/* * 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 <asm/cacheflush.h> #include <asm/cp15.h> 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, %2\n" " mcr p15, 0, %0, c1, c0, 0\n" : "=&r" (v) : "r" (0), "Ir" (CR_C) : "cc"); } static inline void cpu_leave_lowpower(void) { unsigned int v; asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" " orr %0, %0, %1\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) : "Ir" (CR_C) : "cc"); } static inline void platform_do_lowpower(unsigned int cpu, int *spurious) { /* * 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 * * Just note it happening - when we're woken, we can report * its occurrence. */ (*spurious)++; } } int platform_cpu_kill(unsigned int cpu) { return 1; } /* * platform-specific code to shutdown a CPU * * Called with IRQs disabled */ void platform_cpu_die(unsigned int cpu) { int spurious = 0; /* * we're ready for shutdown now, so do it */ cpu_enter_lowpower(); platform_do_lowpower(cpu, &spurious); /* * bring this CPU back into the world of cache * coherency, and then restore interrupts */ cpu_leave_lowpower(); if (spurious) pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); } 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; }