[PATCH v3 3/9] platform/chrome: Add support for raw commands in debugfs
From: Nick Crews
Date: Fri Jan 18 2019 - 19:15:07 EST
From: Duncan Laurie <dlaurie@xxxxxxxxxx>
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.
Turn the keyboard global mic mute led on
> echo 00 f2 01 76 06 00 00 01 01 > /sys/kernel/debug/wilco_ec/raw
Turn the keyboard global mic mute led off
> echo 00 f2 01 76 06 00 00 01 00 > /sys/kernel/debug/wilco_ec/raw
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@xxxxxxxxxx>
Signed-off-by: Nick Crews <ncrews@xxxxxxxxxxxx>
---
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 | 17 ++
drivers/platform/chrome/wilco_ec/debugfs.c | 218 +++++++++++++++++++++
include/linux/platform_data/wilco-ec.h | 3 +
6 files changed, 271 insertions(+), 1 deletion(-)
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..90bc3fe08dff
--- /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
+
+ 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...
+
+ At least three bytes are required, for the msg type and command,
+ with additional bytes optional for additional data.
diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig
index f8e6c9e8c5cd..0bd84c98b79b 100644
--- a/drivers/platform/chrome/wilco_ec/Kconfig
+++ b/drivers/platform/chrome/wilco_ec/Kconfig
@@ -21,4 +21,13 @@ config WILCO_EC
To compile this driver as a module, choose M here: the
module will be called wilco_ec.
+config WILCO_EC_SYSFS_RAW
+ bool "Enable raw access to EC via sysfs"
+ depends on WILCO_EC
+ help
+ If you say Y here, you get support for sending raw commands to
+ the Wilco EC via sysfs. 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.
+
endif # WILCO_EC_PLATFORM
diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
index 03b32301dc61..86d0457d85ea 100644
--- a/drivers/platform/chrome/wilco_ec/Makefile
+++ b/drivers/platform/chrome/wilco_ec/Makefile
@@ -1,4 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
-wilco_ec-objs := core.o mailbox.o
+wilco_ec-objs := core.o mailbox.o debugfs.o
obj-$(CONFIG_WILCO_EC) += wilco_ec.o
diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
index 13fe21dd235a..749fd6a36057 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -34,6 +34,7 @@ static int wilco_ec_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct wilco_ec_device *ec;
+ int ret;
ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
if (!ec)
@@ -61,11 +62,27 @@ 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);
+ /* add debugfs attributes */
+ ret = wilco_ec_debugfs_init(ec);
+ if (ret) {
+ dev_err(dev, "Failed to create debugfs attributes\n");
+ goto destroy_mec;
+ }
+
return 0;
+
+destroy_mec:
+ cros_ec_lpc_mec_destroy();
+ return ret;
}
static int wilco_ec_remove(struct platform_device *pdev)
{
+ struct wilco_ec_device *ec = platform_get_drvdata(pdev);
+
+ /* remove debugfs attributes */
+ wilco_ec_debugfs_remove(ec);
+
/* Teardown cros_ec interface */
cros_ec_lpc_mec_destroy();
diff --git a/drivers/platform/chrome/wilco_ec/debugfs.c b/drivers/platform/chrome/wilco_ec/debugfs.c
new file mode 100644
index 000000000000..46b0bf3fdf39
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/debugfs.c
@@ -0,0 +1,218 @@
+// 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.
+ */
+
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/fs.h>
+#include <linux/platform_data/wilco-ec.h>
+
+#ifdef CONFIG_WILCO_EC_SYSFS_RAW
+
+#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
+ *
+ * If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE,
+ * then the sentence is illegal.
+ *
+ * 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;
+}
+
+#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) {
+ 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;
+}
+
+/**
+ * wilco_ec_raw_show() - Show result from previous call to raw_store()
+ * @dev: Device representing the EC
+ * @attr: The attribute in question
+ * @buf: Output buffer to be filled
+ *
+ * Example usage:
+ * // Call raw_store(), read EC info type 3 (EC firmware build date)
+ * # echo 00 f0 38 00 03 00 > raw
+ * // Call this function, 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.../.
+ *
+ * Return: Number of bytes written to output, negative error code on failure
+ */
+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,
+};
+
+int wilco_ec_debugfs_init(struct wilco_ec_device *ec)
+{
+ debug_info = devm_kzalloc(ec->dev, sizeof(*debug_info), GFP_KERNEL);
+ if (!debug_info)
+ return -ENOMEM;
+ debug_info->ec = ec;
+
+ debug_info->dir = debugfs_create_dir("wilco_ec", NULL);
+ if (!debug_info->dir)
+ return -ENOMEM;
+
+ if (!debugfs_create_file("raw", 0644, debug_info->dir,
+ NULL, &fops_raw)) {
+ debugfs_remove_recursive(debug_info->dir);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+void wilco_ec_debugfs_remove(struct wilco_ec_device *ec)
+{
+ if (debug_info) {
+ debugfs_remove_recursive(debug_info->dir);
+ devm_kfree(ec->dev, debug_info); /* needed? */
+ }
+}
+
+#else /* CONFIG_WILCO_EC_SYSFS_RAW */
+
+int wilco_ec_debugfs_init(struct wilco_ec_device *ec)
+{
+ return 0;
+}
+
+void wilco_ec_debugfs_remove(struct wilco_ec_device *ec) {}
+
+#endif /* CONFIG_WILCO_EC_SYSFS_RAW */
diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
index 5477b8802f81..3298eabe73bc 100644
--- a/include/linux/platform_data/wilco-ec.h
+++ b/include/linux/platform_data/wilco-ec.h
@@ -135,4 +135,7 @@ struct wilco_ec_response {
*/
int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg);
+int wilco_ec_debugfs_init(struct wilco_ec_device *ec);
+void wilco_ec_debugfs_remove(struct wilco_ec_device *ec);
+
#endif /* WILCO_EC_H */
--
2.20.1.321.g9e740568ce-goog