Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / devfreq / governor_simpleondemand.c

diff --git a/kernel/drivers/devfreq/governor_simpleondemand.c b/kernel/drivers/devfreq/governor_simpleondemand.c
new file mode 100644 (file)
index 0000000..0720ba8
--- /dev/null
+++ b/kernel/drivers/devfreq/governor_simpleondemand.c
@@ -0,0 +1,147 @@
+/*
+ *  linux/drivers/devfreq/governor_simpleondemand.c
+ *
+ *  Copyright (C) 2011 Samsung Electronics
+ *     MyungJoo Ham <myungjoo.ham@samsung.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/errno.h>
+#include <linux/module.h>
+#include <linux/devfreq.h>
+#include <linux/math64.h>
+#include "governor.h"
+
+/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
+#define DFSO_UPTHRESHOLD       (90)
+#define DFSO_DOWNDIFFERENCTIAL (5)
+static int devfreq_simple_ondemand_func(struct devfreq *df,
+                                       unsigned long *freq)
+{
+       struct devfreq_dev_status stat;
+       int err = df->profile->get_dev_status(df->dev.parent, &stat);
+       unsigned long long a, b;
+       unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
+       unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
+       struct devfreq_simple_ondemand_data *data = df->data;
+       unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
+
+       if (err)
+               return err;
+
+       if (data) {
+               if (data->upthreshold)
+                       dfso_upthreshold = data->upthreshold;
+               if (data->downdifferential)
+                       dfso_downdifferential = data->downdifferential;
+       }
+       if (dfso_upthreshold > 100 ||
+           dfso_upthreshold < dfso_downdifferential)
+               return -EINVAL;
+
+       /* Assume MAX if it is going to be divided by zero */
+       if (stat.total_time == 0) {
+               *freq = max;
+               return 0;
+       }
+
+       /* Prevent overflow */
+       if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {
+               stat.busy_time >>= 7;
+               stat.total_time >>= 7;
+       }
+
+       /* Set MAX if it's busy enough */
+       if (stat.busy_time * 100 >
+           stat.total_time * dfso_upthreshold) {
+               *freq = max;
+               return 0;
+       }
+
+       /* Set MAX if we do not know the initial frequency */
+       if (stat.current_frequency == 0) {
+               *freq = max;
+               return 0;
+       }
+
+       /* Keep the current frequency */
+       if (stat.busy_time * 100 >
+           stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {
+               *freq = stat.current_frequency;
+               return 0;
+       }
+
+       /* Set the desired frequency based on the load */
+       a = stat.busy_time;
+       a *= stat.current_frequency;
+       b = div_u64(a, stat.total_time);
+       b *= 100;
+       b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
+       *freq = (unsigned long) b;
+
+       if (df->min_freq && *freq < df->min_freq)
+               *freq = df->min_freq;
+       if (df->max_freq && *freq > df->max_freq)
+               *freq = df->max_freq;
+
+       return 0;
+}
+
+static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
+                               unsigned int event, void *data)
+{
+       switch (event) {
+       case DEVFREQ_GOV_START:
+               devfreq_monitor_start(devfreq);
+               break;
+
+       case DEVFREQ_GOV_STOP:
+               devfreq_monitor_stop(devfreq);
+               break;
+
+       case DEVFREQ_GOV_INTERVAL:
+               devfreq_interval_update(devfreq, (unsigned int *)data);
+               break;
+
+       case DEVFREQ_GOV_SUSPEND:
+               devfreq_monitor_suspend(devfreq);
+               break;
+
+       case DEVFREQ_GOV_RESUME:
+               devfreq_monitor_resume(devfreq);
+               break;
+
+       default:
+               break;
+       }
+
+       return 0;
+}
+
+static struct devfreq_governor devfreq_simple_ondemand = {
+       .name = "simple_ondemand",
+       .get_target_freq = devfreq_simple_ondemand_func,
+       .event_handler = devfreq_simple_ondemand_handler,
+};
+
+static int __init devfreq_simple_ondemand_init(void)
+{
+       return devfreq_add_governor(&devfreq_simple_ondemand);
+}
+subsys_initcall(devfreq_simple_ondemand_init);
+
+static void __exit devfreq_simple_ondemand_exit(void)
+{
+       int ret;
+
+       ret = devfreq_remove_governor(&devfreq_simple_ondemand);
+       if (ret)
+               pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+       return;
+}
+module_exit(devfreq_simple_ondemand_exit);
+MODULE_LICENSE("GPL");