drivers/pwm/pwm-atmel.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Driver for Atmel Pulse Width Modulation Controller
  *
  * Copyright (C) 2013 Atmel Corporation
  *		 Bo Shen <voice.shen@atmel.com>
  *
  * Links to reference manuals for the supported PWM chips can be found in
  * Documentation/arm/microchip.rst.
  *
  * Limitations:
  * - Periods start with the inactive level.
  * - Hardware has to be stopped in general to update settings.
  *
  * Software bugs/possible improvements:
  * - When atmel_pwm_apply() is called with state->enabled=false a change in
  *   state->polarity isn't honored.
  * - Instead of sleeping to wait for a completed period, the interrupt
  *   functionality could be used.
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.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

 #define PWM_MAX_PRES		10

 struct atmel_pwm_registers {
 	u8 period;
 	u8 period_upd;
 	u8 duty;
 	u8 duty_upd;
 };

 struct atmel_pwm_config {
 	u32 period_bits;
 };

 struct atmel_pwm_data {
 	struct atmel_pwm_registers regs;
 	struct atmel_pwm_config cfg;
 };

 struct atmel_pwm_chip {
 	struct pwm_chip chip;
 	struct clk *clk;
 	void __iomem *base;
 	const struct atmel_pwm_data *data;

 	/*
 	 * The hardware supports a mechanism to update a channel's duty cycle at
 	 * the end of the currently running period. When such an update is
 	 * pending we delay disabling the PWM until the new configuration is
 	 * active because otherwise pmw_config(duty_cycle=0); pwm_disable();
 	 * might not result in an inactive output.
 	 * This bitmask tracks for which channels an update is pending in
 	 * hardware.
 	 */
 	u32 update_pending;

 	/* Protects .update_pending */
 	spinlock_t lock;
 };

 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 atmel_pwm_readl(chip, 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;

 	atmel_pwm_writel(chip, base + offset, val);
 }

 static void atmel_pwm_update_pending(struct atmel_pwm_chip *chip)
 {
 	/*
 	 * Each channel that has its bit in ISR set started a new period since
 	 * ISR was cleared and so there is no more update pending.  Note that
 	 * reading ISR clears it, so this needs to handle all channels to not
 	 * loose information.
 	 */
 	u32 isr = atmel_pwm_readl(chip, PWM_ISR);

 	chip->update_pending &= ~isr;
 }

 static void atmel_pwm_set_pending(struct atmel_pwm_chip *chip, unsigned int ch)
 {
 	spin_lock(&chip->lock);

 	/*
 	 * Clear pending flags in hardware because otherwise there might still
 	 * be a stale flag in ISR.
 	 */
 	atmel_pwm_update_pending(chip);

 	chip->update_pending |= (1 << ch);

 	spin_unlock(&chip->lock);
 }

 static int atmel_pwm_test_pending(struct atmel_pwm_chip *chip, unsigned int ch)
 {
 	int ret = 0;

 	spin_lock(&chip->lock);

 	if (chip->update_pending & (1 << ch)) {
 		atmel_pwm_update_pending(chip);

 		if (chip->update_pending & (1 << ch))
 			ret = 1;
 	}

 	spin_unlock(&chip->lock);

 	return ret;
 }

 static int atmel_pwm_wait_nonpending(struct atmel_pwm_chip *chip, unsigned int ch)
 {
 	unsigned long timeout = jiffies + 2 * HZ;
 	int ret;

 	while ((ret = atmel_pwm_test_pending(chip, ch)) &&
 	       time_before(jiffies, timeout))
 		usleep_range(10, 100);

 	return ret ? -ETIMEDOUT : 0;
 }

 static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip,
 					     unsigned long clkrate,
 					     const struct pwm_state *state,
 					     unsigned long *cprd, u32 *pres)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	unsigned long long cycles = state->period;
 	int shift;

 	/* Calculate the period cycles and prescale value */
 	cycles *= clkrate;
 	do_div(cycles, NSEC_PER_SEC);

