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

 /*
  * PWM device driver for ST SoCs.
  * Author: Ajit Pal Singh <ajitpal.singh@st.com>
  *
  * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  */

 #include <linux/clk.h>
 #include <linux/math64.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/time.h>

 #define STI_DS_REG(ch)	(4 * (ch))	/* Channel's Duty Cycle register */
 #define STI_PWMCR	0x50		/* Control/Config register */
 #define STI_INTEN	0x54		/* Interrupt Enable/Disable register */
 #define PWM_PRESCALE_LOW_MASK		0x0f
 #define PWM_PRESCALE_HIGH_MASK		0xf0

 /* Regfield IDs */
 enum {
 	PWMCLK_PRESCALE_LOW,
 	PWMCLK_PRESCALE_HIGH,
 	PWM_EN,
 	PWM_INT_EN,

 	/* Keep last */
 	MAX_REGFIELDS
 };

 struct sti_pwm_compat_data {
 	const struct reg_field *reg_fields;
 	unsigned int num_chan;
 	unsigned int max_pwm_cnt;
 	unsigned int max_prescale;
 };

 struct sti_pwm_chip {
 	struct device *dev;
 	struct clk *clk;
 	unsigned long clk_rate;
 	struct regmap *regmap;
 	struct sti_pwm_compat_data *cdata;
 	struct regmap_field *prescale_low;
 	struct regmap_field *prescale_high;
 	struct regmap_field *pwm_en;
 	struct regmap_field *pwm_int_en;
 	struct pwm_chip chip;
 	struct pwm_device *cur;
 	unsigned int en_count;
 	struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
 	void __iomem *mmio;
 };

 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
 	[PWMCLK_PRESCALE_LOW]	= REG_FIELD(STI_PWMCR, 0, 3),
 	[PWMCLK_PRESCALE_HIGH]	= REG_FIELD(STI_PWMCR, 11, 14),
 	[PWM_EN]		= REG_FIELD(STI_PWMCR, 9, 9),
 	[PWM_INT_EN]		= REG_FIELD(STI_INTEN, 0, 0),
 };

 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct sti_pwm_chip, chip);
 }

 /*
  * Calculate the prescaler value corresponding to the period.
  */
 static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
 				unsigned int *prescale)
 {
 	struct sti_pwm_compat_data *cdata = pc->cdata;
 	unsigned long val;
 	unsigned int ps;

 	/*
 	 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
 	 */
 	val = NSEC_PER_SEC / pc->clk_rate;
 	val *= cdata->max_pwm_cnt + 1;

 	if (period % val) {
 		return -EINVAL;
 	} else {
 		ps  = period / val - 1;
 		if (ps > cdata->max_prescale)
 			return -EINVAL;
 	}
 	*prescale = ps;

 	return 0;
 }

 /* Calculate the number of PWM devices configured with a period. */
 static unsigned int sti_pwm_count_configured(struct pwm_chip *chip)
 {
 	struct pwm_device *pwm;
 	unsigned int ncfg = 0;
 	unsigned int i;

 	for (i = 0; i < chip->npwm; i++) {
 		pwm = &chip->pwms[i];
 		if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
 			if (pwm_get_period(pwm))
 				ncfg++;
 		}
 	}

 	return ncfg;
 }

 /*
  * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
  * The only way to change the period (apart from changing the PWM input clock)
  * is to change the PWM clock prescaler.
  * The prescaler is of 8 bits, so 256 prescaler values and hence
  * 256 possible period values are supported (for a particular clock rate).
  * The requested period will be applied only if it matches one of these
  * 256 values.
  */
 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			 int duty_ns, int period_ns)
 {
 	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 	struct sti_pwm_compat_data *cdata = pc->cdata;
 	struct pwm_device *cur = pc->cur;
 	struct device *dev = pc->dev;
 	unsigned int prescale = 0, pwmvalx;
 	int ret;
 	unsigned int ncfg;
 	bool period_same = false;

 	ncfg = sti_pwm_count_configured(chip);
 	if (ncfg)
 		period_same = (period_ns == pwm_get_period(cur));

