/*
 *  GPIO driven matrix keyboard driver
 *
 *  Copyright (c) 2008 Marek Vasut <marek.vasut@gmail.com>
 *
 *  Based on corgikbd.c
 *
 *  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/types.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/input/matrix_keypad.h>

struct matrix_keypad {
        const struct matrix_keypad_platform_data *pdata;
        struct input_dev *input_dev;
        unsigned short *keycodes;
        unsigned int row_shift;

        uint32_t last_key_state[MATRIX_MAX_COLS];
        struct delayed_work work;
        bool scan_pending;
        bool stopped;
        spinlock_t lock;
};

/*
 * NOTE: normally the GPIO has to be put into HiZ when de-activated to cause
 * minmal side effect when scanning other columns, here it is configured to
 * be input, and it should work on most platforms.
 */
static void __activate_col(const struct matrix_keypad_platform_data *pdata,
                           int col, bool on)
{
        bool level_on = !pdata->active_low;

        if (on) {
                gpio_direction_output(pdata->col_gpios[col], level_on);
        } else {
                gpio_set_value_cansleep(pdata->col_gpios[col], !level_on);
                gpio_direction_input(pdata->col_gpios[col]);
        }
}

static void activate_col(const struct matrix_keypad_platform_data *pdata,
                         int col, bool on)
{
        __activate_col(pdata, col, on);

        if (on && pdata->col_scan_delay_us)
                udelay(pdata->col_scan_delay_us);
}

static void activate_all_cols(const struct matrix_keypad_platform_data *pdata,
                              bool on)
{
        int col;

        for (col = 0; col < pdata->num_col_gpios; col++)
                __activate_col(pdata, col, on);
}

static bool row_asserted(const struct matrix_keypad_platform_data *pdata,
                         int row)
{
        return gpio_get_value_cansleep(pdata->row_gpios[row]) ?
                        !pdata->active_low : pdata->active_low;
}

static void enable_row_irqs(struct matrix_keypad *keypad)
{
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        int i;

        for (i = 0; i < pdata->num_row_gpios; i++)
                enable_irq(gpio_to_irq(pdata->row_gpios[i]));
}

static void disable_row_irqs(struct matrix_keypad *keypad)
{
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        int i;

        for (i = 0; i < pdata->num_row_gpios; i++)
                disable_irq_nosync(gpio_to_irq(pdata->row_gpios[i]));
}

/*
 * This gets the keys from keyboard and reports it to input subsystem
 */
static void matrix_keypad_scan(struct work_struct *work)
{
        struct matrix_keypad *keypad =
                container_of(work, struct matrix_keypad, work.work);
        struct input_dev *input_dev = keypad->input_dev;
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        uint32_t new_state[MATRIX_MAX_COLS];
        int row, col, code;

        /* de-activate all columns for scanning */
        activate_all_cols(pdata, false);

        memset(new_state, 0, sizeof(new_state));

        /* assert each column and read the row status out */
        for (col = 0; col < pdata->num_col_gpios; col++) {

                activate_col(pdata, col, true);

                for (row = 0; row < pdata->num_row_gpios; row++)
                        new_state[col] |=
                                row_asserted(pdata, row) ? (1 << row) : 0;

                activate_col(pdata, col, false);
        }

        for (col = 0; col < pdata->num_col_gpios; col++) {
                uint32_t bits_changed;

                bits_changed = keypad->last_key_state[col] ^ new_state[col];
                if (bits_changed == 0)
                        continue;

                for (row = 0; row < pdata->num_row_gpios; row++) {
                        if ((bits_changed & (1 << row)) == 0)
                                continue;

                        code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
                        input_event(input_dev, EV_MSC, MSC_SCAN, code);
                        input_report_key(input_dev,
                                         keypad->keycodes[code],
                                         new_state[col] & (1 << row));
                }
        }
        input_sync(input_dev);

        memcpy(keypad->last_key_state, new_state, sizeof(new_state));

        activate_all_cols(pdata, true);

        /* Enable IRQs again */
        spin_lock_irq(&keypad->lock);
        keypad->scan_pending = false;
        enable_row_irqs(keypad);
        spin_unlock_irq(&keypad->lock);
}

static irqreturn_t matrix_keypad_interrupt(int irq, void *id)
{
        struct matrix_keypad *keypad = id;
        unsigned long flags;

        spin_lock_irqsave(&keypad->lock, flags);

