[PATCH 1/3] platform/chrome: wilco_ec: Split core and mailbox into separate modules

[PATCH 1/3] platform/chrome: wilco_ec: Split core and mailbox into separate modules

[Nick Crews]

It was bad design to lump the mailbox interface to the Wilco EC into the
same module as the code module, which loads all the subdrivers:
- This required the sub-drivers to depend on the core, which doesn't
really make sense, they should just depend on the mailbox interface.
- It caused problems with circular dependencies: An upcoming keyboard
backlight driver depends on the mailbox interface, which in the old
architecture makes it also depend on the core driver. However, the core
driver should be able to detect whether or not the keyboard
backlight is available, so the core module depends on the backlight
driver. This created a circular dependency.

By splitting up the mailbox interface and core driver into separate
modules, it fixes both of these problems.

Signed-off-by: Nick Crews <ncrews@chromium.org>
---
 drivers/platform/chrome/wilco_ec/Makefile  | 6 ++++--
 drivers/platform/chrome/wilco_ec/core.c    | 2 +-
 drivers/platform/chrome/wilco_ec/mailbox.c | 6 ++++++
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
index 063e7fb4ea17..9706aeb20ccb 100644
--- a/drivers/platform/chrome/wilco_ec/Makefile
+++ b/drivers/platform/chrome/wilco_ec/Makefile
@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
-wilco_ec-objs				:= core.o mailbox.o
-obj-$(CONFIG_WILCO_EC)			+= wilco_ec.o
+wilco_ec_mailbox-objs			:= mailbox.o
+obj-$(CONFIG_WILCO_EC)			+= wilco_ec_mailbox.o
+wilco_ec_core-objs			:= core.o
+obj-$(CONFIG_WILCO_EC)			+= wilco_ec_core.o
 wilco_ec_debugfs-objs			:= debugfs.o
 obj-$(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 05e1e2be1c91..ece30874f35f 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -20,7 +20,7 @@
 
 #include "../cros_ec_lpc_mec.h"
 
-#define DRV_NAME "wilco-ec"
+#define DRV_NAME "wilco-ec-core"
 
 static struct resource *wilco_get_resource(struct platform_device *pdev,
 					   int index)
diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c
index 14355668ddfa..ca6b92ce7e6d 100644
--- a/drivers/platform/chrome/wilco_ec/mailbox.c
+++ b/drivers/platform/chrome/wilco_ec/mailbox.c
@@ -18,6 +18,7 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/io.h>
+#include <linux/module.h>
 #include <linux/platform_data/wilco-ec.h>
 #include <linux/platform_device.h>
 
@@ -235,3 +236,8 @@ int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg)
 
 }
 EXPORT_SYMBOL_GPL(wilco_ec_mailbox);
+
+MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ChromeOS Wilco Embedded Controller mailbox interface");
+MODULE_ALIAS("platform:wilco-ec-mailbox");
-- 
2.20.1

[PATCH 2/3] platform/chrome: wilco_ec: Standardize mailbox interface

[Nick Crews]

The current API for the wilco EC mailbox interface is bad.

It assumes that most messages sent to the EC follow a similar structure,
with a command byte in MBOX[0], followed by a junk byte, followed by
actual data. This doesn't happen in several cases, such as setting the
RTC time, using the raw debugfs interface, and reading or writing
properties such as the Peak Shift policy (this last to be submitted soon).

Similarly for the response message from the EC, the current interface
assumes that the first byte of data is always 0, and the second byte
is unused. However, in both setting and getting the RTC time, in the
debugfs interface, and for reading and writing properties, this isn't
true.

The current way to resolve this is to use WILCO_EC_FLAG_RAW* flags to
specify when and when not to skip these initial bytes in the sent and
received message. They are confusing and used so much that they are
normal, and not exceptions. In addition, the first byte of
response in the debugfs interface is still always skipped, which is
weird, since this raw interface should be giving the entire result.

Additionally, sent messages assume the first byte is a command, and so
struct wilco_ec_message contains the "command" field. In setting or
getting properties however, the first byte is not a command, and so this
field has to be filled with a byte that isn't actually a command. This
is again inconsistent.

wilco_ec_message contains a result field as well, copied from
wilco_ec_response->result. The message result field should be removed:
if the message fails, the cause is already logged, and the callers are
alerted. They will never care about the actual state of the result flag.

These flags and different cases make the wilco_ec_transfer() function,
used in wilco_ec_mailbox(), really gross, dealing with a bunch of
different cases. It's difficult to figure out what it is doing.

Finally, making these assumptions about the structure of a message make
it so that the messages do not correspond well with the specification
for the EC's mailbox interface. For instance, this interface
specification may say that MBOX[9] in the received message contains
some information, but the calling code needs to remember that the first
byte of response is always skipped, and because it didn't set the
RESPONSE_RAW flag, the next byte is also skipped, so this information
is actually contained within wilco_ec_message->response_data[7]. This
makes it difficult to maintain this code in the future.

To fix these problems this patch standardizes the mailbox interface by:
- Removing the WILCO_EC_FLAG_RAW* flags
- Removing the command and reserved_raw bytes from wilco_ec_request
- Removing the mbox0 byte from wilco_ec_response
- Simplifying wilco_ec_transfer() because of these changes
- Gives the callers of wilco_ec_mailbox() the responsibility of exactly
  and consistently defining the structure of the mailbox request and
  response
- Removing command and result from wilco_ec_message.

This results in the reduction of total code, and makes it much more
maintainable and understandable.

