/*
   * MediaTek display pulse-width-modulation controller driver.
   * Copyright (c) 2015 MediaTek Inc.
   * Author: YH Huang <yh.huang@mediatek.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * 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/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/pwm.h>
  #include <linux/slab.h>
  
  #define DISP_PWM_EN		0x00
  #define PWM_ENABLE_MASK		BIT(0)
  
  #define DISP_PWM_COMMIT		0x08
  #define PWM_COMMIT_MASK		BIT(0)
  
  #define DISP_PWM_CON_0		0x10
  #define PWM_CLKDIV_SHIFT	16
  #define PWM_CLKDIV_MAX		0x3ff
  #define PWM_CLKDIV_MASK		(PWM_CLKDIV_MAX << PWM_CLKDIV_SHIFT)
  
  #define DISP_PWM_CON_1		0x14
  #define PWM_PERIOD_BIT_WIDTH	12
  #define PWM_PERIOD_MASK		((1 << PWM_PERIOD_BIT_WIDTH) - 1)
  
  #define PWM_HIGH_WIDTH_SHIFT	16
  #define PWM_HIGH_WIDTH_MASK	(0x1fff << PWM_HIGH_WIDTH_SHIFT)
  
  struct mtk_disp_pwm {
  	struct pwm_chip chip;
  	struct clk *clk_main;
  	struct clk *clk_mm;
  	void __iomem *base;
  };
  
  static inline struct mtk_disp_pwm *to_mtk_disp_pwm(struct pwm_chip *chip)
  {
  	return container_of(chip, struct mtk_disp_pwm, chip);
  }
  
  static void mtk_disp_pwm_update_bits(struct mtk_disp_pwm *mdp, u32 offset,
  				     u32 mask, u32 data)
  {
  	void __iomem *address = mdp->base + offset;
  	u32 value;
  
  	value = readl(address);
  	value &= ~mask;
  	value |= data;
  	writel(value, address);
  }
  
  static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  			       int duty_ns, int period_ns)
  {
  	struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
  	u32 clk_div, period, high_width, value;
  	u64 div, rate;
  	int err;
  
  	/*
  	 * Find period, high_width and clk_div to suit duty_ns and period_ns.
  	 * Calculate proper div value to keep period value in the bound.
  	 *
  	 * period_ns = 10^9 * (clk_div + 1) * (period + 1) / PWM_CLK_RATE
  	 * duty_ns = 10^9 * (clk_div + 1) * high_width / PWM_CLK_RATE
  	 *
  	 * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
  	 * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1))
  	 */
  	rate = clk_get_rate(mdp->clk_main);
  	clk_div = div_u64(rate * period_ns, NSEC_PER_SEC) >>
  			  PWM_PERIOD_BIT_WIDTH;
  	if (clk_div > PWM_CLKDIV_MAX)
  		return -EINVAL;
  
  	div = NSEC_PER_SEC * (clk_div + 1);
  	period = div64_u64(rate * period_ns, div);
  	if (period > 0)
  		period--;
  
  	high_width = div64_u64(rate * duty_ns, div);
  	value = period | (high_width << PWM_HIGH_WIDTH_SHIFT);
  
  	err = clk_enable(mdp->clk_main);
  	if (err < 0)
  		return err;
  
  	err = clk_enable(mdp->clk_mm);
  	if (err < 0) {
  		clk_disable(mdp->clk_main);
  		return err;
  	}
  
  	mtk_disp_pwm_update_bits(mdp, DISP_PWM_CON_0, PWM_CLKDIV_MASK,
  				 clk_div << PWM_CLKDIV_SHIFT);
  	mtk_disp_pwm_update_bits(mdp, DISP_PWM_CON_1,
  				 PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK, value);
  	mtk_disp_pwm_update_bits(mdp, DISP_PWM_COMMIT, PWM_COMMIT_MASK, 1);
  	mtk_disp_pwm_update_bits(mdp, DISP_PWM_COMMIT, PWM_COMMIT_MASK, 0);
  
