drivers/pwm/pwm-renesas-tpu.c - kernel/msm-4.19 - Gitiles

 /*
  * R-Mobile TPU PWM driver
  *
  * Copyright (C) 2012 Renesas Solutions Corp.
  *
  * 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
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */

 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/platform_data/pwm-renesas-tpu.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>

 #define TPU_TSTR		0x00	/* Timer start register (shared) */

 #define TPU_TCRn		0x00	/* Timer control register */
 #define TPU_TCR_CCLR_NONE	(0 << 5)
 #define TPU_TCR_CCLR_TGRA	(1 << 5)
 #define TPU_TCR_CCLR_TGRB	(2 << 5)
 #define TPU_TCR_CCLR_TGRC	(5 << 5)
 #define TPU_TCR_CCLR_TGRD	(6 << 5)
 #define TPU_TCR_CKEG_RISING	(0 << 3)
 #define TPU_TCR_CKEG_FALLING	(1 << 3)
 #define TPU_TCR_CKEG_BOTH	(2 << 3)
 #define TPU_TMDRn		0x04	/* Timer mode register */
 #define TPU_TMDR_BFWT		(1 << 6)
 #define TPU_TMDR_BFB		(1 << 5)
 #define TPU_TMDR_BFA		(1 << 4)
 #define TPU_TMDR_MD_NORMAL	(0 << 0)
 #define TPU_TMDR_MD_PWM		(2 << 0)
 #define TPU_TIORn		0x08	/* Timer I/O control register */
 #define TPU_TIOR_IOA_0		(0 << 0)
 #define TPU_TIOR_IOA_0_CLR	(1 << 0)
 #define TPU_TIOR_IOA_0_SET	(2 << 0)
 #define TPU_TIOR_IOA_0_TOGGLE	(3 << 0)
 #define TPU_TIOR_IOA_1		(4 << 0)
 #define TPU_TIOR_IOA_1_CLR	(5 << 0)
 #define TPU_TIOR_IOA_1_SET	(6 << 0)
 #define TPU_TIOR_IOA_1_TOGGLE	(7 << 0)
 #define TPU_TIERn		0x0c	/* Timer interrupt enable register */
 #define TPU_TSRn		0x10	/* Timer status register */
 #define TPU_TCNTn		0x14	/* Timer counter */
 #define TPU_TGRAn		0x18	/* Timer general register A */
 #define TPU_TGRBn		0x1c	/* Timer general register B */
 #define TPU_TGRCn		0x20	/* Timer general register C */
 #define TPU_TGRDn		0x24	/* Timer general register D */

 #define TPU_CHANNEL_OFFSET	0x10
 #define TPU_CHANNEL_SIZE	0x40

 enum tpu_pin_state {
 	TPU_PIN_INACTIVE,		/* Pin is driven inactive */
 	TPU_PIN_PWM,			/* Pin is driven by PWM */
 	TPU_PIN_ACTIVE,			/* Pin is driven active */
 };

 struct tpu_device;

 struct tpu_pwm_device {
 	bool timer_on;			/* Whether the timer is running */

 	struct tpu_device *tpu;
 	unsigned int channel;		/* Channel number in the TPU */

 	enum pwm_polarity polarity;
 	unsigned int prescaler;
 	u16 period;
 	u16 duty;
 };

 struct tpu_device {
 	struct platform_device *pdev;
 	struct tpu_pwm_platform_data *pdata;
 	struct pwm_chip chip;
 	spinlock_t lock;

 	void __iomem *base;
 	struct clk *clk;
 };

 #define to_tpu_device(c)	container_of(c, struct tpu_device, chip)

 static void tpu_pwm_write(struct tpu_pwm_device *pwm, int reg_nr, u16 value)
 {
 	void __iomem *base = pwm->tpu->base + TPU_CHANNEL_OFFSET
 			   + pwm->channel * TPU_CHANNEL_SIZE;

 	iowrite16(value, base + reg_nr);
 }

 static void tpu_pwm_set_pin(struct tpu_pwm_device *pwm,
 			    enum tpu_pin_state state)
 {
 	static const char * const states[] = { "inactive", "PWM", "active" };

 	dev_dbg(&pwm->tpu->pdev->dev, "%u: configuring pin as %s\n",
 		pwm->channel, states[state]);

