[PATCH v2 0/3] Add support for Tegra Activity Monitor

[PATCH v2 0/3] Add support for Tegra Activity Monitor

[Tomeu Vizoso]

Hello,

in this v2 I have made the driver use devfreq. It works just as fine as the
previous revision, but it's almost 200 lines more of code for not that much
gain.

Though I don't see much point in using devfreq, I think it's probably better
than an ad-hoc driver because in the future I hope that devfreq will gain
functionality that will be of use (PM_QOS_MEMORY_BANDWIDTH support, for
example).

These patches implement support for setting the rate of the EMC clock based on
stats collected from the ACTMON, a piece of hw in the Tegra124 that counts
memory accesses (among others).

It depends on the following in-flight patches:

* EMC driver: http://thread.gmane.org/gmane.linux.drivers.devicetree/99304
* CPUFreq driver: http://thread.gmane.org/gmane.linux.kernel/1812962

I have pushed a branch here for testing:

http://cgit.collabora.com/git/user/tomeu/linux.git/log/?h=actmon-v2

Regards,

Tomeu

Tomeu Vizoso (3):
  of: Add binding for NVIDIA Tegra ACTMON node
  PM / devfreq: tegra: add devfreq driver for Tegra Activity Monitor
  ARM: tegra: Add Tegra124 ACTMON support

 .../devicetree/bindings/arm/tegra/actmon.txt       |  38 ++
 arch/arm/boot/dts/tegra124.dtsi                    |  23 +
 drivers/devfreq/Kconfig                            |  10 +
 drivers/devfreq/Makefile                           |   1 +
 drivers/devfreq/tegra-devfreq.c                    | 718 +++++++++++++++++++++
 5 files changed, 790 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/tegra/actmon.txt
 create mode 100644 drivers/devfreq/tegra-devfreq.c

-- 
1.9.3

[PATCH v2 1/3] of: Add binding for NVIDIA Tegra ACTMON node

[Tomeu Vizoso]

This block gathers statistics about various counters and can be configured to
fire interrupts when thresholds are crossed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>

---

v2:	* Add operating-points property
---
 .../devicetree/bindings/arm/tegra/actmon.txt       | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/tegra/actmon.txt

diff --git a/Documentation/devicetree/bindings/arm/tegra/actmon.txt b/Documentation/devicetree/bindings/arm/tegra/actmon.txt
new file mode 100644
index 0000000..b4069df
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/tegra/actmon.txt
@@ -0,0 +1,38 @@
+Tegra124 Activity Monitor driver
+
+Required properties:
+
+- compatible: should be "nvidia,tegra124-actmon"
+- reg: offset and length of the register set for the device
+- interrupts: standard interrupt property
+- clocks: Must contain a phandle and clock specifier pair for each entry in clock-names. See ../clock/clock-bindings.txt for details.
+- clock-names: Must include the following entries:
+  - actmon
+  - emc
+- resets: Must contain an entry for each entry in reset-names. See ../reset/reset.txt for details.
+- reset-names: Must include the following entries:
+  - actmon
+- operating-points: Supported operating points. See ../power/opp.txt for details.
+
+Example:
+	actmon@6000c800 {
+		compatible = "nvidia,tegra124-actmon";
+		reg = <0x0 0x6000c800 0x0 0x400>;
+		interrupts = <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&tegra_car TEGRA124_CLK_ACTMON>,
+			 <&tegra_car TEGRA124_CLK_EMC>;
+		clock-names = "actmon", "emc";
+		resets = <&tegra_car 119>;
+		reset-names = "actmon";
+		operating-points = <
+			/* kHz	uV */
+			102000	800000
+			204000	800000
+			300000	820000
+			396000	850000
+			528000	880000
+			600000	910000
+			792000	980000
+			924000	1010000
+		>;
+	};
-- 
1.9.3

[PATCH v2 2/3] PM / devfreq: tegra: add devfreq driver for Tegra Activity Monitor

[Tomeu Vizoso]

The ACTMON block can monitor several counters, providing averaging and firing
interrupts based on watermarking configuration. This implementation monitors
the MCALL and MCCPU counters to choose an appropriate frequency for the
external memory clock.

This patch is based on work by Alex Frid <afrid@nvidia.com> and Mikko
Perttunen <mikko.perttunen@kapsi.fi>.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>

---

v2:	* Use devfreq
---
 drivers/devfreq/Kconfig         |  10 +
 drivers/devfreq/Makefile        |   1 +
 drivers/devfreq/tegra-devfreq.c | 718 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 729 insertions(+)
 create mode 100644 drivers/devfreq/tegra-devfreq.c

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index faf4e70..4aab799 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -87,4 +87,14 @@ config ARM_EXYNOS5_BUS_DEVFREQ
 	  It reads PPMU counters of memory controllers and adjusts the
 	  operating frequencies and voltages with OPP support.
 
