drivers/pwm/pwm-sun4i.c - arm/linux - Git at Google

 /*
  * Driver for Allwinner sun4i Pulse Width Modulation Controller
  *
  * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com>
  *
  * Licensed under GPLv2.
  */

 #include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/jiffies.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>
 #include <linux/spinlock.h>
 #include <linux/time.h>

 #define PWM_CTRL_REG		0x0

 #define PWM_CH_PRD_BASE		0x4
 #define PWM_CH_PRD_OFFSET	0x4
 #define PWM_CH_PRD(ch)		(PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch))

 #define PWMCH_OFFSET		15
 #define PWM_PRESCAL_MASK	GENMASK(3, 0)
 #define PWM_PRESCAL_OFF		0
 #define PWM_EN			BIT(4)
 #define PWM_ACT_STATE		BIT(5)
 #define PWM_CLK_GATING		BIT(6)
 #define PWM_MODE		BIT(7)
 #define PWM_PULSE		BIT(8)
 #define PWM_BYPASS		BIT(9)

 #define PWM_RDY_BASE		28
 #define PWM_RDY_OFFSET		1
 #define PWM_RDY(ch)		BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch))

 #define PWM_PRD(prd)		(((prd) - 1) << 16)
 #define PWM_PRD_MASK		GENMASK(15, 0)

 #define PWM_DTY_MASK		GENMASK(15, 0)

 #define PWM_REG_PRD(reg)	((((reg) >> 16) & PWM_PRD_MASK) + 1)
 #define PWM_REG_DTY(reg)	((reg) & PWM_DTY_MASK)
 #define PWM_REG_PRESCAL(reg, chan)	(((reg) >> ((chan) * PWMCH_OFFSET)) & PWM_PRESCAL_MASK)

 #define BIT_CH(bit, chan)	((bit) << ((chan) * PWMCH_OFFSET))

 static const u32 prescaler_table[] = {
 	120,
 	180,
 	240,
 	360,
 	480,
 	0,
 	0,
 	0,
 	12000,
 	24000,
 	36000,
 	48000,
 	72000,
 	0,
 	0,
 	0, /* Actually 1 but tested separately */
 };

 struct sun4i_pwm_data {
 	bool has_prescaler_bypass;
 	bool has_rdy;
 	unsigned int npwm;
 };

 struct sun4i_pwm_chip {
 	struct pwm_chip chip;
 	struct clk *clk;
 	void __iomem *base;
 	spinlock_t ctrl_lock;
 	const struct sun4i_pwm_data *data;
 	unsigned long next_period[2];
 	bool needs_delay[2];
 };

 static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct sun4i_pwm_chip, chip);
 }

 static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
 				  unsigned long offset)
 {
 	return readl(chip->base + offset);
 }

 static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
 				    u32 val, unsigned long offset)
 {
 	writel(val, chip->base + offset);
 }

 static void sun4i_pwm_get_state(struct pwm_chip *chip,
 				struct pwm_device *pwm,
 				struct pwm_state *state)
 {
 	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 	u64 clk_rate, tmp;
 	u32 val;
 	unsigned int prescaler;

 	clk_rate = clk_get_rate(sun4i_pwm->clk);

 	val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);

 	if ((val == PWM_PRESCAL_MASK) && sun4i_pwm->data->has_prescaler_bypass)
 		prescaler = 1;
 	else
 		prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];

 	if (prescaler == 0)
 		return;

 	if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
 		state->polarity = PWM_POLARITY_NORMAL;
 	else
 		state->polarity = PWM_POLARITY_INVERSED;

 	if (val & BIT_CH(PWM_CLK_GATING | PWM_EN, pwm->hwpwm))
 		state->enabled = true;
 	else
 		state->enabled = false;

 	val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm));

 	tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val);
 	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);

 	tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val);
 	state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
 }

 static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
 			       struct pwm_state *state,
 			       u32 *dty, u32 *prd, unsigned int *prsclr)
 {
 	u64 clk_rate, div = 0;
 	unsigned int pval, prescaler = 0;

