gpio_keys.c

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/*
 * Driver for keys on GPIO lines capable of generating interrupts.
 *
 * Copyright 2005 Phil Blundell
 * Copyright 2010, 2011 David Jander <[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/module.h>

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/gpio_keys.h>
#include <linux/workqueue.h>
#include <linux/gpio.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/spinlock.h>

struct gpio_button_data {
    const struct gpio_keys_button *button;
    struct input_dev *input;
    struct timer_list timer;
    struct work_struct work;
    unsigned int timer_debounce;    /* in msecs */
    unsigned int irq;
    spinlock_t lock;
    bool disabled;
    bool key_pressed;
};

struct gpio_keys_drvdata {
    const struct gpio_keys_platform_data *pdata;
    struct input_dev *input;
    struct mutex disable_lock;
    struct gpio_button_data data[0];
};

/*
 * SYSFS interface for enabling/disabling keys and switches:
 *
 * There are 4 attributes under /sys/devices/platform/gpio-keys/
 *  keys [ro]              - bitmap of keys (EV_KEY) which can be
 *                           disabled
 *  switches [ro]          - bitmap of switches (EV_SW) which can be
 *                           disabled
 *  disabled_keys [rw]     - bitmap of keys currently disabled
 *  disabled_switches [rw] - bitmap of switches currently disabled
 *
 * Userland can change these values and hence disable event generation
 * for each key (or switch). Disabling a key means its interrupt line
 * is disabled.
 *
 * For example, if we have following switches set up as gpio-keys:
 *  SW_DOCK = 5
 *  SW_CAMERA_LENS_COVER = 9
 *  SW_KEYPAD_SLIDE = 10
 *  SW_FRONT_PROXIMITY = 11
 * This is read from switches:
 *  11-9,5
 * Next we want to disable proximity (11) and dock (5), we write:
 *  11,5
 * to file disabled_switches. Now proximity and dock IRQs are disabled.
 * This can be verified by reading the file disabled_switches:
 *  11,5
 * If we now want to enable proximity (11) switch we write:
 *  5
 * to disabled_switches.
 *
 * We can disable only those keys which don't allow sharing the irq.
 */

static inline int get_n_events_by_type(int type)
{
    BUG_ON(type != EV_SW && type != EV_KEY);

    return (type == EV_KEY) ? KEY_CNT : SW_CNT;
}

static void gpio_keys_disable_button(struct gpio_button_data *bdata)
{
    if (!bdata->disabled) {
        /*
         * Disable IRQ and possible debouncing timer.
         */
        disable_irq(bdata->irq);
        if (bdata->timer_debounce)
            del_timer_sync(&bdata->timer);

        bdata->disabled = true;
    }
}

static void gpio_keys_enable_button(struct gpio_button_data *bdata)
{
    if (bdata->disabled) {
        enable_irq(bdata->irq);
        bdata->disabled = false;
    }
}

static ssize_t gpio_keys_attr_show_helper(struct gpio_keys_drvdata *ddata,
                      char *buf, unsigned int type,
                      bool only_disabled)
{
    int n_events = get_n_events_by_type(type);
    unsigned long *bits;
    ssize_t ret;
    int i;

    bits = kcalloc(BITS_TO_LONGS(n_events), sizeof(*bits), GFP_KERNEL);
    if (!bits)
        return -ENOMEM;

    for (i = 0; i < ddata->pdata->nbuttons; i++) {
        struct gpio_button_data *bdata = &ddata->data[i];

        if (bdata->button->type != type)
            continue;

        if (only_disabled && !bdata->disabled)
            continue;

        __set_bit(bdata->button->code, bits);
    }

    ret = bitmap_scnlistprintf(buf, PAGE_SIZE - 2, bits, n_events);
    buf[ret++] = '\n';
    buf[ret] = '\0';

    kfree(bits);

    return ret;
}

static ssize_t gpio_keys_attr_store_helper(struct gpio_keys_drvdata *ddata,
                       const char *buf, unsigned int type)
{
    int n_events = get_n_events_by_type(type);
    unsigned long *bits;
    ssize_t error;
    int i;

    bits = kcalloc(BITS_TO_LONGS(n_events), sizeof(*bits), GFP_KERNEL);
    if (!bits)
        return -ENOMEM;

    error = bitmap_parselist(buf, bits, n_events);
    if (error)
        goto out;

