1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * debugfs attributes for Wilco EC 4 * 5 * Copyright 2019 Google LLC 6 * 7 * There is only one attribute used for debugging, called raw. 8 * You can write a hexadecimal sentence to raw, and that series of bytes 9 * will be sent to the EC. Then, you can read the bytes of response 10 * by reading from raw. 11 * 12 * For writing: 13 * Bytes 0-1 indicate the message type: 14 * 00 F0 = Execute Legacy Command 15 * 00 F2 = Read/Write NVRAM Property 16 * Byte 2 provides the command code 17 * Bytes 3+ consist of the data passed in the request 18 * 19 * When referencing the EC interface spec, byte 2 corresponds to MBOX[0], 20 * byte 3 corresponds to MBOX[1], etc. 21 * 22 * At least three bytes are required, for the msg type and command, 23 * with additional bytes optional for additional data. 24 * 25 * Example: 26 * // Request EC info type 3 (EC firmware build date) 27 * $ echo 00 f0 38 00 03 00 > raw 28 * // View the result. The decoded ASCII result "12/21/18" is 29 * // included after the raw hex. 30 * $ cat raw 31 * 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 .12/21/18.8... 32 */ 33 34 #include <linux/ctype.h> 35 #include <linux/debugfs.h> 36 #include <linux/fs.h> 37 #include <linux/module.h> 38 #include <linux/platform_data/wilco-ec.h> 39 #include <linux/platform_device.h> 40 41 #define DRV_NAME "wilco-ec-debugfs" 42 43 /* The 256 raw bytes will take up more space when represented as a hex string */ 44 #define FORMATTED_BUFFER_SIZE (EC_MAILBOX_DATA_SIZE_EXTENDED * 4) 45 46 struct wilco_ec_debugfs { 47 struct wilco_ec_device *ec; 48 struct dentry *dir; 49 size_t response_size; 50 u8 raw_data[EC_MAILBOX_DATA_SIZE_EXTENDED]; 51 u8 formatted_data[FORMATTED_BUFFER_SIZE]; 52 }; 53 static struct wilco_ec_debugfs *debug_info; 54 55 /** 56 * parse_hex_sentence() - Convert a ascii hex representation into byte array. 57 * @in: Input buffer of ascii. 58 * @isize: Length of input buffer. 59 * @out: Output buffer. 60 * @osize: Length of output buffer, e.g. max number of bytes to parse. 61 * 62 * An valid input is a series of ascii hexadecimal numbers, separated by spaces. 63 * An example valid input is 64 * " 00 f2 0 000076 6 0 ff" 65 * 66 * If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE, 67 * then the sentence is illegal, and parsing will fail. 68 * 69 * Return: Number of bytes parsed, or negative error code on failure. 70 */ 71 static int parse_hex_sentence(const char *in, int isize, u8 *out, int osize) 72 { 73 int n_parsed = 0; 74 int word_start = 0; 75 int word_end; 76 int word_len; 77 /* Temp buffer for holding a "word" of chars that represents one byte */ 78 #define MAX_WORD_SIZE 16 79 char tmp[MAX_WORD_SIZE + 1]; 80 u8 byte; 81 82 while (word_start < isize && n_parsed < osize) { 83 /* Find the start of the next word */ 84 while (word_start < isize && isspace(in[word_start])) 85 word_start++; 86 /* reached the end of the input before next word? */ 87 if (word_start >= isize) 88 break; 89 90 /* Find the end of this word */ 91 word_end = word_start; 92 while (word_end < isize && !isspace(in[word_end])) 93 word_end++; 94 95 /* Copy to a tmp NULL terminated string */ 96 word_len = word_end - word_start; 97 if (word_len > MAX_WORD_SIZE) 98 return -EINVAL; 99 memcpy(tmp, in + word_start, word_len); 100 tmp[word_len] = '\0'; 101 102 /* 103 * Convert from hex string, place in output. If fails to parse, 104 * just return -EINVAL because specific error code is only 105 * relevant for this one word, returning it would be confusing. 