// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for keys on GPIO lines capable of generating interrupts.
 *
 * Copyright 2005 Phil Blundell
 * Copyright 2010, 2011 David Jander <david@protonic.nl>
 */

#include <linux/module.h>

#include <linux/hrtimer.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/gpio/consumer.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/spinlock.h>
#include <dt-bindings/input/gpio-keys.h>

struct gpio_button_data {
        const struct gpio_keys_button *button;
        struct input_dev *input;
        struct gpio_desc *gpiod;

        unsigned short *code;

        struct hrtimer release_timer;
        unsigned int release_delay;     /* in msecs, for IRQ-only buttons */

        struct delayed_work work;
        struct hrtimer debounce_timer;
        unsigned int software_debounce; /* in msecs, for GPIO-driven buttons */

        unsigned int irq;
        unsigned int wakeup_trigger_type;
        spinlock_t lock;
        bool disabled;
        bool key_pressed;
        bool suspended;
        bool debounce_use_hrtimer;
};

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

/*
 * 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.
 */

/**
 * get_n_events_by_type() - returns maximum number of events per @type
 * @type: type of button (%EV_KEY, %EV_SW)
 *
 * Return value of this function can be used to allocate bitmap
 * large enough to hold all bits for given type.
 */
static int get_n_events_by_type(int type)
{
        BUG_ON(type != EV_SW && type != EV_KEY);

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

/**
 * get_bm_events_by_type() - returns bitmap of supported events per @type
 * @dev: input device from which bitmap is retrieved
 * @type: type of button (%EV_KEY, %EV_SW)
 *
 * Return value of this function can be used to allocate bitmap
 * large enough to hold all bits for given type.
 */
static const unsigned long *get_bm_events_by_type(struct input_dev *dev,
                                                  int type)
{
        BUG_ON(type != EV_SW && type != EV_KEY);

        return (type == EV_KEY) ? dev->keybit : dev->swbit;
}

static void gpio_keys_quiesce_key(void *data)
{
        struct gpio_button_data *bdata = data;

        if (!bdata->gpiod)
                hrtimer_cancel(&bdata->release_timer);
        if (bdata->debounce_use_hrtimer)
                hrtimer_cancel(&bdata->debounce_timer);
        else
                cancel_delayed_work_sync(&bdata->work);
}

/**
 * gpio_keys_disable_button() - disables given GPIO button
 * @bdata: button data for button to be disabled
 *
 * Disables button pointed by @bdata. This is done by masking
 * IRQ line. After this function is called, button won't generate
 * input events anymore. Note that one can only disable buttons
 * that don't share IRQs.
 *
 * Make sure that @bdata->disable_lock is locked when entering
 * this function to avoid races when concurrent threads are
 * disabling buttons at the same time.
 */
static void gpio_keys_disable_button(struct gpio_button_data *bdata)
{
        if (!bdata->disabled) {
                /*
                 * Disable IRQ and associated timer/work structure.
                 */
                disable_irq(bdata->irq);
                gpio_keys_quiesce_key(bdata);
                bdata->disabled = true;
        }
}

/**
 * gpio_keys_enable_button() - enables given GPIO button
 * @bdata: button data for button to be disabled
 *
 * Enables given button pointed by @bdata.
 *
 * Make sure that @bdata->disable_lock is locked when entering
 * this function to avoid races with concurrent threads trying
 * to enable the same button at the same time.
 */
static void gpio_keys_enable_button(struct gpio_button_data *bdata)
{
        if (bdata->disabled) {
                enable_irq(bdata->irq);
                bdata->disabled = false;
        }
}

