[PATCH v3 1/1] platform/chrome: Poke kb_wake_angle attribute visibility when needed

[Gwendal Grignou <gwendal@chromium.org>]

When the sensorhub detects 2 accelerometers, kb_wake_angle attribute
in the chromeos EC class device needs to be visible.
When detected, the sensorhub requests the class device to
revisit the visibility of the kb_wake_angle attribute.
Expose the attribute group to alter to close a potiential race between
cros-ec-sensorhub and cros-ec-sysfs (that creates the attribute group
on behalf of the class driver).

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
 drivers/platform/chrome/cros_ec_sensorhub.c | 6 +++++-
 drivers/platform/chrome/cros_ec_sysfs.c     | 5 +++--
 include/linux/platform_data/cros_ec_proto.h | 2 ++
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_sensorhub.c b/drivers/platform/chrome/cros_ec_sensorhub.c
index 9c4af76a9956e..8f24ed90b229c 100644
--- a/drivers/platform/chrome/cros_ec_sensorhub.c
+++ b/drivers/platform/chrome/cros_ec_sensorhub.c
@@ -106,8 +106,12 @@ static int cros_ec_sensorhub_register(struct device *dev,
 		sensor_type[sensorhub->resp->info.type]++;
 	}
 
-	if (sensor_type[MOTIONSENSE_TYPE_ACCEL] >= 2)
+	if (sensor_type[MOTIONSENSE_TYPE_ACCEL] >= 2) {
 		ec->has_kb_wake_angle = true;
+		if (ec->group && sysfs_update_group(&ec->class_dev.kobj,
+						    ec->group))
+			dev_warn(dev, "Unable to update cros-ec-sysfs");
+	}
 
 	if (cros_ec_check_features(ec,
 				   EC_FEATURE_REFINED_TABLET_MODE_HYSTERESIS)) {
diff --git a/drivers/platform/chrome/cros_ec_sysfs.c b/drivers/platform/chrome/cros_ec_sysfs.c
index f07eabcf9494c..17fe657f3ffd5 100644
--- a/drivers/platform/chrome/cros_ec_sysfs.c
+++ b/drivers/platform/chrome/cros_ec_sysfs.c
@@ -341,7 +341,8 @@ static int cros_ec_sysfs_probe(struct platform_device *pd)
 	struct device *dev = &pd->dev;
 	int ret;
 
-	ret = sysfs_create_group(&ec_dev->class_dev.kobj, &cros_ec_attr_group);
+	ec_dev->group = &cros_ec_attr_group;
+	ret = sysfs_create_group(&ec_dev->class_dev.kobj, ec_dev->group);
 	if (ret < 0)
 		dev_err(dev, "failed to create attributes. err=%d\n", ret);
 
@@ -352,7 +353,7 @@ static int cros_ec_sysfs_remove(struct platform_device *pd)
 {
 	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
 
-	sysfs_remove_group(&ec_dev->class_dev.kobj, &cros_ec_attr_group);
+	sysfs_remove_group(&ec_dev->class_dev.kobj, ec_dev->group);
 
 	return 0;
 }
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index 02599687770c5..c6dca260bbd5d 100644
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -191,6 +191,7 @@ struct cros_ec_platform {
 /**
  * struct cros_ec_dev - ChromeOS EC device entry point.
  * @class_dev: Device structure used in sysfs.
+ * @groups: sysfs attributes groups for this EC.
  * @ec_dev: cros_ec_device structure to talk to the physical device.
  * @dev: Pointer to the platform device.
  * @debug_info: cros_ec_debugfs structure for debugging information.
@@ -200,6 +201,7 @@ struct cros_ec_platform {
  */
 struct cros_ec_dev {
 	struct device class_dev;
+	const struct attribute_group *group;
 	struct cros_ec_device *ec_dev;
 	struct device *dev;
 	struct cros_ec_debugfs *debug_info;
-- 
2.32.0.554.ge1b32706d8-goog