// SPDX-License-Identifier: GPL-2.0

  /*
   * simple driver for PWM (Pulse Width Modulator) controller
   *

   * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>

   *
   * Limitations:
   * - When disabled the output is driven to 0 independent of the configured
   *   polarity.

   */

  #include <linux/bitfield.h>
  #include <linux/bitops.h>

  #include <linux/clk.h>

  #include <linux/delay.h>

  #include <linux/err.h>

  #include <linux/io.h>

  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/of.h>

  #include <linux/platform_device.h>
  #include <linux/pwm.h>
  #include <linux/slab.h>

  #define MX3_PWMCR			0x00    /* PWM Control Register */

  #define MX3_PWMSR			0x04    /* PWM Status Register */

  #define MX3_PWMSAR			0x0C    /* PWM Sample Register */
  #define MX3_PWMPR			0x10    /* PWM Period Register */

  
  #define MX3_PWMCR_FWM			GENMASK(27, 26)
  #define MX3_PWMCR_STOPEN		BIT(25)
  #define MX3_PWMCR_DOZEN			BIT(24)
  #define MX3_PWMCR_WAITEN		BIT(23)
  #define MX3_PWMCR_DBGEN			BIT(22)
  #define MX3_PWMCR_BCTR			BIT(21)
  #define MX3_PWMCR_HCTR			BIT(20)
  
  #define MX3_PWMCR_POUTC			GENMASK(19, 18)
  #define MX3_PWMCR_POUTC_NORMAL		0
  #define MX3_PWMCR_POUTC_INVERTED	1
  #define MX3_PWMCR_POUTC_OFF		2
  
  #define MX3_PWMCR_CLKSRC		GENMASK(17, 16)
  #define MX3_PWMCR_CLKSRC_OFF		0
  #define MX3_PWMCR_CLKSRC_IPG		1
  #define MX3_PWMCR_CLKSRC_IPG_HIGH	2
  #define MX3_PWMCR_CLKSRC_IPG_32K	3
  
  #define MX3_PWMCR_PRESCALER		GENMASK(15, 4)
  
  #define MX3_PWMCR_SWR			BIT(3)
  
  #define MX3_PWMCR_REPEAT		GENMASK(2, 1)
  #define MX3_PWMCR_REPEAT_1X		0
  #define MX3_PWMCR_REPEAT_2X		1
  #define MX3_PWMCR_REPEAT_4X		2
  #define MX3_PWMCR_REPEAT_8X		3
  
  #define MX3_PWMCR_EN			BIT(0)
  
  #define MX3_PWMSR_FWE			BIT(6)
  #define MX3_PWMSR_CMP			BIT(5)
  #define MX3_PWMSR_ROV			BIT(4)
  #define MX3_PWMSR_FE			BIT(3)
  
  #define MX3_PWMSR_FIFOAV		GENMASK(2, 0)
  #define MX3_PWMSR_FIFOAV_EMPTY		0
  #define MX3_PWMSR_FIFOAV_1WORD		1
  #define MX3_PWMSR_FIFOAV_2WORDS		2
  #define MX3_PWMSR_FIFOAV_3WORDS		3
  #define MX3_PWMSR_FIFOAV_4WORDS		4
  
  #define MX3_PWMCR_PRESCALER_SET(x)	FIELD_PREP(MX3_PWMCR_PRESCALER, (x) - 1)
  #define MX3_PWMCR_PRESCALER_GET(x)	(FIELD_GET(MX3_PWMCR_PRESCALER, \
  						   (x)) + 1)

  
  #define MX3_PWM_SWR_LOOP		5

  /* PWMPR register value of 0xffff has the same effect as 0xfffe */
  #define MX3_PWMPR_MAX			0xfffe

  struct pwm_imx27_chip {

  	struct clk	*clk_ipg;

  	struct clk	*clk_per;

  	struct clk	*clk_32k;

  	void __iomem	*mmio_base;

  	struct pwm_chip	chip;

  
  	/*
  	 * The driver cannot read the current duty cycle from the hardware if
  	 * the hardware is disabled. Cache the last programmed duty cycle
  	 * value to return in that case.
  	 */
  	unsigned int duty_cycle;

  };

  #define to_pwm_imx27_chip(chip)	container_of(chip, struct pwm_imx27_chip, chip)

  static int pwm_imx27_clk_prepare_enable(struct pwm_imx27_chip *imx)

  {

  	int ret;

  	if (imx->clk_32k) {
  		ret = clk_prepare_enable(imx->clk_32k);
  		if (ret)
  			goto err1;
  	}

  	ret = clk_prepare_enable(imx->clk_ipg);
  	if (ret)

  		goto err2;

  
  	ret = clk_prepare_enable(imx->clk_per);

  	if (ret)
  		goto err3;

  
  	return 0;

  err3:
  	clk_disable_unprepare(imx->clk_ipg);
  err2:
  	if (imx->clk_32k)
  		clk_disable_unprepare(imx->clk_32k);
  err1:
  	return ret;

