drivers/pwm/pwm-atmel.c - kernel/msm.git - Git at Google

 /*
  * Driver for Atmel Pulse Width Modulation Controller
  *
  * Copyright (C) 2013 Atmel Corporation
  *		 Bo Shen <voice.shen@atmel.com>
  *
  * Licensed under GPLv2.
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>

 /* The following is global registers for PWM controller */
 #define PWM_ENA			0x04
 #define PWM_DIS			0x08
 #define PWM_SR			0x0C
 #define PWM_ISR			0x1C
 /* Bit field in SR */
 #define PWM_SR_ALL_CH_ON	0x0F

 /* The following register is PWM channel related registers */
 #define PWM_CH_REG_OFFSET	0x200
 #define PWM_CH_REG_SIZE		0x20

 #define PWM_CMR			0x0
 /* Bit field in CMR */
 #define PWM_CMR_CPOL		(1 << 9)
 #define PWM_CMR_UPD_CDTY	(1 << 10)
 #define PWM_CMR_CPRE_MSK	0xF

 /* The following registers for PWM v1 */
 #define PWMV1_CDTY		0x04
 #define PWMV1_CPRD		0x08
 #define PWMV1_CUPD		0x10

 /* The following registers for PWM v2 */
 #define PWMV2_CDTY		0x04
 #define PWMV2_CDTYUPD		0x08
 #define PWMV2_CPRD		0x0C
 #define PWMV2_CPRDUPD		0x10

 /*
  * Max value for duty and period
  *
  * Although the duty and period register is 32 bit,
  * however only the LSB 16 bits are significant.
  */
 #define PWM_MAX_DTY		0xFFFF
 #define PWM_MAX_PRD		0xFFFF
 #define PRD_MAX_PRES		10

 struct atmel_pwm_chip {
 	struct pwm_chip chip;
 	struct clk *clk;
 	void __iomem *base;

 	unsigned int updated_pwms;
 	struct mutex isr_lock; /* ISR is cleared when read, ensure only one thread does that */

 	void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
 		       unsigned long dty, unsigned long prd);
 };

 static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct atmel_pwm_chip, chip);
 }

 static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip,
 				  unsigned long offset)
 {
 	return readl_relaxed(chip->base + offset);
 }

 static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
 				    unsigned long offset, unsigned long val)
 {
 	writel_relaxed(val, chip->base + offset);
 }

 static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
 				     unsigned int ch, unsigned long offset)
 {
 	unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;

 	return readl_relaxed(chip->base + base + offset);
 }

 static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
 				       unsigned int ch, unsigned long offset,
 				       unsigned long val)
 {
 	unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;

 	writel_relaxed(val, chip->base + base + offset);
 }

 static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			    int duty_ns, int period_ns)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	unsigned long prd, dty;
 	unsigned long long div;
 	unsigned int pres = 0;
 	u32 val;
 	int ret;

 	if (pwm_is_enabled(pwm) && (period_ns != pwm_get_period(pwm))) {
 		dev_err(chip->dev, "cannot change PWM period while enabled\n");
 		return -EBUSY;
 	}

 	/* Calculate the period cycles and prescale value */
 	div = (unsigned long long)clk_get_rate(atmel_pwm->clk) * period_ns;
 	do_div(div, NSEC_PER_SEC);

 	while (div > PWM_MAX_PRD) {
 		div >>= 1;
 		pres++;
 	}

 	if (pres > PRD_MAX_PRES) {
 		dev_err(chip->dev, "pres exceeds the maximum value\n");
 		return -EINVAL;
 	}

 	/* Calculate the duty cycles */
 	prd = div;
 	div *= duty_ns;
 	do_div(div, period_ns);
 	dty = prd - div;

 	ret = clk_enable(atmel_pwm->clk);
 	if (ret) {
 		dev_err(chip->dev, "failed to enable PWM clock\n");
 		return ret;
 	}

 	/* It is necessary to preserve CPOL, inside CMR */
 	val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
 	val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK);
 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
 	atmel_pwm->config(chip, pwm, dty, prd);
 	mutex_lock(&atmel_pwm->isr_lock);
 	atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
 	atmel_pwm->updated_pwms &= ~(1 << pwm->hwpwm);
 	mutex_unlock(&atmel_pwm->isr_lock);

 	clk_disable(atmel_pwm->clk);
 	return ret;
 }

 static void atmel_pwm_config_v1(struct pwm_chip *chip, struct pwm_device *pwm,
 				unsigned long dty, unsigned long prd)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	unsigned int val;


 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CUPD, dty);

 	val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
 	val &= ~PWM_CMR_UPD_CDTY;
 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);

