drivers/platform/chrome/wilco_ec/debugfs.c

   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
  22 struct 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 };
  29 static 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  */
  47 static 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(tmp, 16, &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
  95 static 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(buf, FORMATTED_BUFFER_SIZE, ppos,
 108                                         user_buf, count);
 109         if (kcount < 0)
 110                 return kcount;
 111
 112         ret = parse_hex_sentence(buf, kcount, 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(debug_info->ec, &msg);
 128         if (ret < 0)
 129                 return ret;
 130         debug_info->response_size = ret;
 131
 132         return count;
 133 }
 134
 135 static 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(debug_info->raw_data,
 142                                              debug_info->response_size,
 143                                              16, 1, debug_info->formatted_data,
 144                                              sizeof(debug_info->formatted_data),
 145                                              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(user_buf, count, ppos,
 151                                        debug_info->formatted_data, fmt_len);
 152 }
 153
 154 static 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
 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
 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  */
 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  */
 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  */
 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         if (!debug_info->dir)
 255                 return 0;
 256         debugfs_create_file("raw", 0644, debug_info->dir, NULL, &fops_raw);
 257         debugfs_create_file("h1_gpio", 0444, debug_info->dir, ec,
 258                             &fops_h1_gpio);
 259         debugfs_create_file("test_event", 0200, debug_info->dir, ec,
 260                             &fops_test_event);
 261
 262         return 0;
 263 }
 264
 265 static int wilco_ec_debugfs_remove(struct platform_device *pdev)
 266 {
 267         debugfs_remove_recursive(debug_info->dir);
 268
 269         return 0;
 270 }
 271
 272 static struct platform_driver wilco_ec_debugfs_driver = {
 273         .driver = {
 274                 .name = DRV_NAME,
 275         },
 276         .probe = wilco_ec_debugfs_probe,
 277         .remove = wilco_ec_debugfs_remove,
 278 };
 279
 280 module_platform_driver(wilco_ec_debugfs_driver);
 281
 282 MODULE_ALIAS("platform:" DRV_NAME);
 283 MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
 284 MODULE_LICENSE("GPL v2");
 285 MODULE_DESCRIPTION("Wilco EC debugfs driver");