 	clk_rate = clk_get_rate(sun4i_pwm->clk);

 	if (sun4i_pwm->data->has_prescaler_bypass) {
 		/* First, test without any prescaler when available */
 		prescaler = PWM_PRESCAL_MASK;
 		pval = 1;
 		/*
 		 * When not using any prescaler, the clock period in nanoseconds
 		 * is not an integer so round it half up instead of
 		 * truncating to get less surprising values.
 		 */
 		div = clk_rate * state->period + NSEC_PER_SEC / 2;
 		do_div(div, NSEC_PER_SEC);
 		if (div - 1 > PWM_PRD_MASK)
 			prescaler = 0;
 	}

 	if (prescaler == 0) {
 		/* Go up from the first divider */
 		for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) {
 			if (!prescaler_table[prescaler])
 				continue;
 			pval = prescaler_table[prescaler];
 			div = clk_rate;
 			do_div(div, pval);
 			div = div * state->period;
 			do_div(div, NSEC_PER_SEC);
 			if (div - 1 <= PWM_PRD_MASK)
 				break;
 		}

 		if (div - 1 > PWM_PRD_MASK)
 			return -EINVAL;
 	}

 	*prd = div;
 	div *= state->duty_cycle;
 	do_div(div, state->period);
 	*dty = div;
 	*prsclr = prescaler;

 	div = (u64)pval * NSEC_PER_SEC * *prd;
 	state->period = DIV_ROUND_CLOSEST_ULL(div, clk_rate);

 	div = (u64)pval * NSEC_PER_SEC * *dty;
 	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(div, clk_rate);

 	return 0;
 }

 static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			   struct pwm_state *state)
 {
 	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 	struct pwm_state cstate;
 	u32 ctrl;
 	int ret;
 	unsigned int delay_us;
 	unsigned long now;

 	pwm_get_state(pwm, &cstate);

 	if (!cstate.enabled) {
 		ret = clk_prepare_enable(sun4i_pwm->clk);
 		if (ret) {
 			dev_err(chip->dev, "failed to enable PWM clock\n");
 			return ret;
 		}
 	}

 	spin_lock(&sun4i_pwm->ctrl_lock);
 	ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);

 	if ((cstate.period != state->period) ||
 	    (cstate.duty_cycle != state->duty_cycle)) {
 		u32 period, duty, val;
 		unsigned int prescaler;

 		ret = sun4i_pwm_calculate(sun4i_pwm, state,
 					  &duty, &period, &prescaler);
 		if (ret) {
 			dev_err(chip->dev, "period exceeds the maximum value\n");
 			spin_unlock(&sun4i_pwm->ctrl_lock);
 			if (!cstate.enabled)
 				clk_disable_unprepare(sun4i_pwm->clk);
 			return ret;
 		}

 		if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) {
 			/* Prescaler changed, the clock has to be gated */
 			ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 			sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);

 			ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
 			ctrl |= BIT_CH(prescaler, pwm->hwpwm);
 		}

 		val = (duty & PWM_DTY_MASK) | PWM_PRD(period);
 		sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
 		sun4i_pwm->next_period[pwm->hwpwm] = jiffies +
 			usecs_to_jiffies(cstate.period / 1000 + 1);
 		sun4i_pwm->needs_delay[pwm->hwpwm] = true;
 	}

 	if (state->polarity != PWM_POLARITY_NORMAL)
 		ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
 	else
 		ctrl |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm);

 	ctrl |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 	if (state->enabled) {
 		ctrl |= BIT_CH(PWM_EN, pwm->hwpwm);
 	} else if (!sun4i_pwm->needs_delay[pwm->hwpwm]) {
 		ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm);
 		ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 	}

 	sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);

 	spin_unlock(&sun4i_pwm->ctrl_lock);

 	if (state->enabled)
 		return 0;

 	if (!sun4i_pwm->needs_delay[pwm->hwpwm]) {
 		clk_disable_unprepare(sun4i_pwm->clk);
 		return 0;
 	}

