platform/chrome: lightbar: Add support for large sequence

Current sequences are limited to 192 bytes. Increase support to whatever
the EC support. If the sequence is too long, the EC will return an
OVERFLOW error.

Test: Check sending a large sequence is received by the EC.

Signed-off-by: Gwendal Grignou <gwendal@google.com>
Link: https://lore.kernel.org/r/20260130081351.487517-2-gwendal@google.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Author: gwendalcr

drivers/platform/chrome/cros_ec_lightbar.c

@@ -37,6 +37,11 @@ static bool userspace_control;
  */
 static bool has_manual_suspend;
 
+/*
+ * Lightbar version
+ */
+static int lb_version;
+
 static ssize_t interval_msec_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
@@ -93,18 +98,20 @@ static int lb_throttle(void)
 
 static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
 {
+	int len = max(ec->ec_dev->max_response, ec->ec_dev->max_request);
 	struct cros_ec_command *msg;
-	int len;
-
-	len = max(sizeof(struct ec_params_lightbar),
-		  sizeof(struct ec_response_lightbar));
 
 	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
 	if (!msg)
 		return NULL;
 
 	msg->version = 0;
 	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
+	/*
+	 * Default sizes for regular commands.
+	 * Can be set smaller to optimize transfer,
+	 * larger when sending large light sequences.
+	 */
 	msg->outsize = sizeof(struct ec_params_lightbar);
 	msg->insize = sizeof(struct ec_response_lightbar);
 
@@ -471,25 +478,34 @@ static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
 static ssize_t program_store(struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
-	int extra_bytes, max_size, ret;
+	size_t extra_bytes, max_size;
 	struct ec_params_lightbar *param;
 	struct cros_ec_command *msg;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
+	int ret;
 
 	/*
 	 * We might need to reject the program for size reasons. The EC
 	 * enforces a maximum program size, but we also don't want to try
 	 * and send a program that is too big for the protocol. In order
 	 * to ensure the latter, we also need to ensure we have extra bytes
 	 * to represent the rest of the packet.
+	 * With V3, larger program can be sent, limited only by the EC.
+	 * Only the protocol limit the payload size.
 	 */
-	extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
-	max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
-	if (count > max_size) {
-		dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
-			(unsigned int)count, max_size);
-
-		return -EINVAL;
+	if (lb_version < 3) {
+		extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
+		max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
+		if (count > max_size) {
+			dev_err(dev, "Program is %zu bytes, too long to send (max: %zu)",
+				count, max_size);
+
+			return -EINVAL;
+		}
+	} else {
+		extra_bytes = offsetof(typeof(*param), set_program_ex) +
+			sizeof(param->set_program_ex);
+		max_size = ec->ec_dev->max_request - extra_bytes;
 	}
 
 	msg = alloc_lightbar_cmd_msg(ec);
@@ -499,26 +515,44 @@ static ssize_t program_store(struct device *dev, struct device_attribute *attr,
 	ret = lb_throttle();
 	if (ret)
 		goto exit;
+	param = (struct ec_params_lightbar *)msg->data;
 
-	dev_info(dev, "Copying %zu byte program to EC", count);
+	if (lb_version < 3) {
+		dev_info(dev, "Copying %zu byte program to EC", count);
 
-	param = (struct ec_params_lightbar *)msg->data;
-	param->cmd = LIGHTBAR_CMD_SET_PROGRAM;
+		param->cmd = LIGHTBAR_CMD_SET_PROGRAM;
 
-	param->set_program.size = count;
-	memcpy(param->set_program.data, buf, count);
+		param->set_program.size = count;
+		memcpy(param->set_program.data, buf, count);
 
-	/*
-	 * We need to set the message size manually or else it will use
-	 * EC_LB_PROG_LEN. This might be too long, and the program
-	 * is unlikely to use all of the space.
-	 */
-	msg->outsize = count + extra_bytes;
+		/*
+		 * We need to set the message size manually or else it will use
+		 * EC_LB_PROG_LEN. This might be too long, and the program
+		 * is unlikely to use all of the space.
+		 */
+		msg->outsize = count + extra_bytes;
 
-	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
-	if (ret < 0)
-		goto exit;
+		ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
+		if (ret < 0)
+			goto exit;
+	} else {
+		size_t offset = 0;
+		size_t payload = 0;
+
+		param->cmd = LIGHTBAR_CMD_SET_PROGRAM_EX;
+		while (offset < count) {
+			payload = min(max_size, count - offset);
+			param->set_program_ex.offset = offset;
+			param->set_program_ex.size = payload;
+			memcpy(param->set_program_ex.data, &buf[offset], payload);
+			msg->outsize = payload + extra_bytes;
 
+			ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
+			if (ret < 0)
+				goto exit;
+			offset += payload;
+		}
+	}
 	ret = count;
 exit:
 	kfree(msg);
@@ -596,7 +630,7 @@ static int cros_ec_lightbar_probe(struct platform_device *pd)
 	 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
 	 * doesn't have a lightbar.
 	 */
-	if (!get_lightbar_version(ec_dev, NULL, NULL))
+	if (!get_lightbar_version(ec_dev, &lb_version, NULL))
 		return -ENODEV;
 
 	/* Take control of the lightbar from the EC. */

include/linux/platform_data/cros_ec_commands.h

@@ -2020,6 +2020,17 @@ struct lightbar_program {
 	uint8_t data[EC_LB_PROG_LEN];
 } __ec_todo_unpacked;
 
+/*
+ * Lightbar program for large sequences. Sequences are sent in pieces, with
+ * increasing offset. The sequences are still limited by the amount reserved in
+ * EC RAM.
+ */
+struct lightbar_program_ex {
+	uint16_t offset;
+	uint8_t size;
+	uint8_t data[0];
+} __ec_todo_unpacked;
+
 struct ec_params_lightbar {
 	uint8_t cmd;		      /* Command (see enum lightbar_command) */
 	union {
@@ -2066,6 +2077,7 @@ struct ec_params_lightbar {
 		struct lightbar_params_v2_colors set_v2par_colors;
 
 		struct lightbar_program set_program;
+		struct lightbar_program_ex set_program_ex;
 	};
 } __ec_todo_packed;
 
@@ -2154,6 +2166,7 @@ enum lightbar_command {
 	LIGHTBAR_CMD_GET_PARAMS_V2_COLORS = 32,
 	LIGHTBAR_CMD_SET_PARAMS_V2_COLORS = 33,
 	LIGHTBAR_CMD_GET_PARAMS_V3 = 34,
+	LIGHTBAR_CMD_SET_PROGRAM_EX = 35,
 	LIGHTBAR_NUM_CMDS
 };