 	/* Allow configuration changes if one of the
 	 * following conditions satisfy.
 	 * 1. No channels have been configured.
 	 * 2. Only one channel has been configured and the new request
 	 *    is for the same channel.
 	 * 3. Only one channel has been configured and the new request is
 	 *    for a new channel and period of the new channel is same as
 	 *    the current configured period.
 	 * 4. More than one channels are configured and period of the new
 	 *    requestis the same as the current period.
 	 */
 	if (!ncfg ||
 	    ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
 	    ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
 	    ((ncfg > 1) && period_same)) {
 		/* Enable clock before writing to PWM registers. */
 		ret = clk_enable(pc->clk);
 		if (ret)
 			return ret;

 		if (!period_same) {
 			ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
 			if (ret)
 				goto clk_dis;

 			ret =
 			regmap_field_write(pc->prescale_low,
 					   prescale & PWM_PRESCALE_LOW_MASK);
 			if (ret)
 				goto clk_dis;

 			ret =
 			regmap_field_write(pc->prescale_high,
 				(prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
 			if (ret)
 				goto clk_dis;
 		}

 		/*
 		 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
 		 * When PWMVal == max_pwm_count,
 		 * PWM pulse = (max_pwm_count + 1) local cycles,
 		 * that is continuous pulse: signal never goes low.
 		 */
 		pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;

 		ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
 		if (ret)
 			goto clk_dis;

 		ret = regmap_field_write(pc->pwm_int_en, 0);

 		pc->cur = pwm;

 		dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
 			prescale, period_ns, duty_ns, pwmvalx);
 	} else {
 		return -EINVAL;
 	}

 clk_dis:
 	clk_disable(pc->clk);
 	return ret;
 }

 static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 	struct device *dev = pc->dev;
 	int ret = 0;

 	/*
 	 * Since we have a common enable for all PWM channels,
 	 * do not enable if already enabled.
 	 */
 	mutex_lock(&pc->sti_pwm_lock);
 	if (!pc->en_count) {
 		ret = clk_enable(pc->clk);
 		if (ret)
 			goto out;

 		ret = regmap_field_write(pc->pwm_en, 1);
 		if (ret) {
 			dev_err(dev, "failed to enable PWM device:%d\n",
 				pwm->hwpwm);
 			goto out;
 		}
 	}
 	pc->en_count++;
 out:
 	mutex_unlock(&pc->sti_pwm_lock);
 	return ret;
 }

 static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);

 	mutex_lock(&pc->sti_pwm_lock);
 	if (--pc->en_count) {
 		mutex_unlock(&pc->sti_pwm_lock);
 		return;
 	}
 	regmap_field_write(pc->pwm_en, 0);

 	clk_disable(pc->clk);
 	mutex_unlock(&pc->sti_pwm_lock);
 }

 static const struct pwm_ops sti_pwm_ops = {
 	.config = sti_pwm_config,
 	.enable = sti_pwm_enable,
 	.disable = sti_pwm_disable,
 	.owner = THIS_MODULE,
 };

 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 {
 	struct device *dev = pc->dev;
 	const struct reg_field *reg_fields;
 	struct device_node *np = dev->of_node;
 	struct sti_pwm_compat_data *cdata = pc->cdata;
 	u32 num_chan;

 	of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
 	if (num_chan)
 		cdata->num_chan = num_chan;

 	reg_fields = cdata->reg_fields;

 	pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
 					reg_fields[PWMCLK_PRESCALE_LOW]);
 	if (IS_ERR(pc->prescale_low))
 		return PTR_ERR(pc->prescale_low);

 	pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
 					reg_fields[PWMCLK_PRESCALE_HIGH]);
 	if (IS_ERR(pc->prescale_high))
 		return PTR_ERR(pc->prescale_high);

 	pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
 					     reg_fields[PWM_EN]);
 	if (IS_ERR(pc->pwm_en))
 		return PTR_ERR(pc->pwm_en);

 	pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
 						 reg_fields[PWM_INT_EN]);
 	if (IS_ERR(pc->pwm_int_en))
 		return PTR_ERR(pc->pwm_int_en);

 	return 0;
 }

 static const struct regmap_config sti_pwm_regmap_config = {
 	.reg_bits = 32,
 	.val_bits = 32,
 	.reg_stride = 4,
 };

 static int sti_pwm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct sti_pwm_compat_data *cdata;
 	struct sti_pwm_chip *pc;
 	struct resource *res;
 	int ret;

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

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

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

 	pc->mmio = devm_ioremap_resource(dev, res);
 	if (IS_ERR(pc->mmio))
 		return PTR_ERR(pc->mmio);

 	pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
 					   &sti_pwm_regmap_config);
 	if (IS_ERR(pc->regmap))
 		return PTR_ERR(pc->regmap);

