| Viresh Kumar | e3978dc | 2012-04-19 22:23:13 +0530 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/arm/mach-spear13xx/hotplug.c |
| 3 | * |
| 4 | * Copyright (C) 2012 ST Microelectronics Ltd. |
| 5 | * Deepak Sikri <deepak.sikri@st.com> |
| 6 | * |
| 7 | * based upon linux/arch/arm/mach-realview/hotplug.c |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License version 2 as |
| 11 | * published by the Free Software Foundation. |
| 12 | */ |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/errno.h> |
| 15 | #include <linux/smp.h> |
| 16 | #include <asm/cacheflush.h> |
| 17 | #include <asm/cp15.h> |
| 18 | #include <asm/smp_plat.h> |
| 19 | |
| 20 | extern volatile int pen_release; |
| 21 | |
| 22 | static inline void cpu_enter_lowpower(void) |
| 23 | { |
| 24 | unsigned int v; |
| 25 | |
| 26 | flush_cache_all(); |
| 27 | asm volatile( |
| 28 | " mcr p15, 0, %1, c7, c5, 0\n" |
| 29 | " dsb\n" |
| 30 | /* |
| 31 | * Turn off coherency |
| 32 | */ |
| 33 | " mrc p15, 0, %0, c1, c0, 1\n" |
| 34 | " bic %0, %0, #0x20\n" |
| 35 | " mcr p15, 0, %0, c1, c0, 1\n" |
| 36 | " mrc p15, 0, %0, c1, c0, 0\n" |
| 37 | " bic %0, %0, %2\n" |
| 38 | " mcr p15, 0, %0, c1, c0, 0\n" |
| 39 | : "=&r" (v) |
| 40 | : "r" (0), "Ir" (CR_C) |
| 41 | : "cc", "memory"); |
| 42 | } |
| 43 | |
| 44 | static inline void cpu_leave_lowpower(void) |
| 45 | { |
| 46 | unsigned int v; |
| 47 | |
| 48 | asm volatile("mrc p15, 0, %0, c1, c0, 0\n" |
| 49 | " orr %0, %0, %1\n" |
| 50 | " mcr p15, 0, %0, c1, c0, 0\n" |
| 51 | " mrc p15, 0, %0, c1, c0, 1\n" |
| 52 | " orr %0, %0, #0x20\n" |
| 53 | " mcr p15, 0, %0, c1, c0, 1\n" |
| 54 | : "=&r" (v) |
| 55 | : "Ir" (CR_C) |
| 56 | : "cc"); |
| 57 | } |
| 58 | |
| 59 | static inline void platform_do_lowpower(unsigned int cpu, int *spurious) |
| 60 | { |
| 61 | for (;;) { |
| 62 | wfi(); |
| 63 | |
| 64 | if (pen_release == cpu) { |
| 65 | /* |
| 66 | * OK, proper wakeup, we're done |
| 67 | */ |
| 68 | break; |
| 69 | } |
| 70 | |
| 71 | /* |
| 72 | * Getting here, means that we have come out of WFI without |
| 73 | * having been woken up - this shouldn't happen |
| 74 | * |
| 75 | * Just note it happening - when we're woken, we can report |
| 76 | * its occurrence. |
| 77 | */ |
| 78 | (*spurious)++; |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | int platform_cpu_kill(unsigned int cpu) |
| 83 | { |
| 84 | return 1; |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * platform-specific code to shutdown a CPU |
| 89 | * |
| 90 | * Called with IRQs disabled |
| 91 | */ |
| 92 | void __cpuinit platform_cpu_die(unsigned int cpu) |
| 93 | { |
| 94 | int spurious = 0; |
| 95 | |
| 96 | /* |
| 97 | * we're ready for shutdown now, so do it |
| 98 | */ |
| 99 | cpu_enter_lowpower(); |
| 100 | platform_do_lowpower(cpu, &spurious); |
| 101 | |
| 102 | /* |
| 103 | * bring this CPU back into the world of cache |
| 104 | * coherency, and then restore interrupts |
| 105 | */ |
| 106 | cpu_leave_lowpower(); |
| 107 | |
| 108 | if (spurious) |
| 109 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); |
| 110 | } |
| 111 | |
| 112 | int platform_cpu_disable(unsigned int cpu) |
| 113 | { |
| 114 | /* |
| 115 | * we don't allow CPU 0 to be shutdown (it is still too special |
| 116 | * e.g. clock tick interrupts) |
| 117 | */ |
| 118 | return cpu == 0 ? -EPERM : 0; |
| 119 | } |