/*
 * 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 = container_of(chip, struct rdc321x_gpio, 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 = container_of(chip, struct rdc321x_gpio, 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 = container_of(chip, struct rdc321x_gpio, 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 = container_of(chip, struct rdc321x_gpio, 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 = pdev->dev.platform_data;
        if (!pdata) {
                dev_err(&pdev->dev, "no platform data supplied\n");
                return -ENODEV;
        }

        rdc321x_gpio_dev = kzalloc(sizeof(struct rdc321x_gpio), GFP_KERNEL);
        if (!rdc321x_gpio_dev) {
                dev_err(&pdev->dev, "failed to allocate private data\n");
                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");
                err = -ENODEV;
                goto out_free;
        }

        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");
                err = -ENODEV;
                goto out_free;
        }

        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)
                goto out_drvdata;

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

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

out_drvdata:
        platform_set_drvdata(pdev, NULL);
out_free:
        kfree(rdc321x_gpio_dev);
        return err;
}

static int rdc321x_gpio_remove(struct platform_device *pdev)
{
        int ret;
        struct rdc321x_gpio *rdc321x_gpio_dev = platform_get_drvdata(pdev);

        ret = gpiochip_remove(&rdc321x_gpio_dev->chip);
        if (ret)
                dev_err(&pdev->dev, "failed to unregister chip\n");

        kfree(rdc321x_gpio_dev);
        platform_set_drvdata(pdev, NULL);

        return ret;
}

static struct platform_driver rdc321x_gpio_driver = {
        .driver.name    = "rdc321x-gpio",
        .driver.owner   = THIS_MODULE,
        .probe          = rdc321x_gpio_probe,
        .remove         = rdc321x_gpio_remove,
};

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");