/**
 * gpio_keys_attr_show_helper() - fill in stringified bitmap of buttons
 * @ddata: pointer to drvdata
 * @buf: buffer where stringified bitmap is written
 * @type: button type (%EV_KEY, %EV_SW)
 * @only_disabled: does caller want only those buttons that are
 *                 currently disabled or all buttons that can be
 *                 disabled
 *
 * This function writes buttons that can be disabled to @buf. If
 * @only_disabled is true, then @buf contains only those buttons
 * that are currently disabled. Returns 0 on success or negative
 * errno on failure.
 */
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 = bitmap_zalloc(n_events, 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->code, bits);
        }

        ret = scnprintf(buf, PAGE_SIZE - 1, "%*pbl", n_events, bits);
        buf[ret++] = '\n';
        buf[ret] = '\0';

        bitmap_free(bits);

        return ret;
}

/**
 * gpio_keys_attr_store_helper() - enable/disable buttons based on given bitmap
 * @ddata: pointer to drvdata
 * @buf: buffer from userspace that contains stringified bitmap
 * @type: button type (%EV_KEY, %EV_SW)
 *
 * This function parses stringified bitmap from @buf and disables/enables
 * GPIO buttons accordingly. Returns 0 on success and negative error
 * on failure.
 */
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);
        const unsigned long *bitmap = get_bm_events_by_type(ddata->input, type);
        unsigned long *bits;
        ssize_t error;
        int i;

        bits = bitmap_zalloc(n_events, GFP_KERNEL);
        if (!bits)
                return -ENOMEM;

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

        /* First validate */
        if (!bitmap_subset(bits, bitmap, n_events)) {
                error = -EINVAL;
                goto out;
        }

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

        mutex_unlock(&ddata->disable_lock);

out:
        bitmap_free(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,
};
ATTRIBUTE_GROUPS(gpio_keys);

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;

        state = bdata->debounce_use_hrtimer ?
                        gpiod_get_value(bdata->gpiod) :
                        gpiod_get_value_cansleep(bdata->gpiod);
        if (state < 0) {
                dev_err(input->dev.parent,
                        "failed to get gpio state: %d\n", state);
                return;
        }

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

static void gpio_keys_debounce_event(struct gpio_button_data *bdata)
{
        gpio_keys_gpio_report_event(bdata);
        input_sync(bdata->input);

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

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

        gpio_keys_debounce_event(bdata);
}

static enum hrtimer_restart gpio_keys_debounce_timer(struct hrtimer *t)
{
        struct gpio_button_data *bdata =
                container_of(t, struct gpio_button_data, debounce_timer);

        gpio_keys_debounce_event(bdata);

        return HRTIMER_NORESTART;
}

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) {
                const struct gpio_keys_button *button = bdata->button;

                pm_stay_awake(bdata->input->dev.parent);
                if (bdata->suspended  &&
                    (button->type == 0 || button->type == EV_KEY)) {
                        /*
                         * Simulate wakeup key press in case the key has
                         * already released by the time we got interrupt
                         * handler to run.
                         */
                        input_report_key(bdata->input, button->code, 1);
                }
        }

        if (bdata->debounce_use_hrtimer) {
                hrtimer_start(&bdata->debounce_timer,
                              ms_to_ktime(bdata->software_debounce),
                              HRTIMER_MODE_REL);
        } else {
                mod_delayed_work(system_wq,
                                 &bdata->work,
                                 msecs_to_jiffies(bdata->software_debounce));
        }

        return IRQ_HANDLED;
}

static enum hrtimer_restart gpio_keys_irq_timer(struct hrtimer *t)
{
        struct gpio_button_data *bdata = container_of(t,
                                                      struct gpio_button_data,
                                                      release_timer);
        struct input_dev *input = bdata->input;

        if (bdata->key_pressed) {
                input_event(input, EV_KEY, *bdata->code, 0);
                input_sync(input);
                bdata->key_pressed = false;
        }

        return HRTIMER_NORESTART;
}

static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id)
{
        struct gpio_button_data *bdata = dev_id;
        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, *bdata->code, 1);
                input_sync(input);

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

                bdata->key_pressed = true;
        }

        if (bdata->release_delay)
                hrtimer_start(&bdata->release_timer,
                              ms_to_ktime(bdata->release_delay),
                              HRTIMER_MODE_REL_HARD);
out:
        spin_unlock_irqrestore(&bdata->lock, flags);
        return IRQ_HANDLED;
}