 	/*
 	 * The register for the period length is cfg.period_bits bits wide.
 	 * So for each bit the number of clock cycles is wider divide the input
 	 * clock frequency by two using pres and shift cprd accordingly.
 	 */
 	shift = fls(cycles) - atmel_pwm->data->cfg.period_bits;

 	if (shift > PWM_MAX_PRES) {
 		dev_err(chip->dev, "pres exceeds the maximum value\n");
 		return -EINVAL;
 	} else if (shift > 0) {
 		*pres = shift;
 		cycles >>= *pres;
 	} else {
 		*pres = 0;
 	}

 	*cprd = cycles;

 	return 0;
 }

 static void atmel_pwm_calculate_cdty(const struct pwm_state *state,
 				     unsigned long clkrate, unsigned long cprd,
 				     u32 pres, unsigned long *cdty)
 {
 	unsigned long long cycles = state->duty_cycle;

 	cycles *= clkrate;
 	do_div(cycles, NSEC_PER_SEC);
 	cycles >>= pres;
 	*cdty = cprd - cycles;
 }

 static void atmel_pwm_update_cdty(struct pwm_chip *chip, struct pwm_device *pwm,
 				  unsigned long cdty)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	u32 val;

 	if (atmel_pwm->data->regs.duty_upd ==
 	    atmel_pwm->data->regs.period_upd) {
 		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);
 	}

 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
 			    atmel_pwm->data->regs.duty_upd, cdty);
 	atmel_pwm_set_pending(atmel_pwm, pwm->hwpwm);
 }

 static void atmel_pwm_set_cprd_cdty(struct pwm_chip *chip,
 				    struct pwm_device *pwm,
 				    unsigned long cprd, unsigned long cdty)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);

 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
 			    atmel_pwm->data->regs.duty, cdty);
 	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
 			    atmel_pwm->data->regs.period, cprd);
 }

 static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm,
 			      bool disable_clk)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	unsigned long timeout;

 	atmel_pwm_wait_nonpending(atmel_pwm, pwm->hwpwm);

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

 	/*
 	 * Wait for the PWM channel disable operation to be effective before
 	 * stopping the clock.
 	 */
 	timeout = jiffies + 2 * HZ;

 	while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) &&
 	       time_before(jiffies, timeout))
 		usleep_range(10, 100);

 	if (disable_clk)
 		clk_disable(atmel_pwm->clk);
 }

 static int atmel_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			   const struct pwm_state *state)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	struct pwm_state cstate;
 	unsigned long cprd, cdty;
 	u32 pres, val;
 	int ret;

 	pwm_get_state(pwm, &cstate);

 	if (state->enabled) {
 		unsigned long clkrate = clk_get_rate(atmel_pwm->clk);

 		if (cstate.enabled &&
 		    cstate.polarity == state->polarity &&
 		    cstate.period == state->period) {
 			u32 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);

 			cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
 						  atmel_pwm->data->regs.period);
 			pres = cmr & PWM_CMR_CPRE_MSK;

 			atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);
 			atmel_pwm_update_cdty(chip, pwm, cdty);
 			return 0;
 		}

 		ret = atmel_pwm_calculate_cprd_and_pres(chip, clkrate, state, &cprd,
 							&pres);
 		if (ret) {
 			dev_err(chip->dev,
 				"failed to calculate cprd and prescaler\n");
 			return ret;
 		}

 		atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);

 		if (cstate.enabled) {
 			atmel_pwm_disable(chip, pwm, false);
 		} else {
 			ret = clk_enable(atmel_pwm->clk);
 			if (ret) {
 				dev_err(chip->dev, "failed to enable 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);
 		if (state->polarity == PWM_POLARITY_NORMAL)
 			val &= ~PWM_CMR_CPOL;
 		else
 			val |= PWM_CMR_CPOL;
 		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
 		atmel_pwm_set_cprd_cdty(chip, pwm, cprd, cdty);
 		atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
 	} else if (cstate.enabled) {
 		atmel_pwm_disable(chip, pwm, true);
 	}

