drivers/pwm/pwm-lpc18xx-sct.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
  *
  * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
  *
  * Notes
  * =====
  * NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
  * as a Pulse Width Modulator.
  *
  * SCT supports 16 outputs, 16 events and 16 registers. Each event will be
  * triggered when its related register matches the SCT counter value, and it
  * will set or clear a selected output.
  *
  * One of the events is preselected to generate the period, thus the maximum
  * number of simultaneous channels is limited to 15. Notice that period is
  * global to all the channels, thus PWM driver will refuse setting different
  * values to it, unless there's only one channel requested.
  */

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

 /* LPC18xx SCT registers */
 #define LPC18XX_PWM_CONFIG		0x000
 #define LPC18XX_PWM_CONFIG_UNIFY	BIT(0)
 #define LPC18XX_PWM_CONFIG_NORELOAD	BIT(7)

 #define LPC18XX_PWM_CTRL		0x004
 #define LPC18XX_PWM_CTRL_HALT		BIT(2)
 #define LPC18XX_PWM_BIDIR		BIT(4)
 #define LPC18XX_PWM_PRE_SHIFT		5
 #define LPC18XX_PWM_PRE_MASK		(0xff << LPC18XX_PWM_PRE_SHIFT)
 #define LPC18XX_PWM_PRE(x)		(x << LPC18XX_PWM_PRE_SHIFT)

 #define LPC18XX_PWM_LIMIT		0x008

 #define LPC18XX_PWM_RES_BASE		0x058
 #define LPC18XX_PWM_RES_SHIFT(_ch)	(_ch * 2)
 #define LPC18XX_PWM_RES(_ch, _action)	(_action << LPC18XX_PWM_RES_SHIFT(_ch))
 #define LPC18XX_PWM_RES_MASK(_ch)	(0x3 << LPC18XX_PWM_RES_SHIFT(_ch))

 #define LPC18XX_PWM_MATCH_BASE		0x100
 #define LPC18XX_PWM_MATCH(_ch)		(LPC18XX_PWM_MATCH_BASE + _ch * 4)

 #define LPC18XX_PWM_MATCHREL_BASE	0x200
 #define LPC18XX_PWM_MATCHREL(_ch)	(LPC18XX_PWM_MATCHREL_BASE + _ch * 4)

 #define LPC18XX_PWM_EVSTATEMSK_BASE	0x300
 #define LPC18XX_PWM_EVSTATEMSK(_ch)	(LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
 #define LPC18XX_PWM_EVSTATEMSK_ALL	0xffffffff

 #define LPC18XX_PWM_EVCTRL_BASE		0x304
 #define LPC18XX_PWM_EVCTRL(_ev)		(LPC18XX_PWM_EVCTRL_BASE + _ev * 8)

 #define LPC18XX_PWM_EVCTRL_MATCH(_ch)	_ch

 #define LPC18XX_PWM_EVCTRL_COMB_SHIFT	12
 #define LPC18XX_PWM_EVCTRL_COMB_MATCH	(0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)

 #define LPC18XX_PWM_OUTPUTSET_BASE	0x500
 #define LPC18XX_PWM_OUTPUTSET(_ch)	(LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)

 #define LPC18XX_PWM_OUTPUTCL_BASE	0x504
 #define LPC18XX_PWM_OUTPUTCL(_ch)	(LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)

 /* LPC18xx SCT unified counter */
 #define LPC18XX_PWM_TIMER_MAX		0xffffffff

 /* LPC18xx SCT events */
 #define LPC18XX_PWM_EVENT_PERIOD	0
 #define LPC18XX_PWM_EVENT_MAX		16

 /* SCT conflict resolution */
 enum lpc18xx_pwm_res_action {
 	LPC18XX_PWM_RES_NONE,
 	LPC18XX_PWM_RES_SET,
 	LPC18XX_PWM_RES_CLEAR,
 	LPC18XX_PWM_RES_TOGGLE,
 };

 struct lpc18xx_pwm_data {
 	unsigned int duty_event;
 };

 struct lpc18xx_pwm_chip {
 	struct device *dev;
 	struct pwm_chip chip;
 	void __iomem *base;
 	struct clk *pwm_clk;
 	unsigned long clk_rate;
 	unsigned int period_ns;
 	unsigned int min_period_ns;
 	unsigned int max_period_ns;
 	unsigned int period_event;
 	unsigned long event_map;
 	struct mutex res_lock;
 	struct mutex period_lock;
 };

 static inline struct lpc18xx_pwm_chip *
 to_lpc18xx_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct lpc18xx_pwm_chip, chip);
 }

 static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 				      u32 reg, u32 val)
 {
 	writel(val, lpc18xx_pwm->base + reg);
 }

 static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 				    u32 reg)
 {
 	return readl(lpc18xx_pwm->base + reg);
 }

 static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 					 struct pwm_device *pwm,
 					 enum lpc18xx_pwm_res_action action)
 {
 	u32 val;

 	mutex_lock(&lpc18xx_pwm->res_lock);