        /*
         * See if another IRQ beaten us to it and scheduled the
         * scan already. In that case we should not try to
         * disable IRQs again.
         */
        if (unlikely(keypad->scan_pending || keypad->stopped))
                goto out;

        disable_row_irqs(keypad);
        keypad->scan_pending = true;
        schedule_delayed_work(&keypad->work,
                msecs_to_jiffies(keypad->pdata->debounce_ms));

out:
        spin_unlock_irqrestore(&keypad->lock, flags);
        return IRQ_HANDLED;
}

static int matrix_keypad_start(struct input_dev *dev)
{
        struct matrix_keypad *keypad = input_get_drvdata(dev);

        keypad->stopped = false;
        mb();

        /*
         * Schedule an immediate key scan to capture current key state;
         * columns will be activated and IRQs be enabled after the scan.
         */
        schedule_delayed_work(&keypad->work, 0);

        return 0;
}

static void matrix_keypad_stop(struct input_dev *dev)
{
        struct matrix_keypad *keypad = input_get_drvdata(dev);

        keypad->stopped = true;
        mb();
        flush_work(&keypad->work.work);
        /*
         * matrix_keypad_scan() will leave IRQs enabled;
         * we should disable them now.
         */
        disable_row_irqs(keypad);
}

#ifdef CONFIG_PM
static int matrix_keypad_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct matrix_keypad *keypad = platform_get_drvdata(pdev);
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        int i;

        matrix_keypad_stop(keypad->input_dev);

        if (device_may_wakeup(&pdev->dev))
                for (i = 0; i < pdata->num_row_gpios; i++)
                        enable_irq_wake(gpio_to_irq(pdata->row_gpios[i]));

        return 0;
}

static int matrix_keypad_resume(struct platform_device *pdev)
{
        struct matrix_keypad *keypad = platform_get_drvdata(pdev);
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        int i;

        if (device_may_wakeup(&pdev->dev))
                for (i = 0; i < pdata->num_row_gpios; i++)
                        disable_irq_wake(gpio_to_irq(pdata->row_gpios[i]));

        matrix_keypad_start(keypad->input_dev);

        return 0;
}
#else
#define matrix_keypad_suspend   NULL
#define matrix_keypad_resume    NULL
#endif

static int __devinit init_matrix_gpio(struct platform_device *pdev,
                                        struct matrix_keypad *keypad)
{
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        int i, err = -EINVAL;

        /* initialized strobe lines as outputs, activated */
        for (i = 0; i < pdata->num_col_gpios; i++) {
                err = gpio_request(pdata->col_gpios[i], "matrix_kbd_col");
                if (err) {
                        dev_err(&pdev->dev,
                                "failed to request GPIO%d for COL%d\n",
                                pdata->col_gpios[i], i);
                        goto err_free_cols;
                }

                gpio_direction_output(pdata->col_gpios[i], !pdata->active_low);
        }

        for (i = 0; i < pdata->num_row_gpios; i++) {
                err = gpio_request(pdata->row_gpios[i], "matrix_kbd_row");
                if (err) {
                        dev_err(&pdev->dev,
                                "failed to request GPIO%d for ROW%d\n",
                                pdata->row_gpios[i], i);
                        goto err_free_rows;
                }

                gpio_direction_input(pdata->row_gpios[i]);
        }

        for (i = 0; i < pdata->num_row_gpios; i++) {
                err = request_irq(gpio_to_irq(pdata->row_gpios[i]),
                                matrix_keypad_interrupt,
                                IRQF_DISABLED |
                                IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
                                "matrix-keypad", keypad);
                if (err) {
                        dev_err(&pdev->dev,
                                "Unable to acquire interrupt for GPIO line %i\n",
                                pdata->row_gpios[i]);
                        goto err_free_irqs;
                }
        }

