v4.19.13 snapshot.
diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/ledtrig-cpu.c
new file mode 100644
index 0000000..66a6260
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-cpu.c
@@ -0,0 +1,169 @@
+/*
+ * ledtrig-cpu.c - LED trigger based on CPU activity
+ *
+ * This LED trigger will be registered for each possible CPU and named as
+ * cpu0, cpu1, cpu2, cpu3, etc.
+ *
+ * It can be bound to any LED just like other triggers using either a
+ * board file or via sysfs interface.
+ *
+ * An API named ledtrig_cpu is exported for any user, who want to add CPU
+ * activity indication in their code
+ *
+ * Copyright 2011 Linus Walleij <linus.walleij@linaro.org>
+ * Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/percpu.h>
+#include <linux/syscore_ops.h>
+#include <linux/rwsem.h>
+#include <linux/cpu.h>
+#include "../leds.h"
+
+#define MAX_NAME_LEN 8
+
+struct led_trigger_cpu {
+ bool is_active;
+ char name[MAX_NAME_LEN];
+ struct led_trigger *_trig;
+};
+
+static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
+
+static struct led_trigger *trig_cpu_all;
+static atomic_t num_active_cpus = ATOMIC_INIT(0);
+
+/**
+ * ledtrig_cpu - emit a CPU event as a trigger
+ * @evt: CPU event to be emitted
+ *
+ * Emit a CPU event on a CPU core, which will trigger a
+ * bound LED to turn on or turn off.
+ */
+void ledtrig_cpu(enum cpu_led_event ledevt)
+{
+ struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig);
+ bool is_active = trig->is_active;
+
+ /* Locate the correct CPU LED */
+ switch (ledevt) {
+ case CPU_LED_IDLE_END:
+ case CPU_LED_START:
+ /* Will turn the LED on, max brightness */
+ is_active = true;
+ break;
+
+ case CPU_LED_IDLE_START:
+ case CPU_LED_STOP:
+ case CPU_LED_HALTED:
+ /* Will turn the LED off */
+ is_active = false;
+ break;
+
+ default:
+ /* Will leave the LED as it is */
+ break;
+ }
+
+ if (is_active != trig->is_active) {
+ unsigned int active_cpus;
+ unsigned int total_cpus;
+
+ /* Update trigger state */
+ trig->is_active = is_active;
+ atomic_add(is_active ? 1 : -1, &num_active_cpus);
+ active_cpus = atomic_read(&num_active_cpus);
+ total_cpus = num_present_cpus();
+
+ led_trigger_event(trig->_trig,
+ is_active ? LED_FULL : LED_OFF);
+
+
+ led_trigger_event(trig_cpu_all,
+ DIV_ROUND_UP(LED_FULL * active_cpus, total_cpus));
+
+ }
+}
+EXPORT_SYMBOL(ledtrig_cpu);
+
+static int ledtrig_cpu_syscore_suspend(void)
+{
+ ledtrig_cpu(CPU_LED_STOP);
+ return 0;
+}
+
+static void ledtrig_cpu_syscore_resume(void)
+{
+ ledtrig_cpu(CPU_LED_START);
+}
+
+static void ledtrig_cpu_syscore_shutdown(void)
+{
+ ledtrig_cpu(CPU_LED_HALTED);
+}
+
+static struct syscore_ops ledtrig_cpu_syscore_ops = {
+ .shutdown = ledtrig_cpu_syscore_shutdown,
+ .suspend = ledtrig_cpu_syscore_suspend,
+ .resume = ledtrig_cpu_syscore_resume,
+};
+
+static int ledtrig_online_cpu(unsigned int cpu)
+{
+ ledtrig_cpu(CPU_LED_START);
+ return 0;
+}
+
+static int ledtrig_prepare_down_cpu(unsigned int cpu)
+{
+ ledtrig_cpu(CPU_LED_STOP);
+ return 0;
+}
+
+static int __init ledtrig_cpu_init(void)
+{
+ int cpu;
+ int ret;
+
+ /* Supports up to 9999 cpu cores */
+ BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
+
+ /*
+ * Registering a trigger for all CPUs.
+ */
+ led_trigger_register_simple("cpu", &trig_cpu_all);
+
+ /*
+ * Registering CPU led trigger for each CPU core here
+ * ignores CPU hotplug, but after this CPU hotplug works
+ * fine with this trigger.
+ */
+ for_each_possible_cpu(cpu) {
+ struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
+
+ snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
+
+ led_trigger_register_simple(trig->name, &trig->_trig);
+ }
+
+ register_syscore_ops(&ledtrig_cpu_syscore_ops);
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting",
+ ledtrig_online_cpu, ledtrig_prepare_down_cpu);
+ if (ret < 0)
+ pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n",
+ ret);
+
+ pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
+
+ return 0;
+}
+device_initcall(ledtrig_cpu_init);