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

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

        if (child) {
                bdata->gpiod = devm_fwnode_gpiod_get(dev, child,
                                                     NULL, GPIOD_IN, desc);
                if (IS_ERR(bdata->gpiod)) {
                        error = PTR_ERR(bdata->gpiod);
                        if (error == -ENOENT) {
                                /*
                                 * GPIO is optional, we may be dealing with
                                 * purely interrupt-driven setup.
                                 */
                                bdata->gpiod = NULL;
                        } else {
                                if (error != -EPROBE_DEFER)
                                        dev_err(dev, "failed to get gpio: %d\n",
                                                error);
                                return error;
                        }
                }
        } else if (gpio_is_valid(button->gpio)) {
                /*
                 * Legacy GPIO number, so request the GPIO here and
                 * convert it to descriptor.
                 */
                unsigned flags = GPIOF_IN;

                if (button->active_low)
                        flags |= GPIOF_ACTIVE_LOW;

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

                bdata->gpiod = gpio_to_desc(button->gpio);
                if (!bdata->gpiod)
                        return -EINVAL;
        }

        if (bdata->gpiod) {
                bool active_low = gpiod_is_active_low(bdata->gpiod);

                if (button->debounce_interval) {
                        error = gpiod_set_debounce(bdata->gpiod,
                                        button->debounce_interval * 1000);
                        /* use timer if gpiolib doesn't provide debounce */
                        if (error < 0)
                                bdata->software_debounce =
                                                button->debounce_interval;

                        /*
                         * If reading the GPIO won't sleep, we can use a
                         * hrtimer instead of a standard timer for the software
                         * debounce, to reduce the latency as much as possible.
                         */
                        bdata->debounce_use_hrtimer =
                                        !gpiod_cansleep(bdata->gpiod);
                }

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

                INIT_DELAYED_WORK(&bdata->work, gpio_keys_gpio_work_func);

                hrtimer_init(&bdata->debounce_timer,
                             CLOCK_REALTIME, HRTIMER_MODE_REL);
                bdata->debounce_timer.function = gpio_keys_debounce_timer;

                isr = gpio_keys_gpio_isr;
                irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;

                switch (button->wakeup_event_action) {
                case EV_ACT_ASSERTED:
                        bdata->wakeup_trigger_type = active_low ?
                                IRQ_TYPE_EDGE_FALLING : IRQ_TYPE_EDGE_RISING;
                        break;
                case EV_ACT_DEASSERTED:
                        bdata->wakeup_trigger_type = active_low ?
                                IRQ_TYPE_EDGE_RISING : IRQ_TYPE_EDGE_FALLING;
                        break;
                case EV_ACT_ANY:
                default:
                        /*
                         * For other cases, we are OK letting suspend/resume
                         * not reconfigure the trigger type.
                         */
                        break;
                }
        } else {
                if (!button->irq) {
                        dev_err(dev, "Found button without gpio or irq\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->release_delay = button->debounce_interval;
                hrtimer_init(&bdata->release_timer,
                             CLOCK_REALTIME, HRTIMER_MODE_REL_HARD);
                bdata->release_timer.function = gpio_keys_irq_timer;

                isr = gpio_keys_irq_isr;
                irqflags = 0;

                /*
                 * For IRQ buttons, there is no interrupt for release.
                 * So we don't need to reconfigure the trigger type for wakeup.
                 */
        }

        bdata->code = &ddata->keymap[idx];
        *bdata->code = button->code;
        input_set_capability(input, button->type ?: EV_KEY, *bdata->code);

        /*
         * Install custom action to cancel release timer and
         * workqueue item.
         */
        error = devm_add_action(dev, gpio_keys_quiesce_key, bdata);
        if (error) {
                dev_err(dev, "failed to register quiesce action, error: %d\n",
                        error);
                return error;
        }

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

        return 0;
}

static void gpio_keys_report_state(struct gpio_keys_drvdata *ddata)
{
        struct input_dev *input = ddata->input;
        int i;

        for (i = 0; i < ddata->pdata->nbuttons; i++) {
                struct gpio_button_data *bdata = &ddata->data[i];
                if (bdata->gpiod)
                        gpio_keys_gpio_report_event(bdata);
        }
        input_sync(input);
}

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;
        int error;

        if (pdata->enable) {
                error = pdata->enable(input->dev.parent);
                if (error)
                        return error;
        }

