led-triggers: create a trigger for CPU activity
Bryan Wu [Sat, 25 Jun 2011 10:33:50 +0000 (18:33 +0800)]
Attempting to consolidate the ARM LED code, this removes the
custom RealView LED trigger code to turn LEDs on and off in
response to CPU activity and replace it with a standard trigger.

(bryan.wu@canonical.com:
It introduces several syscore stubs into this trigger.
It also provides ledtrig_cpu trigger event stub in <linux/leds.h>.
Although it was inspired by ARM work, it can be used in other arch.)

Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>
Reviewed-by: Jamie Iles <jamie@jamieiles.com>
Tested-by: Jochen Friedrich <jochen@scram.de>

drivers/leds/Kconfig
drivers/leds/Makefile
drivers/leds/ledtrig-cpu.c [new file with mode: 0644]
include/linux/leds.h

index 12b2b55..c96fd29 100644 (file)
@@ -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
index f8958cd..fa0f536 100644 (file)
@@ -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 (file)
index 0000000..b312056
--- /dev/null
@@ -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");
index 39eee41..cd54558 100644 (file)
@@ -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 */