/*
 * Driver for the IMX keypad port.
 * Copyright (C) 2009 Alberto Panizzo <maramaopercheseimorto@gmail.com>
 *
 * 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/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/input/matrix_keypad.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/timer.h>

/*
 * Keypad Controller registers (halfword)
 */
#define KPCR            0x00 /* Keypad Control Register */

#define KPSR            0x02 /* Keypad Status Register */
#define KBD_STAT_KPKD   (0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
#define KBD_STAT_KPKR   (0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
#define KBD_STAT_KDSC   (0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
#define KBD_STAT_KRSS   (0x1 << 3) /* Key Release Synch Status bit (w1c)*/
#define KBD_STAT_KDIE   (0x1 << 8) /* Key Depress Interrupt Enable Status bit */
#define KBD_STAT_KRIE   (0x1 << 9) /* Key Release Interrupt Enable */
#define KBD_STAT_KPPEN  (0x1 << 10) /* Keypad Clock Enable */

#define KDDR            0x04 /* Keypad Data Direction Register */
#define KPDR            0x06 /* Keypad Data Register */

#define MAX_MATRIX_KEY_ROWS     8
#define MAX_MATRIX_KEY_COLS     8
#define MATRIX_ROW_SHIFT        3

#define MAX_MATRIX_KEY_NUM      (MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)

struct imx_keypad {

        struct clk *clk;
        struct input_dev *input_dev;
        void __iomem *mmio_base;

        int                     irq;
        struct timer_list       check_matrix_timer;

        /*
         * The matrix is stable only if no changes are detected after
         * IMX_KEYPAD_SCANS_FOR_STABILITY scans
         */
#define IMX_KEYPAD_SCANS_FOR_STABILITY 3
        int                     stable_count;

        bool                    enabled;

        /* Masks for enabled rows/cols */
        unsigned short          rows_en_mask;
        unsigned short          cols_en_mask;

        unsigned short          keycodes[MAX_MATRIX_KEY_NUM];

        /*
         * Matrix states:
         * -stable: achieved after a complete debounce process.
         * -unstable: used in the debouncing process.
         */
        unsigned short          matrix_stable_state[MAX_MATRIX_KEY_COLS];
        unsigned short          matrix_unstable_state[MAX_MATRIX_KEY_COLS];
};

/* Scan the matrix and return the new state in *matrix_volatile_state. */
static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
                                  unsigned short *matrix_volatile_state)
{
        int col;
        unsigned short reg_val;

        for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
                if ((keypad->cols_en_mask & (1 << col)) == 0)
                        continue;
                /*
                 * Discharge keypad capacitance:
                 * 2. write 1s on column data.
                 * 3. configure columns as totem-pole to discharge capacitance.
                 * 4. configure columns as open-drain.
                 */
                reg_val = readw(keypad->mmio_base + KPDR);
                reg_val |= 0xff00;
                writew(reg_val, keypad->mmio_base + KPDR);

                reg_val = readw(keypad->mmio_base + KPCR);
                reg_val &= ~((keypad->cols_en_mask & 0xff) << 8);
                writew(reg_val, keypad->mmio_base + KPCR);

                udelay(2);

                reg_val = readw(keypad->mmio_base + KPCR);
                reg_val |= (keypad->cols_en_mask & 0xff) << 8;
                writew(reg_val, keypad->mmio_base + KPCR);

                /*
                 * 5. Write a single column to 0, others to 1.
                 * 6. Sample row inputs and save data.
                 * 7. Repeat steps 2 - 6 for remaining columns.
                 */
                reg_val = readw(keypad->mmio_base + KPDR);
                reg_val &= ~(1 << (8 + col));
                writew(reg_val, keypad->mmio_base + KPDR);

                /*
                 * Delay added to avoid propagating the 0 from column to row
                 * when scanning.
                 */
                udelay(5);

                /*
                 * 1s in matrix_volatile_state[col] means key pressures
                 * throw data from non enabled rows.
                 */
                reg_val = readw(keypad->mmio_base + KPDR);
                matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
        }

        /*
         * Return in standby mode:
         * 9. write 0s to columns
         */
        reg_val = readw(keypad->mmio_base + KPDR);
        reg_val &= 0x00ff;
        writew(reg_val, keypad->mmio_base + KPDR);
}

