/*
   * Copyright 2012 Freescale Semiconductor, Inc.
   *
   * The code contained herein is licensed under the GNU General Public
   * License. You may obtain a copy of the GNU General Public License
   * Version 2 or later at the following locations:
   *
   * http://www.opensource.org/licenses/gpl-license.html
   * http://www.gnu.org/copyleft/gpl.html
   */
  
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/platform_device.h>
  #include <linux/pwm.h>
  #include <linux/slab.h>

  #include <linux/stmp_device.h>

  
  #define SET	0x4
  #define CLR	0x8
  #define TOG	0xc
  
  #define PWM_CTRL		0x0
  #define PWM_ACTIVE0		0x10
  #define PWM_PERIOD0		0x20
  #define  PERIOD_PERIOD(p)	((p) & 0xffff)
  #define  PERIOD_PERIOD_MAX	0x10000
  #define  PERIOD_ACTIVE_HIGH	(3 << 16)
  #define  PERIOD_INACTIVE_LOW	(2 << 18)
  #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
  #define  PERIOD_CDIV_MAX	8

  static const unsigned int cdiv[PERIOD_CDIV_MAX] = {
  	1, 2, 4, 8, 16, 64, 256, 1024
  };

  struct mxs_pwm_chip {
  	struct pwm_chip chip;

  	struct clk *clk;
  	void __iomem *base;
  };
  
  #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
  
  static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  			  int duty_ns, int period_ns)
  {
  	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
  	int ret, div = 0;
  	unsigned int period_cycles, duty_cycles;
  	unsigned long rate;
  	unsigned long long c;
  
  	rate = clk_get_rate(mxs->clk);
  	while (1) {

  		c = rate / cdiv[div];

  		c = c * period_ns;
  		do_div(c, 1000000000);
  		if (c < PERIOD_PERIOD_MAX)
  			break;
  		div++;

  		if (div >= PERIOD_CDIV_MAX)

  			return -EINVAL;
  	}
  
  	period_cycles = c;
  	c *= duty_ns;
  	do_div(c, period_ns);
  	duty_cycles = c;
  
  	/*
  	 * If the PWM channel is disabled, make sure to turn on the clock
  	 * before writing the register. Otherwise, keep it enabled.
  	 */

  	if (!pwm_is_enabled(pwm)) {

  		ret = clk_prepare_enable(mxs->clk);
  		if (ret)
  			return ret;
  	}
  
  	writel(duty_cycles << 16,
  			mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
  	writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
  	       PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
  			mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
  
  	/*
  	 * If the PWM is not enabled, turn the clock off again to save power.
  	 */

  	if (!pwm_is_enabled(pwm))

  		clk_disable_unprepare(mxs->clk);
  
  	return 0;
  }
  
  static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
  	int ret;
  
  	ret = clk_prepare_enable(mxs->clk);
  	if (ret)
  		return ret;
  
  	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
  
  	return 0;
  }
  
  static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
  
  	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
  
  	clk_disable_unprepare(mxs->clk);
  }
  
  static const struct pwm_ops mxs_pwm_ops = {
  	.config = mxs_pwm_config,
  	.enable = mxs_pwm_enable,
  	.disable = mxs_pwm_disable,
  	.owner = THIS_MODULE,
  };
  
  static int mxs_pwm_probe(struct platform_device *pdev)
  {
  	struct device_node *np = pdev->dev.of_node;
  	struct mxs_pwm_chip *mxs;

  	struct resource *res;

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

  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

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

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

  
  	mxs->chip.dev = &pdev->dev;
  	mxs->chip.ops = &mxs_pwm_ops;
  	mxs->chip.base = -1;

  	ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "failed to get pwm number: %d
  ", ret);

  		return ret;

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

  		return ret;

  	}

  	platform_set_drvdata(pdev, mxs);

  	ret = stmp_reset_block(mxs->base);
  	if (ret)
  		goto pwm_remove;

  
  	return 0;

  
  pwm_remove:
  	pwmchip_remove(&mxs->chip);
  	return ret;

  }

  static int mxs_pwm_remove(struct platform_device *pdev)

  {
  	struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);

  	return pwmchip_remove(&mxs->chip);

  }

  static const struct of_device_id mxs_pwm_dt_ids[] = {

  	{ .compatible = "fsl,imx23-pwm", },

  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
  
  static struct platform_driver mxs_pwm_driver = {
  	.driver = {
  		.name = "mxs-pwm",

  		.of_match_table = mxs_pwm_dt_ids,

  	},
  	.probe = mxs_pwm_probe,

  	.remove = mxs_pwm_remove,

  };
  module_platform_driver(mxs_pwm_driver);
  
  MODULE_ALIAS("platform:mxs-pwm");
  MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
  MODULE_DESCRIPTION("Freescale MXS PWM Driver");
  MODULE_LICENSE("GPL v2");