    /* First validate */
    for (i = 0; i < ddata->pdata->nbuttons; i++) {
        struct gpio_button_data *bdata = &ddata->data[i];

        if (bdata->button->type != type)
            continue;

        if (test_bit(bdata->button->code, bits) &&
            !bdata->button->can_disable) {
            error = -EINVAL;
            goto out;
        }
    }

    mutex_lock(&ddata->disable_lock);

    for (i = 0; i < ddata->pdata->nbuttons; i++) {
        struct gpio_button_data *bdata = &ddata->data[i];

        if (bdata->button->type != type)
            continue;

        if (test_bit(bdata->button->code, bits))
            gpio_keys_disable_button(bdata);
        else
            gpio_keys_enable_button(bdata);
    }

    mutex_unlock(&ddata->disable_lock);

out:
    kfree(bits);
    return error;
}

#define ATTR_SHOW_FN(name, type, only_disabled)             \
static ssize_t gpio_keys_show_##name(struct device *dev,        \
                     struct device_attribute *attr, \
                     char *buf)             \
{                                   \
    struct platform_device *pdev = to_platform_device(dev);     \
    struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);   \
                                    \
    return gpio_keys_attr_show_helper(ddata, buf,           \
                      type, only_disabled);     \
}

ATTR_SHOW_FN(keys, EV_KEY, false);
ATTR_SHOW_FN(switches, EV_SW, false);
ATTR_SHOW_FN(disabled_keys, EV_KEY, true);
ATTR_SHOW_FN(disabled_switches, EV_SW, true);

/*
 * ATTRIBUTES:
 *
 * /sys/devices/platform/gpio-keys/keys [ro]
 * /sys/devices/platform/gpio-keys/switches [ro]
 */
static DEVICE_ATTR(keys, S_IRUGO, gpio_keys_show_keys, NULL);
static DEVICE_ATTR(switches, S_IRUGO, gpio_keys_show_switches, NULL);

#define ATTR_STORE_FN(name, type)                   \
static ssize_t gpio_keys_store_##name(struct device *dev,       \
                      struct device_attribute *attr,    \
                      const char *buf,          \
                      size_t count)         \
{                                   \
    struct platform_device *pdev = to_platform_device(dev);     \
    struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);   \
    ssize_t error;                          \
                                    \
    error = gpio_keys_attr_store_helper(ddata, buf, type);      \
    if (error)                          \
        return error;                       \
                                    \
    return count;                           \
}

ATTR_STORE_FN(disabled_keys, EV_KEY);
ATTR_STORE_FN(disabled_switches, EV_SW);

/*
 * ATTRIBUTES:
 *
 * /sys/devices/platform/gpio-keys/disabled_keys [rw]
 * /sys/devices/platform/gpio-keys/disables_switches [rw]
 */
static DEVICE_ATTR(disabled_keys, S_IWUSR | S_IRUGO,
           gpio_keys_show_disabled_keys,
           gpio_keys_store_disabled_keys);
static DEVICE_ATTR(disabled_switches, S_IWUSR | S_IRUGO,
           gpio_keys_show_disabled_switches,
           gpio_keys_store_disabled_switches);

static struct attribute *gpio_keys_attrs[] = {
    &dev_attr_keys.attr,
    &dev_attr_switches.attr,
    &dev_attr_disabled_keys.attr,
    &dev_attr_disabled_switches.attr,
    NULL,
};

static struct attribute_group gpio_keys_attr_group = {
    .attrs = gpio_keys_attrs,
};

static void gpio_keys_gpio_report_event(struct gpio_button_data *bdata)
{
    const struct gpio_keys_button *button = bdata->button;
    struct input_dev *input = bdata->input;
    unsigned int type = button->type ?: EV_KEY;
    int state = (gpio_get_value_cansleep(button->gpio) ? 1 : 0) ^ button->active_low;

    if (type == EV_ABS) {
        if (state)
            input_event(input, type, button->code, button->value);
    } else {
        input_event(input, type, button->code, !!state);
    }
    input_sync(input);
}

static void gpio_keys_gpio_work_func(struct work_struct *work)
{
    struct gpio_button_data *bdata =
        container_of(work, struct gpio_button_data, work);

    gpio_keys_gpio_report_event(bdata);

    if (bdata->button->wakeup)
        pm_relax(bdata->input->dev.parent);
}

static void gpio_keys_gpio_timer(unsigned long _data)
{
    struct gpio_button_data *bdata = (struct gpio_button_data *)_data;

    schedule_work(&bdata->work);
}

static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
{
    struct gpio_button_data *bdata = dev_id;