Signed-off-by: Nick Crews <ncrews@chromium.org>
---
 drivers/platform/chrome/wilco_ec/debugfs.c | 43 ++++++++-------
 drivers/platform/chrome/wilco_ec/mailbox.c | 53 ++++++++----------
 drivers/rtc/rtc-wilco-ec.c                 | 63 +++++++++++++---------
 include/linux/platform_data/wilco-ec.h     | 22 +-------
 4 files changed, 83 insertions(+), 98 deletions(-)

diff --git a/drivers/platform/chrome/wilco_ec/debugfs.c b/drivers/platform/chrome/wilco_ec/debugfs.c
index c090db2cd5be..17c4c9068aaf 100644
--- a/drivers/platform/chrome/wilco_ec/debugfs.c
+++ b/drivers/platform/chrome/wilco_ec/debugfs.c
@@ -10,25 +10,26 @@
  * 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
+ * Bytes 0-1 indicate the message type, one of enum wilco_ec_msg_type
+ * Byte 2+ consist of the data passed in the request, starting at MBOX[0]
  *
- * 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.
+ * At least three bytes are required for writing, two for the type and at
+ * least a single byte of data. Only the first EC_MAILBOX_DATA_SIZE bytes
+ * of MBOX will be used.
  *
  * Example:
  * // Request EC info type 3 (EC firmware build date)
- * $ echo 00 f0 38 00 03 00 > raw
+ * // Corresponds with sending type 0x00f0 with MBOX = [38, 00, 03, 00]
+ * $ echo 00 f0 38 00 03 00 > /sys/kernel/debug/wilco_ec/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...
+ * // Corresponds with MBOX = [00, 00, 31, 32, 2f, 32, 31, ...]
+ * $ cat /sys/kernel/debug/wilco_ec/raw
+ * 00 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00  ..12/21/18.8...
+ *
+ * Note that the first 32 bytes of the received MBOX[] will be printed,
+ * even if some of the data is junk. It is up to you to know how many of
+ * the first bytes of data are the actual response.
  */
 
 #include <linux/ctype.h>
@@ -136,18 +137,15 @@ static ssize_t raw_write(struct file *file, const char __user *user_buf,
 	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 */
+	/* Need at least two bytes for message type and one byte of data */
 	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.flags = 0;
+	msg.request_data = request_data + 2;
+	msg.request_size = ret - 2;
+	memset(debug_info->raw_data, 0, sizeof(debug_info->raw_data));
 	msg.response_data = debug_info->raw_data;
 	msg.response_size = EC_MAILBOX_DATA_SIZE;
 
@@ -174,7 +172,8 @@ static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count,
 		fmt_len = hex_dump_to_buffer(debug_info->raw_data,
 					     debug_info->response_size,
 					     16, 1, debug_info->formatted_data,
-					     FORMATTED_BUFFER_SIZE, true);
+					     sizeof(debug_info->formatted_data),
+					     true);
 		/* Only return response the first time it is read */
 		debug_info->response_size = 0;
 	}
diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c
index ca6b92ce7e6d..0ea7291973c7 100644
--- a/drivers/platform/chrome/wilco_ec/mailbox.c
+++ b/drivers/platform/chrome/wilco_ec/mailbox.c
@@ -93,21 +93,10 @@ static void wilco_ec_prepare(struct wilco_ec_message *msg,
 			     struct wilco_ec_request *rq)
 {
 	memset(rq, 0, sizeof(*rq));
-
-	/* Handle messages without trimming bytes from the request */
-	if (msg->request_size && msg->flags & WILCO_EC_FLAG_RAW_REQUEST) {
-		rq->reserved_raw = *(u8 *)msg->request_data;
-		msg->request_size--;
-		memmove(msg->request_data, msg->request_data + 1,
-			msg->request_size);
-	}
-
-	/* Fill in request packet */
 	rq->struct_version = EC_MAILBOX_PROTO_VERSION;
 	rq->mailbox_id = msg->type;
 	rq->mailbox_version = EC_MAILBOX_VERSION;
-	rq->data_size = msg->request_size + EC_MAILBOX_DATA_EXTRA;
-	rq->command = msg->command;
+	rq->data_size = msg->request_size;
 
 	/* Checksum header and data */
 	rq->checksum = wilco_ec_checksum(rq, sizeof(*rq));
@@ -160,6 +149,12 @@ static int wilco_ec_transfer(struct wilco_ec_device *ec,
 		return -EIO;
 	}
 
+	/*
+	 * The EC always returns either EC_MAILBOX_DATA_SIZE or
+	 * EC_MAILBOX_DATA_SIZE_EXTENDED bytes of data, so we need to
+	 * calculate the checksum on **all** of this data, even if we
+	 * won't use all of it.
+	 */
 	if (msg->flags & WILCO_EC_FLAG_EXTENDED_DATA)
 		size = EC_MAILBOX_DATA_SIZE_EXTENDED;
 	else
@@ -174,33 +169,26 @@ static int wilco_ec_transfer(struct wilco_ec_device *ec,
 		return -EBADMSG;
 	}
 
-	/* Check that the EC reported success */
-	msg->result = rs->result;
-	if (msg->result) {
-		dev_dbg(ec->dev, "bad response: 0x%02x\n", msg->result);
+	if (rs->result) {
+		dev_dbg(ec->dev, "EC reported failure: 0x%02x\n", rs->result);
 		return -EBADMSG;
 	}
 
-	/* Check the returned data size, skipping the header */
 	if (rs->data_size != size) {
 		dev_dbg(ec->dev, "unexpected packet size (%u != %zu)",
 			rs->data_size, size);
 		return -EMSGSIZE;
 	}
 
-	/* Skip 1 response data byte unless specified */
-	size = (msg->flags & WILCO_EC_FLAG_RAW_RESPONSE) ? 0 : 1;
-	if ((ssize_t) rs->data_size - size < msg->response_size) {
-		dev_dbg(ec->dev, "response data too short (%zd < %zu)",
-			(ssize_t) rs->data_size - size, msg->response_size);
+	if (rs->data_size < msg->response_size) {
+		dev_dbg(ec->dev, "EC didn't return enough data (%u < %zu)",
+			rs->data_size, msg->response_size);
 		return -EMSGSIZE;
 	}
 
-	/* Ignore response data bytes as requested */
-	memcpy(msg->response_data, rs->data + size, msg->response_size);
+	memcpy(msg->response_data, rs->data, msg->response_size);
 
-	/* Return actual amount of data received */
-	return msg->response_size;
+	return rs->data_size;
 }
 
