drivers/devfreq/m4m-hwmon.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
  * only version 2 as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */

 #define pr_fmt(fmt) "m4m-hwmon: " fmt

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/spinlock.h>
 #include "governor_cache_hwmon.h"

 #define cntr_offset(idx) (sizeof(u32) * idx)

 /* register offsets from base address */
 #define DCVS_VERSION(m)		((m)->base + 0x0)
 #define GLOBAL_CR_CTL(m)	((m)->base + 0x8)
 #define GLOBAL_CR_RESET(m)	((m)->base + 0xC)
 #define OVSTAT(m)		((m)->base + 0x30)
 #define OVCLR(m)		((m)->base + 0x34)
 #define OVSET(m)		((m)->base + 0x3C) /* unused */
 #define EVCNTR(m, x)		((m)->base + 0x40 + cntr_offset(x))
 #define CNTCTL(m, x)		((m)->base + 0x100 + cntr_offset(x))
 /* counter 0/1 does not have type control */
 #define EVTYPER_START	2
 #define EVTYPER(x)	((m)->base + 0x140 + cntr_offset(x))

 /* bitmasks for GLOBAL_CR_CTL and CNTCTLx */
 #define CNT_EN	BIT(0)
 #define IRQ_EN	BIT(1)

 /* non-configurable counters */
 #define CYC_CNTR_IDX		0
 #define WASTED_CYC_CNTR_IDX	1

 /* counter is 28-bit */
 #define CNT_MAX 0x0FFFFFFFU

 struct m4m_counter {
 	int idx;
 	u32 event_mask;
 	unsigned int last_start;
 };

 struct m4m_hwmon {
 	void __iomem *base;
 	struct m4m_counter cntr[MAX_NUM_GROUPS];
 	int num_cntr;
 	int irq;
 	struct cache_hwmon hw;
 	struct device *dev;
 };

 #define to_mon(ptr) container_of(ptr, struct m4m_hwmon, hw)

 static DEFINE_SPINLOCK(init_lock);

 /* Should only be called once while HW is in POR state */
 static inline void mon_global_init(struct m4m_hwmon *m)
 {
 	writel_relaxed(CNT_EN | IRQ_EN, GLOBAL_CR_CTL(m));
 }

 static inline void _mon_disable_cntr_and_irq(struct m4m_hwmon *m, int cntr_idx)
 {
 	writel_relaxed(0, CNTCTL(m, cntr_idx));
 }

 static inline void _mon_enable_cntr_and_irq(struct m4m_hwmon *m, int cntr_idx)
 {
 	writel_relaxed(CNT_EN | IRQ_EN, CNTCTL(m, cntr_idx));
 }

 static void mon_disable(struct m4m_hwmon *m)
 {
 	int i;

 	for (i = 0; i < m->num_cntr; i++)
 		_mon_disable_cntr_and_irq(m, m->cntr[i].idx);
 	/* make sure all counter/irq are indeed disabled */
 	mb();
 }

 static void mon_enable(struct m4m_hwmon *m)
 {
 	int i;

 	for (i = 0; i < m->num_cntr; i++)
 		_mon_enable_cntr_and_irq(m, m->cntr[i].idx);
 }

 static inline void _mon_ov_clear(struct m4m_hwmon *m, int cntr_idx)
 {
 	writel_relaxed(BIT(cntr_idx), OVCLR(m));
 }

 static void mon_ov_clear(struct m4m_hwmon *m, enum request_group grp)
 {
 	_mon_ov_clear(m, m->cntr[grp].idx);
 }

 static inline u32 mon_irq_status(struct m4m_hwmon *m)
 {
 	return readl_relaxed(OVSTAT(m));
 }

 static bool mon_is_ovstat_set(struct m4m_hwmon *m)
 {
 	int i;
 	u32 status = mon_irq_status(m);

 	for (i = 0; i < m->num_cntr; i++)
 		if (status & BIT(m->cntr[i].idx))
 			return true;
 	return false;
 }

