/*
 * GPIO driver for NXP LPC18xx/43xx.
 *
 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.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/clk.h>
#include <linux/gpio/driver.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>

/* LPC18xx GPIO register offsets */
#define LPC18XX_REG_DIR(n)	(0x2000 + n * sizeof(u32))

#define LPC18XX_MAX_PORTS	8
#define LPC18XX_PINS_PER_PORT	32

struct lpc18xx_gpio_chip {
	struct gpio_chip gpio;
	void __iomem *base;
	struct clk *clk;
	spinlock_t lock;
};

static inline struct lpc18xx_gpio_chip *to_lpc18xx_gpio(struct gpio_chip *chip)
{
	return container_of(chip, struct lpc18xx_gpio_chip, gpio);
}

static void lpc18xx_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
	struct lpc18xx_gpio_chip *gc = to_lpc18xx_gpio(chip);
	writeb(value ? 1 : 0, gc->base + offset);
}

static int lpc18xx_gpio_get(struct gpio_chip *chip, unsigned offset)
{
	struct lpc18xx_gpio_chip *gc = to_lpc18xx_gpio(chip);
	return !!readb(gc->base + offset);
}

static int lpc18xx_gpio_direction(struct gpio_chip *chip, unsigned offset,
				  bool out)
{
	struct lpc18xx_gpio_chip *gc = to_lpc18xx_gpio(chip);
	unsigned long flags;
	u32 port, pin, dir;

	port = offset / LPC18XX_PINS_PER_PORT;
	pin  = offset % LPC18XX_PINS_PER_PORT;

	spin_lock_irqsave(&gc->lock, flags);
	dir = readl(gc->base + LPC18XX_REG_DIR(port));
	if (out)
		dir |= BIT(pin);
	else
		dir &= ~BIT(pin);
	writel(dir, gc->base + LPC18XX_REG_DIR(port));
	spin_unlock_irqrestore(&gc->lock, flags);

	return 0;
}

static int lpc18xx_gpio_direction_input(struct gpio_chip *chip,
					unsigned offset)
{
	return lpc18xx_gpio_direction(chip, offset, false);
}

static int lpc18xx_gpio_direction_output(struct gpio_chip *chip,
					 unsigned offset, int value)
{
	lpc18xx_gpio_set(chip, offset, value);
	return lpc18xx_gpio_direction(chip, offset, true);
}

static struct gpio_chip lpc18xx_chip = {
	.label			= "lpc18xx/43xx-gpio",
	.request		= gpiochip_generic_request,
	.free			= gpiochip_generic_free,
	.direction_input	= lpc18xx_gpio_direction_input,
	.direction_output	= lpc18xx_gpio_direction_output,
	.set			= lpc18xx_gpio_set,
	.get			= lpc18xx_gpio_get,
	.ngpio			= LPC18XX_MAX_PORTS * LPC18XX_PINS_PER_PORT,
	.owner			= THIS_MODULE,
};

static int lpc18xx_gpio_probe(struct platform_device *pdev)
{
	struct lpc18xx_gpio_chip *gc;
	struct resource *res;
	int ret;

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

	gc->gpio = lpc18xx_chip;
	platform_set_drvdata(pdev, gc);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	gc->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(gc->base))
		return PTR_ERR(gc->base);

	gc->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(gc->clk)) {
		dev_err(&pdev->dev, "input clock not found\n");
		return PTR_ERR(gc->clk);
	}

	ret = clk_prepare_enable(gc->clk);
	if (ret) {
		dev_err(&pdev->dev, "unable to enable clock\n");
		return ret;
	}

	spin_lock_init(&gc->lock);

	gc->gpio.dev = &pdev->dev;

	ret = gpiochip_add(&gc->gpio);
	if (ret) {
		dev_err(&pdev->dev, "failed to add gpio chip\n");
		clk_disable_unprepare(gc->clk);
		return ret;
	}

	return 0;
}

static int lpc18xx_gpio_remove(struct platform_device *pdev)
{
	struct lpc18xx_gpio_chip *gc = platform_get_drvdata(pdev);

	gpiochip_remove(&gc->gpio);
	clk_disable_unprepare(gc->clk);

	return 0;
}

static const struct of_device_id lpc18xx_gpio_match[] = {
	{ .compatible = "nxp,lpc1850-gpio" },
	{ }
};
MODULE_DEVICE_TABLE(of, lpc18xx_gpio_match);

static struct platform_driver lpc18xx_gpio_driver = {
	.probe	= lpc18xx_gpio_probe,
	.remove	= lpc18xx_gpio_remove,
	.driver	= {
		.name		= "lpc18xx-gpio",
		.of_match_table	= lpc18xx_gpio_match,
	},
};
module_platform_driver(lpc18xx_gpio_driver);

MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
MODULE_DESCRIPTION("GPIO driver for LPC18xx/43xx");
MODULE_LICENSE("GPL v2");