linux-kernel - [PATCH HID v3 8/9] HID: add per device quirk to force bind to hid-generic

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Message-Id: <20241001-hid-bpf-hid-generic-v3-8-2ef1019468df@kernel.org>
Date: Tue, 01 Oct 2024 16:30:12 +0200
From: Benjamin Tissoires <bentiss@...nel.org>
To: Jiri Kosina <jikos@...nel.org>, 
 Peter Hutterer <peter.hutterer@...-t.net>, Vicki Pfau <vi@...rift.com>, 
 Shuah Khan <shuah@...nel.org>
Cc: linux-input@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, bpf@...r.kernel.org, 
 Benjamin Tissoires <bentiss@...nel.org>
Subject: [PATCH HID v3 8/9] HID: add per device quirk to force bind to
 hid-generic

We already have the possibility to force not binding to hid-generic and
rely on a dedicated driver, but we couldn't do the other way around.

This is useful for BPF programs where we are fixing the report descriptor
and the events, but want to avoid a specialized driver to come after BPF
which would unwind everything that is done there.

Reviewed-by: Peter Hutterer <peter.hutterer@...-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>

---

no changes in v3

changes in v2:
- rely on hdev->quirks for that instead of a new struct for hid_driver
---
 drivers/hid/hid-core.c    | 5 +++--
 drivers/hid/hid-generic.c | 3 +++
 include/linux/hid.h       | 2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 8e879937e956..f1c23b21e96a 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2698,9 +2698,10 @@ static bool hid_check_device_match(struct hid_device *hdev,
 	/*
 	 * hid-generic implements .match(), so we must be dealing with a
 	 * different HID driver here, and can simply check if
-	 * hid_ignore_special_drivers is set or not.
+	 * hid_ignore_special_drivers or HID_QUIRK_IGNORE_SPECIAL_DRIVER
+	 * are set or not.
 	 */
-	return !hid_ignore_special_drivers;
+	return !hid_ignore_special_drivers && !(hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER);
 }
 
 static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
diff --git a/drivers/hid/hid-generic.c b/drivers/hid/hid-generic.c
index f9db991d3c5a..88882c1bfffe 100644
--- a/drivers/hid/hid-generic.c
+++ b/drivers/hid/hid-generic.c
@@ -40,6 +40,9 @@ static bool hid_generic_match(struct hid_device *hdev,
 	if (ignore_special_driver)
 		return true;
 
+	if (hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER)
+		return true;
+
 	if (hdev->quirks & HID_QUIRK_HAVE_SPECIAL_DRIVER)
 		return false;
 
diff --git a/include/linux/hid.h b/include/linux/hid.h
index ff58b5ceb62e..63330d623335 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -359,6 +359,7 @@ struct hid_item {
  * | @HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP:
  * | @HID_QUIRK_HAVE_SPECIAL_DRIVER:
  * | @HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE:
+ * | @HID_QUIRK_IGNORE_SPECIAL_DRIVER
  * | @HID_QUIRK_FULLSPEED_INTERVAL:
  * | @HID_QUIRK_NO_INIT_REPORTS:
  * | @HID_QUIRK_NO_IGNORE:
@@ -384,6 +385,7 @@ struct hid_item {
 #define HID_QUIRK_HAVE_SPECIAL_DRIVER		BIT(19)
 #define HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE	BIT(20)
 #define HID_QUIRK_NOINVERT			BIT(21)
+#define HID_QUIRK_IGNORE_SPECIAL_DRIVER		BIT(22)
 #define HID_QUIRK_FULLSPEED_INTERVAL		BIT(28)
 #define HID_QUIRK_NO_INIT_REPORTS		BIT(29)
 #define HID_QUIRK_NO_IGNORE			BIT(30)

-- 
2.46.0