mpr121_touchkey.c

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/*
 * Touchkey driver for Freescale MPR121 Controllor
 *
 * Copyright (C) 2011 Freescale Semiconductor, Inc.
 * Author: Zhang Jiejing <[email protected]>
 *
 * Based on mcs_touchkey.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/module.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/i2c/mpr121_touchkey.h>

/* Register definitions */
#define ELE_TOUCH_STATUS_0_ADDR 0x0
#define ELE_TOUCH_STATUS_1_ADDR 0X1
#define MHD_RISING_ADDR     0x2b
#define NHD_RISING_ADDR     0x2c
#define NCL_RISING_ADDR     0x2d
#define FDL_RISING_ADDR     0x2e
#define MHD_FALLING_ADDR    0x2f
#define NHD_FALLING_ADDR    0x30
#define NCL_FALLING_ADDR    0x31
#define FDL_FALLING_ADDR    0x32
#define ELE0_TOUCH_THRESHOLD_ADDR   0x41
#define ELE0_RELEASE_THRESHOLD_ADDR 0x42
#define AFE_CONF_ADDR           0x5c
#define FILTER_CONF_ADDR        0x5d

/*
 * ELECTRODE_CONF_ADDR: This register configures the number of
 * enabled capacitance sensing inputs and its run/suspend mode.
 */
#define ELECTRODE_CONF_ADDR     0x5e
#define ELECTRODE_CONF_QUICK_CHARGE 0x80
#define AUTO_CONFIG_CTRL_ADDR       0x7b
#define AUTO_CONFIG_USL_ADDR        0x7d
#define AUTO_CONFIG_LSL_ADDR        0x7e
#define AUTO_CONFIG_TL_ADDR     0x7f

/* Threshold of touch/release trigger */
#define TOUCH_THRESHOLD         0x08
#define RELEASE_THRESHOLD       0x05
/* Masks for touch and release triggers */
#define TOUCH_STATUS_MASK       0xfff
/* MPR121 has 12 keys */
#define MPR121_MAX_KEY_COUNT        12

struct mpr121_touchkey {
    struct i2c_client   *client;
    struct input_dev    *input_dev;
    unsigned int        key_val;
    unsigned int        statusbits;
    unsigned int        keycount;
    u16         keycodes[MPR121_MAX_KEY_COUNT];
};

struct mpr121_init_register {
    int addr;
    u8 val;
};

static const struct mpr121_init_register init_reg_table[] __devinitconst = {
    { MHD_RISING_ADDR,  0x1 },
    { NHD_RISING_ADDR,  0x1 },
    { MHD_FALLING_ADDR, 0x1 },
    { NHD_FALLING_ADDR, 0x1 },
    { NCL_FALLING_ADDR, 0xff },
    { FDL_FALLING_ADDR, 0x02 },
    { FILTER_CONF_ADDR, 0x04 },
    { AFE_CONF_ADDR,    0x0b },
    { AUTO_CONFIG_CTRL_ADDR, 0x0b },
};

static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
{
    struct mpr121_touchkey *mpr121 = dev_id;
    struct i2c_client *client = mpr121->client;
    struct input_dev *input = mpr121->input_dev;
    unsigned int key_num, key_val, pressed;
    int reg;

    reg = i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_1_ADDR);
    if (reg < 0) {
        dev_err(&client->dev, "i2c read error [%d]\n", reg);
        goto out;
    }

    reg <<= 8;
    reg |= i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_0_ADDR);
    if (reg < 0) {
        dev_err(&client->dev, "i2c read error [%d]\n", reg);
        goto out;
    }

    reg &= TOUCH_STATUS_MASK;
    /* use old press bit to figure out which bit changed */
    key_num = ffs(reg ^ mpr121->statusbits) - 1;
    pressed = reg & (1 << key_num);
    mpr121->statusbits = reg;

    key_val = mpr121->keycodes[key_num];

    input_event(input, EV_MSC, MSC_SCAN, key_num);
    input_report_key(input, key_val, pressed);
    input_sync(input);

    dev_dbg(&client->dev, "key %d %d %s\n", key_num, key_val,
        pressed ? "pressed" : "released");

out:
    return IRQ_HANDLED;
}

static int __devinit mpr121_phys_init(const struct mpr121_platform_data *pdata,
                      struct mpr121_touchkey *mpr121,
                      struct i2c_client *client)
{
    const struct mpr121_init_register *reg;
    unsigned char usl, lsl, tl, eleconf;
    int i, t, vdd, ret;

    /* Set up touch/release threshold for ele0-ele11 */
    for (i = 0; i <= MPR121_MAX_KEY_COUNT; i++) {
        t = ELE0_TOUCH_THRESHOLD_ADDR + (i * 2);
        ret = i2c_smbus_write_byte_data(client, t, TOUCH_THRESHOLD);
        if (ret < 0)
            goto err_i2c_write;
        ret = i2c_smbus_write_byte_data(client, t + 1,
                        RELEASE_THRESHOLD);
        if (ret < 0)
            goto err_i2c_write;
    }

    /* Set up init register */
    for (i = 0; i < ARRAY_SIZE(init_reg_table); i++) {
        reg = &init_reg_table[i];
        ret = i2c_smbus_write_byte_data(client, reg->addr, reg->val);
        if (ret < 0)
            goto err_i2c_write;
    }


