qt2160.c

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/*
 *  qt2160.c - Atmel AT42QT2160 Touch Sense Controller
 *
 *  Copyright (C) 2009 Raphael Derosso Pereira <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/input.h>

#define QT2160_VALID_CHIPID  0x11

#define QT2160_CMD_CHIPID     0
#define QT2160_CMD_CODEVER    1
#define QT2160_CMD_GSTAT      2
#define QT2160_CMD_KEYS3      3
#define QT2160_CMD_KEYS4      4
#define QT2160_CMD_SLIDE      5
#define QT2160_CMD_GPIOS      6
#define QT2160_CMD_SUBVER     7
#define QT2160_CMD_CALIBRATE  10

#define QT2160_CYCLE_INTERVAL   (2*HZ)

static unsigned char qt2160_key2code[] = {
    KEY_0, KEY_1, KEY_2, KEY_3,
    KEY_4, KEY_5, KEY_6, KEY_7,
    KEY_8, KEY_9, KEY_A, KEY_B,
    KEY_C, KEY_D, KEY_E, KEY_F,
};

struct qt2160_data {
    struct i2c_client *client;
    struct input_dev *input;
    struct delayed_work dwork;
    spinlock_t lock;        /* Protects canceling/rescheduling of dwork */
    unsigned short keycodes[ARRAY_SIZE(qt2160_key2code)];
    u16 key_matrix;
};

static int qt2160_read_block(struct i2c_client *client,
                 u8 inireg, u8 *buffer, unsigned int count)
{
    int error, idx = 0;

    /*
     * Can't use SMBus block data read. Check for I2C functionality to speed
     * things up whenever possible. Otherwise we will be forced to read
     * sequentially.
     */
    if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {

        error = i2c_smbus_write_byte(client, inireg + idx);
        if (error) {
            dev_err(&client->dev,
                "couldn't send request. Returned %d\n", error);
            return error;
        }

        error = i2c_master_recv(client, buffer, count);
        if (error != count) {
            dev_err(&client->dev,
                "couldn't read registers. Returned %d bytes\n", error);
            return error;
        }
    } else {

        while (count--) {
            int data;

            error = i2c_smbus_write_byte(client, inireg + idx);
            if (error) {
                dev_err(&client->dev,
                    "couldn't send request. Returned %d\n", error);
                return error;
            }

            data = i2c_smbus_read_byte(client);
            if (data < 0) {
                dev_err(&client->dev,
                    "couldn't read register. Returned %d\n", data);
                return data;
            }

            buffer[idx++] = data;
        }
    }

    return 0;
}

static int qt2160_get_key_matrix(struct qt2160_data *qt2160)
{
    struct i2c_client *client = qt2160->client;
    struct input_dev *input = qt2160->input;
    u8 regs[6];
    u16 old_matrix, new_matrix;
    int ret, i, mask;

    dev_dbg(&client->dev, "requesting keys...\n");

    /*
     * Read all registers from General Status Register
     * to GPIOs register
     */
    ret = qt2160_read_block(client, QT2160_CMD_GSTAT, regs, 6);
    if (ret) {
        dev_err(&client->dev,
            "could not perform chip read.\n");
        return ret;
    }

    old_matrix = qt2160->key_matrix;
    qt2160->key_matrix = new_matrix = (regs[2] << 8) | regs[1];

    mask = 0x01;
    for (i = 0; i < 16; ++i, mask <<= 1) {
        int keyval = new_matrix & mask;

        if ((old_matrix & mask) != keyval) {
            input_report_key(input, qt2160->keycodes[i], keyval);
            dev_dbg(&client->dev, "key %d %s\n",
                i, keyval ? "pressed" : "released");
        }
    }

    input_sync(input);

    return 0;
}

static irqreturn_t qt2160_irq(int irq, void *_qt2160)
{
    struct qt2160_data *qt2160 = _qt2160;
    unsigned long flags;

    spin_lock_irqsave(&qt2160->lock, flags);

    mod_delayed_work(system_wq, &qt2160->dwork, 0);

    spin_unlock_irqrestore(&qt2160->lock, flags);

    return IRQ_HANDLED;
}

static void qt2160_schedule_read(struct qt2160_data *qt2160)
{
    spin_lock_irq(&qt2160->lock);
    schedule_delayed_work(&qt2160->dwork, QT2160_CYCLE_INTERVAL);
    spin_unlock_irq(&qt2160->lock);
}

static void qt2160_worker(struct work_struct *work)
{
    struct qt2160_data *qt2160 =
        container_of(work, struct qt2160_data, dwork.work);

    dev_dbg(&qt2160->client->dev, "worker\n");

    qt2160_get_key_matrix(qt2160);

    /* Avoid device lock up by checking every so often */
    qt2160_schedule_read(qt2160);
}

static int __devinit qt2160_read(struct i2c_client *client, u8 reg)
{
    int ret;

    ret = i2c_smbus_write_byte(client, reg);
    if (ret) {
        dev_err(&client->dev,
            "couldn't send request. Returned %d\n", ret);
        return ret;
    }

    ret = i2c_smbus_read_byte(client);
    if (ret < 0) {
        dev_err(&client->dev,
            "couldn't read register. Returned %d\n", ret);
        return ret;
    }

    return ret;
}

static int __devinit qt2160_write(struct i2c_client *client, u8 reg, u8 data)
{
    int error;

    error = i2c_smbus_write_byte(client, reg);
    if (error) {
        dev_err(&client->dev,
            "couldn't send request. Returned %d\n", error);
        return error;
    }

    error = i2c_smbus_write_byte(client, data);
    if (error) {
        dev_err(&client->dev,
            "couldn't write data. Returned %d\n", error);
        return error;
    }

    return error;
}


static bool __devinit qt2160_identify(struct i2c_client *client)
{
    int id, ver, rev;

