[PATCH] HID: Add driver for acer keybard with broken rdesc

[linux@simon-woerner.de]

From: Simon Wörner <mail@simon-woerner.de>

HID: Add driver for acer keybard with broken rdesc

Signed-off-by: Simon Wörner <mail@simon-woerner.de>
---
 drivers/hid/Kconfig    |  6 +++++
 drivers/hid/Makefile   |  1 +
 drivers/hid/hid-acer.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/hid/hid-ids.h  |  3 +++
 4 files changed, 80 insertions(+)
 create mode 100644 drivers/hid/hid-acer.c

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index dfdc269..f3ae543 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -98,6 +98,12 @@ config HID_A4TECH
 	---help---
 	Support for A4 tech X5 and WOP-35 / Trust 450L mice.
 
+config HID_ACER
+        tristate "Acer keyboard support"
+        depends on HID
+        ---help---
+        Support for acer keyboard with invalid rdesc.
+
 config HID_ACRUX
 	tristate "ACRUX game controller support"
 	depends on HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index debd15b..143602b 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -34,6 +34,7 @@ ifdef CONFIG_DEBUG_FS
 endif
 
 obj-$(CONFIG_HID_A4TECH)	+= hid-a4tech.o
+obj-$(CONFIG_HID_ACER)		+= hid-acer.o
 obj-$(CONFIG_HID_ACRUX)		+= hid-axff.o
 obj-$(CONFIG_HID_APPLE)		+= hid-apple.o
 obj-$(CONFIG_HID_APPLEIR)	+= hid-appleir.o
diff --git a/drivers/hid/hid-acer.c b/drivers/hid/hid-acer.c
new file mode 100644
index 0000000..b3ccd8b
--- /dev/null
+++ b/drivers/hid/hid-acer.c
@@ -0,0 +1,70 @@
+/*
+ *  HID driver for acer devices
+ *
+ *  Copyright (c) 2015 Simon Wörner
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/* Acer keyboards e.g. in Acer SW5-012 use synaptics touchpad USB ID (06cb:2968)
+ * and have the following issue:
+ * - The report descriptor specifies an excessively large number of usages
+ *   and logical max (2^16), which is more than HID_MAX_USAGES. This prevents
+ *   proper parsing of the report descriptor.
+ *
+ * The byte replace in the descriptor below fixes the size.
+ */
+
+#define ACER_KBD_RDESC_ORIG_SIZE	188
+#define ACER_KBD_RDESC_CHECK_POS	(150 * sizeof(__u8))
+#define ACER_KBD_RDESC_CHECK_DATA	0x2AFFFF150026FFFF
+#define ACER_KBD_RDESC_FIX_POS1		152
+#define ACER_KBD_RDESC_FIX_POS2		157
+
+static __u8 *acer_kbd_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	/* check for invalid descriptor */
+	if (*rsize == ACER_KBD_RDESC_ORIG_SIZE) {
+		__u64 check = be64_to_cpu(*(__be64 *)(rdesc + ACER_KBD_RDESC_CHECK_POS));
+
+		/* check for invalid max usages and logical 0xFFFF (2^16) */
+		if (check == ACER_KBD_RDESC_CHECK_DATA) {
+			hid_info(hdev, "fixing up acer keybaord report descriptor\n");
+
+			/* fix max values with 0xFF00 (2^8) */
+			rdesc[ACER_KBD_RDESC_FIX_POS1] = 0x00;
+			rdesc[ACER_KBD_RDESC_FIX_POS2] = 0x00;
+		}
+	}
+
+	return rdesc;
+}
+
+static const struct hid_device_id acer_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ACER_SYNAPTICS,
+		USB_VENDOR_ID_ACER_SYNAPTICS_TP) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, acer_devices);
+
+static struct hid_driver acer_driver = {
+	.name = "acer",
+	.id_table = acer_devices,
+	.report_fixup = acer_kbd_report_fixup,
+};
+module_hid_driver(acer_driver);
+
+MODULE_AUTHOR("Simon Wörner");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 9243359..5d9482b 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -35,6 +35,9 @@
 #define USB_DEVICE_ID_ACECAD_FLAIR	0x0004
 #define USB_DEVICE_ID_ACECAD_302	0x0008
 
+#define USB_VENDOR_ID_ACER_SYNAPTICS	0x06cb
+#define USB_VENDOR_ID_ACER_SYNAPTICS_TP 0x2968
+
 #define USB_VENDOR_ID_ACRUX		0x1a34
 
 #define USB_VENDOR_ID_ACTIONSTAR	0x2101
-- 
2.2.2

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