ARM: imx: add smp support for imx7d

Add SMP support for i.MX7D, including CPU hotplug support, for
systems where TFA is not present.

The motivation for bringing up the second i.MX7D core inside the kernel
is that legacy vendor bootloaders usually do not implement PSCI support.

This is a significant blocker for systems in the field that are running old
bootloader versions to upgrade to a modern mainline kernel version, as only
one CPU of the i.MX7D would be brought up.

Bring up the second i.MX7D core inside the kernel to make the migration
path to mainline kernel easier for the existing iMX7D users.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Arulpandiyan Vadivel <arulpandiyan_vadivel@mentor.com> # Fix merge conflicts
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Marek Vasut <marex@denx.de> # heavy cleanup
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

ARM: imx: use generic function to exit coherency

The common ARM architecture code provides a generic function to exit
coherency called v7_exit_coherency_flush(). Replace the machine
specific implementation using the generic function.

Tested on a i.MX 6Dual by hotplugging the secondary CPU under load
through sysfs several 1000 times.

Tested-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 159

Based on 1 normalized pattern(s):

the code contained herein is licensed under the gnu general public
license you may obtain a copy of the gnu general public license
version 2 or later at the following locations http www opensource
org licenses gpl license html http www gnu org copyleft gpl html

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 161 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.383790741@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ARM: imx: do not return from imx_cpu_die() call

When imx_cpu_die() is being called, the cpu should never return from the
call but just in WFI and wait for hardware to take it down. So let's
do cpu_do_idle() repeatly in the call. Doing this help improve the
relibility of hotplug operation.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

ARM: imx: compile fix for hotplug.c

Commit bca7a5a (ARM: cpu hotplug: remove majority of cache flushing
from platforms) removes include of <asm/cacheflush.h> and hence
discovers a few indirect inclusion and declaration problems as below.

CC arch/arm/mach-imx/hotplug.o
In file included from arch/arm/mach-imx/hotplug.c:16:0:
arch/arm/mach-imx/common.h:100:29: warning: ‘struct pt_regs’ declared inside parameter list [enabled by default]
arch/arm/mach-imx/common.h:100:29: warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]
arch/arm/mach-imx/common.h:101:29: warning: ‘struct pt_regs’ declared inside parameter list [enabled by default]
arch/arm/mach-imx/hotplug.c: In function ‘imx_cpu_die’:
arch/arm/mach-imx/hotplug.c:53:2: error: implicit declaration of function ‘cpu_do_idle’ [-Werror=implicit-function-declaration]
arch/arm/mach-imx/hotplug.c: In function ‘imx_cpu_kill’:
arch/arm/mach-imx/hotplug.c:58:26: error: ‘jiffies’ undeclared (first use in this function)
arch/arm/mach-imx/hotplug.c:58:26: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/mach-imx/hotplug.c:58:2: error: implicit declaration of function ‘msecs_to_jiffies’ [-Werror=implicit-function-declaration]
arch/arm/mach-imx/hotplug.c:61:3: error: implicit declaration of function ‘time_after’ [-Werror=implicit-function-declaration]

Fix them by adding the needed inclusion and declaration.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Olof Johansson <olof@lixom.net>

ARM: cpu hotplug: remove majority of cache flushing from platforms

Remove the majority of cache flushing calls from the individual platform
files. This is now handled by the core code.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: imx: fix sync issue between imx_cpu_die and imx_cpu_kill

There is a sync issue with hotplug operation. It's possible that when
imx_cpu_kill gets running on primary core, the imx_cpu_die execution
on the core which is to be killed hasn't been finished yet. The problem
will very likely be hit when running suspend without no_console_suspend
setting on kernel cmdline.

It uses cpu jumping argument register to sync imx_cpu_die and
imx_cpu_kill. The register will be set in imx_cpu_die and imx_cpu_kill
will wait for the register being cleared to actually kill the cpu.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: <stable@vger.kernel.org>

ARM: imx: disable cpu in .cpu_kill hook

It's buggy to disable the cpu that is being hot-unplugged in .cpu_die
hook which runs on the cpu itself. Instead, it should be done in
.cpu_kill which runs on the thread (another cpu) that asks for shutting
down the cpu. Move imx_enable_cpu(cpu, false) call into .cpu_kill
hook, and leave the cpu to be hot-unplugged in WFI within .cpu_die,
so that we can get a more stable cpu hot-plug operation.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

ARM: imx: include common.h rather than mach/common.h

Rename mach-imx/include/mach/common.h to mach-imx/common.h and update
all users to include common.h rather than mach/common.h.

It also removes an unneeded inclusion to common.h in
mach-imx/devices/devices.c.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>

ARM: SoC: convert imx6q to SMP operations

Convert the imx6q platform to use struct smp_operations to provide
its SMP and CPU hotplug operations.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

ARM: imx6: spin the cpu until hardware takes it down

Though commit 602bf40 (ARM: imx6: exit coherency when shutting down
a cpu) improves the stability of imx6q cpu hotplug a lot, there are
still hangs seen with a more stressful hotplug testing.

It's expected that once imx_enable_cpu(cpu, false) is called, the cpu
will be taken down by hardware immediately, and the code after that
will not get any chance to execute. However, this is not always the
case from the testing. The cpu could possibly be alive for a few
cycles before hardware actually takes it down. So rather than letting
cpu execute some code that could cause a hang in these cycles, let's
make the cpu spin there and wait for hardware to take it down.

Cc: <stable@vger.kernel.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

ARM: imx6: exit coherency when shutting down a cpu

There is a system hang issue on imx6q which can easily be seen with
running a cpu hotplug stress testing (hotplug secondary cores from
user space via sysfs interface for thousands iterations).

It turns out that the issue is caused by coherency of the cpu that
is being shut down. When shutting down a cpu, we need to have the
cpu exit coherency to prevent it from receiving cache, TLB, or BTB
maintenance operations broadcast by other CPUs in the cluster.

Copy cpu_enter_lowpower() and cpu_leave_lowpower() from mach-vexpress
to have coherency properly handled in platform_cpu_die(), thus fix
the issue.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: stable@kernel.org

arm/imx6q: add smp and cpu hotplug support

It adds smp and cpu hotplug support for imx6q.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>