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#include <linux/completion.h> 15 16extern volatile int pen_release; 17 18static DECLARE_COMPLETION(cpu_killed); 19 20static inline void cpu_enter_lowpower(void) 21{ 22 unsigned int v; 23 24 asm volatile( "mcr p15, 0, %1, c7, c14, 0\n" 25 " mcr p15, 0, %1, c7, c5, 0\n" 26 " mcr p15, 0, %1, c7, c10, 4\n" 27 /* 28 * Turn off coherency 29 */ 30 " mrc p15, 0, %0, c1, c0, 1\n" 31 " bic %0, %0, #0x20\n" 32 " mcr p15, 0, %0, c1, c0, 1\n" 33 " mrc p15, 0, %0, c1, c0, 0\n" 34 " bic %0, %0, #0x04\n" 35 " mcr p15, 0, %0, c1, c0, 0\n" 36 : "=&r" (v) 37 : "r" (0) 38 : "cc"); 39} 40 41static inline void cpu_leave_lowpower(void) 42{ 43 unsigned int v; 44 45 asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" 46 " orr %0, %0, #0x04\n" 47 " mcr p15, 0, %0, c1, c0, 0\n" 48 " mrc p15, 0, %0, c1, c0, 1\n" 49 " orr %0, %0, #0x20\n" 50 " mcr p15, 0, %0, c1, c0, 1\n" 51 : "=&r" (v) 52 : 53 : "cc"); 54} 55 56static inline void platform_do_lowpower(unsigned int cpu) 57{ 58 /* 59 * there is no power-control hardware on this platform, so all 60 * we can do is put the core into WFI; this is safe as the calling 61 * code will have already disabled interrupts 62 */ 63 for (;;) { 64 /* 65 * here's the WFI 66 */ 67 asm(".word 0xe320f003\n" 68 : 69 : 70 : "memory", "cc"); 71 72 if (pen_release == cpu) { 73 /* 74 * OK, proper wakeup, we're done 75 */ 76 break; 77 } 78 79 /* 80 * getting here, means that we have come out of WFI without 81 * having been woken up - this shouldn't happen 82 * 83 * The trouble is, letting people know about this is not really 84 * possible, since we are currently running incoherently, and 85 * therefore cannot safely call printk() or anything else 86 */ 87#ifdef DEBUG 88 printk("CPU%u: spurious wakeup call\n", cpu); 89#endif 90 } 91} 92 93int platform_cpu_kill(unsigned int cpu) 94{ 95 return wait_for_completion_timeout(&cpu_killed, 5000); 96} 97 98/* 99 * platform-specific code to shutdown a CPU 100 * 101 * Called with IRQs disabled 102 */ 103void platform_cpu_die(unsigned int cpu) 104{ 105#ifdef DEBUG 106 unsigned int this_cpu = hard_smp_processor_id(); 107 108 if (cpu != this_cpu) { 109 printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n", 110 this_cpu, cpu); 111 BUG(); 112 } 113#endif 114 115 printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); 116 complete(&cpu_killed); 117 118 /* 119 * we're ready for shutdown now, so do it 120 */ 121 cpu_enter_lowpower(); 122 platform_do_lowpower(cpu); 123 124 /* 125 * bring this CPU back into the world of cache 126 * coherency, and then restore interrupts 127 */ 128 cpu_leave_lowpower(); 129} 130 131int mach_cpu_disable(unsigned int cpu) 132{ 133 /* 134 * we don't allow CPU 0 to be shutdown (it is still too special 135 * e.g. clock tick interrupts) 136 */ 137 return cpu == 0 ? -EPERM : 0; 138} 139