gpio_vbus.c

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/*
 * gpio-vbus.c - simple GPIO VBUS sensing driver for B peripheral devices
 *
 * Copyright (c) 2008 Philipp Zabel <[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/kernel.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/usb.h>
#include <linux/workqueue.h>

#include <linux/regulator/consumer.h>

#include <linux/usb/gadget.h>
#include <linux/usb/gpio_vbus.h>
#include <linux/usb/otg.h>


/*
 * A simple GPIO VBUS sensing driver for B peripheral only devices
 * with internal transceivers. It can control a D+ pullup GPIO and
 * a regulator to limit the current drawn from VBUS.
 *
 * Needs to be loaded before the UDC driver that will use it.
 */
struct gpio_vbus_data {
    struct usb_phy      phy;
    struct device          *dev;
    struct regulator       *vbus_draw;
    int         vbus_draw_enabled;
    unsigned        mA;
    struct delayed_work work;
    int         vbus;
    int         irq;
};


/*
 * This driver relies on "both edges" triggering.  VBUS has 100 msec to
 * stabilize, so the peripheral controller driver may need to cope with
 * some bouncing due to current surges (e.g. charging local capacitance)
 * and contact chatter.
 *
 * REVISIT in desperate straits, toggling between rising and falling
 * edges might be workable.
 */
#define VBUS_IRQ_FLAGS \
    (IRQF_SHARED | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)


/* interface to regulator framework */
static void set_vbus_draw(struct gpio_vbus_data *gpio_vbus, unsigned mA)
{
    struct regulator *vbus_draw = gpio_vbus->vbus_draw;
    int enabled;

    if (!vbus_draw)
        return;

    enabled = gpio_vbus->vbus_draw_enabled;
    if (mA) {
        regulator_set_current_limit(vbus_draw, 0, 1000 * mA);
        if (!enabled) {
            regulator_enable(vbus_draw);
            gpio_vbus->vbus_draw_enabled = 1;
        }
    } else {
        if (enabled) {
            regulator_disable(vbus_draw);
            gpio_vbus->vbus_draw_enabled = 0;
        }
    }
    gpio_vbus->mA = mA;
}

static int is_vbus_powered(struct gpio_vbus_mach_info *pdata)
{
    int vbus;

    vbus = gpio_get_value(pdata->gpio_vbus);
    if (pdata->gpio_vbus_inverted)
        vbus = !vbus;

    return vbus;
}

static void gpio_vbus_work(struct work_struct *work)
{
    struct gpio_vbus_data *gpio_vbus =
        container_of(work, struct gpio_vbus_data, work.work);
    struct gpio_vbus_mach_info *pdata = gpio_vbus->dev->platform_data;
    int gpio, status, vbus;

    if (!gpio_vbus->phy.otg->gadget)
        return;

    vbus = is_vbus_powered(pdata);
    if ((vbus ^ gpio_vbus->vbus) == 0)
        return;
    gpio_vbus->vbus = vbus;

    /* Peripheral controllers which manage the pullup themselves won't have
     * gpio_pullup configured here.  If it's configured here, we'll do what
     * isp1301_omap::b_peripheral() does and enable the pullup here... although
     * that may complicate usb_gadget_{,dis}connect() support.
     */
    gpio = pdata->gpio_pullup;

    if (vbus) {
        status = USB_EVENT_VBUS;
        gpio_vbus->phy.state = OTG_STATE_B_PERIPHERAL;
        gpio_vbus->phy.last_event = status;
        usb_gadget_vbus_connect(gpio_vbus->phy.otg->gadget);

        /* drawing a "unit load" is *always* OK, except for OTG */
        set_vbus_draw(gpio_vbus, 100);

        /* optionally enable D+ pullup */
        if (gpio_is_valid(gpio))
            gpio_set_value(gpio, !pdata->gpio_pullup_inverted);

        atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
                       status, gpio_vbus->phy.otg->gadget);
    } else {
        /* optionally disable D+ pullup */
        if (gpio_is_valid(gpio))
            gpio_set_value(gpio, pdata->gpio_pullup_inverted);

        set_vbus_draw(gpio_vbus, 0);

        usb_gadget_vbus_disconnect(gpio_vbus->phy.otg->gadget);
        status = USB_EVENT_NONE;
        gpio_vbus->phy.state = OTG_STATE_B_IDLE;
        gpio_vbus->phy.last_event = status;

        atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
                       status, gpio_vbus->phy.otg->gadget);
    }
}