 	/*
 	 * If the PWM channel is enabled, only update CDTY by using the update
 	 * register, it needs to set bit 10 of CMR to 0
 	 */
 	if (pwm_is_enabled(pwm))
 		return;
 	/*
 	 * If the PWM channel is disabled, write value to duty and period
 	 * registers directly.
 	 */
 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CDTY, dty);
 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CPRD, prd);
 }

 static void atmel_pwm_config_v2(struct pwm_chip *chip, struct pwm_device *pwm,
 				unsigned long dty, unsigned long prd)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);

 	if (pwm_is_enabled(pwm)) {
 		/*
 		 * If the PWM channel is enabled, using the duty update register
 		 * to update the value.
 		 */
 		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTYUPD, dty);
 	} else {
 		/*
 		 * If the PWM channel is disabled, write value to duty and
 		 * period registers directly.
 		 */
 		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTY, dty);
 		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CPRD, prd);
 	}
 }

 static int atmel_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 				  enum pwm_polarity polarity)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	u32 val;
 	int ret;

 	val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);

 	if (polarity == PWM_POLARITY_NORMAL)
 		val &= ~PWM_CMR_CPOL;
 	else
 		val |= PWM_CMR_CPOL;

 	ret = clk_enable(atmel_pwm->clk);
 	if (ret) {
 		dev_err(chip->dev, "failed to enable PWM clock\n");
 		return ret;
 	}

 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);

 	clk_disable(atmel_pwm->clk);

 	return 0;
 }

 static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	int ret;

 	ret = clk_enable(atmel_pwm->clk);
 	if (ret) {
 		dev_err(chip->dev, "failed to enable PWM clock\n");
 		return ret;
 	}

 	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);

 	return 0;
 }

 static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	unsigned long timeout = jiffies + 2 * HZ;

 	/*
 	 * Wait for at least a complete period to have passed before disabling a
 	 * channel to be sure that CDTY has been updated
 	 */
 	mutex_lock(&atmel_pwm->isr_lock);
 	atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);

 	while (!(atmel_pwm->updated_pwms & (1 << pwm->hwpwm)) &&
 	       time_before(jiffies, timeout)) {
 		usleep_range(10, 100);
 		atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
 	}

 	mutex_unlock(&atmel_pwm->isr_lock);
 	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);

 	clk_disable(atmel_pwm->clk);
 }

 static const struct pwm_ops atmel_pwm_ops = {
 	.config = atmel_pwm_config,
 	.set_polarity = atmel_pwm_set_polarity,
 	.enable = atmel_pwm_enable,
 	.disable = atmel_pwm_disable,
 	.owner = THIS_MODULE,
 };

 struct atmel_pwm_data {
 	void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
 		       unsigned long dty, unsigned long prd);
 };

 static const struct atmel_pwm_data atmel_pwm_data_v1 = {
 	.config = atmel_pwm_config_v1,
 };

 static const struct atmel_pwm_data atmel_pwm_data_v2 = {
 	.config = atmel_pwm_config_v2,
 };

 static const struct platform_device_id atmel_pwm_devtypes[] = {
 	{
 		.name = "at91sam9rl-pwm",
 		.driver_data = (kernel_ulong_t)&atmel_pwm_data_v1,
 	}, {
 		.name = "sama5d3-pwm",
 		.driver_data = (kernel_ulong_t)&atmel_pwm_data_v2,
 	}, {
 		/* sentinel */
 	},
 };
 MODULE_DEVICE_TABLE(platform, atmel_pwm_devtypes);

 static const struct of_device_id atmel_pwm_dt_ids[] = {
 	{
 		.compatible = "atmel,at91sam9rl-pwm",
 		.data = &atmel_pwm_data_v1,
 	}, {
 		.compatible = "atmel,sama5d3-pwm",
 		.data = &atmel_pwm_data_v2,
 	}, {
 		/* sentinel */
 	},
 };
 MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);

 static inline const struct atmel_pwm_data *
 atmel_pwm_get_driver_data(struct platform_device *pdev)
 {
 	if (pdev->dev.of_node) {
 		const struct of_device_id *match;

 		match = of_match_device(atmel_pwm_dt_ids, &pdev->dev);
 		if (!match)
 			return NULL;

 		return match->data;
 	} else {
 		const struct platform_device_id *id;

 		id = platform_get_device_id(pdev);

 		return (struct atmel_pwm_data *)id->driver_data;
 	}
 }

 static int atmel_pwm_probe(struct platform_device *pdev)
 {
 	const struct atmel_pwm_data *data;
 	struct atmel_pwm_chip *atmel_pwm;
 	struct resource *res;
 	int ret;

 	data = atmel_pwm_get_driver_data(pdev);
 	if (!data)
 		return -ENODEV;

