[PATCH 02/18] led-triggers: create a trigger for CPU activity

[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 at rpsys.net>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
Signed-off-by: Bryan Wu <bryan.wu at canonical.com>
---
 drivers/leds/Kconfig       |   10 ++++
 drivers/leds/Makefile      |    1 +
 drivers/leds/ledtrig-cpu.c |  120 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h       |   15 ++++++
 4 files changed, 146 insertions(+), 0 deletions(-)
 create mode 100644 drivers/leds/ledtrig-cpu.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index b591e72..a97c6a3 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -430,6 +430,16 @@ 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..d00ca77
--- /dev/null
+++ b/drivers/leds/ledtrig-cpu.c
@@ -0,0 +1,120 @@
+/*
+ * ledtrig-cpu.c - LED trigger based on CPU activity
+ *
+ * Copyright 2011 Linus Walleij <linus.walleij at linaro.org>
+ * Copyright 2011 Bryan Wu <bryan.wu at 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"
+
+static DEFINE_PER_CPU(struct led_trigger *, cpu_trig);
+static DEFINE_PER_CPU(char [8], trig_name);
+
+void ledtrig_cpu(enum cpu_led_event ledevt)
+{
+	struct led_trigger *trig = __get_cpu_var(cpu_trig);
+
+	if (!trig)
+		return;
+
+	/* 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, 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, LED_OFF);
+		break;
+
+	default:
+		/* Will leave the LED as it is */
+		break;
+	}
+}
+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 void __init ledtrig_cpu_register(void *info)
+{
+	int cpuid = smp_processor_id();
+	struct led_trigger *trig;
+	char *name = __get_cpu_var(trig_name);
+
+	snprintf(name, 8, "cpu%d", cpuid);
+	led_trigger_register_simple(name, &trig);
+
+	pr_info("LED trigger %s indicate activity on CPU %d\n",
+		trig->name, cpuid);
+
+	__get_cpu_var(cpu_trig) = trig;
+}
+
+static void __exit ledtrig_cpu_unregister(void *info)
+{
+	struct led_trigger *trig = __get_cpu_var(cpu_trig);
+	char *name = __get_cpu_var(trig_name);
+
+	led_trigger_unregister_simple(trig);
+	__get_cpu_var(cpu_trig) = NULL;
+	memset(name, 0, 8);
+}
+
+static int __init ledtrig_cpu_init(void)
+{
+	on_each_cpu(ledtrig_cpu_register, NULL, 1);
+	register_syscore_ops(&ledtrig_cpu_syscore_ops);
+
+	return 0;
+}
+module_init(ledtrig_cpu_init);
+
+static void __exit ledtrig_cpu_exit(void)
+{
+	on_each_cpu(ledtrig_cpu_unregister, NULL, 1);
+	unregister_syscore_ops(&ledtrig_cpu_syscore_ops);
+}
+module_exit(ledtrig_cpu_exit);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij at linaro.org>");
+MODULE_AUTHOR("Bryan Wu <bryan.wu at canonical.com>");
+MODULE_DESCRIPTION("CPU LED trigger");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 5884def..b782abd 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 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 */
+};
+
+/* Use this routine to handle LEDs */
+extern void ledtrig_cpu(enum cpu_led_event evt);
+#else
+#define ledtrig_cpu(evt) do {} while (0)
+#endif
+
 #endif		/* __LINUX_LEDS_H_INCLUDED */
-- 
1.7.5