/*
 * 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");