1/* 2 * linux/arch/arm/mach-realview/hotplug.c 3 * 4 * Copyright (C) 2002 ARM Ltd. 5 * All Rights Reserved 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11#include <linux/kernel.h> 12#include <linux/errno.h> 13#include <linux/smp.h> 14 15#include <asm/cp15.h> 16#include <asm/smp_plat.h> 17 18static inline void cpu_enter_lowpower(void) 19{ 20 unsigned int v; 21 22 asm volatile( 23 " mcr p15, 0, %1, c7, c5, 0\n" 24 " mcr p15, 0, %1, c7, c10, 4\n" 25 /* 26 * Turn off coherency 27 */ 28 " mrc p15, 0, %0, c1, c0, 1\n" 29 " bic %0, %0, #0x20\n" 30 " mcr p15, 0, %0, c1, c0, 1\n" 31 " mrc p15, 0, %0, c1, c0, 0\n" 32 " bic %0, %0, %2\n" 33 " mcr p15, 0, %0, c1, c0, 0\n" 34 : "=&r" (v) 35 : "r" (0), "Ir" (CR_C) 36 : "cc"); 37} 38 39static inline void cpu_leave_lowpower(void) 40{ 41 unsigned int v; 42 43 asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" 44 " orr %0, %0, %1\n" 45 " mcr p15, 0, %0, c1, c0, 0\n" 46 " mrc p15, 0, %0, c1, c0, 1\n" 47 " orr %0, %0, #0x20\n" 48 " mcr p15, 0, %0, c1, c0, 1\n" 49 : "=&r" (v) 50 : "Ir" (CR_C) 51 : "cc"); 52} 53 54static inline void platform_do_lowpower(unsigned int cpu, int *spurious) 55{ 56 /* 57 * there is no power-control hardware on this platform, so all 58 * we can do is put the core into WFI; this is safe as the calling 59 * code will have already disabled interrupts 60 */ 61 for (;;) { 62 /* 63 * here's the WFI 64 */ 65 asm(".word 0xe320f003\n" 66 : 67 : 68 : "memory", "cc"); 69 70 if (pen_release == cpu_logical_map(cpu)) { 71 /* 72 * OK, proper wakeup, we're done 73 */ 74 break; 75 } 76 77 /* 78 * Getting here, means that we have come out of WFI without 79 * having been woken up - this shouldn't happen 80 * 81 * Just note it happening - when we're woken, we can report 82 * its occurrence. 83 */ 84 (*spurious)++; 85 } 86} 87 88/* 89 * platform-specific code to shutdown a CPU 90 * 91 * Called with IRQs disabled 92 */ 93void realview_cpu_die(unsigned int cpu) 94{ 95 int spurious = 0; 96 97 /* 98 * we're ready for shutdown now, so do it 99 */ 100 cpu_enter_lowpower(); 101 platform_do_lowpower(cpu, &spurious); 102 103 /* 104 * bring this CPU back into the world of cache 105 * coherency, and then restore interrupts 106 */ 107 cpu_leave_lowpower(); 108 109 if (spurious) 110 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); 111} 112