 	return 0;
 }

 static int atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 			       struct pwm_state *state)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	u32 sr, cmr;

 	sr = atmel_pwm_readl(atmel_pwm, PWM_SR);
 	cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);

 	if (sr & (1 << pwm->hwpwm)) {
 		unsigned long rate = clk_get_rate(atmel_pwm->clk);
 		u32 cdty, cprd, pres;
 		u64 tmp;

 		pres = cmr & PWM_CMR_CPRE_MSK;

 		cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
 					  atmel_pwm->data->regs.period);
 		tmp = (u64)cprd * NSEC_PER_SEC;
 		tmp <<= pres;
 		state->period = DIV64_U64_ROUND_UP(tmp, rate);

 		/* Wait for an updated duty_cycle queued in hardware */
 		atmel_pwm_wait_nonpending(atmel_pwm, pwm->hwpwm);

 		cdty = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
 					  atmel_pwm->data->regs.duty);
 		tmp = (u64)(cprd - cdty) * NSEC_PER_SEC;
 		tmp <<= pres;
 		state->duty_cycle = DIV64_U64_ROUND_UP(tmp, rate);

 		state->enabled = true;
 	} else {
 		state->enabled = false;
 	}

 	if (cmr & PWM_CMR_CPOL)
 		state->polarity = PWM_POLARITY_INVERSED;
 	else
 		state->polarity = PWM_POLARITY_NORMAL;

 	return 0;
 }

 static const struct pwm_ops atmel_pwm_ops = {
 	.apply = atmel_pwm_apply,
 	.get_state = atmel_pwm_get_state,
 	.owner = THIS_MODULE,
 };

 static const struct atmel_pwm_data atmel_sam9rl_pwm_data = {
 	.regs = {
 		.period		= PWMV1_CPRD,
 		.period_upd	= PWMV1_CUPD,
 		.duty		= PWMV1_CDTY,
 		.duty_upd	= PWMV1_CUPD,
 	},
 	.cfg = {
 		/* 16 bits to keep period and duty. */
 		.period_bits	= 16,
 	},
 };

 static const struct atmel_pwm_data atmel_sama5_pwm_data = {
 	.regs = {
 		.period		= PWMV2_CPRD,
 		.period_upd	= PWMV2_CPRDUPD,
 		.duty		= PWMV2_CDTY,
 		.duty_upd	= PWMV2_CDTYUPD,
 	},
 	.cfg = {
 		/* 16 bits to keep period and duty. */
 		.period_bits	= 16,
 	},
 };

 static const struct atmel_pwm_data mchp_sam9x60_pwm_data = {
 	.regs = {
 		.period		= PWMV1_CPRD,
 		.period_upd	= PWMV1_CUPD,
 		.duty		= PWMV1_CDTY,
 		.duty_upd	= PWMV1_CUPD,
 	},
 	.cfg = {
 		/* 32 bits to keep period and duty. */
 		.period_bits	= 32,
 	},
 };

 static const struct of_device_id atmel_pwm_dt_ids[] = {
 	{
 		.compatible = "atmel,at91sam9rl-pwm",
 		.data = &atmel_sam9rl_pwm_data,
 	}, {
 		.compatible = "atmel,sama5d3-pwm",
 		.data = &atmel_sama5_pwm_data,
 	}, {
 		.compatible = "atmel,sama5d2-pwm",
 		.data = &atmel_sama5_pwm_data,
 	}, {
 		.compatible = "microchip,sam9x60-pwm",
 		.data = &mchp_sam9x60_pwm_data,
 	}, {
 		/* sentinel */
 	},
 };
 MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);

 static int atmel_pwm_probe(struct platform_device *pdev)
 {
 	struct atmel_pwm_chip *atmel_pwm;
 	int ret;

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

 	atmel_pwm->data = of_device_get_match_data(&pdev->dev);

 	atmel_pwm->update_pending = 0;
 	spin_lock_init(&atmel_pwm->lock);

 	atmel_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 	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;
 	atmel_pwm->chip.npwm = 4;