/*
 * Compare the new matrix state (volatile) with the stable one stored in
 * keypad->matrix_stable_state and fire events if changes are detected.
 */
static void imx_keypad_fire_events(struct imx_keypad *keypad,
                                   unsigned short *matrix_volatile_state)
{
        struct input_dev *input_dev = keypad->input_dev;
        int row, col;

        for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
                unsigned short bits_changed;
                int code;

                if ((keypad->cols_en_mask & (1 << col)) == 0)
                        continue; /* Column is not enabled */

                bits_changed = keypad->matrix_stable_state[col] ^
                                                matrix_volatile_state[col];

                if (bits_changed == 0)
                        continue; /* Column does not contain changes */

                for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
                        if ((keypad->rows_en_mask & (1 << row)) == 0)
                                continue; /* Row is not enabled */
                        if ((bits_changed & (1 << row)) == 0)
                                continue; /* Row does not contain changes */

                        code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
                        input_event(input_dev, EV_MSC, MSC_SCAN, code);
                        input_report_key(input_dev, keypad->keycodes[code],
                                matrix_volatile_state[col] & (1 << row));
                        dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
                                keypad->keycodes[code],
                                matrix_volatile_state[col] & (1 << row));
                }
        }
        input_sync(input_dev);
}

/*
 * imx_keypad_check_for_events is the timer handler.
 */
static void imx_keypad_check_for_events(unsigned long data)
{
        struct imx_keypad *keypad = (struct imx_keypad *) data;
        unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
        unsigned short reg_val;
        bool state_changed, is_zero_matrix;
        int i;

        memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));

        imx_keypad_scan_matrix(keypad, matrix_volatile_state);

        state_changed = false;
        for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
                if ((keypad->cols_en_mask & (1 << i)) == 0)
                        continue;

                if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
                        state_changed = true;
                        break;
                }
        }

        /*
         * If the matrix state is changed from the previous scan
         *   (Re)Begin the debouncing process, saving the new state in
         *    keypad->matrix_unstable_state.
         * else
         *   Increase the count of number of scans with a stable state.
         */
        if (state_changed) {
                memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
                        sizeof(matrix_volatile_state));
                keypad->stable_count = 0;
        } else
                keypad->stable_count++;

        /*
         * If the matrix is not as stable as we want reschedule scan
         * in the near future.
         */
        if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
                mod_timer(&keypad->check_matrix_timer,
                          jiffies + msecs_to_jiffies(10));
                return;
        }

        /*
         * If the matrix state is stable, fire the events and save the new
         * stable state. Note, if the matrix is kept stable for longer
         * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
         * events have already been generated.
         */
        if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
                imx_keypad_fire_events(keypad, matrix_volatile_state);

                memcpy(keypad->matrix_stable_state, matrix_volatile_state,
                        sizeof(matrix_volatile_state));
        }

        is_zero_matrix = true;
        for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
                if (matrix_volatile_state[i] != 0) {
                        is_zero_matrix = false;
                        break;
                }
        }


        if (is_zero_matrix) {
                /*
                 * All keys have been released. Enable only the KDI
                 * interrupt for future key presses (clear the KDI
                 * status bit and its sync chain before that).
                 */
                reg_val = readw(keypad->mmio_base + KPSR);
                reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
                writew(reg_val, keypad->mmio_base + KPSR);

                reg_val = readw(keypad->mmio_base + KPSR);
                reg_val |= KBD_STAT_KDIE;
                reg_val &= ~KBD_STAT_KRIE;
                writew(reg_val, keypad->mmio_base + KPSR);
        } else {
                /*
                 * Some keys are still pressed. Schedule a rescan in
                 * attempt to detect multiple key presses and enable
                 * the KRI interrupt to react quickly to key release
                 * event.
                 */
                mod_timer(&keypad->check_matrix_timer,
                          jiffies + msecs_to_jiffies(60));

                reg_val = readw(keypad->mmio_base + KPSR);
                reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
                writew(reg_val, keypad->mmio_base + KPSR);

                reg_val = readw(keypad->mmio_base + KPSR);
                reg_val |= KBD_STAT_KRIE;
                reg_val &= ~KBD_STAT_KDIE;
                writew(reg_val, keypad->mmio_base + KPSR);
        }
}

static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
{
        struct imx_keypad *keypad = dev_id;
        unsigned short reg_val;

        reg_val = readw(keypad->mmio_base + KPSR);

