// SPDX-License-Identifier: GPL-2.0-only
/*
 *  GPIO driven matrix keyboard driver
 *
 *  Copyright (c) 2008 Marek Vasut <marek.vasut@gmail.com>
 *
 *  Based on corgikbd.c
 */

#include <linux/types.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.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>
#include <linux/slab.h>
#include <linux/of.h>

struct matrix_keypad {
        struct input_dev *input_dev;
        unsigned int row_shift;

        unsigned int col_scan_delay_us;
        unsigned int all_cols_on_delay_us;
        /* key debounce interval in milli-second */
        unsigned int debounce_ms;
        bool drive_inactive_cols;

        struct gpio_desc *row_gpios[MATRIX_MAX_ROWS];
        unsigned int num_row_gpios;

        struct gpio_desc *col_gpios[MATRIX_MAX_ROWS];
        unsigned int num_col_gpios;

        unsigned int row_irqs[MATRIX_MAX_ROWS];
        DECLARE_BITMAP(wakeup_enabled_irqs, MATRIX_MAX_ROWS);

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

/*
 * NOTE: If drive_inactive_cols is false, then the GPIO has to be put into
 * HiZ when de-activated to cause minmal side effect when scanning other
 * columns. In that case it is configured here to be input, otherwise it is
 * driven with the inactive value.
 */
static void __activate_col(struct matrix_keypad *keypad, int col, bool on)
{
        if (on) {
                gpiod_direction_output(keypad->col_gpios[col], 1);
        } else {
                gpiod_set_value_cansleep(keypad->col_gpios[col], 0);
                if (!keypad->drive_inactive_cols)
                        gpiod_direction_input(keypad->col_gpios[col]);
        }
}

static void activate_col(struct matrix_keypad *keypad, int col, bool on)
{
        __activate_col(keypad, col, on);

        if (on && keypad->col_scan_delay_us)
                fsleep(keypad->col_scan_delay_us);
}

static void activate_all_cols(struct matrix_keypad *keypad, bool on)
{
        int col;

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

        if (on && keypad->all_cols_on_delay_us)
                fsleep(keypad->all_cols_on_delay_us);
}

static bool row_asserted(struct matrix_keypad *keypad, int row)
{
        return gpiod_get_value_cansleep(keypad->row_gpios[row]);
}

static void enable_row_irqs(struct matrix_keypad *keypad)
{
        int i;

        for (i = 0; i < keypad->num_row_gpios; i++)
                enable_irq(keypad->row_irqs[i]);
}

static void disable_row_irqs(struct matrix_keypad *keypad)
{
        int i;

        for (i = 0; i < keypad->num_row_gpios; i++)
                disable_irq_nosync(keypad->row_irqs[i]);
}

static uint32_t read_row_state(struct matrix_keypad *keypad)
{
        int row;
        u32 row_state = 0;

        for (row = 0; row < keypad->num_row_gpios; row++)
                row_state |= row_asserted(keypad, row) ? BIT(row) : 0;
        return row_state;
}

/*
 * 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 unsigned short *keycodes = input_dev->keycode;
        uint32_t new_state[MATRIX_MAX_COLS];
        int row, col, code;
        u32 init_row_state, new_row_state;

        /* read initial row state to detect changes between scan */
        init_row_state = read_row_state(keypad);

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

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

        for (row = 0; row < keypad->num_row_gpios; row++)
                gpiod_direction_input(keypad->row_gpios[row]);

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

                activate_col(keypad, col, true);

                new_state[col] = read_row_state(keypad);

                activate_col(keypad, col, false);
        }

        for (col = 0; col < keypad->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 < keypad->num_row_gpios; row++) {
                        if (!(bits_changed & BIT(row)))
                                continue;

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

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

        activate_all_cols(keypad, true);

        /* Enable IRQs again */
        scoped_guard(spinlock_irq, &keypad->lock) {
                keypad->scan_pending = false;
                enable_row_irqs(keypad);
        }

