linux-kernel - [RFC v3 5/5] cros_ec: differentiate SCP from EC by feature bit.

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Message-Id: <20190121071833.43443-6-pihsun@chromium.org>
Date:   Mon, 21 Jan 2019 15:18:33 +0800
From:   Pi-Hsun Shih <pihsun@...omium.org>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Pi-Hsun Shih <pihsun@...omium.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Enric Balletbo Serra <eballetbo@...il.com>,
        Guenter Roeck <groeck@...omium.org>,
        Lee Jones <lee.jones@...aro.org>,
        Benson Leung <bleung@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [RFC v3 5/5] cros_ec: differentiate SCP from EC by feature bit.

Since a SCP and EC would both exist on a system, and use the cros_ec_dev
driver, we need to differentiate between them for the userspace, or they
would both be registered at /dev/cros_ec, causing a conflict.

Cc: Enric Balletbo Serra <eballetbo@...il.com>
Cc: Guenter Roeck <groeck@...omium.org>
Signed-off-by: Pi-Hsun Shih <pihsun@...omium.org>
---
Changes from v2:
 - No change.

Changes from v1:
 - New patch extracted from Patch 5.
---
 drivers/mfd/cros_ec_dev.c            | 9 +++++++++
 include/linux/mfd/cros_ec.h          | 1 +
 include/linux/mfd/cros_ec_commands.h | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 2d0fee488c5aa8..67983853413d07 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -414,6 +414,15 @@ static int ec_device_probe(struct platform_device *pdev)
 	device_initialize(&ec->class_dev);
 	cdev_init(&ec->cdev, &fops);
 
+	if (cros_ec_check_features(ec, EC_FEATURE_SCP)) {
+		dev_info(dev, "SCP detected.\n");
+		/*
+		 * Help userspace differentiating ECs from SCP,
+		 * regardless of the probing order.
+		 */
+		ec_platform->ec_name = CROS_EC_DEV_SCP_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 de8b588c8776da..fd297cf8f97295 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/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_SCP_NAME "cros_scp"
 
 /*
  * The EC is unresponsive for a time after a reboot command.  Add a
diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
index fc91082d4c357b..3e5da6e93b2f42 100644
--- a/include/linux/mfd/cros_ec_commands.h
+++ b/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 exposes a SCP */
+	EC_FEATURE_SCP = 39,
 };
 
 #define EC_FEATURE_MASK_0(event_code) (1UL << (event_code % 32))
-- 
2.20.1.321.g9e740568ce-goog