platform/chrome: wilco_ec: Add batt_ppid_info command to telemetry driver

Add the GET_BATT_PPID_INFO=0x8A command to the allowlist of accepted
telemetry commands. In addition, since this new command requires
verifying the contents of some of the arguments, I also restructure
the request to use a union of the argument structs. Also, zero out the
request buffer before each request, and change "whitelist" to
"allowlist".

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

drivers/platform/chrome/wilco_ec/telemetry.c

@@ -9,7 +9,7 @@
  * the OS sends a command to the EC via a write() to a char device,
  * and can read the response with a read(). The write() request is
  * verified by the driver to ensure that it is performing only one
- * of the whitelisted commands, and that no extraneous data is
+ * of the allowlisted commands, and that no extraneous data is
  * being transmitted to the EC. The response is passed directly
  * back to the reader with no modification.
  *
@@ -59,21 +59,10 @@ static DEFINE_IDA(telem_ida);
 #define WILCO_EC_TELEM_GET_TEMP_INFO		0x95
 #define WILCO_EC_TELEM_GET_TEMP_READ		0x2C
 #define WILCO_EC_TELEM_GET_BATT_EXT_INFO	0x07
+#define WILCO_EC_TELEM_GET_BATT_PPID_INFO	0x8A
 
 #define TELEM_ARGS_SIZE_MAX	30
 
-/**
- * struct wilco_ec_telem_request - Telemetry command and arguments sent to EC.
- * @command: One of WILCO_EC_TELEM_GET_* command codes.
- * @reserved: Must be 0.
- * @args: The first N bytes are one of telem_args_get_* structs, the rest is 0.
- */
-struct wilco_ec_telem_request {
-	u8 command;
-	u8 reserved;
-	u8 args[TELEM_ARGS_SIZE_MAX];
-} __packed;
-
 /*
  * The following telem_args_get_* structs are embedded within the |args| field
  * of wilco_ec_telem_request.
@@ -122,6 +111,32 @@ struct telem_args_get_batt_ext_info {
 	u8 var_args[5];
 } __packed;
 
+struct telem_args_get_batt_ppid_info {
+	u8 always1; /* Should always be 1 */
+} __packed;
+
+/**
+ * struct wilco_ec_telem_request - Telemetry command and arguments sent to EC.
+ * @command: One of WILCO_EC_TELEM_GET_* command codes.
+ * @reserved: Must be 0.
+ * @args: The first N bytes are one of telem_args_get_* structs, the rest is 0.
+ */
+struct wilco_ec_telem_request {
+	u8 command;
+	u8 reserved;
+	union {
+		u8 buf[TELEM_ARGS_SIZE_MAX];
+		struct telem_args_get_log		get_log;
+		struct telem_args_get_version		get_version;
+		struct telem_args_get_fan_info		get_fan_info;
+		struct telem_args_get_diag_info		get_diag_info;
+		struct telem_args_get_temp_info		get_temp_info;
+		struct telem_args_get_temp_read		get_temp_read;
+		struct telem_args_get_batt_ext_info	get_batt_ext_info;
+		struct telem_args_get_batt_ppid_info	get_batt_ppid_info;
+	} args;
+} __packed;
+
 /**
  * check_telem_request() - Ensure that a request from userspace is valid.
  * @rq: Request buffer copied from userspace.
@@ -133,7 +148,7 @@ struct telem_args_get_batt_ext_info {
  * We do not want to allow userspace to send arbitrary telemetry commands to
  * the EC. Therefore we check to ensure that
  * 1. The request follows the format of struct wilco_ec_telem_request.
- * 2. The supplied command code is one of the whitelisted commands.
+ * 2. The supplied command code is one of the allowlisted commands.
  * 3. The request only contains the necessary data for the header and arguments.
  */
 static int check_telem_request(struct wilco_ec_telem_request *rq,
@@ -146,25 +161,31 @@ static int check_telem_request(struct wilco_ec_telem_request *rq,
 
 	switch (rq->command) {
 	case WILCO_EC_TELEM_GET_LOG:
-		max_size += sizeof(struct telem_args_get_log);
+		max_size += sizeof(rq->args.get_log);
 		break;
 	case WILCO_EC_TELEM_GET_VERSION:
-		max_size += sizeof(struct telem_args_get_version);
+		max_size += sizeof(rq->args.get_version);
 		break;
 	case WILCO_EC_TELEM_GET_FAN_INFO:
-		max_size += sizeof(struct telem_args_get_fan_info);
+		max_size += sizeof(rq->args.get_fan_info);
 		break;
 	case WILCO_EC_TELEM_GET_DIAG_INFO:
-		max_size += sizeof(struct telem_args_get_diag_info);
+		max_size += sizeof(rq->args.get_diag_info);
 		break;
 	case WILCO_EC_TELEM_GET_TEMP_INFO:
-		max_size += sizeof(struct telem_args_get_temp_info);
+		max_size += sizeof(rq->args.get_temp_info);
 		break;
 	case WILCO_EC_TELEM_GET_TEMP_READ:
-		max_size += sizeof(struct telem_args_get_temp_read);
+		max_size += sizeof(rq->args.get_temp_read);
 		break;
 	case WILCO_EC_TELEM_GET_BATT_EXT_INFO:
-		max_size += sizeof(struct telem_args_get_batt_ext_info);
+		max_size += sizeof(rq->args.get_batt_ext_info);
+		break;
+	case WILCO_EC_TELEM_GET_BATT_PPID_INFO:
+		if (rq->args.get_batt_ppid_info.always1 != 1)
+			return -EINVAL;
+
+		max_size += sizeof(rq->args.get_batt_ppid_info);
 		break;
 	default:
 		return -EINVAL;
@@ -250,6 +271,7 @@ static ssize_t telem_write(struct file *filp, const char __user *buf,
 
 	if (count > sizeof(sess_data->request))
 		return -EMSGSIZE;
+	memset(&sess_data->request, 0, sizeof(sess_data->request));
 	if (copy_from_user(&sess_data->request, buf, count))
 		return -EFAULT;
 	ret = check_telem_request(&sess_data->request, count);