/* VBUS change IRQ handler */
static irqreturn_t gpio_vbus_irq(int irq, void *data)
{
    struct platform_device *pdev = data;
    struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
    struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
    struct usb_otg *otg = gpio_vbus->phy.otg;

    dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
        is_vbus_powered(pdata) ? "supplied" : "inactive",
        otg->gadget ? otg->gadget->name : "none");

    if (otg->gadget)
        schedule_delayed_work(&gpio_vbus->work, msecs_to_jiffies(100));

    return IRQ_HANDLED;
}

/* OTG transceiver interface */

/* bind/unbind the peripheral controller */
static int gpio_vbus_set_peripheral(struct usb_otg *otg,
                    struct usb_gadget *gadget)
{
    struct gpio_vbus_data *gpio_vbus;
    struct gpio_vbus_mach_info *pdata;
    struct platform_device *pdev;
    int gpio;

    gpio_vbus = container_of(otg->phy, struct gpio_vbus_data, phy);
    pdev = to_platform_device(gpio_vbus->dev);
    pdata = gpio_vbus->dev->platform_data;
    gpio = pdata->gpio_pullup;

    if (!gadget) {
        dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
            otg->gadget->name);

        /* optionally disable D+ pullup */
        if (gpio_is_valid(gpio))
            gpio_set_value(gpio, pdata->gpio_pullup_inverted);

        set_vbus_draw(gpio_vbus, 0);

        usb_gadget_vbus_disconnect(otg->gadget);
        otg->phy->state = OTG_STATE_UNDEFINED;

        otg->gadget = NULL;
        return 0;
    }

    otg->gadget = gadget;
    dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);

    /* initialize connection state */
    gpio_vbus->vbus = 0; /* start with disconnected */
    gpio_vbus_irq(gpio_vbus->irq, pdev);
    return 0;
}

/* effective for B devices, ignored for A-peripheral */
static int gpio_vbus_set_power(struct usb_phy *phy, unsigned mA)
{
    struct gpio_vbus_data *gpio_vbus;

    gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);

    if (phy->state == OTG_STATE_B_PERIPHERAL)
        set_vbus_draw(gpio_vbus, mA);
    return 0;
}

/* for non-OTG B devices: set/clear transceiver suspend mode */
static int gpio_vbus_set_suspend(struct usb_phy *phy, int suspend)
{
    struct gpio_vbus_data *gpio_vbus;

    gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);

    /* draw max 0 mA from vbus in suspend mode; or the previously
     * recorded amount of current if not suspended
     *
     * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
     * if they're wake-enabled ... we don't handle that yet.
     */
    return gpio_vbus_set_power(phy, suspend ? 0 : gpio_vbus->mA);
}

/* platform driver interface */

static int __init gpio_vbus_probe(struct platform_device *pdev)
{
    struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
    struct gpio_vbus_data *gpio_vbus;
    struct resource *res;
    int err, gpio, irq;
    unsigned long irqflags;

    if (!pdata || !gpio_is_valid(pdata->gpio_vbus))
        return -EINVAL;
    gpio = pdata->gpio_vbus;

    gpio_vbus = kzalloc(sizeof(struct gpio_vbus_data), GFP_KERNEL);
    if (!gpio_vbus)
        return -ENOMEM;

    gpio_vbus->phy.otg = kzalloc(sizeof(struct usb_otg), GFP_KERNEL);
    if (!gpio_vbus->phy.otg) {
        kfree(gpio_vbus);
        return -ENOMEM;
    }

    platform_set_drvdata(pdev, gpio_vbus);
    gpio_vbus->dev = &pdev->dev;
    gpio_vbus->phy.label = "gpio-vbus";
    gpio_vbus->phy.set_power = gpio_vbus_set_power;
    gpio_vbus->phy.set_suspend = gpio_vbus_set_suspend;
    gpio_vbus->phy.state = OTG_STATE_UNDEFINED;

    gpio_vbus->phy.otg->phy = &gpio_vbus->phy;
    gpio_vbus->phy.otg->set_peripheral = gpio_vbus_set_peripheral;

    err = gpio_request(gpio, "vbus_detect");
    if (err) {
        dev_err(&pdev->dev, "can't request vbus gpio %d, err: %d\n",
            gpio, err);
        goto err_gpio;
    }
    gpio_direction_input(gpio);

    res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    if (res) {
        irq = res->start;
        irqflags = (res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
    } else {
        irq = gpio_to_irq(gpio);
        irqflags = VBUS_IRQ_FLAGS;
    }

    gpio_vbus->irq = irq;