+config ARM_TEGRA_DEVFREQ
+       tristate "Tegra DEVFREQ Driver"
+       depends on ARCH_TEGRA_124_SOC
+       select DEVFREQ_GOV_SIMPLE_ONDEMAND
+       select PM_OPP
+       help
+         This adds the DEVFREQ driver for the Tegra family of SoCs.
+         It reads ACTMON counters of memory controllers and adjusts the
+         operating frequencies and voltages with OPP support.
+
 endif # PM_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 16138c9..0ea991f 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
 # DEVFREQ Drivers
 obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)	+= exynos/
 obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)	+= exynos/
+obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
new file mode 100644
index 0000000..3479096
--- /dev/null
+++ b/drivers/devfreq/tegra-devfreq.c
@@ -0,0 +1,718 @@
+/*
+ * A devfreq driver for NVIDIA Tegra SoCs
+ *
+ * Copyright (c) 2014 NVIDIA CORPORATION. All rights reserved.
+ * Copyright (C) 2014 Google, Inc
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/cpufreq.h>
+#include <linux/devfreq.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/reset.h>
+
+#include "governor.h"
+
+#define ACTMON_GLB_STATUS					0x0
+#define ACTMON_GLB_PERIOD_CTRL					0x4
+
+#define ACTMON_DEV_CTRL						0x0
+#define ACTMON_DEV_CTRL_K_VAL_SHIFT				10
+#define ACTMON_DEV_CTRL_ENB_PERIODIC				BIT(18)
+#define ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN			BIT(20)
+#define ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN			BIT(21)
+#define ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT	23
+#define ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT	26
+#define ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN		BIT(29)
+#define ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN		BIT(30)
+#define ACTMON_DEV_CTRL_ENB					BIT(31)
+
+#define ACTMON_DEV_UPPER_WMARK					0x4
+#define ACTMON_DEV_LOWER_WMARK					0x8
+#define ACTMON_DEV_INIT_AVG					0xc
+#define ACTMON_DEV_AVG_UPPER_WMARK				0x10
+#define ACTMON_DEV_AVG_LOWER_WMARK				0x14
+#define ACTMON_DEV_COUNT_WEIGHT					0x18
+#define ACTMON_DEV_AVG_COUNT					0x20
+#define ACTMON_DEV_INTR_STATUS					0x24
+
+#define ACTMON_INTR_STATUS_CLEAR				0xffffffff
+
+#define ACTMON_DEV_INTR_CONSECUTIVE_UPPER			BIT(31)
+#define ACTMON_DEV_INTR_CONSECUTIVE_LOWER			BIT(30)
+
+#define ACTMON_ABOVE_WMARK_WINDOW				1
+#define ACTMON_BELOW_WMARK_WINDOW				3
+#define ACTMON_BOOST_FREQ_STEP					16000
+
+/* activity counter is incremented every 256 memory transactions, and each
+ * transaction takes 4 EMC clocks for Tegra124; So the COUNT_WEIGHT is
+ * 4 * 256 = 1024.
+ */
+#define ACTMON_COUNT_WEIGHT					0x400
+
+/*
+ * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which
+ * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128
+ */
+#define ACTMON_AVERAGE_WINDOW_LOG2			6
+#define ACTMON_SAMPLING_PERIOD				12 /* ms */
+#define ACTMON_DEFAULT_AVG_BAND				6  /* 1/10 of % */
+
+#define KHZ							1000
+
+/* Assume that the bus is saturated if the utilization is 25% */
+#define BUS_SATURATION_RATIO					25
+
+/**
+ * struct tegra_devfreq_device_config - configuration specific to an ACTMON
+ * device
+ *
+ * Coefficients and thresholds are in %
+ */
+struct tegra_devfreq_device_config {
+	u32		offset;
+	u32		irq_mask;
+
+	unsigned int	boost_up_coeff;
+	unsigned int	boost_down_coeff;
+	unsigned int	boost_up_threshold;
+	unsigned int	boost_down_threshold;
+	u32		avg_dependency_threshold;
+};
+
+enum tegra_actmon_device {
+	MCALL = 0,
+	MCCPU,
+};
+
+static struct tegra_devfreq_device_config actmon_device_configs[] = {
+	{
+		/* MCALL */
+		.offset = 0x1c0,
+		.irq_mask = 1 << 26,
+		.boost_up_coeff = 200,
+		.boost_down_coeff = 50,
+		.boost_up_threshold = 60,
+		.boost_down_threshold = 40,
+	},
+	{
+		/* MCCPU */
+		.offset = 0x200,
+		.irq_mask = 1 << 25,
+		.boost_up_coeff = 800,
+		.boost_down_coeff = 90,
+		.boost_up_threshold = 27,
+		.boost_down_threshold = 10,
+		.avg_dependency_threshold = 50000,
+	},
+};
+
+/**
+ * struct tegra_devfreq_device - state specific to an ACTMON device
+ *
+ * Frequencies are in kHz.
+ */
+struct tegra_devfreq_device {
+	const struct tegra_devfreq_device_config *config;
+
+	void __iomem	*regs;
+	u32		avg_band_freq;
+	u32		avg_count;
+
+	unsigned long	target_freq;
+	unsigned long	boost_freq;
+};
+
+struct tegra_devfreq {
+	struct devfreq		*devfreq;
+
+	struct platform_device	*pdev;
+	struct reset_control	*reset;
+	struct clk		*clock;
+	void __iomem		*regs;
+
+	spinlock_t		lock;
+
+	struct clk		*emc_clock;
+	unsigned long		max_freq;
+	unsigned long		cur_freq;
+	struct notifier_block	rate_change_nb;
+
+	struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
+};
+
+struct tegra_actmon_emc_ratio {
+	unsigned long cpu_freq;
+	unsigned long emc_freq;
+};
+
+static struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
+	{ 1400000, ULONG_MAX },
+	{ 1200000,    750000 },
+	{ 1100000,    600000 },
+	{ 1000000,    500000 },
+	{  800000,    375000 },
+	{  500000,    200000 },
+	{  250000,    100000 },
+};
+
+static unsigned long do_percent(unsigned long val, unsigned int pct)
+{
+	return val * pct / 100;
+}
+
+static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq_device *dev)
+{
+	u32 avg = dev->avg_count;
+	u32 band = dev->avg_band_freq * ACTMON_SAMPLING_PERIOD;
+
+	writel(avg + band, dev->regs + ACTMON_DEV_AVG_UPPER_WMARK);
+	avg = max(avg, band);
+	writel(avg - band, dev->regs + ACTMON_DEV_AVG_LOWER_WMARK);
+}
+
+static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
+				       struct tegra_devfreq_device *dev)
+{
+	u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
+
+	writel(do_percent(val, dev->config->boost_up_threshold),
+	       dev->regs + ACTMON_DEV_UPPER_WMARK);
+
+	writel(do_percent(val, dev->config->boost_down_threshold),
+	       dev->regs + ACTMON_DEV_LOWER_WMARK);
+}
+
+static void actmon_write_barrier(struct tegra_devfreq *tegra)
+{
+	/* ensure the update has reached the ACTMON */
+	wmb();
+	readl(tegra->regs + ACTMON_GLB_STATUS);
+}
+
+static irqreturn_t actmon_isr(int irq, void *data)
+{
+	struct tegra_devfreq *tegra = data;
+	struct tegra_devfreq_device *dev = NULL;
+	unsigned long flags;
+	u32 val;
+	unsigned int i;
+
+	val = readl(tegra->regs + ACTMON_GLB_STATUS);
+
+	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
+		if (val & tegra->devices[i].config->irq_mask) {
+			dev = tegra->devices + i;
+			break;
+		}
+	}
+
+	if (!dev)
+		return IRQ_NONE;
+
+	spin_lock_irqsave(&tegra->lock, flags);
+
+	dev->avg_count = readl(dev->regs + ACTMON_DEV_AVG_COUNT);
+	tegra_devfreq_update_avg_wmark(dev);
+
+	val = readl(dev->regs + ACTMON_DEV_INTR_STATUS);
+	if (val & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) {
+		val = readl(dev->regs + ACTMON_DEV_CTRL) |
+			ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN |
+			ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
+
+		/*
+		 * new_boost = min(old_boost * up_coef + step, max_freq)
+		 */
+		dev->boost_freq = do_percent(dev->boost_freq,
+					     dev->config->boost_up_coeff);
+		dev->boost_freq += ACTMON_BOOST_FREQ_STEP;
+		if (dev->boost_freq >= tegra->max_freq) {
+			dev->boost_freq = tegra->max_freq;
+			val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
+		}
+		writel(val, dev->regs + ACTMON_DEV_CTRL);
+	} else if (val & ACTMON_DEV_INTR_CONSECUTIVE_LOWER) {
+		val = readl(dev->regs + ACTMON_DEV_CTRL) |
+			ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN |
+			ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
+
+		/*
+		 * new_boost = old_boost * down_coef
+		 * or 0 if (old_boost * down_coef < step / 2)
+		 */
+		dev->boost_freq = do_percent(dev->boost_freq,
+					     dev->config->boost_down_coeff);
+		if (dev->boost_freq < (ACTMON_BOOST_FREQ_STEP >> 1)) {
+			dev->boost_freq = 0;
+			val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
+		}
+		writel(val, dev->regs + ACTMON_DEV_CTRL);
+	}
+
+	if (dev->config->avg_dependency_threshold) {
+		val = readl(dev->regs + ACTMON_DEV_CTRL);
+		if (dev->avg_count >= dev->config->avg_dependency_threshold)
+			val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
+		else if (dev->boost_freq == 0)
+			val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
+		writel(val, dev->regs + ACTMON_DEV_CTRL);
+	}
+
+	writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
+
+	actmon_write_barrier(tegra);
+
+	spin_unlock_irqrestore(&tegra->lock, flags);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
+					    unsigned long cpu_freq)
+{
+	unsigned int i;
+	struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
+
+	for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) {
+		if (cpu_freq >= ratio->cpu_freq) {
+			if (ratio->emc_freq >= tegra->max_freq)
+				return tegra->max_freq;
+			else
+				return ratio->emc_freq;
+		}
+	}
+
+	return 0;
+}
+
+static void actmon_update_target(struct tegra_devfreq *tegra,
+				 struct tegra_devfreq_device *dev)
+{
+	unsigned long cpu_freq = 0;
+	unsigned long static_cpu_emc_freq = 0;
+	unsigned int avg_sustain_coef;
+	unsigned long flags;
+
+	if (dev->config->avg_dependency_threshold) {
+		cpu_freq = cpufreq_get(0);
+		static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
+	}
+
+	spin_lock_irqsave(&tegra->lock, flags);
+
+	dev->target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
+	avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
+	dev->target_freq = do_percent(dev->target_freq, avg_sustain_coef);
+	dev->target_freq += dev->boost_freq;
+
+	if (dev->avg_count >= dev->config->avg_dependency_threshold)
+		dev->target_freq = max(dev->target_freq, static_cpu_emc_freq);
+
+	spin_unlock_irqrestore(&tegra->lock, flags);
+}
+
+static irqreturn_t actmon_thread_isr(int irq, void *data)
+{
+	struct tegra_devfreq *tegra = data;
+
+	mutex_lock(&tegra->devfreq->lock);
+	update_devfreq(tegra->devfreq);
+	mutex_unlock(&tegra->devfreq->lock);
+
+	return IRQ_HANDLED;
+}
+
+static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
+				       unsigned long action, void *ptr)
+{
+	struct clk_notifier_data *data = ptr;
+	struct tegra_devfreq *tegra = container_of(nb, struct tegra_devfreq,
+						   rate_change_nb);
+	unsigned int i;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tegra->lock, flags);
+
+	switch (action) {
+	case POST_RATE_CHANGE:
+		tegra->cur_freq = data->new_rate / KHZ;
+
+		for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
+			tegra_devfreq_update_wmark(tegra, tegra->devices + i);
+
+		actmon_write_barrier(tegra);
+		break;
+	case PRE_RATE_CHANGE:
+		/* fall through */
+	case ABORT_RATE_CHANGE:
+		break;
+	};
+
+	spin_unlock_irqrestore(&tegra->lock, flags);
+
+	return NOTIFY_OK;
+}
+
+static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
+					  struct tegra_devfreq_device *dev)
+{
+	u32 val;
+
+	dev->avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
+	dev->target_freq = tegra->cur_freq;
+
+	dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
+	writel(dev->avg_count, dev->regs + ACTMON_DEV_INIT_AVG);
+
+	tegra_devfreq_update_avg_wmark(dev);
+	tegra_devfreq_update_wmark(tegra, dev);
+
+	writel(ACTMON_COUNT_WEIGHT, dev->regs + ACTMON_DEV_COUNT_WEIGHT);
+	writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
+
+	val = 0;
+	val |= ACTMON_DEV_CTRL_ENB_PERIODIC |
+	       ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN |
+	       ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
+	val |= (ACTMON_AVERAGE_WINDOW_LOG2 - 1)
+		<< ACTMON_DEV_CTRL_K_VAL_SHIFT;
+	val |= (ACTMON_BELOW_WMARK_WINDOW - 1)
+		<< ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT;
+	val |= (ACTMON_ABOVE_WMARK_WINDOW - 1)
+		<< ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
+	val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN |
+	       ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
+
+	writel(val, dev->regs + ACTMON_DEV_CTRL);
+
+	actmon_write_barrier(tegra);
+
+	val = readl(dev->regs + ACTMON_DEV_CTRL);
+	val |= ACTMON_DEV_CTRL_ENB;
+	writel(val, dev->regs + ACTMON_DEV_CTRL);
+
+	actmon_write_barrier(tegra);
+}
+
+static int tegra_devfreq_suspend(struct device *dev)
+{
+	struct platform_device *pdev;
+	struct tegra_devfreq *tegra;
+	struct tegra_devfreq_device *actmon_dev;
+	unsigned int i;
+	u32 val;
+
+	pdev = container_of(dev, struct platform_device, dev);
+	tegra = platform_get_drvdata(pdev);
+
+	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
+		actmon_dev = &tegra->devices[i];
+
+		val = readl(actmon_dev->regs + ACTMON_DEV_CTRL);
+		val &= ~ACTMON_DEV_CTRL_ENB;
+		writel(val, actmon_dev->regs + ACTMON_DEV_CTRL);
+
+		writel(ACTMON_INTR_STATUS_CLEAR,
+		       actmon_dev->regs + ACTMON_DEV_INTR_STATUS);
+
+		actmon_write_barrier(tegra);
+	}
+
+	return 0;
+}
+
+static int tegra_devfreq_resume(struct device *dev)
+{
+	struct platform_device *pdev;
+	struct tegra_devfreq *tegra;
+	struct tegra_devfreq_device *actmon_dev;
+	unsigned int i;
+
+	pdev = container_of(dev, struct platform_device, dev);
+	tegra = platform_get_drvdata(pdev);
+
+	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
+		actmon_dev = &tegra->devices[i];
+
+		tegra_actmon_configure_device(tegra, actmon_dev);
+	}
+
+	return 0;
+}
+
+static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
+				u32 flags)
+{
+	struct platform_device *pdev;
+	struct tegra_devfreq *tegra;
+	struct dev_pm_opp *opp;
+	unsigned long rate = *freq * KHZ;
+
+	pdev = container_of(dev, struct platform_device, dev);
+	tegra = platform_get_drvdata(pdev);
+
+	rcu_read_lock();
+	opp = devfreq_recommended_opp(dev, &rate, flags);
+	if (IS_ERR(opp)) {
+		rcu_read_unlock();
+		dev_err(dev, "Failed to find opp for %lu KHz\n", *freq);
+		return PTR_ERR(opp);
+	}
+	rate = dev_pm_opp_get_freq(opp);
+	rcu_read_unlock();
+
+	/* TODO: Once we have per-user clk constraints, set a floor */
+	clk_set_rate(tegra->emc_clock, rate);
+
+	/* TODO: Set voltage as well */
+
+	return 0;
+}
+
+static int tegra_devfreq_get_dev_status(struct device *dev,
+					struct devfreq_dev_status *stat)
+{
+	struct platform_device *pdev;
+	struct tegra_devfreq *tegra;
+	struct tegra_devfreq_device *actmon_dev;
+
+	pdev = container_of(dev, struct platform_device, dev);
+	tegra = platform_get_drvdata(pdev);
+
+	stat->current_frequency = tegra->cur_freq;
+
+	/* To be used by the tegra governor */
+	stat->private_data = tegra;
+
+	/* The below are to be used by the other governors */
+
+	actmon_dev = &tegra->devices[MCALL];
+
+	/* Number of cycles spent on memory access */
+	stat->busy_time = actmon_dev->avg_count;
+
+	/* The bus can be considered to be saturated way before 100% */
+	stat->busy_time *= 100 / BUS_SATURATION_RATIO;
+
+	/* Number of cycles in a sampling period */
+	stat->total_time = ACTMON_SAMPLING_PERIOD * tegra->cur_freq;
+
+	return 0;
+}
+
+static int tegra_devfreq_get_target(struct devfreq *devfreq,
+				    unsigned long *freq)
+{
+	struct devfreq_dev_status stat;
+	struct tegra_devfreq *tegra;
+	struct tegra_devfreq_device *dev;
+	unsigned long target_freq = 0;
+	unsigned int i;
+	int err;
+
+	err = devfreq->profile->get_dev_status(devfreq->dev.parent, &stat);
+	if (err)
+		return err;
+
+	tegra = stat.private_data;
+
+	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
+		dev = &tegra->devices[i];
+
+		actmon_update_target(tegra, dev);
+
+		target_freq = max(target_freq, dev->target_freq);
+	}
+
+	*freq = target_freq;
+
+	return 0;
+}
+
+static int tegra_devfreq_event_handler(struct devfreq *devfreq,
+				       unsigned int event, void *data)
+{
+	return 0;
+}
+
+static struct devfreq_governor tegra_devfreq_governor = {
+	.name = "tegra",
+	.get_target_freq = tegra_devfreq_get_target,
+	.event_handler = tegra_devfreq_event_handler,
+};
+
+static struct devfreq_dev_profile tegra_devfreq_profile = {
+	.polling_ms	= 0,
+	.target		= tegra_devfreq_target,
+	.get_dev_status	= tegra_devfreq_get_dev_status,
+};
+
+static int tegra_devfreq_probe(struct platform_device *pdev)
+{
+	struct tegra_devfreq *tegra;
+	struct tegra_devfreq_device *dev;
+	struct resource *res;
+	unsigned long max_freq;
+	unsigned int i;
+	int irq;
+	int err;
+
+	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
+	if (!tegra)
+		return -ENOMEM;
+
+	spin_lock_init(&tegra->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Failed to get regs resource\n");
+		return -ENODEV;
+	}
+
+	tegra->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(tegra->regs)) {
+		dev_err(&pdev->dev, "Failed to get IO memory\n");
+		return PTR_ERR(tegra->regs);
+	}
+
+	tegra->reset = devm_reset_control_get(&pdev->dev, "actmon");
+	if (IS_ERR(tegra->reset)) {
+		dev_err(&pdev->dev, "Failed to get reset\n");
+		return PTR_ERR(tegra->reset);
+	}
+
+	tegra->clock = devm_clk_get(&pdev->dev, "actmon");
+	if (IS_ERR(tegra->clock)) {
+		dev_err(&pdev->dev, "Failed to get actmon clock\n");
+		return PTR_ERR(tegra->clock);
+	}
+
+	tegra->emc_clock = devm_clk_get(&pdev->dev, "emc");
+	if (IS_ERR(tegra->emc_clock)) {
+		dev_err(&pdev->dev, "Failed to get emc clock\n");
+		return PTR_ERR(tegra->emc_clock);
+	}
+
+	err = of_init_opp_table(&pdev->dev);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to init operating point table\n");
+		return err;
+	}
+
+	tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
+	err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
+	if (err) {
+		dev_err(&pdev->dev,
+			"Failed to register rate change notifier\n");
+		return err;
+	}
+
+	reset_control_assert(tegra->reset);
+
+	err = clk_prepare_enable(tegra->clock);
+	if (err) {
+		reset_control_deassert(tegra->reset);
+		return err;
+	}
+
+	reset_control_deassert(tegra->reset);
+
+	max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX);
+	tegra->max_freq = max_freq / KHZ;
+
+	clk_set_rate(tegra->emc_clock, max_freq);
+
+	tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
+
+	writel(ACTMON_SAMPLING_PERIOD - 1,
+	       tegra->regs + ACTMON_GLB_PERIOD_CTRL);
+
+	for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
+		dev = tegra->devices + i;
+		dev->config = actmon_device_configs + i;
+		dev->regs = tegra->regs + dev->config->offset;
+
+		tegra_actmon_configure_device(tegra, tegra->devices + i);
+	}
+
+	err = devfreq_add_governor(&tegra_devfreq_governor);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to add governor\n");
+		return err;
+	}
+
+	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
+	tegra->devfreq = devm_devfreq_add_device(&pdev->dev,
+						 &tegra_devfreq_profile,
+						 "tegra",
+						 NULL);
+
+	irq = platform_get_irq(pdev, 0);
+	err = devm_request_threaded_irq(&pdev->dev, irq, actmon_isr,
+					actmon_thread_isr, IRQF_SHARED,
+					"tegra-devfreq", tegra);
+	if (err) {
+		dev_err(&pdev->dev, "Interrupt request failed\n");
+		return err;
+	}
+
+	platform_set_drvdata(pdev, tegra);
+
+	return 0;
+}
+
+static int tegra_devfreq_remove(struct platform_device *pdev)
+{
+	struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
+
+	clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
+
+	clk_disable_unprepare(tegra->clock);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(tegra_devfreq_pm_ops,
+			 tegra_devfreq_suspend,
+			 tegra_devfreq_resume);
+
+static struct of_device_id tegra_devfreq_of_match[] = {
+	{ .compatible = "nvidia,tegra124-actmon" },
+	{ },
+};
+
+static struct platform_driver tegra_devfreq_driver = {
+	.probe	= tegra_devfreq_probe,
+	.remove	= tegra_devfreq_remove,
+	.driver = {
+		.name		= "tegra-devfreq",
+		.owner		= THIS_MODULE,
+		.of_match_table = tegra_devfreq_of_match,
+		.pm		= &tegra_devfreq_pm_ops,
+	},
+};
+module_platform_driver(tegra_devfreq_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Tegra devfreq driver");
+MODULE_AUTHOR("Tomeu Vizoso <tomeu.vizoso@collabora.com>");
+MODULE_DEVICE_TABLE(of, tegra_devfreq_of_match);
-- 
1.9.3

Re: [PATCH v2 2/3] PM / devfreq: tegra: add devfreq driver for Tegra Activity Monitor

[Alexandre Courbot]

On Mon, Nov 24, 2014 at 9:28 PM, Tomeu Vizoso
<tomeu.vizoso@collabora.com> wrote:
> The ACTMON block can monitor several counters, providing averaging and firing
> interrupts based on watermarking configuration. This implementation monitors
> the MCALL and MCCPU counters to choose an appropriate frequency for the
> external memory clock.
>
> This patch is based on work by Alex Frid <afrid@nvidia.com> and Mikko
> Perttunen <mikko.perttunen@kapsi.fi>.

Thanks for taking the time to adapt this driver to use devfreq.
Looking at it, I am more and more convinced that's the correct way to
do.

I made some comments inline, but I'd like to bring Arto Merilainen
into this discussion. Arto thought (and might even have some code)
about adding watermarks support to devfreq's core and using a generic
"watermark" governor which I believe would greatly benefit this patch
set. Arto, do you have some concrete code you could submit here? If
you lack the time for doing so, some guidance so we could implement
this support ourselves would be great.

