linux/arch/arm/mach-shmobile/hotplug.c
Magnus Damm 1229835ccb ARM: mach-shmobile: Flush caches in platform_cpu_die()
Add cache flushing code to the SH-Mobile specific CPU hotplug
implementation. While at it, add a cpu mask to make sure the
cache flushing code is finished in platform_cpu_die() before
letting the SoC-specific code in shmobile_platform_cpu_kill()
proceed with turning off power.

Without this code CPU hotplug offline fails when cache is
enabled on Cortex-A9 based SoCs.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2012-01-09 10:37:29 +09:00

72 lines
1.6 KiB
C

/*
* SMP support for R-Mobile / SH-Mobile
*
* Copyright (C) 2010 Magnus Damm
*
* Based on realview, Copyright (C) 2002 ARM Ltd, All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <mach/common.h>
#include <asm/cacheflush.h>
static cpumask_t dead_cpus;
int platform_cpu_kill(unsigned int cpu)
{
int k;
/* this function is running on another CPU than the offline target,
* here we need wait for shutdown code in platform_cpu_die() to
* finish before asking SoC-specific code to power off the CPU core.
*/
for (k = 0; k < 1000; k++) {
if (cpumask_test_cpu(cpu, &dead_cpus))
return shmobile_platform_cpu_kill(cpu);
mdelay(1);
}
return 0;
}
void platform_cpu_die(unsigned int cpu)
{
/* hardware shutdown code running on the CPU that is being offlined */
flush_cache_all();
dsb();
/* notify platform_cpu_kill() that hardware shutdown is finished */
cpumask_set_cpu(cpu, &dead_cpus);
/* wait for SoC code in platform_cpu_kill() to shut off CPU core
* power. CPU bring up starts from the reset vector.
*/
while (1) {
/*
* here's the WFI
*/
asm(".word 0xe320f003\n"
:
:
: "memory", "cc");
}
}
int platform_cpu_disable(unsigned int cpu)
{
cpumask_clear_cpu(cpu, &dead_cpus);
/*
* we don't allow CPU 0 to be shutdown (it is still too special
* e.g. clock tick interrupts)
*/
return cpu == 0 ? -EPERM : 0;
}