[PATCH] Create new LED trigger for CPU activity

[Thomas Tuttle <thinkinginbinary@gmail.com>]

This patch creates a new LED trigger that triggers whenever the CPU is
active.  It can be configured with module parameters to trigger on any
combination of user, nice, system, or iowait time, and defaults to
including user and system time but not nice or iowait time.  I've tested
it a bit, and it seems to work, but no guarantees.  It's diffed against
2.6.17-git25.

Signed-off-by: Thomas Tuttle <thinkinginbinary@gmail.com>

diff -udrN linux-2.6.17-git25/drivers/leds/Kconfig linux-2.6.17-git25-mine/drivers/leds/Kconfig
--- linux-2.6.17-git25/drivers/leds/Kconfig	2006-07-05 22:11:45.000000000 -0400
+++ linux-2.6.17-git25-mine/drivers/leds/Kconfig	2006-07-06 09:23:18.000000000 -0400
@@ -93,6 +93,13 @@
 	  This allows LEDs to be controlled by IDE disk activity.
 	  If unsure, say Y.
 
+config LEDS_TRIGGER_CPU
+	tristate "LED CPU Trigger"
+	depends LEDS_TRIGGERS
+	help
+	  This allows LEDs to be controlled by CPU activity.
+	  If unsure, say Y.
+
 config LEDS_TRIGGER_HEARTBEAT
 	tristate "LED Heartbeat Trigger"
 	depends LEDS_TRIGGERS
diff -udrN linux-2.6.17-git25/drivers/leds/ledtrig-cpu.c linux-2.6.17-git25-mine/drivers/leds/ledtrig-cpu.c
--- linux-2.6.17-git25/drivers/leds/ledtrig-cpu.c	1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.17-git25-mine/drivers/leds/ledtrig-cpu.c	2006-07-06 15:11:34.000000000 -0400
@@ -0,0 +1,146 @@
+/*
+ * LED CPU Activity Trigger, revision 3
+ *
+ * Copyright 2006 Thomas Tuttle
+ *
+ * Author: Thomas Tuttle <thinkinginbinary@gmail.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.
+ *
+ */
+
+/*
+ * ChangeLog:
+ *
+ * Revision 3 (2006/06/06):
+ *   Added module parameters to configure which time is counted as CPU
+ *     activity. (thanks to Andrew Morton)
+ *
+ * Revision 2 (2006/06/05):
+ *   Diffed against 2.6.17-git25 instead of 2.6.17.1.
+ *   Fixed several code style issues (thanks to Randy Dunlap)
+ *
+ * Revision 1 (2006/06/05):
+ *   Initial patch submitted.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/leds.h>
+#include <linux/kernel_stat.h>
+#include <asm/cputime.h>
+
+#define UPDATE_INTERVAL (5) /* delay between updates, in ms */
+
+/* This *would* be an enum, but I use them as the private data in the
+ * include_* module parameters, so they know which kind of time to 
+ * include or exclude. */
+
+#define NUM_TIME_TYPES 4
+
+static int USER   = 0;
+static int NICE   = 1;
+static int SYSTEM = 2;
+static int IOWAIT = 3;
+
+static int include_time[NUM_TIME_TYPES] = { 1, 0, 1, 0 };
+
+static void ledtrig_cpu_timerfunc(unsigned long data);
+
+DEFINE_LED_TRIGGER(ledtrig_cpu);
+static DEFINE_TIMER(ledtrig_cpu_timer, ledtrig_cpu_timerfunc, 0, 0);
+
+static cputime64_t cpu_usage(void)
+{
+	int i;
+	cputime64_t time = cputime64_zero;
+
+	for_each_possible_cpu(i) {
+		if (include_time[USER])
+			time = cputime64_add(time, kstat_cpu(i).cpustat.user);
+		if (include_time[NICE])
+			time = cputime64_add(time, kstat_cpu(i).cpustat.nice);
+		if (include_time[SYSTEM])
+			time = cputime64_add(time, kstat_cpu(i).cpustat.system);
+		if (include_time[IOWAIT])
+			time = cputime64_add(time, kstat_cpu(i).cpustat.iowait);
+	}
+
+	return time;
