v4.19.13 snapshot.
diff --git a/kernel/power/poweroff.c b/kernel/power/poweroff.c
new file mode 100644
index 0000000..7ef6866
--- /dev/null
+++ b/kernel/power/poweroff.c
@@ -0,0 +1,46 @@
+/*
+ * poweroff.c - sysrq handler to gracefully power down machine.
+ *
+ * This file is released under the GPL v2
+ */
+
+#include <linux/kernel.h>
+#include <linux/sysrq.h>
+#include <linux/init.h>
+#include <linux/pm.h>
+#include <linux/workqueue.h>
+#include <linux/reboot.h>
+#include <linux/cpumask.h>
+
+/*
+ * When the user hits Sys-Rq o to power down the machine this is the
+ * callback we use.
+ */
+
+static void do_poweroff(struct work_struct *dummy)
+{
+ kernel_power_off();
+}
+
+static DECLARE_WORK(poweroff_work, do_poweroff);
+
+static void handle_poweroff(int key)
+{
+ /* run sysrq poweroff on boot cpu */
+ schedule_work_on(cpumask_first(cpu_online_mask), &poweroff_work);
+}
+
+static struct sysrq_key_op sysrq_poweroff_op = {
+ .handler = handle_poweroff,
+ .help_msg = "poweroff(o)",
+ .action_msg = "Power Off",
+ .enable_mask = SYSRQ_ENABLE_BOOT,
+};
+
+static int __init pm_sysrq_init(void)
+{
+ register_sysrq_key('o', &sysrq_poweroff_op);
+ return 0;
+}
+
+subsys_initcall(pm_sysrq_init);