// SPDX-License-Identifier: GPL-2.0 /* * debugfs attributes for Wilco EC * * Copyright 2019 Google LLC * * There is only one attribute used for debugging, called raw. * You can write a hexadecimal sentence to raw, and that series of bytes * will be sent to the EC. Then, you can read the bytes of response * by reading from raw. * * For writing: * Bytes 0-1 indicate the message type: * 00 F0 = Execute Legacy Command * 00 F2 = Read/Write NVRAM Property * Byte 2 provides the command code * Bytes 3+ consist of the data passed in the request * * When referencing the EC interface spec, byte 2 corresponds to MBOX[0], * byte 3 corresponds to MBOX[1], etc. * * At least three bytes are required, for the msg type and command, * with additional bytes optional for additional data. * * Example: * // Request EC info type 3 (EC firmware build date) * $ echo 00 f0 38 00 03 00 > raw * // View the result. The decoded ASCII result "12/21/18" is * // included after the raw hex. * $ cat raw * 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 .12/21/18.8... */ #include #include #include #include #include #include #define DRV_NAME "wilco-ec-debugfs" /* The 256 raw bytes will take up more space when represented as a hex string */ #define FORMATTED_BUFFER_SIZE (EC_MAILBOX_DATA_SIZE_EXTENDED * 4) struct wilco_ec_debugfs { struct wilco_ec_device *ec; struct dentry *dir; size_t response_size; u8 raw_data[EC_MAILBOX_DATA_SIZE_EXTENDED]; u8 formatted_data[FORMATTED_BUFFER_SIZE]; }; static struct wilco_ec_debugfs *debug_info; /** * parse_hex_sentence() - Convert a ascii hex representation into byte array. * @in: Input buffer of ascii. * @isize: Length of input buffer. * @out: Output buffer. * @osize: Length of output buffer, e.g. max number of bytes to parse. * * An valid input is a series of ascii hexadecimal numbers, separated by spaces. * An example valid input is * " 00 f2 0 000076 6 0 ff" * * If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE, * then the sentence is illegal, and parsing will fail. * * Return: Number of bytes parsed, or negative error code on failure. */ static int parse_hex_sentence(const char *in, int isize, u8 *out, int osize) { int n_parsed = 0; int word_start = 0; int word_end; int word_len; /* Temp buffer for holding a "word" of chars that represents one byte */ #define MAX_WORD_SIZE 16 char tmp[MAX_WORD_SIZE + 1]; u8 byte; while (word_start < isize && n_parsed < osize) { /* Find the start of the next word */ while (word_start < isize && isspace(in[word_start])) word_start++; /* reached the end of the input before next word? */ if (word_start >= isize) break; /* Find the end of this word */ word_end = word_start; while (word_end < isize && !isspace(in[word_end])) word_end++; /* Copy to a tmp NULL terminated string */ word_len = word_end - word_start; if (word_len > MAX_WORD_SIZE) return -EINVAL; memcpy(tmp, in + word_start, word_len); tmp[word_len] = '\0'; /* * Convert from hex string, place in output. If fails to parse, * just return -EINVAL because specific error code is only * relevant for this one word, returning it would be confusing. */ if (kstrtou8(tmp, 16, &byte)) return -EINVAL; out[n_parsed++] = byte; word_start = word_end; } return n_parsed; } /* The message type takes up two bytes*/ #define TYPE_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 2) static ssize_t raw_write(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) { char *buf = debug_info->formatted_data; struct wilco_ec_message msg; u8 request_data[TYPE_AND_DATA_SIZE]; ssize_t kcount; int ret; if (count > FORMATTED_BUFFER_SIZE) return -EINVAL; kcount = simple_write_to_buffer(buf, FORMATTED_BUFFER_SIZE, ppos, user_buf, count); if (kcount < 0) return kcount; ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE); if (ret < 0) return ret; /* Need at least two bytes for message type and one for command */ if (ret < 3) return -EINVAL; /* Clear response data buffer */ memset(debug_info->raw_data, '\0', EC_MAILBOX_DATA_SIZE_EXTENDED); msg.type = request_data[0] << 8 | request_data[1]; msg.flags = WILCO_EC_FLAG_RAW; msg.command = request_data[2]; msg.request_data = ret > 3 ? request_data + 3 : 0; msg.request_size = ret - 3; msg.response_data = debug_info->raw_data; msg.response_size = EC_MAILBOX_DATA_SIZE; /* Telemetry commands use extended response data */ if (msg.type == WILCO_EC_MSG_TELEMETRY_LONG) { msg.flags |= WILCO_EC_FLAG_EXTENDED_DATA; msg.response_size = EC_MAILBOX_DATA_SIZE_EXTENDED; } ret = wilco_ec_mailbox(debug_info->ec, &msg); if (ret < 0) return ret; debug_info->response_size = ret; return count; } static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { int fmt_len = 0; if (debug_info->response_size) { fmt_len = hex_dump_to_buffer(debug_info->raw_data, debug_info->response_size, 16, 1, debug_info->formatted_data, FORMATTED_BUFFER_SIZE, true); /* Only return response the first time it is read */ debug_info->response_size = 0; } return simple_read_from_buffer(user_buf, count, ppos, debug_info->formatted_data, fmt_len); } static const struct file_operations fops_raw = { .owner = THIS_MODULE, .read = raw_read, .write = raw_write, .llseek = no_llseek, }; /** * wilco_ec_debugfs_probe() - Create the debugfs node * @pdev: The platform device, probably created in core.c * * Try to create a debugfs node. If it fails, then we don't want to change * behavior at all, this is for debugging after all. Just fail silently. * * Return: 0 always. */ static int wilco_ec_debugfs_probe(struct platform_device *pdev) { struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent); debug_info = devm_kzalloc(&pdev->dev, sizeof(*debug_info), GFP_KERNEL); if (!debug_info) return 0; debug_info->ec = ec; debug_info->dir = debugfs_create_dir("wilco_ec", NULL); if (!debug_info->dir) return 0; debugfs_create_file("raw", 0644, debug_info->dir, NULL, &fops_raw); return 0; } static int wilco_ec_debugfs_remove(struct platform_device *pdev) { debugfs_remove_recursive(debug_info->dir); return 0; } static struct platform_driver wilco_ec_debugfs_driver = { .driver = { .name = DRV_NAME, }, .probe = wilco_ec_debugfs_probe, .remove = wilco_ec_debugfs_remove, }; module_platform_driver(wilco_ec_debugfs_driver); MODULE_ALIAS("platform:" DRV_NAME); MODULE_AUTHOR("Nick Crews "); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("Wilco EC debugfs driver");