 	switch (state) {
 	case TPU_PIN_INACTIVE:
 		tpu_pwm_write(pwm, TPU_TIORn,
 			      pwm->polarity == PWM_POLARITY_INVERSED ?
 			      TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0);
 		break;
 	case TPU_PIN_PWM:
 		tpu_pwm_write(pwm, TPU_TIORn,
 			      pwm->polarity == PWM_POLARITY_INVERSED ?
 			      TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR);
 		break;
 	case TPU_PIN_ACTIVE:
 		tpu_pwm_write(pwm, TPU_TIORn,
 			      pwm->polarity == PWM_POLARITY_INVERSED ?
 			      TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1);
 		break;
 	}
 }

 static void tpu_pwm_start_stop(struct tpu_pwm_device *pwm, int start)
 {
 	unsigned long flags;
 	u16 value;

 	spin_lock_irqsave(&pwm->tpu->lock, flags);
 	value = ioread16(pwm->tpu->base + TPU_TSTR);

 	if (start)
 		value |= 1 << pwm->channel;
 	else
 		value &= ~(1 << pwm->channel);

 	iowrite16(value, pwm->tpu->base + TPU_TSTR);
 	spin_unlock_irqrestore(&pwm->tpu->lock, flags);
 }

 static int tpu_pwm_timer_start(struct tpu_pwm_device *pwm)
 {
 	int ret;

 	if (!pwm->timer_on) {
 		/* Wake up device and enable clock. */
 		pm_runtime_get_sync(&pwm->tpu->pdev->dev);
 		ret = clk_prepare_enable(pwm->tpu->clk);
 		if (ret) {
 			dev_err(&pwm->tpu->pdev->dev, "cannot enable clock\n");
 			return ret;
 		}
 		pwm->timer_on = true;
 	}

 	/*
 	 * Make sure the channel is stopped, as we need to reconfigure it
 	 * completely. First drive the pin to the inactive state to avoid
 	 * glitches.
 	 */
 	tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
 	tpu_pwm_start_stop(pwm, false);

 	/*
 	 * - Clear TCNT on TGRB match
 	 * - Count on rising edge
 	 * - Set prescaler
 	 * - Output 0 until TGRA, output 1 until TGRB (active low polarity)
 	 * - Output 1 until TGRA, output 0 until TGRB (active high polarity
 	 * - PWM mode
 	 */
 	tpu_pwm_write(pwm, TPU_TCRn, TPU_TCR_CCLR_TGRB | TPU_TCR_CKEG_RISING |
 		      pwm->prescaler);
 	tpu_pwm_write(pwm, TPU_TMDRn, TPU_TMDR_MD_PWM);
 	tpu_pwm_set_pin(pwm, TPU_PIN_PWM);
 	tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
 	tpu_pwm_write(pwm, TPU_TGRBn, pwm->period);

 	dev_dbg(&pwm->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n",
 		pwm->channel, pwm->duty, pwm->period);

 	/* Start the channel. */
 	tpu_pwm_start_stop(pwm, true);

 	return 0;
 }

 static void tpu_pwm_timer_stop(struct tpu_pwm_device *pwm)
 {
 	if (!pwm->timer_on)
 		return;

 	/* Disable channel. */
 	tpu_pwm_start_stop(pwm, false);

 	/* Stop clock and mark device as idle. */
 	clk_disable_unprepare(pwm->tpu->clk);
 	pm_runtime_put(&pwm->tpu->pdev->dev);

 	pwm->timer_on = false;
 }

 /* -----------------------------------------------------------------------------
  * PWM API
  */

 static int tpu_pwm_request(struct pwm_chip *chip, struct pwm_device *_pwm)
 {
 	struct tpu_device *tpu = to_tpu_device(chip);
 	struct tpu_pwm_device *pwm;

 	if (_pwm->hwpwm >= TPU_CHANNEL_MAX)
 		return -EINVAL;