>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>
> ---
>
> v2:     * Use devfreq
> ---
>  drivers/devfreq/Kconfig         |  10 +
>  drivers/devfreq/Makefile        |   1 +
>  drivers/devfreq/tegra-devfreq.c | 718 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 729 insertions(+)
>  create mode 100644 drivers/devfreq/tegra-devfreq.c
>
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index faf4e70..4aab799 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -87,4 +87,14 @@ config ARM_EXYNOS5_BUS_DEVFREQ
>           It reads PPMU counters of memory controllers and adjusts the
>           operating frequencies and voltages with OPP support.
>
> +config ARM_TEGRA_DEVFREQ
> +       tristate "Tegra DEVFREQ Driver"
> +       depends on ARCH_TEGRA_124_SOC
> +       select DEVFREQ_GOV_SIMPLE_ONDEMAND
> +       select PM_OPP
> +       help
> +         This adds the DEVFREQ driver for the Tegra family of SoCs.
> +         It reads ACTMON counters of memory controllers and adjusts the
> +         operating frequencies and voltages with OPP support.
> +
>  endif # PM_DEVFREQ
> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> index 16138c9..0ea991f 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)     += governor_userspace.o
>  # DEVFREQ Drivers
>  obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)  += exynos/
>  obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)  += exynos/
> +obj-$(CONFIG_ARM_TEGRA_DEVFREQ)                += tegra-devfreq.o
> diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
> new file mode 100644
> index 0000000..3479096
> --- /dev/null
> +++ b/drivers/devfreq/tegra-devfreq.c

This file should probably be named tegra-actmon-devfreq.c, for nothing
guarantees that we will not have more devfreq devices for Tegra in the
future.

> @@ -0,0 +1,718 @@
> +/*
> + * A devfreq driver for NVIDIA Tegra SoCs
> + *
> + * Copyright (c) 2014 NVIDIA CORPORATION. All rights reserved.
> + * Copyright (C) 2014 Google, Inc
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/cpufreq.h>
> +#include <linux/devfreq.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> +#include <linux/reset.h>
> +
> +#include "governor.h"
> +
> +#define ACTMON_GLB_STATUS                                      0x0
> +#define ACTMON_GLB_PERIOD_CTRL                                 0x4
> +
> +#define ACTMON_DEV_CTRL                                                0x0
> +#define ACTMON_DEV_CTRL_K_VAL_SHIFT                            10
> +#define ACTMON_DEV_CTRL_ENB_PERIODIC                           BIT(18)
> +#define ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN                     BIT(20)
> +#define ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN                     BIT(21)
> +#define ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT      23
> +#define ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT      26
> +#define ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN             BIT(29)
> +#define ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN             BIT(30)
> +#define ACTMON_DEV_CTRL_ENB                                    BIT(31)
> +
> +#define ACTMON_DEV_UPPER_WMARK                                 0x4
> +#define ACTMON_DEV_LOWER_WMARK                                 0x8
> +#define ACTMON_DEV_INIT_AVG                                    0xc
> +#define ACTMON_DEV_AVG_UPPER_WMARK                             0x10
> +#define ACTMON_DEV_AVG_LOWER_WMARK                             0x14
> +#define ACTMON_DEV_COUNT_WEIGHT                                        0x18
> +#define ACTMON_DEV_AVG_COUNT                                   0x20
> +#define ACTMON_DEV_INTR_STATUS                                 0x24
> +
> +#define ACTMON_INTR_STATUS_CLEAR                               0xffffffff
> +
> +#define ACTMON_DEV_INTR_CONSECUTIVE_UPPER                      BIT(31)
> +#define ACTMON_DEV_INTR_CONSECUTIVE_LOWER                      BIT(30)
> +
> +#define ACTMON_ABOVE_WMARK_WINDOW                              1
> +#define ACTMON_BELOW_WMARK_WINDOW                              3
> +#define ACTMON_BOOST_FREQ_STEP                                 16000
> +
> +/* activity counter is incremented every 256 memory transactions, and each
> + * transaction takes 4 EMC clocks for Tegra124; So the COUNT_WEIGHT is
> + * 4 * 256 = 1024.
> + */
> +#define ACTMON_COUNT_WEIGHT                                    0x400
> +
> +/*
> + * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which
> + * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128
> + */
> +#define ACTMON_AVERAGE_WINDOW_LOG2                     6
> +#define ACTMON_SAMPLING_PERIOD                         12 /* ms */
> +#define ACTMON_DEFAULT_AVG_BAND                                6  /* 1/10 of % */
> +
> +#define KHZ                                                    1000
> +
> +/* Assume that the bus is saturated if the utilization is 25% */
> +#define BUS_SATURATION_RATIO                                   25
> +
> +/**
> + * struct tegra_devfreq_device_config - configuration specific to an ACTMON
> + * device
> + *
> + * Coefficients and thresholds are in %

Short comments about what the members are for would be perfect (same
for other structures). It is not immediatly obvious what e.g.
avg_dependency_threshold is for.

> + */
> +struct tegra_devfreq_device_config {
> +       u32             offset;
> +       u32             irq_mask;
> +
> +       unsigned int    boost_up_coeff;
> +       unsigned int    boost_down_coeff;
> +       unsigned int    boost_up_threshold;
> +       unsigned int    boost_down_threshold;
> +       u32             avg_dependency_threshold;
> +};
> +
> +enum tegra_actmon_device {
> +       MCALL = 0,
> +       MCCPU,
> +};
> +
> +static struct tegra_devfreq_device_config actmon_device_configs[] = {
> +       {
> +               /* MCALL */
> +               .offset = 0x1c0,
> +               .irq_mask = 1 << 26,
> +               .boost_up_coeff = 200,
> +               .boost_down_coeff = 50,
> +               .boost_up_threshold = 60,
> +               .boost_down_threshold = 40,
> +       },
> +       {
> +               /* MCCPU */
> +               .offset = 0x200,
> +               .irq_mask = 1 << 25,
> +               .boost_up_coeff = 800,
> +               .boost_down_coeff = 90,
> +               .boost_up_threshold = 27,
> +               .boost_down_threshold = 10,
> +               .avg_dependency_threshold = 50000,

The boost_* and avg_dependency_threshold parameters are calling to be
exported through debugfs in some future patch. :)

Just for my education, why do we need to monitor both MCALL and MCCPU,
since MCCPU accesses are included in MCALL? Do we want to boost things
differently in case of CPU activity?

> +       },
> +};
> +
> +/**
> + * struct tegra_devfreq_device - state specific to an ACTMON device
> + *
> + * Frequencies are in kHz.
> + */
> +struct tegra_devfreq_device {
> +       const struct tegra_devfreq_device_config *config;
> +
> +       void __iomem    *regs;
> +       u32             avg_band_freq;
> +       u32             avg_count;
> +
> +       unsigned long   target_freq;
> +       unsigned long   boost_freq;
> +};
> +
> +struct tegra_devfreq {
> +       struct devfreq          *devfreq;
> +
> +       struct platform_device  *pdev;
> +       struct reset_control    *reset;
> +       struct clk              *clock;
> +       void __iomem            *regs;
> +
> +       spinlock_t              lock;
> +
> +       struct clk              *emc_clock;
> +       unsigned long           max_freq;
> +       unsigned long           cur_freq;
> +       struct notifier_block   rate_change_nb;
> +
> +       struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
> +};
> +
> +struct tegra_actmon_emc_ratio {
> +       unsigned long cpu_freq;
> +       unsigned long emc_freq;
> +};
> +
> +static struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
> +       { 1400000, ULONG_MAX },
> +       { 1200000,    750000 },
> +       { 1100000,    600000 },
> +       { 1000000,    500000 },
> +       {  800000,    375000 },
> +       {  500000,    200000 },
> +       {  250000,    100000 },

Aren't these numbers board-specific? Should they be moved to the DT maybe?

> +};
> +
> +static unsigned long do_percent(unsigned long val, unsigned int pct)
> +{
> +       return val * pct / 100;
> +}
> +
> +static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq_device *dev)
> +{
> +       u32 avg = dev->avg_count;
> +       u32 band = dev->avg_band_freq * ACTMON_SAMPLING_PERIOD;
> +
> +       writel(avg + band, dev->regs + ACTMON_DEV_AVG_UPPER_WMARK);

Having actmon_readl() and actmon_writel() inline functions that make
the "dev->regs +" unnecessary would be nicer to read and less
error-prone IMHO.

> +       avg = max(avg, band);
> +       writel(avg - band, dev->regs + ACTMON_DEV_AVG_LOWER_WMARK);
> +}
> +
> +static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
> +                                      struct tegra_devfreq_device *dev)
> +{
> +       u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
> +
> +       writel(do_percent(val, dev->config->boost_up_threshold),
> +              dev->regs + ACTMON_DEV_UPPER_WMARK);
> +
> +       writel(do_percent(val, dev->config->boost_down_threshold),
> +              dev->regs + ACTMON_DEV_LOWER_WMARK);
> +}
> +
> +static void actmon_write_barrier(struct tegra_devfreq *tegra)
> +{
> +       /* ensure the update has reached the ACTMON */
> +       wmb();
> +       readl(tegra->regs + ACTMON_GLB_STATUS);
> +}
> +
> +static irqreturn_t actmon_isr(int irq, void *data)
> +{
> +       struct tegra_devfreq *tegra = data;
> +       struct tegra_devfreq_device *dev = NULL;
> +       unsigned long flags;
> +       u32 val;
> +       unsigned int i;
> +
> +       val = readl(tegra->regs + ACTMON_GLB_STATUS);
> +
> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> +               if (val & tegra->devices[i].config->irq_mask) {
> +                       dev = tegra->devices + i;
> +                       break;
> +               }
> +       }
> +
> +       if (!dev)
> +               return IRQ_NONE;
> +
> +       spin_lock_irqsave(&tegra->lock, flags);
> +
> +       dev->avg_count = readl(dev->regs + ACTMON_DEV_AVG_COUNT);
> +       tegra_devfreq_update_avg_wmark(dev);
> +
> +       val = readl(dev->regs + ACTMON_DEV_INTR_STATUS);
> +       if (val & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) {
> +               val = readl(dev->regs + ACTMON_DEV_CTRL) |
> +                       ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN |
> +                       ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
> +
> +               /*
> +                * new_boost = min(old_boost * up_coef + step, max_freq)
> +                */
> +               dev->boost_freq = do_percent(dev->boost_freq,
> +                                            dev->config->boost_up_coeff);
> +               dev->boost_freq += ACTMON_BOOST_FREQ_STEP;
> +               if (dev->boost_freq >= tegra->max_freq) {
> +                       dev->boost_freq = tegra->max_freq;
> +                       val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;

Instead of setting this flag to possibly remove it later, maybe set it
only if this condition is not met?

> +               }
> +               writel(val, dev->regs + ACTMON_DEV_CTRL);
> +       } else if (val & ACTMON_DEV_INTR_CONSECUTIVE_LOWER) {
> +               val = readl(dev->regs + ACTMON_DEV_CTRL) |
> +                       ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN |
> +                       ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
> +
> +               /*
> +                * new_boost = old_boost * down_coef
> +                * or 0 if (old_boost * down_coef < step / 2)
> +                */
> +               dev->boost_freq = do_percent(dev->boost_freq,
> +                                            dev->config->boost_down_coeff);
> +               if (dev->boost_freq < (ACTMON_BOOST_FREQ_STEP >> 1)) {
> +                       dev->boost_freq = 0;
> +                       val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;

Same here.

> +               }
> +               writel(val, dev->regs + ACTMON_DEV_CTRL);
> +       }
> +
> +       if (dev->config->avg_dependency_threshold) {
> +               val = readl(dev->regs + ACTMON_DEV_CTRL);
> +               if (dev->avg_count >= dev->config->avg_dependency_threshold)
> +                       val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
> +               else if (dev->boost_freq == 0)
> +                       val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
> +               writel(val, dev->regs + ACTMON_DEV_CTRL);
> +       }
> +
> +       writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
> +
> +       actmon_write_barrier(tegra);
> +
> +       spin_unlock_irqrestore(&tegra->lock, flags);
> +
> +       return IRQ_WAKE_THREAD;
> +}
> +
> +static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
> +                                           unsigned long cpu_freq)
> +{
> +       unsigned int i;
> +       struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
> +
> +       for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) {
> +               if (cpu_freq >= ratio->cpu_freq) {
> +                       if (ratio->emc_freq >= tegra->max_freq)
> +                               return tegra->max_freq;
> +                       else
> +                               return ratio->emc_freq;
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +static void actmon_update_target(struct tegra_devfreq *tegra,
> +                                struct tegra_devfreq_device *dev)
> +{
> +       unsigned long cpu_freq = 0;
> +       unsigned long static_cpu_emc_freq = 0;
> +       unsigned int avg_sustain_coef;
> +       unsigned long flags;
> +
> +       if (dev->config->avg_dependency_threshold) {
> +               cpu_freq = cpufreq_get(0);
> +               static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
> +       }
> +
> +       spin_lock_irqsave(&tegra->lock, flags);
> +
> +       dev->target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
> +       avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
> +       dev->target_freq = do_percent(dev->target_freq, avg_sustain_coef);
> +       dev->target_freq += dev->boost_freq;
> +
> +       if (dev->avg_count >= dev->config->avg_dependency_threshold)
> +               dev->target_freq = max(dev->target_freq, static_cpu_emc_freq);
> +
> +       spin_unlock_irqrestore(&tegra->lock, flags);
> +}
> +
> +static irqreturn_t actmon_thread_isr(int irq, void *data)
> +{
> +       struct tegra_devfreq *tegra = data;
> +
> +       mutex_lock(&tegra->devfreq->lock);
> +       update_devfreq(tegra->devfreq);
> +       mutex_unlock(&tegra->devfreq->lock);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
> +                                      unsigned long action, void *ptr)
> +{
> +       struct clk_notifier_data *data = ptr;
> +       struct tegra_devfreq *tegra = container_of(nb, struct tegra_devfreq,
> +                                                  rate_change_nb);
> +       unsigned int i;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&tegra->lock, flags);
> +
> +       switch (action) {
> +       case POST_RATE_CHANGE:
> +               tegra->cur_freq = data->new_rate / KHZ;
> +
> +               for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
> +                       tegra_devfreq_update_wmark(tegra, tegra->devices + i);
> +
> +               actmon_write_barrier(tegra);
> +               break;
> +       case PRE_RATE_CHANGE:
> +               /* fall through */
> +       case ABORT_RATE_CHANGE:

Can't you use "default:" here instead?