 	/*
 	 * Simultaneous set and clear may happen on an output, that is the case
 	 * when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
 	 * resolution action to be taken in such a case.
 	 */
 	val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
 	val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
 	val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);

 	mutex_unlock(&lpc18xx_pwm->res_lock);
 }

 static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	u64 val;

 	val = (u64)period_ns * lpc18xx_pwm->clk_rate;
 	do_div(val, NSEC_PER_SEC);

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
 			   (u32)val - 1);

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
 			   (u32)val - 1);
 }

 static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
 				    struct pwm_device *pwm, int duty_ns)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 	u64 val;

 	val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
 	do_div(val, NSEC_PER_SEC);

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
 			   (u32)val);

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
 			   (u32)val);
 }

 static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			      int duty_ns, int period_ns)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	int requested_events, i;

 	if (period_ns < lpc18xx_pwm->min_period_ns ||
 	    period_ns > lpc18xx_pwm->max_period_ns) {
 		dev_err(chip->dev, "period %d not in range\n", period_ns);
 		return -ERANGE;
 	}

 	mutex_lock(&lpc18xx_pwm->period_lock);

 	requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
 					 LPC18XX_PWM_EVENT_MAX);

 	/*
 	 * The PWM supports only a single period for all PWM channels.
 	 * Once the period is set, it can only be changed if no more than one
 	 * channel is requested at that moment.
 	 */
 	if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
 	    lpc18xx_pwm->period_ns) {
 		dev_err(chip->dev, "conflicting period requested for PWM %u\n",
 			pwm->hwpwm);
 		mutex_unlock(&lpc18xx_pwm->period_lock);
 		return -EBUSY;
 	}

 	if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
 	    !lpc18xx_pwm->period_ns) {
 		lpc18xx_pwm->period_ns = period_ns;
 		for (i = 0; i < chip->npwm; i++)
 			pwm_set_period(&chip->pwms[i], period_ns);
 		lpc18xx_pwm_config_period(chip, period_ns);
 	}

 	mutex_unlock(&lpc18xx_pwm->period_lock);

 	lpc18xx_pwm_config_duty(chip, pwm, duty_ns);

 	return 0;
 }

 static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
 				    struct pwm_device *pwm,
 				    enum pwm_polarity polarity)
 {
 	return 0;
 }

 static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 	enum lpc18xx_pwm_res_action res_action;
 	unsigned int set_event, clear_event;

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
 			   LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
 			   LPC18XX_PWM_EVCTRL_COMB_MATCH);

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
 			   LPC18XX_PWM_EVSTATEMSK_ALL);

 	if (pwm_get_polarity(pwm) == PWM_POLARITY_NORMAL) {
 		set_event = lpc18xx_pwm->period_event;
 		clear_event = lpc18xx_data->duty_event;
 		res_action = LPC18XX_PWM_RES_SET;
 	} else {
 		set_event = lpc18xx_data->duty_event;
 		clear_event = lpc18xx_pwm->period_event;
 		res_action = LPC18XX_PWM_RES_CLEAR;
 	}

 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
 			   BIT(set_event));
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
 			   BIT(clear_event));
 	lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);

 	return 0;
 }

 static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
 }

 static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 	unsigned long event;

 	event = find_first_zero_bit(&lpc18xx_pwm->event_map,
 				    LPC18XX_PWM_EVENT_MAX);

 	if (event >= LPC18XX_PWM_EVENT_MAX) {
 		dev_err(lpc18xx_pwm->dev,
 			"maximum number of simultaneous channels reached\n");
 		return -EBUSY;
 	}

 	set_bit(event, &lpc18xx_pwm->event_map);
 	lpc18xx_data->duty_event = event;

 	return 0;
 }

 static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);

