linux-kernel - [PATCH for-5.19/uclogic 4/5] HID: uclogic: Support disabling pen usage

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Date:   Thu, 21 Apr 2022 19:50:51 +0200
From:   José Expósito <jose.exposito89@...il.com>
To:     jikos@...nel.org
Cc:     benjamin.tissoires@...hat.com, spbnick@...il.com,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        José Expósito <jose.exposito89@...il.com>
Subject: [PATCH for-5.19/uclogic 4/5] HID: uclogic: Support disabling pen usage

From: Nikolai Kondrashov <spbnick@...il.com>

Restore the ability to disable pen usage in hid-uclogic to support e.g.
keyboard interfaces which also have pen usages for some reason, but
which we don't want to rewrite report descriptors for.

Signed-off-by: Nikolai Kondrashov <spbnick@...il.com>
Signed-off-by: José Expósito <jose.exposito89@...il.com>
---
 drivers/hid/hid-uclogic-core.c   | 19 +++++++++++++++++++
 drivers/hid/hid-uclogic-params.h |  7 +++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/hid/hid-uclogic-core.c b/drivers/hid/hid-uclogic-core.c
index 627f1d0c52f2..8ef3d1830052 100644
--- a/drivers/hid/hid-uclogic-core.c
+++ b/drivers/hid/hid-uclogic-core.c
@@ -81,6 +81,24 @@ static __u8 *uclogic_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 	return rdesc;
 }
 
+static int uclogic_input_mapping(struct hid_device *hdev,
+				 struct hid_input *hi,
+				 struct hid_field *field,
+				 struct hid_usage *usage,
+				 unsigned long **bit,
+				 int *max)
+{
+	struct uclogic_drvdata *drvdata = hid_get_drvdata(hdev);
+	struct uclogic_params *params = &drvdata->params;
+
+	/* Discard invalid pen usages */
+	if (params->pen.usage_invalid && (field->application == HID_DG_PEN))
+		return -1;
+
+	/* Let hid-core decide what to do */
+	return 0;
+}
+
 static int uclogic_input_configured(struct hid_device *hdev,
 		struct hid_input *hi)
 {
@@ -515,6 +533,7 @@ static struct hid_driver uclogic_driver = {
 	.remove = uclogic_remove,
 	.report_fixup = uclogic_report_fixup,
 	.raw_event = uclogic_raw_event,
+	.input_mapping = uclogic_input_mapping,
 	.input_configured = uclogic_input_configured,
 #ifdef CONFIG_PM
 	.resume	          = uclogic_resume,
diff --git a/drivers/hid/hid-uclogic-params.h b/drivers/hid/hid-uclogic-params.h
index fa75efba3130..fb2001018c46 100644
--- a/drivers/hid/hid-uclogic-params.h
+++ b/drivers/hid/hid-uclogic-params.h
@@ -61,6 +61,11 @@ struct uclogic_params_pen_subreport {
  * Noop (preserving functionality) when filled with zeroes.
  */
 struct uclogic_params_pen {
+	/*
+	 * True if pen usage is invalid for this interface and should be
+	 * ignored, false otherwise.
+	 */
+	bool usage_invalid;
 	/*
 	 * Pointer to report descriptor part describing the pen inputs.
 	 * Allocated with kmalloc. NULL if the part is not specified.
@@ -214,6 +219,7 @@ extern int uclogic_params_init(struct uclogic_params *params,
 	".desc_ptr = %p\n"                  \
 	".desc_size = %u\n"                 \
 	".pen = {\n"                        \
+	"\t.usage_invalid = %s\n"           \
 	"\t.desc_ptr = %p\n"                \
 	"\t.desc_size = %u\n"               \
 	"\t.id = %u\n"                      \
@@ -270,6 +276,7 @@ extern int uclogic_params_init(struct uclogic_params *params,
 	((_params)->invalid ? "true" : "false"),                    \
 	(_params)->desc_ptr,                                        \
 	(_params)->desc_size,                                       \
+	((_params)->pen.usage_invalid ? "true" : "false"),          \
 	(_params)->pen.desc_ptr,                                    \
 	(_params)->pen.desc_size,                                   \
 	(_params)->pen.id,                                          \
-- 
2.25.1