text: /*
   * Intel Low Power Subsystem PWM controller driver
   *
   * Copyright (C) 2014, Intel Corporation
   * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
   * Author: Chew Kean Ho <kean.ho.chew@intel.com>
   * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
   * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
   * Author: Alan Cox <alan@linux.intel.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.
   */
  
  #include <linux/acpi.h>
  #include <linux/clk.h>
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/pwm.h>
  #include <linux/platform_device.h>
  #include <linux/pci.h>
  
  static int pci_drv, plat_drv;	/* So we know which drivers registered */
  
  #define PWM				0x00000000
  #define PWM_ENABLE			BIT(31)
  #define PWM_SW_UPDATE			BIT(30)
  #define PWM_BASE_UNIT_SHIFT		8
  #define PWM_BASE_UNIT_MASK		0x00ffff00
  #define PWM_ON_TIME_DIV_MASK		0x000000ff
  #define PWM_DIVISION_CORRECTION		0x2
  #define PWM_LIMIT			(0x8000 + PWM_DIVISION_CORRECTION)
  #define NSECS_PER_SEC			1000000000UL
  
  struct pwm_lpss_chip {
  	struct pwm_chip chip;
  	void __iomem *regs;
  	struct clk *clk;
  	unsigned long clk_rate;
  };
  
  struct pwm_lpss_boardinfo {
  	unsigned long clk_rate;
  };
  
  /* BayTrail */
  static const struct pwm_lpss_boardinfo byt_info = {
  	25000000
  };
  
  static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
  {
  	return container_of(chip, struct pwm_lpss_chip, chip);
  }
  
  static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
  			   int duty_ns, int period_ns)
  {
  	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  	u8 on_time_div;
  	unsigned long c;
  	unsigned long long base_unit, freq = NSECS_PER_SEC;
  	u32 ctrl;
  
  	do_div(freq, period_ns);
  
  	/* The equation is: base_unit = ((freq / c) * 65536) + correction */
  	base_unit = freq * 65536;
  
  	c = lpwm->clk_rate;
  	if (!c)
  		return -EINVAL;
  
  	do_div(base_unit, c);
  	base_unit += PWM_DIVISION_CORRECTION;
  	if (base_unit > PWM_LIMIT)
  		return -EINVAL;
  
  	if (duty_ns <= 0)
  		duty_ns = 1;
  	on_time_div = 255 - (255 * duty_ns / period_ns);
  
  	ctrl = readl(lpwm->regs + PWM);
  	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
  	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
  	ctrl |= on_time_div;
  	/* request PWM to update on next cycle */
  	ctrl |= PWM_SW_UPDATE;
  	writel(ctrl, lpwm->regs + PWM);
  
  	return 0;
  }
  
  static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  	u32 ctrl;
  	int ret;
  
  	ret = clk_prepare_enable(lpwm->clk);
  	if (ret)
  		return ret;
  
  	ctrl = readl(lpwm->regs + PWM);
  	writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
  
  	return 0;
  }
  
  static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  {
  	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
  	u32 ctrl;
  
  	ctrl = readl(lpwm->regs + PWM);
  	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
  
  	clk_disable_unprepare(lpwm->clk);
  }
  
  static const struct pwm_ops pwm_lpss_ops = {
  	.config = pwm_lpss_config,
  	.enable = pwm_lpss_enable,
  	.disable = pwm_lpss_disable,
  	.owner = THIS_MODULE,
  };
  
  static struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev,
  					    struct resource *r,
  					    const struct pwm_lpss_boardinfo *info)
  {
  	struct pwm_lpss_chip *lpwm;
  	int ret;
  
