iio: common: cros_ec_sensors: determine protocol version

This patch adds a function to determine which version of the
protocol is used to communicate with EC.
Signed-off-by: Nick Vaccaro <nvaccaro@chromium.org>
Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
[rebased on top of iio/testing and solved conflicts]
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c

@@ -25,6 +25,31 @@ static char *cros_ec_loc[] = {
 	[MOTIONSENSE_LOC_MAX] = "unknown",
 };
 
+static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
+					     u16 cmd_offset, u16 cmd, u32 *mask)
+{
+	int ret;
+	struct {
+		struct cros_ec_command msg;
+		union {
+			struct ec_params_get_cmd_versions params;
+			struct ec_response_get_cmd_versions resp;
+		};
+	} __packed buf = {
+		.msg = {
+			.command = EC_CMD_GET_CMD_VERSIONS + cmd_offset,
+			.insize = sizeof(struct ec_response_get_cmd_versions),
+			.outsize = sizeof(struct ec_params_get_cmd_versions)
+			},
+		.params = {.cmd = cmd}
+	};
+
+	ret = cros_ec_cmd_xfer_status(ec_dev, &buf.msg);
+	if (ret >= 0)
+		*mask = buf.resp.version_mask;
+	return ret;
+}
+
 int cros_ec_sensors_core_init(struct platform_device *pdev,
 			      struct iio_dev *indio_dev,
 			      bool physical_device)
@@ -33,6 +58,7 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
 	struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
 	struct cros_ec_dev *ec = dev_get_drvdata(pdev->dev.parent);
 	struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
+	u32 ver_mask;
 	int ret;
 
 	platform_set_drvdata(pdev, indio_dev);
@@ -48,8 +74,15 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
 
 	mutex_init(&state->cmd_lock);
 
+	ret = cros_ec_get_host_cmd_version_mask(state->ec,
+						ec->cmd_offset,
+						EC_CMD_MOTION_SENSE_CMD,
+						&ver_mask);
+	if (ret < 0)
+		return ret;
+
 	/* Set up the host command structure. */
-	state->msg->version = 2;
+	state->msg->version = fls(ver_mask) - 1;
 	state->msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
 	state->msg->outsize = sizeof(struct ec_params_motion_sense);