 	/* We need a full period to elapse before disabling the channel. */
 	now = jiffies;
 	if (sun4i_pwm->needs_delay[pwm->hwpwm] &&
 	    time_before(now, sun4i_pwm->next_period[pwm->hwpwm])) {
 		delay_us = jiffies_to_usecs(sun4i_pwm->next_period[pwm->hwpwm] -
 					   now);
 		if ((delay_us / 500) > MAX_UDELAY_MS)
 			msleep(delay_us / 1000 + 1);
 		else
 			usleep_range(delay_us, delay_us * 2);
 	}
 	sun4i_pwm->needs_delay[pwm->hwpwm] = false;

 	spin_lock(&sun4i_pwm->ctrl_lock);
 	ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 	ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 	ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm);
 	sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);
 	spin_unlock(&sun4i_pwm->ctrl_lock);

 	clk_disable_unprepare(sun4i_pwm->clk);

 	return 0;
 }

 static const struct pwm_ops sun4i_pwm_ops = {
 	.apply = sun4i_pwm_apply,
 	.get_state = sun4i_pwm_get_state,
 	.owner = THIS_MODULE,
 };

 static const struct sun4i_pwm_data sun4i_pwm_data_a10 = {
 	.has_prescaler_bypass = false,
 	.has_rdy = false,
 	.npwm = 2,
 };

 static const struct sun4i_pwm_data sun4i_pwm_data_a10s = {
 	.has_prescaler_bypass = true,
 	.has_rdy = true,
 	.npwm = 2,
 };

 static const struct sun4i_pwm_data sun4i_pwm_data_a13 = {
 	.has_prescaler_bypass = true,
 	.has_rdy = true,
 	.npwm = 1,
 };

 static const struct sun4i_pwm_data sun4i_pwm_data_a20 = {
 	.has_prescaler_bypass = true,
 	.has_rdy = true,
 	.npwm = 2,
 };

 static const struct sun4i_pwm_data sun4i_pwm_data_h3 = {
 	.has_prescaler_bypass = true,
 	.has_rdy = true,
 	.npwm = 1,
 };

 static const struct of_device_id sun4i_pwm_dt_ids[] = {
 	{
 		.compatible = "allwinner,sun4i-a10-pwm",
 		.data = &sun4i_pwm_data_a10,
 	}, {
 		.compatible = "allwinner,sun5i-a10s-pwm",
 		.data = &sun4i_pwm_data_a10s,
 	}, {
 		.compatible = "allwinner,sun5i-a13-pwm",
 		.data = &sun4i_pwm_data_a13,
 	}, {
 		.compatible = "allwinner,sun7i-a20-pwm",
 		.data = &sun4i_pwm_data_a20,
 	}, {
 		.compatible = "allwinner,sun8i-h3-pwm",
 		.data = &sun4i_pwm_data_h3,
 	}, {
 		/* sentinel */
 	},
 };
 MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids);

 static int sun4i_pwm_probe(struct platform_device *pdev)
 {
 	struct sun4i_pwm_chip *pwm;
 	struct resource *res;
 	int ret;
 	const struct of_device_id *match;

 	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);

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

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

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

 	pwm->data = match->data;
 	pwm->chip.dev = &pdev->dev;
 	pwm->chip.ops = &sun4i_pwm_ops;
 	pwm->chip.base = -1;
 	pwm->chip.npwm = pwm->data->npwm;
 	pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 	pwm->chip.of_pwm_n_cells = 3;

 	spin_lock_init(&pwm->ctrl_lock);

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

 	platform_set_drvdata(pdev, pwm);

 	return 0;
 }

 static int sun4i_pwm_remove(struct platform_device *pdev)
 {
 	struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);

 	return pwmchip_remove(&pwm->chip);
 }

 static struct platform_driver sun4i_pwm_driver = {
 	.driver = {
 		.name = "sun4i-pwm",
 		.of_match_table = sun4i_pwm_dt_ids,
 	},
 	.probe = sun4i_pwm_probe,
 	.remove = sun4i_pwm_remove,
 };
 module_platform_driver(sun4i_pwm_driver);

