[PATCH] HID: dell: Add hid-dell driver

[Hans de Goede <hdegoede@redhat.com>]

The keyboard-dock and the keyboard-cover available with the Dell
Venue 11 Pro 2-in-1 devices use a custom HID usage code for their
wireless-lan toggle button.

This commit adds a specialised hid driver for this (both devices use the
same VID:PID). Since these devices also contain a synaptics RMI touchpad
on the same USB-device the hid_have_special_driver table cannot be used,
instead this commit adds a new HID_GROUP_DELL group and makes
hid_scan_report set hid_device->group to this for the non touchpad
interfaces of the shared USB-device.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/hid/Kconfig    |  7 +++++++
 drivers/hid/Makefile   |  1 +
 drivers/hid/hid-core.c |  7 +++++++
 drivers/hid/hid-dell.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/hid/hid-ids.h  |  1 +
 include/linux/hid.h    |  1 +
 6 files changed, 65 insertions(+)
 create mode 100644 drivers/hid/hid-dell.c

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 8c54cb8..08bce92 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -229,6 +229,13 @@ config HID_CYPRESS
 	---help---
 	Support for cypress mouse and barcode readers.
 
+config HID_DELL
+	tristate "Dell 2-in-1 keyboard-dock / type-cover"
+	depends on HID
+	default !EXPERT
+	---help---
+	Support for extra keys on Dell 2-in-1 keyboard-docks / type-covers.
+
 config HID_DRAGONRISE
 	tristate "DragonRise Inc. game controller"
 	depends on HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 4d111f2..b02a943 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_HID_CMEDIA)	+= hid-cmedia.o
 obj-$(CONFIG_HID_CORSAIR)	+= hid-corsair.o
 obj-$(CONFIG_HID_CP2112)	+= hid-cp2112.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
+obj-$(CONFIG_HID_DELL)		+= hid-dell.o
 obj-$(CONFIG_HID_DRAGONRISE)	+= hid-dr.o
 obj-$(CONFIG_HID_EMS_FF)	+= hid-emsff.o
 obj-$(CONFIG_HID_ELECOM)	+= hid-elecom.o
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 63ec199..7c7bec43 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -829,6 +829,13 @@ static int hid_scan_report(struct hid_device *hid)
 				 */
 				if (IS_ENABLED(CONFIG_HID_RMI))
 					hid->group = HID_GROUP_RMI;
+
+		if (hid->group == HID_GROUP_GENERIC &&
+		    hid->product == USB_DEVICE_ID_SYNAPTICS_DELL_KBD_DOCK)
+			/* hid-dell should take care of this device */
+			if (IS_ENABLED(CONFIG_HID_DELL))
+				hid->group = HID_GROUP_DELL;
+
 		break;
 	}
 
diff --git a/drivers/hid/hid-dell.c b/drivers/hid/hid-dell.c
new file mode 100644
index 0000000..4f7a7f8
--- /dev/null
+++ b/drivers/hid/hid-dell.c
@@ -0,0 +1,48 @@
+/*
+ * HID driver for some Dell "special" devices
+ * Copyright (c) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define DELL_WIRELESS_TOGGLE_HID	0x100c6
+
+static int dell_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if (usage->hid == DELL_WIRELESS_TOGGLE_HID) {
+		hid_map_usage_clear(hi, usage, bit, max, EV_KEY, KEY_WLAN);
+		/* Only press events get reported, simulate release */
+		field->flags |= HID_MAIN_ITEM_RELATIVE;
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id dell_devices[] = {
+	/* Only bind to HID_GROUP_DELL, let RMI deal with the touchpad. */
+	{ HID_DEVICE(BUS_USB, HID_GROUP_DELL, USB_VENDOR_ID_SYNAPTICS,
+		     USB_DEVICE_ID_SYNAPTICS_DELL_KBD_DOCK), },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, dell_devices);
+
+static struct hid_driver dell_driver = {
+	.name = "dell",
+	.id_table = dell_devices,
+	.input_mapping = dell_input_mapping,
+};
+module_hid_driver(dell_driver);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 4e2648c..9c3eba7 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -968,6 +968,7 @@
 #define USB_DEVICE_ID_SYNAPTICS_LTS2	0x1d10
 #define USB_DEVICE_ID_SYNAPTICS_HD	0x0ac3
 #define USB_DEVICE_ID_SYNAPTICS_QUAD_HD	0x1ac3
+#define USB_DEVICE_ID_SYNAPTICS_DELL_KBD_DOCK	0x2819
 #define USB_DEVICE_ID_SYNAPTICS_TP_V103	0x5710
 
 #define USB_VENDOR_ID_TEXAS_INSTRUMENTS	0x2047
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 28f38e2b8..223a61f 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -349,6 +349,7 @@ struct hid_item {
 #define HID_GROUP_RMI				0x0100
 #define HID_GROUP_WACOM				0x0101
 #define HID_GROUP_LOGITECH_DJ_DEVICE		0x0102
+#define HID_GROUP_DELL				0x0103
 
 /*
  * This is the global environment of the parser. This information is
-- 
2.9.3