106 */ 107 if (kstrtou8(tmp, 16, &byte)) 108 return -EINVAL; 109 out[n_parsed++] = byte; 110 111 word_start = word_end; 112 } 113 return n_parsed; 114 } 115 116 /* The message type takes up two bytes*/ 117 #define TYPE_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 2) 118 119 static ssize_t raw_write(struct file *file, const char __user *user_buf, 120 size_t count, loff_t *ppos) 121 { 122 char *buf = debug_info->formatted_data; 123 struct wilco_ec_message msg; 124 u8 request_data[TYPE_AND_DATA_SIZE]; 125 ssize_t kcount; 126 int ret; 127 128 if (count > FORMATTED_BUFFER_SIZE) 129 return -EINVAL; 130 131 kcount = simple_write_to_buffer(buf, FORMATTED_BUFFER_SIZE, ppos, 132 user_buf, count); 133 if (kcount < 0) 134 return kcount; 135 136 ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE); 137 if (ret < 0) 138 return ret; 139 /* Need at least two bytes for message type and one for command */ 140 if (ret < 3) 141 return -EINVAL; 142 143 /* Clear response data buffer */ 144 memset(debug_info->raw_data, '\0', EC_MAILBOX_DATA_SIZE_EXTENDED); 145 146 msg.type = request_data[0] << 8 | request_data[1]; 147 msg.flags = WILCO_EC_FLAG_RAW; 148 msg.command = request_data[2]; 149 msg.request_data = ret > 3 ? request_data + 3 : 0; 150 msg.request_size = ret - 3; 151 msg.response_data = debug_info->raw_data; 152 msg.response_size = EC_MAILBOX_DATA_SIZE; 153 154 /* Telemetry commands use extended response data */ 155 if (msg.type == WILCO_EC_MSG_TELEMETRY_LONG) { 156 msg.flags |= WILCO_EC_FLAG_EXTENDED_DATA; 157 msg.response_size = EC_MAILBOX_DATA_SIZE_EXTENDED; 158 } 159 160 ret = wilco_ec_mailbox(debug_info->ec, &msg); 161 if (ret < 0) 162 return ret; 163 debug_info->response_size = ret; 164 165 return count; 166 } 167 168 static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count, 169 loff_t *ppos) 170 { 171 int fmt_len = 0; 172 173 if (debug_info->response_size) { 174 fmt_len = hex_dump_to_buffer(debug_info->raw_data, 175 debug_info->response_size, 176 16, 1, debug_info->formatted_data, 177 FORMATTED_BUFFER_SIZE, true); 178 /* Only return response the first time it is read */ 179 debug_info->response_size = 0; 180 } 181 182 return simple_read_from_buffer(user_buf, count, ppos, 183 debug_info->formatted_data, fmt_len); 184 } 185 186 static const struct file_operations fops_raw = { 187 .owner = THIS_MODULE, 188 .read = raw_read, 189 .write = raw_write, 190 .llseek = no_llseek, 191 }; 192 193 /** 194 * wilco_ec_debugfs_probe() - Create the debugfs node 195 * @pdev: The platform device, probably created in core.c 196 * 197 * Try to create a debugfs node. If it fails, then we don't want to change 198 * behavior at all, this is for debugging after all. Just fail silently. 199 * 200 * Return: 0 always. 201 */ 202 static int wilco_ec_debugfs_probe(struct platform_device *pdev) 203 { 204 struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 205 206 debug_info = devm_kzalloc(&pdev->dev, sizeof(*debug_info), GFP_KERNEL); 207 if (!debug_info) 208 return 0; 209 debug_info->ec = ec; 210 debug_info->dir = debugfs_create_dir("wilco_ec", NULL); 211 if (!debug_info->dir) 212 return 0; 213 debugfs_create_file("raw", 0644, debug_info->dir, NULL, &fops_raw); 214 215 return 0; 216 } 217 218 static int wilco_ec_debugfs_remove(struct platform_device *pdev) 219 { 220 debugfs_remove_recursive(debug_info->dir); 221 222 return 0; 223 } 224 225 static struct platform_driver wilco_ec_debugfs_driver = { 226 .driver = { 227 .name = DRV_NAME, 228 }, 229 .probe = wilco_ec_debugfs_probe, 230 .remove = wilco_ec_debugfs_remove, 231 }; 232 233 module_platform_driver(wilco_ec_debugfs_driver); 234 235 MODULE_ALIAS("platform:" DRV_NAME); 236 MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>"); 237 MODULE_LICENSE("GPL v2"); 238 MODULE_DESCRIPTION("Wilco EC debugfs driver"); 239