 /**
@@ -208,10 +196,12 @@ static int wilco_ec_transfer(struct wilco_ec_device *ec,
  * @ec: EC device.
  * @msg: EC message data for request and response.
  *
- * On entry msg->type, msg->flags, msg->command, msg->request_size,
- * msg->response_size, and msg->request_data should all be filled in.
+ * On entry msg->type, msg->request_size, and msg->request_data should all be
+ * filled in. If desired, msg->flags can be set.
  *
- * On exit msg->result and msg->response_data will be filled.
+ * If a response is expected, msg->response_size should be set, and
+ * msg->response_data should point to a buffer with enough space. On exit
+ * msg->response_data will be filled.
  *
  * Return: number of bytes received or negative error code on failure.
  */
@@ -220,9 +210,8 @@ int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg)
 	struct wilco_ec_request *rq;
 	int ret;
 
-	dev_dbg(ec->dev, "cmd=%02x type=%04x flags=%02x rslen=%zu rqlen=%zu\n",
-		msg->command, msg->type, msg->flags, msg->response_size,
-		msg->request_size);
+	dev_dbg(ec->dev, "type=%04x flags=%02x rslen=%zu rqlen=%zu\n",
+		msg->type, msg->flags, msg->response_size, msg->request_size);
 
 	mutex_lock(&ec->mailbox_lock);
 	/* Prepare request packet */
diff --git a/drivers/rtc/rtc-wilco-ec.c b/drivers/rtc/rtc-wilco-ec.c
index e62bda0cb53e..8ad4c4e6d557 100644
--- a/drivers/rtc/rtc-wilco-ec.c
+++ b/drivers/rtc/rtc-wilco-ec.c
@@ -21,8 +21,20 @@
 #define EC_CMOS_TOD_WRITE		0x02
 #define EC_CMOS_TOD_READ		0x08
 
+/* Message sent to the EC to request the current time. */
+struct ec_rtc_read_request {
+	u8 command;
+	u8 reserved;
+	u8 param;
+} __packed;
+static struct ec_rtc_read_request read_rq = {
+	.command = EC_COMMAND_CMOS,
+	.param = EC_CMOS_TOD_READ,
+};
+
 /**
- * struct ec_rtc_read - Format of RTC returned by EC.
+ * struct ec_rtc_read_response - Format of RTC returned by EC.
+ * @reserved: Unused byte
  * @second: Second value (0..59)
  * @minute: Minute value (0..59)
  * @hour: Hour value (0..23)
@@ -33,7 +45,8 @@
  *
  * All values are presented in binary (not BCD).
  */
-struct ec_rtc_read {
+struct ec_rtc_read_response {
+	u8 reserved;
 	u8 second;
 	u8 minute;
 	u8 hour;
@@ -44,8 +57,10 @@ struct ec_rtc_read {
 } __packed;
 
 /**
- * struct ec_rtc_write - Format of RTC sent to the EC.
- * @param: EC_CMOS_TOD_WRITE
+ * struct ec_rtc_write_request - Format of RTC sent to the EC.
+ * @command: Always EC_COMMAND_CMOS
+ * @reserved: Unused byte
+ * @param: Always EC_CMOS_TOD_WRITE
  * @century: Century value (full year / 100)
  * @year: Year value (full year % 100)
  * @month: Month value (1..12)
@@ -57,7 +72,9 @@ struct ec_rtc_read {
  *
  * All values are presented in BCD.
  */
-struct ec_rtc_write {
+struct ec_rtc_write_request {
+	u8 command;
+	u8 reserved;
 	u8 param;
 	u8 century;
 	u8 year;
@@ -72,19 +89,17 @@ struct ec_rtc_write {
 static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm)
 {
 	struct wilco_ec_device *ec = dev_get_drvdata(dev->parent);
-	u8 param = EC_CMOS_TOD_READ;
-	struct ec_rtc_read rtc;
-	struct wilco_ec_message msg = {
-		.type = WILCO_EC_MSG_LEGACY,
-		.flags = WILCO_EC_FLAG_RAW_RESPONSE,
-		.command = EC_COMMAND_CMOS,
-		.request_data = &param,
-		.request_size = sizeof(param),
-		.response_data = &rtc,
-		.response_size = sizeof(rtc),
-	};
+	struct ec_rtc_read_response rtc;
+	struct wilco_ec_message msg;
 	int ret;
 
+	memset(&msg, 0, sizeof(msg));
+	msg.type = WILCO_EC_MSG_LEGACY;
+	msg.request_data = &read_rq;
+	msg.request_size = sizeof(read_rq);
+	msg.response_data = &rtc;
+	msg.response_size = sizeof(rtc);
+
 	ret = wilco_ec_mailbox(ec, &msg);
 	if (ret < 0)
 		return ret;
@@ -106,14 +121,8 @@ static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm)
 static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)
 {
 	struct wilco_ec_device *ec = dev_get_drvdata(dev->parent);
-	struct ec_rtc_write rtc;
-	struct wilco_ec_message msg = {
-		.type = WILCO_EC_MSG_LEGACY,
-		.flags = WILCO_EC_FLAG_RAW_RESPONSE,
-		.command = EC_COMMAND_CMOS,
-		.request_data = &rtc,
-		.request_size = sizeof(rtc),
-	};
+	struct ec_rtc_write_request rtc;
+	struct wilco_ec_message msg;
 	int year = tm->tm_year + 1900;
 	/*
 	 * Convert from 0=Sunday to 0=Saturday for the EC
@@ -123,6 +132,7 @@ static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)
 	int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1;
 	int ret;
 
+	rtc.command	= EC_COMMAND_CMOS;
 	rtc.param	= EC_CMOS_TOD_WRITE;
 	rtc.century	= bin2bcd(year / 100);
 	rtc.year	= bin2bcd(year % 100);
@@ -133,6 +143,11 @@ static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)
 	rtc.second	= bin2bcd(tm->tm_sec);
 	rtc.weekday	= bin2bcd(wday);
 