> +               break;
> +       };
> +
> +       spin_unlock_irqrestore(&tegra->lock, flags);
> +
> +       return NOTIFY_OK;
> +}
> +
> +static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
> +                                         struct tegra_devfreq_device *dev)
> +{
> +       u32 val;
> +
> +       dev->avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
> +       dev->target_freq = tegra->cur_freq;
> +
> +       dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
> +       writel(dev->avg_count, dev->regs + ACTMON_DEV_INIT_AVG);
> +
> +       tegra_devfreq_update_avg_wmark(dev);
> +       tegra_devfreq_update_wmark(tegra, dev);
> +
> +       writel(ACTMON_COUNT_WEIGHT, dev->regs + ACTMON_DEV_COUNT_WEIGHT);
> +       writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
> +
> +       val = 0;
> +       val |= ACTMON_DEV_CTRL_ENB_PERIODIC |
> +              ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN |
> +              ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
> +       val |= (ACTMON_AVERAGE_WINDOW_LOG2 - 1)
> +               << ACTMON_DEV_CTRL_K_VAL_SHIFT;
> +       val |= (ACTMON_BELOW_WMARK_WINDOW - 1)
> +               << ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT;
> +       val |= (ACTMON_ABOVE_WMARK_WINDOW - 1)
> +               << ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
> +       val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN |
> +              ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
> +
> +       writel(val, dev->regs + ACTMON_DEV_CTRL);
> +
> +       actmon_write_barrier(tegra);
> +
> +       val = readl(dev->regs + ACTMON_DEV_CTRL);
> +       val |= ACTMON_DEV_CTRL_ENB;
> +       writel(val, dev->regs + ACTMON_DEV_CTRL);
> +
> +       actmon_write_barrier(tegra);
> +}
> +
> +static int tegra_devfreq_suspend(struct device *dev)
> +{
> +       struct platform_device *pdev;
> +       struct tegra_devfreq *tegra;
> +       struct tegra_devfreq_device *actmon_dev;
> +       unsigned int i;
> +       u32 val;
> +
> +       pdev = container_of(dev, struct platform_device, dev);
> +       tegra = platform_get_drvdata(pdev);
> +
> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> +               actmon_dev = &tegra->devices[i];
> +
> +               val = readl(actmon_dev->regs + ACTMON_DEV_CTRL);
> +               val &= ~ACTMON_DEV_CTRL_ENB;
> +               writel(val, actmon_dev->regs + ACTMON_DEV_CTRL);
> +
> +               writel(ACTMON_INTR_STATUS_CLEAR,
> +                      actmon_dev->regs + ACTMON_DEV_INTR_STATUS);
> +
> +               actmon_write_barrier(tegra);
> +       }
> +
> +       return 0;
> +}
> +
> +static int tegra_devfreq_resume(struct device *dev)
> +{
> +       struct platform_device *pdev;
> +       struct tegra_devfreq *tegra;
> +       struct tegra_devfreq_device *actmon_dev;
> +       unsigned int i;
> +
> +       pdev = container_of(dev, struct platform_device, dev);
> +       tegra = platform_get_drvdata(pdev);
> +
> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> +               actmon_dev = &tegra->devices[i];
> +
> +               tegra_actmon_configure_device(tegra, actmon_dev);
> +       }
> +
> +       return 0;
> +}
> +
> +static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
> +                               u32 flags)
> +{
> +       struct platform_device *pdev;
> +       struct tegra_devfreq *tegra;
> +       struct dev_pm_opp *opp;
> +       unsigned long rate = *freq * KHZ;
> +
> +       pdev = container_of(dev, struct platform_device, dev);
> +       tegra = platform_get_drvdata(pdev);
> +
> +       rcu_read_lock();
> +       opp = devfreq_recommended_opp(dev, &rate, flags);
> +       if (IS_ERR(opp)) {
> +               rcu_read_unlock();
> +               dev_err(dev, "Failed to find opp for %lu KHz\n", *freq);
> +               return PTR_ERR(opp);
> +       }
> +       rate = dev_pm_opp_get_freq(opp);
> +       rcu_read_unlock();
> +
> +       /* TODO: Once we have per-user clk constraints, set a floor */
> +       clk_set_rate(tegra->emc_clock, rate);
> +
> +       /* TODO: Set voltage as well */
> +
> +       return 0;
> +}
> +
> +static int tegra_devfreq_get_dev_status(struct device *dev,
> +                                       struct devfreq_dev_status *stat)
> +{
> +       struct platform_device *pdev;
> +       struct tegra_devfreq *tegra;
> +       struct tegra_devfreq_device *actmon_dev;
> +
> +       pdev = container_of(dev, struct platform_device, dev);
> +       tegra = platform_get_drvdata(pdev);
> +
> +       stat->current_frequency = tegra->cur_freq;
> +
> +       /* To be used by the tegra governor */
> +       stat->private_data = tegra;
> +
> +       /* The below are to be used by the other governors */
> +
> +       actmon_dev = &tegra->devices[MCALL];
> +
> +       /* Number of cycles spent on memory access */
> +       stat->busy_time = actmon_dev->avg_count;
> +
> +       /* The bus can be considered to be saturated way before 100% */
> +       stat->busy_time *= 100 / BUS_SATURATION_RATIO;
> +
> +       /* Number of cycles in a sampling period */
> +       stat->total_time = ACTMON_SAMPLING_PERIOD * tegra->cur_freq;
> +
> +       return 0;
> +}
> +
> +static int tegra_devfreq_get_target(struct devfreq *devfreq,
> +                                   unsigned long *freq)
> +{
> +       struct devfreq_dev_status stat;
> +       struct tegra_devfreq *tegra;
> +       struct tegra_devfreq_device *dev;
> +       unsigned long target_freq = 0;
> +       unsigned int i;
> +       int err;
> +
> +       err = devfreq->profile->get_dev_status(devfreq->dev.parent, &stat);
> +       if (err)
> +               return err;
> +
> +       tegra = stat.private_data;
> +
> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> +               dev = &tegra->devices[i];
> +
> +               actmon_update_target(tegra, dev);
> +
> +               target_freq = max(target_freq, dev->target_freq);
> +       }

I *think* you should be able to remove the dependency on
tegra_devfreq_device from this function (ideally, governors should be
device-agnostic). Since you call get_dev_status() from this function
anyway, why not moving the actmon_update_target() calls into
tegra_devfreq_get_dev_status(), and write busy_time/total_time values
that will make tegra_devfreq_get_target() infer the right frequency?

> +
> +       *freq = target_freq;
> +
> +       return 0;
> +}
> +
> +static int tegra_devfreq_event_handler(struct devfreq *devfreq,
> +                                      unsigned int event, void *data)
> +{
> +       return 0;
> +}

I think you will need an implementation of this. Upon
DEVFREQ_GOV_START/DEVFREQ_GOV_RESUME, enable actmon interrupts. On
DEVFREQ_GOV_STOP/DEVFREQ_GOV_SUSPEND, disable interrupts. I know you
are doing it somewhere, but it should be done here as this is what
devfreq expects (e.g. to correctly stop interrupts if you switch from
the "tegra" to the "performance" governor).

Sadly, this adds the exact same dependency on tegra_devfreq that I
tried to remove from the previous function, which is unfortunate. This
is where watermarking support in devfreq would be useful - when
starting the governor, we could ask the device to monitor some low and
high marks through new hooks and handle all this nicely.

> +
> +static struct devfreq_governor tegra_devfreq_governor = {
> +       .name = "tegra",

This governor could certainly get a more specific name. :P

> +       .get_target_freq = tegra_devfreq_get_target,
> +       .event_handler = tegra_devfreq_event_handler,
> +};
> +
> +static struct devfreq_dev_profile tegra_devfreq_profile = {
> +       .polling_ms     = 0,
> +       .target         = tegra_devfreq_target,
> +       .get_dev_status = tegra_devfreq_get_dev_status,
> +};

Maybe move this declaration right after the declaration of
tegra_devfreq_get_dev_status() to make things easier to put together
in the reader's mind.

> +
> +static int tegra_devfreq_probe(struct platform_device *pdev)
> +{
> +       struct tegra_devfreq *tegra;
> +       struct tegra_devfreq_device *dev;
> +       struct resource *res;
> +       unsigned long max_freq;
> +       unsigned int i;
> +       int irq;
> +       int err;
> +
> +       tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
> +       if (!tegra)
> +               return -ENOMEM;
> +
> +       spin_lock_init(&tegra->lock);
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res) {
> +               dev_err(&pdev->dev, "Failed to get regs resource\n");
> +               return -ENODEV;
> +       }
> +
> +       tegra->regs = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(tegra->regs)) {
> +               dev_err(&pdev->dev, "Failed to get IO memory\n");
> +               return PTR_ERR(tegra->regs);
> +       }
> +
> +       tegra->reset = devm_reset_control_get(&pdev->dev, "actmon");
> +       if (IS_ERR(tegra->reset)) {
> +               dev_err(&pdev->dev, "Failed to get reset\n");
> +               return PTR_ERR(tegra->reset);
> +       }
> +
> +       tegra->clock = devm_clk_get(&pdev->dev, "actmon");
> +       if (IS_ERR(tegra->clock)) {
> +               dev_err(&pdev->dev, "Failed to get actmon clock\n");
> +               return PTR_ERR(tegra->clock);
> +       }
> +
> +       tegra->emc_clock = devm_clk_get(&pdev->dev, "emc");
> +       if (IS_ERR(tegra->emc_clock)) {
> +               dev_err(&pdev->dev, "Failed to get emc clock\n");
> +               return PTR_ERR(tegra->emc_clock);
> +       }
> +
> +       err = of_init_opp_table(&pdev->dev);
> +       if (err) {
> +               dev_err(&pdev->dev, "Failed to init operating point table\n");
> +               return err;
> +       }
> +
> +       tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
> +       err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
> +       if (err) {
> +               dev_err(&pdev->dev,
> +                       "Failed to register rate change notifier\n");
> +               return err;
> +       }
> +
> +       reset_control_assert(tegra->reset);
> +
> +       err = clk_prepare_enable(tegra->clock);
> +       if (err) {
> +               reset_control_deassert(tegra->reset);
> +               return err;
> +       }
> +
> +       reset_control_deassert(tegra->reset);
> +
> +       max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX);
> +       tegra->max_freq = max_freq / KHZ;
> +
> +       clk_set_rate(tegra->emc_clock, max_freq);
> +
> +       tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
> +
> +       writel(ACTMON_SAMPLING_PERIOD - 1,
> +              tegra->regs + ACTMON_GLB_PERIOD_CTRL);
> +
> +       for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
> +               dev = tegra->devices + i;
> +               dev->config = actmon_device_configs + i;
> +               dev->regs = tegra->regs + dev->config->offset;
> +
> +               tegra_actmon_configure_device(tegra, tegra->devices + i);
> +       }
> +
> +       err = devfreq_add_governor(&tegra_devfreq_governor);

This should probably be done in an initcall (that would be executed
before probe() is called). We can in theory have several instances of
ACTMON, but the governor should only be added once in all cases. I
understand that this is unlikely to happen in practice though.

> +       if (err) {
> +               dev_err(&pdev->dev, "Failed to add governor\n");
> +               return err;
> +       }
> +
> +       tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
> +       tegra->devfreq = devm_devfreq_add_device(&pdev->dev,
> +                                                &tegra_devfreq_profile,
> +                                                "tegra",

I think "tegra_actmon" would look better here. :)

> +                                                NULL);
> +
> +       irq = platform_get_irq(pdev, 0);
> +       err = devm_request_threaded_irq(&pdev->dev, irq, actmon_isr,
> +                                       actmon_thread_isr, IRQF_SHARED,
> +                                       "tegra-devfreq", tegra);

You probably ought to do this *before* adding the devfreq device,
otherwise you are at risk of receiving interrupts nobody will handle.

> +       if (err) {
> +               dev_err(&pdev->dev, "Interrupt request failed\n");
> +               return err;
> +       }
> +
> +       platform_set_drvdata(pdev, tegra);

This should also be done before the call to devfreq_add_device().

> +
> +       return 0;
> +}
> +
> +static int tegra_devfreq_remove(struct platform_device *pdev)
> +{
> +       struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
> +
> +       clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
> +
> +       clk_disable_unprepare(tegra->clock);

There seems to be a lot missing in this function, like removing the
devfreq device?

Re: [PATCH v2 2/3] PM / devfreq: tegra: add devfreq driver for Tegra Activity Monitor

[Tomeu Vizoso]

On 26 November 2014 at 11:02, Alexandre Courbot <gnurou@gmail.com> wrote:
> On Mon, Nov 24, 2014 at 9:28 PM, Tomeu Vizoso
> <tomeu.vizoso@collabora.com> wrote:
>> The ACTMON block can monitor several counters, providing averaging and firing
>> interrupts based on watermarking configuration. This implementation monitors
>> the MCALL and MCCPU counters to choose an appropriate frequency for the
>> external memory clock.
>>
>> This patch is based on work by Alex Frid <afrid@nvidia.com> and Mikko
>> Perttunen <mikko.perttunen@kapsi.fi>.
>
> Thanks for taking the time to adapt this driver to use devfreq.
> Looking at it, I am more and more convinced that's the correct way to
> do.
>
> I made some comments inline, but I'd like to bring Arto Merilainen
> into this discussion. Arto thought (and might even have some code)
> about adding watermarks support to devfreq's core and using a generic
> "watermark" governor which I believe would greatly benefit this patch
> set.

Do you know of any other SoC family that would be able to use that code?

> Arto, do you have some concrete code you could submit here? If
> you lack the time for doing so, some guidance so we could implement
> this support ourselves would be great.
>
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>>
>> ---
>>
>> v2:     * Use devfreq
>> ---
>>  drivers/devfreq/Kconfig         |  10 +
>>  drivers/devfreq/Makefile        |   1 +
>>  drivers/devfreq/tegra-devfreq.c | 718 ++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 729 insertions(+)
>>  create mode 100644 drivers/devfreq/tegra-devfreq.c
>>
>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
>> index faf4e70..4aab799 100644
>> --- a/drivers/devfreq/Kconfig
>> +++ b/drivers/devfreq/Kconfig
>> @@ -87,4 +87,14 @@ config ARM_EXYNOS5_BUS_DEVFREQ
>>           It reads PPMU counters of memory controllers and adjusts the
>>           operating frequencies and voltages with OPP support.
>>
>> +config ARM_TEGRA_DEVFREQ
>> +       tristate "Tegra DEVFREQ Driver"
>> +       depends on ARCH_TEGRA_124_SOC
>> +       select DEVFREQ_GOV_SIMPLE_ONDEMAND
>> +       select PM_OPP
>> +       help
>> +         This adds the DEVFREQ driver for the Tegra family of SoCs.
>> +         It reads ACTMON counters of memory controllers and adjusts the
>> +         operating frequencies and voltages with OPP support.
>> +
>>  endif # PM_DEVFREQ
>> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
>> index 16138c9..0ea991f 100644
>> --- a/drivers/devfreq/Makefile
>> +++ b/drivers/devfreq/Makefile
>> @@ -7,3 +7,4 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)     += governor_userspace.o
>>  # DEVFREQ Drivers
>>  obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)  += exynos/
>>  obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)  += exynos/
>> +obj-$(CONFIG_ARM_TEGRA_DEVFREQ)                += tegra-devfreq.o
>> diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
>> new file mode 100644
>> index 0000000..3479096
>> --- /dev/null
>> +++ b/drivers/devfreq/tegra-devfreq.c
>
> This file should probably be named tegra-actmon-devfreq.c, for nothing
> guarantees that we will not have more devfreq devices for Tegra in the
> future.

