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/module.h>
14#include <linux/platform_data/wilco-ec.h>
15#include <linux/platform_device.h>
16
17#define DRV_NAME "wilco-ec-debugfs"
18
19/* The raw bytes will take up more space when represented as a hex string */
20#define FORMATTED_BUFFER_SIZE (EC_MAILBOX_DATA_SIZE * 4)
21
22struct wilco_ec_debugfs {
23 struct wilco_ec_device *ec;
24 struct dentry *dir;
25 size_t response_size;
26 u8 raw_data[EC_MAILBOX_DATA_SIZE];
27 u8 formatted_data[FORMATTED_BUFFER_SIZE];
28};
29static struct wilco_ec_debugfs *debug_info;
30
31/**
32 * parse_hex_sentence() - Convert a ascii hex representation into byte array.
33 * @in: Input buffer of ascii.
34 * @isize: Length of input buffer.
35 * @out: Output buffer.
36 * @osize: Length of output buffer, e.g. max number of bytes to parse.
37 *
38 * An valid input is a series of ascii hexadecimal numbers, separated by spaces.
39 * An example valid input is
40 * " 00 f2 0 000076 6 0 ff"
41 *
42 * If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE,
43 * then the sentence is illegal, and parsing will fail.
44 *
45 * Return: Number of bytes parsed, or negative error code on failure.
46 */
47static int parse_hex_sentence(const char *in, int isize, u8 *out, int osize)
48{
49 int n_parsed = 0;
50 int word_start = 0;
51 int word_end;
52 int word_len;
53 /* Temp buffer for holding a "word" of chars that represents one byte */
54 #define MAX_WORD_SIZE 16
55 char tmp[MAX_WORD_SIZE + 1];
56 u8 byte;
57
58 while (word_start < isize && n_parsed < osize) {
59 /* Find the start of the next word */
60 while (word_start < isize && isspace(in[word_start]))
61 word_start++;
62 /* reached the end of the input before next word? */
63 if (word_start >= isize)
64 break;
65
66 /* Find the end of this word */
67 word_end = word_start;
68 while (word_end < isize && !isspace(in[word_end]))
69 word_end++;
70
71 /* Copy to a tmp NULL terminated string */
72 word_len = word_end - word_start;
73 if (word_len > MAX_WORD_SIZE)
74 return -EINVAL;
75 memcpy(tmp, in + word_start, word_len);
76 tmp[word_len] = '\0';
77
78 /*
79 * Convert from hex string, place in output. If fails to parse,
80 * just return -EINVAL because specific error code is only
81 * relevant for this one word, returning it would be confusing.
82 */
83 if (kstrtou8(s: tmp, base: 16, res: &byte))
84 return -EINVAL;
85 out[n_parsed++] = byte;
86
87 word_start = word_end;
88 }
89 return n_parsed;
90}
91
92/* The message type takes up two bytes*/
93#define TYPE_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 2)
94
95static ssize_t raw_write(struct file *file, const char __user *user_buf,
96 size_t count, loff_t *ppos)
97{
98 char *buf = debug_info->formatted_data;
99 struct wilco_ec_message msg;
100 u8 request_data[TYPE_AND_DATA_SIZE];
101 ssize_t kcount;
102 int ret;
103
104 if (count > FORMATTED_BUFFER_SIZE)
105 return -EINVAL;
106
107 kcount = simple_write_to_buffer(to: buf, FORMATTED_BUFFER_SIZE, ppos,
108 from: user_buf, count);
109 if (kcount < 0)
110 return kcount;
111
112 ret = parse_hex_sentence(in: buf, isize: kcount, out: request_data, TYPE_AND_DATA_SIZE);
113 if (ret < 0)
114 return ret;
115 /* Need at least two bytes for message type and one byte of data */
116 if (ret < 3)
117 return -EINVAL;
118
119 msg.type = request_data[0] << 8 | request_data[1];
120 msg.flags = 0;
121 msg.request_data = request_data + 2;
122 msg.request_size = ret - 2;