+	memset(&msg, 0, sizeof(msg));
+	msg.type = WILCO_EC_MSG_LEGACY;
+	msg.request_data = &rtc;
+	msg.request_size = sizeof(rtc);
+
 	ret = wilco_ec_mailbox(ec, &msg);
 	if (ret < 0)
 		return ret;
diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
index 446473a46b88..1ff224793c99 100644
--- a/include/linux/platform_data/wilco-ec.h
+++ b/include/linux/platform_data/wilco-ec.h
@@ -14,10 +14,6 @@
 /* Message flags for using the mailbox() interface */
 #define WILCO_EC_FLAG_NO_RESPONSE	BIT(0) /* EC does not respond */
 #define WILCO_EC_FLAG_EXTENDED_DATA	BIT(1) /* EC returns 256 data bytes */
-#define WILCO_EC_FLAG_RAW_REQUEST	BIT(2) /* Do not trim request data */
-#define WILCO_EC_FLAG_RAW_RESPONSE	BIT(3) /* Do not trim response data */
-#define WILCO_EC_FLAG_RAW		(WILCO_EC_FLAG_RAW_REQUEST | \
-					 WILCO_EC_FLAG_RAW_RESPONSE)
 
 /* Normal commands have a maximum 32 bytes of data */
 #define EC_MAILBOX_DATA_SIZE		32
@@ -56,10 +52,7 @@ struct wilco_ec_device {
  * @mailbox_id: Mailbox identifier, specifies the command set.
  * @mailbox_version: Mailbox interface version %EC_MAILBOX_VERSION
  * @reserved: Set to zero.
- * @data_size: Length of request, data + last 2 bytes of the header.
- * @command: Mailbox command code, unique for each mailbox_id set.
- * @reserved_raw: Set to zero for most commands, but is used by
- *                some command types and for raw commands.
+ * @data_size: Length of following data.
  */
 struct wilco_ec_request {
 	u8 struct_version;
@@ -68,8 +61,6 @@ struct wilco_ec_request {
 	u8 mailbox_version;
 	u8 reserved;
 	u16 data_size;
-	u8 command;
-	u8 reserved_raw;
 } __packed;
 
 /**
@@ -79,8 +70,6 @@ struct wilco_ec_request {
  * @result: Result code from the EC.  Non-zero indicates an error.
  * @data_size: Length of the response data buffer.
  * @reserved: Set to zero.
- * @mbox0: EC returned data at offset 0 is unused (always 0) so this byte
- *         is treated as part of the header instead of the data.
  * @data: Response data buffer.  Max size is %EC_MAILBOX_DATA_SIZE_EXTENDED.
  */
 struct wilco_ec_response {
@@ -89,7 +78,6 @@ struct wilco_ec_response {
 	u16 result;
 	u16 data_size;
 	u8 reserved[2];
-	u8 mbox0;
 	u8 data[0];
 } __packed;
 
@@ -111,21 +99,15 @@ enum wilco_ec_msg_type {
  * struct wilco_ec_message - Request and response message.
  * @type: Mailbox message type.
  * @flags: Message flags, e.g. %WILCO_EC_FLAG_NO_RESPONSE.
- * @command: Mailbox command code.
- * @result: Result code from the EC.  Non-zero indicates an error.
  * @request_size: Number of bytes to send to the EC.
  * @request_data: Buffer containing the request data.
- * @response_size: Number of bytes expected from the EC.
- *                 This is 32 by default and 256 if the flag
- *                 is set for %WILCO_EC_FLAG_EXTENDED_DATA
+ * @response_size: Number of bytes to read from EC.
  * @response_data: Buffer containing the response data, should be
  *                 response_size bytes and allocated by caller.
  */
 struct wilco_ec_message {
 	enum wilco_ec_msg_type type;
 	u8 flags;
-	u8 command;
-	u8 result;
 	size_t request_size;
 	void *request_data;
 	size_t response_size;
-- 
2.20.1

[PATCH 3/3] platform/chrome: Add Wilco EC keyboard backlight LEDs support

[Nick Crews]

The EC is in charge of controlling the keyboard backlight on
the Wilco platform. We expose a standard LED class device at
/sys/class/leds/wilco::kbd_backlight. This driver is modeled
after the standard Chrome OS keyboard backlight driver at
drivers/platform/chrome/cros_kbd_led_backlight.c

Some Wilco devices do not support a keyboard backlight. This
is checked via wilco_ec_keyboard_leds_exist() in the core driver,
and a platform_device will only be registered by the core if
a backlight is supported.

After an EC reset the backlight could be in a non-PWM mode.
Earlier in the boot sequence the BIOS should send a command to
the EC to set the brightness, so things **should** be set up,
but we double check in probe() as we query the initial brightness.
If not set up, then set the brightness to KBBL_DEFAULT_BRIGHTNESS.

Since the EC will never change the backlight level of its own accord,
we don't need to implement a brightness_get() method.

v2 changes:
-Remove and fix uses of led vs LED in kconfig
-Assume BIOS initializes brightness, but double check in probe()
-Remove get_brightness() callback, as EC never changes brightness
 by itself.
-Use a __packed struct as message instead of opaque array
-Add exported wilco_ec_keyboard_leds_exist() so the core driver
 now only creates a platform _device if relevant
-Fix use of keyboard_led_set_brightness() since it can sleep

Signed-off-by: Nick Crews <ncrews@chromium.org>
---
 drivers/platform/chrome/wilco_ec/Kconfig      |   9 +
 drivers/platform/chrome/wilco_ec/Makefile     |   2 +
 drivers/platform/chrome/wilco_ec/core.c       |  16 ++
 .../chrome/wilco_ec/kbd_led_backlight.c       | 216 ++++++++++++++++++
 include/linux/platform_data/wilco-ec.h        |  10 +
 5 files changed, 253 insertions(+)
 create mode 100644 drivers/platform/chrome/wilco_ec/kbd_led_backlight.c

diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig
index e09e4cebe9b4..82abd3377a67 100644
--- a/drivers/platform/chrome/wilco_ec/Kconfig
+++ b/drivers/platform/chrome/wilco_ec/Kconfig
@@ -18,3 +18,12 @@ config WILCO_EC_DEBUGFS
 	  manipulation and allow for testing arbitrary commands.  This
 	  interface is intended for debug only and will not be present
 	  on production devices.
+
+config WILCO_EC_KBD_BACKLIGHT
+	tristate "Enable keyboard backlight control"
+	depends on WILCO_EC
+	help
+	  If you say Y here, you get support to set the keyboard backlight
+	  brightness. This happens via a standard LED driver that uses the
+	  Wilco EC mailbox interface. A standard LED class device will
+	  appear under /sys/class/leds/wilco::kbd_backlight
diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
index 9706aeb20ccb..114940aa9d53 100644
--- a/drivers/platform/chrome/wilco_ec/Makefile
+++ b/drivers/platform/chrome/wilco_ec/Makefile
@@ -6,3 +6,5 @@ wilco_ec_core-objs			:= core.o
 obj-$(CONFIG_WILCO_EC)			+= wilco_ec_core.o
 wilco_ec_debugfs-objs			:= debugfs.o
 obj-$(CONFIG_WILCO_EC_DEBUGFS)		+= wilco_ec_debugfs.o
+wilco_kbd_backlight-objs		:= kbd_led_backlight.o
+obj-$(CONFIG_WILCO_EC_KBD_BACKLIGHT)	+= wilco_kbd_backlight.o
diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
index ece30874f35f..c62990e4fa02 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -89,8 +89,23 @@ static int wilco_ec_probe(struct platform_device *pdev)
 		goto unregister_debugfs;
 	}
 