 /* counter must be stopped first */
 static unsigned long _mon_get_count(struct m4m_hwmon *m,
 				    int cntr_idx, unsigned int start)
 {
 	unsigned long cnt;
 	u32 cur_cnt = readl_relaxed(EVCNTR(m, cntr_idx));
 	u32 ov = readl_relaxed(OVSTAT(m)) & BIT(cntr_idx);

 	if (!ov && cur_cnt < start) {
 		dev_warn(m->dev, "Counter%d overflowed but not detected\n",
 			 cntr_idx);
 		ov = 1;
 	}

 	if (ov)
 		cnt = CNT_MAX - start + cur_cnt;
 	else
 		cnt = cur_cnt - start;

 	return cnt;
 }

 static unsigned long mon_get_count(struct m4m_hwmon *m,
 				   enum request_group grp)
 {
 	return _mon_get_count(m, m->cntr[grp].idx, m->cntr[grp].last_start);
 }

 static inline void mon_set_limit(struct m4m_hwmon *m, enum request_group grp,
 			  unsigned int limit)
 {
 	u32 start;

 	if (limit >= CNT_MAX)
 		limit = CNT_MAX;
 	start = CNT_MAX - limit;

 	writel_relaxed(start, EVCNTR(m, m->cntr[grp].idx));
 	m->cntr[grp].last_start = start;
 }

 static inline void mon_enable_cycle_cntr(struct m4m_hwmon *m)
 {
 	writel_relaxed(CNT_EN, CNTCTL(m, CYC_CNTR_IDX));
 }

 static inline void mon_disable_cycle_cntr(struct m4m_hwmon *m)
 {
 	_mon_disable_cntr_and_irq(m, CYC_CNTR_IDX);
 }

 static inline unsigned long mon_get_cycle_count(struct m4m_hwmon *m)
 {
 	return _mon_get_count(m, CYC_CNTR_IDX, 0);
 }

 static inline void mon_clear_cycle_cntr(struct m4m_hwmon *m)
 {
 	writel_relaxed(0, EVCNTR(m, CYC_CNTR_IDX));
 	_mon_ov_clear(m, CYC_CNTR_IDX);
 }

 static void mon_init(struct m4m_hwmon *m)
 {
 	static bool mon_inited;
 	unsigned long flags;
 	int i;

 	spin_lock_irqsave(&init_lock, flags);
 	if (!mon_inited)
 		mon_global_init(m);
 	spin_unlock_irqrestore(&init_lock, flags);

 	/* configure counter events */
 	for (i = 0; i < m->num_cntr; i++)
 		writel_relaxed(m->cntr[i].event_mask, EVTYPER(m->cntr[i].idx));
 }

 static irqreturn_t m4m_hwmon_intr_handler(int irq, void *dev)
 {
 	struct m4m_hwmon *m = dev;

 	if (mon_is_ovstat_set(m)) {
 		update_cache_hwmon(&m->hw);
 		return IRQ_HANDLED;
 	}
 	return IRQ_NONE;
 }

 static int count_to_mrps(unsigned long count, unsigned int us)
 {
 	do_div(count, us);
 	count++;
 	return count;
 }

 static unsigned int mrps_to_count(unsigned int mrps, unsigned int ms,
 				  unsigned int tolerance)
 {
 	mrps += tolerance;
 	mrps *= ms * USEC_PER_MSEC;
 	return mrps;
 }

 static unsigned long m4m_meas_mrps_and_set_irq(struct cache_hwmon *hw,
 		unsigned int tol, unsigned int us, struct mrps_stats *mrps)
 {
 	struct m4m_hwmon *m = to_mon(hw);
 	unsigned long count, cyc_count;
 	unsigned long f = hw->df->previous_freq;
 	unsigned int sample_ms = hw->df->profile->polling_ms;
 	int i;
 	u32 limit;

 	mon_disable(m);
 	mon_disable_cycle_cntr(m);

 	/* calculate mrps and set limit */
 	for (i = 0; i < m->num_cntr; i++) {
 		count = mon_get_count(m, i);
 		mrps->mrps[i] = count_to_mrps(count, us);
 		limit = mrps_to_count(mrps->mrps[i], sample_ms, tol);
 		mon_ov_clear(m, i);
 		mon_set_limit(m, i, limit);
 		dev_dbg(m->dev, "Counter[%d] count 0x%lx, limit 0x%x\n",
 			m->cntr[i].idx, count, limit);
 	}

 	/* get cycle count and calculate busy percent */
 	cyc_count = mon_get_cycle_count(m);
 	mrps->busy_percent = mult_frac(cyc_count, 1000, us) * 100 / f;
 	mon_clear_cycle_cntr(m);
 	dev_dbg(m->dev, "Cycle count 0x%lx\n", cyc_count);

