w1-gpio.c

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/*
 * w1-gpio - GPIO w1 bus master driver
 *
 * Copyright (C) 2007 Ville Syrjala <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/w1-gpio.h>
#include <linux/gpio.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>

#include "../w1.h"
#include "../w1_int.h"

static void w1_gpio_write_bit_dir(void *data, u8 bit)
{
    struct w1_gpio_platform_data *pdata = data;

    if (bit)
        gpio_direction_input(pdata->pin);
    else
        gpio_direction_output(pdata->pin, 0);
}

static void w1_gpio_write_bit_val(void *data, u8 bit)
{
    struct w1_gpio_platform_data *pdata = data;

    gpio_set_value(pdata->pin, bit);
}

static u8 w1_gpio_read_bit(void *data)
{
    struct w1_gpio_platform_data *pdata = data;

    return gpio_get_value(pdata->pin) ? 1 : 0;
}

#ifdef CONFIG_OF
static struct of_device_id w1_gpio_dt_ids[] = {
    { .compatible = "w1-gpio" },
    {}
};
MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);

static int w1_gpio_probe_dt(struct platform_device *pdev)
{
    struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
    struct device_node *np = pdev->dev.of_node;
    const struct of_device_id *of_id =
            of_match_device(w1_gpio_dt_ids, &pdev->dev);

    if (!of_id)
        return 0;

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

    if (of_get_property(np, "linux,open-drain", NULL))
        pdata->is_open_drain = 1;

    pdata->pin = of_get_gpio(np, 0);
    pdata->ext_pullup_enable_pin = of_get_gpio(np, 1);
    pdev->dev.platform_data = pdata;

    return 0;
}
#else
static int w1_gpio_probe_dt(struct platform_device *pdev)
{
    return 0;
}
#endif

static int __init w1_gpio_probe(struct platform_device *pdev)
{
    struct w1_bus_master *master;
    struct w1_gpio_platform_data *pdata;
    int err;

    err = w1_gpio_probe_dt(pdev);
    if (err < 0)
        return err;

    pdata = pdev->dev.platform_data;

    if (!pdata)
        return -ENXIO;

    master = kzalloc(sizeof(struct w1_bus_master), GFP_KERNEL);
    if (!master)
        return -ENOMEM;

    err = gpio_request(pdata->pin, "w1");
    if (err)
        goto free_master;

    if (gpio_is_valid(pdata->ext_pullup_enable_pin)) {
        err = gpio_request_one(pdata->ext_pullup_enable_pin,
                       GPIOF_INIT_LOW, "w1 pullup");
        if (err < 0)
            goto free_gpio;
    }

    master->data = pdata;
    master->read_bit = w1_gpio_read_bit;

    if (pdata->is_open_drain) {
        gpio_direction_output(pdata->pin, 1);
        master->write_bit = w1_gpio_write_bit_val;
    } else {
        gpio_direction_input(pdata->pin);
        master->write_bit = w1_gpio_write_bit_dir;
    }

    err = w1_add_master_device(master);
    if (err)
        goto free_gpio_ext_pu;

    if (pdata->enable_external_pullup)
        pdata->enable_external_pullup(1);

    if (gpio_is_valid(pdata->ext_pullup_enable_pin))
        gpio_set_value(pdata->ext_pullup_enable_pin, 1);

    platform_set_drvdata(pdev, master);

    return 0;

 free_gpio_ext_pu:
    if (gpio_is_valid(pdata->ext_pullup_enable_pin))
        gpio_free(pdata->ext_pullup_enable_pin);
 free_gpio:
    gpio_free(pdata->pin);
 free_master:
    kfree(master);

    return err;
}

static int __exit w1_gpio_remove(struct platform_device *pdev)
{
    struct w1_bus_master *master = platform_get_drvdata(pdev);
    struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;

    if (pdata->enable_external_pullup)
        pdata->enable_external_pullup(0);

    if (gpio_is_valid(pdata->ext_pullup_enable_pin))
        gpio_set_value(pdata->ext_pullup_enable_pin, 0);

    w1_remove_master_device(master);
    gpio_free(pdata->pin);
    kfree(master);

    return 0;
}

#ifdef CONFIG_PM

static int w1_gpio_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;

    if (pdata->enable_external_pullup)
        pdata->enable_external_pullup(0);

    return 0;
}

static int w1_gpio_resume(struct platform_device *pdev)
{
    struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;

    if (pdata->enable_external_pullup)
        pdata->enable_external_pullup(1);

    return 0;
}

#else
#define w1_gpio_suspend NULL
#define w1_gpio_resume  NULL
#endif

static struct platform_driver w1_gpio_driver = {
    .driver = {
        .name   = "w1-gpio",
        .owner  = THIS_MODULE,
        .of_match_table = of_match_ptr(w1_gpio_dt_ids),
    },
    .remove = __exit_p(w1_gpio_remove),
    .suspend = w1_gpio_suspend,
    .resume = w1_gpio_resume,
};

static int __init w1_gpio_init(void)
{
    return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
}

static void __exit w1_gpio_exit(void)
{
    platform_driver_unregister(&w1_gpio_driver);
}

module_init(w1_gpio_init);
module_exit(w1_gpio_exit);

MODULE_DESCRIPTION("GPIO w1 bus master driver");
MODULE_AUTHOR("Ville Syrjala <[email protected]>");
MODULE_LICENSE("GPL");