+	/* Register child dev to be found by the keyboard backlight driver. */
+	if (wilco_ec_keyboard_leds_exist(ec)) {
+		ec->kbbl_pdev = platform_device_register_data(dev,
+						"wilco-kbd-backlight",
+						PLATFORM_DEVID_AUTO, NULL, 0);
+		if (IS_ERR(ec->kbbl_pdev)) {
+			dev_err(dev,
+				"Failed to create keyboard backlight pdev\n");
+			ret = PTR_ERR(ec->kbbl_pdev);
+			goto unregister_rtc;
+		}
+	}
+
 	return 0;
 
+unregister_rtc:
+	platform_device_unregister(ec->rtc_pdev);
 unregister_debugfs:
 	if (ec->debugfs_pdev)
 		platform_device_unregister(ec->debugfs_pdev);
@@ -102,6 +117,7 @@ static int wilco_ec_remove(struct platform_device *pdev)
 {
 	struct wilco_ec_device *ec = platform_get_drvdata(pdev);
 
+	platform_device_unregister(ec->kbbl_pdev);
 	platform_device_unregister(ec->rtc_pdev);
 	if (ec->debugfs_pdev)
 		platform_device_unregister(ec->debugfs_pdev);
diff --git a/drivers/platform/chrome/wilco_ec/kbd_led_backlight.c b/drivers/platform/chrome/wilco_ec/kbd_led_backlight.c
new file mode 100644
index 000000000000..14cbc54cd8db
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/kbd_led_backlight.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Keyboard backlight LED driver for the Wilco Embedded Controller
+ *
+ * Copyright 2019 Google LLC
+ *
+ * The EC is in charge of controlling the keyboard backlight on
+ * the Wilco platform. We expose a standard LED class device at
+ * /sys/class/leds/wilco::kbd_backlight. Power Manager normally
+ * controls the backlight by writing a percentage in range [0, 100]
+ * to the brightness property. This driver is modeled after the
+ * standard Chrome OS keyboard backlight driver at
+ * drivers/platform/chrome/cros_kbd_led_backlight.c
+ *
+ * Some Wilco devices do not support a keyboard backlight. This
+ * is checked via wilco_ec_keyboard_leds_exist() in the core driver,
+ * and a platform_device will only be registered by the core if
+ * a backlight is supported.
+ *
+ * After an EC reset the backlight could be in a non-PWM mode.
+ * Earlier in the boot sequence the BIOS should send a command to
+ * the EC to set the brightness, so things **should** be set up,
+ * but we double check in probe() as we query the initial brightness.
+ * If not set up, then we set the brightness to KBBL_DEFAULT_BRIGHTNESS.
+ *
+ * Since the EC will never change the backlight level of its own accord,
+ * we don't need to implement a brightness_get() method.
+ */
+
+#include <linux/leds.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_data/wilco-ec.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define DRV_NAME		"wilco-kbd-backlight"
+
+#define EC_COMMAND_KB_BKLIGHT	0x75
+#define KBBL_MODE_PWM		BIT(1)	/* Flag to set brightness by percent */
+/* What action do we want the EC to perform? */
+enum kbbl_subcommand {
+	KBBL_SUBCMD_GET_FEATURES = 0x00,
+	KBBL_SUBCMD_GET_STATE = 0x01,
+	KBBL_SUBCMD_SET_STATE = 0x02,
+};
+
+#define KBBL_DEFAULT_BRIGHTNESS	0
+
+/* The message sent to and received by the EC */
+struct wilco_ec_kbbl_msg {
+	u8 command;		/* Always EC_COMMAND_KB_BKLIGHT */
+	u8 status;		/* Will be set to 0xFF by EC on failure */
+	u8 subcmd;		/* One of enum kbbl_subcommand */
+	u8 reserved3;
+	u8 mode;		/* Always KBBL_MODE_PWM */
+	u8 reserved5to8[4];
+	u8 percent;
+	u8 reserved10to15[6];
+} __packed;
+
+struct wilco_keyboard_led_data {
+	struct wilco_ec_device *ec;
+	struct led_classdev keyboard;
+};
+
+/**
+ * wilco_ec_keyboard_leds_exist() - Is the keyboad backlight supported?
+ * @ec: EC device to query.
+ *
+ * Return: true if backlight is supported, false if not or if error occurred.
+ */
+bool wilco_ec_keyboard_leds_exist(struct wilco_ec_device *ec)
+{
+	struct wilco_ec_kbbl_msg request;
+	struct wilco_ec_kbbl_msg response;
+	struct wilco_ec_message msg;
+	int ret;
+
+	memset(&request, 0, sizeof(request));
+	request.command = EC_COMMAND_KB_BKLIGHT;
+	request.subcmd = KBBL_SUBCMD_GET_FEATURES;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.type = WILCO_EC_MSG_LEGACY;
+	msg.request_data = &request;
+	msg.request_size = sizeof(request);
+	msg.response_data = &response;
+	msg.response_size = sizeof(response);
+
+	ret = wilco_ec_mailbox(ec, &msg);
+	if (ret < 0) {
+		dev_err(ec->dev,
+			"Failed checking keyboard backlight support: %d", ret);
+		return false;
+	}
+
+	return response.status != 0xFF;
+}
+EXPORT_SYMBOL_GPL(wilco_ec_keyboard_leds_exist);
+
+/* This may sleep because it uses wilco_ec_mailbox() */
+static int keyboard_led_set_brightness(struct led_classdev *cdev,
+				       enum led_brightness brightness)
+{
+	struct wilco_ec_kbbl_msg request;
+	struct wilco_ec_message msg;
+	struct wilco_keyboard_led_data *data;
+	int ret;
+
+	memset(&request, 0, sizeof(request));
+	request.command = EC_COMMAND_KB_BKLIGHT;
+	request.subcmd = KBBL_SUBCMD_SET_STATE;
+	request.mode = KBBL_MODE_PWM;
+	request.percent = brightness;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.type = WILCO_EC_MSG_LEGACY;