  }

  static void pwm_imx27_clk_disable_unprepare(struct pwm_imx27_chip *imx)

  {

  	clk_disable_unprepare(imx->clk_per);
  	clk_disable_unprepare(imx->clk_ipg);

  	if (imx->clk_32k)
  		clk_disable_unprepare(imx->clk_32k);

  }

  static void pwm_imx27_get_state(struct pwm_chip *chip,
  				struct pwm_device *pwm, struct pwm_state *state)

  {

  	struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);

  	u32 period, prescaler, pwm_clk, val;

  	u64 tmp;

  	int ret;

  	ret = pwm_imx27_clk_prepare_enable(imx);

  	if (ret < 0)
  		return;

  	val = readl(imx->mmio_base + MX3_PWMCR);

  	if (val & MX3_PWMCR_EN)

  		state->enabled = true;

  	else

  		state->enabled = false;

  
  	switch (FIELD_GET(MX3_PWMCR_POUTC, val)) {
  	case MX3_PWMCR_POUTC_NORMAL:
  		state->polarity = PWM_POLARITY_NORMAL;
  		break;
  	case MX3_PWMCR_POUTC_INVERTED:
  		state->polarity = PWM_POLARITY_INVERSED;
  		break;
  	default:
  		dev_warn(chip->dev, "can't set polarity, output disconnected");
  	}
  
  	prescaler = MX3_PWMCR_PRESCALER_GET(val);
  	pwm_clk = clk_get_rate(imx->clk_per);

  	val = readl(imx->mmio_base + MX3_PWMPR);
  	period = val >= MX3_PWMPR_MAX ? MX3_PWMPR_MAX : val;
  
  	/* PWMOUT (Hz) = PWMCLK / (PWMPR + 2) */

  	tmp = NSEC_PER_SEC * (u64)(period + 2) * prescaler;
  	state->period = DIV_ROUND_UP_ULL(tmp, pwm_clk);

  	/*
  	 * PWMSAR can be read only if PWM is enabled. If the PWM is disabled,
  	 * use the cached value.
  	 */
  	if (state->enabled)

  		val = readl(imx->mmio_base + MX3_PWMSAR);

  	else
  		val = imx->duty_cycle;

  	tmp = NSEC_PER_SEC * (u64)(val) * prescaler;
  	state->duty_cycle = DIV_ROUND_UP_ULL(tmp, pwm_clk);

  	pwm_imx27_clk_disable_unprepare(imx);

  }

  static void pwm_imx27_sw_reset(struct pwm_chip *chip)

  {

  	struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);

  	struct device *dev = chip->dev;
  	int wait_count = 0;
  	u32 cr;
  
  	writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
  	do {
  		usleep_range(200, 1000);
  		cr = readl(imx->mmio_base + MX3_PWMCR);
  	} while ((cr & MX3_PWMCR_SWR) &&
  		 (wait_count++ < MX3_PWM_SWR_LOOP));
  
  	if (cr & MX3_PWMCR_SWR)
  		dev_warn(dev, "software reset timeout
  ");
  }

  static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip,
  				     struct pwm_device *pwm)

  {

  	struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);

  	struct device *dev = chip->dev;
  	unsigned int period_ms;
  	int fifoav;
  	u32 sr;

  	sr = readl(imx->mmio_base + MX3_PWMSR);

  	fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);

  	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {

  		period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm),

  					 NSEC_PER_MSEC);
  		msleep(period_ms);

  		sr = readl(imx->mmio_base + MX3_PWMSR);

  		if (fifoav == FIELD_GET(MX3_PWMSR_FIFOAV, sr))

  			dev_warn(dev, "there is no free FIFO slot
  ");
  	}

  }

  static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,

  			   const struct pwm_state *state)

  {

  	unsigned long period_cycles, duty_cycles, prescale;

  	struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);

  	struct pwm_state cstate;
  	unsigned long long c;

  	unsigned long long clkrate;

  	int ret;

  	u32 cr;

  
  	pwm_get_state(pwm, &cstate);

  	clkrate = clk_get_rate(imx->clk_per);
  	c = clkrate * state->period;

  	do_div(c, NSEC_PER_SEC);

  	period_cycles = c;
  
  	prescale = period_cycles / 0x10000 + 1;
  
  	period_cycles /= prescale;

  	c = clkrate * state->duty_cycle;

  	do_div(c, NSEC_PER_SEC);

  	duty_cycles = c;

  	duty_cycles /= prescale;

  
  	/*
  	 * according to imx pwm RM, the real period value should be PERIOD
  	 * value in PWMPR plus 2.
  	 */
  	if (period_cycles > 2)
  		period_cycles -= 2;
  	else
  		period_cycles = 0;
  