123 memset(debug_info->raw_data, 0, sizeof(debug_info->raw_data));
124 msg.response_data = debug_info->raw_data;
125 msg.response_size = EC_MAILBOX_DATA_SIZE;
126
127 ret = wilco_ec_mailbox(ec: debug_info->ec, msg: &msg);
128 if (ret < 0)
129 return ret;
130 debug_info->response_size = ret;
131
132 return count;
133}
134
135static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count,
136 loff_t *ppos)
137{
138 int fmt_len = 0;
139
140 if (debug_info->response_size) {
141 fmt_len = hex_dump_to_buffer(buf: debug_info->raw_data,
142 len: debug_info->response_size,
143 rowsize: 16, groupsize: 1, linebuf: debug_info->formatted_data,
144 linebuflen: sizeof(debug_info->formatted_data),
145 ascii: true);
146 /* Only return response the first time it is read */
147 debug_info->response_size = 0;
148 }
149
150 return simple_read_from_buffer(to: user_buf, count, ppos,
151 from: debug_info->formatted_data, available: fmt_len);
152}
153
154static const struct file_operations fops_raw = {
155 .owner = THIS_MODULE,
156 .read = raw_read,
157 .write = raw_write,
158 .llseek = no_llseek,
159};
160
161#define CMD_KB_CHROME 0x88
162#define SUB_CMD_H1_GPIO 0x0A
163#define SUB_CMD_TEST_EVENT 0x0B
164
165struct ec_request {
166 u8 cmd; /* Always CMD_KB_CHROME */
167 u8 reserved;
168 u8 sub_cmd;
169} __packed;
170
171struct ec_response {
172 u8 status; /* 0 if allowed */
173 u8 val;
174} __packed;
175
176static 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: &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 */
209static int h1_gpio_get(void *arg, u64 *val)
210{
211 int ret;
212
213 ret = send_ec_cmd(ec: arg, SUB_CMD_H1_GPIO, out_val: (u8 *)val);
214 if (ret == 0)
215 *val &= 0xFF;
216 return ret;
217}
218
219DEFINE_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 */
226static int test_event_set(void *arg, u64 val)
227{
228 u8 ret;
229
230 return send_ec_cmd(ec: arg, SUB_CMD_TEST_EVENT, out_val: &ret);
231}
232
233/* Format is unused since it is only required for get method which is NULL */
234DEFINE_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 */
245static int wilco_ec_debugfs_probe(struct platform_device *pdev)
246{
247 struct wilco_ec_device *ec = dev_get_drvdata(dev: pdev->dev.parent);
248
249 debug_info = devm_kzalloc(dev: &pdev->dev, size: sizeof(*debug_info), GFP_KERNEL);
250 if (!debug_info)
251 return 0;
252 debug_info->ec = ec;
253 debug_info->dir = debugfs_create_dir(name: "wilco_ec", NULL);
254 debugfs_create_file(name: "raw", mode: 0644, parent: debug_info->dir, NULL, fops: &fops_raw);
255 debugfs_create_file(name: "h1_gpio", mode: 0444, parent: debug_info->dir, data: ec,
256 fops: &fops_h1_gpio);
257 debugfs_create_file(name: "test_event", mode: 0200, parent: debug_info->dir, data: ec,
258 fops: &fops_test_event);
259
260 return 0;
261}
262
263static void wilco_ec_debugfs_remove(struct platform_device *pdev)
264{
265 debugfs_remove_recursive(dentry: debug_info->dir);
266}
267
268static struct platform_driver wilco_ec_debugfs_driver = {
269 .driver = {
270 .name = DRV_NAME,
271 },
272 .probe = wilco_ec_debugfs_probe,
273 .remove_new = wilco_ec_debugfs_remove,
274};
275
276module_platform_driver(wilco_ec_debugfs_driver);
277
278MODULE_ALIAS("platform:" DRV_NAME);
279MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
280MODULE_LICENSE("GPL v2");
281MODULE_DESCRIPTION("Wilco EC debugfs driver");
282

source code of linux/drivers/platform/chrome/wilco_ec/debugfs.c