    /* if data line pullup is in use, initialize it to "not pulling up" */
    gpio = pdata->gpio_pullup;
    if (gpio_is_valid(gpio)) {
        err = gpio_request(gpio, "udc_pullup");
        if (err) {
            dev_err(&pdev->dev,
                "can't request pullup gpio %d, err: %d\n",
                gpio, err);
            gpio_free(pdata->gpio_vbus);
            goto err_gpio;
        }
        gpio_direction_output(gpio, pdata->gpio_pullup_inverted);
    }

    err = request_irq(irq, gpio_vbus_irq, irqflags, "vbus_detect", pdev);
    if (err) {
        dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
            irq, err);
        goto err_irq;
    }

    ATOMIC_INIT_NOTIFIER_HEAD(&gpio_vbus->phy.notifier);

    INIT_DELAYED_WORK(&gpio_vbus->work, gpio_vbus_work);

    gpio_vbus->vbus_draw = regulator_get(&pdev->dev, "vbus_draw");
    if (IS_ERR(gpio_vbus->vbus_draw)) {
        dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
            PTR_ERR(gpio_vbus->vbus_draw));
        gpio_vbus->vbus_draw = NULL;
    }

    /* only active when a gadget is registered */
    err = usb_add_phy(&gpio_vbus->phy, USB_PHY_TYPE_USB2);
    if (err) {
        dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
            err);
        goto err_otg;
    }

    device_init_wakeup(&pdev->dev, pdata->wakeup);

    return 0;
err_otg:
    regulator_put(gpio_vbus->vbus_draw);
    free_irq(irq, pdev);
err_irq:
    if (gpio_is_valid(pdata->gpio_pullup))
        gpio_free(pdata->gpio_pullup);
    gpio_free(pdata->gpio_vbus);
err_gpio:
    platform_set_drvdata(pdev, NULL);
    kfree(gpio_vbus->phy.otg);
    kfree(gpio_vbus);
    return err;
}

static int __exit gpio_vbus_remove(struct platform_device *pdev)
{
    struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
    struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
    int gpio = pdata->gpio_vbus;

    device_init_wakeup(&pdev->dev, 0);
    cancel_delayed_work_sync(&gpio_vbus->work);
    regulator_put(gpio_vbus->vbus_draw);

    usb_remove_phy(&gpio_vbus->phy);

    free_irq(gpio_vbus->irq, pdev);
    if (gpio_is_valid(pdata->gpio_pullup))
        gpio_free(pdata->gpio_pullup);
    gpio_free(gpio);
    platform_set_drvdata(pdev, NULL);
    kfree(gpio_vbus->phy.otg);
    kfree(gpio_vbus);

    return 0;
}

#ifdef CONFIG_PM
static int gpio_vbus_pm_suspend(struct device *dev)
{
    struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);

    if (device_may_wakeup(dev))
        enable_irq_wake(gpio_vbus->irq);

    return 0;
}

static int gpio_vbus_pm_resume(struct device *dev)
{
    struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);

    if (device_may_wakeup(dev))
        disable_irq_wake(gpio_vbus->irq);

    return 0;
}

static const struct dev_pm_ops gpio_vbus_dev_pm_ops = {
    .suspend    = gpio_vbus_pm_suspend,
    .resume     = gpio_vbus_pm_resume,
};
#endif

/* NOTE:  the gpio-vbus device may *NOT* be hotplugged */

MODULE_ALIAS("platform:gpio-vbus");

static struct platform_driver gpio_vbus_driver = {
    .driver = {
        .name  = "gpio-vbus",
        .owner = THIS_MODULE,
#ifdef CONFIG_PM
        .pm = &gpio_vbus_dev_pm_ops,
#endif
    },
    .remove  = __exit_p(gpio_vbus_remove),
};

static int __init gpio_vbus_init(void)
{
    return platform_driver_probe(&gpio_vbus_driver, gpio_vbus_probe);
}
module_init(gpio_vbus_init);

static void __exit gpio_vbus_exit(void)
{
    platform_driver_unregister(&gpio_vbus_driver);
}
module_exit(gpio_vbus_exit);

MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
MODULE_AUTHOR("Philipp Zabel");
MODULE_LICENSE("GPL");