| Jeff Ohlstein | 9f1890a | 2010-12-02 12:11:27 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2002 ARM Ltd. |
| 3 | * All Rights Reserved |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | */ |
| 9 | #include <linux/kernel.h> |
| 10 | #include <linux/errno.h> |
| 11 | #include <linux/smp.h> |
| 12 | |
| 13 | #include <asm/cacheflush.h> |
| 14 | |
| 15 | extern volatile int pen_release; |
| 16 | |
| 17 | static inline void cpu_enter_lowpower(void) |
| 18 | { |
| 19 | /* Just flush the cache. Changing the coherency is not yet |
| 20 | * available on msm. */ |
| 21 | flush_cache_all(); |
| 22 | } |
| 23 | |
| 24 | static inline void cpu_leave_lowpower(void) |
| 25 | { |
| 26 | } |
| 27 | |
| 28 | static inline void platform_do_lowpower(unsigned int cpu) |
| 29 | { |
| 30 | /* Just enter wfi for now. TODO: Properly shut off the cpu. */ |
| 31 | for (;;) { |
| 32 | /* |
| 33 | * here's the WFI |
| 34 | */ |
| 35 | asm("wfi" |
| 36 | : |
| 37 | : |
| 38 | : "memory", "cc"); |
| 39 | |
| 40 | if (pen_release == cpu) { |
| 41 | /* |
| 42 | * OK, proper wakeup, we're done |
| 43 | */ |
| 44 | break; |
| 45 | } |
| 46 | |
| 47 | /* |
| 48 | * getting here, means that we have come out of WFI without |
| 49 | * having been woken up - this shouldn't happen |
| 50 | * |
| 51 | * The trouble is, letting people know about this is not really |
| 52 | * possible, since we are currently running incoherently, and |
| 53 | * therefore cannot safely call printk() or anything else |
| 54 | */ |
| 55 | pr_debug("CPU%u: spurious wakeup call\n", cpu); |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | int platform_cpu_kill(unsigned int cpu) |
| 60 | { |
| 61 | return 1; |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * platform-specific code to shutdown a CPU |
| 66 | * |
| 67 | * Called with IRQs disabled |
| 68 | */ |
| 69 | void platform_cpu_die(unsigned int cpu) |
| 70 | { |
| 71 | /* |
| 72 | * we're ready for shutdown now, so do it |
| 73 | */ |
| 74 | cpu_enter_lowpower(); |
| 75 | platform_do_lowpower(cpu); |
| 76 | |
| 77 | /* |
| 78 | * bring this CPU back into the world of cache |
| 79 | * coherency, and then restore interrupts |
| 80 | */ |
| 81 | cpu_leave_lowpower(); |
| 82 | } |
| 83 | |
| 84 | int platform_cpu_disable(unsigned int cpu) |
| 85 | { |
| 86 | /* |
| 87 | * we don't allow CPU 0 to be shutdown (it is still too special |
| 88 | * e.g. clock tick interrupts) |
| 89 | */ |
| 90 | return cpu == 0 ? -EPERM : 0; |
| 91 | } |