 	clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
 }

 static const struct pwm_ops lpc18xx_pwm_ops = {
 	.config = lpc18xx_pwm_config,
 	.set_polarity = lpc18xx_pwm_set_polarity,
 	.enable = lpc18xx_pwm_enable,
 	.disable = lpc18xx_pwm_disable,
 	.request = lpc18xx_pwm_request,
 	.free = lpc18xx_pwm_free,
 	.owner = THIS_MODULE,
 };

 static const struct of_device_id lpc18xx_pwm_of_match[] = {
 	{ .compatible = "nxp,lpc1850-sct-pwm" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);

 static int lpc18xx_pwm_probe(struct platform_device *pdev)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm;
 	struct pwm_device *pwm;
 	int ret, i;
 	u64 val;

 	lpc18xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*lpc18xx_pwm),
 				   GFP_KERNEL);
 	if (!lpc18xx_pwm)
 		return -ENOMEM;

 	lpc18xx_pwm->dev = &pdev->dev;

 	lpc18xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(lpc18xx_pwm->base))
 		return PTR_ERR(lpc18xx_pwm->base);

 	lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
 	if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
 		dev_err(&pdev->dev, "failed to get pwm clock\n");
 		return PTR_ERR(lpc18xx_pwm->pwm_clk);
 	}

 	ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
 		return ret;
 	}

 	lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
 	if (!lpc18xx_pwm->clk_rate) {
 		dev_err(&pdev->dev, "pwm clock has no frequency\n");
 		ret = -EINVAL;
 		goto disable_pwmclk;
 	}

 	mutex_init(&lpc18xx_pwm->res_lock);
 	mutex_init(&lpc18xx_pwm->period_lock);

 	val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
 	do_div(val, lpc18xx_pwm->clk_rate);
 	lpc18xx_pwm->max_period_ns = val;

 	lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
 						  lpc18xx_pwm->clk_rate);

 	lpc18xx_pwm->chip.dev = &pdev->dev;
 	lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops;
 	lpc18xx_pwm->chip.base = -1;
 	lpc18xx_pwm->chip.npwm = 16;
 	lpc18xx_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 	lpc18xx_pwm->chip.of_pwm_n_cells = 3;

 	/* SCT counter must be in unify (32 bit) mode */
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
 			   LPC18XX_PWM_CONFIG_UNIFY);

 	/*
 	 * Everytime the timer counter reaches the period value, the related
 	 * event will be triggered and the counter reset to 0.
 	 */
 	set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
 	lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;

 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
 			   LPC18XX_PWM_EVSTATEMSK_ALL);

 	val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
 	      LPC18XX_PWM_EVCTRL_COMB_MATCH;
 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);

 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
 			   BIT(lpc18xx_pwm->period_event));

 	ret = pwmchip_add(&lpc18xx_pwm->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
 		goto disable_pwmclk;
 	}

 	for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
 		struct lpc18xx_pwm_data *data;

 		pwm = &lpc18xx_pwm->chip.pwms[i];

 		data = devm_kzalloc(lpc18xx_pwm->dev, sizeof(*data),
 				    GFP_KERNEL);
 		if (!data) {
 			ret = -ENOMEM;
 			goto remove_pwmchip;
 		}

 		pwm_set_chip_data(pwm, data);
 	}

 	platform_set_drvdata(pdev, lpc18xx_pwm);

 	val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
 	val &= ~LPC18XX_PWM_BIDIR;
 	val &= ~LPC18XX_PWM_CTRL_HALT;
 	val &= ~LPC18XX_PWM_PRE_MASK;
 	val |= LPC18XX_PWM_PRE(0);
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);

 	return 0;

 remove_pwmchip:
 	pwmchip_remove(&lpc18xx_pwm->chip);
 disable_pwmclk:
 	clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
 	return ret;
 }

 static int lpc18xx_pwm_remove(struct platform_device *pdev)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = platform_get_drvdata(pdev);
 	u32 val;

 	val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
 	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
 			   val | LPC18XX_PWM_CTRL_HALT);

 	clk_disable_unprepare(lpc18xx_pwm->pwm_clk);

 	return pwmchip_remove(&lpc18xx_pwm->chip);
 }

 static struct platform_driver lpc18xx_pwm_driver = {
 	.driver = {
 		.name = "lpc18xx-sct-pwm",
 		.of_match_table = lpc18xx_pwm_of_match,
 	},
 	.probe = lpc18xx_pwm_probe,
 	.remove = lpc18xx_pwm_remove,
 };
 module_platform_driver(lpc18xx_pwm_driver);