        /* Report current state of buttons that are connected to GPIOs */
        gpio_keys_report_state(ddata);

        return 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
 */

/*
 * Translate properties into platform_data
 */
static struct gpio_keys_platform_data *
gpio_keys_get_devtree_pdata(struct device *dev)
{
        struct gpio_keys_platform_data *pdata;
        struct gpio_keys_button *button;
        struct fwnode_handle *child;
        int nbuttons;

        nbuttons = device_get_child_node_count(dev);
        if (nbuttons == 0)
                return ERR_PTR(-ENODEV);

        pdata = devm_kzalloc(dev,
                             sizeof(*pdata) + nbuttons * sizeof(*button),
                             GFP_KERNEL);
        if (!pdata)
                return ERR_PTR(-ENOMEM);

        button = (struct gpio_keys_button *)(pdata + 1);

        pdata->buttons = button;
        pdata->nbuttons = nbuttons;

        pdata->rep = device_property_read_bool(dev, "autorepeat");

        device_property_read_string(dev, "label", &pdata->name);

        device_for_each_child_node(dev, child) {
                if (is_of_node(child))
                        button->irq =
                                irq_of_parse_and_map(to_of_node(child), 0);

                if (fwnode_property_read_u32(child, "linux,code",
                                             &button->code)) {
                        dev_err(dev, "Button without keycode\n");
                        fwnode_handle_put(child);
                        return ERR_PTR(-EINVAL);
                }

                fwnode_property_read_string(child, "label", &button->desc);

                if (fwnode_property_read_u32(child, "linux,input-type",
                                             &button->type))
                        button->type = EV_KEY;

                button->wakeup =
                        fwnode_property_read_bool(child, "wakeup-source") ||
                        /* legacy name */
                        fwnode_property_read_bool(child, "gpio-key,wakeup");

                fwnode_property_read_u32(child, "wakeup-event-action",
                                         &button->wakeup_event_action);

                button->can_disable =
                        fwnode_property_read_bool(child, "linux,can-disable");

                if (fwnode_property_read_u32(child, "debounce-interval",
                                         &button->debounce_interval))
                        button->debounce_interval = 5;

                button++;
        }

        return pdata;
}

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

static int gpio_keys_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        const struct gpio_keys_platform_data *pdata = dev_get_platdata(dev);
        struct fwnode_handle *child = NULL;
        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 = devm_kzalloc(dev, struct_size(ddata, data, pdata->nbuttons),
                             GFP_KERNEL);
        if (!ddata) {
                dev_err(dev, "failed to allocate state\n");
                return -ENOMEM;
        }

        ddata->keymap = devm_kcalloc(dev,
                                     pdata->nbuttons, sizeof(ddata->keymap[0]),
                                     GFP_KERNEL);
        if (!ddata->keymap)
                return -ENOMEM;

        input = devm_input_allocate_device(dev);
        if (!input) {
                dev_err(dev, "failed to allocate input device\n");
                return -ENOMEM;
        }

        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 = 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;

        input->keycode = ddata->keymap;
        input->keycodesize = sizeof(ddata->keymap[0]);
        input->keycodemax = pdata->nbuttons;

        /* 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];

                if (!dev_get_platdata(dev)) {
                        child = device_get_next_child_node(dev, child);
                        if (!child) {
                                dev_err(dev,
                                        "missing child device node for entry %d\n",
                                        i);
                                return -EINVAL;
                        }
                }

                error = gpio_keys_setup_key(pdev, input, ddata,
                                            button, i, child);
                if (error) {
                        fwnode_handle_put(child);
                        return error;
                }

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

        fwnode_handle_put(child);

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

        device_init_wakeup(dev, wakeup);

        return 0;
}

static int __maybe_unused
gpio_keys_button_enable_wakeup(struct gpio_button_data *bdata)
{
        int error;

        error = enable_irq_wake(bdata->irq);
        if (error) {
                dev_err(bdata->input->dev.parent,
                        "failed to configure IRQ %d as wakeup source: %d\n",
                        bdata->irq, error);
                return error;
        }

        if (bdata->wakeup_trigger_type) {
                error = irq_set_irq_type(bdata->irq,
                                         bdata->wakeup_trigger_type);
                if (error) {
                        dev_err(bdata->input->dev.parent,
                                "failed to set wakeup trigger %08x for IRQ %d: %d\n",
                                bdata->wakeup_trigger_type, bdata->irq, error);
                        disable_irq_wake(bdata->irq);
                        return error;
                }
        }

        return 0;
}

static void __maybe_unused
gpio_keys_button_disable_wakeup(struct gpio_button_data *bdata)
{
        int error;

