[PATCH 1/3] HID: Add shutdown callback for device drivers

[Mario Limonciello <mario.limonciello@amd.com>]

HID device drivers can receive suspend and resume notifications through
callbacks forwarded by their transport driver.  There is no corresponding
way to perform device-specific work during an orderly system shutdown.

Add a shutdown callback to struct hid_driver and dispatch it from the HID
bus shutdown operation.  This allows a HID device driver to communicate
with hardware before its transport is shut down.

Assisted-by: LLM
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/hid/hid-core.c | 13 +++++++++++++
 include/linux/hid.h    |  2 ++
 2 files changed, 15 insertions(+)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index a3ff0514f9cdf..7c8c1aa1f09c3 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2738,6 +2738,18 @@ static int hid_bus_match(struct device *dev, const struct device_driver *drv)
 	return hid_match_device(hdev, hdrv) != NULL;
 }
 
+static void hid_bus_shutdown(struct device *dev)
+{
+	struct hid_driver *hdrv;
+
+	if (!dev->driver)
+		return;
+
+	hdrv = to_hid_driver(dev->driver);
+	if (hdrv->shutdown)
+		hdrv->shutdown(to_hid_device(dev));
+}
+
 /**
  * hid_compare_device_paths - check if both devices share the same path
  * @hdev_a: hid device
@@ -3012,6 +3024,7 @@ const struct bus_type hid_bus_type = {
 	.match		= hid_bus_match,
 	.probe		= hid_device_probe,
 	.remove		= hid_device_remove,
+	.shutdown	= hid_bus_shutdown,
 	.uevent		= hid_uevent,
 };
 EXPORT_SYMBOL(hid_bus_type);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 8d17b741638c9..ddf57779bb3ef 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -861,6 +861,7 @@ struct hid_usage_id {
  * @suspend: invoked on suspend (NULL means nop)
  * @resume: invoked on resume if device was not reset (NULL means nop)
  * @reset_resume: invoked on resume if device was reset (NULL means nop)
+ * @shutdown: invoked on system shutdown (NULL means nop)
  * @on_hid_hw_open: invoked when hid core opens first instance (NULL means nop)
  * @on_hid_hw_close: invoked when hid core closes last instance (NULL means nop)
  *
@@ -924,6 +925,7 @@ struct hid_driver {
 	int (*suspend)(struct hid_device *hdev, pm_message_t message);
 	int (*resume)(struct hid_device *hdev);
 	int (*reset_resume)(struct hid_device *hdev);
+	void (*shutdown)(struct hid_device *hdev);
 	void (*on_hid_hw_open)(struct hid_device *hdev);
 	void (*on_hid_hw_close)(struct hid_device *hdev);
 
-- 
2.43.0