 	/* re-enable monitor */
 	mon_enable(m);
 	mon_enable_cycle_cntr(m);

 	return 0;
 }

 static int m4m_start_hwmon(struct cache_hwmon *hw, struct mrps_stats *mrps)
 {
 	struct m4m_hwmon *m = to_mon(hw);
 	unsigned int sample_ms = hw->df->profile->polling_ms;
 	int ret, i;
 	u32 limit;

 	ret = request_threaded_irq(m->irq, NULL, m4m_hwmon_intr_handler,
 				  IRQF_ONESHOT | IRQF_SHARED,
 				  dev_name(m->dev), m);
 	if (ret) {
 		dev_err(m->dev, "Unable to register for irq\n");
 		return ret;
 	}

 	mon_init(m);
 	mon_disable(m);
 	mon_disable_cycle_cntr(m);
 	for (i = 0; i < m->num_cntr; i++) {
 		mon_ov_clear(m, i);
 		limit = mrps_to_count(mrps->mrps[i], sample_ms, 0);
 		mon_set_limit(m, i, limit);
 	}
 	mon_clear_cycle_cntr(m);
 	mon_enable(m);
 	mon_enable_cycle_cntr(m);

 	return 0;
 }

 static void m4m_stop_hwmon(struct cache_hwmon *hw)
 {
 	struct m4m_hwmon *m = to_mon(hw);
 	int i;

 	mon_disable(m);
 	free_irq(m->irq, m);
 	for (i = 0; i < m->num_cntr; i++)
 		mon_ov_clear(m, i);
 }

 /* device probe functions */
 static const struct of_device_id m4m_match_table[] = {
 	{ .compatible = "qcom,m4m-hwmon" },
 	{}
 };

 static int m4m_hwmon_parse_cntr(struct device *dev,
 				struct m4m_hwmon *m)
 {
 	u32 *data;
 	const char *prop_name = "qcom,counter-event-sel";
 	int ret, len, i;

 	if (!of_find_property(dev->of_node, prop_name, &len))
 		return -EINVAL;
 	len /= sizeof(*data);

 	if (len % 2 || len > MAX_NUM_GROUPS * 2)
 		return -EINVAL;

 	data = devm_kcalloc(dev, len, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 	ret = of_property_read_u32_array(dev->of_node, prop_name, data, len);
 	if (ret)
 		return ret;

 	len /= 2;
 	m->num_cntr = len;
 	for (i = 0; i < len; i++) {
 		/* disallow non-configurable counters */
 		if (data[i * 2] < EVTYPER_START)
 			return -EINVAL;
 		m->cntr[i].idx = data[i * 2];
 		m->cntr[i].event_mask = data[i * 2 + 1];
 	}

 	devm_kfree(dev, data);
 	return 0;
 }

 static int m4m_hwmon_driver_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct resource *res;
 	struct m4m_hwmon *m;
 	int ret;

 	m = devm_kzalloc(dev, sizeof(*m), GFP_KERNEL);
 	if (!m)
 		return -ENOMEM;
 	m->dev = dev;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		dev_err(dev, "base not found!\n");
 		return -EINVAL;
 	}
 	m->base = devm_ioremap(dev, res->start, resource_size(res));
 	if (!m->base)
 		return -ENOMEM;

 	m->irq = platform_get_irq(pdev, 0);
 	if (m->irq < 0) {
 		dev_err(dev, "Unable to get IRQ number\n");
 		return m->irq;
 	}

 	ret = m4m_hwmon_parse_cntr(dev, m);
 	if (ret) {
 		dev_err(dev, "Unable to parse counter events\n");
 		return ret;
 	}

 	m->hw.of_node = of_parse_phandle(dev->of_node, "qcom,target-dev", 0);
 	if (!m->hw.of_node)
 		return -EINVAL;
 	m->hw.start_hwmon = &m4m_start_hwmon;
 	m->hw.stop_hwmon = &m4m_stop_hwmon;
 	m->hw.meas_mrps_and_set_irq = &m4m_meas_mrps_and_set_irq;

 	ret = register_cache_hwmon(dev, &m->hw);
 	if (ret) {
 		dev_err(dev, "Dev BW hwmon registration failed\n");
 		return ret;
 	}

 	return 0;
 }

 static struct platform_driver m4m_hwmon_driver = {
 	.probe = m4m_hwmon_driver_probe,
 	.driver = {
 		.name = "m4m-hwmon",
 		.of_match_table = m4m_match_table,
 	},
 };

 module_platform_driver(m4m_hwmon_driver);
 MODULE_DESCRIPTION("M4M hardware monitor driver");
 MODULE_LICENSE("GPL v2");
	/*
	* Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 and
	* only version 2 as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*/

