platform/chrome: wilco_ec: Add support for raw commands in debugfs (b787bb12) · Commits · 戴 / test

Documentation/ABI/testing/debugfs-wilco-ec

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		What: /sys/kernel/debug/wilco_ec/raw
		Date: January 2019
		KernelVersion: 5.1
		Description:
		Write and read raw mailbox commands to the EC.

		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

		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...

drivers/platform/chrome/wilco_ec/Kconfig

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		@@ -8,3 +8,13 @@ config WILCO_EC

		To compile this driver as a module, choose M here: the
		module will be called wilco_ec.

		config WILCO_EC_DEBUGFS
		tristate "Enable raw access to EC via debugfs"
		depends on WILCO_EC
		help
		If you say Y here, you get support for sending raw commands to
		the Wilco EC via debugfs. These commands do not do any byte
		manipulation and allow for testing arbitrary commands. This
		interface is intended for debug only and will not be present
		on production devices.

drivers/platform/chrome/wilco_ec/Makefile

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		@@ -2,3 +2,5 @@

		wilco_ec-objs := core.o mailbox.o
		obj-$(CONFIG_WILCO_EC) += wilco_ec.o
		wilco_ec_debugfs-objs := debugfs.o
		obj-$(CONFIG_WILCO_EC_DEBUGFS) += wilco_ec_debugfs.o

drivers/platform/chrome/wilco_ec/core.c

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		@@ -69,11 +69,25 @@ static int wilco_ec_probe(struct platform_device *pdev)
		cros_ec_lpc_mec_init(ec->io_packet->start,
		ec->io_packet->start + EC_MAILBOX_DATA_SIZE);

		/*
		* Register a child device that will be found by the debugfs driver.
		* Ignore failure.
		*/
		ec->debugfs_pdev = platform_device_register_data(dev,
		"wilco-ec-debugfs",
		PLATFORM_DEVID_AUTO,
		NULL, 0);

		return 0;
		}

		static int wilco_ec_remove(struct platform_device *pdev)
		{
		struct wilco_ec_device *ec = platform_get_drvdata(pdev);

		if (ec->debugfs_pdev)
		platform_device_unregister(ec->debugfs_pdev);

		/* Teardown cros_ec interface */
		cros_ec_lpc_mec_destroy();

drivers/platform/chrome/wilco_ec/debugfs.c

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		// 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 <linux/ctype.h>
		#include <linux/debugfs.h>
		#include <linux/fs.h>
		#include <linux/module.h>
		#include <linux/platform_data/wilco-ec.h>
		#include <linux/platform_device.h>

		#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 <ncrews@chromium.org>");
		MODULE_LICENSE("GPL v2");
		MODULE_DESCRIPTION("Wilco EC debugfs driver");

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