HID: nintendo: add rumble support

This patch adds support for controller rumble.

The ff_effect weak magnitude is associated with the pro controller's
right motor (or with a right joy-con). The strong magnitude is
associated with the pro's left motor (or a left joy-con).

The rumble data is sent periodically (currently configured for every 50
milliseconds). If the controller receives no rumble data for too long a
time period, it will stop vibrating. The data is also sent every time
joycon_set_rumble is called to avoid latency of up to 50ms.

Because the rumble subcommands are sent in a deferred workqueue (they
can't be sent in the play_effect function due to the hid send sleeping),
the effects are queued. This ensures that no rumble effect is missed due
to them arriving in too quick of succession.
Signed-off-by: Daniel J. Ogorchock <djogorchock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/Kconfig

@@ -745,6 +745,16 @@ config HID_NINTENDO
 	To compile this driver as a module, choose M here: the
 	module will be called hid-nintendo.
 
+config NINTENDO_FF
+	bool "Nintendo Switch controller force feedback support"
+	depends on HID_NINTENDO
+	select INPUT_FF_MEMLESS
+	help
+	Say Y here if you have a Nintendo Switch controller and want to enable
+	force feedback support for it. This works for both joy-cons and the pro
+	controller. For the pro controller, both rumble motors can be controlled
+	individually.
+
 config HID_NTI
 	tristate "NTI keyboard adapters"
 	help