gpio-vx855.c

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/*
 * Linux GPIOlib driver for the VIA VX855 integrated southbridge GPIO
 *
 * Copyright (C) 2009 VIA Technologies, Inc.
 * Copyright (C) 2010 One Laptop per Child
 * Author: Harald Welte <[email protected]>
 * All rights reserved.
 *
 * 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., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/pci.h>
#include <linux/io.h>

#define MODULE_NAME "vx855_gpio"

/* The VX855 south bridge has the following GPIO pins:
 *  GPI 0...13  General Purpose Input
 *  GPO 0...12  General Purpose Output
 *  GPIO 0...14 General Purpose I/O (Open-Drain)
 */

#define NR_VX855_GPI    14
#define NR_VX855_GPO    13
#define NR_VX855_GPIO   15

#define NR_VX855_GPInO  (NR_VX855_GPI + NR_VX855_GPO)
#define NR_VX855_GP (NR_VX855_GPI + NR_VX855_GPO + NR_VX855_GPIO)

struct vx855_gpio {
    struct gpio_chip gpio;
    spinlock_t lock;
    u32 io_gpi;
    u32 io_gpo;
    bool gpi_reserved;
    bool gpo_reserved;
};

/* resolve a GPIx into the corresponding bit position */
static inline u_int32_t gpi_i_bit(int i)
{
    if (i < 10)
        return 1 << i;
    else
        return 1 << (i + 14);
}

static inline u_int32_t gpo_o_bit(int i)
{
    if (i < 11)
        return 1 << i;
    else
        return 1 << (i + 14);
}

static inline u_int32_t gpio_i_bit(int i)
{
    if (i < 14)
        return 1 << (i + 10);
    else
        return 1 << (i + 14);
}

static inline u_int32_t gpio_o_bit(int i)
{
    if (i < 14)
        return 1 << (i + 11);
    else
        return 1 << (i + 13);
}

/* Mapping betwee numeric GPIO ID and the actual GPIO hardware numbering:
 * 0..13    GPI 0..13
 * 14..26   GPO 0..12
 * 27..41   GPIO 0..14
 */

static int vx855gpio_direction_input(struct gpio_chip *gpio,
                     unsigned int nr)
{
    struct vx855_gpio *vg = container_of(gpio, struct vx855_gpio, gpio);
    unsigned long flags;
    u_int32_t reg_out;

    /* Real GPI bits are always in input direction */
    if (nr < NR_VX855_GPI)
        return 0;

    /* Real GPO bits cannot be put in output direction */
    if (nr < NR_VX855_GPInO)
        return -EINVAL;

    /* Open Drain GPIO have to be set to one */
    spin_lock_irqsave(&vg->lock, flags);
    reg_out = inl(vg->io_gpo);
    reg_out |= gpio_o_bit(nr - NR_VX855_GPInO);
    outl(reg_out, vg->io_gpo);
    spin_unlock_irqrestore(&vg->lock, flags);

    return 0;
}

static int vx855gpio_get(struct gpio_chip *gpio, unsigned int nr)
{
    struct vx855_gpio *vg = container_of(gpio, struct vx855_gpio, gpio);
    u_int32_t reg_in;
    int ret = 0;

    if (nr < NR_VX855_GPI) {
        reg_in = inl(vg->io_gpi);
        if (reg_in & gpi_i_bit(nr))
            ret = 1;
    } else if (nr < NR_VX855_GPInO) {
        /* GPO don't have an input bit, we need to read it
         * back from the output register */
        reg_in = inl(vg->io_gpo);
        if (reg_in & gpo_o_bit(nr - NR_VX855_GPI))
            ret = 1;
    } else {
        reg_in = inl(vg->io_gpi);
        if (reg_in & gpio_i_bit(nr - NR_VX855_GPInO))
            ret = 1;
    }

    return ret;
}

static void vx855gpio_set(struct gpio_chip *gpio, unsigned int nr,
              int val)
{
    struct vx855_gpio *vg = container_of(gpio, struct vx855_gpio, gpio);
    unsigned long flags;
    u_int32_t reg_out;

    /* True GPI cannot be switched to output mode */
    if (nr < NR_VX855_GPI)
        return;

    spin_lock_irqsave(&vg->lock, flags);
    reg_out = inl(vg->io_gpo);
    if (nr < NR_VX855_GPInO) {
        if (val)
            reg_out |= gpo_o_bit(nr - NR_VX855_GPI);
        else
            reg_out &= ~gpo_o_bit(nr - NR_VX855_GPI);
    } else {
        if (val)
            reg_out |= gpio_o_bit(nr - NR_VX855_GPInO);
        else
            reg_out &= ~gpio_o_bit(nr - NR_VX855_GPInO);
    }
    outl(reg_out, vg->io_gpo);
    spin_unlock_irqrestore(&vg->lock, flags);
}

static int vx855gpio_direction_output(struct gpio_chip *gpio,
                      unsigned int nr, int val)
{
    /* True GPI cannot be switched to output mode */
    if (nr < NR_VX855_GPI)
        return -EINVAL;

