n_parsed < osize) {
60 /* Find the start of the next word */
61 while (word_start < isize && isspace(in[word_start]))
62 word_start++;
63 /* reached the end of the input before next word? */
64 if (word_start >= isize)
65 break;
66
67 /* Find the end of this word */
68 word_end = word_start;
69 while (word_end < isize && !isspace(in[word_end]))
70 word_end++;
71
72 /* Copy to a tmp NULL terminated string */
73 word_len = word_end - word_start;
74 if (word_len > MAX_WORD_SIZE)
75 return -EINVAL;
76 memcpy(tmp, in + word_start, word_len);
77 tmp[word_len] = '\0';
78
79 /*
80 * Convert from hex string, place in output. If fails to parse,
81 * just return -EINVAL because specific error code is only
82 * relevant for this one word, returning it would be confusing.
83 */
84 if (kstrtou8(tmp, 16, &byte))
85 return -EINVAL;
86 out[n_parsed++] = byte;
87
88 word_start = word_end;
89 }
90 return n_parsed;
91 }
92
93 /* The message type takes up two bytes*/
94 #define TYPE_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 2)
95
raw_write(struct file * file,const char __user * user_buf,size_t count,loff_t * ppos)96 static ssize_t raw_write(struct file *file, const char __user *user_buf,
97 size_t count, loff_t *ppos)
98 {
99 char *buf = debug_info->formatted_data;
100 struct wilco_ec_message msg;
101 u8 request_data[TYPE_AND_DATA_SIZE];
102 ssize_t kcount;
103 int ret;
104
105 if (count > FORMATTED_BUFFER_SIZE)
106 return -EINVAL;
107
108 kcount = simple_write_to_buffer(buf, FORMATTED_BUFFER_SIZE, ppos,
109 user_buf, count);
110 if (kcount < 0)
111 return kcount;
112
113 ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE);
114 if (ret < 0)
115 return ret;
116 /* Need at least two bytes for message type and one byte of data */
117 if (ret < 3)
118 return -EINVAL;
119
120 msg.type = request_data[0] << 8 | request_data[1];
121 msg.flags = 0;
122 msg.request_data = request_data + 2;
123 msg.request_size = ret - 2;
124 memset(debug_info->raw_data, 0, sizeof(debug_info->raw_data));
125 msg.response_data = debug_info->raw_data;
126 msg.response_size = EC_MAILBOX_DATA_SIZE;
127
128 ret = wilco_ec_mailbox(debug_info->ec, &msg);
129 if (ret < 0)
130 return ret;
131 debug_info->response_size = ret;
132
133 return count;
134 }
135
raw_read(struct file * file,char __user * user_buf,size_t count,loff_t * ppos)136 static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count,
137 loff_t *ppos)
138 {
139 int fmt_len = 0;
140
141 if (debug_info->response_size) {
142 fmt_len = hex_dump_to_buffer(debug_info->raw_data,
143 debug_info->response_size,
144 16, 1, debug_info->formatted_data,
145 sizeof(debug_info->formatted_data),
146 true);
147 /* Only return response the first time it is read */
148 debug_info->response_size = 0;
149 }
150
151 return simple_read_from_buffer(user_buf, count, ppos,
152 debug_info->formatted_data, fmt_len);
153 }
154
155 static const struct file_operations fops_raw = {
156 .owner = THIS_MODULE,
157 .read = raw_read,
158 .write = raw_write,
159 };
160
161 #define CMD_KB_CHROME 0x88
162 #define SUB_CMD_H1_GPIO 0x0A
163 #define SUB_CMD_TEST_EVENT 0x0B
164
165 struct ec_request {
166 u8 cmd; /* Always CMD_KB_CHROME */
167 u8 reserved;
168 u8 sub_cmd;
169 } __packed;
170
171 struct ec_response {
172 u8 status; /* 0 if allowed */
173 u8 val;
174 } __packed;
175
send_ec_cmd(struct wilco_ec_device * ec,u8 sub_cmd,u8 * out_val)176 static int send_ec_cmd(struct wilco_ec_device *ec, u8 sub_cmd, u8 *out_val)
177 {
178 struct ec_request rq;
179 struct ec_response rs;
180 struct wilco_ec_message msg;
181 int ret;
182
183 memset(&rq, 0, sizeof(rq));
184 rq.cmd = CMD_KB_CHROME;
185 rq.sub_cmd = sub_cmd;
186
187 memset(&msg, 0, sizeof(msg));
188 msg.type = WILCO_EC_MSG_LEGACY;
189 msg.request_data = &rq;
190 msg.request_size = sizeof(rq);
191 msg.response_data = &rs;
192 msg.response_size = sizeof(rs);
193 ret = wilco_ec_mailbox(ec, &msg);
194 if (ret < 0)
195 return ret;
196 if (rs.status)
197 return -EIO;
198
199 *out_val = rs.val;
200
201 return 0;
202 }
203
204 /**
205 * h1_gpio_get() - Gets h1 gpio status.
