bbc81fd432
platform_cpu_die() is entered from the CPU's own idle thread, which can not be migrated to other CPUs. Moreover, the 'cpu' argument comes from the thread info, which will always be the 'current' CPU. So remove this useless bug check. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
125 lines
2.5 KiB
C
125 lines
2.5 KiB
C
/*
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* linux/arch/arm/mach-realview/hotplug.c
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*
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* Copyright (C) 2002 ARM Ltd.
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/smp.h>
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#include <asm/cacheflush.h>
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static inline void cpu_enter_lowpower(void)
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{
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unsigned int v;
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flush_cache_all();
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asm volatile(
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" mcr p15, 0, %1, c7, c5, 0\n"
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" mcr p15, 0, %1, c7, c10, 4\n"
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/*
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* Turn off coherency
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*/
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" mrc p15, 0, %0, c1, c0, 1\n"
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" bic %0, %0, #0x20\n"
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" mcr p15, 0, %0, c1, c0, 1\n"
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" mrc p15, 0, %0, c1, c0, 0\n"
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" bic %0, %0, #0x04\n"
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" mcr p15, 0, %0, c1, c0, 0\n"
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: "=&r" (v)
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: "r" (0)
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: "cc");
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}
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static inline void cpu_leave_lowpower(void)
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{
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unsigned int v;
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asm volatile(
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"mrc p15, 0, %0, c1, c0, 0\n"
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" orr %0, %0, #0x04\n"
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" mcr p15, 0, %0, c1, c0, 0\n"
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" mrc p15, 0, %0, c1, c0, 1\n"
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" orr %0, %0, #0x20\n"
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" mcr p15, 0, %0, c1, c0, 1\n"
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: "=&r" (v)
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:
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: "cc");
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}
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static inline void platform_do_lowpower(unsigned int cpu)
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{
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/*
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* there is no power-control hardware on this platform, so all
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* we can do is put the core into WFI; this is safe as the calling
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* code will have already disabled interrupts
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*/
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for (;;) {
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/*
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* here's the WFI
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*/
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asm(".word 0xe320f003\n"
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:
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:
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: "memory", "cc");
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/*if (pen_release == cpu) {*/
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/*
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* OK, proper wakeup, we're done
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*/
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break;
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/*}*/
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/*
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* getting here, means that we have come out of WFI without
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* having been woken up - this shouldn't happen
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*
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* The trouble is, letting people know about this is not really
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* possible, since we are currently running incoherently, and
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* therefore cannot safely call printk() or anything else
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*/
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#ifdef DEBUG
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printk(KERN_WARN "CPU%u: spurious wakeup call\n", cpu);
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#endif
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}
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}
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int platform_cpu_kill(unsigned int cpu)
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{
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return 1;
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}
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/*
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* platform-specific code to shutdown a CPU
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*
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* Called with IRQs disabled
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*/
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void platform_cpu_die(unsigned int cpu)
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{
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/*
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* we're ready for shutdown now, so do it
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*/
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cpu_enter_lowpower();
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platform_do_lowpower(cpu);
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/*
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* bring this CPU back into the world of cache
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* coherency, and then restore interrupts
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*/
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cpu_leave_lowpower();
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}
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int platform_cpu_disable(unsigned int cpu)
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{
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/*
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* we don't allow CPU 0 to be shutdown (it is still too special
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* e.g. clock tick interrupts)
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*/
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return cpu == 0 ? -EPERM : 0;
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}
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