        /* Disable both interrupt types */
        reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
        /* Clear interrupts status bits */
        reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
        writew(reg_val, keypad->mmio_base + KPSR);

        if (keypad->enabled) {
                /* The matrix is supposed to be changed */
                keypad->stable_count = 0;

                /* Schedule the scanning procedure near in the future */
                mod_timer(&keypad->check_matrix_timer,
                          jiffies + msecs_to_jiffies(2));
        }

        return IRQ_HANDLED;
}

static void imx_keypad_config(struct imx_keypad *keypad)
{
        unsigned short reg_val;

        /*
         * Include enabled rows in interrupt generation (KPCR[7:0])
         * Configure keypad columns as open-drain (KPCR[15:8])
         */
        reg_val = readw(keypad->mmio_base + KPCR);
        reg_val |= keypad->rows_en_mask & 0xff;         /* rows */
        reg_val |= (keypad->cols_en_mask & 0xff) << 8;  /* cols */
        writew(reg_val, keypad->mmio_base + KPCR);

        /* Write 0's to KPDR[15:8] (Colums) */
        reg_val = readw(keypad->mmio_base + KPDR);
        reg_val &= 0x00ff;
        writew(reg_val, keypad->mmio_base + KPDR);

        /* Configure columns as output, rows as input (KDDR[15:0]) */
        writew(0xff00, keypad->mmio_base + KDDR);

        /*
         * Clear Key Depress and Key Release status bit.
         * Clear both synchronizer chain.
         */
        reg_val = readw(keypad->mmio_base + KPSR);
        reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
                   KBD_STAT_KDSC | KBD_STAT_KRSS;
        writew(reg_val, keypad->mmio_base + KPSR);

        /* Enable KDI and disable KRI (avoid false release events). */
        reg_val |= KBD_STAT_KDIE;
        reg_val &= ~KBD_STAT_KRIE;
        writew(reg_val, keypad->mmio_base + KPSR);
}

static void imx_keypad_inhibit(struct imx_keypad *keypad)
{
        unsigned short reg_val;

        /* Inhibit KDI and KRI interrupts. */
        reg_val = readw(keypad->mmio_base + KPSR);
        reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
        reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
        writew(reg_val, keypad->mmio_base + KPSR);

        /* Colums as open drain and disable all rows */
        reg_val = (keypad->cols_en_mask & 0xff) << 8;
        writew(reg_val, keypad->mmio_base + KPCR);
}

static void imx_keypad_close(struct input_dev *dev)
{
        struct imx_keypad *keypad = input_get_drvdata(dev);

        dev_dbg(&dev->dev, ">%s\n", __func__);

        /* Mark keypad as being inactive */
        keypad->enabled = false;
        synchronize_irq(keypad->irq);
        del_timer_sync(&keypad->check_matrix_timer);

        imx_keypad_inhibit(keypad);

        /* Disable clock unit */
        clk_disable_unprepare(keypad->clk);
}

static int imx_keypad_open(struct input_dev *dev)
{
        struct imx_keypad *keypad = input_get_drvdata(dev);
        int error;

        dev_dbg(&dev->dev, ">%s\n", __func__);

        /* Enable the kpp clock */
        error = clk_prepare_enable(keypad->clk);
        if (error)
                return error;

        /* We became active from now */
        keypad->enabled = true;

        imx_keypad_config(keypad);

        /* Sanity control, not all the rows must be actived now. */
        if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
                dev_err(&dev->dev,
                        "too many keys pressed, control pins initialisation\n");
                goto open_err;
        }

        return 0;

open_err:
        imx_keypad_close(dev);
        return -EIO;
}

#ifdef CONFIG_OF
static const struct of_device_id imx_keypad_of_match[] = {
        { .compatible = "fsl,imx21-kpp", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
#endif

static int imx_keypad_probe(struct platform_device *pdev)
{
        const struct matrix_keymap_data *keymap_data =
                        dev_get_platdata(&pdev->dev);
        struct imx_keypad *keypad;
        struct input_dev *input_dev;
        struct resource *res;
        int irq, error, i, row, col;