Good point.

>> @@ -0,0 +1,718 @@
>> +/*
>> + * A devfreq driver for NVIDIA Tegra SoCs
>> + *
>> + * Copyright (c) 2014 NVIDIA CORPORATION. All rights reserved.
>> + * Copyright (C) 2014 Google, Inc
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
>> + *
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/cpufreq.h>
>> +#include <linux/devfreq.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_opp.h>
>> +#include <linux/reset.h>
>> +
>> +#include "governor.h"
>> +
>> +#define ACTMON_GLB_STATUS                                      0x0
>> +#define ACTMON_GLB_PERIOD_CTRL                                 0x4
>> +
>> +#define ACTMON_DEV_CTRL                                                0x0
>> +#define ACTMON_DEV_CTRL_K_VAL_SHIFT                            10
>> +#define ACTMON_DEV_CTRL_ENB_PERIODIC                           BIT(18)
>> +#define ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN                     BIT(20)
>> +#define ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN                     BIT(21)
>> +#define ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT      23
>> +#define ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT      26
>> +#define ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN             BIT(29)
>> +#define ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN             BIT(30)
>> +#define ACTMON_DEV_CTRL_ENB                                    BIT(31)
>> +
>> +#define ACTMON_DEV_UPPER_WMARK                                 0x4
>> +#define ACTMON_DEV_LOWER_WMARK                                 0x8
>> +#define ACTMON_DEV_INIT_AVG                                    0xc
>> +#define ACTMON_DEV_AVG_UPPER_WMARK                             0x10
>> +#define ACTMON_DEV_AVG_LOWER_WMARK                             0x14
>> +#define ACTMON_DEV_COUNT_WEIGHT                                        0x18
>> +#define ACTMON_DEV_AVG_COUNT                                   0x20
>> +#define ACTMON_DEV_INTR_STATUS                                 0x24
>> +
>> +#define ACTMON_INTR_STATUS_CLEAR                               0xffffffff
>> +
>> +#define ACTMON_DEV_INTR_CONSECUTIVE_UPPER                      BIT(31)
>> +#define ACTMON_DEV_INTR_CONSECUTIVE_LOWER                      BIT(30)
>> +
>> +#define ACTMON_ABOVE_WMARK_WINDOW                              1
>> +#define ACTMON_BELOW_WMARK_WINDOW                              3
>> +#define ACTMON_BOOST_FREQ_STEP                                 16000
>> +
>> +/* activity counter is incremented every 256 memory transactions, and each
>> + * transaction takes 4 EMC clocks for Tegra124; So the COUNT_WEIGHT is
>> + * 4 * 256 = 1024.
>> + */
>> +#define ACTMON_COUNT_WEIGHT                                    0x400
>> +
>> +/*
>> + * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which
>> + * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128
>> + */
>> +#define ACTMON_AVERAGE_WINDOW_LOG2                     6
>> +#define ACTMON_SAMPLING_PERIOD                         12 /* ms */
>> +#define ACTMON_DEFAULT_AVG_BAND                                6  /* 1/10 of % */
>> +
>> +#define KHZ                                                    1000
>> +
>> +/* Assume that the bus is saturated if the utilization is 25% */
>> +#define BUS_SATURATION_RATIO                                   25
>> +
>> +/**
>> + * struct tegra_devfreq_device_config - configuration specific to an ACTMON
>> + * device
>> + *
>> + * Coefficients and thresholds are in %
>
> Short comments about what the members are for would be perfect (same
> for other structures). It is not immediatly obvious what e.g.
> avg_dependency_threshold is for.

Fair enough.

>> + */
>> +struct tegra_devfreq_device_config {
>> +       u32             offset;
>> +       u32             irq_mask;
>> +
>> +       unsigned int    boost_up_coeff;
>> +       unsigned int    boost_down_coeff;
>> +       unsigned int    boost_up_threshold;
>> +       unsigned int    boost_down_threshold;
>> +       u32             avg_dependency_threshold;
>> +};
>> +
>> +enum tegra_actmon_device {
>> +       MCALL = 0,
>> +       MCCPU,
>> +};
>> +
>> +static struct tegra_devfreq_device_config actmon_device_configs[] = {
>> +       {
>> +               /* MCALL */
>> +               .offset = 0x1c0,
>> +               .irq_mask = 1 << 26,
>> +               .boost_up_coeff = 200,
>> +               .boost_down_coeff = 50,
>> +               .boost_up_threshold = 60,
>> +               .boost_down_threshold = 40,
>> +       },
>> +       {
>> +               /* MCCPU */
>> +               .offset = 0x200,
>> +               .irq_mask = 1 << 25,
>> +               .boost_up_coeff = 800,
>> +               .boost_down_coeff = 90,
>> +               .boost_up_threshold = 27,
>> +               .boost_down_threshold = 10,
>> +               .avg_dependency_threshold = 50000,
>
> The boost_* and avg_dependency_threshold parameters are calling to be
> exported through debugfs in some future patch. :)
>
> Just for my education, why do we need to monitor both MCALL and MCCPU,
> since MCCPU accesses are included in MCALL? Do we want to boost things
> differently in case of CPU activity?

Yeah, I started by using only MCALL and found that performance
decreased substantially in scenarios with high CPU loads. Once I took
into account CPU frequency and the MCCPU counters as per downstream,
performance improved greatly.

I cannot tell why MCALL isn't enough though, maybe you can find a
fellow NVIDIAn that knows about it? Couldn't find anything in the
public TRM about it.

>> +       },
>> +};
>> +
>> +/**
>> + * struct tegra_devfreq_device - state specific to an ACTMON device
>> + *
>> + * Frequencies are in kHz.
>> + */
>> +struct tegra_devfreq_device {
>> +       const struct tegra_devfreq_device_config *config;
>> +
>> +       void __iomem    *regs;
>> +       u32             avg_band_freq;
>> +       u32             avg_count;
>> +
>> +       unsigned long   target_freq;
>> +       unsigned long   boost_freq;
>> +};
>> +
>> +struct tegra_devfreq {
>> +       struct devfreq          *devfreq;
>> +
>> +       struct platform_device  *pdev;
>> +       struct reset_control    *reset;
>> +       struct clk              *clock;
>> +       void __iomem            *regs;
>> +
>> +       spinlock_t              lock;
>> +
>> +       struct clk              *emc_clock;
>> +       unsigned long           max_freq;
>> +       unsigned long           cur_freq;
>> +       struct notifier_block   rate_change_nb;
>> +
>> +       struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
>> +};
>> +
>> +struct tegra_actmon_emc_ratio {
>> +       unsigned long cpu_freq;
>> +       unsigned long emc_freq;
>> +};
>> +
>> +static struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
>> +       { 1400000, ULONG_MAX },
>> +       { 1200000,    750000 },
>> +       { 1100000,    600000 },
>> +       { 1000000,    500000 },
>> +       {  800000,    375000 },
>> +       {  500000,    200000 },
>> +       {  250000,    100000 },
>
> Aren't these numbers board-specific? Should they be moved to the DT maybe?

I would expect it to be common to all boards with the same SoC.

>> +};
>> +
>> +static unsigned long do_percent(unsigned long val, unsigned int pct)
>> +{
>> +       return val * pct / 100;
>> +}
>> +
>> +static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq_device *dev)
>> +{
>> +       u32 avg = dev->avg_count;
>> +       u32 band = dev->avg_band_freq * ACTMON_SAMPLING_PERIOD;
>> +
>> +       writel(avg + band, dev->regs + ACTMON_DEV_AVG_UPPER_WMARK);
>
> Having actmon_readl() and actmon_writel() inline functions that make
> the "dev->regs +" unnecessary would be nicer to read and less
> error-prone IMHO.

Will try that.

>> +       avg = max(avg, band);
>> +       writel(avg - band, dev->regs + ACTMON_DEV_AVG_LOWER_WMARK);
>> +}
>> +
>> +static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
>> +                                      struct tegra_devfreq_device *dev)
>> +{
>> +       u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
>> +
>> +       writel(do_percent(val, dev->config->boost_up_threshold),
>> +              dev->regs + ACTMON_DEV_UPPER_WMARK);
>> +
>> +       writel(do_percent(val, dev->config->boost_down_threshold),
>> +              dev->regs + ACTMON_DEV_LOWER_WMARK);
>> +}
>> +
>> +static void actmon_write_barrier(struct tegra_devfreq *tegra)
>> +{
>> +       /* ensure the update has reached the ACTMON */
>> +       wmb();
>> +       readl(tegra->regs + ACTMON_GLB_STATUS);
>> +}
>> +
>> +static irqreturn_t actmon_isr(int irq, void *data)
>> +{
>> +       struct tegra_devfreq *tegra = data;
>> +       struct tegra_devfreq_device *dev = NULL;
>> +       unsigned long flags;
>> +       u32 val;
>> +       unsigned int i;
>> +
>> +       val = readl(tegra->regs + ACTMON_GLB_STATUS);
>> +
>> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
>> +               if (val & tegra->devices[i].config->irq_mask) {
>> +                       dev = tegra->devices + i;
>> +                       break;
>> +               }
>> +       }
>> +
>> +       if (!dev)
>> +               return IRQ_NONE;
>> +
>> +       spin_lock_irqsave(&tegra->lock, flags);
>> +
>> +       dev->avg_count = readl(dev->regs + ACTMON_DEV_AVG_COUNT);
>> +       tegra_devfreq_update_avg_wmark(dev);
>> +
>> +       val = readl(dev->regs + ACTMON_DEV_INTR_STATUS);
>> +       if (val & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) {
>> +               val = readl(dev->regs + ACTMON_DEV_CTRL) |
>> +                       ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN |
>> +                       ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
>> +
>> +               /*
>> +                * new_boost = min(old_boost * up_coef + step, max_freq)
>> +                */
>> +               dev->boost_freq = do_percent(dev->boost_freq,
>> +                                            dev->config->boost_up_coeff);
>> +               dev->boost_freq += ACTMON_BOOST_FREQ_STEP;
>> +               if (dev->boost_freq >= tegra->max_freq) {
>> +                       dev->boost_freq = tegra->max_freq;
>> +                       val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
>
> Instead of setting this flag to possibly remove it later, maybe set it
> only if this condition is not met?

That sounds better indeed, thanks.

>> +               }
>> +               writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +       } else if (val & ACTMON_DEV_INTR_CONSECUTIVE_LOWER) {
>> +               val = readl(dev->regs + ACTMON_DEV_CTRL) |
>> +                       ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN |
>> +                       ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
>> +
>> +               /*
>> +                * new_boost = old_boost * down_coef
>> +                * or 0 if (old_boost * down_coef < step / 2)
>> +                */
>> +               dev->boost_freq = do_percent(dev->boost_freq,
>> +                                            dev->config->boost_down_coeff);
>> +               if (dev->boost_freq < (ACTMON_BOOST_FREQ_STEP >> 1)) {
>> +                       dev->boost_freq = 0;
>> +                       val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
>
> Same here.
>
>> +               }
>> +               writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +       }
>> +
>> +       if (dev->config->avg_dependency_threshold) {
>> +               val = readl(dev->regs + ACTMON_DEV_CTRL);
>> +               if (dev->avg_count >= dev->config->avg_dependency_threshold)
>> +                       val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
>> +               else if (dev->boost_freq == 0)
>> +                       val &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
>> +               writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +       }
>> +
>> +       writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
>> +
>> +       actmon_write_barrier(tegra);
>> +
>> +       spin_unlock_irqrestore(&tegra->lock, flags);
>> +
>> +       return IRQ_WAKE_THREAD;
>> +}
>> +
>> +static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
>> +                                           unsigned long cpu_freq)
>> +{
>> +       unsigned int i;
>> +       struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
>> +
>> +       for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) {
>> +               if (cpu_freq >= ratio->cpu_freq) {
>> +                       if (ratio->emc_freq >= tegra->max_freq)
>> +                               return tegra->max_freq;
>> +                       else
>> +                               return ratio->emc_freq;
>> +               }
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static void actmon_update_target(struct tegra_devfreq *tegra,
>> +                                struct tegra_devfreq_device *dev)
>> +{
>> +       unsigned long cpu_freq = 0;
>> +       unsigned long static_cpu_emc_freq = 0;
>> +       unsigned int avg_sustain_coef;
>> +       unsigned long flags;
>> +
>> +       if (dev->config->avg_dependency_threshold) {
>> +               cpu_freq = cpufreq_get(0);
>> +               static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
>> +       }
>> +
>> +       spin_lock_irqsave(&tegra->lock, flags);
>> +
>> +       dev->target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
>> +       avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
>> +       dev->target_freq = do_percent(dev->target_freq, avg_sustain_coef);
>> +       dev->target_freq += dev->boost_freq;
>> +
>> +       if (dev->avg_count >= dev->config->avg_dependency_threshold)
>> +               dev->target_freq = max(dev->target_freq, static_cpu_emc_freq);
>> +
>> +       spin_unlock_irqrestore(&tegra->lock, flags);
>> +}
>> +
>> +static irqreturn_t actmon_thread_isr(int irq, void *data)
>> +{
>> +       struct tegra_devfreq *tegra = data;
>> +
>> +       mutex_lock(&tegra->devfreq->lock);
>> +       update_devfreq(tegra->devfreq);
>> +       mutex_unlock(&tegra->devfreq->lock);
>> +
>> +       return IRQ_HANDLED;
>> +}
>> +
>> +static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
>> +                                      unsigned long action, void *ptr)
>> +{
>> +       struct clk_notifier_data *data = ptr;
>> +       struct tegra_devfreq *tegra = container_of(nb, struct tegra_devfreq,
>> +                                                  rate_change_nb);
>> +       unsigned int i;
>> +       unsigned long flags;
>> +
>> +       spin_lock_irqsave(&tegra->lock, flags);
>> +
>> +       switch (action) {
>> +       case POST_RATE_CHANGE:
>> +               tegra->cur_freq = data->new_rate / KHZ;
>> +
>> +               for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
>> +                       tegra_devfreq_update_wmark(tegra, tegra->devices + i);
>> +
>> +               actmon_write_barrier(tegra);
>> +               break;
>> +       case PRE_RATE_CHANGE:
>> +               /* fall through */
>> +       case ABORT_RATE_CHANGE:
>
> Can't you use "default:" here instead?

