1 files changed, 718 insertions, 0 deletions

diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
new file mode 100644
index 000000000000..34790961af5a
--- /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);