        /*
         * The trigger type is always both edges for gpio-based keys and we do
         * not support changing wakeup trigger for interrupt-based keys.
         */
        if (bdata->wakeup_trigger_type) {
                error = irq_set_irq_type(bdata->irq, IRQ_TYPE_EDGE_BOTH);
                if (error)
                        dev_warn(bdata->input->dev.parent,
                                 "failed to restore interrupt trigger for IRQ %d: %d\n",
                                 bdata->irq, error);
        }

        error = disable_irq_wake(bdata->irq);
        if (error)
                dev_warn(bdata->input->dev.parent,
                         "failed to disable IRQ %d as wake source: %d\n",
                         bdata->irq, error);
}

static int __maybe_unused
gpio_keys_enable_wakeup(struct gpio_keys_drvdata *ddata)
{
        struct gpio_button_data *bdata;
        int error;
        int i;

        for (i = 0; i < ddata->pdata->nbuttons; i++) {
                bdata = &ddata->data[i];
                if (bdata->button->wakeup) {
                        error = gpio_keys_button_enable_wakeup(bdata);
                        if (error)
                                goto err_out;
                }
                bdata->suspended = true;
        }

        return 0;

err_out:
        while (i--) {
                bdata = &ddata->data[i];
                if (bdata->button->wakeup)
                        gpio_keys_button_disable_wakeup(bdata);
                bdata->suspended = false;
        }

        return error;
}

static void __maybe_unused
gpio_keys_disable_wakeup(struct gpio_keys_drvdata *ddata)
{
        struct gpio_button_data *bdata;
        int i;

        for (i = 0; i < ddata->pdata->nbuttons; i++) {
                bdata = &ddata->data[i];
                bdata->suspended = false;
                if (irqd_is_wakeup_set(irq_get_irq_data(bdata->irq)))
                        gpio_keys_button_disable_wakeup(bdata);
        }
}

static int __maybe_unused gpio_keys_suspend(struct device *dev)
{
        struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
        struct input_dev *input = ddata->input;
        int error;

        if (device_may_wakeup(dev)) {
                error = gpio_keys_enable_wakeup(ddata);
                if (error)
                        return error;
        } else {
                mutex_lock(&input->mutex);
                if (input_device_enabled(input))
                        gpio_keys_close(input);
                mutex_unlock(&input->mutex);
        }

        return 0;
}

static int __maybe_unused gpio_keys_resume(struct device *dev)
{
        struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
        struct input_dev *input = ddata->input;
        int error = 0;

        if (device_may_wakeup(dev)) {
                gpio_keys_disable_wakeup(ddata);
        } else {
                mutex_lock(&input->mutex);
                if (input_device_enabled(input))
                        error = gpio_keys_open(input);
                mutex_unlock(&input->mutex);
        }

        if (error)
                return error;

        gpio_keys_report_state(ddata);
        return 0;
}

static SIMPLE_DEV_PM_OPS(gpio_keys_pm_ops, gpio_keys_suspend, gpio_keys_resume);

static void gpio_keys_shutdown(struct platform_device *pdev)
{
        int ret;

        ret = gpio_keys_suspend(&pdev->dev);
        if (ret)
                dev_err(&pdev->dev, "failed to shutdown\n");
}

static struct platform_driver gpio_keys_device_driver = {
        .probe          = gpio_keys_probe,
        .shutdown       = gpio_keys_shutdown,
        .driver         = {
                .name   = "gpio-keys",
                .pm     = &gpio_keys_pm_ops,
                .of_match_table = gpio_keys_of_match,
                .dev_groups     = gpio_keys_groups,
        }
};

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 <pb@handhelds.org>");
MODULE_DESCRIPTION("Keyboard driver for GPIOs");
MODULE_ALIAS("platform:gpio-keys");