diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 12b2b55c519e..c96fd29199da 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -469,6 +469,16 @@ config LEDS_TRIGGER_BACKLIGHT
If unsure, say N.
+config LEDS_TRIGGER_CPU
+ bool "LED CPU Trigger"
+ depends on LEDS_TRIGGERS
+ help
+ This allows LEDs to be controlled by active CPUs. This shows
+ the active CPUs across an array of LEDs so you can see which
+ CPUs are active on the system at any given moment.
+
+ If unsure, say N.
+
config LEDS_TRIGGER_GPIO
tristate "LED GPIO Trigger"
depends on LEDS_TRIGGERS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index f8958cd6cf6e..fa0f53626618 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -57,5 +57,6 @@ obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK) += ledtrig-ide-disk.o
obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT) += ledtrig-heartbeat.o
obj-$(CONFIG_LEDS_TRIGGER_BACKLIGHT) += ledtrig-backlight.o
obj-$(CONFIG_LEDS_TRIGGER_GPIO) += ledtrig-gpio.o
+obj-$(CONFIG_LEDS_TRIGGER_CPU) += ledtrig-cpu.o
obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT) += ledtrig-transient.o
diff --git a/drivers/leds/ledtrig-cpu.c b/drivers/leds/ledtrig-cpu.c
new file mode 100644
index 000000000000..b312056da14d
--- /dev/null
+++ b/drivers/leds/ledtrig-cpu.c
@@ -0,0 +1,163 @@
+/*
+ * 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/module.h>
+#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 "leds.h"
+
+#define MAX_NAME_LEN 8
+
+struct led_trigger_cpu {
+ char name[MAX_NAME_LEN];
+ struct led_trigger *_trig;
+ struct mutex lock;
+ int lock_is_inited;
+};
+
+static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
+
+/**
+ * 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
+ * binded LED to turn on or turn off.
+ */
+void ledtrig_cpu(enum cpu_led_event ledevt)
+{
+ struct led_trigger_cpu *trig = &__get_cpu_var(cpu_trig);
+
+ /* mutex lock should be initialized before calling mutex_call() */
+ if (!trig->lock_is_inited)
+ return;
+
+ mutex_lock(&trig->lock);
+
+ /* Locate the correct CPU LED */
+ switch (ledevt) {
+ case CPU_LED_IDLE_END:
+ case CPU_LED_START:
+ /* Will turn the LED on, max brightness */
+ led_trigger_event(trig->_trig, LED_FULL);
+ break;
+
+ case CPU_LED_IDLE_START:
+ case CPU_LED_STOP:
+ case CPU_LED_HALTED:
+ /* Will turn the LED off */
+ led_trigger_event(trig->_trig, LED_OFF);
+ break;
+
+ default:
+ /* Will leave the LED as it is */
+ break;
+ }
+
+ mutex_unlock(&trig->lock);
+}
+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 __init ledtrig_cpu_init(void)
+{
+ int cpu;
+
+ /* Supports up to 9999 cpu cores */
+ BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
+
+ /*
+ * 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);
+
+ mutex_init(&trig->lock);
+
+ snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
+
+ mutex_lock(&trig->lock);
+ led_trigger_register_simple(trig->name, &trig->_trig);
+ trig->lock_is_inited = 1;
+ mutex_unlock(&trig->lock);
+ }
+
+ register_syscore_ops(&ledtrig_cpu_syscore_ops);
+
+ pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
+
+ return 0;
+}
+module_init(ledtrig_cpu_init);
+
+static void __exit ledtrig_cpu_exit(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
+
+ mutex_lock(&trig->lock);
+
+ led_trigger_unregister_simple(trig->_trig);
+ trig->_trig = NULL;
+ memset(trig->name, 0, MAX_NAME_LEN);
+ trig->lock_is_inited = 0;
+
+ mutex_unlock(&trig->lock);
+ mutex_destroy(&trig->lock);
+ }
+
+ unregister_syscore_ops(&ledtrig_cpu_syscore_ops);
+}
+module_exit(ledtrig_cpu_exit);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_AUTHOR("Bryan Wu <bryan.wu@canonical.com>");
+MODULE_DESCRIPTION("CPU LED trigger");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 39eee41d8c6f..cd545580e069 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -212,4 +212,20 @@ struct gpio_led_platform_data {
struct platform_device *gpio_led_register_device(
int id, const struct gpio_led_platform_data *pdata);
+enum cpu_led_event {
+ CPU_LED_IDLE_START, /* CPU enters idle */
+ CPU_LED_IDLE_END, /* CPU idle ends */
+ CPU_LED_START, /* Machine starts, especially resume */
+ CPU_LED_STOP, /* Machine stops, especially suspend */
+ CPU_LED_HALTED, /* Machine shutdown */
+};
+#ifdef CONFIG_LEDS_TRIGGER_CPU
+extern void ledtrig_cpu(enum cpu_led_event evt);
+#else
+static inline void ledtrig_cpu(enum cpu_led_event evt)
+{
+ return;
+}
+#endif
+
#endif /* __LINUX_LEDS_H_INCLUDED */