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linux
ARM: pm: add function to set WFI low-power mode for SMP CPUs
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>
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arch/arm/include/asm/smp_scu.h
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arch/arm/include/asm/smp_scu.h
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#ifndef __ASMARM_ARCH_SCU_H
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#define __ASMARM_ARCH_SCU_H
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#define SCU_PM_NORMAL 0
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#define SCU_PM_DORMANT 2
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#define SCU_PM_POWEROFF 3
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#ifndef __ASSEMBLER__
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unsigned int scu_get_core_count(void __iomem *);
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void scu_enable(void __iomem *);
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int scu_power_mode(void __iomem *, unsigned int);
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#endif
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#endif
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arch/arm/kernel/smp_scu.c
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arch/arm/kernel/smp_scu.c
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*/
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flush_cache_all();
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}
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/*
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* Set the executing CPUs power mode as defined. This will be in
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* preparation for it executing a WFI instruction.
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*
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* This function must be called with preemption disabled, and as it
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* has the side effect of disabling coherency, caches must have been
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* flushed. Interrupts must also have been disabled.
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*/
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int scu_power_mode(void __iomem *scu_base, unsigned int mode)
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{
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unsigned int val;
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int cpu = smp_processor_id();
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if (mode > 3 || mode == 1 || cpu > 3)
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return -EINVAL;
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val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
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val |= mode;
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__raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
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return 0;
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}