mfd: cros_ec_dev: Register cros-ec-rtc driver as a subdevice

Check whether this EC instance has RTC host command support and instatiate
the RTC driver as a subdevice in such case.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/cros_ec_dev.c

@@ -383,6 +383,10 @@ static void cros_ec_sensors_register(struct cros_ec_dev *ec)
 	kfree(msg);
 }
 
+static const struct mfd_cell cros_ec_rtc_cells[] = {
+	{ .name = "cros-ec-rtc" }
+};
+
 static int ec_device_probe(struct platform_device *pdev)
 {
 	int retval = -ENOMEM;
@@ -422,6 +426,18 @@ static int ec_device_probe(struct platform_device *pdev)
 	if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE))
 		cros_ec_sensors_register(ec);
 
+	/* Check whether this EC instance has RTC host command support */
+	if (cros_ec_check_features(ec, EC_FEATURE_RTC)) {
+		retval = mfd_add_devices(ec->dev, PLATFORM_DEVID_AUTO,
+					 cros_ec_rtc_cells,
+					 ARRAY_SIZE(cros_ec_rtc_cells),
+					 NULL, 0, NULL);
+		if (retval)
+			dev_err(ec->dev,
+				"failed to add cros-ec-rtc device: %d\n",
+				retval);
+	}
+
 	/* Take control of the lightbar from the EC. */
 	lb_manual_suspend_ctrl(ec, 1);