 MODULE_ALIAS("platform:sun4i-pwm");
 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
 MODULE_DESCRIPTION("Allwinner sun4i PWM driver");
 MODULE_LICENSE("GPL v2");
	/*
	* Driver for Allwinner sun4i Pulse Width Modulation Controller
	*
	* Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com>
	*
	* Licensed under GPLv2.
	*/

	#include <linux/bitops.h>
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/jiffies.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>
	#include <linux/spinlock.h>
	#include <linux/time.h>

	#define PWM_CTRL_REG 0x0

	#define PWM_CH_PRD_BASE 0x4
	#define PWM_CH_PRD_OFFSET 0x4
	#define PWM_CH_PRD(ch) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch))

	#define PWMCH_OFFSET 15
	#define PWM_PRESCAL_MASK GENMASK(3, 0)
	#define PWM_PRESCAL_OFF 0
	#define PWM_EN BIT(4)
	#define PWM_ACT_STATE BIT(5)
	#define PWM_CLK_GATING BIT(6)
	#define PWM_MODE BIT(7)
	#define PWM_PULSE BIT(8)
	#define PWM_BYPASS BIT(9)

	#define PWM_RDY_BASE 28
	#define PWM_RDY_OFFSET 1
	#define PWM_RDY(ch) BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch))

	#define PWM_PRD(prd) (((prd) - 1) << 16)
	#define PWM_PRD_MASK GENMASK(15, 0)

	#define PWM_DTY_MASK GENMASK(15, 0)

	#define PWM_REG_PRD(reg) ((((reg) >> 16) & PWM_PRD_MASK) + 1)
	#define PWM_REG_DTY(reg) ((reg) & PWM_DTY_MASK)
	#define PWM_REG_PRESCAL(reg, chan) (((reg) >> ((chan) * PWMCH_OFFSET)) & PWM_PRESCAL_MASK)

	#define BIT_CH(bit, chan) ((bit) << ((chan) * PWMCH_OFFSET))

	static const u32 prescaler_table[] = {
	120,
	180,
	240,
	360,
	480,
	0,
	0,
	0,
	12000,
	24000,
	36000,
	48000,
	72000,
	0,
	0,
	0, /* Actually 1 but tested separately */
	};

	struct sun4i_pwm_data {
	bool has_prescaler_bypass;
	bool has_rdy;
	unsigned int npwm;
	};

	struct sun4i_pwm_chip {
	struct pwm_chip chip;
	struct clk *clk;
	void __iomem *base;
	spinlock_t ctrl_lock;
	const struct sun4i_pwm_data *data;
	unsigned long next_period[2];
	bool needs_delay[2];
	};

	static inline struct sun4i_pwm_chip to_sun4i_pwm_chip(struct pwm_chip chip)
	{
	return container_of(chip, struct sun4i_pwm_chip, chip);
	}

	static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
	unsigned long offset)
	{
	return readl(chip->base + offset);
	}

	static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
	u32 val, unsigned long offset)
	{
	writel(val, chip->base + offset);
	}

	static void sun4i_pwm_get_state(struct pwm_chip *chip,
	struct pwm_device *pwm,
	struct pwm_state *state)
	{
	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
	u64 clk_rate, tmp;
	u32 val;
	unsigned int prescaler;

	clk_rate = clk_get_rate(sun4i_pwm->clk);

	val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);

	if ((val == PWM_PRESCAL_MASK) && sun4i_pwm->data->has_prescaler_bypass)
	prescaler = 1;
	else
	prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];

	if (prescaler == 0)
	return;

	if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
	state->polarity = PWM_POLARITY_NORMAL;
	else
	state->polarity = PWM_POLARITY_INVERSED;

	if (val & BIT_CH(PWM_CLK_GATING \| PWM_EN, pwm->hwpwm))
	state->enabled = true;
	else
	state->enabled = false;

	val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm));

	tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val);
	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);

	tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val);
	state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
	}

	static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
	struct pwm_state *state,
	u32 dty, u32 prd, unsigned int *prsclr)
	{
	u64 clk_rate, div = 0;
	unsigned int pval, prescaler = 0;