Yeah, this needs simplifying.

>> +               break;
>> +       };
>> +
>> +       spin_unlock_irqrestore(&tegra->lock, flags);
>> +
>> +       return NOTIFY_OK;
>> +}
>> +
>> +static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
>> +                                         struct tegra_devfreq_device *dev)
>> +{
>> +       u32 val;
>> +
>> +       dev->avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
>> +       dev->target_freq = tegra->cur_freq;
>> +
>> +       dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
>> +       writel(dev->avg_count, dev->regs + ACTMON_DEV_INIT_AVG);
>> +
>> +       tegra_devfreq_update_avg_wmark(dev);
>> +       tegra_devfreq_update_wmark(tegra, dev);
>> +
>> +       writel(ACTMON_COUNT_WEIGHT, dev->regs + ACTMON_DEV_COUNT_WEIGHT);
>> +       writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
>> +
>> +       val = 0;
>> +       val |= ACTMON_DEV_CTRL_ENB_PERIODIC |
>> +              ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN |
>> +              ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
>> +       val |= (ACTMON_AVERAGE_WINDOW_LOG2 - 1)
>> +               << ACTMON_DEV_CTRL_K_VAL_SHIFT;
>> +       val |= (ACTMON_BELOW_WMARK_WINDOW - 1)
>> +               << ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT;
>> +       val |= (ACTMON_ABOVE_WMARK_WINDOW - 1)
>> +               << ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
>> +       val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN |
>> +              ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
>> +
>> +       writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +
>> +       actmon_write_barrier(tegra);
>> +
>> +       val = readl(dev->regs + ACTMON_DEV_CTRL);
>> +       val |= ACTMON_DEV_CTRL_ENB;
>> +       writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +
>> +       actmon_write_barrier(tegra);
>> +}
>> +
>> +static int tegra_devfreq_suspend(struct device *dev)
>> +{
>> +       struct platform_device *pdev;
>> +       struct tegra_devfreq *tegra;
>> +       struct tegra_devfreq_device *actmon_dev;
>> +       unsigned int i;
>> +       u32 val;
>> +
>> +       pdev = container_of(dev, struct platform_device, dev);
>> +       tegra = platform_get_drvdata(pdev);
>> +
>> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
>> +               actmon_dev = &tegra->devices[i];
>> +
>> +               val = readl(actmon_dev->regs + ACTMON_DEV_CTRL);
>> +               val &= ~ACTMON_DEV_CTRL_ENB;
>> +               writel(val, actmon_dev->regs + ACTMON_DEV_CTRL);
>> +
>> +               writel(ACTMON_INTR_STATUS_CLEAR,
>> +                      actmon_dev->regs + ACTMON_DEV_INTR_STATUS);
>> +
>> +               actmon_write_barrier(tegra);
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static int tegra_devfreq_resume(struct device *dev)
>> +{
>> +       struct platform_device *pdev;
>> +       struct tegra_devfreq *tegra;
>> +       struct tegra_devfreq_device *actmon_dev;
>> +       unsigned int i;
>> +
>> +       pdev = container_of(dev, struct platform_device, dev);
>> +       tegra = platform_get_drvdata(pdev);
>> +
>> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
>> +               actmon_dev = &tegra->devices[i];
>> +
>> +               tegra_actmon_configure_device(tegra, actmon_dev);
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>> +                               u32 flags)
>> +{
>> +       struct platform_device *pdev;
>> +       struct tegra_devfreq *tegra;
>> +       struct dev_pm_opp *opp;
>> +       unsigned long rate = *freq * KHZ;
>> +
>> +       pdev = container_of(dev, struct platform_device, dev);
>> +       tegra = platform_get_drvdata(pdev);
>> +
>> +       rcu_read_lock();
>> +       opp = devfreq_recommended_opp(dev, &rate, flags);
>> +       if (IS_ERR(opp)) {
>> +               rcu_read_unlock();
>> +               dev_err(dev, "Failed to find opp for %lu KHz\n", *freq);
>> +               return PTR_ERR(opp);
>> +       }
>> +       rate = dev_pm_opp_get_freq(opp);
>> +       rcu_read_unlock();
>> +
>> +       /* TODO: Once we have per-user clk constraints, set a floor */
>> +       clk_set_rate(tegra->emc_clock, rate);
>> +
>> +       /* TODO: Set voltage as well */
>> +
>> +       return 0;
>> +}
>> +
>> +static int tegra_devfreq_get_dev_status(struct device *dev,
>> +                                       struct devfreq_dev_status *stat)
>> +{
>> +       struct platform_device *pdev;
>> +       struct tegra_devfreq *tegra;
>> +       struct tegra_devfreq_device *actmon_dev;
>> +
>> +       pdev = container_of(dev, struct platform_device, dev);
>> +       tegra = platform_get_drvdata(pdev);
>> +
>> +       stat->current_frequency = tegra->cur_freq;
>> +
>> +       /* To be used by the tegra governor */
>> +       stat->private_data = tegra;
>> +
>> +       /* The below are to be used by the other governors */
>> +
>> +       actmon_dev = &tegra->devices[MCALL];
>> +
>> +       /* Number of cycles spent on memory access */
>> +       stat->busy_time = actmon_dev->avg_count;
>> +
>> +       /* The bus can be considered to be saturated way before 100% */
>> +       stat->busy_time *= 100 / BUS_SATURATION_RATIO;
>> +
>> +       /* Number of cycles in a sampling period */
>> +       stat->total_time = ACTMON_SAMPLING_PERIOD * tegra->cur_freq;
>> +
>> +       return 0;
>> +}
>> +
>> +static int tegra_devfreq_get_target(struct devfreq *devfreq,
>> +                                   unsigned long *freq)
>> +{
>> +       struct devfreq_dev_status stat;
>> +       struct tegra_devfreq *tegra;
>> +       struct tegra_devfreq_device *dev;
>> +       unsigned long target_freq = 0;
>> +       unsigned int i;
>> +       int err;
>> +
>> +       err = devfreq->profile->get_dev_status(devfreq->dev.parent, &stat);
>> +       if (err)
>> +               return err;
>> +
>> +       tegra = stat.private_data;
>> +
>> +       for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
>> +               dev = &tegra->devices[i];
>> +
>> +               actmon_update_target(tegra, dev);
>> +
>> +               target_freq = max(target_freq, dev->target_freq);
>> +       }
>
> I *think* you should be able to remove the dependency on
> tegra_devfreq_device from this function (ideally, governors should be
> device-agnostic). Since you call get_dev_status() from this function
> anyway, why not moving the actmon_update_target() calls into
> tegra_devfreq_get_dev_status(), and write busy_time/total_time values
> that will make tegra_devfreq_get_target() infer the right frequency?
>
>> +
>> +       *freq = target_freq;
>> +
>> +       return 0;
>> +}
>> +
>> +static int tegra_devfreq_event_handler(struct devfreq *devfreq,
>> +                                      unsigned int event, void *data)
>> +{
>> +       return 0;
>> +}
>
> I think you will need an implementation of this. Upon
> DEVFREQ_GOV_START/DEVFREQ_GOV_RESUME, enable actmon interrupts. On
> DEVFREQ_GOV_STOP/DEVFREQ_GOV_SUSPEND, disable interrupts. I know you
> are doing it somewhere, but it should be done here as this is what
> devfreq expects (e.g. to correctly stop interrupts if you switch from
> the "tegra" to the "performance" governor).
>
> Sadly, this adds the exact same dependency on tegra_devfreq that I
> tried to remove from the previous function, which is unfortunate. This
> is where watermarking support in devfreq would be useful - when
> starting the governor, we could ask the device to monitor some low and
> high marks through new hooks and handle all this nicely.

Wonder if the devfreq maintainers have an opinion on this.

>> +
>> +static struct devfreq_governor tegra_devfreq_governor = {
>> +       .name = "tegra",
>
> This governor could certainly get a more specific name. :P

Fair.

>> +       .get_target_freq = tegra_devfreq_get_target,
>> +       .event_handler = tegra_devfreq_event_handler,
>> +};
>> +
>> +static struct devfreq_dev_profile tegra_devfreq_profile = {
>> +       .polling_ms     = 0,
>> +       .target         = tegra_devfreq_target,
>> +       .get_dev_status = tegra_devfreq_get_dev_status,
>> +};
>
> Maybe move this declaration right after the declaration of
> tegra_devfreq_get_dev_status() to make things easier to put together
> in the reader's mind.

Agreed.

>> +
>> +static int tegra_devfreq_probe(struct platform_device *pdev)
>> +{
>> +       struct tegra_devfreq *tegra;
>> +       struct tegra_devfreq_device *dev;
>> +       struct resource *res;
>> +       unsigned long max_freq;
>> +       unsigned int i;
>> +       int irq;
>> +       int err;
>> +
>> +       tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
>> +       if (!tegra)
>> +               return -ENOMEM;
>> +
>> +       spin_lock_init(&tegra->lock);
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       if (!res) {
>> +               dev_err(&pdev->dev, "Failed to get regs resource\n");
>> +               return -ENODEV;
>> +       }
>> +
>> +       tegra->regs = devm_ioremap_resource(&pdev->dev, res);
>> +       if (IS_ERR(tegra->regs)) {
>> +               dev_err(&pdev->dev, "Failed to get IO memory\n");
>> +               return PTR_ERR(tegra->regs);
>> +       }
>> +
>> +       tegra->reset = devm_reset_control_get(&pdev->dev, "actmon");
>> +       if (IS_ERR(tegra->reset)) {
>> +               dev_err(&pdev->dev, "Failed to get reset\n");
>> +               return PTR_ERR(tegra->reset);
>> +       }
>> +
>> +       tegra->clock = devm_clk_get(&pdev->dev, "actmon");
>> +       if (IS_ERR(tegra->clock)) {
>> +               dev_err(&pdev->dev, "Failed to get actmon clock\n");
>> +               return PTR_ERR(tegra->clock);
>> +       }
>> +
>> +       tegra->emc_clock = devm_clk_get(&pdev->dev, "emc");
>> +       if (IS_ERR(tegra->emc_clock)) {
>> +               dev_err(&pdev->dev, "Failed to get emc clock\n");
>> +               return PTR_ERR(tegra->emc_clock);
>> +       }
>> +
>> +       err = of_init_opp_table(&pdev->dev);
>> +       if (err) {
>> +               dev_err(&pdev->dev, "Failed to init operating point table\n");
>> +               return err;
>> +       }
>> +
>> +       tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
>> +       err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
>> +       if (err) {
>> +               dev_err(&pdev->dev,
>> +                       "Failed to register rate change notifier\n");
>> +               return err;
>> +       }
>> +
>> +       reset_control_assert(tegra->reset);
>> +
>> +       err = clk_prepare_enable(tegra->clock);
>> +       if (err) {
>> +               reset_control_deassert(tegra->reset);
>> +               return err;
>> +       }
>> +
>> +       reset_control_deassert(tegra->reset);
>> +
>> +       max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX);
>> +       tegra->max_freq = max_freq / KHZ;
>> +
>> +       clk_set_rate(tegra->emc_clock, max_freq);
>> +
>> +       tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
>> +
>> +       writel(ACTMON_SAMPLING_PERIOD - 1,
>> +              tegra->regs + ACTMON_GLB_PERIOD_CTRL);
>> +
>> +       for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
>> +               dev = tegra->devices + i;
>> +               dev->config = actmon_device_configs + i;
>> +               dev->regs = tegra->regs + dev->config->offset;
>> +
>> +               tegra_actmon_configure_device(tegra, tegra->devices + i);
>> +       }
>> +
>> +       err = devfreq_add_governor(&tegra_devfreq_governor);
>
> This should probably be done in an initcall (that would be executed
> before probe() is called). We can in theory have several instances of
> ACTMON, but the governor should only be added once in all cases. I
> understand that this is unlikely to happen in practice though.

Will look at this.

>> +       if (err) {
>> +               dev_err(&pdev->dev, "Failed to add governor\n");
>> +               return err;
>> +       }
>> +
>> +       tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
>> +       tegra->devfreq = devm_devfreq_add_device(&pdev->dev,
>> +                                                &tegra_devfreq_profile,
>> +                                                "tegra",
>
> I think "tegra_actmon" would look better here. :)

Agreed.

>> +                                                NULL);
>> +
>> +       irq = platform_get_irq(pdev, 0);
>> +       err = devm_request_threaded_irq(&pdev->dev, irq, actmon_isr,
>> +                                       actmon_thread_isr, IRQF_SHARED,
>> +                                       "tegra-devfreq", tegra);
>
> You probably ought to do this *before* adding the devfreq device,
> otherwise you are at risk of receiving interrupts nobody will handle.

I don't get this one. The IRQ is requested as soon as everything is in
place to handle it.

>> +       if (err) {
>> +               dev_err(&pdev->dev, "Interrupt request failed\n");
>> +               return err;
>> +       }
>> +
>> +       platform_set_drvdata(pdev, tegra);
>
> This should also be done before the call to devfreq_add_device().

Shouldn't this be done between devfreq_add_device and
devm_request_threaded_irq? Guess I'm missing something.

>> +
>> +       return 0;
>> +}
>> +
>> +static int tegra_devfreq_remove(struct platform_device *pdev)
>> +{
>> +       struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
>> +
>> +       clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
>> +
>> +       clk_disable_unprepare(tegra->clock);
>
> There seems to be a lot missing in this function, like removing the
> devfreq device?

Those resources are managed, so devm should take care of releasing them.

