PM / devfreq: Add cache HW monitor governor

This is a snapshot of the HW monitor governor driver as of msm-3.10
commit:

acdce027751d5a7488b283f0ce3111f873a5816d (Merge "defconfig: arm64:
Enable ONESHOT_SYNC for msm8994")

Signed-off-by: Kumar Gala <galak@codeaurora.org>

4 files changed, 380 insertions, 0 deletions

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index c547184fac53..cd451af43984 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -72,6 +72,16 @@ config DEVFREQ_GOV_QCOM_ADRENO_TZ
 	  Sets the frequency using a "on-demand" algorithm.
 	  This governor is unlikely to be useful for other devices.
 
+config DEVFREQ_GOV_MSM_CACHE_HWMON
+	tristate "HW monitor based governor for cache frequency"
+	help
+	  HW monitor based governor for cache frequency scaling. This
+	  governor currently supports only Krait L2 PM counters.  Sets the
+	  cache frequency by using L2 PM counters to monitor the Krait's use
+	  of the L2.  Since this governor uses some of the PM counters it can
+	  conflict with existing profiling tools.  This governor is unlikely
+	  to be useful for other devices.
+
 comment "DEVFREQ Drivers"
 
 config ARM_EXYNOS4_BUS_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index ebe328713e5d..862083911ef2 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE)	+= governor_performance.o
 obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE)	+= governor_powersave.o
 obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
 obj-$(CONFIG_DEVFREQ_GOV_QCOM_ADRENO_TZ) += governor_msm_adreno_tz.o
+obj-$(CONFIG_DEVFREQ_GOV_MSM_CACHE_HWMON)	+= governor_cache_hwmon.o
 
