mdio-mux-gpio.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2011, 2012 Cavium, Inc.
 */

#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/of_mdio.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/phy.h>
#include <linux/mdio-mux.h>
#include <linux/of_gpio.h>

#define DRV_VERSION "1.0"
#define DRV_DESCRIPTION "GPIO controlled MDIO bus multiplexer driver"

#define MDIO_MUX_GPIO_MAX_BITS 8

struct mdio_mux_gpio_state {
    int gpio[MDIO_MUX_GPIO_MAX_BITS];
    unsigned int num_gpios;
    void *mux_handle;
};

static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
                   void *data)
{
    int change;
    unsigned int n;
    struct mdio_mux_gpio_state *s = data;

    if (current_child == desired_child)
        return 0;

    change = current_child == -1 ? -1 : current_child ^ desired_child;

    for (n = 0; n < s->num_gpios; n++) {
        if (change & 1)
            gpio_set_value_cansleep(s->gpio[n],
                        (desired_child & 1) != 0);
        change >>= 1;
        desired_child >>= 1;
    }

    return 0;
}

static int __devinit mdio_mux_gpio_probe(struct platform_device *pdev)
{
    enum of_gpio_flags f;
    struct mdio_mux_gpio_state *s;
    unsigned int num_gpios;
    unsigned int n;
    int r;

    if (!pdev->dev.of_node)
        return -ENODEV;

    num_gpios = of_gpio_count(pdev->dev.of_node);
    if (num_gpios == 0 || num_gpios > MDIO_MUX_GPIO_MAX_BITS)
        return -ENODEV;

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

    s->num_gpios = num_gpios;

    for (n = 0; n < num_gpios; ) {
        int gpio = of_get_gpio_flags(pdev->dev.of_node, n, &f);
        if (gpio < 0) {
            r = (gpio == -ENODEV) ? -EPROBE_DEFER : gpio;
            goto err;
        }
        s->gpio[n] = gpio;

        n++;

        r = gpio_request(gpio, "mdio_mux_gpio");
        if (r)
            goto err;

        r = gpio_direction_output(gpio, 0);
        if (r)
            goto err;
    }

    r = mdio_mux_init(&pdev->dev,
              mdio_mux_gpio_switch_fn, &s->mux_handle, s);

    if (r == 0) {
        pdev->dev.platform_data = s;
        return 0;
    }
err:
    while (n) {
        n--;
        gpio_free(s->gpio[n]);
    }
    return r;
}

static int __devexit mdio_mux_gpio_remove(struct platform_device *pdev)
{
    struct mdio_mux_gpio_state *s = pdev->dev.platform_data;
    mdio_mux_uninit(s->mux_handle);
    return 0;
}

static struct of_device_id mdio_mux_gpio_match[] = {
    {
        .compatible = "mdio-mux-gpio",
    },
    {
        /* Legacy compatible property. */
        .compatible = "cavium,mdio-mux-sn74cbtlv3253",
    },
    {},
};
MODULE_DEVICE_TABLE(of, mdio_mux_gpio_match);

static struct platform_driver mdio_mux_gpio_driver = {
    .driver = {
        .name       = "mdio-mux-gpio",
        .owner      = THIS_MODULE,
        .of_match_table = mdio_mux_gpio_match,
    },
    .probe      = mdio_mux_gpio_probe,
    .remove     = __devexit_p(mdio_mux_gpio_remove),
};

module_platform_driver(mdio_mux_gpio_driver);

MODULE_DESCRIPTION(DRV_DESCRIPTION);
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("David Daney");
MODULE_LICENSE("GPL");