platform/chrome: cros_ec_debugfs: Avoid -Wflex-array-member-not-at-end warnings

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.

So, with these changes, fix the following warnings:

drivers/platform/chrome/cros_ec_debugfs.c:211:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
drivers/platform/chrome/cros_ec_debugfs.c:257:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
drivers/platform/chrome/cros_ec_debugfs.c:279:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/Z-aiAAcIP7sBRtz0@kspp
Signed-off-by: Tzung-Bi Shih <[email protected]>

Author: GustavoARSilva

drivers/platform/chrome/cros_ec_debugfs.c

@@ -207,22 +207,15 @@ static ssize_t cros_ec_pdinfo_read(struct file *file,
 	char read_buf[EC_USB_PD_MAX_PORTS * 40], *p = read_buf;
 	struct cros_ec_debugfs *debug_info = file->private_data;
 	struct cros_ec_device *ec_dev = debug_info->ec->ec_dev;
-	struct {
-		struct cros_ec_command msg;
-		union {
-			struct ec_response_usb_pd_control_v1 resp;
-			struct ec_params_usb_pd_control params;
-		};
-	} __packed ec_buf;
-	struct cros_ec_command *msg;
-	struct ec_response_usb_pd_control_v1 *resp;
-	struct ec_params_usb_pd_control *params;
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			MAX(sizeof(struct ec_response_usb_pd_control_v1),
+			    sizeof(struct ec_params_usb_pd_control)));
+	struct ec_response_usb_pd_control_v1 *resp =
+			(struct ec_response_usb_pd_control_v1 *)msg->data;
+	struct ec_params_usb_pd_control *params =
+			(struct ec_params_usb_pd_control *)msg->data;
 	int i;
 
-	msg = &ec_buf.msg;
-	params = (struct ec_params_usb_pd_control *)msg->data;
-	resp = (struct ec_response_usb_pd_control_v1 *)msg->data;
-
 	msg->command = EC_CMD_USB_PD_CONTROL;
 	msg->version = 1;
 	msg->insize = sizeof(*resp);
@@ -253,17 +246,15 @@ static ssize_t cros_ec_pdinfo_read(struct file *file,
 
 static bool cros_ec_uptime_is_supported(struct cros_ec_device *ec_dev)
 {
-	struct {
-		struct cros_ec_command cmd;
-		struct ec_response_uptime_info resp;
-	} __packed msg = {};
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			sizeof(struct ec_response_uptime_info));
 	int ret;
 
-	msg.cmd.command = EC_CMD_GET_UPTIME_INFO;
-	msg.cmd.insize = sizeof(msg.resp);
+	msg->command = EC_CMD_GET_UPTIME_INFO;
+	msg->insize = sizeof(struct ec_response_uptime_info);
 
-	ret = cros_ec_cmd_xfer_status(ec_dev, &msg.cmd);
-	if (ret == -EPROTO && msg.cmd.result == EC_RES_INVALID_COMMAND)
+	ret = cros_ec_cmd_xfer_status(ec_dev, msg);
+	if (ret == -EPROTO && msg->result == EC_RES_INVALID_COMMAND)
 		return false;
 
 	/* Other errors maybe a transient error, do not rule about support. */
@@ -275,20 +266,17 @@ static ssize_t cros_ec_uptime_read(struct file *file, char __user *user_buf,
 {
 	struct cros_ec_debugfs *debug_info = file->private_data;
 	struct cros_ec_device *ec_dev = debug_info->ec->ec_dev;
-	struct {
-		struct cros_ec_command cmd;
-		struct ec_response_uptime_info resp;
-	} __packed msg = {};
-	struct ec_response_uptime_info *resp;
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			sizeof(struct ec_response_uptime_info));
+	struct ec_response_uptime_info *resp =
+				(struct ec_response_uptime_info *)msg->data;
 	char read_buf[32];
 	int ret;
 
-	resp = (struct ec_response_uptime_info *)&msg.resp;
-
-	msg.cmd.command = EC_CMD_GET_UPTIME_INFO;
-	msg.cmd.insize = sizeof(*resp);
+	msg->command = EC_CMD_GET_UPTIME_INFO;
+	msg->insize = sizeof(*resp);
 
-	ret = cros_ec_cmd_xfer_status(ec_dev, &msg.cmd);
+	ret = cros_ec_cmd_xfer_status(ec_dev, msg);
 	if (ret < 0)
 		return ret;