[PATCH v6 03/14] HID: hid-sensor-hub: introduce device managed API

[Sanjay Chitroda via B4 Relay]

From: Sanjay Chitroda <sanjayembeddedse@xxxxxxxxx>

sensor_hub_register_callback() is common API used for the HID IIO drivers,
prepare devm API devm_sensor_hub_register_callback() to acquire resource
during setup and release using device managed framework during drivers
fail, unbind or remove path.

Store the required callback removal context (hsdev and usage_id) in a
dedicated struct sensor_hub_cb_devres, and register resources with
devres framework and helper API.

Suggested-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Sanjay Chitroda <sanjayembeddedse@xxxxxxxxx>
---
Changes in v6:
- Add kernel-doc for return statement for the new devm_*() API, as
  suggested by Andy.
- Keep kernel-doc for new devm_*() API in public header file, along
  side where existing API documentation is available.
- With suggestion/input from Jonathan, use devres and cleanup frameworks
  together to implement device managed API support with less complexity.
---
 drivers/hid/hid-sensor-hub.c   | 35 +++++++++++++++++++++++++++++++++++
 include/linux/hid-sensor-hub.h | 26 ++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/drivers/hid/hid-sensor-hub.c b/drivers/hid/hid-sensor-hub.c
index 6470a290ebfc..de35e72b4d88 100644
--- a/drivers/hid/hid-sensor-hub.c
+++ b/drivers/hid/hid-sensor-hub.c
@@ -4,7 +4,9 @@
  * Copyright (c) 2012, Intel Corporation.
  */
 
+#include <linux/cleanup.h>
 #include <linux/device.h>
+#include <linux/device/devres.h>
 #include <linux/hid.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -187,6 +189,39 @@ int sensor_hub_remove_callback(struct hid_sensor_hub_device *hsdev,
 }
 EXPORT_SYMBOL_GPL(sensor_hub_remove_callback);
 
+DEFINE_FREE(devres_free, struct sensor_hub_cb_devres *, if (_T) devres_free(_T))
+
+static void devm_sensor_hub_remove_callback(struct device *dev, void *res)
+{
+	struct sensor_hub_cb_devres *dr = res;
+
+	sensor_hub_remove_callback(dr->hsdev, dr->usage_id);
+}
+
+int devm_sensor_hub_register_callback(struct device *dev,
+				      struct hid_sensor_hub_device *hsdev,
+				      u32 usage_id,
+				      struct hid_sensor_hub_callbacks *usage_callback)
+{
+	struct sensor_hub_cb_devres *dr __free(devres_free) = NULL;
+	int ret;
+
+	dr = devres_alloc(devm_sensor_hub_remove_callback, sizeof(*dr), GFP_KERNEL);
+	if (!dr)
+		return -ENOMEM;
+
+	ret = sensor_hub_register_callback(hsdev, usage_id, usage_callback);
+	if (ret)
+		return ret;
+
+	dr->hsdev = hsdev;
+	dr->usage_id = usage_id;
+	devres_add(dev, no_free_ptr(dr));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_sensor_hub_register_callback);
+
 int sensor_hub_set_feature(struct hid_sensor_hub_device *hsdev, u32 report_id,
 			   u32 field_index, int buffer_size, void *buffer)
 {
diff --git a/include/linux/hid-sensor-hub.h b/include/linux/hid-sensor-hub.h
index ab5cc8db3fbb..aa4ff9a95d86 100644
--- a/include/linux/hid-sensor-hub.h
+++ b/include/linux/hid-sensor-hub.h
@@ -79,6 +79,16 @@ struct hid_sensor_hub_device {
 	struct sensor_hub_pending pending;
 };
 
+/**
+ * struct sensor_hub_cb_devres - devres data for sensor hub callbacks
+ * @hsdev:	Hub device instance.
+ * @usage_id:	Usage ID associated with registered callback
+ */
+struct sensor_hub_cb_devres {
+	struct hid_sensor_hub_device *hsdev;
+	u32 usage_id;
+};
+
 /**
  * struct hid_sensor_hub_callbacks - Client callback functions
  * @pdev:		Platform device instance of the client driver.
@@ -143,6 +153,22 @@ int sensor_hub_register_callback(struct hid_sensor_hub_device *hsdev,
 int sensor_hub_remove_callback(struct hid_sensor_hub_device *hsdev,
 			u32 usage_id);
 
+/**
+ * devm_sensor_hub_register_callback() - Managed register client callbacks
+ * @dev: Device for resource management
+ * @hsdev: Hub device instance
+ * @usage_id: Usage id of the client (e.g. 0x200076 for Gyro)
+ * @usage_callback: Callback function storage
+ *
+ * This is the devres (managed) version of sensor_hub_register_callback().
+ * The callback will be automatically unregistered when the device is detached.
+
+ * Return: 0 on success, negative error code on failure.
+ */
+int devm_sensor_hub_register_callback(struct device *dev,
+				      struct hid_sensor_hub_device *hsdev,
+				      u32 usage_id,
+				      struct hid_sensor_hub_callbacks *usage_callback);
 
 /* Hid sensor hub core interfaces */
 

-- 
2.34.1