lkml.org 
[lkml]   [2019]   [Jan]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v5 3/3] platform/chrome: Add support for raw commands in debugfs
Date
From: Duncan Laurie <dlaurie@google.com>

Add a debugfs attribute that allows sending raw commands to the EC.
This is useful for development and debug but should not be enabled
in a production environment.

Get the EC firmware build date
First send the request command
> echo 00 f0 38 00 03 00 > raw
Then read the result. "12/21/18" is in the middle of the response
> cat raw
00 31 32 2f 32 31 2f 31 38 00 00 0f 01 00 01 00 .12/21/18.......

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Acked-for-chrome-platform-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
---

Changes in v5:
- core now always continues regardless of debugfs failure
- mv documentation to file header
- Check for OOM
- rm unneeded check if debug_info is allocqated
- rm bogus comment
- add space around "+"
- rm WILCO_EC_FLAG_EXTENDED_DATA, that is already obvious from
wilco_ec_message.response_size

Changes in v4:
- Change debugfs driver to be a separate module
- Change me email to @chromium.org from @google.com
- Change CONFIG_WILCO_EC_SYSFS_RAW to
CONFIG_WILCO_EC_DEBUGFS

Changes in v3:
- Move the attribute to the debugfs system
- Move the implementation to debugfs.c
- Improve the raw hex parsing
- Encapsulate global variables in one object
- Add safety check when passing less than 3 bytes
- Move documentation to debugfs-wilco-ec

Changes in v2:
- Add sysfs documentation
- rm duplicate EC_MAILBOX_DATA_SIZE defs
- Make docstrings follow kernel style
- Fix tags in commit msg
- Move Kconfig to subdirectory
- Reading raw now includes ASCII translation

Documentation/ABI/testing/debugfs-wilco-ec | 23 +++
drivers/platform/chrome/wilco_ec/Kconfig | 9 +
drivers/platform/chrome/wilco_ec/Makefile | 2 +
drivers/platform/chrome/wilco_ec/core.c | 8 +
drivers/platform/chrome/wilco_ec/debugfs.c | 223 +++++++++++++++++++++
5 files changed, 265 insertions(+)
create mode 100644 Documentation/ABI/testing/debugfs-wilco-ec
create mode 100644 drivers/platform/chrome/wilco_ec/debugfs.c

diff --git a/Documentation/ABI/testing/debugfs-wilco-ec b/Documentation/ABI/testing/debugfs-wilco-ec
new file mode 100644
index 000000000000..6bf09e2d87e3
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-wilco-ec
@@ -0,0 +1,23 @@
+What: /sys/kernel/debug/wilco_ec/raw
+Date: January 2019
+KernelVersion: 4.19
+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...
diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig
index 20945a301ec6..56b871510c4d 100644
--- a/drivers/platform/chrome/wilco_ec/Kconfig
+++ b/drivers/platform/chrome/wilco_ec/Kconfig
@@ -9,3 +9,12 @@ 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 is disabled by default.
diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
index 03b32301dc61..063e7fb4ea17 100644
--- a/drivers/platform/chrome/wilco_ec/Makefile
+++ b/drivers/platform/chrome/wilco_ec/Makefile
@@ -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
diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
index 7dcb3bde132a..88d7e59a306e 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -71,6 +71,14 @@ 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 debugfs platform device that will get picked up by the
+ * debugfs driver. This platform device will get freed when its parent
+ * device dev is unregistered. Ignore failure.
+ */
+ platform_device_register_data(dev, "wilco-ec-debugfs",
+ PLATFORM_DEVID_AUTO, NULL, 0);
+
return 0;
}

diff --git a/drivers/platform/chrome/wilco_ec/debugfs.c b/drivers/platform/chrome/wilco_ec/debugfs.c
new file mode 100644
index 000000000000..449553514ea6
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/debugfs.c
@@ -0,0 +1,223 @@
+// 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
+ *
+ * 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 */
+ const static int 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 and the command takes a byte */
+#define CMDS_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 3)
+
+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[CMDS_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, CMDS_AND_DATA_SIZE);
+ if (ret < 0)
+ return ret;
+ /* Need at least three bytes for type and 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 : NULL;
+ 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.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,
+};
+
+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 -ENOMEM;
+ debug_info->ec = ec;
+ debug_info->dir = debugfs_create_dir("wilco_ec", NULL);
+ 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");
--
2.20.1.495.gaa96b0ce6b-goog

\
 
 \ /
  Last update: 2019-01-31 00:19    [W:0.048 / U:5.468 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site