[PATCH v2 4/9] platform/chrome: Add support for raw commands in sysfs

[Nick Crews]

From: Duncan Laurie <dlaurie@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Nick Crews <ncrews@xxxxxxxxxx>
---

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