 # DEVFREQ Drivers
 obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)	+= exynos/
diff --git a/drivers/devfreq/governor_cache_hwmon.c b/drivers/devfreq/governor_cache_hwmon.c
new file mode 100644
index 000000000000..3fff31aff6c7
--- /dev/null
+++ b/drivers/devfreq/governor_cache_hwmon.c
@@ -0,0 +1,323 @@
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "cache-hwmon: " fmt
+
+#include <linux/kernel.h>
+#include <linux/sizes.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/ktime.h>
+#include <linux/time.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/devfreq.h>
+#include "governor.h"
+#include "governor_cache_hwmon.h"
+
+#define show_attr(name) \
+static ssize_t show_##name(struct device *dev,				\
+			struct device_attribute *attr, char *buf)	\
+{									\
+	return snprintf(buf, PAGE_SIZE, "%u\n", name);			\
+}
+
+#define store_attr(name, _min, _max) \
+static ssize_t store_##name(struct device *dev,				\
+			struct device_attribute *attr, const char *buf,	\
+			size_t count)					\
+{									\
+	int ret;							\
+	unsigned int val;						\
+	ret = sscanf(buf, "%u", &val);					\
+	if (ret != 1)							\
+		return -EINVAL;						\
+	val = max(val, _min);						\
+	val = min(val, _max);						\
+	name = val;							\
+	return count;							\
+}
+
+#define gov_attr(__attr, min, max)	\
+show_attr(__attr)			\
+store_attr(__attr, min, max)		\
+static DEVICE_ATTR(__attr, 0644, show_##__attr, store_##__attr)
+
+
+static struct cache_hwmon *hw;
+static unsigned int cycles_per_low_req;
+static unsigned int cycles_per_med_req = 20;
+static unsigned int cycles_per_high_req = 35;
+static unsigned int min_busy = 100;
+static unsigned int max_busy = 100;
+static unsigned int tolerance_mrps = 5;
+static unsigned int guard_band_mhz = 100;
+static unsigned int decay_rate = 90;
+
+#define MIN_MS	10U
+#define MAX_MS	500U
+static unsigned int sample_ms = 50;
+static unsigned long prev_mhz;
+static ktime_t prev_ts;
+
+static unsigned long measure_mrps_and_set_irq(struct devfreq *df,
+			struct mrps_stats *stat)
+{
+	ktime_t ts;
+	unsigned int us;
+
+	/*
+	 * Since we are stopping the counters, we don't want this short work
+	 * to be interrupted by other tasks and cause the measurements to be
+	 * wrong. Not blocking interrupts to avoid affecting interrupt
+	 * latency and since they should be short anyway because they run in
+	 * atomic context.
+	 */
+	preempt_disable();
+
+	ts = ktime_get();
+	us = ktime_to_us(ktime_sub(ts, prev_ts));
+	if (!us)
+		us = 1;
+
+	hw->meas_mrps_and_set_irq(df, tolerance_mrps, us, stat);
+	prev_ts = ts;
+
+	preempt_enable();
+
+	pr_debug("stat H=%3lu, M=%3lu, T=%3lu, b=%3u, f=%4lu, us=%d\n",
+		 stat->high, stat->med, stat->high + stat->med,
+		 stat->busy_percent, df->previous_freq / 1000, us);
+
+	return 0;
+}
+
+static void compute_cache_freq(struct mrps_stats *mrps, unsigned long *freq)
+{
+	unsigned long new_mhz;
+	unsigned int busy;
+
+	new_mhz = mrps->high * cycles_per_high_req
+		+ mrps->med * cycles_per_med_req
+		+ mrps->low * cycles_per_low_req;
+
+	busy = max(min_busy, mrps->busy_percent);
+	busy = min(max_busy, busy);
+
+	new_mhz *= 100;
+	new_mhz /= busy;
+
+	if (new_mhz < prev_mhz) {
+		new_mhz = new_mhz * decay_rate + prev_mhz * (100 - decay_rate);
+		new_mhz /= 100;
+	}
+	prev_mhz = new_mhz;
+
+	new_mhz += guard_band_mhz;
+	*freq = new_mhz * 1000;
+}
+
+#define TOO_SOON_US	(1 * USEC_PER_MSEC)
+static irqreturn_t mon_intr_handler(int irq, void *dev)
+{
+	struct devfreq *df = dev;
+	ktime_t ts;
+	unsigned int us;
+	int ret;
+
+	if (!hw->is_valid_irq(df))
+		return IRQ_NONE;
+
+	pr_debug("Got interrupt\n");
+	devfreq_monitor_stop(df);
+
+	/*
+	 * Don't recalc cache freq if the interrupt comes right after a
+	 * previous cache freq calculation.  This is done for two reasons:
+	 *
+	 * 1. Sampling the cache request during a very short duration can
+	 *    result in a very inaccurate measurement due to very short
+	 *    bursts.
+	 * 2. This can only happen if the limit was hit very close to the end
+	 *    of the previous sample period. Which means the current cache
+	 *    request estimate is not very off and doesn't need to be
+	 *    readjusted.
+	 */
+	ts = ktime_get();
+	us = ktime_to_us(ktime_sub(ts, prev_ts));
+	if (us > TOO_SOON_US) {
+		mutex_lock(&df->lock);
+		ret = update_devfreq(df);
+		if (ret)
+			pr_err("Unable to update freq on IRQ!\n");
+		mutex_unlock(&df->lock);
+	}
+
+	devfreq_monitor_start(df);