        /* read new row state and detect if value has changed */
        new_row_state = read_row_state(keypad);
        if (init_row_state != new_row_state) {
                guard(spinlock_irq)(&keypad->lock);
                if (unlikely(keypad->scan_pending || keypad->stopped))
                        return;
                disable_row_irqs(keypad);
                keypad->scan_pending = true;
                schedule_delayed_work(&keypad->work,
                                      msecs_to_jiffies(keypad->debounce_ms));
        }
}

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

        guard(spinlock_irqsave)(&keypad->lock);

        /*
         * 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->debounce_ms));

out:
        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);

        scoped_guard(spinlock_irq, &keypad->lock) {
                keypad->stopped = true;
        }

        flush_delayed_work(&keypad->work);
        /*
         * matrix_keypad_scan() will leave IRQs enabled;
         * we should disable them now.
         */
        disable_row_irqs(keypad);
}

static void matrix_keypad_enable_wakeup(struct matrix_keypad *keypad)
{
        int i;

        for_each_clear_bit(i, keypad->wakeup_enabled_irqs,
                           keypad->num_row_gpios)
                if (enable_irq_wake(keypad->row_irqs[i]) == 0)
                        __set_bit(i, keypad->wakeup_enabled_irqs);
}

static void matrix_keypad_disable_wakeup(struct matrix_keypad *keypad)
{
        int i;

        for_each_set_bit(i, keypad->wakeup_enabled_irqs,
                         keypad->num_row_gpios) {
                disable_irq_wake(keypad->row_irqs[i]);
                __clear_bit(i, keypad->wakeup_enabled_irqs);
        }
}

static int matrix_keypad_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct matrix_keypad *keypad = platform_get_drvdata(pdev);

        matrix_keypad_stop(keypad->input_dev);

        if (device_may_wakeup(&pdev->dev))
                matrix_keypad_enable_wakeup(keypad);

        return 0;
}

static int matrix_keypad_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct matrix_keypad *keypad = platform_get_drvdata(pdev);

        if (device_may_wakeup(&pdev->dev))
                matrix_keypad_disable_wakeup(keypad);

        matrix_keypad_start(keypad->input_dev);

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(matrix_keypad_pm_ops,
                                matrix_keypad_suspend, matrix_keypad_resume);

static int matrix_keypad_init_gpio(struct platform_device *pdev,
                                   struct matrix_keypad *keypad)
{
        bool active_low;
        int nrow, ncol;
        int err;
        int i;

        nrow = gpiod_count(&pdev->dev, "row");
        ncol = gpiod_count(&pdev->dev, "col");
        if (nrow < 0 || ncol < 0) {
                dev_err(&pdev->dev, "missing row or column GPIOs\n");
                return -EINVAL;
        }

        keypad->num_row_gpios = nrow;
        keypad->num_col_gpios = ncol;

        active_low = device_property_read_bool(&pdev->dev, "gpio-activelow");

        /* initialize strobe lines as outputs, activated */
        for (i = 0; i < keypad->num_col_gpios; i++) {
                keypad->col_gpios[i] = devm_gpiod_get_index(&pdev->dev, "col",
                                                            i, GPIOD_ASIS);
                err = PTR_ERR_OR_ZERO(keypad->col_gpios[i]);
                if (err) {
                        dev_err(&pdev->dev,
                                "failed to request GPIO for COL%d: %d\n",
                                i, err);
                        return err;
                }

                gpiod_set_consumer_name(keypad->col_gpios[i], "matrix_kbd_col");

                if (active_low ^ gpiod_is_active_low(keypad->col_gpios[i]))
                        gpiod_toggle_active_low(keypad->col_gpios[i]);

                gpiod_direction_output(keypad->col_gpios[i], 1);
        }

        for (i = 0; i < keypad->num_row_gpios; i++) {
                keypad->row_gpios[i] = devm_gpiod_get_index(&pdev->dev, "row",
                                                            i, GPIOD_IN);
                err = PTR_ERR_OR_ZERO(keypad->row_gpios[i]);
                if (err) {
                        dev_err(&pdev->dev,
                                "failed to request GPIO for ROW%d: %d\n",
                                i, err);
                        return err;
                }

