linux-kernel - [PATCH 2/2] mfd: cros_ec: instantiate properly CrOS Touchpad MCU device

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Message-Id: <20190307175253.14785-3-enric.balletbo@collabora.com>
Date:   Thu,  7 Mar 2019 18:52:53 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     lee.jones@...aro.org
Cc:     groeck@...omium.org, gwendal@...omium.org, kernel@...labora.com,
        bleung@...omium.org, linux-kernel@...r.kernel.org,
        Wei-Ning Huang <wnhuang@...gle.com>
Subject: [PATCH 2/2] mfd: cros_ec: instantiate properly CrOS Touchpad MCU device

From: Wei-Ning Huang <wnhuang@...gle.com>

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@...gle.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
---

 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 51b318cbc0ed..dd49dd3956be 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -667,6 +667,16 @@ 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