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 16 #include <asm/cacheflush.h> 17 18 static DECLARE_COMPLETION(cpu_killed); 19 20 static inline void cpu_enter_lowpower(void) 21 { 22 unsigned int v; 23 24 flush_cache_all(); 25 asm volatile( 26 " mcr p15, 0, %1, c7, c5, 0\n" 27 " mcr p15, 0, %1, c7, c10, 4\n" 28 /* 29 * Turn off coherency 30 */ 31 " mrc p15, 0, %0, c1, c0, 1\n" 32 " bic %0, %0, #0x20\n" 33 " mcr p15, 0, %0, c1, c0, 1\n" 34 " mrc p15, 0, %0, c1, c0, 0\n" 35 " bic %0, %0, #0x04\n" 36 " mcr p15, 0, %0, c1, c0, 0\n" 37 : "=&r" (v) 38 : "r" (0) 39 : "cc"); 40 } 41 42 static inline void cpu_leave_lowpower(void) 43 { 44 unsigned int v; 45 46 asm volatile( 47 "mrc p15, 0, %0, c1, c0, 0\n" 48 " orr %0, %0, #0x04\n" 49 " mcr p15, 0, %0, c1, c0, 0\n" 50 " mrc p15, 0, %0, c1, c0, 1\n" 51 " orr %0, %0, #0x20\n" 52 " mcr p15, 0, %0, c1, c0, 1\n" 53 : "=&r" (v) 54 : 55 : "cc"); 56 } 57 58 static inline void platform_do_lowpower(unsigned int cpu) 59 { 60 /* 61 * there is no power-control hardware on this platform, so all 62 * we can do is put the core into WFI; this is safe as the calling 63 * code will have already disabled interrupts 64 */ 65 for (;;) { 66 /* 67 * here's the WFI 68 */ 69 asm(".word 0xe320f003\n" 70 : 71 : 72 : "memory", "cc"); 73 74 /*if (pen_release == cpu) {*/ 75 /* 76 * OK, proper wakeup, we're done 77 */ 78 break; 79 /*}*/ 80 81 /* 82 * getting here, means that we have come out of WFI without 83 * having been woken up - this shouldn't happen 84 * 85 * The trouble is, letting people know about this is not really 86 * possible, since we are currently running incoherently, and 87 * therefore cannot safely call printk() or anything else 88 */ 89 #ifdef DEBUG 90 printk(KERN_WARN "CPU%u: spurious wakeup call\n", cpu); 91 #endif 92 } 93 } 94 95 int platform_cpu_kill(unsigned int cpu) 96 { 97 return wait_for_completion_timeout(&cpu_killed, 5000); 98 } 99 100 /* 101 * platform-specific code to shutdown a CPU 102 * 103 * Called with IRQs disabled 104 */ 105 void platform_cpu_die(unsigned int cpu) 106 { 107 #ifdef DEBUG 108 unsigned int this_cpu = hard_smp_processor_id(); 109 110 if (cpu != this_cpu) { 111 printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n", 112 this_cpu, cpu); 113 BUG(); 114 } 115 #endif 116 117 printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); 118 complete(&cpu_killed); 119 120 /* 121 * we're ready for shutdown now, so do it 122 */ 123 cpu_enter_lowpower(); 124 platform_do_lowpower(cpu); 125 126 /* 127 * bring this CPU back into the world of cache 128 * coherency, and then restore interrupts 129 */ 130 cpu_leave_lowpower(); 131 } 132 133 int platform_cpu_disable(unsigned int cpu) 134 { 135 /* 136 * we don't allow CPU 0 to be shutdown (it is still too special 137 * e.g. clock tick interrupts) 138 */ 139 return cpu == 0 ? -EPERM : 0; 140 } 141