powerpc/fsl: fix compiler warning in fsl_wakeup_sys_init()

Commit c93bd175414a ("powerpc/fsl: move to use bus_get_dev_root()")
changed to use bus_get_dev_root() but didn't consider that the function
can fail and return an uninitialized value of ret (hint, the function
can never fail, but the compiler doesn't know that.)

Fix this up by setting ret to -EINVAL just in case something really goes
wrong with the call to bus_get_dev_root().

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linuxppc-dev@lists.ozlabs.org
Fixes: c93bd175414a ("powerpc/fsl: move to use bus_get_dev_root()")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303280045.4oaaezcn-lkp@intel.com/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230327181606.1424846-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/fsl: move to use bus_get_dev_root()

Direct access to the struct bus_type dev_root pointer is going away soon
so replace that with a call to bus_get_dev_root() instead, which is what
it is there for.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230313182918.1312597-15-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/mpic_timer: avoid struct timeval

In an effort to remove all instances of 'struct timeval'
from the kernel, I'm changing the powerpc mpic_timer interface
to use plain seconds instead. There is only one user of this
interface, and that doesn't use the microseconds portion, so
the code gets noticeably simpler in the process.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/fsl: add MPIC timer wakeup support

The driver provides a way to wake up the system by the MPIC timer.

For example,
echo 5 > /sys/devices/system/mpic/timer_wakeup
echo standby > /sys/power/state

After 5 seconds the MPIC timer will generate an interrupt to wake up
the system.

Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Signed-off-by: Zhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>