[PATCH 1/4] leds: create a trigger for CPU activity

[bryan.wu@canonical.com (Bryan Wu)]

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 at canonical.com:
It moves arch/arm/kernel/leds.c 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>
---
 drivers/leds/Kconfig       |   10 +++
 drivers/leds/Makefile      |    1 +
 drivers/leds/ledtrig-cpu.c |  145 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h       |   15 +++++
 4 files changed, 171 insertions(+), 0 deletions(-)
 create mode 100644 drivers/leds/ledtrig-cpu.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 713d43b..186000a 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -446,6 +446,16 @@ 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 what
+	  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 bbfd2e3..5e70d2e 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -53,4 +53,5 @@ 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
diff --git a/drivers/leds/ledtrig-cpu.c b/drivers/leds/ledtrig-cpu.c
new file mode 100644
index 0000000..b0a89fd
--- /dev/null
+++ b/drivers/leds/ledtrig-cpu.c
@@ -0,0 +1,145 @@
+/*
+ * ledtrig-cpu.c - LED trigger based on CPU activity
+ *
+ * Copyright 2011 Linus Walleij <linus.walleij@linaro.org>
+ * Copyright 2011 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 "leds.h"
+
+struct cpu_trig_data {
+	struct led_classdev *led;
+};
+
+static DEFINE_PER_CPU(struct cpu_trig_data *, cpu_triggers);
+
+void ledtrig_cpu(enum cpu_led_event ledevt)
+{
+	struct cpu_trig_data *trigdata = __get_cpu_var(cpu_triggers);
+
+	if (!trigdata)
+		return;
+
+	/* Locate the correct CPU LED */
+
+	switch (ledevt) {
+	case CPU_LED_START:
+	case CPU_LED_IDLE_START:
+		/* Will turn the LED on, max brightness */
+		if (trigdata->led)
+			led_set_brightness(trigdata->led,
+					   trigdata->led->max_brightness);
+		break;
+
+	case CPU_LED_STOP:
+	case CPU_LED_IDLE_END:
+	case CPU_LED_HALTED:
+		/* Will turn the LED off */
+		if (trigdata->led)
+			led_set_brightness(trigdata->led, LED_OFF);
+		break;
+
+	default:
+		/* Will leave the LED as it is */
+		break;
+	}
+}
+EXPORT_SYMBOL(ledtrig_cpu);
+
+static void cpu_trig_activate_cpu(void *data)
+{
+	struct cpu_trig_data *cpu_data;
+	struct led_classdev *led = data;
+	int my_cpu = smp_processor_id();
+	unsigned long target_cpu = (unsigned long) led->trigger_data;
+
+	if (target_cpu != my_cpu)
+		return;
+
+	cpu_data = kzalloc(sizeof(*cpu_data), GFP_KERNEL);
+	if (!cpu_data)
+		return;
+
+	dev_info(led->dev, "led %s indicate activity on CPU %d\n",
+		 led->name, my_cpu);
+
+	cpu_data->led = led;
+	__get_cpu_var(cpu_triggers) = cpu_data;
+}
+
+static void cpu_trig_activate(struct led_classdev *led)
+{
+	on_each_cpu(cpu_trig_activate_cpu, led, 1);
+}
+
+static void cpu_trig_deactivate(struct led_classdev *led)
+{
+	struct cpu_trig_data *cpu_data = led->trigger_data;
+
+	if (cpu_data)
+		kfree(cpu_data);
+}
+
+static struct led_trigger cpu_led_trigger = {
+	.name		= "cpu",
+	.activate	= cpu_trig_activate,
+	.deactivate	= cpu_trig_deactivate,
+};
+
+
+static int cpu_syscore_suspend(void)
+{
+	ledtrig_cpu(CPU_LED_STOP);
+	return 0;
+}
+
+static void cpu_syscore_resume(void)
+{
+	ledtrig_cpu(CPU_LED_START);
+}
+
+static void cpu_syscore_shutdown(void)
+{
+	ledtrig_cpu(CPU_LED_HALTED);
+}
+
+static struct syscore_ops cpu_syscore_ops = {
+	.shutdown	= cpu_syscore_shutdown,
+	.suspend	= cpu_syscore_suspend,
+	.resume		= cpu_syscore_resume,
+};
+
+static int __init cpu_trig_init(void)
+{
+	int ret;
+
+	ret = led_trigger_register(&cpu_led_trigger);
+	if (!ret)
+		register_syscore_ops(&cpu_syscore_ops);
+
+	return ret;
+}
+module_init(cpu_trig_init);
+
+static void __exit cpu_trig_exit(void)
+{
+	unregister_syscore_ops(&cpu_syscore_ops);
+	led_trigger_unregister(&cpu_led_trigger);
+}
+module_exit(cpu_trig_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 5884def..d9e0ebc 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -210,4 +210,19 @@ struct gpio_led_platform_data {
 struct platform_device *gpio_led_register_device(
 		int id, const struct gpio_led_platform_data *pdata);
 
+#ifdef CONFIG_LEDS_TRIGGER_CPU
+enum cpu_led_event {
+	CPU_LED_IDLE_START,
+	CPU_LED_IDLE_END,
+	CPU_LED_START,
+	CPU_LED_STOP,
+	CPU_LED_HALTED
+};
+
+/* Use this routine to handle LEDs */
+extern void ledtrig_cpu(enum cpu_led_event evt);
+#else
+#define ledtrig_cpu() do {} while(0)
+#endif
+
 #endif		/* __LINUX_LEDS_H_INCLUDED */
-- 
1.7.4.1