max11801_ts.c

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/*
 * Driver for MAXI MAX11801 - A Resistive touch screen controller with
 * i2c interface
 *
 * Copyright (C) 2011 Freescale Semiconductor, Inc.
 * Author: Zhang Jiejing <[email protected]>
 *
 * Based on mcs5000_ts.c
 *
 * 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 driver aims to support the series of MAXI touch chips max11801
 * through max11803. The main difference between these 4 chips can be
 * found in the table below:
 * -----------------------------------------------------
 * | CHIP     |  AUTO MODE SUPPORT(FIFO) | INTERFACE    |
 * |----------------------------------------------------|
 * | max11800 |  YES                     |   SPI        |
 * | max11801 |  YES                     |   I2C        |
 * | max11802 |  NO                      |   SPI        |
 * | max11803 |  NO                      |   I2C        |
 * ------------------------------------------------------
 *
 * Currently, this driver only supports max11801.
 *
 * Data Sheet:
 * http://www.maxim-ic.com/datasheet/index.mvp/id/5943
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/bitops.h>

/* Register Address define */
#define GENERNAL_STATUS_REG     0x00
#define GENERNAL_CONF_REG       0x01
#define MESURE_RES_CONF_REG     0x02
#define MESURE_AVER_CONF_REG        0x03
#define ADC_SAMPLE_TIME_CONF_REG    0x04
#define PANEL_SETUPTIME_CONF_REG    0x05
#define DELAY_CONVERSION_CONF_REG   0x06
#define TOUCH_DETECT_PULLUP_CONF_REG    0x07
#define AUTO_MODE_TIME_CONF_REG     0x08 /* only for max11800/max11801 */
#define APERTURE_CONF_REG       0x09 /* only for max11800/max11801 */
#define AUX_MESURE_CONF_REG     0x0a
#define OP_MODE_CONF_REG        0x0b

/* FIFO is found only in max11800 and max11801 */
#define FIFO_RD_CMD         (0x50 << 1)
#define MAX11801_FIFO_INT       (1 << 2)
#define MAX11801_FIFO_OVERFLOW      (1 << 3)

#define XY_BUFSIZE          4
#define XY_BUF_OFFSET           4

#define MAX11801_MAX_X          0xfff
#define MAX11801_MAX_Y          0xfff

#define MEASURE_TAG_OFFSET      2
#define MEASURE_TAG_MASK        (3 << MEASURE_TAG_OFFSET)
#define EVENT_TAG_OFFSET        0
#define EVENT_TAG_MASK          (3 << EVENT_TAG_OFFSET)
#define MEASURE_X_TAG           (0 << MEASURE_TAG_OFFSET)
#define MEASURE_Y_TAG           (1 << MEASURE_TAG_OFFSET)

/* These are the state of touch event state machine */
enum {
    EVENT_INIT,
    EVENT_MIDDLE,
    EVENT_RELEASE,
    EVENT_FIFO_END
};

struct max11801_data {
    struct i2c_client       *client;
    struct input_dev        *input_dev;
};

static u8 read_register(struct i2c_client *client, int addr)
{
    /* XXX: The chip ignores LSB of register address */
    return i2c_smbus_read_byte_data(client, addr << 1);
}

static int max11801_write_reg(struct i2c_client *client, int addr, int data)
{
    /* XXX: The chip ignores LSB of register address */
    return i2c_smbus_write_byte_data(client, addr << 1, data);
}

static irqreturn_t max11801_ts_interrupt(int irq, void *dev_id)
{
    struct max11801_data *data = dev_id;
    struct i2c_client *client = data->client;
    int status, i, ret;
    u8 buf[XY_BUFSIZE];
    int x = -1;
    int y = -1;

    status = read_register(data->client, GENERNAL_STATUS_REG);

    if (status & (MAX11801_FIFO_INT | MAX11801_FIFO_OVERFLOW)) {
        status = read_register(data->client, GENERNAL_STATUS_REG);

        ret = i2c_smbus_read_i2c_block_data(client, FIFO_RD_CMD,
                            XY_BUFSIZE, buf);

