/*
 * Driver for keys on GPIO lines capable of generating interrupts.
 *
 * Copyright 2005 Phil Blundell
 * Copyright 2010, 2011 David Jander <david@protonic.nl>
 *
 * 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>

struct gpio_button_data {
        struct gpio_keys_button *button;
        struct input_dev *input;
        struct timer_list timer;
        struct work_struct work;
        int timer_debounce;     /* in msecs */
        bool disabled;
};

struct gpio_keys_drvdata {
        struct input_dev *input;
        struct mutex disable_lock;
        unsigned int n_buttons;
        int (*enable)(struct device *dev);
        void (*disable)(struct device *dev);
        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.
 */

/**
 * 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 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;
}

/**
 * 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 possible debouncing timer.
                 */
                disable_irq(gpio_to_irq(bdata->button->gpio));
                if (bdata->timer_debounce)
                        del_timer_sync(&bdata->timer);

                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(gpio_to_irq(bdata->button->gpio));
                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 = kcalloc(BITS_TO_LONGS(n_events), sizeof(*bits), GFP_KERNEL);
        if (!bits)
                return -ENOMEM;

        for (i = 0; i < ddata->n_buttons; 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;
}

/**
 * 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 accordinly. 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);
        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->n_buttons; 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->n_buttons; 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_report_event(struct gpio_button_data *bdata)
{
        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_work_func(struct work_struct *work)
{
        struct gpio_button_data *bdata =
                container_of(work, struct gpio_button_data, work);

        gpio_keys_report_event(bdata);
}

static void gpio_keys_timer(unsigned long _data)
{
        struct gpio_button_data *data = (struct gpio_button_data *)_data;

        schedule_work(&data->work);
}

static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
{
        struct gpio_button_data *bdata = dev_id;
        struct gpio_keys_button *button = bdata->button;

        BUG_ON(irq != gpio_to_irq(button->gpio));

        if (bdata->timer_debounce)
                mod_timer(&bdata->timer,
                        jiffies + msecs_to_jiffies(bdata->timer_debounce));
        else
                schedule_work(&bdata->work);

        return IRQ_HANDLED;
}

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

        setup_timer(&bdata->timer, gpio_keys_timer, (unsigned long)bdata);
        INIT_WORK(&bdata->work, gpio_keys_work_func);

        error = gpio_request(button->gpio, desc);
        if (error < 0) {
                dev_err(dev, "failed to request GPIO %d, error %d\n",
                        button->gpio, error);
                goto fail2;
        }

        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 fail3;
        }

        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 fail3;
        }

        irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
        /*
         * 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_threaded_irq(irq, NULL, gpio_keys_isr, irqflags, desc, bdata);
        if (error < 0) {
                dev_err(dev, "Unable to claim irq %d; error %d\n",
                        irq, error);
                goto fail3;
        }

        return 0;

fail3:
        gpio_free(button->gpio);
fail2:
        return error;
}

static int gpio_keys_open(struct input_dev *input)
{
        struct gpio_keys_drvdata *ddata = input_get_drvdata(input);

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

static void gpio_keys_close(struct input_dev *input)
{
        struct gpio_keys_drvdata *ddata = input_get_drvdata(input);

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

/*
 * Handlers for alternative sources of platform_data
 */
#ifdef CONFIG_OF
/*
 * Translate OpenFirmware node properties into platform_data
 */
static int gpio_keys_get_devtree_pdata(struct device *dev,
                            struct gpio_keys_platform_data *pdata)
{
        struct device_node *node, *pp;
        int i;
        struct gpio_keys_button *buttons;
        u32 reg;

        node = dev->of_node;
        if (node == NULL)
                return -ENODEV;

        memset(pdata, 0, sizeof *pdata);