	clk_rate = clk_get_rate(sun4i_pwm->clk);

	if (sun4i_pwm->data->has_prescaler_bypass) {
	/* First, test without any prescaler when available */
	prescaler = PWM_PRESCAL_MASK;
	pval = 1;
	/*
	* When not using any prescaler, the clock period in nanoseconds
	* is not an integer so round it half up instead of
	* truncating to get less surprising values.
	*/
	div = clk_rate * state->period + NSEC_PER_SEC / 2;
	do_div(div, NSEC_PER_SEC);
	if (div - 1 > PWM_PRD_MASK)
	prescaler = 0;
	}

	if (prescaler == 0) {
	/* Go up from the first divider */
	for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) {
	if (!prescaler_table[prescaler])
	continue;
	pval = prescaler_table[prescaler];
	div = clk_rate;
	do_div(div, pval);
	div = div * state->period;
	do_div(div, NSEC_PER_SEC);
	if (div - 1 <= PWM_PRD_MASK)
	break;
	}

	if (div - 1 > PWM_PRD_MASK)
	return -EINVAL;
	}

	*prd = div;
	div *= state->duty_cycle;
	do_div(div, state->period);
	*dty = div;
	*prsclr = prescaler;

	div = (u64)pval * NSEC_PER_SEC * *prd;
	state->period = DIV_ROUND_CLOSEST_ULL(div, clk_rate);

	div = (u64)pval * NSEC_PER_SEC * *dty;
	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(div, clk_rate);

	return 0;
	}

	static int sun4i_pwm_apply(struct pwm_chip chip, struct pwm_device pwm,
	struct pwm_state *state)
	{
	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
	struct pwm_state cstate;
	u32 ctrl;
	int ret;
	unsigned int delay_us;
	unsigned long now;

	pwm_get_state(pwm, &cstate);

	if (!cstate.enabled) {
	ret = clk_prepare_enable(sun4i_pwm->clk);
	if (ret) {
	dev_err(chip->dev, "failed to enable PWM clock\n");
	return ret;
	}
	}

	spin_lock(&sun4i_pwm->ctrl_lock);
	ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);

	if ((cstate.period != state->period) \|\|
	(cstate.duty_cycle != state->duty_cycle)) {
	u32 period, duty, val;
	unsigned int prescaler;

	ret = sun4i_pwm_calculate(sun4i_pwm, state,
	&duty, &period, &prescaler);
	if (ret) {
	dev_err(chip->dev, "period exceeds the maximum value\n");
	spin_unlock(&sun4i_pwm->ctrl_lock);
	if (!cstate.enabled)
	clk_disable_unprepare(sun4i_pwm->clk);
	return ret;
	}

	if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) {
	/* Prescaler changed, the clock has to be gated */
	ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
	sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);

	ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
	ctrl \|= BIT_CH(prescaler, pwm->hwpwm);
	}

	val = (duty & PWM_DTY_MASK) \| PWM_PRD(period);
	sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
	sun4i_pwm->next_period[pwm->hwpwm] = jiffies +
	usecs_to_jiffies(cstate.period / 1000 + 1);
	sun4i_pwm->needs_delay[pwm->hwpwm] = true;
	}

	if (state->polarity != PWM_POLARITY_NORMAL)
	ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
	else
	ctrl \|= BIT_CH(PWM_ACT_STATE, pwm->hwpwm);

	ctrl \|= BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
	if (state->enabled) {
	ctrl \|= BIT_CH(PWM_EN, pwm->hwpwm);
	} else if (!sun4i_pwm->needs_delay[pwm->hwpwm]) {
	ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm);
	ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
	}

	sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);

	spin_unlock(&sun4i_pwm->ctrl_lock);

	if (state->enabled)
	return 0;

	if (!sun4i_pwm->needs_delay[pwm->hwpwm]) {
	clk_disable_unprepare(sun4i_pwm->clk);
	return 0;
	}

