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Subject[PATCH v2 4/9] platform/chrome: Add support for raw commands in sysfs
From
From: Duncan Laurie <dlaurie@google.com>

Add a sysfs 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.

> echo 00 f0 38 00 03 00 > /sys/bus/platform/devices/GOOG000C\:00/raw
> cat /sys/bus/platform/devices/GOOG000C\:00/raw
00 37 33 38 65 64 00...

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@google.com>
---

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

.../ABI/testing/sysfs-platform-wilcoec | 21 ++++
drivers/platform/chrome/wilco_ec/Kconfig | 9 ++
drivers/platform/chrome/wilco_ec/legacy.c | 99 +++++++++++++++++++
drivers/platform/chrome/wilco_ec/legacy.h | 46 +++++++++
drivers/platform/chrome/wilco_ec/sysfs.c | 6 ++
5 files changed, 181 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-platform-wilcoec b/Documentation/ABI/testing/sysfs-platform-wilcoec
index 09552338c160..cac2cf11835f 100644
--- a/Documentation/ABI/testing/sysfs-platform-wilcoec
+++ b/Documentation/ABI/testing/sysfs-platform-wilcoec
@@ -24,3 +24,24 @@ Description:
off and remain off even if activated from the off state.
External monitors connected to the system are not affected.
In addition Wireless devices are turned off.
+
+What: /sys/bus/platform/devices/GOOG000C\:00/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...
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/legacy.c b/drivers/platform/chrome/wilco_ec/legacy.c
index 1fdf94d22f57..79bac5dccb39 100644
--- a/drivers/platform/chrome/wilco_ec/legacy.c
+++ b/drivers/platform/chrome/wilco_ec/legacy.c
@@ -11,6 +11,105 @@

#include "legacy.h"

+#ifdef CONFIG_WILCO_EC_SYSFS_RAW
+
+/* Raw data buffer, large enough to hold extended responses */
+static size_t raw_response_size;
+static u8 raw_response_data[EC_MAILBOX_DATA_SIZE_EXTENDED];
+
+ssize_t wilco_ec_raw_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct wilco_ec_device *ec = dev_get_drvdata(dev);
+ struct wilco_ec_message msg;
+ u8 raw_request_data[EC_MAILBOX_DATA_SIZE];
+ int in_offset = 0;
+ int out_offset = 0;
+ int ret;
+
+ while (in_offset < count) {
+ char word_buf[EC_MAILBOX_DATA_SIZE];
+ u8 byte;
+ int start_offset = in_offset;
+ int end_offset;
+
+ /* Find the start of the byte */
+ while (buf[start_offset] && isspace(buf[start_offset]))
+ start_offset++;
+ if (!buf[start_offset])
+ break;
+
+ /* Find the start of the next byte, if any */
+ end_offset = start_offset;
+ while (buf[end_offset] && !isspace(buf[end_offset]))
+ end_offset++;
+ if (start_offset > count || end_offset > count)
+ break;
+ if (start_offset > EC_MAILBOX_DATA_SIZE ||
+ end_offset > EC_MAILBOX_DATA_SIZE)
+ break;
+
+ /* Copy to a new NULL terminated string */
+ memcpy(word_buf, buf + start_offset, end_offset - start_offset);
+ word_buf[end_offset - start_offset] = '\0';
+
+ /* Convert from hex string */
+ ret = kstrtou8(word_buf, 16, &byte);
+ if (ret)
+ break;
+
+ /* Fill this byte into the request buffer */
+ raw_request_data[out_offset++] = byte;
+ if (out_offset >= EC_MAILBOX_DATA_SIZE)
+ break;
+
+ in_offset = end_offset;
+ }
+ if (out_offset == 0)
+ return -EINVAL;
+
+ /* Clear response data buffer */
+ memset(raw_response_data, '\0', EC_MAILBOX_DATA_SIZE_EXTENDED);
+
+ msg.type = raw_request_data[0] << 8 | raw_request_data[1];
+ msg.flags = WILCO_EC_FLAG_RAW;
+ msg.command = raw_request_data[2];
+ msg.request_data = raw_request_data + 3;
+ msg.request_size = out_offset - 3;
+ msg.response_data = raw_response_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(ec, &msg);
+ if (ret < 0)
+ return ret;
+ raw_response_size = ret;
+ return count;
+}
+
+ssize_t wilco_ec_raw_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ ssize_t count = 0;
+
+ if (raw_response_size) {
+ count = hex_dump_to_buffer(raw_response_data, raw_response_size,
+ 16, 1, buf, PAGE_SIZE, true);
+
+ /* Only return response the first time it is read */
+ raw_response_size = 0;
+ }
+
+ return count;
+}
+
+#endif /* CONFIG_WILCO_EC_SYSFS_RAW */
+
struct ec_info {
u8 index;
const char *label;
diff --git a/drivers/platform/chrome/wilco_ec/legacy.h b/drivers/platform/chrome/wilco_ec/legacy.h
index 5c857cb57fa9..340787d25d44 100644
--- a/drivers/platform/chrome/wilco_ec/legacy.h
+++ b/drivers/platform/chrome/wilco_ec/legacy.h
@@ -14,6 +14,52 @@
#define EC_INFO_SIZE 9
#define EC_COMMAND_STEALTH_MODE 0xfc

+#ifdef CONFIG_WILCO_EC_SYSFS_RAW
+
+/**
+ * wilco_ec_raw_store() - Write a raw command to EC, store result to view later
+ * @dev: Device representing the EC
+ * @attr: The attribute in question
+ * @buf: Input buffer, format explained below
+ * @count: Number of bytes in input buffer
+ *
+ * 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: read the EC info type 3 (EC firmware build date):
+ * # echo 00 f0 38 00 03 00 > raw
+ *
+ * After calling this function, read the result by using raw_show()
+ *
+ * Return: Number of bytes consumed from input, negative error code on failure
+ */
+ssize_t wilco_ec_raw_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t 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
+ */
+ssize_t wilco_ec_raw_show(struct device *dev, struct device_attribute *attr,
+ char *buf);
+
+#endif /* CONFIG_WILCO_EC_SYSFS_RAW */
+
/**
* wilco_ec_version_show() - Display Wilco Embedded Controller version info
*
diff --git a/drivers/platform/chrome/wilco_ec/sysfs.c b/drivers/platform/chrome/wilco_ec/sysfs.c
index e78a3ec3506b..0611a73fcdce 100644
--- a/drivers/platform/chrome/wilco_ec/sysfs.c
+++ b/drivers/platform/chrome/wilco_ec/sysfs.c
@@ -28,9 +28,15 @@ __ATTR(_name, 0644, wilco_ec_##_name##_show, wilco_ec_##_name##_store)
/* Make top-level attributes, which will live inside GOOG000C:00/ */
static struct device_attribute version_attr = WILCO_EC_ATTR_RO(version);
static struct device_attribute stealth_attr = WILCO_EC_ATTR_WO(stealth_mode);
+#ifdef CONFIG_WILCO_EC_SYSFS_RAW
+static struct device_attribute raw_attr = WILCO_EC_ATTR_RW(raw);
+#endif
static struct attribute *wilco_ec_toplevel_attrs[] = {
&version_attr.attr,
&stealth_attr.attr,
+#ifdef CONFIG_WILCO_EC_SYSFS_RAW
+ &raw_attr.attr,
+#endif
NULL
};
ATTRIBUTE_GROUPS(wilco_ec_toplevel);
--
2.20.1.97.g81188d93c3-goog
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