    BUG_ON(irq != bdata->irq);

    if (bdata->button->wakeup)
        pm_stay_awake(bdata->input->dev.parent);
    if (bdata->timer_debounce)
        mod_timer(&bdata->timer,
            jiffies + msecs_to_jiffies(bdata->timer_debounce));
    else
        schedule_work(&bdata->work);

    return IRQ_HANDLED;
}

static void gpio_keys_irq_timer(unsigned long _data)
{
    struct gpio_button_data *bdata = (struct gpio_button_data *)_data;
    struct input_dev *input = bdata->input;
    unsigned long flags;

    spin_lock_irqsave(&bdata->lock, flags);
    if (bdata->key_pressed) {
        input_event(input, EV_KEY, bdata->button->code, 0);
        input_sync(input);
        bdata->key_pressed = false;
    }
    spin_unlock_irqrestore(&bdata->lock, flags);
}

static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id)
{
    struct gpio_button_data *bdata = dev_id;
    const struct gpio_keys_button *button = bdata->button;
    struct input_dev *input = bdata->input;
    unsigned long flags;

    BUG_ON(irq != bdata->irq);

    spin_lock_irqsave(&bdata->lock, flags);

    if (!bdata->key_pressed) {
        if (bdata->button->wakeup)
            pm_wakeup_event(bdata->input->dev.parent, 0);

        input_event(input, EV_KEY, button->code, 1);
        input_sync(input);

        if (!bdata->timer_debounce) {
            input_event(input, EV_KEY, button->code, 0);
            input_sync(input);
            goto out;
        }

        bdata->key_pressed = true;
    }

    if (bdata->timer_debounce)
        mod_timer(&bdata->timer,
            jiffies + msecs_to_jiffies(bdata->timer_debounce));
out:
    spin_unlock_irqrestore(&bdata->lock, flags);
    return IRQ_HANDLED;
}

static int __devinit gpio_keys_setup_key(struct platform_device *pdev,
                     struct input_dev *input,
                     struct gpio_button_data *bdata,
                     const struct gpio_keys_button *button)
{
    const char *desc = button->desc ? button->desc : "gpio_keys";
    struct device *dev = &pdev->dev;
    irq_handler_t isr;
    unsigned long irqflags;
    int irq, error;

    bdata->input = input;
    bdata->button = button;
    spin_lock_init(&bdata->lock);

    if (gpio_is_valid(button->gpio)) {

        error = gpio_request(button->gpio, desc);
        if (error < 0) {
            dev_err(dev, "Failed to request GPIO %d, error %d\n",
                button->gpio, error);
            return error;
        }

        error = gpio_direction_input(button->gpio);
        if (error < 0) {
            dev_err(dev,
                "Failed to configure direction for GPIO %d, error %d\n",
                button->gpio, error);
            goto fail;
        }

        if (button->debounce_interval) {
            error = gpio_set_debounce(button->gpio,
                    button->debounce_interval * 1000);
            /* use timer if gpiolib doesn't provide debounce */
            if (error < 0)
                bdata->timer_debounce =
                        button->debounce_interval;
        }

        irq = gpio_to_irq(button->gpio);
        if (irq < 0) {
            error = irq;
            dev_err(dev,
                "Unable to get irq number for GPIO %d, error %d\n",
                button->gpio, error);
            goto fail;
        }
        bdata->irq = irq;

        INIT_WORK(&bdata->work, gpio_keys_gpio_work_func);
        setup_timer(&bdata->timer,
                gpio_keys_gpio_timer, (unsigned long)bdata);

        isr = gpio_keys_gpio_isr;
        irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;

    } else {
        if (!button->irq) {
            dev_err(dev, "No IRQ specified\n");
            return -EINVAL;
        }
        bdata->irq = button->irq;

        if (button->type && button->type != EV_KEY) {
            dev_err(dev, "Only EV_KEY allowed for IRQ buttons.\n");
            return -EINVAL;
        }

        bdata->timer_debounce = button->debounce_interval;
        setup_timer(&bdata->timer,
                gpio_keys_irq_timer, (unsigned long)bdata);

        isr = gpio_keys_irq_isr;
        irqflags = 0;
    }

    input_set_capability(input, button->type ?: EV_KEY, button->code);