206 * @arg: The wilco EC device.
207 * @val: BIT(0)=ENTRY_TO_FACT_MODE, BIT(1)=SPI_CHROME_SEL
208 */
h1_gpio_get(void * arg,u64 * val)209 static int h1_gpio_get(void *arg, u64 *val)
210 {
211 int ret;
212
213 ret = send_ec_cmd(arg, SUB_CMD_H1_GPIO, (u8 *)val);
214 if (ret == 0)
215 *val &= 0xFF;
216 return ret;
217 }
218
219 DEFINE_DEBUGFS_ATTRIBUTE(fops_h1_gpio, h1_gpio_get, NULL, "0x%02llx\n");
220
221 /**
222 * test_event_set() - Sends command to EC to cause an EC test event.
223 * @arg: The wilco EC device.
224 * @val: unused.
225 */
test_event_set(void * arg,u64 val)226 static int test_event_set(void *arg, u64 val)
227 {
228 u8 ret;
229
230 return send_ec_cmd(arg, SUB_CMD_TEST_EVENT, &ret);
231 }
232
233 /* Format is unused since it is only required for get method which is NULL */
234 DEFINE_DEBUGFS_ATTRIBUTE(fops_test_event, NULL, test_event_set, "%llu\n");
235
236 /**
237 * wilco_ec_debugfs_probe() - Create the debugfs node
238 * @pdev: The platform device, probably created in core.c
239 *
240 * Try to create a debugfs node. If it fails, then we don't want to change
241 * behavior at all, this is for debugging after all. Just fail silently.
242 *
243 * Return: 0 always.
244 */
wilco_ec_debugfs_probe(struct platform_device * pdev)245 static int wilco_ec_debugfs_probe(struct platform_device *pdev)
246 {
247 struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
248
249 debug_info = devm_kzalloc(&pdev->dev, sizeof(*debug_info), GFP_KERNEL);
250 if (!debug_info)
251 return 0;
252 debug_info->ec = ec;
253 debug_info->dir = debugfs_create_dir("wilco_ec", NULL);
254 debugfs_create_file("raw", 0644, debug_info->dir, NULL, &fops_raw);
255 debugfs_create_file("h1_gpio", 0444, debug_info->dir, ec,
256 &fops_h1_gpio);
257 debugfs_create_file("test_event", 0200, debug_info->dir, ec,
258 &fops_test_event);
259
260 return 0;
261 }
262
wilco_ec_debugfs_remove(struct platform_device * pdev)263 static void wilco_ec_debugfs_remove(struct platform_device *pdev)
264 {
265 debugfs_remove_recursive(debug_info->dir);
266 }
267
268 static const struct platform_device_id wilco_ec_debugfs_id[] = {
269 { DRV_NAME, 0 },
270 {}
271 };
272 MODULE_DEVICE_TABLE(platform, wilco_ec_debugfs_id);
273
274 static struct platform_driver wilco_ec_debugfs_driver = {
275 .driver = {
276 .name = DRV_NAME,
277 },
278 .probe = wilco_ec_debugfs_probe,
279 .remove_new = wilco_ec_debugfs_remove,
280 .id_table = wilco_ec_debugfs_id,
281 };
282
283 module_platform_driver(wilco_ec_debugfs_driver);
284
285 MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
286 MODULE_LICENSE("GPL v2");
287 MODULE_DESCRIPTION("Wilco EC debugfs driver");
288