 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
 MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
	*
	* Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
	*
	* Notes
	* =====
	* NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
	* as a Pulse Width Modulator.
	*
	* SCT supports 16 outputs, 16 events and 16 registers. Each event will be
	* triggered when its related register matches the SCT counter value, and it
	* will set or clear a selected output.
	*
	* One of the events is preselected to generate the period, thus the maximum
	* number of simultaneous channels is limited to 15. Notice that period is
	* global to all the channels, thus PWM driver will refuse setting different
	* values to it, unless there's only one channel requested.
	*/

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

	/* LPC18xx SCT registers */
	#define LPC18XX_PWM_CONFIG 0x000
	#define LPC18XX_PWM_CONFIG_UNIFY BIT(0)
	#define LPC18XX_PWM_CONFIG_NORELOAD BIT(7)

	#define LPC18XX_PWM_CTRL 0x004
	#define LPC18XX_PWM_CTRL_HALT BIT(2)
	#define LPC18XX_PWM_BIDIR BIT(4)
	#define LPC18XX_PWM_PRE_SHIFT 5
	#define LPC18XX_PWM_PRE_MASK (0xff << LPC18XX_PWM_PRE_SHIFT)
	#define LPC18XX_PWM_PRE(x) (x << LPC18XX_PWM_PRE_SHIFT)

	#define LPC18XX_PWM_LIMIT 0x008

	#define LPC18XX_PWM_RES_BASE 0x058
	#define LPC18XX_PWM_RES_SHIFT(_ch) (_ch * 2)
	#define LPC18XX_PWM_RES(_ch, _action) (_action << LPC18XX_PWM_RES_SHIFT(_ch))
	#define LPC18XX_PWM_RES_MASK(_ch) (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))

	#define LPC18XX_PWM_MATCH_BASE 0x100
	#define LPC18XX_PWM_MATCH(_ch) (LPC18XX_PWM_MATCH_BASE + _ch * 4)

	#define LPC18XX_PWM_MATCHREL_BASE 0x200
	#define LPC18XX_PWM_MATCHREL(_ch) (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)

	#define LPC18XX_PWM_EVSTATEMSK_BASE 0x300
	#define LPC18XX_PWM_EVSTATEMSK(_ch) (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
	#define LPC18XX_PWM_EVSTATEMSK_ALL 0xffffffff

	#define LPC18XX_PWM_EVCTRL_BASE 0x304
	#define LPC18XX_PWM_EVCTRL(_ev) (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)

	#define LPC18XX_PWM_EVCTRL_MATCH(_ch) _ch

	#define LPC18XX_PWM_EVCTRL_COMB_SHIFT 12
	#define LPC18XX_PWM_EVCTRL_COMB_MATCH (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)

	#define LPC18XX_PWM_OUTPUTSET_BASE 0x500
	#define LPC18XX_PWM_OUTPUTSET(_ch) (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)

	#define LPC18XX_PWM_OUTPUTCL_BASE 0x504
	#define LPC18XX_PWM_OUTPUTCL(_ch) (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)

	/* LPC18xx SCT unified counter */
	#define LPC18XX_PWM_TIMER_MAX 0xffffffff

	/* LPC18xx SCT events */
	#define LPC18XX_PWM_EVENT_PERIOD 0
	#define LPC18XX_PWM_EVENT_MAX 16

	/* SCT conflict resolution */
	enum lpc18xx_pwm_res_action {
	LPC18XX_PWM_RES_NONE,
	LPC18XX_PWM_RES_SET,
	LPC18XX_PWM_RES_CLEAR,
	LPC18XX_PWM_RES_TOGGLE,
	};

	struct lpc18xx_pwm_data {
	unsigned int duty_event;
	};

	struct lpc18xx_pwm_chip {
	struct device *dev;
	struct pwm_chip chip;
	void __iomem *base;
	struct clk *pwm_clk;
	unsigned long clk_rate;
	unsigned int period_ns;
	unsigned int min_period_ns;
	unsigned int max_period_ns;
	unsigned int period_event;
	unsigned long event_map;
	struct mutex res_lock;
	struct mutex period_lock;
	};

	static inline struct lpc18xx_pwm_chip *
	to_lpc18xx_pwm_chip(struct pwm_chip *chip)
	{
	return container_of(chip, struct lpc18xx_pwm_chip, chip);
	}

	static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
	u32 reg, u32 val)
	{
	writel(val, lpc18xx_pwm->base + reg);
	}

	static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
	u32 reg)
	{
	return readl(lpc18xx_pwm->base + reg);
	}

	static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
	struct pwm_device *pwm,
	enum lpc18xx_pwm_res_action action)
	{
	u32 val;

	mutex_lock(&lpc18xx_pwm->res_lock);