	#define pr_fmt(fmt) "m4m-hwmon: " fmt

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/spinlock.h>
	#include "governor_cache_hwmon.h"

	#define cntr_offset(idx) (sizeof(u32) * idx)

	/* register offsets from base address */
	#define DCVS_VERSION(m) ((m)->base + 0x0)
	#define GLOBAL_CR_CTL(m) ((m)->base + 0x8)
	#define GLOBAL_CR_RESET(m) ((m)->base + 0xC)
	#define OVSTAT(m) ((m)->base + 0x30)
	#define OVCLR(m) ((m)->base + 0x34)
	#define OVSET(m) ((m)->base + 0x3C) /* unused */
	#define EVCNTR(m, x) ((m)->base + 0x40 + cntr_offset(x))
	#define CNTCTL(m, x) ((m)->base + 0x100 + cntr_offset(x))
	/* counter 0/1 does not have type control */
	#define EVTYPER_START 2
	#define EVTYPER(x) ((m)->base + 0x140 + cntr_offset(x))

	/* bitmasks for GLOBAL_CR_CTL and CNTCTLx */
	#define CNT_EN BIT(0)
	#define IRQ_EN BIT(1)

	/* non-configurable counters */
	#define CYC_CNTR_IDX 0
	#define WASTED_CYC_CNTR_IDX 1

	/* counter is 28-bit */
	#define CNT_MAX 0x0FFFFFFFU

	struct m4m_counter {
	int idx;
	u32 event_mask;
	unsigned int last_start;
	};

	struct m4m_hwmon {
	void __iomem *base;
	struct m4m_counter cntr[MAX_NUM_GROUPS];
	int num_cntr;
	int irq;
	struct cache_hwmon hw;
	struct device *dev;
	};

	#define to_mon(ptr) container_of(ptr, struct m4m_hwmon, hw)

	static DEFINE_SPINLOCK(init_lock);

	/* Should only be called once while HW is in POR state */
	static inline void mon_global_init(struct m4m_hwmon *m)
	{
	writel_relaxed(CNT_EN \| IRQ_EN, GLOBAL_CR_CTL(m));
	}

	static inline void _mon_disable_cntr_and_irq(struct m4m_hwmon *m, int cntr_idx)
	{
	writel_relaxed(0, CNTCTL(m, cntr_idx));
	}

	static inline void _mon_enable_cntr_and_irq(struct m4m_hwmon *m, int cntr_idx)
	{
	writel_relaxed(CNT_EN \| IRQ_EN, CNTCTL(m, cntr_idx));
	}

	static void mon_disable(struct m4m_hwmon *m)
	{
	int i;

	for (i = 0; i < m->num_cntr; i++)
	_mon_disable_cntr_and_irq(m, m->cntr[i].idx);
	/* make sure all counter/irq are indeed disabled */
	mb();
	}

	static void mon_enable(struct m4m_hwmon *m)
	{
	int i;

	for (i = 0; i < m->num_cntr; i++)
	_mon_enable_cntr_and_irq(m, m->cntr[i].idx);
	}

	static inline void _mon_ov_clear(struct m4m_hwmon *m, int cntr_idx)
	{
	writel_relaxed(BIT(cntr_idx), OVCLR(m));
	}

	static void mon_ov_clear(struct m4m_hwmon *m, enum request_group grp)
	{
	_mon_ov_clear(m, m->cntr[grp].idx);
	}

	static inline u32 mon_irq_status(struct m4m_hwmon *m)
	{
	return readl_relaxed(OVSTAT(m));
	}

	static bool mon_is_ovstat_set(struct m4m_hwmon *m)
	{
	int i;
	u32 status = mon_irq_status(m);

	for (i = 0; i < m->num_cntr; i++)
	if (status & BIT(m->cntr[i].idx))
	return true;
	return false;
	}

