Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * drivers/power/smp.c - Functions for stopping other CPUs. |
| 3 | * |
| 4 | * Copyright 2004 Pavel Machek <pavel@suse.cz> |
| 5 | * Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz> |
| 6 | * |
| 7 | * This file is released under the GPLv2. |
| 8 | */ |
| 9 | |
| 10 | #undef DEBUG |
| 11 | |
| 12 | #include <linux/smp_lock.h> |
| 13 | #include <linux/interrupt.h> |
| 14 | #include <linux/suspend.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <asm/atomic.h> |
| 17 | #include <asm/tlbflush.h> |
| 18 | |
| 19 | static atomic_t cpu_counter, freeze; |
| 20 | |
| 21 | |
| 22 | static void smp_pause(void * data) |
| 23 | { |
| 24 | struct saved_context ctxt; |
| 25 | __save_processor_state(&ctxt); |
| 26 | printk("Sleeping in:\n"); |
| 27 | dump_stack(); |
| 28 | atomic_inc(&cpu_counter); |
| 29 | while (atomic_read(&freeze)) { |
| 30 | /* FIXME: restore takes place at random piece inside this. |
| 31 | This should probably be written in assembly, and |
| 32 | preserve general-purpose registers, too |
| 33 | |
| 34 | What about stack? We may need to move to new stack here. |
| 35 | |
| 36 | This should better be ran with interrupts disabled. |
| 37 | */ |
| 38 | cpu_relax(); |
| 39 | barrier(); |
| 40 | } |
| 41 | atomic_dec(&cpu_counter); |
| 42 | __restore_processor_state(&ctxt); |
| 43 | } |
| 44 | |
| 45 | static cpumask_t oldmask; |
| 46 | |
| 47 | void disable_nonboot_cpus(void) |
| 48 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | oldmask = current->cpus_allowed; |
| 50 | set_cpus_allowed(current, cpumask_of_cpu(0)); |
Alexander Nyberg | 43117a0 | 2005-04-16 15:25:39 -0700 | [diff] [blame] | 51 | printk("Freezing CPUs (at %d)", _smp_processor_id()); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | current->state = TASK_INTERRUPTIBLE; |
| 53 | schedule_timeout(HZ); |
| 54 | printk("..."); |
Alexander Nyberg | 43117a0 | 2005-04-16 15:25:39 -0700 | [diff] [blame] | 55 | BUG_ON(_smp_processor_id() != 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | |
| 57 | /* FIXME: for this to work, all the CPUs must be running |
| 58 | * "idle" thread (or we deadlock). Is that guaranteed? */ |
| 59 | |
| 60 | atomic_set(&cpu_counter, 0); |
| 61 | atomic_set(&freeze, 1); |
| 62 | smp_call_function(smp_pause, NULL, 0, 0); |
| 63 | while (atomic_read(&cpu_counter) < (num_online_cpus() - 1)) { |
| 64 | cpu_relax(); |
| 65 | barrier(); |
| 66 | } |
| 67 | printk("ok\n"); |
| 68 | } |
| 69 | |
| 70 | void enable_nonboot_cpus(void) |
| 71 | { |
| 72 | printk("Restarting CPUs"); |
| 73 | atomic_set(&freeze, 0); |
| 74 | while (atomic_read(&cpu_counter)) { |
| 75 | cpu_relax(); |
| 76 | barrier(); |
| 77 | } |
| 78 | printk("..."); |
| 79 | set_cpus_allowed(current, oldmask); |
| 80 | schedule(); |
| 81 | printk("ok\n"); |
| 82 | |
| 83 | } |
| 84 | |
| 85 | |