/*
 *  linux/drivers/gpio/gpio-mb86s7x.c
 *
 *  Copyright (C) 2015 Fujitsu Semiconductor Limited
 *  Copyright (C) 2015 Linaro Ltd.
 *
 *  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, version 2 of the License.
 *
 *  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/io.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/of_device.h>
#include <linux/gpio/driver.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/slab.h>

/*
 * Only first 8bits of a register correspond to each pin,
 * so there are 4 registers for 32 pins.
 */
#define PDR(x)	(0x0 + x / 8 * 4)
#define DDR(x)	(0x10 + x / 8 * 4)
#define PFR(x)	(0x20 + x / 8 * 4)

#define OFFSET(x)	BIT((x) % 8)

struct mb86s70_gpio_chip {
	struct gpio_chip gc;
	void __iomem *base;
	struct clk *clk;
	spinlock_t lock;
};

static int mb86s70_gpio_request(struct gpio_chip *gc, unsigned gpio)
{
	struct mb86s70_gpio_chip *gchip = gpiochip_get_data(gc);
	unsigned long flags;
	u32 val;

	spin_lock_irqsave(&gchip->lock, flags);

	val = readl(gchip->base + PFR(gpio));
	if (!(val & OFFSET(gpio))) {
		spin_unlock_irqrestore(&gchip->lock, flags);
		return -EINVAL;
	}

	val &= ~OFFSET(gpio);
	writel(val, gchip->base + PFR(gpio));

	spin_unlock_irqrestore(&gchip->lock, flags);

	return 0;
}

static void mb86s70_gpio_free(struct gpio_chip *gc, unsigned gpio)
{
	struct mb86s70_gpio_chip *gchip = gpiochip_get_data(gc);
	unsigned long flags;
	u32 val;

	spin_lock_irqsave(&gchip->lock, flags);

	val = readl(gchip->base + PFR(gpio));
	val |= OFFSET(gpio);
	writel(val, gchip->base + PFR(gpio));

	spin_unlock_irqrestore(&gchip->lock, flags);
}

static int mb86s70_gpio_direction_input(struct gpio_chip *gc, unsigned gpio)
{
	struct mb86s70_gpio_chip *gchip = gpiochip_get_data(gc);
	unsigned long flags;
	unsigned char val;

	spin_lock_irqsave(&gchip->lock, flags);

	val = readl(gchip->base + DDR(gpio));
	val &= ~OFFSET(gpio);
	writel(val, gchip->base + DDR(gpio));

	spin_unlock_irqrestore(&gchip->lock, flags);

	return 0;
}

static int mb86s70_gpio_direction_output(struct gpio_chip *gc,
					 unsigned gpio, int value)
{
	struct mb86s70_gpio_chip *gchip = gpiochip_get_data(gc);
	unsigned long flags;
	unsigned char val;

	spin_lock_irqsave(&gchip->lock, flags);

	val = readl(gchip->base + PDR(gpio));
	if (value)
		val |= OFFSET(gpio);
	else
		val &= ~OFFSET(gpio);
	writel(val, gchip->base + PDR(gpio));

	val = readl(gchip->base + DDR(gpio));
	val |= OFFSET(gpio);
	writel(val, gchip->base + DDR(gpio));

	spin_unlock_irqrestore(&gchip->lock, flags);

	return 0;
}

static int mb86s70_gpio_get(struct gpio_chip *gc, unsigned gpio)
{
	struct mb86s70_gpio_chip *gchip = gpiochip_get_data(gc);

	return !!(readl(gchip->base + PDR(gpio)) & OFFSET(gpio));
}

static void mb86s70_gpio_set(struct gpio_chip *gc, unsigned gpio, int value)
{
	struct mb86s70_gpio_chip *gchip = gpiochip_get_data(gc);
	unsigned long flags;
	unsigned char val;

	spin_lock_irqsave(&gchip->lock, flags);

	val = readl(gchip->base + PDR(gpio));
	if (value)
		val |= OFFSET(gpio);
	else
		val &= ~OFFSET(gpio);
	writel(val, gchip->base + PDR(gpio));

	spin_unlock_irqrestore(&gchip->lock, flags);
}

static int mb86s70_gpio_probe(struct platform_device *pdev)
{
	struct mb86s70_gpio_chip *gchip;
	struct resource *res;
	int ret;

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

	platform_set_drvdata(pdev, gchip);

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

	gchip->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(gchip->clk))
		return PTR_ERR(gchip->clk);

	clk_prepare_enable(gchip->clk);

	spin_lock_init(&gchip->lock);

	gchip->gc.direction_output = mb86s70_gpio_direction_output;
	gchip->gc.direction_input = mb86s70_gpio_direction_input;
	gchip->gc.request = mb86s70_gpio_request;
	gchip->gc.free = mb86s70_gpio_free;
	gchip->gc.get = mb86s70_gpio_get;
	gchip->gc.set = mb86s70_gpio_set;
	gchip->gc.label = dev_name(&pdev->dev);
	gchip->gc.ngpio = 32;
	gchip->gc.owner = THIS_MODULE;
	gchip->gc.parent = &pdev->dev;
	gchip->gc.base = -1;

	ret = gpiochip_add_data(&gchip->gc, gchip);
	if (ret) {
		dev_err(&pdev->dev, "couldn't register gpio driver\n");
		clk_disable_unprepare(gchip->clk);
	}

	return ret;
}

static int mb86s70_gpio_remove(struct platform_device *pdev)
{
	struct mb86s70_gpio_chip *gchip = platform_get_drvdata(pdev);

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

	return 0;
}

static const struct of_device_id mb86s70_gpio_dt_ids[] = {
	{ .compatible = "fujitsu,mb86s70-gpio" },
	{ /* sentinel */ }
};

static struct platform_driver mb86s70_gpio_driver = {
	.driver = {
		.name = "mb86s70-gpio",
		.of_match_table = mb86s70_gpio_dt_ids,
	},
	.probe = mb86s70_gpio_probe,
	.remove = mb86s70_gpio_remove,
};

static int __init mb86s70_gpio_init(void)
{
	return platform_driver_register(&mb86s70_gpio_driver);
}
device_initcall(mb86s70_gpio_init);