mfd: cros_ec: Instantiate sub-devices from device tree

If the EC device tree node has sub-nodes, try to instantiate them as
MFD sub-devices.  We can configure the EC features provided by the board.
Signed-off-by: Todd Broch <tbroch@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/cros_ec.c

@@ -17,6 +17,7 @@
  * battery charging and regulator control, firmware update.
  */
 
+#include <linux/of_platform.h>
 #include <linux/interrupt.h>
 #include <linux/slab.h>
 #include <linux/module.h>
@@ -108,19 +109,9 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
 EXPORT_SYMBOL(cros_ec_cmd_xfer);
 
 static const struct mfd_cell cros_devs[] = {
-	{
-		.name = "cros-ec-keyb",
-		.id = 1,
-		.of_compatible = "google,cros-ec-keyb",
-	},
-	{
-		.name = "cros-ec-i2c-tunnel",
-		.id = 2,
-		.of_compatible = "google,cros-ec-i2c-tunnel",
-	},
 	{
 		.name = "cros-ec-ctl",
-		.id = 3,
+		.id = PLATFORM_DEVID_AUTO,
 	},
 };
 
@@ -150,6 +141,15 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 		return err;
 	}
 
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+		err = of_platform_populate(dev->of_node, NULL, NULL, dev);
+		if (err) {
+			mfd_remove_devices(dev);
+			dev_err(dev, "Failed to register sub-devices\n");
+			return err;
+		}
+	}
+
 	dev_info(dev, "Chrome EC device registered\n");
 
 	return 0;