 	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
 	if (pwm == NULL)
 		return -ENOMEM;

 	pwm->tpu = tpu;
 	pwm->channel = _pwm->hwpwm;
 	pwm->polarity = tpu->pdata ? tpu->pdata->channels[pwm->channel].polarity
 		      : PWM_POLARITY_NORMAL;
 	pwm->prescaler = 0;
 	pwm->period = 0;
 	pwm->duty = 0;

 	pwm->timer_on = false;

 	pwm_set_chip_data(_pwm, pwm);

 	return 0;
 }

 static void tpu_pwm_free(struct pwm_chip *chip, struct pwm_device *_pwm)
 {
 	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);

 	tpu_pwm_timer_stop(pwm);
 	kfree(pwm);
 }

 static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *_pwm,
 			  int duty_ns, int period_ns)
 {
 	static const unsigned int prescalers[] = { 1, 4, 16, 64 };
 	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 	struct tpu_device *tpu = to_tpu_device(chip);
 	unsigned int prescaler;
 	bool duty_only = false;
 	u32 clk_rate;
 	u32 period;
 	u32 duty;
 	int ret;

 	/*
 	 * Pick a prescaler to avoid overflowing the counter.
 	 * TODO: Pick the highest acceptable prescaler.
 	 */
 	clk_rate = clk_get_rate(tpu->clk);

 	for (prescaler = 0; prescaler < ARRAY_SIZE(prescalers); ++prescaler) {
 		period = clk_rate / prescalers[prescaler]
 		       / (NSEC_PER_SEC / period_ns);
 		if (period <= 0xffff)
 			break;
 	}

 	if (prescaler == ARRAY_SIZE(prescalers) || period == 0) {
 		dev_err(&tpu->pdev->dev, "clock rate mismatch\n");
 		return -ENOTSUPP;
 	}

 	if (duty_ns) {
 		duty = clk_rate / prescalers[prescaler]
 		     / (NSEC_PER_SEC / duty_ns);
 		if (duty > period)
 			return -EINVAL;
 	} else {
 		duty = 0;
 	}

 	dev_dbg(&tpu->pdev->dev,
 		"rate %u, prescaler %u, period %u, duty %u\n",
 		clk_rate, prescalers[prescaler], period, duty);

 	if (pwm->prescaler == prescaler && pwm->period == period)
 		duty_only = true;

 	pwm->prescaler = prescaler;
 	pwm->period = period;
 	pwm->duty = duty;

 	/* If the channel is disabled we're done. */
 	if (!test_bit(PWMF_ENABLED, &_pwm->flags))
 		return 0;

 	if (duty_only && pwm->timer_on) {
 		/*
 		 * If only the duty cycle changed and the timer is already
 		 * running, there's no need to reconfigure it completely, Just
 		 * modify the duty cycle.
 		 */
 		tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
 		dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", pwm->channel,
 			pwm->duty);
 	} else {
 		/* Otherwise perform a full reconfiguration. */
 		ret = tpu_pwm_timer_start(pwm);
 		if (ret < 0)
 			return ret;
 	}

 	if (duty == 0 || duty == period) {
 		/*
 		 * To avoid running the timer when not strictly required, handle
 		 * 0% and 100% duty cycles as fixed levels and stop the timer.
 		 */
 		tpu_pwm_set_pin(pwm, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
 		tpu_pwm_timer_stop(pwm);
 	}

 	return 0;
 }

 static int tpu_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *_pwm,
 				enum pwm_polarity polarity)
 {
 	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);

 	pwm->polarity = polarity;

 	return 0;
 }

 static int tpu_pwm_enable(struct pwm_chip *chip, struct pwm_device *_pwm)
 {
 	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 	int ret;

 	ret = tpu_pwm_timer_start(pwm);
 	if (ret < 0)
 		return ret;

 	/*
 	 * To avoid running the timer when not strictly required, handle 0% and
 	 * 100% duty cycles as fixed levels and stop the timer.
 	 */
 	if (pwm->duty == 0 || pwm->duty == pwm->period) {
 		tpu_pwm_set_pin(pwm, pwm->duty ?
 				TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
 		tpu_pwm_timer_stop(pwm);
 	}

 	return 0;
 }

 static void tpu_pwm_disable(struct pwm_chip *chip, struct pwm_device *_pwm)
 {
 	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);

 	/* The timer must be running to modify the pin output configuration. */
 	tpu_pwm_timer_start(pwm);
 	tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
 	tpu_pwm_timer_stop(pwm);
 }

 static const struct pwm_ops tpu_pwm_ops = {
 	.request = tpu_pwm_request,
 	.free = tpu_pwm_free,
 	.config = tpu_pwm_config,
 	.set_polarity = tpu_pwm_set_polarity,
 	.enable = tpu_pwm_enable,
 	.disable = tpu_pwm_disable,
 	.owner = THIS_MODULE,
 };