        /* initialized as disabled - enabled by input->open */
        disable_row_irqs(keypad);
        return 0;

err_free_irqs:
        while (--i >= 0)
                free_irq(gpio_to_irq(pdata->row_gpios[i]), keypad);
        i = pdata->num_row_gpios;
err_free_rows:
        while (--i >= 0)
                gpio_free(pdata->row_gpios[i]);
        i = pdata->num_col_gpios;
err_free_cols:
        while (--i >= 0)
                gpio_free(pdata->col_gpios[i]);

        return err;
}

static int __devinit matrix_keypad_probe(struct platform_device *pdev)
{
        const struct matrix_keypad_platform_data *pdata;
        const struct matrix_keymap_data *keymap_data;
        struct matrix_keypad *keypad;
        struct input_dev *input_dev;
        unsigned short *keycodes;
        unsigned int row_shift;
        int err;

        pdata = pdev->dev.platform_data;
        if (!pdata) {
                dev_err(&pdev->dev, "no platform data defined\n");
                return -EINVAL;
        }

        keymap_data = pdata->keymap_data;
        if (!keymap_data) {
                dev_err(&pdev->dev, "no keymap data defined\n");
                return -EINVAL;
        }

        row_shift = get_count_order(pdata->num_col_gpios);

        keypad = kzalloc(sizeof(struct matrix_keypad), GFP_KERNEL);
        keycodes = kzalloc((pdata->num_row_gpios << row_shift) *
                                sizeof(*keycodes),
                           GFP_KERNEL);
        input_dev = input_allocate_device();
        if (!keypad || !keycodes || !input_dev) {
                err = -ENOMEM;
                goto err_free_mem;
        }

        keypad->input_dev = input_dev;
        keypad->pdata = pdata;
        keypad->keycodes = keycodes;
        keypad->row_shift = row_shift;
        keypad->stopped = true;
        INIT_DELAYED_WORK(&keypad->work, matrix_keypad_scan);
        spin_lock_init(&keypad->lock);

        input_dev->name         = pdev->name;
        input_dev->id.bustype   = BUS_HOST;
        input_dev->dev.parent   = &pdev->dev;
        input_dev->evbit[0]     = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
        input_dev->open         = matrix_keypad_start;
        input_dev->close        = matrix_keypad_stop;

        input_dev->keycode      = keycodes;
        input_dev->keycodesize  = sizeof(*keycodes);
        input_dev->keycodemax   = pdata->num_row_gpios << row_shift;

        matrix_keypad_build_keymap(keymap_data, row_shift,
                                   input_dev->keycode, input_dev->keybit);

        input_set_capability(input_dev, EV_MSC, MSC_SCAN);
        input_set_drvdata(input_dev, keypad);

        err = init_matrix_gpio(pdev, keypad);
        if (err)
                goto err_free_mem;

        err = input_register_device(keypad->input_dev);
        if (err)
                goto err_free_mem;

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

        return 0;

err_free_mem:
        input_free_device(input_dev);
        kfree(keycodes);
        kfree(keypad);
        return err;
}

static int __devexit matrix_keypad_remove(struct platform_device *pdev)
{
        struct matrix_keypad *keypad = platform_get_drvdata(pdev);
        const struct matrix_keypad_platform_data *pdata = keypad->pdata;
        int i;

        device_init_wakeup(&pdev->dev, 0);

        for (i = 0; i < pdata->num_row_gpios; i++) {
                free_irq(gpio_to_irq(pdata->row_gpios[i]), keypad);
                gpio_free(pdata->row_gpios[i]);
        }

        for (i = 0; i < pdata->num_col_gpios; i++)
                gpio_free(pdata->col_gpios[i]);

        input_unregister_device(keypad->input_dev);
        platform_set_drvdata(pdev, NULL);
        kfree(keypad->keycodes);
        kfree(keypad);

        return 0;
}

static struct platform_driver matrix_keypad_driver = {
        .probe          = matrix_keypad_probe,
        .remove         = __devexit_p(matrix_keypad_remove),
        .suspend        = matrix_keypad_suspend,
        .resume         = matrix_keypad_resume,
        .driver         = {
                .name   = "matrix-keypad",
                .owner  = THIS_MODULE,
        },
};

static int __init matrix_keypad_init(void)
{
        return platform_driver_register(&matrix_keypad_driver);
}

static void __exit matrix_keypad_exit(void)
{
        platform_driver_unregister(&matrix_keypad_driver);
}

module_init(matrix_keypad_init);
module_exit(matrix_keypad_exit);

MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
MODULE_DESCRIPTION("GPIO Driven Matrix Keypad Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:matrix-keypad");