gpio-rdc321x.c

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/*
 * RDC321x GPIO driver
 *
 * Copyright (C) 2008, Volker Weiss <[email protected]>
 * Copyright (C) 2007-2010 Florian Fainelli <[email protected]>
 *
 * 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 __devinit 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 __devexit 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     = __devexit_p(rdc321x_gpio_remove),
};

module_platform_driver(rdc321x_gpio_driver);

MODULE_AUTHOR("Florian Fainelli <[email protected]>");
MODULE_DESCRIPTION("RDC321x GPIO driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rdc321x-gpio");