/*
 * RDC321x GPIO driver
 *
 * Copyright (C) 2008, Volker Weiss <dev@tintuc.de>
 * Copyright (C) 2007-2010 Florian Fainelli <florian@openwrt.org>
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/pci.h>
#include <linux/gpio.h>
#include <linux/mfd/rdc321x.h>
#include <linux/slab.h>

struct rdc321x_gpio {
	spinlock_t		lock;
	struct pci_dev		*sb_pdev;
	u32			data_reg[2];
	int			reg1_ctrl_base;
	int			reg1_data_base;
	int			reg2_ctrl_base;
	int			reg2_data_base;
	struct gpio_chip	chip;
};

/* read GPIO pin */
static int rdc_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
{
	struct rdc321x_gpio *gpch;
	u32 value = 0;
	int reg;

	gpch = gpiochip_get_data(chip);
	reg = gpio < 32 ? gpch->reg1_data_base : gpch->reg2_data_base;

	spin_lock(&gpch->lock);
	pci_write_config_dword(gpch->sb_pdev, reg,
					gpch->data_reg[gpio < 32 ? 0 : 1]);
	pci_read_config_dword(gpch->sb_pdev, reg, &value);
	spin_unlock(&gpch->lock);

	return (1 << (gpio & 0x1f)) & value ? 1 : 0;
}

static void rdc_gpio_set_value_impl(struct gpio_chip *chip,
				unsigned gpio, int value)
{
	struct rdc321x_gpio *gpch;
	int reg = (gpio < 32) ? 0 : 1;

	gpch = gpiochip_get_data(chip);

	if (value)
		gpch->data_reg[reg] |= 1 << (gpio & 0x1f);
	else
		gpch->data_reg[reg] &= ~(1 << (gpio & 0x1f));

	pci_write_config_dword(gpch->sb_pdev,
			reg ? gpch->reg2_data_base : gpch->reg1_data_base,
			gpch->data_reg[reg]);
}

/* set GPIO pin to value */
static void rdc_gpio_set_value(struct gpio_chip *chip,
				unsigned gpio, int value)
{
	struct rdc321x_gpio *gpch;

	gpch = gpiochip_get_data(chip);
	spin_lock(&gpch->lock);
	rdc_gpio_set_value_impl(chip, gpio, value);
	spin_unlock(&gpch->lock);
}

static int rdc_gpio_config(struct gpio_chip *chip,
				unsigned gpio, int value)
{
	struct rdc321x_gpio *gpch;
	int err;
	u32 reg;

	gpch = gpiochip_get_data(chip);

	spin_lock(&gpch->lock);
	err = pci_read_config_dword(gpch->sb_pdev, gpio < 32 ?
			gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, &reg);
	if (err)
		goto unlock;

	reg |= 1 << (gpio & 0x1f);

	err = pci_write_config_dword(gpch->sb_pdev, gpio < 32 ?
			gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, reg);
	if (err)
		goto unlock;

	rdc_gpio_set_value_impl(chip, gpio, value);

unlock:
	spin_unlock(&gpch->lock);

	return err;
}

/* configure GPIO pin as input */
static int rdc_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
{
	return rdc_gpio_config(chip, gpio, 1);
}

/*
 * Cache the initial value of both GPIO data registers
 */
static int rdc321x_gpio_probe(struct platform_device *pdev)
{
	int err;
	struct resource *r;
	struct rdc321x_gpio *rdc321x_gpio_dev;
	struct rdc321x_gpio_pdata *pdata;

	pdata = dev_get_platdata(&pdev->dev);
	if (!pdata) {
		dev_err(&pdev->dev, "no platform data supplied\n");
		return -ENODEV;
	}

	rdc321x_gpio_dev = devm_kzalloc(&pdev->dev, sizeof(struct rdc321x_gpio),
					GFP_KERNEL);
	if (!rdc321x_gpio_dev)
		return -ENOMEM;

	r = platform_get_resource_byname(pdev, IORESOURCE_IO, "gpio-reg1");
	if (!r) {
		dev_err(&pdev->dev, "failed to get gpio-reg1 resource\n");
		return -ENODEV;
	}

	spin_lock_init(&rdc321x_gpio_dev->lock);
	rdc321x_gpio_dev->sb_pdev = pdata->sb_pdev;
	rdc321x_gpio_dev->reg1_ctrl_base = r->start;
	rdc321x_gpio_dev->reg1_data_base = r->start + 0x4;

	r = platform_get_resource_byname(pdev, IORESOURCE_IO, "gpio-reg2");
	if (!r) {
		dev_err(&pdev->dev, "failed to get gpio-reg2 resource\n");
		return -ENODEV;
	}

	rdc321x_gpio_dev->reg2_ctrl_base = r->start;
	rdc321x_gpio_dev->reg2_data_base = r->start + 0x4;

	rdc321x_gpio_dev->chip.label = "rdc321x-gpio";
	rdc321x_gpio_dev->chip.owner = THIS_MODULE;
	rdc321x_gpio_dev->chip.direction_input = rdc_gpio_direction_input;
	rdc321x_gpio_dev->chip.direction_output = rdc_gpio_config;
	rdc321x_gpio_dev->chip.get = rdc_gpio_get_value;
	rdc321x_gpio_dev->chip.set = rdc_gpio_set_value;
	rdc321x_gpio_dev->chip.base = 0;
	rdc321x_gpio_dev->chip.ngpio = pdata->max_gpios;

	platform_set_drvdata(pdev, rdc321x_gpio_dev);

	/* This might not be, what others (BIOS, bootloader, etc.)
	   wrote to these registers before, but it's a good guess. Still
	   better than just using 0xffffffff. */
	err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev,
					rdc321x_gpio_dev->reg1_data_base,
					&rdc321x_gpio_dev->data_reg[0]);
	if (err)
		return err;

	err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev,
					rdc321x_gpio_dev->reg2_data_base,
					&rdc321x_gpio_dev->data_reg[1]);
	if (err)
		return err;

	dev_info(&pdev->dev, "registering %d GPIOs\n",
					rdc321x_gpio_dev->chip.ngpio);
	return devm_gpiochip_add_data(&pdev->dev, &rdc321x_gpio_dev->chip,
				      rdc321x_gpio_dev);
}

static struct platform_driver rdc321x_gpio_driver = {
	.driver.name	= "rdc321x-gpio",
	.probe		= rdc321x_gpio_probe,
};

module_platform_driver(rdc321x_gpio_driver);

MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
MODULE_DESCRIPTION("RDC321x GPIO driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rdc321x-gpio");