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

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	atmel_pwm->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(atmel_pwm->base))
 		return PTR_ERR(atmel_pwm->base);

 	atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(atmel_pwm->clk))
 		return PTR_ERR(atmel_pwm->clk);

 	ret = clk_prepare(atmel_pwm->clk);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to prepare PWM clock\n");
 		return ret;
 	}

 	atmel_pwm->chip.dev = &pdev->dev;
 	atmel_pwm->chip.ops = &atmel_pwm_ops;

 	if (pdev->dev.of_node) {
 		atmel_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 		atmel_pwm->chip.of_pwm_n_cells = 3;
 	}

 	atmel_pwm->chip.base = -1;
 	atmel_pwm->chip.npwm = 4;
 	atmel_pwm->chip.can_sleep = true;
 	atmel_pwm->config = data->config;
 	atmel_pwm->updated_pwms = 0;
 	mutex_init(&atmel_pwm->isr_lock);

 	ret = pwmchip_add(&atmel_pwm->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret);
 		goto unprepare_clk;
 	}

 	platform_set_drvdata(pdev, atmel_pwm);

 	return ret;

 unprepare_clk:
 	clk_unprepare(atmel_pwm->clk);
 	return ret;
 }

 static int atmel_pwm_remove(struct platform_device *pdev)
 {
 	struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);

 	clk_unprepare(atmel_pwm->clk);
 	mutex_destroy(&atmel_pwm->isr_lock);

 	return pwmchip_remove(&atmel_pwm->chip);
 }

 static struct platform_driver atmel_pwm_driver = {
 	.driver = {
 		.name = "atmel-pwm",
 		.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
 	},
 	.id_table = atmel_pwm_devtypes,
 	.probe = atmel_pwm_probe,
 	.remove = atmel_pwm_remove,
 };
 module_platform_driver(atmel_pwm_driver);

 MODULE_ALIAS("platform:atmel-pwm");
 MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
 MODULE_DESCRIPTION("Atmel PWM driver");
 MODULE_LICENSE("GPL v2");
	/*
	* Driver for Atmel Pulse Width Modulation Controller
	*
	* Copyright (C) 2013 Atmel Corporation
	* Bo Shen <voice.shen@atmel.com>
	*
	* Licensed under GPLv2.
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/pwm.h>
	#include <linux/slab.h>

	/* The following is global registers for PWM controller */
	#define PWM_ENA 0x04
	#define PWM_DIS 0x08
	#define PWM_SR 0x0C
	#define PWM_ISR 0x1C
	/* Bit field in SR */
	#define PWM_SR_ALL_CH_ON 0x0F

	/* The following register is PWM channel related registers */
	#define PWM_CH_REG_OFFSET 0x200
	#define PWM_CH_REG_SIZE 0x20

	#define PWM_CMR 0x0
	/* Bit field in CMR */
	#define PWM_CMR_CPOL (1 << 9)
	#define PWM_CMR_UPD_CDTY (1 << 10)
	#define PWM_CMR_CPRE_MSK 0xF

	/* The following registers for PWM v1 */
	#define PWMV1_CDTY 0x04
	#define PWMV1_CPRD 0x08
	#define PWMV1_CUPD 0x10

	/* The following registers for PWM v2 */
	#define PWMV2_CDTY 0x04
	#define PWMV2_CDTYUPD 0x08
	#define PWMV2_CPRD 0x0C
	#define PWMV2_CPRDUPD 0x10

	/*
	* Max value for duty and period
	*
	* Although the duty and period register is 32 bit,
	* however only the LSB 16 bits are significant.
	*/
	#define PWM_MAX_DTY 0xFFFF
	#define PWM_MAX_PRD 0xFFFF
	#define PRD_MAX_PRES 10

	struct atmel_pwm_chip {
	struct pwm_chip chip;
	struct clk *clk;
	void __iomem *base;

	unsigned int updated_pwms;
	struct mutex isr_lock; /* ISR is cleared when read, ensure only one thread does that */

	void (config)(struct pwm_chip chip, struct pwm_device *pwm,
	unsigned long dty, unsigned long prd);
	};

	static inline struct atmel_pwm_chip to_atmel_pwm_chip(struct pwm_chip chip)
	{
	return container_of(chip, struct atmel_pwm_chip, chip);
	}

	static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip,
	unsigned long offset)
	{
	return readl_relaxed(chip->base + offset);
	}

	static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
	unsigned long offset, unsigned long val)
	{
	writel_relaxed(val, chip->base + offset);
	}

