142 lines
2.9 KiB
C
142 lines
2.9 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 <linux/completion.h>
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#include <asm/cacheflush.h>
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extern volatile int pen_release;
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static DECLARE_COMPLETION(cpu_killed);
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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( "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("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 wait_for_completion_timeout(&cpu_killed, 5000);
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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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#ifdef DEBUG
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unsigned int this_cpu = hard_smp_processor_id();
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if (cpu != this_cpu) {
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printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",
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this_cpu, cpu);
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BUG();
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}
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#endif
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printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
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complete(&cpu_killed);
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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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