 	/*
 	 * Setup PWM data with default values: some values could be replaced
 	 * with specific ones provided from Device Tree.
 	 */
 	cdata->reg_fields   = &sti_pwm_regfields[0];
 	cdata->max_prescale = 0xff;
 	cdata->max_pwm_cnt  = 255;
 	cdata->num_chan     = 1;

 	pc->cdata = cdata;
 	pc->dev = dev;
 	pc->en_count = 0;
 	mutex_init(&pc->sti_pwm_lock);

 	ret = sti_pwm_probe_dt(pc);
 	if (ret)
 		return ret;

 	pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
 	if (IS_ERR(pc->clk)) {
 		dev_err(dev, "failed to get PWM clock\n");
 		return PTR_ERR(pc->clk);
 	}

 	pc->clk_rate = clk_get_rate(pc->clk);
 	if (!pc->clk_rate) {
 		dev_err(dev, "failed to get clock rate\n");
 		return -EINVAL;
 	}

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

 	pc->chip.dev = dev;
 	pc->chip.ops = &sti_pwm_ops;
 	pc->chip.base = -1;
 	pc->chip.npwm = pc->cdata->num_chan;
 	pc->chip.can_sleep = true;

 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
 		clk_unprepare(pc->clk);
 		return ret;
 	}

 	platform_set_drvdata(pdev, pc);

 	return 0;
 }

 static int sti_pwm_remove(struct platform_device *pdev)
 {
 	struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
 	unsigned int i;

 	for (i = 0; i < pc->cdata->num_chan; i++)
 		pwm_disable(&pc->chip.pwms[i]);

 	clk_unprepare(pc->clk);

 	return pwmchip_remove(&pc->chip);
 }

 static const struct of_device_id sti_pwm_of_match[] = {
 	{ .compatible = "st,sti-pwm", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sti_pwm_of_match);

 static struct platform_driver sti_pwm_driver = {
 	.driver = {
 		.name = "sti-pwm",
 		.of_match_table = sti_pwm_of_match,
 	},
 	.probe = sti_pwm_probe,
 	.remove = sti_pwm_remove,
 };
 module_platform_driver(sti_pwm_driver);

 MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
 MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
 MODULE_LICENSE("GPL");
	/*
	* PWM device driver for ST SoCs.
	* Author: Ajit Pal Singh <ajitpal.singh@st.com>
	*
	* Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*/

	#include <linux/clk.h>
	#include <linux/math64.h>
	#include <linux/mfd/syscon.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/pwm.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>
	#include <linux/time.h>

	#define STI_DS_REG(ch) (4 * (ch)) /* Channel's Duty Cycle register */
	#define STI_PWMCR 0x50 /* Control/Config register */
	#define STI_INTEN 0x54 /* Interrupt Enable/Disable register */
	#define PWM_PRESCALE_LOW_MASK 0x0f
	#define PWM_PRESCALE_HIGH_MASK 0xf0

	/* Regfield IDs */
	enum {
	PWMCLK_PRESCALE_LOW,
	PWMCLK_PRESCALE_HIGH,
	PWM_EN,
	PWM_INT_EN,

	/* Keep last */
	MAX_REGFIELDS
	};

	struct sti_pwm_compat_data {
	const struct reg_field *reg_fields;
	unsigned int num_chan;
	unsigned int max_pwm_cnt;
	unsigned int max_prescale;
	};

	struct sti_pwm_chip {
	struct device *dev;
	struct clk *clk;
	unsigned long clk_rate;
	struct regmap *regmap;
	struct sti_pwm_compat_data *cdata;
	struct regmap_field *prescale_low;
	struct regmap_field *prescale_high;
	struct regmap_field *pwm_en;
	struct regmap_field *pwm_int_en;
	struct pwm_chip chip;
	struct pwm_device *cur;
	unsigned int en_count;
	struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
	void __iomem *mmio;
	};

	static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
	[PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWMCR, 0, 3),
	[PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWMCR, 11, 14),
	[PWM_EN] = REG_FIELD(STI_PWMCR, 9, 9),
	[PWM_INT_EN] = REG_FIELD(STI_INTEN, 0, 0),
	};

	static inline struct sti_pwm_chip to_sti_pwmchip(struct pwm_chip chip)
	{
	return container_of(chip, struct sti_pwm_chip, chip);
	}