  	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
  	if (!lpwm)
  		return ERR_PTR(-ENOMEM);
  
  	lpwm->regs = devm_ioremap_resource(dev, r);
  	if (IS_ERR(lpwm->regs))
  		return ERR_CAST(lpwm->regs);
  
  	if (info) {
  		lpwm->clk_rate = info->clk_rate;
  	} else {
  		lpwm->clk = devm_clk_get(dev, NULL);
  		if (IS_ERR(lpwm->clk)) {
  			dev_err(dev, "failed to get PWM clock\n");
  			return ERR_CAST(lpwm->clk);
  		}
  		lpwm->clk_rate = clk_get_rate(lpwm->clk);
  	}
  
  	lpwm->chip.dev = dev;
  	lpwm->chip.ops = &pwm_lpss_ops;
  	lpwm->chip.base = -1;
  	lpwm->chip.npwm = 1;
  
  	ret = pwmchip_add(&lpwm->chip);
  	if (ret) {
  		dev_err(dev, "failed to add PWM chip: %d\n", ret);
  		return ERR_PTR(ret);
  	}
  
  	return lpwm;
  }
  
  static int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
  {
  	u32 ctrl;
  
  	ctrl = readl(lpwm->regs + PWM);
  	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
  
  	return pwmchip_remove(&lpwm->chip);
  }
  
  static int pwm_lpss_probe_pci(struct pci_dev *pdev,
  			      const struct pci_device_id *id)
  {
  	const struct pwm_lpss_boardinfo *info;
  	struct pwm_lpss_chip *lpwm;
  	int err;
  
  	err = pci_enable_device(pdev);
  	if (err < 0)
  		return err;
  
  	info = (struct pwm_lpss_boardinfo *)id->driver_data;
  	lpwm = pwm_lpss_probe(&pdev->dev, &pdev->resource[0], info);
  	if (IS_ERR(lpwm))
  		return PTR_ERR(lpwm);
  
  	pci_set_drvdata(pdev, lpwm);
  	return 0;
  }
  
  static void pwm_lpss_remove_pci(struct pci_dev *pdev)
  {
  	struct pwm_lpss_chip *lpwm = pci_get_drvdata(pdev);
  
  	pwm_lpss_remove(lpwm);
  	pci_disable_device(pdev);
  }
  
  static struct pci_device_id pwm_lpss_pci_ids[] = {
  	{ PCI_VDEVICE(INTEL, 0x0f08), (unsigned long)&byt_info},
  	{ PCI_VDEVICE(INTEL, 0x0f09), (unsigned long)&byt_info},
  	{ },
  };
  MODULE_DEVICE_TABLE(pci, pwm_lpss_pci_ids);
  
  static struct pci_driver pwm_lpss_driver_pci = {
  	.name = "pwm-lpss",
  	.id_table = pwm_lpss_pci_ids,
  	.probe = pwm_lpss_probe_pci,
  	.remove = pwm_lpss_remove_pci,
  };
  
  static int pwm_lpss_probe_platform(struct platform_device *pdev)
  {
  	struct pwm_lpss_chip *lpwm;
  	struct resource *r;
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  
  	lpwm = pwm_lpss_probe(&pdev->dev, r, NULL);
  	if (IS_ERR(lpwm))
  		return PTR_ERR(lpwm);
  
  	platform_set_drvdata(pdev, lpwm);
  	return 0;
  }
  
  static int pwm_lpss_remove_platform(struct platform_device *pdev)
  {
  	struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
  
  	return pwm_lpss_remove(lpwm);
  }
  
  static const struct acpi_device_id pwm_lpss_acpi_match[] = {
  	{ "80860F09", 0 },
  	{ },
  };
  MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
  
  static struct platform_driver pwm_lpss_driver_platform = {
  	.driver = {
  		.name = "pwm-lpss",
  		.acpi_match_table = pwm_lpss_acpi_match,
  	},
  	.probe = pwm_lpss_probe_platform,
  	.remove = pwm_lpss_remove_platform,
  };
  
  static int __init pwm_init(void)
  {
  	pci_drv = pci_register_driver(&pwm_lpss_driver_pci);
  	plat_drv = platform_driver_register(&pwm_lpss_driver_platform);
  	if (pci_drv && plat_drv)
  		return pci_drv;
  
  	return 0;
  }
  module_init(pwm_init);
  
  static void __exit pwm_exit(void)
  {
  	if (!pci_drv)
  		pci_unregister_driver(&pwm_lpss_driver_pci);
  	if (!plat_drv)
  		platform_driver_unregister(&pwm_lpss_driver_platform);
  }
  module_exit(pwm_exit);
  
  MODULE_DESCRIPTION("PWM driver for Intel LPSS");
  MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS("platform:pwm-lpss");
  