  	clk_disable(mdp->clk_mm);
  	clk_disable(mdp->clk_main);
  
  	return 0;
  }
  
  static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
  	int err;
  
  	err = clk_enable(mdp->clk_main);
  	if (err < 0)
  		return err;
  
  	err = clk_enable(mdp->clk_mm);
  	if (err < 0) {
  		clk_disable(mdp->clk_main);
  		return err;
  	}
  
  	mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, PWM_ENABLE_MASK, 1);
  
  	return 0;
  }
  
  static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
  
  	mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, PWM_ENABLE_MASK, 0);
  
  	clk_disable(mdp->clk_mm);
  	clk_disable(mdp->clk_main);
  }
  
  static const struct pwm_ops mtk_disp_pwm_ops = {
  	.config = mtk_disp_pwm_config,
  	.enable = mtk_disp_pwm_enable,
  	.disable = mtk_disp_pwm_disable,
  	.owner = THIS_MODULE,
  };
  
  static int mtk_disp_pwm_probe(struct platform_device *pdev)
  {
  	struct mtk_disp_pwm *mdp;
  	struct resource *r;
  	int ret;
  
  	mdp = devm_kzalloc(&pdev->dev, sizeof(*mdp), GFP_KERNEL);
  	if (!mdp)
  		return -ENOMEM;
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	mdp->base = devm_ioremap_resource(&pdev->dev, r);
  	if (IS_ERR(mdp->base))
  		return PTR_ERR(mdp->base);
  
  	mdp->clk_main = devm_clk_get(&pdev->dev, "main");
  	if (IS_ERR(mdp->clk_main))
  		return PTR_ERR(mdp->clk_main);
  
  	mdp->clk_mm = devm_clk_get(&pdev->dev, "mm");
  	if (IS_ERR(mdp->clk_mm))
  		return PTR_ERR(mdp->clk_mm);
  
  	ret = clk_prepare(mdp->clk_main);
  	if (ret < 0)
  		return ret;
  
  	ret = clk_prepare(mdp->clk_mm);
  	if (ret < 0)
  		goto disable_clk_main;
  
  	mdp->chip.dev = &pdev->dev;
  	mdp->chip.ops = &mtk_disp_pwm_ops;
  	mdp->chip.base = -1;
  	mdp->chip.npwm = 1;
  
  	ret = pwmchip_add(&mdp->chip);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "pwmchip_add() failed: %d
  ", ret);
  		goto disable_clk_mm;
  	}
  
  	platform_set_drvdata(pdev, mdp);
  
  	return 0;
  
  disable_clk_mm:
  	clk_unprepare(mdp->clk_mm);
  disable_clk_main:
  	clk_unprepare(mdp->clk_main);
  	return ret;
  }
  
  static int mtk_disp_pwm_remove(struct platform_device *pdev)
  {
  	struct mtk_disp_pwm *mdp = platform_get_drvdata(pdev);
  	int ret;
  
  	ret = pwmchip_remove(&mdp->chip);
  	clk_unprepare(mdp->clk_mm);
  	clk_unprepare(mdp->clk_main);
  
  	return ret;
  }
  
  static const struct of_device_id mtk_disp_pwm_of_match[] = {
  	{ .compatible = "mediatek,mt8173-disp-pwm" },
  	{ .compatible = "mediatek,mt6595-disp-pwm" },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);
  
  static struct platform_driver mtk_disp_pwm_driver = {
  	.driver = {
  		.name = "mediatek-disp-pwm",
  		.of_match_table = mtk_disp_pwm_of_match,
  	},
  	.probe = mtk_disp_pwm_probe,
  	.remove = mtk_disp_pwm_remove,
  };
  module_platform_driver(mtk_disp_pwm_driver);
  
  MODULE_AUTHOR("YH Huang <yh.huang@mediatek.com>");
  MODULE_DESCRIPTION("MediaTek SoC display PWM driver");
  MODULE_LICENSE("GPL v2");