	/* We need a full period to elapse before disabling the channel. */
	now = jiffies;
	if (sun4i_pwm->needs_delay[pwm->hwpwm] &&
	time_before(now, sun4i_pwm->next_period[pwm->hwpwm])) {
	delay_us = jiffies_to_usecs(sun4i_pwm->next_period[pwm->hwpwm] -
	now);
	if ((delay_us / 500) > MAX_UDELAY_MS)
	msleep(delay_us / 1000 + 1);
	else
	usleep_range(delay_us, delay_us * 2);
	}
	sun4i_pwm->needs_delay[pwm->hwpwm] = false;

	spin_lock(&sun4i_pwm->ctrl_lock);
	ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
	ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
	ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm);
	sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);
	spin_unlock(&sun4i_pwm->ctrl_lock);

	clk_disable_unprepare(sun4i_pwm->clk);

	return 0;
	}

	static const struct pwm_ops sun4i_pwm_ops = {
	.apply = sun4i_pwm_apply,
	.get_state = sun4i_pwm_get_state,
	.owner = THIS_MODULE,
	};

	static const struct sun4i_pwm_data sun4i_pwm_data_a10 = {
	.has_prescaler_bypass = false,
	.has_rdy = false,
	.npwm = 2,
	};

	static const struct sun4i_pwm_data sun4i_pwm_data_a10s = {
	.has_prescaler_bypass = true,
	.has_rdy = true,
	.npwm = 2,
	};

	static const struct sun4i_pwm_data sun4i_pwm_data_a13 = {
	.has_prescaler_bypass = true,
	.has_rdy = true,
	.npwm = 1,
	};

	static const struct sun4i_pwm_data sun4i_pwm_data_a20 = {
	.has_prescaler_bypass = true,
	.has_rdy = true,
	.npwm = 2,
	};

	static const struct sun4i_pwm_data sun4i_pwm_data_h3 = {
	.has_prescaler_bypass = true,
	.has_rdy = true,
	.npwm = 1,
	};

	static const struct of_device_id sun4i_pwm_dt_ids[] = {
	{
	.compatible = "allwinner,sun4i-a10-pwm",
	.data = &sun4i_pwm_data_a10,
	}, {
	.compatible = "allwinner,sun5i-a10s-pwm",
	.data = &sun4i_pwm_data_a10s,
	}, {
	.compatible = "allwinner,sun5i-a13-pwm",
	.data = &sun4i_pwm_data_a13,
	}, {
	.compatible = "allwinner,sun7i-a20-pwm",
	.data = &sun4i_pwm_data_a20,
	}, {
	.compatible = "allwinner,sun8i-h3-pwm",
	.data = &sun4i_pwm_data_h3,
	}, {
	/* sentinel */
	},
	};
	MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids);

	static int sun4i_pwm_probe(struct platform_device *pdev)
	{
	struct sun4i_pwm_chip *pwm;
	struct resource *res;
	int ret;
	const struct of_device_id *match;

	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);

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

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

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

	pwm->data = match->data;
	pwm->chip.dev = &pdev->dev;
	pwm->chip.ops = &sun4i_pwm_ops;
	pwm->chip.base = -1;
	pwm->chip.npwm = pwm->data->npwm;
	pwm->chip.of_xlate = of_pwm_xlate_with_flags;
	pwm->chip.of_pwm_n_cells = 3;

	spin_lock_init(&pwm->ctrl_lock);

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

	platform_set_drvdata(pdev, pwm);

	return 0;
	}

	static int sun4i_pwm_remove(struct platform_device *pdev)
	{
	struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);

	return pwmchip_remove(&pwm->chip);
	}

	static struct platform_driver sun4i_pwm_driver = {
	.driver = {
	.name = "sun4i-pwm",
	.of_match_table = sun4i_pwm_dt_ids,
	},
	.probe = sun4i_pwm_probe,
	.remove = sun4i_pwm_remove,
	};
	module_platform_driver(sun4i_pwm_driver);

	MODULE_ALIAS("platform:sun4i-pwm");
	MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
	MODULE_DESCRIPTION("Allwinner sun4i PWM driver");
	MODULE_LICENSE("GPL v2");