 /* -----------------------------------------------------------------------------
  * Probe and remove
  */

 static int tpu_probe(struct platform_device *pdev)
 {
 	struct tpu_device *tpu;
 	struct resource *res;
 	int ret;

 	tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL);
 	if (tpu == NULL) {
 		dev_err(&pdev->dev, "failed to allocate driver data\n");
 		return -ENOMEM;
 	}

 	tpu->pdata = pdev->dev.platform_data;

 	/* Map memory, get clock and pin control. */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		dev_err(&pdev->dev, "failed to get I/O memory\n");
 		return -ENXIO;
 	}

 	tpu->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(tpu->base))
 		return PTR_ERR(tpu->base);

 	tpu->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(tpu->clk)) {
 		dev_err(&pdev->dev, "cannot get clock\n");
 		return PTR_ERR(tpu->clk);
 	}

 	/* Initialize and register the device. */
 	platform_set_drvdata(pdev, tpu);

 	spin_lock_init(&tpu->lock);
 	tpu->pdev = pdev;

 	tpu->chip.dev = &pdev->dev;
 	tpu->chip.ops = &tpu_pwm_ops;
 	tpu->chip.base = -1;
 	tpu->chip.npwm = TPU_CHANNEL_MAX;

 	ret = pwmchip_add(&tpu->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to register PWM chip\n");
 		return ret;
 	}

 	dev_info(&pdev->dev, "TPU PWM %d registered\n", tpu->pdev->id);

 	pm_runtime_enable(&pdev->dev);

 	return 0;
 }

 static int tpu_remove(struct platform_device *pdev)
 {
 	struct tpu_device *tpu = platform_get_drvdata(pdev);
 	int ret;

 	ret = pwmchip_remove(&tpu->chip);
 	if (ret)
 		return ret;

 	pm_runtime_disable(&pdev->dev);

 	return 0;
 }

 static struct platform_driver tpu_driver = {
 	.probe		= tpu_probe,
 	.remove		= tpu_remove,
 	.driver		= {
 		.name	= "renesas-tpu-pwm",
 		.owner	= THIS_MODULE,
 	}
 };

 module_platform_driver(tpu_driver);

 MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 MODULE_DESCRIPTION("Renesas TPU PWM Driver");
 MODULE_LICENSE("GPL v2");
	/*
	* R-Mobile TPU PWM driver
	*
	* Copyright (C) 2012 Renesas Solutions Corp.
	*
	* 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
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*/

	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/init.h>
	#include <linux/ioport.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/platform_data/pwm-renesas-tpu.h>
	#include <linux/platform_device.h>
	#include <linux/pm_runtime.h>
	#include <linux/pwm.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>

	#define TPU_TSTR 0x00 /* Timer start register (shared) */

	#define TPU_TCRn 0x00 /* Timer control register */
	#define TPU_TCR_CCLR_NONE (0 << 5)
	#define TPU_TCR_CCLR_TGRA (1 << 5)
	#define TPU_TCR_CCLR_TGRB (2 << 5)
	#define TPU_TCR_CCLR_TGRC (5 << 5)
	#define TPU_TCR_CCLR_TGRD (6 << 5)
	#define TPU_TCR_CKEG_RISING (0 << 3)
	#define TPU_TCR_CKEG_FALLING (1 << 3)
	#define TPU_TCR_CKEG_BOTH (2 << 3)
	#define TPU_TMDRn 0x04 /* Timer mode register */
	#define TPU_TMDR_BFWT (1 << 6)
	#define TPU_TMDR_BFB (1 << 5)
	#define TPU_TMDR_BFA (1 << 4)
	#define TPU_TMDR_MD_NORMAL (0 << 0)
	#define TPU_TMDR_MD_PWM (2 << 0)
	#define TPU_TIORn 0x08 /* Timer I/O control register */
	#define TPU_TIOR_IOA_0 (0 << 0)
	#define TPU_TIOR_IOA_0_CLR (1 << 0)
	#define TPU_TIOR_IOA_0_SET (2 << 0)
	#define TPU_TIOR_IOA_0_TOGGLE (3 << 0)
	#define TPU_TIOR_IOA_1 (4 << 0)
	#define TPU_TIOR_IOA_1_CLR (5 << 0)
	#define TPU_TIOR_IOA_1_SET (6 << 0)
	#define TPU_TIOR_IOA_1_TOGGLE (7 << 0)
	#define TPU_TIERn 0x0c /* Timer interrupt enable register */
	#define TPU_TSRn 0x10 /* Timer status register */
	#define TPU_TCNTn 0x14 /* Timer counter */
	#define TPU_TGRAn 0x18 /* Timer general register A */
	#define TPU_TGRBn 0x1c /* Timer general register B */
	#define TPU_TGRCn 0x20 /* Timer general register C */
	#define TPU_TGRDn 0x24 /* Timer general register D */