	/* counter must be stopped first */
	static unsigned long _mon_get_count(struct m4m_hwmon *m,
	int cntr_idx, unsigned int start)
	{
	unsigned long cnt;
	u32 cur_cnt = readl_relaxed(EVCNTR(m, cntr_idx));
	u32 ov = readl_relaxed(OVSTAT(m)) & BIT(cntr_idx);

	if (!ov && cur_cnt < start) {
	dev_warn(m->dev, "Counter%d overflowed but not detected\n",
	cntr_idx);
	ov = 1;
	}

	if (ov)
	cnt = CNT_MAX - start + cur_cnt;
	else
	cnt = cur_cnt - start;

	return cnt;
	}

	static unsigned long mon_get_count(struct m4m_hwmon *m,
	enum request_group grp)
	{
	return _mon_get_count(m, m->cntr[grp].idx, m->cntr[grp].last_start);
	}

	static inline void mon_set_limit(struct m4m_hwmon *m, enum request_group grp,
	unsigned int limit)
	{
	u32 start;

	if (limit >= CNT_MAX)
	limit = CNT_MAX;
	start = CNT_MAX - limit;

	writel_relaxed(start, EVCNTR(m, m->cntr[grp].idx));
	m->cntr[grp].last_start = start;
	}

	static inline void mon_enable_cycle_cntr(struct m4m_hwmon *m)
	{
	writel_relaxed(CNT_EN, CNTCTL(m, CYC_CNTR_IDX));
	}

	static inline void mon_disable_cycle_cntr(struct m4m_hwmon *m)
	{
	_mon_disable_cntr_and_irq(m, CYC_CNTR_IDX);
	}

	static inline unsigned long mon_get_cycle_count(struct m4m_hwmon *m)
	{
	return _mon_get_count(m, CYC_CNTR_IDX, 0);
	}

	static inline void mon_clear_cycle_cntr(struct m4m_hwmon *m)
	{
	writel_relaxed(0, EVCNTR(m, CYC_CNTR_IDX));
	_mon_ov_clear(m, CYC_CNTR_IDX);
	}

	static void mon_init(struct m4m_hwmon *m)
	{
	static bool mon_inited;
	unsigned long flags;
	int i;

	spin_lock_irqsave(&init_lock, flags);
	if (!mon_inited)
	mon_global_init(m);
	spin_unlock_irqrestore(&init_lock, flags);

	/* configure counter events */
	for (i = 0; i < m->num_cntr; i++)
	writel_relaxed(m->cntr[i].event_mask, EVTYPER(m->cntr[i].idx));
	}

	static irqreturn_t m4m_hwmon_intr_handler(int irq, void *dev)
	{
	struct m4m_hwmon *m = dev;

	if (mon_is_ovstat_set(m)) {
	update_cache_hwmon(&m->hw);
	return IRQ_HANDLED;
	}
	return IRQ_NONE;
	}

	static int count_to_mrps(unsigned long count, unsigned int us)
	{
	do_div(count, us);
	count++;
	return count;
	}

	static unsigned int mrps_to_count(unsigned int mrps, unsigned int ms,
	unsigned int tolerance)
	{
	mrps += tolerance;
	mrps = ms USEC_PER_MSEC;
	return mrps;
	}

	static unsigned long m4m_meas_mrps_and_set_irq(struct cache_hwmon *hw,
	unsigned int tol, unsigned int us, struct mrps_stats *mrps)
	{
	struct m4m_hwmon *m = to_mon(hw);
	unsigned long count, cyc_count;
	unsigned long f = hw->df->previous_freq;
	unsigned int sample_ms = hw->df->profile->polling_ms;
	int i;
	u32 limit;

	mon_disable(m);
	mon_disable_cycle_cntr(m);

	/* calculate mrps and set limit */
	for (i = 0; i < m->num_cntr; i++) {
	count = mon_get_count(m, i);
	mrps->mrps[i] = count_to_mrps(count, us);
	limit = mrps_to_count(mrps->mrps[i], sample_ms, tol);
	mon_ov_clear(m, i);
	mon_set_limit(m, i, limit);
	dev_dbg(m->dev, "Counter[%d] count 0x%lx, limit 0x%x\n",
	m->cntr[i].idx, count, limit);
	}

	/* get cycle count and calculate busy percent */
	cyc_count = mon_get_cycle_count(m);
	mrps->busy_percent = mult_frac(cyc_count, 1000, us) * 100 / f;
	mon_clear_cycle_cntr(m);
	dev_dbg(m->dev, "Cycle count 0x%lx\n", cyc_count);

