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ARM: pm: add function to set WFI low-power mode for SMP CPUs

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Add a function to set the SCU low-power mode for SMP CPUs.  This
centralizes this functionality rather than having to expose the
SCU register definitions to each platform.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2011-02-04 10:36:39 +00:00
parent afe8a88755
commit 292ec42af7
2 changed files with 30 additions and 0 deletions
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7
arch/arm/include/asm/smp_scu.h
View File

@ -1,7 +1,14 @@
#ifndef __ASMARM_ARCH_SCU_H
#define __ASMARM_ARCH_SCU_H
#define SCU_PM_NORMAL 0
#define SCU_PM_DORMANT 2
#define SCU_PM_POWEROFF 3
#ifndef __ASSEMBLER__
unsigned int scu_get_core_count(void __iomem *);
void scu_enable(void __iomem *);
int scu_power_mode(void __iomem *, unsigned int);
#endif
#endif

23
arch/arm/kernel/smp_scu.c
View File

@ -50,3 +50,26 @@ void __init scu_enable(void __iomem *scu_base)
*/
flush_cache_all();
}
/*
* Set the executing CPUs power mode as defined. This will be in
* preparation for it executing a WFI instruction.
*
* This function must be called with preemption disabled, and as it
* has the side effect of disabling coherency, caches must have been
* flushed. Interrupts must also have been disabled.
*/
int scu_power_mode(void __iomem *scu_base, unsigned int mode)
{
unsigned int val;
int cpu = smp_processor_id();
if (mode > 3 || mode == 1 || cpu > 3)
return -EINVAL;
val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
val |= mode;
__raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
return 0;
}