	#define TPU_CHANNEL_OFFSET 0x10
	#define TPU_CHANNEL_SIZE 0x40

	enum tpu_pin_state {
	TPU_PIN_INACTIVE, /* Pin is driven inactive */
	TPU_PIN_PWM, /* Pin is driven by PWM */
	TPU_PIN_ACTIVE, /* Pin is driven active */
	};

	struct tpu_device;

	struct tpu_pwm_device {
	bool timer_on; /* Whether the timer is running */

	struct tpu_device *tpu;
	unsigned int channel; /* Channel number in the TPU */

	enum pwm_polarity polarity;
	unsigned int prescaler;
	u16 period;
	u16 duty;
	};

	struct tpu_device {
	struct platform_device *pdev;
	struct tpu_pwm_platform_data *pdata;
	struct pwm_chip chip;
	spinlock_t lock;

	void __iomem *base;
	struct clk *clk;
	};

	#define to_tpu_device(c) container_of(c, struct tpu_device, chip)

	static void tpu_pwm_write(struct tpu_pwm_device *pwm, int reg_nr, u16 value)
	{
	void __iomem *base = pwm->tpu->base + TPU_CHANNEL_OFFSET
	+ pwm->channel * TPU_CHANNEL_SIZE;

	iowrite16(value, base + reg_nr);
	}

	static void tpu_pwm_set_pin(struct tpu_pwm_device *pwm,
	enum tpu_pin_state state)
	{
	static const char * const states[] = { "inactive", "PWM", "active" };

	dev_dbg(&pwm->tpu->pdev->dev, "%u: configuring pin as %s\n",
	pwm->channel, states[state]);

	switch (state) {
	case TPU_PIN_INACTIVE:
	tpu_pwm_write(pwm, TPU_TIORn,
	pwm->polarity == PWM_POLARITY_INVERSED ?
	TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0);
	break;
	case TPU_PIN_PWM:
	tpu_pwm_write(pwm, TPU_TIORn,
	pwm->polarity == PWM_POLARITY_INVERSED ?
	TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR);
	break;
	case TPU_PIN_ACTIVE:
	tpu_pwm_write(pwm, TPU_TIORn,
	pwm->polarity == PWM_POLARITY_INVERSED ?
	TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1);
	break;
	}
	}

	static void tpu_pwm_start_stop(struct tpu_pwm_device *pwm, int start)
	{
	unsigned long flags;
	u16 value;

	spin_lock_irqsave(&pwm->tpu->lock, flags);
	value = ioread16(pwm->tpu->base + TPU_TSTR);

	if (start)
	value \|= 1 << pwm->channel;
	else
	value &= ~(1 << pwm->channel);

	iowrite16(value, pwm->tpu->base + TPU_TSTR);
	spin_unlock_irqrestore(&pwm->tpu->lock, flags);
	}

	static int tpu_pwm_timer_start(struct tpu_pwm_device *pwm)
	{
	int ret;

	if (!pwm->timer_on) {
	/* Wake up device and enable clock. */
	pm_runtime_get_sync(&pwm->tpu->pdev->dev);
	ret = clk_prepare_enable(pwm->tpu->clk);
	if (ret) {
	dev_err(&pwm->tpu->pdev->dev, "cannot enable clock\n");
	return ret;
	}
	pwm->timer_on = true;
	}

	/*
	* Make sure the channel is stopped, as we need to reconfigure it
	* completely. First drive the pin to the inactive state to avoid
	* glitches.
	*/
	tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
	tpu_pwm_start_stop(pwm, false);

