/*
 *  qt2160.c - Atmel AT42QT2160 Touch Sense Controller
 *
 *  Copyright (C) 2009 Raphael Derosso Pereira <raphaelpereira@gmail.com>
 *
 *  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 <raphaelpereira@gmail.com>");
MODULE_DESCRIPTION("Driver for AT42QT2160 Touch Sensor");
MODULE_LICENSE("GPL");