Thanks,

Tomeu

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Re: [PATCH v2 2/3] PM / devfreq: tegra: add devfreq driver for Tegra Activity Monitor

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 13243 bytes --]

On Mon, Nov 24, 2014 at 01:28:17PM +0100, Tomeu Vizoso wrote:
> The ACTMON block can monitor several counters, providing averaging and firing
> interrupts based on watermarking configuration. This implementation monitors
> the MCALL and MCCPU counters to choose an appropriate frequency for the
> external memory clock.
> 
> This patch is based on work by Alex Frid <afrid@nvidia.com> and Mikko
> Perttunen <mikko.perttunen@kapsi.fi>.
> 
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> 
> ---
> 
> v2:	* Use devfreq
> ---
>  drivers/devfreq/Kconfig         |  10 +
>  drivers/devfreq/Makefile        |   1 +
>  drivers/devfreq/tegra-devfreq.c | 718 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 729 insertions(+)
>  create mode 100644 drivers/devfreq/tegra-devfreq.c
> 
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index faf4e70..4aab799 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -87,4 +87,14 @@ config ARM_EXYNOS5_BUS_DEVFREQ
>  	  It reads PPMU counters of memory controllers and adjusts the
>  	  operating frequencies and voltages with OPP support.
>  
> +config ARM_TEGRA_DEVFREQ
> +       tristate "Tegra DEVFREQ Driver"
> +       depends on ARCH_TEGRA_124_SOC

I think ACTMON exists at least on Tegra30 and Tegra114 as well and it
would be surprising if it didn't exist on Tegra132, so perhaps make this
dependency simply ARCH_TEGRA?

> +       select DEVFREQ_GOV_SIMPLE_ONDEMAND
> +       select PM_OPP
> +       help
> +         This adds the DEVFREQ driver for the Tegra family of SoCs.
> +         It reads ACTMON counters of memory controllers and adjusts the
> +         operating frequencies and voltages with OPP support.
> +
>  endif # PM_DEVFREQ
> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> index 16138c9..0ea991f 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
>  # DEVFREQ Drivers
>  obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)	+= exynos/
>  obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)	+= exynos/
> +obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
> diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
> new file mode 100644
> index 0000000..3479096
> --- /dev/null
> +++ b/drivers/devfreq/tegra-devfreq.c
> @@ -0,0 +1,718 @@
> +/*
> + * A devfreq driver for NVIDIA Tegra SoCs
> + *
> + * Copyright (c) 2014 NVIDIA CORPORATION. All rights reserved.
> + * Copyright (C) 2014 Google, Inc
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
[...]
> +/* activity counter is incremented every 256 memory transactions, and each

Proper block-comments should be:

	/*
	 * activity counter...
	 * ...
	 */

Also it's a sentence, therefore should start with a capital 'A'.

> + * transaction takes 4 EMC clocks for Tegra124; So the COUNT_WEIGHT is
> + * 4 * 256 = 1024.
> + */
> +#define ACTMON_COUNT_WEIGHT					0x400
> +
> +/*
> + * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which
> + * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128
> + */
> +#define ACTMON_AVERAGE_WINDOW_LOG2			6
> +#define ACTMON_SAMPLING_PERIOD				12 /* ms */
> +#define ACTMON_DEFAULT_AVG_BAND				6  /* 1/10 of % */
> +
> +#define KHZ							1000
> +
> +/* Assume that the bus is saturated if the utilization is 25% */
> +#define BUS_SATURATION_RATIO					25
[...]
> +static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
> +					  struct tegra_devfreq_device *dev)
> +{
> +	u32 val;
> +
> +	dev->avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
> +	dev->target_freq = tegra->cur_freq;
> +
> +	dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
> +	writel(dev->avg_count, dev->regs + ACTMON_DEV_INIT_AVG);
> +
> +	tegra_devfreq_update_avg_wmark(dev);
> +	tegra_devfreq_update_wmark(tegra, dev);
> +
> +	writel(ACTMON_COUNT_WEIGHT, dev->regs + ACTMON_DEV_COUNT_WEIGHT);
> +	writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
> +
> +	val = 0;

You could initialize this to 0 and then save this one line.

> +	val |= ACTMON_DEV_CTRL_ENB_PERIODIC |
> +	       ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN |
> +	       ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
> +	val |= (ACTMON_AVERAGE_WINDOW_LOG2 - 1)
> +		<< ACTMON_DEV_CTRL_K_VAL_SHIFT;
> +	val |= (ACTMON_BELOW_WMARK_WINDOW - 1)
> +		<< ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT;
> +	val |= (ACTMON_ABOVE_WMARK_WINDOW - 1)
> +		<< ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
> +	val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN |
> +	       ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
> +
> +	writel(val, dev->regs + ACTMON_DEV_CTRL);
> +
> +	actmon_write_barrier(tegra);
> +
> +	val = readl(dev->regs + ACTMON_DEV_CTRL);
> +	val |= ACTMON_DEV_CTRL_ENB;
> +	writel(val, dev->regs + ACTMON_DEV_CTRL);
> +
> +	actmon_write_barrier(tegra);
> +}
> +
> +static int tegra_devfreq_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev;
> +	struct tegra_devfreq *tegra;
> +	struct tegra_devfreq_device *actmon_dev;
> +	unsigned int i;
> +	u32 val;
> +
> +	pdev = container_of(dev, struct platform_device, dev);
> +	tegra = platform_get_drvdata(pdev);

This is equivalent to just:

	struct tegra_devfreq *tegra = dev_get_drvdata(dev);

which you can then simply put at the top of the local variable
declarations.

> +
> +	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> +		actmon_dev = &tegra->devices[i];
> +
> +		val = readl(actmon_dev->regs + ACTMON_DEV_CTRL);
> +		val &= ~ACTMON_DEV_CTRL_ENB;
> +		writel(val, actmon_dev->regs + ACTMON_DEV_CTRL);
> +
> +		writel(ACTMON_INTR_STATUS_CLEAR,
> +		       actmon_dev->regs + ACTMON_DEV_INTR_STATUS);

Why do you need to clear pending interrupts on suspend? Isn't this going
to cause pending ones to be missed upon resume?

> +
> +		actmon_write_barrier(tegra);
> +	}
> +
> +	return 0;
> +}
> +
> +static int tegra_devfreq_resume(struct device *dev)
> +{
> +	struct platform_device *pdev;
> +	struct tegra_devfreq *tegra;
> +	struct tegra_devfreq_device *actmon_dev;
> +	unsigned int i;
> +
> +	pdev = container_of(dev, struct platform_device, dev);
> +	tegra = platform_get_drvdata(pdev);

Same here. And in a few other places as well.

> +
> +	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> +		actmon_dev = &tegra->devices[i];
> +
> +		tegra_actmon_configure_device(tegra, actmon_dev);
> +	}
> +
> +	return 0;
> +}

You'll want to protect the tegra_devfreq_{suspend,resume}() with an
#ifdef CONFIG_PM_SLEEP to avoid potential build warnings (in randconfig
builds for example).

These are also somewhat oddly placed. Perhaps move them below
tegra_devfreq_remove() for more natural ordering?

> +static int tegra_devfreq_probe(struct platform_device *pdev)
> +{
> +	struct tegra_devfreq *tegra;
> +	struct tegra_devfreq_device *dev;
> +	struct resource *res;
> +	unsigned long max_freq;
> +	unsigned int i;
> +	int irq;
> +	int err;
> +
> +	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
> +	if (!tegra)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&tegra->lock);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(&pdev->dev, "Failed to get regs resource\n");
> +		return -ENODEV;
> +	}

No need for this check, devm_ioremap_resource() does it for you.

> +
> +	tegra->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(tegra->regs)) {
> +		dev_err(&pdev->dev, "Failed to get IO memory\n");

No need for the error message either.

> +		return PTR_ERR(tegra->regs);
> +	}
> +
> +	tegra->reset = devm_reset_control_get(&pdev->dev, "actmon");
> +	if (IS_ERR(tegra->reset)) {
> +		dev_err(&pdev->dev, "Failed to get reset\n");
> +		return PTR_ERR(tegra->reset);
> +	}
> +
> +	tegra->clock = devm_clk_get(&pdev->dev, "actmon");
> +	if (IS_ERR(tegra->clock)) {
> +		dev_err(&pdev->dev, "Failed to get actmon clock\n");
> +		return PTR_ERR(tegra->clock);
> +	}
> +
> +	tegra->emc_clock = devm_clk_get(&pdev->dev, "emc");
> +	if (IS_ERR(tegra->emc_clock)) {
> +		dev_err(&pdev->dev, "Failed to get emc clock\n");
> +		return PTR_ERR(tegra->emc_clock);
> +	}
> +
> +	err = of_init_opp_table(&pdev->dev);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to init operating point table\n");
> +		return err;
> +	}
> +
> +	tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
> +	err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
> +	if (err) {
> +		dev_err(&pdev->dev,
> +			"Failed to register rate change notifier\n");
> +		return err;
> +	}
> +
> +	reset_control_assert(tegra->reset);
> +
> +	err = clk_prepare_enable(tegra->clock);
> +	if (err) {
> +		reset_control_deassert(tegra->reset);

I'm not so sure if it makes much sense to deassert reset when the driver
fails to probe.

> +		return err;
> +	}
> +
> +	reset_control_deassert(tegra->reset);
> +
> +	max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX);
> +	tegra->max_freq = max_freq / KHZ;
> +
> +	clk_set_rate(tegra->emc_clock, max_freq);
> +
> +	tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
> +
> +	writel(ACTMON_SAMPLING_PERIOD - 1,
> +	       tegra->regs + ACTMON_GLB_PERIOD_CTRL);
> +
> +	for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
> +		dev = tegra->devices + i;
> +		dev->config = actmon_device_configs + i;
> +		dev->regs = tegra->regs + dev->config->offset;
> +
> +		tegra_actmon_configure_device(tegra, tegra->devices + i);

The second parameter can simply be "dev" here, can't it?

> +	}
> +
> +	err = devfreq_add_governor(&tegra_devfreq_governor);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to add governor\n");
> +		return err;
> +	}
> +
> +	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
> +	tegra->devfreq = devm_devfreq_add_device(&pdev->dev,
> +						 &tegra_devfreq_profile,
> +						 "tegra",
> +						 NULL);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	err = devm_request_threaded_irq(&pdev->dev, irq, actmon_isr,
> +					actmon_thread_isr, IRQF_SHARED,
> +					"tegra-devfreq", tegra);
> +	if (err) {
> +		dev_err(&pdev->dev, "Interrupt request failed\n");
> +		return err;
> +	}
> +
> +	platform_set_drvdata(pdev, tegra);
> +
> +	return 0;
> +}
> +
> +static int tegra_devfreq_remove(struct platform_device *pdev)
> +{
> +	struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
> +
> +	clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
> +
> +	clk_disable_unprepare(tegra->clock);
> +
> +	return 0;
> +}

You'll need to be wary about using devm_request_threaded_irq(). You have
to make sure that the interrupt handler isn't accessing any data that
could be freed via the devres mechanism before the IRQ is freed. Given
that devres frees resources in the opposite order than they were
allocated, and given that you request the interrupt last it /should be/
safe.

Then again you do disable and unprepare the clock, so if you were to
access registers from the interrupt handler (called after clock disable
and before IRQ free) you could possibly cause a hang.

Often the simplest is to just explicitly call devm_free_irq() in your
.remove().

> +static SIMPLE_DEV_PM_OPS(tegra_devfreq_pm_ops,
> +			 tegra_devfreq_suspend,
> +			 tegra_devfreq_resume);
> +
> +static struct of_device_id tegra_devfreq_of_match[] = {
> +	{ .compatible = "nvidia,tegra124-actmon" },
> +	{ },
> +};
> +
> +static struct platform_driver tegra_devfreq_driver = {
> +	.probe	= tegra_devfreq_probe,
> +	.remove	= tegra_devfreq_remove,
> +	.driver = {
> +		.name		= "tegra-devfreq",
> +		.owner		= THIS_MODULE,

No need for this with module_platform_driver().

> +		.of_match_table = tegra_devfreq_of_match,
> +		.pm		= &tegra_devfreq_pm_ops,

Also you use tabs and spaces inconsistently here. I'd just get rid of
any attempt to align these and simply use a single space on either side
of the '='.

> +	},
> +};
> +module_platform_driver(tegra_devfreq_driver);
> +
> +MODULE_LICENSE("GPL");

According to the header comment this should be "GPL v2".

> +MODULE_DESCRIPTION("Tegra devfreq driver");
> +MODULE_AUTHOR("Tomeu Vizoso <tomeu.vizoso@collabora.com>");
> +MODULE_DEVICE_TABLE(of, tegra_devfreq_of_match);

I think it's more common to have this immediately below the OF match
table.

Thierry

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Re: [PATCH v2 2/3] PM / devfreq: tegra: add devfreq driver for Tegra Activity Monitor

[Tomeu Vizoso]

On 2 December 2014 at 12:15, Thierry Reding <thierry.reding@gmail.com> wrote:
> On Mon, Nov 24, 2014 at 01:28:17PM +0100, Tomeu Vizoso wrote:
>> The ACTMON block can monitor several counters, providing averaging and firing
>> interrupts based on watermarking configuration. This implementation monitors
>> the MCALL and MCCPU counters to choose an appropriate frequency for the
>> external memory clock.
>>
>> This patch is based on work by Alex Frid <afrid@nvidia.com> and Mikko
>> Perttunen <mikko.perttunen@kapsi.fi>.
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>>
>> ---
>>
>> v2:   * Use devfreq
>> ---
>>  drivers/devfreq/Kconfig         |  10 +
>>  drivers/devfreq/Makefile        |   1 +
>>  drivers/devfreq/tegra-devfreq.c | 718 ++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 729 insertions(+)
>>  create mode 100644 drivers/devfreq/tegra-devfreq.c
>>
>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
>> index faf4e70..4aab799 100644
>> --- a/drivers/devfreq/Kconfig
>> +++ b/drivers/devfreq/Kconfig
>> @@ -87,4 +87,14 @@ config ARM_EXYNOS5_BUS_DEVFREQ
>>         It reads PPMU counters of memory controllers and adjusts the
>>         operating frequencies and voltages with OPP support.
>>
>> +config ARM_TEGRA_DEVFREQ
>> +       tristate "Tegra DEVFREQ Driver"
>> +       depends on ARCH_TEGRA_124_SOC
>
> I think ACTMON exists at least on Tegra30 and Tegra114 as well and it
> would be surprising if it didn't exist on Tegra132, so perhaps make this
> dependency simply ARCH_TEGRA?

Ok.