	/*
	* - Clear TCNT on TGRB match
	* - Count on rising edge
	* - Set prescaler
	* - Output 0 until TGRA, output 1 until TGRB (active low polarity)
	* - Output 1 until TGRA, output 0 until TGRB (active high polarity
	* - PWM mode
	*/
	tpu_pwm_write(pwm, TPU_TCRn, TPU_TCR_CCLR_TGRB \| TPU_TCR_CKEG_RISING \|
	pwm->prescaler);
	tpu_pwm_write(pwm, TPU_TMDRn, TPU_TMDR_MD_PWM);
	tpu_pwm_set_pin(pwm, TPU_PIN_PWM);
	tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
	tpu_pwm_write(pwm, TPU_TGRBn, pwm->period);

	dev_dbg(&pwm->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n",
	pwm->channel, pwm->duty, pwm->period);

	/* Start the channel. */
	tpu_pwm_start_stop(pwm, true);

	return 0;
	}

	static void tpu_pwm_timer_stop(struct tpu_pwm_device *pwm)
	{
	if (!pwm->timer_on)
	return;

	/* Disable channel. */
	tpu_pwm_start_stop(pwm, false);

	/* Stop clock and mark device as idle. */
	clk_disable_unprepare(pwm->tpu->clk);
	pm_runtime_put(&pwm->tpu->pdev->dev);

	pwm->timer_on = false;
	}

	/* -----------------------------------------------------------------------------
	* PWM API
	*/

	static int tpu_pwm_request(struct pwm_chip chip, struct pwm_device _pwm)
	{
	struct tpu_device *tpu = to_tpu_device(chip);
	struct tpu_pwm_device *pwm;

	if (_pwm->hwpwm >= TPU_CHANNEL_MAX)
	return -EINVAL;

	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
	if (pwm == NULL)
	return -ENOMEM;

	pwm->tpu = tpu;
	pwm->channel = _pwm->hwpwm;
	pwm->polarity = tpu->pdata ? tpu->pdata->channels[pwm->channel].polarity
	: PWM_POLARITY_NORMAL;
	pwm->prescaler = 0;
	pwm->period = 0;
	pwm->duty = 0;

	pwm->timer_on = false;

	pwm_set_chip_data(_pwm, pwm);

	return 0;
	}

	static void tpu_pwm_free(struct pwm_chip chip, struct pwm_device _pwm)
	{
	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);

	tpu_pwm_timer_stop(pwm);
	kfree(pwm);
	}

	static int tpu_pwm_config(struct pwm_chip chip, struct pwm_device _pwm,
	int duty_ns, int period_ns)
	{
	static const unsigned int prescalers[] = { 1, 4, 16, 64 };
	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
	struct tpu_device *tpu = to_tpu_device(chip);
	unsigned int prescaler;
	bool duty_only = false;
	u32 clk_rate;
	u32 period;
	u32 duty;
	int ret;

	/*
	* Pick a prescaler to avoid overflowing the counter.
	* TODO: Pick the highest acceptable prescaler.
	*/
	clk_rate = clk_get_rate(tpu->clk);

	for (prescaler = 0; prescaler < ARRAY_SIZE(prescalers); ++prescaler) {
	period = clk_rate / prescalers[prescaler]
	/ (NSEC_PER_SEC / period_ns);
	if (period <= 0xffff)
	break;
	}

	if (prescaler == ARRAY_SIZE(prescalers) \|\| period == 0) {
	dev_err(&tpu->pdev->dev, "clock rate mismatch\n");
	return -ENOTSUPP;
	}

	if (duty_ns) {
	duty = clk_rate / prescalers[prescaler]
	/ (NSEC_PER_SEC / duty_ns);
	if (duty > period)
	return -EINVAL;
	} else {
	duty = 0;
	}

	dev_dbg(&tpu->pdev->dev,
	"rate %u, prescaler %u, period %u, duty %u\n",
	clk_rate, prescalers[prescaler], period, duty);

	if (pwm->prescaler == prescaler && pwm->period == period)
	duty_only = true;

	pwm->prescaler = prescaler;
	pwm->period = period;
	pwm->duty = duty;