                gpiod_set_consumer_name(keypad->row_gpios[i], "matrix_kbd_row");

                if (active_low ^ gpiod_is_active_low(keypad->row_gpios[i]))
                        gpiod_toggle_active_low(keypad->row_gpios[i]);
        }

        return 0;
}

static int matrix_keypad_setup_interrupts(struct platform_device *pdev,
                                          struct matrix_keypad *keypad)
{
        int err;
        int irq;
        int i;

        for (i = 0; i < keypad->num_row_gpios; i++) {
                irq = gpiod_to_irq(keypad->row_gpios[i]);
                if (irq < 0) {
                        err = irq;
                        dev_err(&pdev->dev,
                                "Unable to convert GPIO line %i to irq: %d\n",
                                i, err);
                        return err;
                }

                err = devm_request_any_context_irq(&pdev->dev, irq,
                                                   matrix_keypad_interrupt,
                                                   IRQF_TRIGGER_RISING |
                                                        IRQF_TRIGGER_FALLING,
                                                   "matrix-keypad", keypad);
                if (err < 0) {
                        dev_err(&pdev->dev,
                                "Unable to acquire interrupt for row %i: %d\n",
                                i, err);
                        return err;
                }

                keypad->row_irqs[i] = irq;
        }

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

        return 0;
}

static int matrix_keypad_probe(struct platform_device *pdev)
{
        struct matrix_keypad *keypad;
        struct input_dev *input_dev;
        bool wakeup;
        int err;

        keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
        if (!keypad)
                return -ENOMEM;

        input_dev = devm_input_allocate_device(&pdev->dev);
        if (!input_dev)
                return -ENOMEM;

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

        keypad->drive_inactive_cols =
                device_property_read_bool(&pdev->dev, "drive-inactive-cols");
        device_property_read_u32(&pdev->dev, "debounce-delay-ms",
                                 &keypad->debounce_ms);
        device_property_read_u32(&pdev->dev, "col-scan-delay-us",
                                 &keypad->col_scan_delay_us);
        device_property_read_u32(&pdev->dev, "all-cols-on-delay-us",
                                 &keypad->all_cols_on_delay_us);

        err = matrix_keypad_init_gpio(pdev, keypad);
        if (err)
                return err;

        keypad->row_shift = get_count_order(keypad->num_col_gpios);

        err = matrix_keypad_setup_interrupts(pdev, keypad);
        if (err)
                return err;

        input_dev->name         = pdev->name;
        input_dev->id.bustype   = BUS_HOST;
        input_dev->open         = matrix_keypad_start;
        input_dev->close        = matrix_keypad_stop;

        err = matrix_keypad_build_keymap(NULL, NULL,
                                         keypad->num_row_gpios,
                                         keypad->num_col_gpios,
                                         NULL, input_dev);
        if (err) {
                dev_err(&pdev->dev, "failed to build keymap\n");
                return -ENOMEM;
        }

        if (!device_property_read_bool(&pdev->dev, "linux,no-autorepeat"))
                __set_bit(EV_REP, input_dev->evbit);

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

        err = input_register_device(keypad->input_dev);
        if (err)
                return err;

        wakeup = device_property_read_bool(&pdev->dev, "wakeup-source") ||
                 /* legacy */
                 device_property_read_bool(&pdev->dev, "linux,wakeup");
        device_init_wakeup(&pdev->dev, wakeup);

        platform_set_drvdata(pdev, keypad);

        return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id matrix_keypad_dt_match[] = {
        { .compatible = "gpio-matrix-keypad" },
        { }
};
MODULE_DEVICE_TABLE(of, matrix_keypad_dt_match);
#endif

static struct platform_driver matrix_keypad_driver = {
        .probe          = matrix_keypad_probe,
        .driver         = {
                .name   = "matrix-keypad",
                .pm     = pm_sleep_ptr(&matrix_keypad_pm_ops),
                .of_match_table = of_match_ptr(matrix_keypad_dt_match),
        },
};
module_platform_driver(matrix_keypad_driver);

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