text: /*
   * Cirrus Logic CLPS711X PWM driver
   *
   * Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
   *
   * 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/io.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/pwm.h>
  
  struct clps711x_chip {
  	struct pwm_chip chip;
  	void __iomem *pmpcon;
  	struct clk *clk;
  	spinlock_t lock;
  };
  
  static inline struct clps711x_chip *to_clps711x_chip(struct pwm_chip *chip)
  {
  	return container_of(chip, struct clps711x_chip, chip);
  }
  
  static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
  {
  	/* PWM0 - bits 4..7, PWM1 - bits 8..11 */
  	u32 shift = (n + 1) * 4;
  	unsigned long flags;
  	u32 tmp;
  
  	spin_lock_irqsave(&priv->lock, flags);
  
  	tmp = readl(priv->pmpcon);
  	tmp &= ~(0xf << shift);
  	tmp |= v << shift;
  	writel(tmp, priv->pmpcon);
  
  	spin_unlock_irqrestore(&priv->lock, flags);
  }
  
  static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
  {
  	/* Duty cycle 0..15 max */
  	return DIV_ROUND_CLOSEST(v * 0xf, pwm_get_period(pwm));
  }
  
  static int clps711x_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct clps711x_chip *priv = to_clps711x_chip(chip);
  	unsigned int freq = clk_get_rate(priv->clk);
  
  	if (!freq)
  		return -EINVAL;
  
  	/* Store constant period value */
  	pwm_set_period(pwm, DIV_ROUND_CLOSEST(NSEC_PER_SEC, freq));
  
  	return 0;
  }
  
  static int clps711x_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  			       int duty_ns, int period_ns)
  {
  	struct clps711x_chip *priv = to_clps711x_chip(chip);
  	unsigned int duty;
  
  	if (period_ns != pwm_get_period(pwm))
  		return -EINVAL;
  
  	duty = clps711x_get_duty(pwm, duty_ns);
  	clps711x_pwm_update_val(priv, pwm->hwpwm, duty);
  
  	return 0;
  }
  
  static int clps711x_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct clps711x_chip *priv = to_clps711x_chip(chip);
  	unsigned int duty;
  
  	duty = clps711x_get_duty(pwm, pwm_get_duty_cycle(pwm));
  	clps711x_pwm_update_val(priv, pwm->hwpwm, duty);
  
  	return 0;
  }
  
  static void clps711x_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct clps711x_chip *priv = to_clps711x_chip(chip);
  
  	clps711x_pwm_update_val(priv, pwm->hwpwm, 0);
  }
  
  static const struct pwm_ops clps711x_pwm_ops = {
  	.request = clps711x_pwm_request,
  	.config = clps711x_pwm_config,
  	.enable = clps711x_pwm_enable,
  	.disable = clps711x_pwm_disable,
  	.owner = THIS_MODULE,
  };
  
  static struct pwm_device *clps711x_pwm_xlate(struct pwm_chip *chip,
  					     const struct of_phandle_args *args)
  {
  	if (args->args[0] >= chip->npwm)
  		return ERR_PTR(-EINVAL);
  
  	return pwm_request_from_chip(chip, args->args[0], NULL);
  }
  
  static int clps711x_pwm_probe(struct platform_device *pdev)
  {
  	struct clps711x_chip *priv;
  	struct resource *res;
  
  	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	priv->pmpcon = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(priv->pmpcon))
  		return PTR_ERR(priv->pmpcon);
  
  	priv->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(priv->clk))
  		return PTR_ERR(priv->clk);
  
  	priv->chip.ops = &clps711x_pwm_ops;
  	priv->chip.dev = &pdev->dev;
  	priv->chip.base = -1;
  	priv->chip.npwm = 2;
  	priv->chip.of_xlate = clps711x_pwm_xlate;
  	priv->chip.of_pwm_n_cells = 1;
  
  	spin_lock_init(&priv->lock);
  
  	platform_set_drvdata(pdev, priv);
  
  	return pwmchip_add(&priv->chip);
  }
  
  static int clps711x_pwm_remove(struct platform_device *pdev)
  {
  	struct clps711x_chip *priv = platform_get_drvdata(pdev);
  
  	return pwmchip_remove(&priv->chip);
  }
  
  static const struct of_device_id __maybe_unused clps711x_pwm_dt_ids[] = {
  	{ .compatible = "cirrus,clps711x-pwm", },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, clps711x_pwm_dt_ids);
  
  static struct platform_driver clps711x_pwm_driver = {
  	.driver = {
  		.name = "clps711x-pwm",
  		.of_match_table = of_match_ptr(clps711x_pwm_dt_ids),
  	},
  	.probe = clps711x_pwm_probe,
  	.remove = clps711x_pwm_remove,
  };
  module_platform_driver(clps711x_pwm_driver);
  
  MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
  MODULE_DESCRIPTION("Cirrus Logic CLPS711X PWM driver");
  MODULE_LICENSE("GPL");
  