	static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
	unsigned int ch, unsigned long offset)
	{
	unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;

	return readl_relaxed(chip->base + base + offset);
	}

	static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
	unsigned int ch, unsigned long offset,
	unsigned long val)
	{
	unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;

	writel_relaxed(val, chip->base + base + offset);
	}

	static int atmel_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
	int duty_ns, int period_ns)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	unsigned long prd, dty;
	unsigned long long div;
	unsigned int pres = 0;
	u32 val;
	int ret;

	if (pwm_is_enabled(pwm) && (period_ns != pwm_get_period(pwm))) {
	dev_err(chip->dev, "cannot change PWM period while enabled\n");
	return -EBUSY;
	}

	/* Calculate the period cycles and prescale value */
	div = (unsigned long long)clk_get_rate(atmel_pwm->clk) * period_ns;
	do_div(div, NSEC_PER_SEC);

	while (div > PWM_MAX_PRD) {
	div >>= 1;
	pres++;
	}

	if (pres > PRD_MAX_PRES) {
	dev_err(chip->dev, "pres exceeds the maximum value\n");
	return -EINVAL;
	}

	/* Calculate the duty cycles */
	prd = div;
	div *= duty_ns;
	do_div(div, period_ns);
	dty = prd - div;

	ret = clk_enable(atmel_pwm->clk);
	if (ret) {
	dev_err(chip->dev, "failed to enable PWM clock\n");
	return ret;
	}

	/* It is necessary to preserve CPOL, inside CMR */
	val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
	val = (val & ~PWM_CMR_CPRE_MSK) \| (pres & PWM_CMR_CPRE_MSK);
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
	atmel_pwm->config(chip, pwm, dty, prd);
	mutex_lock(&atmel_pwm->isr_lock);
	atmel_pwm->updated_pwms \|= atmel_pwm_readl(atmel_pwm, PWM_ISR);
	atmel_pwm->updated_pwms &= ~(1 << pwm->hwpwm);
	mutex_unlock(&atmel_pwm->isr_lock);

	clk_disable(atmel_pwm->clk);
	return ret;
	}

	static void atmel_pwm_config_v1(struct pwm_chip chip, struct pwm_device pwm,
	unsigned long dty, unsigned long prd)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	unsigned int val;


	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CUPD, dty);

	val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
	val &= ~PWM_CMR_UPD_CDTY;
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);

	/*
	* If the PWM channel is enabled, only update CDTY by using the update
	* register, it needs to set bit 10 of CMR to 0
	*/
	if (pwm_is_enabled(pwm))
	return;
	/*
	* If the PWM channel is disabled, write value to duty and period
	* registers directly.
	*/
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CDTY, dty);
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CPRD, prd);
	}

	static void atmel_pwm_config_v2(struct pwm_chip chip, struct pwm_device pwm,
	unsigned long dty, unsigned long prd)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);

	if (pwm_is_enabled(pwm)) {
	/*
	* If the PWM channel is enabled, using the duty update register
	* to update the value.
	*/
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTYUPD, dty);
	} else {
	/*
	* If the PWM channel is disabled, write value to duty and
	* period registers directly.
	*/
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTY, dty);
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CPRD, prd);
	}
	}

	static int atmel_pwm_set_polarity(struct pwm_chip chip, struct pwm_device pwm,
	enum pwm_polarity polarity)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	u32 val;
	int ret;

	val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);

	if (polarity == PWM_POLARITY_NORMAL)
	val &= ~PWM_CMR_CPOL;
	else
	val \|= PWM_CMR_CPOL;

	ret = clk_enable(atmel_pwm->clk);
	if (ret) {
	dev_err(chip->dev, "failed to enable PWM clock\n");
	return ret;
	}

	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);

	clk_disable(atmel_pwm->clk);

	return 0;
	}

	static int atmel_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	int ret;

	ret = clk_enable(atmel_pwm->clk);
	if (ret) {
	dev_err(chip->dev, "failed to enable PWM clock\n");
	return ret;
	}

	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);

	return 0;
	}

	static void atmel_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	unsigned long timeout = jiffies + 2 * HZ;

