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");
+
+}
+
+