  	/*
  	 * Wait for a free FIFO slot if the PWM is already enabled, and flush
  	 * the FIFO if the PWM was disabled and is about to be enabled.
  	 */
  	if (cstate.enabled) {
  		pwm_imx27_wait_fifo_slot(chip, pwm);
  	} else {

  		ret = pwm_imx27_clk_prepare_enable(imx);

  		if (ret)
  			return ret;
  
  		pwm_imx27_sw_reset(chip);

  	}

  	writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
  	writel(period_cycles, imx->mmio_base + MX3_PWMPR);
  
  	/*
  	 * Store the duty cycle for future reference in cases where the
  	 * MX3_PWMSAR register can't be read (i.e. when the PWM is disabled).
  	 */
  	imx->duty_cycle = duty_cycles;
  
  	cr = MX3_PWMCR_PRESCALER_SET(prescale) |
  	     MX3_PWMCR_STOPEN | MX3_PWMCR_DOZEN | MX3_PWMCR_WAITEN |
  	     FIELD_PREP(MX3_PWMCR_CLKSRC, MX3_PWMCR_CLKSRC_IPG_HIGH) |
  	     MX3_PWMCR_DBGEN;
  
  	if (state->polarity == PWM_POLARITY_INVERSED)
  		cr |= FIELD_PREP(MX3_PWMCR_POUTC,
  				MX3_PWMCR_POUTC_INVERTED);
  
  	if (state->enabled)
  		cr |= MX3_PWMCR_EN;
  
  	writel(cr, imx->mmio_base + MX3_PWMCR);

  	if (!state->enabled)

  		pwm_imx27_clk_disable_unprepare(imx);

  	return 0;

  }

  static const struct pwm_ops pwm_imx27_ops = {
  	.apply = pwm_imx27_apply,
  	.get_state = pwm_imx27_get_state,

  	.owner = THIS_MODULE,
  };

  static const struct of_device_id pwm_imx27_dt_ids[] = {
  	{ .compatible = "fsl,imx27-pwm", },

  	{ /* sentinel */ }
  };

  MODULE_DEVICE_TABLE(of, pwm_imx27_dt_ids);

  static int pwm_imx27_probe(struct platform_device *pdev)

  {

  	struct pwm_imx27_chip *imx;

  	int ret;
  	u32 pwmcr;

  	imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);

  	if (imx == NULL)

  		return -ENOMEM;

  	platform_set_drvdata(pdev, imx);

  	imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
  	if (IS_ERR(imx->clk_ipg)) {

  		int ret = PTR_ERR(imx->clk_ipg);
  
  		if (ret != -EPROBE_DEFER)
  			dev_err(&pdev->dev,
  				"getting ipg clock failed with %d
  ",
  				ret);
  		return ret;

  	}

  	imx->clk_per = devm_clk_get(&pdev->dev, "per");
  	if (IS_ERR(imx->clk_per)) {

  		int ret = PTR_ERR(imx->clk_per);
  
  		if (ret != -EPROBE_DEFER)
  			dev_err(&pdev->dev,
  				"failed to get peripheral clock: %d
  ",
  				ret);
  
  		return ret;

  	}

  	imx->clk_32k = devm_clk_get_optional(&pdev->dev, "32k");
  	if (IS_ERR(imx->clk_32k)) {
  		dev_err(&pdev->dev, "getting 32k clock failed with %ld
  ",
  				PTR_ERR(imx->clk_32k));
  		return PTR_ERR(imx->clk_32k);
  	}

  	imx->chip.ops = &pwm_imx27_ops;

  	imx->chip.dev = &pdev->dev;
  	imx->chip.base = -1;
  	imx->chip.npwm = 1;

  	imx->chip.of_xlate = of_pwm_xlate_with_flags;
  	imx->chip.of_pwm_n_cells = 3;

  	imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);

  	if (IS_ERR(imx->mmio_base))
  		return PTR_ERR(imx->mmio_base);

  	ret = pwm_imx27_clk_prepare_enable(imx);
  	if (ret)
  		return ret;
  
  	/* keep clks on if pwm is running */
  	pwmcr = readl(imx->mmio_base + MX3_PWMCR);
  	if (!(pwmcr & MX3_PWMCR_EN))
  		pwm_imx27_clk_disable_unprepare(imx);

  	return pwmchip_add(&imx->chip);

  }

  static int pwm_imx27_remove(struct platform_device *pdev)

  {

  	struct pwm_imx27_chip *imx;

  	imx = platform_get_drvdata(pdev);

  	return pwmchip_remove(&imx->chip);

  }

  static struct platform_driver imx_pwm_driver = {

  	.driver = {
  		.name = "pwm-imx27",
  		.of_match_table = pwm_imx27_dt_ids,

  	},

  	.probe = pwm_imx27_probe,
  	.remove = pwm_imx27_remove,

  };

  module_platform_driver(imx_pwm_driver);

  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");