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 #include <asm/cp15.h> 17 18 static inline void cpu_enter_lowpower(void) 19 { 20 unsigned int v; 21 22 flush_cache_all(); 23 asm volatile( 24 " mcr p15, 0, %1, c7, c5, 0\n" 25 " mcr p15, 0, %1, c7, c10, 4\n" 26 /* 27 * Turn off coherency 28 */ 29 " mrc p15, 0, %0, c1, c0, 1\n" 30 " bic %0, %0, #0x20\n" 31 " mcr p15, 0, %0, c1, c0, 1\n" 32 " mrc p15, 0, %0, c1, c0, 0\n" 33 " bic %0, %0, %2\n" 34 " mcr p15, 0, %0, c1, c0, 0\n" 35 : "=&r" (v) 36 : "r" (0), "Ir" (CR_C) 37 : "cc"); 38 } 39 40 static inline void cpu_leave_lowpower(void) 41 { 42 unsigned int v; 43 44 asm volatile( 45 "mrc p15, 0, %0, c1, c0, 0\n" 46 " orr %0, %0, %1\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 : "Ir" (CR_C) 53 : "cc"); 54 } 55 56 static inline void platform_do_lowpower(unsigned int cpu, int *spurious) 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 * Just note it happening - when we're woken, we can report 84 * its occurrence. 85 */ 86 (*spurious)++; 87 } 88 } 89 90 int platform_cpu_kill(unsigned int cpu) 91 { 92 return 1; 93 } 94 95 /* 96 * platform-specific code to shutdown a CPU 97 * 98 * Called with IRQs disabled 99 */ 100 void platform_cpu_die(unsigned int cpu) 101 { 102 int spurious = 0; 103 104 /* 105 * we're ready for shutdown now, so do it 106 */ 107 cpu_enter_lowpower(); 108 platform_do_lowpower(cpu, &spurious); 109 110 /* 111 * bring this CPU back into the world of cache 112 * coherency, and then restore interrupts 113 */ 114 cpu_leave_lowpower(); 115 116 if (spurious) 117 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); 118 } 119 120 int platform_cpu_disable(unsigned int cpu) 121 { 122 /* 123 * we don't allow CPU 0 to be shutdown (it is still too special 124 * e.g. clock tick interrupts) 125 */ 126 return cpu == 0 ? -EPERM : 0; 127 } 128