HID: Add Apple DockChannel HID transport driver

Apple M2 devices have an MTP coprocessor embedded in the SoC that
handles HID for the integrated touchpad/keyboard, and communicates
over the DockChannel interface. This driver implements this new
interface.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

drivers/hid/Kconfig

@@ -1437,4 +1437,6 @@ source "drivers/hid/usbhid/Kconfig"
 
 source "drivers/hid/spi-hid/Kconfig"
 
+source "drivers/hid/dockchannel-hid/Kconfig"
+
 endif # HID_SUPPORT

drivers/hid/Makefile

@@ -172,8 +172,12 @@ obj-$(CONFIG_INTEL_ISH_HID)	+= intel-ish-hid/
 
 obj-$(CONFIG_AMD_SFH_HID)       += amd-sfh-hid/
 
+obj-$(CONFIG_HID_DOCKCHANNEL)   += dockchannel-hid/
+
 obj-$(CONFIG_SPI_HID_APPLE_CORE)	+= spi-hid/
 
+obj-$(CONFIG_HID_DOCKCHANNEL)   += dockchannel-hid/
+
 obj-$(CONFIG_SURFACE_HID_CORE)  += surface-hid/
 
 obj-$(CONFIG_INTEL_THC_HID)     += intel-thc-hid/

drivers/hid/dockchannel-hid/Kconfig

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0-only OR MIT
+menu "DockChannel HID support"
+	depends on APPLE_DOCKCHANNEL
+
+config HID_DOCKCHANNEL
+	tristate "HID over DockChannel transport layer for Apple Silicon SoCs"
+	depends on APPLE_DOCKCHANNEL && INPUT && OF && HID
+	help
+	  Say Y here if you use an M2 or later Apple Silicon based laptop.
+	  The keyboard and touchpad are HID based devices connected via the
+	  proprietary DockChannel interface.
+
+endmenu

drivers/hid/dockchannel-hid/Makefile

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only OR MIT
+#
+# Makefile for DockChannel HID transport drivers
+#
+
+obj-$(CONFIG_HID_DOCKCHANNEL)	+= dockchannel-hid.o