[PATCH v4 3/3] mfd: cros_ec: instantiate properly CrOS Touchpad MCU device

[Enric Balletbo i Serra]

Support Touchpad MCU as a special of CrOS EC devices. The current
Touchpad MCU is used on Eve Chromebook and used the same protocol as
other CrOS EC devices.

When a MCU has touchpad support (aka EC_FEATURE_TOUCHPAD), it is
instantiated as a special CrOS EC device with device name 'cros_tp'. So
regardless of the probing order between the actual cros_ec and cros_tp,
the userspace and other kernel drivers should not confuse them.

Signed-off-by: Wei-Ning Huang <wnhuang@xxxxxxxxxx>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
---

Changes in v4: None
Changes in v3: None
Changes in v2: None

 drivers/mfd/cros_ec_dev.c   | 10 ++++++++++
 include/linux/mfd/cros_ec.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 71a01a096595..54a58df571b6 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -442,6 +442,16 @@ static int ec_device_probe(struct platform_device *pdev)
 		ec_platform->ec_name = CROS_EC_DEV_ISH_NAME;
 	}
 
+	/* Check whether this is actually a Touchpad MCU rather than an EC */
+	if (cros_ec_check_features(ec, EC_FEATURE_TOUCHPAD)) {
+		dev_info(dev, "CrOS Touchpad MCU detected.\n");
+		/*
+		 * Help userspace differentiating ECs from TP MCU,
+		 * regardless of the probing order.
+		 */
+		ec_platform->ec_name = CROS_EC_DEV_TP_NAME;
+	}
+
 	/*
 	 * Add the class device
 	 * Link to the character device for creating the /dev entry
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 20fb5f298f73..2acbbec75eeb 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -25,6 +25,7 @@
 #define CROS_EC_DEV_NAME "cros_ec"
 #define CROS_EC_DEV_FP_NAME "cros_fp"
 #define CROS_EC_DEV_PD_NAME "cros_pd"
+#define CROS_EC_DEV_TP_NAME "cros_tp"
 #define CROS_EC_DEV_ISH_NAME "cros_ish"
 
 /*
-- 
2.20.1