    /* Read Chid ID to check if chip is valid */
    id = qt2160_read(client, QT2160_CMD_CHIPID);
    if (id != QT2160_VALID_CHIPID) {
        dev_err(&client->dev, "ID %d not supported\n", id);
        return false;
    }

    /* Read chip firmware version */
    ver = qt2160_read(client, QT2160_CMD_CODEVER);
    if (ver < 0) {
        dev_err(&client->dev, "could not get firmware version\n");
        return false;
    }

    /* Read chip firmware revision */
    rev = qt2160_read(client, QT2160_CMD_SUBVER);
    if (rev < 0) {
        dev_err(&client->dev, "could not get firmware revision\n");
        return false;
    }

    dev_info(&client->dev, "AT42QT2160 firmware version %d.%d.%d\n",
            ver >> 4, ver & 0xf, rev);

    return true;
}

static int __devinit qt2160_probe(struct i2c_client *client,
                  const struct i2c_device_id *id)
{
    struct qt2160_data *qt2160;
    struct input_dev *input;
    int i;
    int error;

    /* Check functionality */
    error = i2c_check_functionality(client->adapter,
            I2C_FUNC_SMBUS_BYTE);
    if (!error) {
        dev_err(&client->dev, "%s adapter not supported\n",
                dev_driver_string(&client->adapter->dev));
        return -ENODEV;
    }

    if (!qt2160_identify(client))
        return -ENODEV;

    /* Chip is valid and active. Allocate structure */
    qt2160 = kzalloc(sizeof(struct qt2160_data), GFP_KERNEL);
    input = input_allocate_device();
    if (!qt2160 || !input) {
        dev_err(&client->dev, "insufficient memory\n");
        error = -ENOMEM;
        goto err_free_mem;
    }

    qt2160->client = client;
    qt2160->input = input;
    INIT_DELAYED_WORK(&qt2160->dwork, qt2160_worker);
    spin_lock_init(&qt2160->lock);

    input->name = "AT42QT2160 Touch Sense Keyboard";
    input->id.bustype = BUS_I2C;

    input->keycode = qt2160->keycodes;
    input->keycodesize = sizeof(qt2160->keycodes[0]);
    input->keycodemax = ARRAY_SIZE(qt2160_key2code);

    __set_bit(EV_KEY, input->evbit);
    __clear_bit(EV_REP, input->evbit);
    for (i = 0; i < ARRAY_SIZE(qt2160_key2code); i++) {
        qt2160->keycodes[i] = qt2160_key2code[i];
        __set_bit(qt2160_key2code[i], input->keybit);
    }
    __clear_bit(KEY_RESERVED, input->keybit);

    /* Calibrate device */
    error = qt2160_write(client, QT2160_CMD_CALIBRATE, 1);
    if (error) {
        dev_err(&client->dev, "failed to calibrate device\n");
        goto err_free_mem;
    }

    if (client->irq) {
        error = request_irq(client->irq, qt2160_irq,
                    IRQF_TRIGGER_FALLING, "qt2160", qt2160);
        if (error) {
            dev_err(&client->dev,
                "failed to allocate irq %d\n", client->irq);
            goto err_free_mem;
        }
    }

    error = input_register_device(qt2160->input);
    if (error) {
        dev_err(&client->dev,
            "Failed to register input device\n");
        goto err_free_irq;
    }

    i2c_set_clientdata(client, qt2160);
    qt2160_schedule_read(qt2160);

    return 0;

err_free_irq:
    if (client->irq)
        free_irq(client->irq, qt2160);
err_free_mem:
    input_free_device(input);
    kfree(qt2160);
    return error;
}

static int __devexit qt2160_remove(struct i2c_client *client)
{
    struct qt2160_data *qt2160 = i2c_get_clientdata(client);

    /* Release IRQ so no queue will be scheduled */
    if (client->irq)
        free_irq(client->irq, qt2160);

    cancel_delayed_work_sync(&qt2160->dwork);

    input_unregister_device(qt2160->input);
    kfree(qt2160);

    return 0;
}

static const struct i2c_device_id qt2160_idtable[] = {
    { "qt2160", 0, },
    { }
};

MODULE_DEVICE_TABLE(i2c, qt2160_idtable);

static struct i2c_driver qt2160_driver = {
    .driver = {
        .name   = "qt2160",
        .owner  = THIS_MODULE,
    },

    .id_table   = qt2160_idtable,
    .probe      = qt2160_probe,
    .remove     = __devexit_p(qt2160_remove),
};

module_i2c_driver(qt2160_driver);

MODULE_AUTHOR("Raphael Derosso Pereira <[email protected]>");
MODULE_DESCRIPTION("Driver for AT42QT2160 Touch Sensor");
MODULE_LICENSE("GPL");