linux-kernel - [PATCH v3 3/4] mfd: cros_ec: instantiate properly CrOS FP MCU device

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Date:   Mon,  8 Apr 2019 11:41:40 +0200
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     lee.jones@...aro.org
Cc:     gwendal@...omium.org, bleung@...omium.org,
        linux-kernel@...r.kernel.org, groeck@...omium.org,
        kernel@...labora.com, dtor@...omium.org,
        rushikesh.s.kadam@...el.com,
        Vincent Palatin <vpalatin@...omium.org>
Subject: [PATCH v3 3/4] mfd: cros_ec: instantiate properly CrOS FP MCU device

Support Fingerprint MCU as a special of CrOS EC devices. The current FP
MCU uses the same EC SPI protocol v3 as other CrOS EC devices on a SPI
bus.

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

Signed-off-by: Vincent Palatin <vpalatin@...omium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
---

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 1daccd4e05a3..79746e817cdb 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -636,6 +636,16 @@ static int ec_device_probe(struct platform_device *pdev)
 	device_initialize(&ec->class_dev);
 	cdev_init(&ec->cdev, &fops);
 
+	/* Check whether this is actually a Fingerprint MCU rather than an EC */
+	if (cros_ec_check_features(ec, EC_FEATURE_FINGERPRINT)) {
+		dev_info(dev, "CrOS Fingerprint MCU detected.\n");
+		/*
+		 * Help userspace differentiating ECs from FP MCU,
+		 * regardless of the probing order.
+		 */
+		ec_platform->ec_name = CROS_EC_DEV_FP_NAME;
+	}
+
 	/*
 	 * Check whether this is actually an Integrated Sensor Hub (ISH)
 	 * rather than an EC.
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index ce50628aa5e7..b393bd4e4b73 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -23,6 +23,7 @@
 #include <linux/mutex.h>
 
 #define CROS_EC_DEV_NAME	"cros_ec"
+#define CROS_EC_DEV_FP_NAME	"cros_fp"
 #define CROS_EC_DEV_ISH_NAME	"cros_ish"
 #define CROS_EC_DEV_PD_NAME	"cros_pd"
 
-- 
2.20.1