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

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "no irq defined in platform data\n");
                return irq;
        }

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

        keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
        if (!keypad) {
                dev_err(&pdev->dev, "not enough memory for driver data\n");
                return -ENOMEM;
        }

        keypad->input_dev = input_dev;
        keypad->irq = irq;
        keypad->stable_count = 0;

        setup_timer(&keypad->check_matrix_timer,
                    imx_keypad_check_for_events, (unsigned long) keypad);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        keypad->mmio_base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(keypad->mmio_base))
                return PTR_ERR(keypad->mmio_base);

        keypad->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(keypad->clk)) {
                dev_err(&pdev->dev, "failed to get keypad clock\n");
                return PTR_ERR(keypad->clk);
        }

        /* Init the Input device */
        input_dev->name = pdev->name;
        input_dev->id.bustype = BUS_HOST;
        input_dev->dev.parent = &pdev->dev;
        input_dev->open = imx_keypad_open;
        input_dev->close = imx_keypad_close;

        error = matrix_keypad_build_keymap(keymap_data, NULL,
                                           MAX_MATRIX_KEY_ROWS,
                                           MAX_MATRIX_KEY_COLS,
                                           keypad->keycodes, input_dev);
        if (error) {
                dev_err(&pdev->dev, "failed to build keymap\n");
                return error;
        }

        /* Search for rows and cols enabled */
        for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
                for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
                        i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
                        if (keypad->keycodes[i] != KEY_RESERVED) {
                                keypad->rows_en_mask |= 1 << row;
                                keypad->cols_en_mask |= 1 << col;
                        }
                }
        }
        dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
        dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);

        __set_bit(EV_REP, input_dev->evbit);
        input_set_capability(input_dev, EV_MSC, MSC_SCAN);
        input_set_drvdata(input_dev, keypad);

        /* Ensure that the keypad will stay dormant until opened */
        error = clk_prepare_enable(keypad->clk);
        if (error)
                return error;
        imx_keypad_inhibit(keypad);
        clk_disable_unprepare(keypad->clk);

        error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
                            pdev->name, keypad);
        if (error) {
                dev_err(&pdev->dev, "failed to request IRQ\n");
                return error;
        }

        /* Register the input device */
        error = input_register_device(input_dev);
        if (error) {
                dev_err(&pdev->dev, "failed to register input device\n");
                return error;
        }

        platform_set_drvdata(pdev, keypad);
        device_init_wakeup(&pdev->dev, 1);

        return 0;
}

static int __maybe_unused imx_kbd_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct imx_keypad *kbd = platform_get_drvdata(pdev);
        struct input_dev *input_dev = kbd->input_dev;

        /* imx kbd can wake up system even clock is disabled */
        mutex_lock(&input_dev->mutex);

        if (input_dev->users)
                clk_disable_unprepare(kbd->clk);

        mutex_unlock(&input_dev->mutex);

        if (device_may_wakeup(&pdev->dev))
                enable_irq_wake(kbd->irq);

        return 0;
}

static int __maybe_unused imx_kbd_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct imx_keypad *kbd = platform_get_drvdata(pdev);
        struct input_dev *input_dev = kbd->input_dev;
        int ret = 0;

        if (device_may_wakeup(&pdev->dev))
                disable_irq_wake(kbd->irq);

        mutex_lock(&input_dev->mutex);

        if (input_dev->users) {
                ret = clk_prepare_enable(kbd->clk);
                if (ret)
                        goto err_clk;
        }

err_clk:
        mutex_unlock(&input_dev->mutex);

        return ret;
}

static SIMPLE_DEV_PM_OPS(imx_kbd_pm_ops, imx_kbd_suspend, imx_kbd_resume);

static struct platform_driver imx_keypad_driver = {
        .driver         = {
                .name   = "imx-keypad",
                .pm     = &imx_kbd_pm_ops,
                .of_match_table = of_match_ptr(imx_keypad_of_match),
        },
        .probe          = imx_keypad_probe,
};
module_platform_driver(imx_keypad_driver);

MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
MODULE_DESCRIPTION("IMX Keypad Port Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:imx-keypad");