3 files changed, 174 insertions, 0 deletions

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index c96bbaadeebd..16578d3b52bb 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -506,6 +506,16 @@ 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 a4429a9217bc..a9b627c4f8ba 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -61,5 +61,6 @@ 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");