HID: Delay opening HID device

Don't call hid_open_device till there is actually an user. This saves
power by not opening underlying transport for HID. Also close device
if there are no active mfd client using HID sensor hub.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/hid/hid-sensor-hub.c

@@ -465,6 +465,39 @@ static int sensor_hub_raw_event(struct hid_device *hdev,
 	return 1;
 }
 
+int sensor_hub_device_open(struct hid_sensor_hub_device *hsdev)
+{
+	int ret = 0;
+	struct sensor_hub_data *data =  hid_get_drvdata(hsdev->hdev);
+
+	mutex_lock(&data->mutex);
+	if (!hsdev->ref_cnt) {
+		ret = hid_hw_open(hsdev->hdev);
+		if (ret) {
+			hid_err(hsdev->hdev, "failed to open hid device\n");
+			mutex_unlock(&data->mutex);
+			return ret;
+		}
+	}
+	hsdev->ref_cnt++;
+	mutex_unlock(&data->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sensor_hub_device_open);
+
+void sensor_hub_device_close(struct hid_sensor_hub_device *hsdev)
+{
+	struct sensor_hub_data *data =  hid_get_drvdata(hsdev->hdev);
+
+	mutex_lock(&data->mutex);
+	hsdev->ref_cnt--;
+	if (!hsdev->ref_cnt)
+		hid_hw_close(hsdev->hdev);
+	mutex_unlock(&data->mutex);
+}
+EXPORT_SYMBOL_GPL(sensor_hub_device_close);
+
 static int sensor_hub_probe(struct hid_device *hdev,
 				const struct hid_device_id *id)
 {
@@ -506,12 +539,6 @@ static int sensor_hub_probe(struct hid_device *hdev,
 		hid_err(hdev, "hw start failed\n");
 		return ret;
 	}
-	ret = hid_hw_open(hdev);
-	if (ret) {
-		hid_err(hdev, "failed to open input interrupt pipe\n");
-		goto err_stop_hw;
-	}
-
 	INIT_LIST_HEAD(&sd->dyn_callback_list);
 	sd->hid_sensor_client_cnt = 0;
 	report_enum = &hdev->report_enum[HID_INPUT_REPORT];
@@ -520,7 +547,7 @@ static int sensor_hub_probe(struct hid_device *hdev,
 	if (dev_cnt > HID_MAX_PHY_DEVICES) {
 		hid_err(hdev, "Invalid Physical device count\n");
 		ret = -EINVAL;
-		goto err_close;
+		goto err_stop_hw;
 	}
 	sd->hid_sensor_hub_client_devs = kzalloc(dev_cnt *
 						sizeof(struct mfd_cell),
@@ -528,7 +555,7 @@ static int sensor_hub_probe(struct hid_device *hdev,
 	if (sd->hid_sensor_hub_client_devs == NULL) {
 		hid_err(hdev, "Failed to allocate memory for mfd cells\n");
 			ret = -ENOMEM;
-			goto err_close;
+			goto err_stop_hw;
 	}
 	list_for_each_entry(report, &report_enum->report_list, list) {
 		hid_dbg(hdev, "Report id:%x\n", report->id);
@@ -565,8 +592,6 @@ err_free_names:
 	for (i = 0; i < sd->hid_sensor_client_cnt ; ++i)
 		kfree(sd->hid_sensor_hub_client_devs[i].name);
 	kfree(sd->hid_sensor_hub_client_devs);
-err_close:
-	hid_hw_close(hdev);
 err_stop_hw:
 	hid_hw_stop(hdev);
 

include/linux/hid-sensor-hub.h

@@ -47,11 +47,13 @@ struct hid_sensor_hub_attribute_info {
  * @hdev:		Stores the hid instance.
  * @vendor_id:		Vendor id of hub device.
  * @product_id:		Product id of hub device.
+ * @ref_cnt:		Number of MFD clients have opened this device
  */
 struct hid_sensor_hub_device {
 	struct hid_device *hdev;
 	u32 vendor_id;
 	u32 product_id;
+	int ref_cnt;
 };
 
 /**
@@ -74,6 +76,22 @@ struct hid_sensor_hub_callbacks {
 			 void *priv);
 };
 
+/**
+* sensor_hub_device_open() - Open hub device
+* @hsdev:	Hub device instance.
+*
+* Used to open hid device for sensor hub.
+*/
+int sensor_hub_device_open(struct hid_sensor_hub_device *hsdev);
+
+/**
+* sensor_hub_device_clode() - Close hub device
+* @hsdev:	Hub device instance.
+*
+* Used to clode hid device for sensor hub.
+*/
+void sensor_hub_device_close(struct hid_sensor_hub_device *hsdev);
+
 /* Registration functions */
 
 /**