>> +       select DEVFREQ_GOV_SIMPLE_ONDEMAND
>> +       select PM_OPP
>> +       help
>> +         This adds the DEVFREQ driver for the Tegra family of SoCs.
>> +         It reads ACTMON counters of memory controllers and adjusts the
>> +         operating frequencies and voltages with OPP support.
>> +
>>  endif # PM_DEVFREQ
>> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
>> index 16138c9..0ea991f 100644
>> --- a/drivers/devfreq/Makefile
>> +++ b/drivers/devfreq/Makefile
>> @@ -7,3 +7,4 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)   += governor_userspace.o
>>  # DEVFREQ Drivers
>>  obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)        += exynos/
>>  obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)        += exynos/
>> +obj-$(CONFIG_ARM_TEGRA_DEVFREQ)              += tegra-devfreq.o
>> diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
>> new file mode 100644
>> index 0000000..3479096
>> --- /dev/null
>> +++ b/drivers/devfreq/tegra-devfreq.c
>> @@ -0,0 +1,718 @@
>> +/*
>> + * A devfreq driver for NVIDIA Tegra SoCs
>> + *
>> + * Copyright (c) 2014 NVIDIA CORPORATION. All rights reserved.
>> + * Copyright (C) 2014 Google, Inc
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
>> + *
>> + */
>> +
> [...]
>> +/* activity counter is incremented every 256 memory transactions, and each
>
> Proper block-comments should be:
>
>         /*
>          * activity counter...
>          * ...
>          */
>
> Also it's a sentence, therefore should start with a capital 'A'.

Done.

>> + * transaction takes 4 EMC clocks for Tegra124; So the COUNT_WEIGHT is
>> + * 4 * 256 = 1024.
>> + */
>> +#define ACTMON_COUNT_WEIGHT                                  0x400
>> +
>> +/*
>> + * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which
>> + * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128
>> + */
>> +#define ACTMON_AVERAGE_WINDOW_LOG2                   6
>> +#define ACTMON_SAMPLING_PERIOD                               12 /* ms */
>> +#define ACTMON_DEFAULT_AVG_BAND                              6  /* 1/10 of % */
>> +
>> +#define KHZ                                                  1000
>> +
>> +/* Assume that the bus is saturated if the utilization is 25% */
>> +#define BUS_SATURATION_RATIO                                 25
> [...]
>> +static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
>> +                                       struct tegra_devfreq_device *dev)
>> +{
>> +     u32 val;
>> +
>> +     dev->avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
>> +     dev->target_freq = tegra->cur_freq;
>> +
>> +     dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
>> +     writel(dev->avg_count, dev->regs + ACTMON_DEV_INIT_AVG);
>> +
>> +     tegra_devfreq_update_avg_wmark(dev);
>> +     tegra_devfreq_update_wmark(tegra, dev);
>> +
>> +     writel(ACTMON_COUNT_WEIGHT, dev->regs + ACTMON_DEV_COUNT_WEIGHT);
>> +     writel(ACTMON_INTR_STATUS_CLEAR, dev->regs + ACTMON_DEV_INTR_STATUS);
>> +
>> +     val = 0;
>
> You could initialize this to 0 and then save this one line.

Cool.

>> +     val |= ACTMON_DEV_CTRL_ENB_PERIODIC |
>> +            ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN |
>> +            ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
>> +     val |= (ACTMON_AVERAGE_WINDOW_LOG2 - 1)
>> +             << ACTMON_DEV_CTRL_K_VAL_SHIFT;
>> +     val |= (ACTMON_BELOW_WMARK_WINDOW - 1)
>> +             << ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_NUM_SHIFT;
>> +     val |= (ACTMON_ABOVE_WMARK_WINDOW - 1)
>> +             << ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
>> +     val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN |
>> +            ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
>> +
>> +     writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +
>> +     actmon_write_barrier(tegra);
>> +
>> +     val = readl(dev->regs + ACTMON_DEV_CTRL);
>> +     val |= ACTMON_DEV_CTRL_ENB;
>> +     writel(val, dev->regs + ACTMON_DEV_CTRL);
>> +
>> +     actmon_write_barrier(tegra);
>> +}
>> +
>> +static int tegra_devfreq_suspend(struct device *dev)
>> +{
>> +     struct platform_device *pdev;
>> +     struct tegra_devfreq *tegra;
>> +     struct tegra_devfreq_device *actmon_dev;
>> +     unsigned int i;
>> +     u32 val;
>> +
>> +     pdev = container_of(dev, struct platform_device, dev);
>> +     tegra = platform_get_drvdata(pdev);
>
> This is equivalent to just:
>
>         struct tegra_devfreq *tegra = dev_get_drvdata(dev);
>
> which you can then simply put at the top of the local variable
> declarations.

Good, thanks.

>> +
>> +     for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
>> +             actmon_dev = &tegra->devices[i];
>> +
>> +             val = readl(actmon_dev->regs + ACTMON_DEV_CTRL);
>> +             val &= ~ACTMON_DEV_CTRL_ENB;
>> +             writel(val, actmon_dev->regs + ACTMON_DEV_CTRL);
>> +
>> +             writel(ACTMON_INTR_STATUS_CLEAR,
>> +                    actmon_dev->regs + ACTMON_DEV_INTR_STATUS);
>
> Why do you need to clear pending interrupts on suspend? Isn't this going
> to cause pending ones to be missed upon resume?

We are completely reconfiguring the ACTMON devices on resume, so I
think we want to ignore any pending interrupts.

>> +
>> +             actmon_write_barrier(tegra);
>> +     }
>> +
>> +     return 0;
>> +}
>> +
>> +static int tegra_devfreq_resume(struct device *dev)
>> +{
>> +     struct platform_device *pdev;
>> +     struct tegra_devfreq *tegra;
>> +     struct tegra_devfreq_device *actmon_dev;
>> +     unsigned int i;
>> +
>> +     pdev = container_of(dev, struct platform_device, dev);
>> +     tegra = platform_get_drvdata(pdev);
>
> Same here. And in a few other places as well.
>
>> +
>> +     for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
>> +             actmon_dev = &tegra->devices[i];
>> +
>> +             tegra_actmon_configure_device(tegra, actmon_dev);
>> +     }
>> +
>> +     return 0;
>> +}
>
> You'll want to protect the tegra_devfreq_{suspend,resume}() with an
> #ifdef CONFIG_PM_SLEEP to avoid potential build warnings (in randconfig
> builds for example).
>
> These are also somewhat oddly placed. Perhaps move them below
> tegra_devfreq_remove() for more natural ordering?

Good, thanks.

>> +static int tegra_devfreq_probe(struct platform_device *pdev)
>> +{
>> +     struct tegra_devfreq *tegra;
>> +     struct tegra_devfreq_device *dev;
>> +     struct resource *res;
>> +     unsigned long max_freq;
>> +     unsigned int i;
>> +     int irq;
>> +     int err;
>> +
>> +     tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
>> +     if (!tegra)
>> +             return -ENOMEM;
>> +
>> +     spin_lock_init(&tegra->lock);
>> +
>> +     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     if (!res) {
>> +             dev_err(&pdev->dev, "Failed to get regs resource\n");
>> +             return -ENODEV;
>> +     }
>
> No need for this check, devm_ioremap_resource() does it for you.
>
>> +
>> +     tegra->regs = devm_ioremap_resource(&pdev->dev, res);
>> +     if (IS_ERR(tegra->regs)) {
>> +             dev_err(&pdev->dev, "Failed to get IO memory\n");
>
> No need for the error message either.

Nice.

>> +             return PTR_ERR(tegra->regs);
>> +     }
>> +
>> +     tegra->reset = devm_reset_control_get(&pdev->dev, "actmon");
>> +     if (IS_ERR(tegra->reset)) {
>> +             dev_err(&pdev->dev, "Failed to get reset\n");
>> +             return PTR_ERR(tegra->reset);
>> +     }
>> +
>> +     tegra->clock = devm_clk_get(&pdev->dev, "actmon");
>> +     if (IS_ERR(tegra->clock)) {
>> +             dev_err(&pdev->dev, "Failed to get actmon clock\n");
>> +             return PTR_ERR(tegra->clock);
>> +     }
>> +
>> +     tegra->emc_clock = devm_clk_get(&pdev->dev, "emc");
>> +     if (IS_ERR(tegra->emc_clock)) {
>> +             dev_err(&pdev->dev, "Failed to get emc clock\n");
>> +             return PTR_ERR(tegra->emc_clock);
>> +     }
>> +
>> +     err = of_init_opp_table(&pdev->dev);
>> +     if (err) {
>> +             dev_err(&pdev->dev, "Failed to init operating point table\n");
>> +             return err;
>> +     }
>> +
>> +     tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
>> +     err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
>> +     if (err) {
>> +             dev_err(&pdev->dev,
>> +                     "Failed to register rate change notifier\n");
>> +             return err;
>> +     }
>> +
>> +     reset_control_assert(tegra->reset);
>> +
>> +     err = clk_prepare_enable(tegra->clock);
>> +     if (err) {
>> +             reset_control_deassert(tegra->reset);
>
> I'm not so sure if it makes much sense to deassert reset when the driver
> fails to probe.

Ok.

>> +             return err;
>> +     }
>> +
>> +     reset_control_deassert(tegra->reset);
>> +
>> +     max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX);
>> +     tegra->max_freq = max_freq / KHZ;
>> +
>> +     clk_set_rate(tegra->emc_clock, max_freq);
>> +
>> +     tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
>> +
>> +     writel(ACTMON_SAMPLING_PERIOD - 1,
>> +            tegra->regs + ACTMON_GLB_PERIOD_CTRL);
>> +
>> +     for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
>> +             dev = tegra->devices + i;
>> +             dev->config = actmon_device_configs + i;
>> +             dev->regs = tegra->regs + dev->config->offset;
>> +
>> +             tegra_actmon_configure_device(tegra, tegra->devices + i);
>
> The second parameter can simply be "dev" here, can't it?

You are right.

>> +     }
>> +
>> +     err = devfreq_add_governor(&tegra_devfreq_governor);
>> +     if (err) {
>> +             dev_err(&pdev->dev, "Failed to add governor\n");
>> +             return err;
>> +     }
>> +
>> +     tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
>> +     tegra->devfreq = devm_devfreq_add_device(&pdev->dev,
>> +                                              &tegra_devfreq_profile,
>> +                                              "tegra",
>> +                                              NULL);
>> +
>> +     irq = platform_get_irq(pdev, 0);
>> +     err = devm_request_threaded_irq(&pdev->dev, irq, actmon_isr,
>> +                                     actmon_thread_isr, IRQF_SHARED,
>> +                                     "tegra-devfreq", tegra);
>> +     if (err) {
>> +             dev_err(&pdev->dev, "Interrupt request failed\n");
>> +             return err;
>> +     }
>> +
>> +     platform_set_drvdata(pdev, tegra);
>> +
>> +     return 0;
>> +}
>> +
>> +static int tegra_devfreq_remove(struct platform_device *pdev)
>> +{
>> +     struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
>> +
>> +     clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
>> +
>> +     clk_disable_unprepare(tegra->clock);
>> +
>> +     return 0;
>> +}
>
> You'll need to be wary about using devm_request_threaded_irq(). You have
> to make sure that the interrupt handler isn't accessing any data that
> could be freed via the devres mechanism before the IRQ is freed. Given
> that devres frees resources in the opposite order than they were
> allocated, and given that you request the interrupt last it /should be/
> safe.
>
> Then again you do disable and unprepare the clock, so if you were to
> access registers from the interrupt handler (called after clock disable
> and before IRQ free) you could possibly cause a hang.
>
> Often the simplest is to just explicitly call devm_free_irq() in your
> .remove().

Thanks for the explanation.

>> +static SIMPLE_DEV_PM_OPS(tegra_devfreq_pm_ops,
>> +                      tegra_devfreq_suspend,
>> +                      tegra_devfreq_resume);
>> +
>> +static struct of_device_id tegra_devfreq_of_match[] = {
>> +     { .compatible = "nvidia,tegra124-actmon" },
>> +     { },
>> +};
>> +
>> +static struct platform_driver tegra_devfreq_driver = {
>> +     .probe  = tegra_devfreq_probe,
>> +     .remove = tegra_devfreq_remove,
>> +     .driver = {
>> +             .name           = "tegra-devfreq",
>> +             .owner          = THIS_MODULE,
>
> No need for this with module_platform_driver().

I see.

>> +             .of_match_table = tegra_devfreq_of_match,
>> +             .pm             = &tegra_devfreq_pm_ops,
>
> Also you use tabs and spaces inconsistently here. I'd just get rid of
> any attempt to align these and simply use a single space on either side
> of the '='.

Agreed.

>> +     },
>> +};
>> +module_platform_driver(tegra_devfreq_driver);
>> +
>> +MODULE_LICENSE("GPL");
>
> According to the header comment this should be "GPL v2".

Oops.

>> +MODULE_DESCRIPTION("Tegra devfreq driver");
>> +MODULE_AUTHOR("Tomeu Vizoso <tomeu.vizoso@collabora.com>");
>> +MODULE_DEVICE_TABLE(of, tegra_devfreq_of_match);
>
> I think it's more common to have this immediately below the OF match
> table.

Cool, thanks a lot!

Regards,

Tomeu

[PATCH v2 3/3] ARM: tegra: Add Tegra124 ACTMON support

[Tomeu Vizoso]

Add device node for the ACTMON block to the Tegra124 device tree.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>

---

v2:     * Add operating-points property
---
 arch/arm/boot/dts/tegra124.dtsi | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/arm/boot/dts/tegra124.dtsi b/arch/arm/boot/dts/tegra124.dtsi
index dfc476b..8b19f4c 100644
--- a/arch/arm/boot/dts/tegra124.dtsi
+++ b/arch/arm/boot/dts/tegra124.dtsi
@@ -215,6 +215,29 @@
 		reg = <0x0 0x60007000 0x0 0x1000>;
 	};
 
+	actmon@0,6000c800 {
+		compatible = "nvidia,tegra124-actmon";
+		reg = <0x0 0x6000c800 0x0 0x400>;
+		interrupts = <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&tegra_car TEGRA124_CLK_ACTMON>,
+			 <&tegra_car TEGRA124_CLK_EMC>;
+		clock-names = "actmon", "emc";
+		resets = <&tegra_car 119>;
+		reset-names = "actmon";
+		operating-points = <
+			/* KHz	uV */
+			/* TODO: Add more points below 102 MHz */
+			102000	800000
+			204000	800000
+			300000	820000
+			396000	850000
+			528000	880000
+			600000	910000
+			792000	980000
+			924000	1010000
+		>;
+	};
+
 	gpio: gpio@0,6000d000 {
 		compatible = "nvidia,tegra124-gpio", "nvidia,tegra30-gpio";
 		reg = <0x0 0x6000d000 0x0 0x1000>;
-- 
1.9.3