 	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);

 	pwmchip_remove(&atmel_pwm->chip);

 	clk_unprepare(atmel_pwm->clk);

 	return 0;
 }

 static struct platform_driver atmel_pwm_driver = {
 	.driver = {
 		.name = "atmel-pwm",
 		.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
 	},
 	.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");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Driver for Atmel Pulse Width Modulation Controller
	*
	* Copyright (C) 2013 Atmel Corporation
	* Bo Shen <voice.shen@atmel.com>
	*
	* Links to reference manuals for the supported PWM chips can be found in
	* Documentation/arm/microchip.rst.
	*
	* Limitations:
	* - Periods start with the inactive level.
	* - Hardware has to be stopped in general to update settings.
	*
	* Software bugs/possible improvements:
	* - When atmel_pwm_apply() is called with state->enabled=false a change in
	* state->polarity isn't honored.
	* - Instead of sleeping to wait for a completed period, the interrupt
	* functionality could be used.
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/module.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

	#define PWM_MAX_PRES 10

	struct atmel_pwm_registers {
	u8 period;
	u8 period_upd;
	u8 duty;
	u8 duty_upd;
	};

	struct atmel_pwm_config {
	u32 period_bits;
	};

	struct atmel_pwm_data {
	struct atmel_pwm_registers regs;
	struct atmel_pwm_config cfg;
	};

	struct atmel_pwm_chip {
	struct pwm_chip chip;
	struct clk *clk;
	void __iomem *base;
	const struct atmel_pwm_data *data;

	/*
	* The hardware supports a mechanism to update a channel's duty cycle at
	* the end of the currently running period. When such an update is
	* pending we delay disabling the PWM until the new configuration is
	* active because otherwise pmw_config(duty_cycle=0); pwm_disable();
	* might not result in an inactive output.
	* This bitmask tracks for which channels an update is pending in
	* hardware.
	*/
	u32 update_pending;

	/* Protects .update_pending */
	spinlock_t lock;
	};

	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 atmel_pwm_readl(chip, 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;

	atmel_pwm_writel(chip, base + offset, val);
	}

	static void atmel_pwm_update_pending(struct atmel_pwm_chip *chip)
	{
	/*
	* Each channel that has its bit in ISR set started a new period since
	* ISR was cleared and so there is no more update pending. Note that
	* reading ISR clears it, so this needs to handle all channels to not
	* loose information.
	*/
	u32 isr = atmel_pwm_readl(chip, PWM_ISR);

	chip->update_pending &= ~isr;
	}

	static void atmel_pwm_set_pending(struct atmel_pwm_chip *chip, unsigned int ch)
	{
	spin_lock(&chip->lock);

	/*
	* Clear pending flags in hardware because otherwise there might still
	* be a stale flag in ISR.
	*/
	atmel_pwm_update_pending(chip);

	chip->update_pending \|= (1 << ch);

	spin_unlock(&chip->lock);
	}

	static int atmel_pwm_test_pending(struct atmel_pwm_chip *chip, unsigned int ch)
	{
	int ret = 0;

	spin_lock(&chip->lock);

	if (chip->update_pending & (1 << ch)) {
	atmel_pwm_update_pending(chip);

	if (chip->update_pending & (1 << ch))
	ret = 1;
	}

	spin_unlock(&chip->lock);

	return ret;
	}

	static int atmel_pwm_wait_nonpending(struct atmel_pwm_chip *chip, unsigned int ch)
	{
	unsigned long timeout = jiffies + 2 * HZ;
	int ret;

	while ((ret = atmel_pwm_test_pending(chip, ch)) &&
	time_before(jiffies, timeout))
	usleep_range(10, 100);

	return ret ? -ETIMEDOUT : 0;
	}

	static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip,
	unsigned long clkrate,
	const struct pwm_state *state,
	unsigned long cprd, u32 pres)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	unsigned long long cycles = state->period;
	int shift;

	/* Calculate the period cycles and prescale value */
	cycles *= clkrate;
	do_div(cycles, NSEC_PER_SEC);