+
+	return IRQ_HANDLED;
+}
+
+static int devfreq_cache_hwmon_get_freq(struct devfreq *df,
+					unsigned long *freq,
+					u32 *flag)
+{
+	struct mrps_stats stat;
+
+	measure_mrps_and_set_irq(df, &stat);
+	compute_cache_freq(&stat, freq);
+
+	return 0;
+}
+
+gov_attr(cycles_per_low_req, 1U, 100U);
+gov_attr(cycles_per_med_req, 1U, 100U);
+gov_attr(cycles_per_high_req, 1U, 100U);
+gov_attr(min_busy, 1U, 100U);
+gov_attr(max_busy, 1U, 100U);
+gov_attr(tolerance_mrps, 0U, 100U);
+gov_attr(guard_band_mhz, 0U, 500U);
+gov_attr(decay_rate, 0U, 100U);
+
+static struct attribute *dev_attr[] = {
+	&dev_attr_cycles_per_low_req.attr,
+	&dev_attr_cycles_per_med_req.attr,
+	&dev_attr_cycles_per_high_req.attr,
+	&dev_attr_min_busy.attr,
+	&dev_attr_max_busy.attr,
+	&dev_attr_tolerance_mrps.attr,
+	&dev_attr_guard_band_mhz.attr,
+	&dev_attr_decay_rate.attr,
+	NULL,
+};
+
+static struct attribute_group dev_attr_group = {
+	.name = "cache_hwmon",
+	.attrs = dev_attr,
+};
+
+static int start_monitoring(struct devfreq *df)
+{
+	int ret;
+	struct mrps_stats mrps;
+
+	prev_ts = ktime_get();
+	prev_mhz = 0;
+	mrps.high = (df->previous_freq / 1000) - guard_band_mhz;
+	mrps.high /= cycles_per_high_req;
+
+	ret = hw->start_hwmon(df, &mrps);
+	if (ret) {
+		pr_err("Unable to start HW monitor!\n");
+		return ret;
+	}
+
+	devfreq_monitor_start(df);
+
+	ret = request_threaded_irq(hw->irq, NULL, mon_intr_handler,
+			  IRQF_ONESHOT | IRQF_SHARED,
+			  "cache_hwmon", df);
+	if (ret) {
+		pr_err("Unable to register interrupt handler!\n");
+		goto req_irq_fail;
+	}
+
+	ret = sysfs_create_group(&df->dev.kobj, &dev_attr_group);
+	if (ret) {
+		pr_err("Error creating sys entries!\n");
+		goto sysfs_fail;
+	}
+
+	return 0;
+
+sysfs_fail:
+	disable_irq(hw->irq);
+	free_irq(hw->irq, df);
+req_irq_fail:
+	devfreq_monitor_stop(df);
+	hw->stop_hwmon(df);
+	return ret;
+}
+
+static void stop_monitoring(struct devfreq *df)
+{
+	sysfs_remove_group(&df->dev.kobj, &dev_attr_group);
+	disable_irq(hw->irq);
+	free_irq(hw->irq, df);
+	devfreq_monitor_stop(df);
+	hw->stop_hwmon(df);
+}
+
+static int devfreq_cache_hwmon_ev_handler(struct devfreq *df,
+					unsigned int event, void *data)
+{
+	int ret;
+
+	switch (event) {
+	case DEVFREQ_GOV_START:
+		sample_ms = df->profile->polling_ms;
+		sample_ms = max(MIN_MS, sample_ms);
+		sample_ms = min(MAX_MS, sample_ms);
+		df->profile->polling_ms = sample_ms;
+
+		ret = start_monitoring(df);
+		if (ret)
+			return ret;
+
+		pr_debug("Enabled Cache HW monitor governor\n");
+		break;
+
+	case DEVFREQ_GOV_STOP:
+		stop_monitoring(df);
+		pr_debug("Disabled Cache HW monitor governor\n");
+		break;
+
+	case DEVFREQ_GOV_INTERVAL:
+		sample_ms = *(unsigned int *)data;
+		sample_ms = max(MIN_MS, sample_ms);
+		sample_ms = min(MAX_MS, sample_ms);
+		devfreq_interval_update(df, &sample_ms);
+		break;
+	}
+
+	return 0;
+}
+
+static struct devfreq_governor devfreq_cache_hwmon = {
+	.name = "cache_hwmon",
+	.get_target_freq = devfreq_cache_hwmon_get_freq,
+	.event_handler = devfreq_cache_hwmon_ev_handler,
+};
+
+int register_cache_hwmon(struct cache_hwmon *hwmon)
+{
+	int ret;
+
+	hw = hwmon;
+	ret = devfreq_add_governor(&devfreq_cache_hwmon);
+	if (ret) {
+		pr_err("devfreq governor registration failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+MODULE_DESCRIPTION("HW monitor based cache freq driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/devfreq/governor_cache_hwmon.h b/drivers/devfreq/governor_cache_hwmon.h
new file mode 100644
index 000000000000..5361894e201a
--- /dev/null
+++ b/drivers/devfreq/governor_cache_hwmon.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _GOVERNOR_CACHE_HWMON_H
+#define _GOVERNOR_CACHE_HWMON_H
+
+#include <linux/kernel.h>
+#include <linux/devfreq.h>
+
+struct mrps_stats {
+	unsigned long high;
+	unsigned long med;
+	unsigned long low;
+	unsigned int busy_percent;
+};
+
+struct cache_hwmon {
+	int (*start_hwmon)(struct devfreq *df, struct mrps_stats *mrps);
+	void (*stop_hwmon)(struct devfreq *df);
+	bool (*is_valid_irq)(struct devfreq *df);
+	unsigned long (*meas_mrps_and_set_irq)(struct devfreq *df,
+					unsigned int tol, unsigned int us,
+					struct mrps_stats *mrps);
+	int irq;
+};
+
+#ifdef CONFIG_DEVFREQ_GOV_MSM_CACHE_HWMON
+int register_cache_hwmon(struct cache_hwmon *hwmon);
+#else
+static inline int register_cache_hwmon(struct cache_hwmon *hwmon)
+{
+	return 0;
+}
+#endif
+
+#endif /* _GOVERNOR_CACHE_HWMON_H */