    /* True GPO don't need to be switched to output mode,
     * and GPIO are open-drain, i.e. also need no switching,
     * so all we do is set the level */
    vx855gpio_set(gpio, nr, val);

    return 0;
}

static const char *vx855gpio_names[NR_VX855_GP] = {
    "VX855_GPI0", "VX855_GPI1", "VX855_GPI2", "VX855_GPI3", "VX855_GPI4",
    "VX855_GPI5", "VX855_GPI6", "VX855_GPI7", "VX855_GPI8", "VX855_GPI9",
    "VX855_GPI10", "VX855_GPI11", "VX855_GPI12", "VX855_GPI13",
    "VX855_GPO0", "VX855_GPO1", "VX855_GPO2", "VX855_GPO3", "VX855_GPO4",
    "VX855_GPO5", "VX855_GPO6", "VX855_GPO7", "VX855_GPO8", "VX855_GPO9",
    "VX855_GPO10", "VX855_GPO11", "VX855_GPO12",
    "VX855_GPIO0", "VX855_GPIO1", "VX855_GPIO2", "VX855_GPIO3",
    "VX855_GPIO4", "VX855_GPIO5", "VX855_GPIO6", "VX855_GPIO7",
    "VX855_GPIO8", "VX855_GPIO9", "VX855_GPIO10", "VX855_GPIO11",
    "VX855_GPIO12", "VX855_GPIO13", "VX855_GPIO14"
};

static void vx855gpio_gpio_setup(struct vx855_gpio *vg)
{
    struct gpio_chip *c = &vg->gpio;

    c->label = "VX855 South Bridge";
    c->owner = THIS_MODULE;
    c->direction_input = vx855gpio_direction_input;
    c->direction_output = vx855gpio_direction_output;
    c->get = vx855gpio_get;
    c->set = vx855gpio_set;
    c->dbg_show = NULL;
    c->base = 0;
    c->ngpio = NR_VX855_GP;
    c->can_sleep = 0;
    c->names = vx855gpio_names;
}

/* This platform device is ordinarily registered by the vx855 mfd driver */
static __devinit int vx855gpio_probe(struct platform_device *pdev)
{
    struct resource *res_gpi;
    struct resource *res_gpo;
    struct vx855_gpio *vg;
    int ret;

    res_gpi = platform_get_resource(pdev, IORESOURCE_IO, 0);
    res_gpo = platform_get_resource(pdev, IORESOURCE_IO, 1);
    if (!res_gpi || !res_gpo)
        return -EBUSY;

    vg = kzalloc(sizeof(*vg), GFP_KERNEL);
    if (!vg)
        return -ENOMEM;

    platform_set_drvdata(pdev, vg);

    dev_info(&pdev->dev, "found VX855 GPIO controller\n");
    vg->io_gpi = res_gpi->start;
    vg->io_gpo = res_gpo->start;
    spin_lock_init(&vg->lock);

    /*
     * A single byte is used to control various GPIO ports on the VX855,
     * and in the case of the OLPC XO-1.5, some of those ports are used
     * for switches that are interpreted and exposed through ACPI. ACPI
     * will have reserved the region, so our own reservation will not
     * succeed. Ignore and continue.
     */

    if (!request_region(res_gpi->start, resource_size(res_gpi),
            MODULE_NAME "_gpi"))
        dev_warn(&pdev->dev,
            "GPI I/O resource busy, probably claimed by ACPI\n");
    else
        vg->gpi_reserved = true;

    if (!request_region(res_gpo->start, resource_size(res_gpo),
            MODULE_NAME "_gpo"))
        dev_warn(&pdev->dev,
            "GPO I/O resource busy, probably claimed by ACPI\n");
    else
        vg->gpo_reserved = true;

    vx855gpio_gpio_setup(vg);

    ret = gpiochip_add(&vg->gpio);
    if (ret) {
        dev_err(&pdev->dev, "failed to register GPIOs\n");
        goto out_release;
    }

    return 0;

out_release:
    if (vg->gpi_reserved)
        release_region(res_gpi->start, resource_size(res_gpi));
    if (vg->gpo_reserved)
        release_region(res_gpi->start, resource_size(res_gpo));
    platform_set_drvdata(pdev, NULL);
    kfree(vg);
    return ret;
}

static int __devexit vx855gpio_remove(struct platform_device *pdev)
{
    struct vx855_gpio *vg = platform_get_drvdata(pdev);
    struct resource *res;

    if (gpiochip_remove(&vg->gpio))
        dev_err(&pdev->dev, "unable to remove gpio_chip?\n");

    if (vg->gpi_reserved) {
        res = platform_get_resource(pdev, IORESOURCE_IO, 0);
        release_region(res->start, resource_size(res));
    }
    if (vg->gpo_reserved) {
        res = platform_get_resource(pdev, IORESOURCE_IO, 1);
        release_region(res->start, resource_size(res));
    }

    platform_set_drvdata(pdev, NULL);
    kfree(vg);
    return 0;
}

static struct platform_driver vx855gpio_driver = {
    .driver = {
        .name   = MODULE_NAME,
        .owner  = THIS_MODULE,
    },
    .probe      = vx855gpio_probe,
    .remove     = __devexit_p(vx855gpio_remove),
};

module_platform_driver(vx855gpio_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <[email protected]>");
MODULE_DESCRIPTION("GPIO driver for the VIA VX855 chipset");
MODULE_ALIAS("platform:vx855_gpio");