	/*
	* Simultaneous set and clear may happen on an output, that is the case
	* when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
	* resolution action to be taken in such a case.
	*/
	val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
	val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
	val \|= LPC18XX_PWM_RES(pwm->hwpwm, action);
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);

	mutex_unlock(&lpc18xx_pwm->res_lock);
	}

	static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	u64 val;

	val = (u64)period_ns * lpc18xx_pwm->clk_rate;
	do_div(val, NSEC_PER_SEC);

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
	(u32)val - 1);

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
	(u32)val - 1);
	}

	static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
	struct pwm_device *pwm, int duty_ns)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
	u64 val;

	val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
	do_div(val, NSEC_PER_SEC);

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
	(u32)val);

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
	(u32)val);
	}

	static int lpc18xx_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
	int duty_ns, int period_ns)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	int requested_events, i;

	if (period_ns < lpc18xx_pwm->min_period_ns \|\|
	period_ns > lpc18xx_pwm->max_period_ns) {
	dev_err(chip->dev, "period %d not in range\n", period_ns);
	return -ERANGE;
	}

	mutex_lock(&lpc18xx_pwm->period_lock);

	requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
	LPC18XX_PWM_EVENT_MAX);

	/*
	* The PWM supports only a single period for all PWM channels.
	* Once the period is set, it can only be changed if no more than one
	* channel is requested at that moment.
	*/
	if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
	lpc18xx_pwm->period_ns) {
	dev_err(chip->dev, "conflicting period requested for PWM %u\n",
	pwm->hwpwm);
	mutex_unlock(&lpc18xx_pwm->period_lock);
	return -EBUSY;
	}

	if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) \|\|
	!lpc18xx_pwm->period_ns) {
	lpc18xx_pwm->period_ns = period_ns;
	for (i = 0; i < chip->npwm; i++)
	pwm_set_period(&chip->pwms[i], period_ns);
	lpc18xx_pwm_config_period(chip, period_ns);
	}

	mutex_unlock(&lpc18xx_pwm->period_lock);

	lpc18xx_pwm_config_duty(chip, pwm, duty_ns);

	return 0;
	}

	static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
	struct pwm_device *pwm,
	enum pwm_polarity polarity)
	{
	return 0;
	}

	static int lpc18xx_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
	enum lpc18xx_pwm_res_action res_action;
	unsigned int set_event, clear_event;

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
	LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) \|
	LPC18XX_PWM_EVCTRL_COMB_MATCH);

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
	LPC18XX_PWM_EVSTATEMSK_ALL);

	if (pwm_get_polarity(pwm) == PWM_POLARITY_NORMAL) {
	set_event = lpc18xx_pwm->period_event;
	clear_event = lpc18xx_data->duty_event;
	res_action = LPC18XX_PWM_RES_SET;
	} else {
	set_event = lpc18xx_data->duty_event;
	clear_event = lpc18xx_pwm->period_event;
	res_action = LPC18XX_PWM_RES_CLEAR;
	}

	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
	BIT(set_event));
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
	BIT(clear_event));
	lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);

	return 0;
	}

	static void lpc18xx_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
	}

	static int lpc18xx_pwm_request(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
	unsigned long event;

	event = find_first_zero_bit(&lpc18xx_pwm->event_map,
	LPC18XX_PWM_EVENT_MAX);

	if (event >= LPC18XX_PWM_EVENT_MAX) {
	dev_err(lpc18xx_pwm->dev,
	"maximum number of simultaneous channels reached\n");
	return -EBUSY;
	}

	set_bit(event, &lpc18xx_pwm->event_map);
	lpc18xx_data->duty_event = event;

	return 0;
	}

	static void lpc18xx_pwm_free(struct pwm_chip chip, struct pwm_device pwm)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
	struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);

	clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
	}

	static const struct pwm_ops lpc18xx_pwm_ops = {
	.config = lpc18xx_pwm_config,
	.set_polarity = lpc18xx_pwm_set_polarity,
	.enable = lpc18xx_pwm_enable,
	.disable = lpc18xx_pwm_disable,
	.request = lpc18xx_pwm_request,
	.free = lpc18xx_pwm_free,
	.owner = THIS_MODULE,
	};

