input-support: add a package for input device handling

The evdev character devices come out 0600 root:root, so a display server
or any other process reading keyboards and pointers runs as root.

Add an input-support package which allocates the input group and puts the
input nodes into it, and make the evdev and joydev modules depend on it.
The one device profile that ships evdev lists the package directly.
kmod-input-core stays ungated: it carries no device node of its own, and
most drivers built on it deliver their events to in-kernel consumers such
as the keyboard and button handlers.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/kernel/linux/modules/input.mk

@@ -104,7 +104,7 @@ $(eval $(call KernelPackage,input-core))
 define KernelPackage/input-evdev
   SUBMENU:=$(INPUT_MODULES_MENU)
   TITLE:=Input event device
-  DEPENDS:=+kmod-input-core
+  DEPENDS:=input-support +kmod-input-core
   KCONFIG:=CONFIG_INPUT_EVDEV
   FILES:=$(LINUX_DIR)/drivers/input/evdev.ko
   AUTOLOAD:=$(call AutoLoad,60,evdev)
@@ -196,7 +196,7 @@ $(eval $(call KernelPackage,input-matrix-keypad))
 define KernelPackage/input-joydev
   SUBMENU:=$(INPUT_MODULES_MENU)
   TITLE:=Joystick device support
-  DEPENDS:=+kmod-input-core
+  DEPENDS:=input-support +kmod-input-core
   KCONFIG:=CONFIG_INPUT_JOYDEV
   FILES:=$(LINUX_DIR)/drivers/input/joydev.ko
   AUTOLOAD:=$(call AutoProbe,joydev)

package/system/hardware-support/Makefile

@@ -78,6 +78,23 @@ define Package/accel-support/install
 	$(call InstallFragment,$(1),35-accel.json)
 endef
 
+define Package/input-support
+  $(call Package/hardware-support/Default)
+  TITLE:=Input device support
+  USERID:=:input=41
+endef
+
+define Package/input-support/description
+ Feature gate for input devices. Allocates the input group and installs
+ the hotplug rules which put the evdev character devices into it. Kernel
+ modules exposing input devices and userspace using the group depend on
+ this package.
+endef
+
+define Package/input-support/install
+	$(call InstallFragment,$(1),40-input.json)
+endef
+
 define Build/Prepare
 endef
 
@@ -90,3 +107,4 @@ endef
 $(eval $(call BuildPackage,audio-support))
 $(eval $(call BuildPackage,video-support))
 $(eval $(call BuildPackage,accel-support))
+$(eval $(call BuildPackage,input-support))

package/system/hardware-support/files/40-input.json

@@ -0,0 +1,6 @@
+[
+	[ "if",
+		[ "eq", "SUBSYSTEM", "input" ],
+		[ "makedev", "/dev/%DEVNAME%", "0660", "input" ]
+	]
+]

target/linux/ramips/image/mt76x8.mk

@@ -737,7 +737,8 @@ define Device/qding_qc202
   IMAGE_SIZE := 7872k
   DEVICE_VENDOR := Qding
   DEVICE_MODEL := QC202
-  DEVICE_PACKAGES := kmod-i2c-mt7628 kmod-gpio-beeper kmod-input-matrix-keypad kmod-input-evdev uboot-envtools
+  DEVICE_PACKAGES := kmod-i2c-mt7628 kmod-gpio-beeper kmod-input-matrix-keypad kmod-input-evdev \
+	input-support uboot-envtools
   IMAGES += factory.bin
   IMAGE/factory.bin := $$(sysupgrade_bin) | qding-header qc202
 endef