	/*
	* The register for the period length is cfg.period_bits bits wide.
	* So for each bit the number of clock cycles is wider divide the input
	* clock frequency by two using pres and shift cprd accordingly.
	*/
	shift = fls(cycles) - atmel_pwm->data->cfg.period_bits;

	if (shift > PWM_MAX_PRES) {
	dev_err(chip->dev, "pres exceeds the maximum value\n");
	return -EINVAL;
	} else if (shift > 0) {
	*pres = shift;
	cycles >>= *pres;
	} else {
	*pres = 0;
	}

	*cprd = cycles;

	return 0;
	}

	static void atmel_pwm_calculate_cdty(const struct pwm_state *state,
	unsigned long clkrate, unsigned long cprd,
	u32 pres, unsigned long *cdty)
	{
	unsigned long long cycles = state->duty_cycle;

	cycles *= clkrate;
	do_div(cycles, NSEC_PER_SEC);
	cycles >>= pres;
	*cdty = cprd - cycles;
	}

	static void atmel_pwm_update_cdty(struct pwm_chip chip, struct pwm_device pwm,
	unsigned long cdty)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	u32 val;

	if (atmel_pwm->data->regs.duty_upd ==
	atmel_pwm->data->regs.period_upd) {
	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);
	}

	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
	atmel_pwm->data->regs.duty_upd, cdty);
	atmel_pwm_set_pending(atmel_pwm, pwm->hwpwm);
	}

	static void atmel_pwm_set_cprd_cdty(struct pwm_chip *chip,
	struct pwm_device *pwm,
	unsigned long cprd, unsigned long cdty)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);

	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
	atmel_pwm->data->regs.duty, cdty);
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
	atmel_pwm->data->regs.period, cprd);
	}

	static void atmel_pwm_disable(struct pwm_chip chip, struct pwm_device pwm,
	bool disable_clk)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	unsigned long timeout;

	atmel_pwm_wait_nonpending(atmel_pwm, pwm->hwpwm);

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

	/*
	* Wait for the PWM channel disable operation to be effective before
	* stopping the clock.
	*/
	timeout = jiffies + 2 * HZ;

	while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) &&
	time_before(jiffies, timeout))
	usleep_range(10, 100);

	if (disable_clk)
	clk_disable(atmel_pwm->clk);
	}

	static int atmel_pwm_apply(struct pwm_chip chip, struct pwm_device pwm,
	const struct pwm_state *state)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	struct pwm_state cstate;
	unsigned long cprd, cdty;
	u32 pres, val;
	int ret;

	pwm_get_state(pwm, &cstate);

	if (state->enabled) {
	unsigned long clkrate = clk_get_rate(atmel_pwm->clk);

	if (cstate.enabled &&
	cstate.polarity == state->polarity &&
	cstate.period == state->period) {
	u32 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);

	cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
	atmel_pwm->data->regs.period);
	pres = cmr & PWM_CMR_CPRE_MSK;

	atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);
	atmel_pwm_update_cdty(chip, pwm, cdty);
	return 0;
	}

	ret = atmel_pwm_calculate_cprd_and_pres(chip, clkrate, state, &cprd,
	&pres);
	if (ret) {
	dev_err(chip->dev,
	"failed to calculate cprd and prescaler\n");
	return ret;
	}

	atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);

	if (cstate.enabled) {
	atmel_pwm_disable(chip, pwm, false);
	} else {
	ret = clk_enable(atmel_pwm->clk);
	if (ret) {
	dev_err(chip->dev, "failed to enable 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);
	if (state->polarity == PWM_POLARITY_NORMAL)
	val &= ~PWM_CMR_CPOL;
	else
	val \|= PWM_CMR_CPOL;
	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
	atmel_pwm_set_cprd_cdty(chip, pwm, cprd, cdty);
	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
	} else if (cstate.enabled) {
	atmel_pwm_disable(chip, pwm, true);
	}

	return 0;
	}

	static int atmel_pwm_get_state(struct pwm_chip chip, struct pwm_device pwm,
	struct pwm_state *state)
	{
	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
	u32 sr, cmr;

	sr = atmel_pwm_readl(atmel_pwm, PWM_SR);
	cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);

	if (sr & (1 << pwm->hwpwm)) {
	unsigned long rate = clk_get_rate(atmel_pwm->clk);
	u32 cdty, cprd, pres;
	u64 tmp;

	pres = cmr & PWM_CMR_CPRE_MSK;

	cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
	atmel_pwm->data->regs.period);
	tmp = (u64)cprd * NSEC_PER_SEC;
	tmp <<= pres;
	state->period = DIV64_U64_ROUND_UP(tmp, rate);

