diff options
Diffstat (limited to 'kernel/power/smp.c')
| -rw-r--r-- | kernel/power/smp.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/kernel/power/smp.c b/kernel/power/smp.c new file mode 100644 index 000000000000..7fa7f6e2b7fb --- /dev/null +++ b/kernel/power/smp.c @@ -0,0 +1,85 @@ +/* + * drivers/power/smp.c - Functions for stopping other CPUs. + * + * Copyright 2004 Pavel Machek <pavel@suse.cz> + * Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz> + * + * This file is released under the GPLv2. + */ + +#undef DEBUG + +#include <linux/smp_lock.h> +#include <linux/interrupt.h> +#include <linux/suspend.h> +#include <linux/module.h> +#include <asm/atomic.h> +#include <asm/tlbflush.h> + +static atomic_t cpu_counter, freeze; + + +static void smp_pause(void * data) +{ + struct saved_context ctxt; + __save_processor_state(&ctxt); + printk("Sleeping in:\n"); + dump_stack(); + atomic_inc(&cpu_counter); + while (atomic_read(&freeze)) { + /* FIXME: restore takes place at random piece inside this. + This should probably be written in assembly, and + preserve general-purpose registers, too + + What about stack? We may need to move to new stack here. + + This should better be ran with interrupts disabled. + */ + cpu_relax(); + barrier(); + } + atomic_dec(&cpu_counter); + __restore_processor_state(&ctxt); +} + +static cpumask_t oldmask; + +void disable_nonboot_cpus(void) +{ + printk("Freezing CPUs (at %d)", smp_processor_id()); + oldmask = current->cpus_allowed; + set_cpus_allowed(current, cpumask_of_cpu(0)); + current->state = TASK_INTERRUPTIBLE; + schedule_timeout(HZ); + printk("..."); + BUG_ON(smp_processor_id() != 0); + + /* FIXME: for this to work, all the CPUs must be running + * "idle" thread (or we deadlock). Is that guaranteed? */ + + atomic_set(&cpu_counter, 0); + atomic_set(&freeze, 1); + smp_call_function(smp_pause, NULL, 0, 0); + while (atomic_read(&cpu_counter) < (num_online_cpus() - 1)) { + cpu_relax(); + barrier(); + } + printk("ok\n"); +} + +void enable_nonboot_cpus(void) +{ + printk("Restarting CPUs"); + atomic_set(&freeze, 0); + while (atomic_read(&cpu_counter)) { + cpu_relax(); + barrier(); + } + printk("..."); + set_cpus_allowed(current, oldmask); + schedule(); + printk("ok\n"); + +} + + |