Input: imx_sc_key - use devm_add_action_or_reset() to handle all cleanups

Use devm_add_action_or_reset() to handle all cleanups of failure in
.probe and .remove, then .remove callback can be dropped.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1584082751-17047-1-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: imx_sc_key - only take the valid data from SCU firmware as key state

When reading key state from SCU, the response data from SCU firmware
is 4 bytes due to MU message protocol, but ONLY the first byte is the
key state, other 3 bytes could be some dirty data, so we should ONLY
take the first byte as key state to avoid reporting incorrect state.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Fixes: 688f1dfb69b4 ("Input: keyboard - imx_sc: Add i.MX system controller key support")
Link: https://lore.kernel.org/r/1576202909-1661-1-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: imx_sc_key - correct SCU message structure to avoid stack corruption

The SCU message's data field used for receiving response data from SCU
should be 32-bit width, as SCU will send back 32-bit width data.

This solves kernel panic when CONFIG_CC_HAVE_STACKPROTECTOR_SYSREG is
enabled.

[ 1.950768] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted
[ 1.980607] Workqueue: events imx_sc_check_for_events
[ 1.985657] Call trace:
[ 1.988104] dump_backtrace+0x0/0x140
[ 1.991768] show_stack+0x14/0x20
[ 1.995090] dump_stack+0xb4/0xf8
[ 1.998407] panic+0x158/0x324
[ 2.001463] print_tainted+0x0/0xa8
[ 2.004950] imx_sc_check_for_events+0x18c/0x190
[ 2.009569] process_one_work+0x198/0x320
[ 2.013579] worker_thread+0x48/0x420
[ 2.017252] kthread+0xf0/0x120
[ 2.020394] ret_from_fork+0x10/0x18
[ 2.023977] SMP: stopping secondary CPUs
[ 2.027901] Kernel Offset: disabled
[ 2.031391] CPU features: 0x0002,2100600c
[ 2.035401] Memory Limit: none

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Fixes: 688f1dfb69b4 ("Input: keyboard - imx_sc: Add i.MX system controller key support")
Link: https://lore.kernel.org/r/1573730499-2224-1-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: keyboard - imx_sc: Add i.MX system controller key support

i.MX8QXP is an ARMv8 SoC which has a Cortex-M4 system controller
inside, the system controller is in charge of controlling power,
clock and scu key etc..

Adds i.MX system controller key driver support, Linux kernel has
to communicate with system controller via MU (message unit) IPC
to get scu key's status.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1570412509-7893-2-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>