    /*
     * If platform has specified that the button can be disabled,
     * we don't want it to share the interrupt line.
     */
    if (!button->can_disable)
        irqflags |= IRQF_SHARED;

    error = request_any_context_irq(bdata->irq, isr, irqflags, desc, bdata);
    if (error < 0) {
        dev_err(dev, "Unable to claim irq %d; error %d\n",
            bdata->irq, error);
        goto fail;
    }

    return 0;

fail:
    if (gpio_is_valid(button->gpio))
        gpio_free(button->gpio);

    return error;
}

static int gpio_keys_open(struct input_dev *input)
{
    struct gpio_keys_drvdata *ddata = input_get_drvdata(input);
    const struct gpio_keys_platform_data *pdata = ddata->pdata;

    return pdata->enable ? pdata->enable(input->dev.parent) : 0;
}

static void gpio_keys_close(struct input_dev *input)
{
    struct gpio_keys_drvdata *ddata = input_get_drvdata(input);
    const struct gpio_keys_platform_data *pdata = ddata->pdata;

    if (pdata->disable)
        pdata->disable(input->dev.parent);
}

/*
 * Handlers for alternative sources of platform_data
 */

#ifdef CONFIG_OF
/*
 * Translate OpenFirmware node properties into platform_data
 */
static struct gpio_keys_platform_data * __devinit
gpio_keys_get_devtree_pdata(struct device *dev)
{
    struct device_node *node, *pp;
    struct gpio_keys_platform_data *pdata;
    struct gpio_keys_button *button;
    int error;
    int nbuttons;
    int i;

    node = dev->of_node;
    if (!node) {
        error = -ENODEV;
        goto err_out;
    }

    nbuttons = of_get_child_count(node);
    if (nbuttons == 0) {
        error = -ENODEV;
        goto err_out;
    }

    pdata = kzalloc(sizeof(*pdata) + nbuttons * (sizeof *button),
            GFP_KERNEL);
    if (!pdata) {
        error = -ENOMEM;
        goto err_out;
    }

    pdata->buttons = (struct gpio_keys_button *)(pdata + 1);
    pdata->nbuttons = nbuttons;

    pdata->rep = !!of_get_property(node, "autorepeat", NULL);

    i = 0;
    for_each_child_of_node(node, pp) {
        enum of_gpio_flags flags;

        if (!of_find_property(pp, "gpios", NULL)) {
            pdata->nbuttons--;
            dev_warn(dev, "Found button without gpios\n");
            continue;
        }

        button = &pdata->buttons[i++];

        button->gpio = of_get_gpio_flags(pp, 0, &flags);
        button->active_low = flags & OF_GPIO_ACTIVE_LOW;

        if (of_property_read_u32(pp, "linux,code", &button->code)) {
            dev_err(dev, "Button without keycode: 0x%x\n",
                button->gpio);
            error = -EINVAL;
            goto err_free_pdata;
        }

        button->desc = of_get_property(pp, "label", NULL);

        if (of_property_read_u32(pp, "linux,input-type", &button->type))
            button->type = EV_KEY;

        button->wakeup = !!of_get_property(pp, "gpio-key,wakeup", NULL);

        if (of_property_read_u32(pp, "debounce-interval",
                     &button->debounce_interval))
            button->debounce_interval = 5;
    }

    if (pdata->nbuttons == 0) {
        error = -EINVAL;
        goto err_free_pdata;
    }

    return pdata;

err_free_pdata:
    kfree(pdata);
err_out:
    return ERR_PTR(error);
}

static struct of_device_id gpio_keys_of_match[] = {
    { .compatible = "gpio-keys", },
    { },
};
MODULE_DEVICE_TABLE(of, gpio_keys_of_match);

#else

static inline struct gpio_keys_platform_data *
gpio_keys_get_devtree_pdata(struct device *dev)
{
    return ERR_PTR(-ENODEV);
}

#endif

static void gpio_remove_key(struct gpio_button_data *bdata)
{
    free_irq(bdata->irq, bdata);
    if (bdata->timer_debounce)
        del_timer_sync(&bdata->timer);
    cancel_work_sync(&bdata->work);
    if (gpio_is_valid(bdata->button->gpio))
        gpio_free(bdata->button->gpio);
}

static int __devinit gpio_keys_probe(struct platform_device *pdev)
{
    struct device *dev = &pdev->dev;
    const struct gpio_keys_platform_data *pdata = dev_get_platdata(dev);
    struct gpio_keys_drvdata *ddata;
    struct input_dev *input;
    int i, error;
    int wakeup = 0;

    if (!pdata) {
        pdata = gpio_keys_get_devtree_pdata(dev);
        if (IS_ERR(pdata))
            return PTR_ERR(pdata);
    }

    ddata = kzalloc(sizeof(struct gpio_keys_drvdata) +
            pdata->nbuttons * sizeof(struct gpio_button_data),
            GFP_KERNEL);
    input = input_allocate_device();
    if (!ddata || !input) {
        dev_err(dev, "failed to allocate state\n");
        error = -ENOMEM;
        goto fail1;
    }

    ddata->pdata = pdata;
    ddata->input = input;
    mutex_init(&ddata->disable_lock);

    platform_set_drvdata(pdev, ddata);
    input_set_drvdata(input, ddata);

    input->name = pdata->name ? : pdev->name;
    input->phys = "gpio-keys/input0";
    input->dev.parent = &pdev->dev;
    input->open = gpio_keys_open;
    input->close = gpio_keys_close;

    input->id.bustype = BUS_HOST;
    input->id.vendor = 0x0001;
    input->id.product = 0x0001;
    input->id.version = 0x0100;

