[PATCH v2] HID: hyperv: Add the support of hibernation

[Dexuan Cui <decui@microsoft.com>]

During the suspend process and resume process, if there is any mouse
event, there is a small chance the suspend and the resume process can be
aborted because of mousevsc_on_receive() -> pm_wakeup_hard_event().

This behavior can be avoided by disabling the Hyper-V mouse device as
a wakeup source:

echo disabled > /sys/bus/vmbus/drivers/hid_hyperv/XXX/power/wakeup
(XXX is the device's GUID).

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
---

Changes in v2:
  Removed the "struct notifier_block pm_nb;" after the discussion
with Dmitry Torokhov:
  https://lore.kernel.org/lkml/PU1P153MB016914A7C827CA35D7FEB66ABF8B0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM/T/#m8948c711301220a36a1a413eead74cd2fb6dcac1

 drivers/hid/hid-hyperv.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
index 79a28fc91521..dddfca555df9 100644
--- a/drivers/hid/hid-hyperv.c
+++ b/drivers/hid/hid-hyperv.c
@@ -192,6 +192,9 @@ static void mousevsc_on_receive_device_info(struct mousevsc_dev *input_device,
 	if (desc->bLength == 0)
 		goto cleanup;
 
+	/* The pointer is not NULL when we resume from hibernation */
+	if (input_device->hid_desc != NULL)
+		kfree(input_device->hid_desc);
 	input_device->hid_desc = kmemdup(desc, desc->bLength, GFP_ATOMIC);
 
 	if (!input_device->hid_desc)
@@ -203,6 +206,9 @@ static void mousevsc_on_receive_device_info(struct mousevsc_dev *input_device,
 		goto cleanup;
 	}
 
+	/* The pointer is not NULL when we resume from hibernation */
+	if (input_device->report_desc != NULL)
+		kfree(input_device->report_desc);
 	input_device->report_desc = kzalloc(input_device->report_desc_size,
 					  GFP_ATOMIC);
 
@@ -342,6 +348,8 @@ static int mousevsc_connect_to_vsp(struct hv_device *device)
 	struct mousevsc_prt_msg *request;
 	struct mousevsc_prt_msg *response;
 
+	reinit_completion(&input_dev->wait_event);
+
 	request = &input_dev->protocol_req;
 	memset(request, 0, sizeof(struct mousevsc_prt_msg));
 
@@ -541,6 +549,30 @@ static int mousevsc_remove(struct hv_device *dev)
 	return 0;
 }
 
+static int mousevsc_suspend(struct hv_device *dev)
+{
+	vmbus_close(dev->channel);
+
+	return 0;
+}
+
+static int mousevsc_resume(struct hv_device *dev)
+{
+	int ret;
+
+	ret = vmbus_open(dev->channel,
+			 INPUTVSC_SEND_RING_BUFFER_SIZE,
+			 INPUTVSC_RECV_RING_BUFFER_SIZE,
+			 NULL, 0,
+			 mousevsc_on_channel_callback,
+			 dev);
+	if (ret)
+		return ret;
+
+	ret = mousevsc_connect_to_vsp(dev);
+	return ret;
+}
+
 static const struct hv_vmbus_device_id id_table[] = {
 	/* Mouse guid */
 	{ HV_MOUSE_GUID, },
@@ -554,6 +586,8 @@ static struct  hv_driver mousevsc_drv = {
 	.id_table = id_table,
 	.probe = mousevsc_probe,
 	.remove = mousevsc_remove,
+	.suspend = mousevsc_suspend,
+	.resume = mousevsc_resume,
 	.driver = {
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
-- 
2.19.1