	/*
	* Calculate the prescaler value corresponding to the period.
	*/
	static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
	unsigned int *prescale)
	{
	struct sti_pwm_compat_data *cdata = pc->cdata;
	unsigned long val;
	unsigned int ps;

	/*
	* prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
	*/
	val = NSEC_PER_SEC / pc->clk_rate;
	val *= cdata->max_pwm_cnt + 1;

	if (period % val) {
	return -EINVAL;
	} else {
	ps = period / val - 1;
	if (ps > cdata->max_prescale)
	return -EINVAL;
	}
	*prescale = ps;

	return 0;
	}

	/* Calculate the number of PWM devices configured with a period. */
	static unsigned int sti_pwm_count_configured(struct pwm_chip *chip)
	{
	struct pwm_device *pwm;
	unsigned int ncfg = 0;
	unsigned int i;

	for (i = 0; i < chip->npwm; i++) {
	pwm = &chip->pwms[i];
	if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
	if (pwm_get_period(pwm))
	ncfg++;
	}
	}

	return ncfg;
	}

	/*
	* For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
	* The only way to change the period (apart from changing the PWM input clock)
	* is to change the PWM clock prescaler.
	* The prescaler is of 8 bits, so 256 prescaler values and hence
	* 256 possible period values are supported (for a particular clock rate).
	* The requested period will be applied only if it matches one of these
	* 256 values.
	*/
	static int sti_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
	int duty_ns, int period_ns)
	{
	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
	struct sti_pwm_compat_data *cdata = pc->cdata;
	struct pwm_device *cur = pc->cur;
	struct device *dev = pc->dev;
	unsigned int prescale = 0, pwmvalx;
	int ret;
	unsigned int ncfg;
	bool period_same = false;

	ncfg = sti_pwm_count_configured(chip);
	if (ncfg)
	period_same = (period_ns == pwm_get_period(cur));

	/* Allow configuration changes if one of the
	* following conditions satisfy.
	* 1. No channels have been configured.
	* 2. Only one channel has been configured and the new request
	* is for the same channel.
	* 3. Only one channel has been configured and the new request is
	* for a new channel and period of the new channel is same as
	* the current configured period.
	* 4. More than one channels are configured and period of the new
	* requestis the same as the current period.
	*/
	if (!ncfg \|\|
	((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) \|\|
	((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) \|\|
	((ncfg > 1) && period_same)) {
	/* Enable clock before writing to PWM registers. */
	ret = clk_enable(pc->clk);
	if (ret)
	return ret;

	if (!period_same) {
	ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
	if (ret)
	goto clk_dis;

	ret =
	regmap_field_write(pc->prescale_low,
	prescale & PWM_PRESCALE_LOW_MASK);
	if (ret)
	goto clk_dis;

	ret =
	regmap_field_write(pc->prescale_high,
	(prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
	if (ret)
	goto clk_dis;
	}

	/*
	* When PWMVal == 0, PWM pulse = 1 local clock cycle.
	* When PWMVal == max_pwm_count,
	* PWM pulse = (max_pwm_count + 1) local cycles,
	* that is continuous pulse: signal never goes low.
	*/
	pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;

	ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
	if (ret)
	goto clk_dis;

	ret = regmap_field_write(pc->pwm_int_en, 0);

	pc->cur = pwm;

	dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
	prescale, period_ns, duty_ns, pwmvalx);
	} else {
	return -EINVAL;
	}

	clk_dis:
	clk_disable(pc->clk);
	return ret;
	}

	static int sti_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
	struct device *dev = pc->dev;
	int ret = 0;