    /*
     * Capacitance on sensing input varies and needs to be compensated.
     * The internal MPR121-auto-configuration can do this if it's
     * registers are set properly (based on pdata->vdd_uv).
     */
    vdd = pdata->vdd_uv / 1000;
    usl = ((vdd - 700) * 256) / vdd;
    lsl = (usl * 65) / 100;
    tl = (usl * 90) / 100;
    ret = i2c_smbus_write_byte_data(client, AUTO_CONFIG_USL_ADDR, usl);
    ret |= i2c_smbus_write_byte_data(client, AUTO_CONFIG_LSL_ADDR, lsl);
    ret |= i2c_smbus_write_byte_data(client, AUTO_CONFIG_TL_ADDR, tl);

    /*
     * Quick charge bit will let the capacitive charge to ready
     * state quickly, or the buttons may not function after system
     * boot.
     */
    eleconf = mpr121->keycount | ELECTRODE_CONF_QUICK_CHARGE;
    ret |= i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR,
                     eleconf);
    if (ret != 0)
        goto err_i2c_write;

    dev_dbg(&client->dev, "set up with %x keys.\n", mpr121->keycount);

    return 0;

err_i2c_write:
    dev_err(&client->dev, "i2c write error: %d\n", ret);
    return ret;
}

static int __devinit mpr_touchkey_probe(struct i2c_client *client,
                    const struct i2c_device_id *id)
{
    const struct mpr121_platform_data *pdata = client->dev.platform_data;
    struct mpr121_touchkey *mpr121;
    struct input_dev *input_dev;
    int error;
    int i;

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

    if (!pdata->keymap || !pdata->keymap_size) {
        dev_err(&client->dev, "missing keymap data\n");
        return -EINVAL;
    }

    if (pdata->keymap_size > MPR121_MAX_KEY_COUNT) {
        dev_err(&client->dev, "too many keys defined\n");
        return -EINVAL;
    }

    if (!client->irq) {
        dev_err(&client->dev, "irq number should not be zero\n");
        return -EINVAL;
    }

    mpr121 = kzalloc(sizeof(struct mpr121_touchkey), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!mpr121 || !input_dev) {
        dev_err(&client->dev, "Failed to allocate memory\n");
        error = -ENOMEM;
        goto err_free_mem;
    }

    mpr121->client = client;
    mpr121->input_dev = input_dev;
    mpr121->keycount = pdata->keymap_size;

    input_dev->name = "Freescale MPR121 Touchkey";
    input_dev->id.bustype = BUS_I2C;
    input_dev->dev.parent = &client->dev;
    input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);

    input_dev->keycode = mpr121->keycodes;
    input_dev->keycodesize = sizeof(mpr121->keycodes[0]);
    input_dev->keycodemax = mpr121->keycount;

    for (i = 0; i < pdata->keymap_size; i++) {
        input_set_capability(input_dev, EV_KEY, pdata->keymap[i]);
        mpr121->keycodes[i] = pdata->keymap[i];
    }

    error = mpr121_phys_init(pdata, mpr121, client);
    if (error) {
        dev_err(&client->dev, "Failed to init register\n");
        goto err_free_mem;
    }

    error = request_threaded_irq(client->irq, NULL,
                     mpr_touchkey_interrupt,
                     IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                     client->dev.driver->name, mpr121);
    if (error) {
        dev_err(&client->dev, "Failed to register interrupt\n");
        goto err_free_mem;
    }

    error = input_register_device(input_dev);
    if (error)
        goto err_free_irq;

    i2c_set_clientdata(client, mpr121);
    device_init_wakeup(&client->dev, pdata->wakeup);

    return 0;

err_free_irq:
    free_irq(client->irq, mpr121);
err_free_mem:
    input_free_device(input_dev);
    kfree(mpr121);
    return error;
}

static int __devexit mpr_touchkey_remove(struct i2c_client *client)
{
    struct mpr121_touchkey *mpr121 = i2c_get_clientdata(client);

    free_irq(client->irq, mpr121);
    input_unregister_device(mpr121->input_dev);
    kfree(mpr121);

    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int mpr_suspend(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);

    if (device_may_wakeup(&client->dev))
        enable_irq_wake(client->irq);

    i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR, 0x00);

    return 0;
}

static int mpr_resume(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct mpr121_touchkey *mpr121 = i2c_get_clientdata(client);

    if (device_may_wakeup(&client->dev))
        disable_irq_wake(client->irq);

    i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR,
                  mpr121->keycount);

    return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(mpr121_touchkey_pm_ops, mpr_suspend, mpr_resume);

static const struct i2c_device_id mpr121_id[] = {
    { "mpr121_touchkey", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, mpr121_id);

static struct i2c_driver mpr_touchkey_driver = {
    .driver = {
        .name   = "mpr121",
        .owner  = THIS_MODULE,
        .pm = &mpr121_touchkey_pm_ops,
    },
    .id_table   = mpr121_id,
    .probe      = mpr_touchkey_probe,
    .remove     = __devexit_p(mpr_touchkey_remove),
};

module_i2c_driver(mpr_touchkey_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Zhang Jiejing <[email protected]>");
MODULE_DESCRIPTION("Touch Key driver for Freescale MPR121 Chip");