    /* Enable auto repeat feature of Linux input subsystem */
    if (pdata->rep)
        __set_bit(EV_REP, input->evbit);

    for (i = 0; i < pdata->nbuttons; i++) {
        const struct gpio_keys_button *button = &pdata->buttons[i];
        struct gpio_button_data *bdata = &ddata->data[i];

        error = gpio_keys_setup_key(pdev, input, bdata, button);
        if (error)
            goto fail2;

        if (button->wakeup)
            wakeup = 1;
    }

    error = sysfs_create_group(&pdev->dev.kobj, &gpio_keys_attr_group);
    if (error) {
        dev_err(dev, "Unable to export keys/switches, error: %d\n",
            error);
        goto fail2;
    }

    error = input_register_device(input);
    if (error) {
        dev_err(dev, "Unable to register input device, error: %d\n",
            error);
        goto fail3;
    }

    /* get current state of buttons that are connected to GPIOs */
    for (i = 0; i < pdata->nbuttons; i++) {
        struct gpio_button_data *bdata = &ddata->data[i];
        if (gpio_is_valid(bdata->button->gpio))
            gpio_keys_gpio_report_event(bdata);
    }
    input_sync(input);

    device_init_wakeup(&pdev->dev, wakeup);

    return 0;

 fail3:
    sysfs_remove_group(&pdev->dev.kobj, &gpio_keys_attr_group);
 fail2:
    while (--i >= 0)
        gpio_remove_key(&ddata->data[i]);

    platform_set_drvdata(pdev, NULL);
 fail1:
    input_free_device(input);
    kfree(ddata);
    /* If we have no platform data, we allocated pdata dynamically. */
    if (!dev_get_platdata(&pdev->dev))
        kfree(pdata);

    return error;
}

static int __devexit gpio_keys_remove(struct platform_device *pdev)
{
    struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);
    struct input_dev *input = ddata->input;
    int i;

    sysfs_remove_group(&pdev->dev.kobj, &gpio_keys_attr_group);

    device_init_wakeup(&pdev->dev, 0);

    for (i = 0; i < ddata->pdata->nbuttons; i++)
        gpio_remove_key(&ddata->data[i]);

    input_unregister_device(input);

    /* If we have no platform data, we allocated pdata dynamically. */
    if (!dev_get_platdata(&pdev->dev))
        kfree(ddata->pdata);

    kfree(ddata);

    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int gpio_keys_suspend(struct device *dev)
{
    struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
    int i;

    if (device_may_wakeup(dev)) {
        for (i = 0; i < ddata->pdata->nbuttons; i++) {
            struct gpio_button_data *bdata = &ddata->data[i];
            if (bdata->button->wakeup)
                enable_irq_wake(bdata->irq);
        }
    }

    return 0;
}

static int gpio_keys_resume(struct device *dev)
{
    struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
    int i;

    for (i = 0; i < ddata->pdata->nbuttons; i++) {
        struct gpio_button_data *bdata = &ddata->data[i];
        if (bdata->button->wakeup && device_may_wakeup(dev))
            disable_irq_wake(bdata->irq);

        if (gpio_is_valid(bdata->button->gpio))
            gpio_keys_gpio_report_event(bdata);
    }
    input_sync(ddata->input);

    return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(gpio_keys_pm_ops, gpio_keys_suspend, gpio_keys_resume);

static struct platform_driver gpio_keys_device_driver = {
    .probe      = gpio_keys_probe,
    .remove     = __devexit_p(gpio_keys_remove),
    .driver     = {
        .name   = "gpio-keys",
        .owner  = THIS_MODULE,
        .pm = &gpio_keys_pm_ops,
        .of_match_table = of_match_ptr(gpio_keys_of_match),
    }
};

static int __init gpio_keys_init(void)
{
    return platform_driver_register(&gpio_keys_device_driver);
}

static void __exit gpio_keys_exit(void)
{
    platform_driver_unregister(&gpio_keys_device_driver);
}

late_initcall(gpio_keys_init);
module_exit(gpio_keys_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Phil Blundell <[email protected]>");
MODULE_DESCRIPTION("Keyboard driver for GPIOs");
MODULE_ALIAS("platform:gpio-keys");