#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>

#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>

#define QT2120_VALID_CHIPID  0x3E

#define QT2120_CMD_CHIPID     0
#define QT2120_CMD_CODEVER    1
#define QT2120_CMD_GSTAT      2
#define QT2120_CMD_KEYS3      3
#define QT2120_CMD_KEYS4      4
#define QT2120_CMD_SLIDE      5
#define QT2120_CMD_CALIBRATE  6
#define QT2120_CMD_RESET      7

#define QT2120_CYCLE_INTERVAL	(2*HZ)

static unsigned char qt2120_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 qt2120_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(qt2120_key2code)];
	u16 key_matrix;
	unsigned irq_gpio;
	u32 irq_flags;
};

static int qt2120_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 qt2120_get_key_matrix(struct qt2120_data *qt2120)
{
	struct i2c_client *client = qt2120->client;
	struct input_dev *input = qt2120->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 = qt2120_read_block(client, QT2120_CMD_GSTAT, regs, 6);
	if (ret) {
		dev_err(&client->dev,
			"could not perform chip read.\n");
		return ret;
	}

	old_matrix = qt2120->key_matrix;
	qt2120->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, qt2120->keycodes[i], keyval);
			dev_dbg(&client->dev, "key %d %s\n",
				i, keyval ? "pressed" : "released");
		}
	}

	input_sync(input);

	return 0;
}

static irqreturn_t qt2120_irq(int irq, void *_qt2120)
{
	struct qt2120_data *qt2120 = _qt2120;
	unsigned long flags;

	spin_lock_irqsave(&qt2120->lock, flags);

	__cancel_delayed_work(&qt2120->dwork);
	schedule_delayed_work(&qt2120->dwork, 0);

	spin_unlock_irqrestore(&qt2120->lock, flags);

	return IRQ_HANDLED;
}

static void qt2120_schedule_read(struct qt2120_data *qt2120)
{
	spin_lock_irq(&qt2120->lock);
	schedule_delayed_work(&qt2120->dwork, QT2120_CYCLE_INTERVAL);
	spin_unlock_irq(&qt2120->lock);
}

static void qt2120_worker(struct work_struct *work)
{
	struct qt2120_data *qt2120 =
		container_of(work, struct qt2120_data, dwork.work);

	dev_dbg(&qt2120->client->dev, "worker\n");

	qt2120_get_key_matrix(qt2120);

	/* Avoid device lock up by checking every so often */
	qt2120_schedule_read(qt2120);
}

static int __devinit qt2120_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 qt2120_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 qt2120_identify(struct i2c_client *client)
{
	int id, ver;

	/* Read Chid ID to check if chip is valid */
	id = qt2120_read(client, QT2120_CMD_CHIPID);
	printk("qt2120 ChipID %d \n", id);

	if (id != QT2120_VALID_CHIPID) {
		dev_err(&client->dev, "ID %d not supported\n", id);
		return false;
	}

	/* Read chip firmware version */
	ver = qt2120_read(client, QT2120_CMD_CODEVER);
	if (ver < 0) {
		dev_err(&client->dev, "could not get firmware version\n");
		return false;
	}

	dev_info(&client->dev, "AT42QT2120 firmware version %d\n",ver);

	return true;
}

static int qt2120_parse_dt(struct device *dev,
	struct qt2120_data *pdata)
{
    struct device_node *np = dev->of_node;

    /* irq gpio info */
    pdata->irq_gpio = of_get_named_gpio_flags(np,
	    "qt2120,irq-gpio", 0, &pdata->irq_flags);

   return 0;
}

static int __devinit qt2120_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
{
    struct qt2120_data *qt2120;
    struct input_dev *input;
    int i;
    int error;

    printk("AT42QT2120 Probe\n");
    /* 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 (!qt2120_identify(client))
	return -ENODEV;

    /* Chip is valid and active. Allocate structure */
    qt2120 = kzalloc(sizeof(struct qt2120_data), GFP_KERNEL);
    input = input_allocate_device();
    if (!qt2120 || !input) {
	dev_err(&client->dev, "insufficient memory\n");
	error = -ENOMEM;
	goto err_free_mem;
    }    