	/* re-enable monitor */
	mon_enable(m);
	mon_enable_cycle_cntr(m);

	return 0;
	}

	static int m4m_start_hwmon(struct cache_hwmon hw, struct mrps_stats mrps)
	{
	struct m4m_hwmon *m = to_mon(hw);
	unsigned int sample_ms = hw->df->profile->polling_ms;
	int ret, i;
	u32 limit;

	ret = request_threaded_irq(m->irq, NULL, m4m_hwmon_intr_handler,
	IRQF_ONESHOT \| IRQF_SHARED,
	dev_name(m->dev), m);
	if (ret) {
	dev_err(m->dev, "Unable to register for irq\n");
	return ret;
	}

	mon_init(m);
	mon_disable(m);
	mon_disable_cycle_cntr(m);
	for (i = 0; i < m->num_cntr; i++) {
	mon_ov_clear(m, i);
	limit = mrps_to_count(mrps->mrps[i], sample_ms, 0);
	mon_set_limit(m, i, limit);
	}
	mon_clear_cycle_cntr(m);
	mon_enable(m);
	mon_enable_cycle_cntr(m);

	return 0;
	}

	static void m4m_stop_hwmon(struct cache_hwmon *hw)
	{
	struct m4m_hwmon *m = to_mon(hw);
	int i;

	mon_disable(m);
	free_irq(m->irq, m);
	for (i = 0; i < m->num_cntr; i++)
	mon_ov_clear(m, i);
	}

	/* device probe functions */
	static const struct of_device_id m4m_match_table[] = {
	{ .compatible = "qcom,m4m-hwmon" },
	{}
	};

	static int m4m_hwmon_parse_cntr(struct device *dev,
	struct m4m_hwmon *m)
	{
	u32 *data;
	const char *prop_name = "qcom,counter-event-sel";
	int ret, len, i;

	if (!of_find_property(dev->of_node, prop_name, &len))
	return -EINVAL;
	len /= sizeof(*data);

	if (len % 2 \|\| len > MAX_NUM_GROUPS * 2)
	return -EINVAL;

	data = devm_kcalloc(dev, len, sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;
	ret = of_property_read_u32_array(dev->of_node, prop_name, data, len);
	if (ret)
	return ret;

	len /= 2;
	m->num_cntr = len;
	for (i = 0; i < len; i++) {
	/* disallow non-configurable counters */
	if (data[i * 2] < EVTYPER_START)
	return -EINVAL;
	m->cntr[i].idx = data[i * 2];
	m->cntr[i].event_mask = data[i * 2 + 1];
	}

	devm_kfree(dev, data);
	return 0;
	}

	static int m4m_hwmon_driver_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct resource *res;
	struct m4m_hwmon *m;
	int ret;

	m = devm_kzalloc(dev, sizeof(*m), GFP_KERNEL);
	if (!m)
	return -ENOMEM;
	m->dev = dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	dev_err(dev, "base not found!\n");
	return -EINVAL;
	}
	m->base = devm_ioremap(dev, res->start, resource_size(res));
	if (!m->base)
	return -ENOMEM;

	m->irq = platform_get_irq(pdev, 0);
	if (m->irq < 0) {
	dev_err(dev, "Unable to get IRQ number\n");
	return m->irq;
	}

	ret = m4m_hwmon_parse_cntr(dev, m);
	if (ret) {
	dev_err(dev, "Unable to parse counter events\n");
	return ret;
	}

	m->hw.of_node = of_parse_phandle(dev->of_node, "qcom,target-dev", 0);
	if (!m->hw.of_node)
	return -EINVAL;
	m->hw.start_hwmon = &m4m_start_hwmon;
	m->hw.stop_hwmon = &m4m_stop_hwmon;
	m->hw.meas_mrps_and_set_irq = &m4m_meas_mrps_and_set_irq;

	ret = register_cache_hwmon(dev, &m->hw);
	if (ret) {
	dev_err(dev, "Dev BW hwmon registration failed\n");
	return ret;
	}

	return 0;
	}

	static struct platform_driver m4m_hwmon_driver = {
	.probe = m4m_hwmon_driver_probe,
	.driver = {
	.name = "m4m-hwmon",
	.of_match_table = m4m_match_table,
	},
	};

	module_platform_driver(m4m_hwmon_driver);
	MODULE_DESCRIPTION("M4M hardware monitor driver");
	MODULE_LICENSE("GPL v2");