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

        /* First count the subnodes */
        pdata->nbuttons = 0;
        pp = NULL;
        while ((pp = of_get_next_child(node, pp)))
                pdata->nbuttons++;

        if (pdata->nbuttons == 0)
                return -ENODEV;

        buttons = kzalloc(pdata->nbuttons * (sizeof *buttons), GFP_KERNEL);
        if (!buttons)
                return -ENOMEM;

        pp = NULL;
        i = 0;
        while ((pp = of_get_next_child(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;
                }
                buttons[i].gpio = of_get_gpio_flags(pp, 0, &flags);
                buttons[i].active_low = flags & OF_GPIO_ACTIVE_LOW;

                if (of_property_read_u32(pp, "linux,code", &reg)) {
                        dev_err(dev, "Button without keycode: 0x%x\n", buttons[i].gpio);
                        goto out_fail;
                }
                buttons[i].code = reg;

                buttons[i].desc = of_get_property(pp, "label", NULL);

                if (of_property_read_u32(pp, "linux,input-type", &reg) == 0)
                        buttons[i].type = reg;
                else
                        buttons[i].type = EV_KEY;

                buttons[i].wakeup = !!of_get_property(pp, "gpio-key,wakeup", NULL);

                if (of_property_read_u32(pp, "debounce-interval", &reg) == 0)
                        buttons[i].debounce_interval = reg;
                else
                        buttons[i].debounce_interval = 5;

                i++;
        }

        pdata->buttons = buttons;

        return 0;

out_fail:
        kfree(buttons);
        return -ENODEV;
}

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

#else

static int gpio_keys_get_devtree_pdata(struct device *dev,
                            struct gpio_keys_platform_data *altp)
{
        return -ENODEV;
}

#define gpio_keys_of_match NULL

#endif

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

        if (!pdata) {
                error = gpio_keys_get_devtree_pdata(dev, &alt_pdata);
                if (error)
                        return error;
                pdata = &alt_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->input = input;
        ddata->n_buttons = pdata->nbuttons;
        ddata->enable = pdata->enable;
        ddata->disable = pdata->disable;
        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++) {
                struct gpio_keys_button *button = &pdata->buttons[i];
                struct gpio_button_data *bdata = &ddata->data[i];
                unsigned int type = button->type ?: EV_KEY;

                bdata->input = input;
                bdata->button = button;

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

                if (button->wakeup)
                        wakeup = 1;

                input_set_capability(input, type, button->code);
        }

        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 */
        for (i = 0; i < pdata->nbuttons; i++)
                gpio_keys_report_event(&ddata->data[i]);
        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) {
                free_irq(gpio_to_irq(pdata->buttons[i].gpio), &ddata->data[i]);
                if (ddata->data[i].timer_debounce)
                        del_timer_sync(&ddata->data[i].timer);
                cancel_work_sync(&ddata->data[i].work);
                gpio_free(pdata->buttons[i].gpio);
        }

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

        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->n_buttons; i++) {
                int irq = gpio_to_irq(ddata->data[i].button->gpio);
                free_irq(irq, &ddata->data[i]);
                if (ddata->data[i].timer_debounce)
                        del_timer_sync(&ddata->data[i].timer);
                cancel_work_sync(&ddata->data[i].work);
                gpio_free(ddata->data[i].button->gpio);
        }

        input_unregister_device(input);

        /*
         * If we had no platform_data, we allocated buttons dynamically, and
         * must free them here. ddata->data[0].button is the pointer to the
         * beginning of the allocated array.
         */
        if (!pdev->dev.platform_data)
                kfree(ddata->data[0].button);

        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->n_buttons; i++) {
                        struct gpio_keys_button *button = ddata->data[i].button;
                        if (button->wakeup) {
                                int irq = gpio_to_irq(button->gpio);
                                enable_irq_wake(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->n_buttons; i++) {

                struct gpio_keys_button *button = ddata->data[i].button;
                if (button->wakeup && device_may_wakeup(dev)) {
                        int irq = gpio_to_irq(button->gpio);
                        disable_irq_wake(irq);
                }

                gpio_keys_report_event(&ddata->data[i]);
        }
        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 = 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 <pb@handhelds.org>");
MODULE_DESCRIPTION("Keyboard driver for GPIOs");
MODULE_ALIAS("platform:gpio-keys");