mfd: cros_ec: Instantiate properly CrOS ISH MCU device

Integrated Sensor Hub (ISH) is also a MCU running EC
having feature bit EC_FEATURE_ISH. Instantiate it as
a special CrOS EC device with device name 'cros_ish'.
Signed-off-by: Rushikesh S Kadam <rushikesh.s.kadam@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Acked-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/cros_ec_dev.c

@@ -418,6 +418,19 @@ static int ec_device_probe(struct platform_device *pdev)
 	device_initialize(&ec->class_dev);
 	cdev_init(&ec->cdev, &fops);
 
+	/*
+	 * Check whether this is actually an Integrated Sensor Hub (ISH)
+	 * rather than an EC.
+	 */
+	if (cros_ec_check_features(ec, EC_FEATURE_ISH)) {
+		dev_info(dev, "CrOS ISH MCU detected.\n");
+		/*
+		 * Help userspace differentiating ECs from ISH MCU,
+		 * regardless of the probing order.
+		 */
+		ec_platform->ec_name = CROS_EC_DEV_ISH_NAME;
+	}
+
 	/*
 	 * Add the class device
 	 * Link to the character device for creating the /dev entry

include/linux/mfd/cros_ec.h

@@ -24,6 +24,7 @@
 
 #define CROS_EC_DEV_NAME "cros_ec"
 #define CROS_EC_DEV_PD_NAME "cros_pd"
+#define CROS_EC_DEV_ISH_NAME "cros_ish"
 
 /*
  * The EC is unresponsive for a time after a reboot command.  Add a

include/linux/mfd/cros_ec_commands.h

@@ -856,6 +856,8 @@ enum ec_feature_code {
 	EC_FEATURE_RTC = 27,
 	/* EC supports CEC commands */
 	EC_FEATURE_CEC = 35,
+	/* The MCU is an Integrated Sensor Hub */
+	EC_FEATURE_ISH = 40,
 };
 
 #define EC_FEATURE_MASK_0(event_code) (1UL << (event_code % 32))