	/*
	* Since we have a common enable for all PWM channels,
	* do not enable if already enabled.
	*/
	mutex_lock(&pc->sti_pwm_lock);
	if (!pc->en_count) {
	ret = clk_enable(pc->clk);
	if (ret)
	goto out;

	ret = regmap_field_write(pc->pwm_en, 1);
	if (ret) {
	dev_err(dev, "failed to enable PWM device:%d\n",
	pwm->hwpwm);
	goto out;
	}
	}
	pc->en_count++;
	out:
	mutex_unlock(&pc->sti_pwm_lock);
	return ret;
	}

	static void sti_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);

	mutex_lock(&pc->sti_pwm_lock);
	if (--pc->en_count) {
	mutex_unlock(&pc->sti_pwm_lock);
	return;
	}
	regmap_field_write(pc->pwm_en, 0);

	clk_disable(pc->clk);
	mutex_unlock(&pc->sti_pwm_lock);
	}

	static const struct pwm_ops sti_pwm_ops = {
	.config = sti_pwm_config,
	.enable = sti_pwm_enable,
	.disable = sti_pwm_disable,
	.owner = THIS_MODULE,
	};

	static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
	{
	struct device *dev = pc->dev;
	const struct reg_field *reg_fields;
	struct device_node *np = dev->of_node;
	struct sti_pwm_compat_data *cdata = pc->cdata;
	u32 num_chan;

	of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
	if (num_chan)
	cdata->num_chan = num_chan;

	reg_fields = cdata->reg_fields;

	pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
	reg_fields[PWMCLK_PRESCALE_LOW]);
	if (IS_ERR(pc->prescale_low))
	return PTR_ERR(pc->prescale_low);

	pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
	reg_fields[PWMCLK_PRESCALE_HIGH]);
	if (IS_ERR(pc->prescale_high))
	return PTR_ERR(pc->prescale_high);

	pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
	reg_fields[PWM_EN]);
	if (IS_ERR(pc->pwm_en))
	return PTR_ERR(pc->pwm_en);

	pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
	reg_fields[PWM_INT_EN]);
	if (IS_ERR(pc->pwm_int_en))
	return PTR_ERR(pc->pwm_int_en);

	return 0;
	}

	static const struct regmap_config sti_pwm_regmap_config = {
	.reg_bits = 32,
	.val_bits = 32,
	.reg_stride = 4,
	};

	static int sti_pwm_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct sti_pwm_compat_data *cdata;
	struct sti_pwm_chip *pc;
	struct resource *res;
	int ret;

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

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

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	pc->mmio = devm_ioremap_resource(dev, res);
	if (IS_ERR(pc->mmio))
	return PTR_ERR(pc->mmio);

	pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
	&sti_pwm_regmap_config);
	if (IS_ERR(pc->regmap))
	return PTR_ERR(pc->regmap);

	/*
	* Setup PWM data with default values: some values could be replaced
	* with specific ones provided from Device Tree.
	*/
	cdata->reg_fields = &sti_pwm_regfields[0];
	cdata->max_prescale = 0xff;
	cdata->max_pwm_cnt = 255;
	cdata->num_chan = 1;

	pc->cdata = cdata;
	pc->dev = dev;
	pc->en_count = 0;
	mutex_init(&pc->sti_pwm_lock);

	ret = sti_pwm_probe_dt(pc);
	if (ret)
	return ret;

	pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
	if (IS_ERR(pc->clk)) {
	dev_err(dev, "failed to get PWM clock\n");
	return PTR_ERR(pc->clk);
	}

	pc->clk_rate = clk_get_rate(pc->clk);
	if (!pc->clk_rate) {
	dev_err(dev, "failed to get clock rate\n");
	return -EINVAL;
	}

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

	pc->chip.dev = dev;
	pc->chip.ops = &sti_pwm_ops;
	pc->chip.base = -1;
	pc->chip.npwm = pc->cdata->num_chan;
	pc->chip.can_sleep = true;

	ret = pwmchip_add(&pc->chip);
	if (ret < 0) {
	clk_unprepare(pc->clk);
	return ret;
	}

	platform_set_drvdata(pdev, pc);

	return 0;
	}

	static int sti_pwm_remove(struct platform_device *pdev)
	{
	struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
	unsigned int i;

	for (i = 0; i < pc->cdata->num_chan; i++)
	pwm_disable(&pc->chip.pwms[i]);

	clk_unprepare(pc->clk);

	return pwmchip_remove(&pc->chip);
	}

	static const struct of_device_id sti_pwm_of_match[] = {
	{ .compatible = "st,sti-pwm", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, sti_pwm_of_match);

	static struct platform_driver sti_pwm_driver = {
	.driver = {
	.name = "sti-pwm",
	.of_match_table = sti_pwm_of_match,
	},
	.probe = sti_pwm_probe,
	.remove = sti_pwm_remove,
	};
	module_platform_driver(sti_pwm_driver);

	MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
	MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
	MODULE_LICENSE("GPL");