+	msg.request_data = &request;
+	msg.request_size = sizeof(request);
+	msg.response_size = 0;
+
+	data = container_of(cdev, struct wilco_keyboard_led_data, keyboard);
+	ret = wilco_ec_mailbox(data->ec, &msg);
+	if (ret < 0)
+		dev_err(cdev->dev, "Failed setting brightness: %d", ret);
+
+	return 0;
+}
+
+/*
+ * Get the current brightness, ensuring that we are in PWM mode. If not
+ * in PWM mode, then the current brightness is meaningless, so set the
+ * brightness to KBBL_DEFAULT_BRIGHTNESS.
+ *
+ * Return: Final brightness of the keyboard, or negative error code on failure.
+ */
+static int initialize_brightness(struct wilco_keyboard_led_data *data)
+{
+	struct wilco_ec_kbbl_msg request;
+	struct wilco_ec_kbbl_msg response;
+	struct wilco_ec_message msg;
+	int ret;
+
+	memset(&request, 0, sizeof(request));
+	request.command = EC_COMMAND_KB_BKLIGHT;
+	request.subcmd = KBBL_SUBCMD_GET_STATE;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.type = WILCO_EC_MSG_LEGACY;
+	msg.request_data = &request;
+	msg.request_size = sizeof(request);
+	msg.response_data = &response;
+	msg.response_size = sizeof(response);
+
+	ret = wilco_ec_mailbox(data->ec, &msg);
+	if (ret < 0) {
+		dev_err(data->ec->dev, "Failed getting brightness: %d", ret);
+		return ret;
+	}
+
+	if (response.mode & KBBL_MODE_PWM)
+		return response.percent;
+
+	ret = led_set_brightness_sync(&data->keyboard, KBBL_DEFAULT_BRIGHTNESS);
+	if (ret < 0)
+		return ret;
+
+	return KBBL_DEFAULT_BRIGHTNESS;
+}
+
+static int keyboard_led_probe(struct platform_device *pdev)
+{
+	struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+	struct wilco_keyboard_led_data *data;
+	int ret;
+
+	if (!wilco_ec_keyboard_leds_exist(ec))
+		return -ENXIO;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->ec = ec;
+	/* To be found by Power Manager needs to end in ":kbd_backlight" */
+	data->keyboard.name = "wilco::kbd_backlight";
+	data->keyboard.max_brightness = 100;
+	data->keyboard.flags = LED_CORE_SUSPENDRESUME;
+	data->keyboard.brightness_set_blocking = keyboard_led_set_brightness;
+	ret = initialize_brightness(data);
+	if (ret < 0)
+		return ret;
+	data->keyboard.brightness = ret;
+
+	ret = devm_led_classdev_register(&pdev->dev, &data->keyboard);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static struct platform_driver keyboard_led_driver = {
+	.driver = {
+		.name = DRV_NAME,
+	},
+	.probe = keyboard_led_probe,
+};
+module_platform_driver(keyboard_led_driver);
+
+MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
+MODULE_DESCRIPTION("Wilco keyboard backlight LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
index 1ff224793c99..785aa50513c2 100644
--- a/include/linux/platform_data/wilco-ec.h
+++ b/include/linux/platform_data/wilco-ec.h
@@ -32,6 +32,7 @@
  * @data_size: Size of the data buffer used for EC communication.
  * @debugfs_pdev: The child platform_device used by the debugfs sub-driver.
  * @rtc_pdev: The child platform_device used by the RTC sub-driver.
+ * @kbbl_pdev: The child pdev used by the keyboard backlight sub-driver.
  */
 struct wilco_ec_device {
 	struct device *dev;
@@ -43,6 +44,7 @@ struct wilco_ec_device {
 	size_t data_size;
 	struct platform_device *debugfs_pdev;
 	struct platform_device *rtc_pdev;
+	struct platform_device *kbbl_pdev;
 };
 
 /**
@@ -114,6 +116,14 @@ struct wilco_ec_message {
 	void *response_data;
 };
 
+/**
+ * wilco_ec_keyboard_leds_exist() - Is the keyboad backlight supported?
+ * @ec: EC device to query.
+ *
+ * Return: true if backlight is supported, false if not or if error occurred.
+ */
+bool wilco_ec_keyboard_leds_exist(struct wilco_ec_device *ec);
+
 /**
  * wilco_ec_mailbox() - Send request to the EC and receive the response.
  * @ec: Wilco EC device.
-- 
2.20.1

Re: [PATCH 3/3] platform/chrome: Add Wilco EC keyboard backlight LEDs support

[Pavel Machek]

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Hi!

> The EC is in charge of controlling the keyboard backlight on
> the Wilco platform. We expose a standard LED class device at
> /sys/class/leds/wilco::kbd_backlight. This driver is modeled
> after the standard Chrome OS keyboard backlight driver at
> drivers/platform/chrome/cros_kbd_led_backlight.c

Please make it platform::kbd_backlight . Userland should not need to
know what wilco is...

What is wilco, anyway?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [PATCH 3/3] platform/chrome: Add Wilco EC keyboard backlight LEDs support

[Nick Crews]

On Fri, Mar 22, 2019 at 5:35 AM Pavel Machek <pavel@ucw.cz> wrote:
>
> Hi!
>
> > The EC is in charge of controlling the keyboard backlight on
> > the Wilco platform. We expose a standard LED class device at
> > /sys/class/leds/wilco::kbd_backlight. This driver is modeled
> > after the standard Chrome OS keyboard backlight driver at
> > drivers/platform/chrome/cros_kbd_led_backlight.c
>
> Please make it platform::kbd_backlight . Userland should not need to
> know what wilco is...