    /* Parse the device tree */
    if (client->dev.of_node) {
	error = qt2120_parse_dt(&client->dev, qt2120);
	if (error)
	    return error;
    }

    qt2120->client = client;
    qt2120->input = input;
    INIT_DELAYED_WORK(&qt2120->dwork, qt2120_worker);
    spin_lock_init(&qt2120->lock);

    input->name = "AT42QT2120 Touch Sense Keyboard";
    input->id.bustype = BUS_I2C;

    input->keycode = qt2120->keycodes;
    input->keycodesize = sizeof(qt2120->keycodes[0]);
    input->keycodemax = ARRAY_SIZE(qt2120_key2code);

    __set_bit(EV_KEY, input->evbit);
    __clear_bit(EV_REP, input->evbit);
    for (i = 0; i < ARRAY_SIZE(qt2120_key2code); i++) {
	qt2120->keycodes[i] = qt2120_key2code[i];
	__set_bit(qt2120_key2code[i], input->keybit);
    }
    __clear_bit(KEY_RESERVED, input->keybit);

    /* Configure irq gpio */
    if (gpio_is_valid(qt2120->irq_gpio)) {
	error = gpio_request(qt2120->irq_gpio, "qt2120_irq_gpio");
	if (error) {
	    dev_err(&client->dev, "unable to request gpio [%d]\n",
		    qt2120->irq_gpio);
	    goto err_free_mem;
	}
	error = gpio_direction_input(qt2120->irq_gpio);
	if (error) {
	    dev_err(&client->dev,
		    "unable to set direction for gpio [%d]\n",
		    qt2120->irq_gpio);
	    goto err_irq_gpio_req;
	}
	client->irq = gpio_to_irq(qt2120->irq_gpio);
    } else {
	dev_err(&client->dev, "irq gpio not provided\n");
	goto err_free_mem;
    }

    /* Calibrate device */
    error = qt2120_write(client, QT2120_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, qt2120_irq,
		IRQF_TRIGGER_FALLING, "qt2120", qt2120);
	if (error) {
	    dev_err(&client->dev,
		    "failed to allocate irq %d\n", client->irq);
	    goto err_free_mem;
	}
    }

    error = input_register_device(qt2120->input);
    if (error) {
	dev_err(&client->dev,
		"Failed to register input device\n");
	goto err_free_irq;
    }

    i2c_set_clientdata(client, qt2120);
    qt2120_schedule_read(qt2120);

    return 0;

err_free_irq:
    if (client->irq)
	free_irq(client->irq, qt2120);
err_irq_gpio_req:
    if (gpio_is_valid(qt2120->irq_gpio))
	gpio_free(qt2120->irq_gpio);
err_free_mem:
    input_free_device(input);
    kfree(qt2120);
    return error;
}

static int __devexit qt2120_remove(struct i2c_client *client)
{
    	struct qt2120_data *qt2120 = i2c_get_clientdata(client);

	/* Release IRQ so no queue will be scheduled */
	if (client->irq)
	    free_irq(client->irq, qt2120);

	cancel_delayed_work_sync(&qt2120->dwork);

	input_unregister_device(qt2120->input);
	kfree(qt2120);

	return 0;
}

static const struct of_device_id qt2120_of_match[] = {  
    { .compatible = "atmel,qt2120", },  
    { }  
}; 

static const struct i2c_device_id qt2120_idtable[] = {
    { "qt2120", 0, },
    { }
};

MODULE_DEVICE_TABLE(i2c, qt2120_idtable); 

static struct i2c_driver qt2120_driver = {
    .driver = {
	.name	= "qt2120",
	.owner  = THIS_MODULE,
	.of_match_table = qt2120_of_match, 
    },

    .id_table	= qt2120_idtable,
    .probe		= qt2120_probe,
    .remove		= __devexit_p(qt2120_remove),
};

static int __init qt2120_init_module(void)
{
    printk("QT2120 init\n");
    return i2c_add_driver(&qt2120_driver);
}

static void __exit qt2120_exit_module(void)
{
    printk("QT2120 del\n");
    i2c_del_driver(&qt2120_driver);
    return;
}

module_init(qt2120_init_module);
module_exit(qt2120_exit_module);

MODULE_AUTHOR("Landy Zhou <landy.zhou@ovt.com>");
MODULE_DESCRIPTION("Driver for AT42QT2120 Touch Sensor");
MODULE_LICENSE("GPL");