	/* If the channel is disabled we're done. */
	if (!test_bit(PWMF_ENABLED, &_pwm->flags))
	return 0;

	if (duty_only && pwm->timer_on) {
	/*
	* If only the duty cycle changed and the timer is already
	* running, there's no need to reconfigure it completely, Just
	* modify the duty cycle.
	*/
	tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
	dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", pwm->channel,
	pwm->duty);
	} else {
	/* Otherwise perform a full reconfiguration. */
	ret = tpu_pwm_timer_start(pwm);
	if (ret < 0)
	return ret;
	}

	if (duty == 0 \|\| duty == period) {
	/*
	* To avoid running the timer when not strictly required, handle
	* 0% and 100% duty cycles as fixed levels and stop the timer.
	*/
	tpu_pwm_set_pin(pwm, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
	tpu_pwm_timer_stop(pwm);
	}

	return 0;
	}

	static int tpu_pwm_set_polarity(struct pwm_chip chip, struct pwm_device _pwm,
	enum pwm_polarity polarity)
	{
	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);

	pwm->polarity = polarity;

	return 0;
	}

	static int tpu_pwm_enable(struct pwm_chip chip, struct pwm_device _pwm)
	{
	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
	int ret;

	ret = tpu_pwm_timer_start(pwm);
	if (ret < 0)
	return ret;

	/*
	* To avoid running the timer when not strictly required, handle 0% and
	* 100% duty cycles as fixed levels and stop the timer.
	*/
	if (pwm->duty == 0 \|\| pwm->duty == pwm->period) {
	tpu_pwm_set_pin(pwm, pwm->duty ?
	TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
	tpu_pwm_timer_stop(pwm);
	}

	return 0;
	}

	static void tpu_pwm_disable(struct pwm_chip chip, struct pwm_device _pwm)
	{
	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);

	/* The timer must be running to modify the pin output configuration. */
	tpu_pwm_timer_start(pwm);
	tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
	tpu_pwm_timer_stop(pwm);
	}

	static const struct pwm_ops tpu_pwm_ops = {
	.request = tpu_pwm_request,
	.free = tpu_pwm_free,
	.config = tpu_pwm_config,
	.set_polarity = tpu_pwm_set_polarity,
	.enable = tpu_pwm_enable,
	.disable = tpu_pwm_disable,
	.owner = THIS_MODULE,
	};

	/* -----------------------------------------------------------------------------
	* Probe and remove
	*/

	static int tpu_probe(struct platform_device *pdev)
	{
	struct tpu_device *tpu;
	struct resource *res;
	int ret;

	tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL);
	if (tpu == NULL) {
	dev_err(&pdev->dev, "failed to allocate driver data\n");
	return -ENOMEM;
	}

	tpu->pdata = pdev->dev.platform_data;

	/* Map memory, get clock and pin control. */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	dev_err(&pdev->dev, "failed to get I/O memory\n");
	return -ENXIO;
	}

	tpu->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(tpu->base))
	return PTR_ERR(tpu->base);

	tpu->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(tpu->clk)) {
	dev_err(&pdev->dev, "cannot get clock\n");
	return PTR_ERR(tpu->clk);
	}

	/* Initialize and register the device. */
	platform_set_drvdata(pdev, tpu);

	spin_lock_init(&tpu->lock);
	tpu->pdev = pdev;

	tpu->chip.dev = &pdev->dev;
	tpu->chip.ops = &tpu_pwm_ops;
	tpu->chip.base = -1;
	tpu->chip.npwm = TPU_CHANNEL_MAX;

	ret = pwmchip_add(&tpu->chip);
	if (ret < 0) {
	dev_err(&pdev->dev, "failed to register PWM chip\n");
	return ret;
	}

	dev_info(&pdev->dev, "TPU PWM %d registered\n", tpu->pdev->id);

	pm_runtime_enable(&pdev->dev);

	return 0;
	}

	static int tpu_remove(struct platform_device *pdev)
	{
	struct tpu_device *tpu = platform_get_drvdata(pdev);
	int ret;

	ret = pwmchip_remove(&tpu->chip);
	if (ret)
	return ret;

	pm_runtime_disable(&pdev->dev);

	return 0;
	}

	static struct platform_driver tpu_driver = {
	.probe = tpu_probe,
	.remove = tpu_remove,
	.driver = {
	.name = "renesas-tpu-pwm",
	.owner = THIS_MODULE,
	}
	};

	module_platform_driver(tpu_driver);

	MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
	MODULE_DESCRIPTION("Renesas TPU PWM Driver");
	MODULE_LICENSE("GPL v2");