The corresponding device for normal chromeos devices is
"chromeos::kbd_backlight". I wanted to differentiate this device from
that one, so I thought that "wilco" a similar level of specific-ness as
"chromeos". Using "platform" seems too general. The power manager
daemon that controls the backlight just searches for LEDs ending with
"*:kbd_backlight" so it should work for that, and I figured any user just
browsing through sysfs would be able to guess what the LED does.

This is maybe a question for those who will need to maintain the
Chrome OS system after adding this? Could some more
Chrome OS-specific people chime in on this? I also CC'ed Simon
Que, the author of the original driver (Simon, we are talking about
https://lkml.org/lkml/2019/3/21/999)

>
> What is wilco, anyway?

Wilco is a new Chrome OS device which does not use the same embedded
controller as the rest of the Chrome OS ecosystem. Thus, we need this new
driver because the old one will not be compatible.

>
>                                                                         Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 1/3] platform/chrome: wilco_ec: Split core and mailbox into separate modules

[Enric Balletbo i Serra]

Hi Nick,

Thanks for the patch, some comments below.

On 21/3/19 23:13, Nick Crews wrote:
> It was bad design to lump the mailbox interface to the Wilco EC into the
> same module as the code module, which loads all the subdrivers:

Typo: s/code/core/?

> - This required the sub-drivers to depend on the core, which doesn't
> really make sense, they should just depend on the mailbox interface.
> - It caused problems with circular dependencies: An upcoming keyboard
> backlight driver depends on the mailbox interface, which in the old
> architecture makes it also depend on the core driver. However, the core
> driver should be able to detect whether or not the keyboard
> backlight is available, so the core module depends on the backlight
> driver. This created a circular dependency.
> 
> By splitting up the mailbox interface and core driver into separate
> modules, it fixes both of these problems.
> 
> Signed-off-by: Nick Crews <ncrews@chromium.org>
> ---
>  drivers/platform/chrome/wilco_ec/Makefile  | 6 ++++--
>  drivers/platform/chrome/wilco_ec/core.c    | 2 +-
>  drivers/platform/chrome/wilco_ec/mailbox.c | 6 ++++++
>  3 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
> index 063e7fb4ea17..9706aeb20ccb 100644
> --- a/drivers/platform/chrome/wilco_ec/Makefile
> +++ b/drivers/platform/chrome/wilco_ec/Makefile
> @@ -1,6 +1,8 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> -wilco_ec-objs				:= core.o mailbox.o
> -obj-$(CONFIG_WILCO_EC)			+= wilco_ec.o
> +wilco_ec_mailbox-objs			:= mailbox.o
> +obj-$(CONFIG_WILCO_EC)			+= wilco_ec_mailbox.o
> +wilco_ec_core-objs			:= core.o
> +obj-$(CONFIG_WILCO_EC)			+= wilco_ec_core.o

Odd, same config definition (CONFIG_WILCO_EC) for two different kernel modules?

>  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 05e1e2be1c91..ece30874f35f 100644
> --- a/drivers/platform/chrome/wilco_ec/core.c
> +++ b/drivers/platform/chrome/wilco_ec/core.c
> @@ -20,7 +20,7 @@
>  
>  #include "../cros_ec_lpc_mec.h"
>  
> -#define DRV_NAME "wilco-ec"
> +#define DRV_NAME "wilco-ec-core"
>  
>  static struct resource *wilco_get_resource(struct platform_device *pdev,
>  					   int index)
> diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c
> index 14355668ddfa..ca6b92ce7e6d 100644
> --- a/drivers/platform/chrome/wilco_ec/mailbox.c
> +++ b/drivers/platform/chrome/wilco_ec/mailbox.c
> @@ -18,6 +18,7 @@
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/io.h>
> +#include <linux/module.h>
>  #include <linux/platform_data/wilco-ec.h>
>  #include <linux/platform_device.h>
>  
> @@ -235,3 +236,8 @@ int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg)
>  
>  }
>  EXPORT_SYMBOL_GPL(wilco_ec_mailbox);
> +
> +MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("ChromeOS Wilco Embedded Controller mailbox interface");
> +MODULE_ALIAS("platform:wilco-ec-mailbox");
> 

Thanks,
- Enric

Re: [PATCH 1/3] platform/chrome: wilco_ec: Split core and mailbox into separate modules

[Nick Crews]

On Mon, Mar 25, 2019 at 11:18 AM Enric Balletbo i Serra
<enric.balletbo@collabora.com> wrote:
>
> Hi Nick,
>
> Thanks for the patch, some comments below.
>
> On 21/3/19 23:13, Nick Crews wrote:
> > It was bad design to lump the mailbox interface to the Wilco EC into the
> > same module as the code module, which loads all the subdrivers:
>
> Typo: s/code/core/?
>
> > - This required the sub-drivers to depend on the core, which doesn't
> > really make sense, they should just depend on the mailbox interface.
> > - It caused problems with circular dependencies: An upcoming keyboard
> > backlight driver depends on the mailbox interface, which in the old
> > architecture makes it also depend on the core driver. However, the core
> > driver should be able to detect whether or not the keyboard
> > backlight is available, so the core module depends on the backlight
> > driver. This created a circular dependency.
> >
> > By splitting up the mailbox interface and core driver into separate
> > modules, it fixes both of these problems.
> >
> > Signed-off-by: Nick Crews <ncrews@chromium.org>
> > ---
> >  drivers/platform/chrome/wilco_ec/Makefile  | 6 ++++--
> >  drivers/platform/chrome/wilco_ec/core.c    | 2 +-
> >  drivers/platform/chrome/wilco_ec/mailbox.c | 6 ++++++
> >  3 files changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
> > index 063e7fb4ea17..9706aeb20ccb 100644
> > --- a/drivers/platform/chrome/wilco_ec/Makefile
> > +++ b/drivers/platform/chrome/wilco_ec/Makefile
> > @@ -1,6 +1,8 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >
> > -wilco_ec-objs                                := core.o mailbox.o
> > -obj-$(CONFIG_WILCO_EC)                       += wilco_ec.o
> > +wilco_ec_mailbox-objs                        := mailbox.o
> > +obj-$(CONFIG_WILCO_EC)                       += wilco_ec_mailbox.o
> > +wilco_ec_core-objs                   := core.o
> > +obj-$(CONFIG_WILCO_EC)                       += wilco_ec_core.o
>
> Odd, same config definition (CONFIG_WILCO_EC) for two different kernel modules?

