[PATCH 01/18] led-triggers: create a trigger for CPU activity

Bryan Wu bryan.wu at canonical.com
Fri Mar 30 07:58:16 EDT 2012 

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>

Reviewed-by: Jamie Iles <jamie at jamieiles.com>
Tested-by: Jochen Friedrich <jochen at scram.de>
---
 drivers/leds/Kconfig       |   10 +++
 drivers/leds/Makefile      |    1 +
 drivers/leds/ledtrig-cpu.c |  138 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h       |   23 +++++++
 4 files changed, 172 insertions(+), 0 deletions(-)
 create mode 100644 drivers/leds/ledtrig-cpu.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index ff4b8cf..cf02fb8 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -448,6 +448,16 @@ config LEDS_TRIGGER_BACKLIGHT
 
 	  If unsure, say N.
 
+config LEDS_TRIGGER_CPU
+	tristate "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 890481c..0a3d5ad 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -55,4 +55,5 @@ 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..d48c4b5
--- /dev/null
+++ b/drivers/leds/ledtrig-cpu.c
@@ -0,0 +1,138 @@
+/*
+ * 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 binded with any LEDs as other triggers does, either in 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 at linaro.org>
+ * Copyright 2011 - 2012 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"
+
+#define MAX_NAME_LEN	8
+
+static DEFINE_PER_CPU(struct led_trigger *, cpu_trig);
+static DEFINE_PER_CPU(char [MAX_NAME_LEN], 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)
+{
+	int cpuid = smp_processor_id();
+	struct led_trigger *trig;
+	char *name = __get_cpu_var(trig_name);
+
+	snprintf(name, MAX_NAME_LEN, "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)
+{
+	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, MAX_NAME_LEN);
+}
+
+static int __init ledtrig_cpu_init(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		ledtrig_cpu_register();
+
+	register_syscore_ops(&ledtrig_cpu_syscore_ops);
+
+	return 0;
+}
+module_init(ledtrig_cpu_init);
+
+static void __exit ledtrig_cpu_exit(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		ledtrig_cpu_unregister();
+
+	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..1215b94 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -210,4 +210,27 @@ 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 */
+};
+#if defined(CONFIG_LEDS_TRIGGER_CPU) || defined(CONFIG_LEDS_TRIGGER_CPU_MODULE)
+/**
+ * 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.
+ */
+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 */
-- 
1.7.9.1

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