/* * linux/arch/arm/mach-realview/hotplug.c * * 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/completion.h> #include <asm/cacheflush.h> static DECLARE_COMPLETION(cpu_killed); static inline void cpu_enter_lowpower(void) { unsigned int v; flush_cache_all(); asm volatile( " mcr p15, 0, %1, c7, c5, 0\n" " mcr p15, 0, %1, c7, c10, 4\n" /* * Turn off coherency */ " mrc p15, 0, %0, c1, c0, 1\n" " bic %0, %0, #0x20\n" " mcr p15, 0, %0, c1, c0, 1\n" " mrc p15, 0, %0, c1, c0, 0\n" " bic %0, %0, #0x04\n" " mcr p15, 0, %0, c1, c0, 0\n" : "=&r" (v) : "r" (0) : "cc"); } static inline void cpu_leave_lowpower(void) { unsigned int v; asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" " orr %0, %0, #0x04\n" " mcr p15, 0, %0, c1, c0, 0\n" " mrc p15, 0, %0, c1, c0, 1\n" " orr %0, %0, #0x20\n" " mcr p15, 0, %0, c1, c0, 1\n" : "=&r" (v) : : "cc"); } static inline void platform_do_lowpower(unsigned int cpu) { /* * there is no power-control hardware on this platform, so all * we can do is put the core into WFI; this is safe as the calling * code will have already disabled interrupts */ for (;;) { /* * here's the WFI */ asm(".word 0xe320f003\n" : : : "memory", "cc"); /*if (pen_release == cpu) {*/ /* * OK, proper wakeup, we're done */ break; /*}*/ /* * getting here, means that we have come out of WFI without * having been woken up - this shouldn't happen * * The trouble is, letting people know about this is not really * possible, since we are currently running incoherently, and * therefore cannot safely call printk() or anything else */ #ifdef DEBUG printk(KERN_WARN "CPU%u: spurious wakeup call\n", cpu); #endif } } int platform_cpu_kill(unsigned int cpu) { return wait_for_completion_timeout(&cpu_killed, 5000); } /* * platform-specific code to shutdown a CPU * * Called with IRQs disabled */ void platform_cpu_die(unsigned int cpu) { #ifdef DEBUG unsigned int this_cpu = hard_smp_processor_id(); if (cpu != this_cpu) { printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n", this_cpu, cpu); BUG(); } #endif printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); complete(&cpu_killed); /* * we're ready for shutdown now, so do it */ cpu_enter_lowpower(); platform_do_lowpower(cpu); /* * bring this CPU back into the world of cache * coherency, and then restore interrupts */ cpu_leave_lowpower(); } int platform_cpu_disable(unsigned int cpu) { /* * we don't allow CPU 0 to be shutdown (it is still too special * e.g. clock tick interrupts) */ return cpu == 0 ? -EPERM : 0; }