The mailbox and core modules will always be wanted together, so I
figured just keep it
as one config option. I think it would be confusing to add unnecessary
config options.
Is there a good alternative?

>
> >  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 05e1e2be1c91..ece30874f35f 100644
> > --- a/drivers/platform/chrome/wilco_ec/core.c
> > +++ b/drivers/platform/chrome/wilco_ec/core.c
> > @@ -20,7 +20,7 @@
> >
> >  #include "../cros_ec_lpc_mec.h"
> >
> > -#define DRV_NAME "wilco-ec"
> > +#define DRV_NAME "wilco-ec-core"
> >
> >  static struct resource *wilco_get_resource(struct platform_device *pdev,
> >                                          int index)
> > diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c
> > index 14355668ddfa..ca6b92ce7e6d 100644
> > --- a/drivers/platform/chrome/wilco_ec/mailbox.c
> > +++ b/drivers/platform/chrome/wilco_ec/mailbox.c
> > @@ -18,6 +18,7 @@
> >  #include <linux/delay.h>
> >  #include <linux/device.h>
> >  #include <linux/io.h>
> > +#include <linux/module.h>
> >  #include <linux/platform_data/wilco-ec.h>
> >  #include <linux/platform_device.h>
> >
> > @@ -235,3 +236,8 @@ int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg)
> >
> >  }
> >  EXPORT_SYMBOL_GPL(wilco_ec_mailbox);
> > +
> > +MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_DESCRIPTION("ChromeOS Wilco Embedded Controller mailbox interface");
> > +MODULE_ALIAS("platform:wilco-ec-mailbox");
> >
>
> Thanks,
> - Enric

Re: [PATCH 3/3] platform/chrome: Add Wilco EC keyboard backlight LEDs support

[Nick Crews]

On Fri, Mar 22, 2019 at 9:49 AM Nick Crews <ncrews@chromium.org> wrote:
>
> On Fri, Mar 22, 2019 at 5:35 AM Pavel Machek <pavel@ucw.cz> wrote:
> >
> > Hi!
> >
> > > The EC is in charge of controlling the keyboard backlight on
> > > the Wilco platform. We expose a standard LED class device at
> > > /sys/class/leds/wilco::kbd_backlight. This driver is modeled
> > > after the standard Chrome OS keyboard backlight driver at
> > > drivers/platform/chrome/cros_kbd_led_backlight.c
> >
> > Please make it platform::kbd_backlight . Userland should not need to
> > know what wilco is...
>
> The corresponding device for normal chromeos devices is
> "chromeos::kbd_backlight". I wanted to differentiate this device from
> that one, so I thought that "wilco" a similar level of specific-ness as
> "chromeos". Using "platform" seems too general. The power manager
> daemon that controls the backlight just searches for LEDs ending with
> "*:kbd_backlight" so it should work for that, and I figured any user just
> browsing through sysfs would be able to guess what the LED does.
>
> This is maybe a question for those who will need to maintain the
> Chrome OS system after adding this? Could some more
> Chrome OS-specific people chime in on this? I also CC'ed Simon
> Que, the author of the original driver (Simon, we are talking about
> https://lkml.org/lkml/2019/3/21/999)

From talking to Simon, since the interface is the same, I'll just keep the name
as "chromeos::kbd_backlight". This makes sense to me too. I'll send out a
patch fixing this.

>
> >
> > What is wilco, anyway?
>
> Wilco is a new Chrome OS device which does not use the same embedded
> controller as the rest of the Chrome OS ecosystem. Thus, we need this new
> driver because the old one will not be compatible.
>
> >
> >                                                                         Pavel
> > --
> > (english) http://www.livejournal.com/~pavelmachek
> > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 3/3] platform/chrome: Add Wilco EC keyboard backlight LEDs support

[Dmitry Torokhov]

On Fri, Mar 22, 2019 at 4:35 AM Pavel Machek <pavel@ucw.cz> wrote:
>
> Hi!
>
> > The EC is in charge of controlling the keyboard backlight on
> > the Wilco platform. We expose a standard LED class device at
> > /sys/class/leds/wilco::kbd_backlight. This driver is modeled
> > after the standard Chrome OS keyboard backlight driver at
> > drivers/platform/chrome/cros_kbd_led_backlight.c
>
> Please make it platform::kbd_backlight . Userland should not need to
> know what wilco is...

It should not. But the current convention is "<device>::kbd-backlight":

dtor@dtor-ws:~/kernel/work $ git grep "::kbd_backlight" -- drivers/
drivers/hid/hid-asus.c: drvdata->kbd_backlight->cdev.name =
"asus::kbd_backlight";
drivers/hid/hid-google-hammer.c:        kbd_backlight->cdev.name =
"hammer::kbd_backlight";
drivers/hwmon/applesmc.c:       .name                   = "smc::kbd_backlight",
drivers/input/misc/ims-pcu.c:            "pcu%d::kbd_backlight",
pcu->device_no);
drivers/platform/chrome/cros_kbd_led_backlight.c:       cdev->name =
"chromeos::kbd_backlight";
drivers/platform/x86/asus-laptop.c:             cdev->name =
"asus::kbd_backlight";
drivers/platform/x86/asus-wmi.c:                asus->kbd_led.name =
"asus::kbd_backlight";
drivers/platform/x86/dell-laptop.c:     .name           = "dell::kbd_backlight",
drivers/platform/x86/samsung-laptop.c:          samsung->kbd_led.name
= "samsung::kbd_backlight";
drivers/platform/x86/thinkpad_acpi.c:           .name           =
"tpacpi::kbd_backlight",
drivers/platform/x86/toshiba_acpi.c:            dev->kbd_led.name =
"toshiba::kbd_backlight";

and userspace already knows how to handle these.

Thanks.

-- 
Dmitry