Commit 76cdc083 authored by Alberto Panizzo's avatar Alberto Panizzo Committed by Dmitry Torokhov

Input: add imx-keypad driver to support the IMX Keypad Port

The IMX family of Application Processors is shipped with a Keypad Port
supported by this driver.

The peripheral can control up to an 8x8 matrix key pad where all the
scanning is done via software.  The hardware provides two interrupts:
one for key presses (KDI) and one for all key releases (KRI). There is
also a simple circuit for glitch reduction (said for synchronization)
made by two series of 3 D-latches clocked by the keypad-clock that
stabilize the interrupts sources. KDI and KRI are fired only if the
respective conditions are maintained for at last 4 keypad-clock cycle.

Since those circuits are poor for a correct debounce process (the
keypad-clock frequency is 32K and bounces longer than 94us are not
masked) the driver, when an interrupt arrives, samples the matrix
with a period of 10ms until the readins are stable for
IMX_KEYPAD_SCANS_FOR_STABILITY times (currently set at 3). After
getting stable result appropriate events are sent through the input
stack.

If some keys are maintained pressed, the driver continues to scan
the matrix with a longer period (60ms) to catch possible multiple
key presses without overloading the cpu. This process ends when all
keys are released.

This driver is tested to build in kernel or as a module and follow
the specification of Freescale Application processors:
i.MX25 i.MX27 i.MX31 i.MX35 i.MX51 especially tested on i.MX31.
Signed-off-by: default avatarAlberto Panizzo <maramaopercheseimorto@gmail.com>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent 429722e1
......@@ -292,6 +292,15 @@ config KEYBOARD_MAX7359
To compile this driver as a module, choose M here: the
module will be called max7359_keypad.
config KEYBOARD_IMX
tristate "IMX keypad support"
depends on ARCH_MXC
help
Enable support for IMX keypad port.
To compile this driver as a module, choose M here: the
module will be called imx_keypad.
config KEYBOARD_NEWTON
tristate "Newton keyboard"
select SERIO
......
......@@ -17,6 +17,7 @@ obj-$(CONFIG_KEYBOARD_EP93XX) += ep93xx_keypad.o
obj-$(CONFIG_KEYBOARD_GPIO) += gpio_keys.o
obj-$(CONFIG_KEYBOARD_HIL) += hil_kbd.o
obj-$(CONFIG_KEYBOARD_HIL_OLD) += hilkbd.o
obj-$(CONFIG_KEYBOARD_IMX) += imx_keypad.o
obj-$(CONFIG_KEYBOARD_HP6XX) += jornada680_kbd.o
obj-$(CONFIG_KEYBOARD_HP7XX) += jornada720_kbd.o
obj-$(CONFIG_KEYBOARD_LKKBD) += lkkbd.o
......
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