	/*
	* Wait for at least a complete period to have passed before disabling a
	* channel to be sure that CDTY has been updated
	*/
	mutex_lock(&atmel_pwm->isr_lock);
	atmel_pwm->updated_pwms \|= atmel_pwm_readl(atmel_pwm, PWM_ISR);

	while (!(atmel_pwm->updated_pwms & (1 << pwm->hwpwm)) &&
	time_before(jiffies, timeout)) {
	usleep_range(10, 100);
	atmel_pwm->updated_pwms \|= atmel_pwm_readl(atmel_pwm, PWM_ISR);
	}

	mutex_unlock(&atmel_pwm->isr_lock);
	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);

	clk_disable(atmel_pwm->clk);
	}

	static const struct pwm_ops atmel_pwm_ops = {
	.config = atmel_pwm_config,
	.set_polarity = atmel_pwm_set_polarity,
	.enable = atmel_pwm_enable,
	.disable = atmel_pwm_disable,
	.owner = THIS_MODULE,
	};

	struct atmel_pwm_data {
	void (config)(struct pwm_chip chip, struct pwm_device *pwm,
	unsigned long dty, unsigned long prd);
	};

	static const struct atmel_pwm_data atmel_pwm_data_v1 = {
	.config = atmel_pwm_config_v1,
	};

	static const struct atmel_pwm_data atmel_pwm_data_v2 = {
	.config = atmel_pwm_config_v2,
	};

	static const struct platform_device_id atmel_pwm_devtypes[] = {
	{
	.name = "at91sam9rl-pwm",
	.driver_data = (kernel_ulong_t)&atmel_pwm_data_v1,
	}, {
	.name = "sama5d3-pwm",
	.driver_data = (kernel_ulong_t)&atmel_pwm_data_v2,
	}, {
	/* sentinel */
	},
	};
	MODULE_DEVICE_TABLE(platform, atmel_pwm_devtypes);

	static const struct of_device_id atmel_pwm_dt_ids[] = {
	{
	.compatible = "atmel,at91sam9rl-pwm",
	.data = &atmel_pwm_data_v1,
	}, {
	.compatible = "atmel,sama5d3-pwm",
	.data = &atmel_pwm_data_v2,
	}, {
	/* sentinel */
	},
	};
	MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);

	static inline const struct atmel_pwm_data *
	atmel_pwm_get_driver_data(struct platform_device *pdev)
	{
	if (pdev->dev.of_node) {
	const struct of_device_id *match;

	match = of_match_device(atmel_pwm_dt_ids, &pdev->dev);
	if (!match)
	return NULL;

	return match->data;
	} else {
	const struct platform_device_id *id;

	id = platform_get_device_id(pdev);

	return (struct atmel_pwm_data *)id->driver_data;
	}
	}

	static int atmel_pwm_probe(struct platform_device *pdev)
	{
	const struct atmel_pwm_data *data;
	struct atmel_pwm_chip *atmel_pwm;
	struct resource *res;
	int ret;

	data = atmel_pwm_get_driver_data(pdev);
	if (!data)
	return -ENODEV;

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

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	atmel_pwm->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(atmel_pwm->base))
	return PTR_ERR(atmel_pwm->base);

	atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(atmel_pwm->clk))
	return PTR_ERR(atmel_pwm->clk);

	ret = clk_prepare(atmel_pwm->clk);
	if (ret) {
	dev_err(&pdev->dev, "failed to prepare PWM clock\n");
	return ret;
	}

	atmel_pwm->chip.dev = &pdev->dev;
	atmel_pwm->chip.ops = &atmel_pwm_ops;

	if (pdev->dev.of_node) {
	atmel_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
	atmel_pwm->chip.of_pwm_n_cells = 3;
	}

	atmel_pwm->chip.base = -1;
	atmel_pwm->chip.npwm = 4;
	atmel_pwm->chip.can_sleep = true;
	atmel_pwm->config = data->config;
	atmel_pwm->updated_pwms = 0;
	mutex_init(&atmel_pwm->isr_lock);

	ret = pwmchip_add(&atmel_pwm->chip);
	if (ret < 0) {
	dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret);
	goto unprepare_clk;
	}

	platform_set_drvdata(pdev, atmel_pwm);

	return ret;

	unprepare_clk:
	clk_unprepare(atmel_pwm->clk);
	return ret;
	}

	static int atmel_pwm_remove(struct platform_device *pdev)
	{
	struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);

	clk_unprepare(atmel_pwm->clk);
	mutex_destroy(&atmel_pwm->isr_lock);

	return pwmchip_remove(&atmel_pwm->chip);
	}

	static struct platform_driver atmel_pwm_driver = {
	.driver = {
	.name = "atmel-pwm",
	.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
	},
	.id_table = atmel_pwm_devtypes,
	.probe = atmel_pwm_probe,
	.remove = atmel_pwm_remove,
	};
	module_platform_driver(atmel_pwm_driver);

	MODULE_ALIAS("platform:atmel-pwm");
	MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
	MODULE_DESCRIPTION("Atmel PWM driver");
	MODULE_LICENSE("GPL v2");