imx_keypad.c

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/*
 * Driver for the IMX keypad port.
 * Copyright (C) 2009 Alberto Panizzo <[email protected]>
 *
 * 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.
 *
 * <<Power management needs to be implemented>>.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.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/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 */
    writew(0xff00, 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;
}

static int __devinit imx_keypad_probe(struct platform_device *pdev)
{
    const struct matrix_keymap_data *keymap_data = pdev->dev.platform_data;
    struct imx_keypad *keypad;
    struct input_dev *input_dev;
    struct resource *res;
    int irq, error, i;

    if (keymap_data == NULL) {
        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 -EINVAL;
    }

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (res == NULL) {
        dev_err(&pdev->dev, "no I/O memory defined in platform data\n");
        return -EINVAL;
    }

    res = request_mem_region(res->start, resource_size(res), pdev->name);
    if (res == NULL) {
        dev_err(&pdev->dev, "failed to request I/O memory\n");
        return -EBUSY;
    }

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

    keypad = kzalloc(sizeof(struct imx_keypad), GFP_KERNEL);
    if (!keypad) {
        dev_err(&pdev->dev, "not enough memory for driver data\n");
        error = -ENOMEM;
        goto failed_free_input;
    }

    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);

    keypad->mmio_base = ioremap(res->start, resource_size(res));
    if (keypad->mmio_base == NULL) {
        dev_err(&pdev->dev, "failed to remap I/O memory\n");
        error = -ENOMEM;
        goto failed_free_priv;
    }

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

    /* Search for rows and cols enabled */
    for (i = 0; i < keymap_data->keymap_size; i++) {
        keypad->rows_en_mask |= 1 << KEY_ROW(keymap_data->keymap[i]);
        keypad->cols_en_mask |= 1 << KEY_COL(keymap_data->keymap[i]);
    }

    if (keypad->rows_en_mask > ((1 << MAX_MATRIX_KEY_ROWS) - 1) ||
        keypad->cols_en_mask > ((1 << MAX_MATRIX_KEY_COLS) - 1)) {
        dev_err(&pdev->dev,
            "invalid key data (too many rows or colums)\n");
        error = -EINVAL;
        goto failed_clock_put;
    }
    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);

    /* 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");
        goto failed_clock_put;
    }

    __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 */
    clk_prepare_enable(keypad->clk);
    imx_keypad_inhibit(keypad);
    clk_disable_unprepare(keypad->clk);

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

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

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

    return 0;

failed_free_irq:
    free_irq(irq, pdev);
failed_clock_put:
    clk_put(keypad->clk);
failed_unmap:
    iounmap(keypad->mmio_base);
failed_free_priv:
    kfree(keypad);
failed_free_input:
    input_free_device(input_dev);
failed_rel_mem:
    release_mem_region(res->start, resource_size(res));
    return error;
}

static int __devexit imx_keypad_remove(struct platform_device *pdev)
{
    struct imx_keypad *keypad = platform_get_drvdata(pdev);
    struct resource *res;

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

    platform_set_drvdata(pdev, NULL);

    input_unregister_device(keypad->input_dev);

    free_irq(keypad->irq, keypad);
    clk_put(keypad->clk);

    iounmap(keypad->mmio_base);
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    release_mem_region(res->start, resource_size(res));

    kfree(keypad);

    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int 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 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;
}
#endif

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",
        .owner  = THIS_MODULE,
        .pm = &imx_kbd_pm_ops,
    },
    .probe      = imx_keypad_probe,
    .remove     = __devexit_p(imx_keypad_remove),
};
module_platform_driver(imx_keypad_driver);

MODULE_AUTHOR("Alberto Panizzo <[email protected]>");
MODULE_DESCRIPTION("IMX Keypad Port Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:imx-keypad");