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/cacheflush.h> 16 17 static inline void cpu_enter_lowpower(void) 18 { 19 unsigned int v; 20 21 flush_cache_all(); 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 39 static inline void cpu_leave_lowpower(void) 40 { 41 unsigned int v; 42 43 asm volatile( 44 "mrc p15, 0, %0, c1, c0, 0\n" 45 " orr %0, %0, %1\n" 46 " mcr p15, 0, %0, c1, c0, 0\n" 47 " mrc p15, 0, %0, c1, c0, 1\n" 48 " orr %0, %0, #0x20\n" 49 " mcr p15, 0, %0, c1, c0, 1\n" 50 : "=&r" (v) 51 : "Ir" (CR_C) 52 : "cc"); 53 } 54 55 static inline void platform_do_lowpower(unsigned int cpu, int *spurious) 56 { 57 /* 58 * there is no power-control hardware on this platform, so all 59 * we can do is put the core into WFI; this is safe as the calling 60 * code will have already disabled interrupts 61 */ 62 for (;;) { 63 /* 64 * here's the WFI 65 */ 66 asm(".word 0xe320f003\n" 67 : 68 : 69 : "memory", "cc"); 70 71 /*if (pen_release == cpu) {*/ 72 /* 73 * OK, proper wakeup, we're done 74 */ 75 break; 76 /*}*/ 77 78 /* 79 * Getting here, means that we have come out of WFI without 80 * having been woken up - this shouldn't happen 81 * 82 * Just note it happening - when we're woken, we can report 83 * its occurrence. 84 */ 85 (*spurious)++; 86 } 87 } 88 89 int platform_cpu_kill(unsigned int cpu) 90 { 91 return 1; 92 } 93 94 /* 95 * platform-specific code to shutdown a CPU 96 * 97 * Called with IRQs disabled 98 */ 99 void platform_cpu_die(unsigned int cpu) 100 { 101 int spurious = 0; 102 103 /* 104 * we're ready for shutdown now, so do it 105 */ 106 cpu_enter_lowpower(); 107 platform_do_lowpower(cpu, &spurious); 108 109 /* 110 * bring this CPU back into the world of cache 111 * coherency, and then restore interrupts 112 */ 113 cpu_leave_lowpower(); 114 115 if (spurious) 116 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); 117 } 118 119 int platform_cpu_disable(unsigned int cpu) 120 { 121 /* 122 * we don't allow CPU 0 to be shutdown (it is still too special 123 * e.g. clock tick interrupts) 124 */ 125 return cpu == 0 ? -EPERM : 0; 126 } 127