	static const struct of_device_id lpc18xx_pwm_of_match[] = {
	{ .compatible = "nxp,lpc1850-sct-pwm" },
	{}
	};
	MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);

	static int lpc18xx_pwm_probe(struct platform_device *pdev)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm;
	struct pwm_device *pwm;
	int ret, i;
	u64 val;

	lpc18xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*lpc18xx_pwm),
	GFP_KERNEL);
	if (!lpc18xx_pwm)
	return -ENOMEM;

	lpc18xx_pwm->dev = &pdev->dev;

	lpc18xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(lpc18xx_pwm->base))
	return PTR_ERR(lpc18xx_pwm->base);

	lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
	if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
	dev_err(&pdev->dev, "failed to get pwm clock\n");
	return PTR_ERR(lpc18xx_pwm->pwm_clk);
	}

	ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
	if (ret < 0) {
	dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
	return ret;
	}

	lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
	if (!lpc18xx_pwm->clk_rate) {
	dev_err(&pdev->dev, "pwm clock has no frequency\n");
	ret = -EINVAL;
	goto disable_pwmclk;
	}

	mutex_init(&lpc18xx_pwm->res_lock);
	mutex_init(&lpc18xx_pwm->period_lock);

	val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
	do_div(val, lpc18xx_pwm->clk_rate);
	lpc18xx_pwm->max_period_ns = val;

	lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
	lpc18xx_pwm->clk_rate);

	lpc18xx_pwm->chip.dev = &pdev->dev;
	lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops;
	lpc18xx_pwm->chip.base = -1;
	lpc18xx_pwm->chip.npwm = 16;
	lpc18xx_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
	lpc18xx_pwm->chip.of_pwm_n_cells = 3;

	/* SCT counter must be in unify (32 bit) mode */
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
	LPC18XX_PWM_CONFIG_UNIFY);

	/*
	* Everytime the timer counter reaches the period value, the related
	* event will be triggered and the counter reset to 0.
	*/
	set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
	lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;

	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
	LPC18XX_PWM_EVSTATEMSK_ALL);

	val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) \|
	LPC18XX_PWM_EVCTRL_COMB_MATCH;
	lpc18xx_pwm_writel(lpc18xx_pwm,
	LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);

	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
	BIT(lpc18xx_pwm->period_event));

	ret = pwmchip_add(&lpc18xx_pwm->chip);
	if (ret < 0) {
	dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
	goto disable_pwmclk;
	}

	for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
	struct lpc18xx_pwm_data *data;

	pwm = &lpc18xx_pwm->chip.pwms[i];

	data = devm_kzalloc(lpc18xx_pwm->dev, sizeof(*data),
	GFP_KERNEL);
	if (!data) {
	ret = -ENOMEM;
	goto remove_pwmchip;
	}

	pwm_set_chip_data(pwm, data);
	}

	platform_set_drvdata(pdev, lpc18xx_pwm);

	val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
	val &= ~LPC18XX_PWM_BIDIR;
	val &= ~LPC18XX_PWM_CTRL_HALT;
	val &= ~LPC18XX_PWM_PRE_MASK;
	val \|= LPC18XX_PWM_PRE(0);
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);

	return 0;

	remove_pwmchip:
	pwmchip_remove(&lpc18xx_pwm->chip);
	disable_pwmclk:
	clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
	return ret;
	}

	static int lpc18xx_pwm_remove(struct platform_device *pdev)
	{
	struct lpc18xx_pwm_chip *lpc18xx_pwm = platform_get_drvdata(pdev);
	u32 val;

	val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
	lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
	val \| LPC18XX_PWM_CTRL_HALT);

	clk_disable_unprepare(lpc18xx_pwm->pwm_clk);

	return pwmchip_remove(&lpc18xx_pwm->chip);
	}

	static struct platform_driver lpc18xx_pwm_driver = {
	.driver = {
	.name = "lpc18xx-sct-pwm",
	.of_match_table = lpc18xx_pwm_of_match,
	},
	.probe = lpc18xx_pwm_probe,
	.remove = lpc18xx_pwm_remove,
	};
	module_platform_driver(lpc18xx_pwm_driver);

	MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
	MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
	MODULE_LICENSE("GPL v2");