summaryrefslogtreecommitdiffstats
path: root/kernel/power/smp.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/power/smp.c')
-rw-r--r--kernel/power/smp.c85
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");
+
+}
+
+