+}
+
+static enum led_brightness last_led_state;
+static cputime64_t last_cputime;
+
+static void ledtrig_cpu_timerfunc(unsigned long data)
+{
+	cputime64_t this_cputime = cpu_usage();
+	/* XXX: This assumes that cputime64_t can be subtracted.
+	 * Nobody has defined cputime64_sub, so I had to do this instead. */
+	cputime64_t used_cputime = this_cputime - last_cputime;
+	enum led_brightness led_state = (used_cputime > 0) ? LED_FULL : LED_OFF;
+	if (led_state != last_led_state)
+		led_trigger_event(ledtrig_cpu, led_state);
+	last_led_state = led_state;
+	last_cputime = cpu_usage();
+
+	mod_timer(&ledtrig_cpu_timer, jiffies + msecs_to_jiffies(UPDATE_INTERVAL));
+}
+
+static int __init ledtrig_cpu_init(void)
+{
+	led_trigger_register_simple("cpu", &ledtrig_cpu);
+	led_trigger_event(ledtrig_cpu, LED_OFF);
+	last_led_state = LED_OFF;
+	last_cputime = cpu_usage();
+	mod_timer(&ledtrig_cpu_timer, jiffies + msecs_to_jiffies(UPDATE_INTERVAL));
+	return 0;
+}
+
+static void __exit ledtrig_cpu_exit(void)
+{
+	del_timer_sync(&ledtrig_cpu_timer);
+	led_trigger_event(ledtrig_cpu, LED_OFF);
+	led_trigger_unregister_simple(ledtrig_cpu);
+}
+
+static int get_include_time(char *buffer, struct kernel_param *kp)
+{
+	int which_time = *((int*)kp->arg);
+	if ((which_time < 0) || (which_time >= NUM_TIME_TYPES))
+		return -EINVAL;
+	sprintf(buffer, "%d", include_time[which_time]);
+	return strlen(buffer);
+}
+
+static int set_include_time(const char *val, struct kernel_param *kp)
+{
+	int which_time = *((int*)kp->arg);
+	int new_value;
+	if ((which_time < 0) || (which_time >= NUM_TIME_TYPES))
+		return -EINVAL;
+	if (sscanf(val, "%d", &new_value) != 1)
+		return -EINVAL;
+	include_time[which_time] = new_value;
+	return 0;
+}
+
+module_param_call(include_user, set_include_time, get_include_time, &USER, 6);
+module_param_call(include_nice, set_include_time, get_include_time, &NICE, 6);
+module_param_call(include_system, set_include_time, get_include_time, &SYSTEM, 6);
+module_param_call(include_iowait, set_include_time, get_include_time, &IOWAIT, 6);
+
+MODULE_AUTHOR("Thomas Tuttle <thinkinginbinary@gmail.com>");
+MODULE_DESCRIPTION("LED CPU Activity Trigger");
+MODULE_PARM_DESC(include_user, "Include user time when measuring CPU activity");
+MODULE_PARM_DESC(include_nice, "Include nice time when measuring CPU activity");
+MODULE_PARM_DESC(include_system, "Include system time when measuring CPU activity");
+MODULE_PARM_DESC(include_iowait, "Include IO wait time when measuring CPU activity");
+MODULE_LICENSE("GPL");
+
+module_init(ledtrig_cpu_init);
+module_exit(ledtrig_cpu_exit);
diff -udrN linux-2.6.17-git25/drivers/leds/Makefile linux-2.6.17-git25-mine/drivers/leds/Makefile
--- linux-2.6.17-git25/drivers/leds/Makefile	2006-07-05 22:11:45.000000000 -0400
+++ linux-2.6.17-git25-mine/drivers/leds/Makefile	2006-07-05 22:40:52.000000000 -0400
@@ -16,4 +16,5 @@
 # LED Triggers
 obj-$(CONFIG_LEDS_TRIGGER_TIMER)	+= ledtrig-timer.o
 obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK)	+= ledtrig-ide-disk.o
+obj-$(CONFIG_LEDS_TRIGGER_CPU)		+= ledtrig-cpu.o
 obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT)	+= ledtrig-heartbeat.o

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