	/* Wait for an updated duty_cycle queued in hardware */
	atmel_pwm_wait_nonpending(atmel_pwm, pwm->hwpwm);

	cdty = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
	atmel_pwm->data->regs.duty);
	tmp = (u64)(cprd - cdty) * NSEC_PER_SEC;
	tmp <<= pres;
	state->duty_cycle = DIV64_U64_ROUND_UP(tmp, rate);

	state->enabled = true;
	} else {
	state->enabled = false;
	}

	if (cmr & PWM_CMR_CPOL)
	state->polarity = PWM_POLARITY_INVERSED;
	else
	state->polarity = PWM_POLARITY_NORMAL;

	return 0;
	}

	static const struct pwm_ops atmel_pwm_ops = {
	.apply = atmel_pwm_apply,
	.get_state = atmel_pwm_get_state,
	.owner = THIS_MODULE,
	};

	static const struct atmel_pwm_data atmel_sam9rl_pwm_data = {
	.regs = {
	.period = PWMV1_CPRD,
	.period_upd = PWMV1_CUPD,
	.duty = PWMV1_CDTY,
	.duty_upd = PWMV1_CUPD,
	},
	.cfg = {
	/* 16 bits to keep period and duty. */
	.period_bits = 16,
	},
	};

	static const struct atmel_pwm_data atmel_sama5_pwm_data = {
	.regs = {
	.period = PWMV2_CPRD,
	.period_upd = PWMV2_CPRDUPD,
	.duty = PWMV2_CDTY,
	.duty_upd = PWMV2_CDTYUPD,
	},
	.cfg = {
	/* 16 bits to keep period and duty. */
	.period_bits = 16,
	},
	};

	static const struct atmel_pwm_data mchp_sam9x60_pwm_data = {
	.regs = {
	.period = PWMV1_CPRD,
	.period_upd = PWMV1_CUPD,
	.duty = PWMV1_CDTY,
	.duty_upd = PWMV1_CUPD,
	},
	.cfg = {
	/* 32 bits to keep period and duty. */
	.period_bits = 32,
	},
	};

	static const struct of_device_id atmel_pwm_dt_ids[] = {
	{
	.compatible = "atmel,at91sam9rl-pwm",
	.data = &atmel_sam9rl_pwm_data,
	}, {
	.compatible = "atmel,sama5d3-pwm",
	.data = &atmel_sama5_pwm_data,
	}, {
	.compatible = "atmel,sama5d2-pwm",
	.data = &atmel_sama5_pwm_data,
	}, {
	.compatible = "microchip,sam9x60-pwm",
	.data = &mchp_sam9x60_pwm_data,
	}, {
	/* sentinel */
	},
	};
	MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);

	static int atmel_pwm_probe(struct platform_device *pdev)
	{
	struct atmel_pwm_chip *atmel_pwm;
	int ret;

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

	atmel_pwm->data = of_device_get_match_data(&pdev->dev);

	atmel_pwm->update_pending = 0;
	spin_lock_init(&atmel_pwm->lock);

	atmel_pwm->base = devm_platform_ioremap_resource(pdev, 0);
	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;
	atmel_pwm->chip.npwm = 4;

	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);

	pwmchip_remove(&atmel_pwm->chip);

	clk_unprepare(atmel_pwm->clk);

	return 0;
	}

	static struct platform_driver atmel_pwm_driver = {
	.driver = {
	.name = "atmel-pwm",
	.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
	},
	.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");