        /*
         * We should get 4 bytes buffer that contains X,Y
         * and event tag
         */
        if (ret < XY_BUFSIZE)
            goto out;

        for (i = 0; i < XY_BUFSIZE; i += XY_BUFSIZE / 2) {
            if ((buf[i + 1] & MEASURE_TAG_MASK) == MEASURE_X_TAG)
                x = (buf[i] << XY_BUF_OFFSET) +
                    (buf[i + 1] >> XY_BUF_OFFSET);
            else if ((buf[i + 1] & MEASURE_TAG_MASK) == MEASURE_Y_TAG)
                y = (buf[i] << XY_BUF_OFFSET) +
                    (buf[i + 1] >> XY_BUF_OFFSET);
        }

        if ((buf[1] & EVENT_TAG_MASK) != (buf[3] & EVENT_TAG_MASK))
            goto out;

        switch (buf[1] & EVENT_TAG_MASK) {
        case EVENT_INIT:
            /* fall through */
        case EVENT_MIDDLE:
            input_report_abs(data->input_dev, ABS_X, x);
            input_report_abs(data->input_dev, ABS_Y, y);
            input_event(data->input_dev, EV_KEY, BTN_TOUCH, 1);
            input_sync(data->input_dev);
            break;

        case EVENT_RELEASE:
            input_event(data->input_dev, EV_KEY, BTN_TOUCH, 0);
            input_sync(data->input_dev);
            break;

        case EVENT_FIFO_END:
            break;
        }
    }
out:
    return IRQ_HANDLED;
}

static void __devinit max11801_ts_phy_init(struct max11801_data *data)
{
    struct i2c_client *client = data->client;

    /* Average X,Y, take 16 samples, average eight media sample */
    max11801_write_reg(client, MESURE_AVER_CONF_REG, 0xff);
    /* X,Y panel setup time set to 20us */
    max11801_write_reg(client, PANEL_SETUPTIME_CONF_REG, 0x11);
    /* Rough pullup time (2uS), Fine pullup time (10us)  */
    max11801_write_reg(client, TOUCH_DETECT_PULLUP_CONF_REG, 0x10);
    /* Auto mode init period = 5ms , scan period = 5ms*/
    max11801_write_reg(client, AUTO_MODE_TIME_CONF_REG, 0xaa);
    /* Aperture X,Y set to +- 4LSB */
    max11801_write_reg(client, APERTURE_CONF_REG, 0x33);
    /* Enable Power, enable Automode, enable Aperture, enable Average X,Y */
    max11801_write_reg(client, OP_MODE_CONF_REG, 0x36);
}

static int __devinit max11801_ts_probe(struct i2c_client *client,
                       const struct i2c_device_id *id)
{
    struct max11801_data *data;
    struct input_dev *input_dev;
    int error;

    data = kzalloc(sizeof(struct max11801_data), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!data || !input_dev) {
        dev_err(&client->dev, "Failed to allocate memory\n");
        error = -ENOMEM;
        goto err_free_mem;
    }

    data->client = client;
    data->input_dev = input_dev;

    input_dev->name = "max11801_ts";
    input_dev->id.bustype = BUS_I2C;
    input_dev->dev.parent = &client->dev;

    __set_bit(EV_ABS, input_dev->evbit);
    __set_bit(EV_KEY, input_dev->evbit);
    __set_bit(BTN_TOUCH, input_dev->keybit);
    input_set_abs_params(input_dev, ABS_X, 0, MAX11801_MAX_X, 0, 0);
    input_set_abs_params(input_dev, ABS_Y, 0, MAX11801_MAX_Y, 0, 0);
    input_set_drvdata(input_dev, data);

    max11801_ts_phy_init(data);

    error = request_threaded_irq(client->irq, NULL, max11801_ts_interrupt,
                     IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                     "max11801_ts", data);
    if (error) {
        dev_err(&client->dev, "Failed to register interrupt\n");
        goto err_free_mem;
    }

    error = input_register_device(data->input_dev);
    if (error)
        goto err_free_irq;

    i2c_set_clientdata(client, data);
    return 0;

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

static __devexit int max11801_ts_remove(struct i2c_client *client)
{
    struct max11801_data *data = i2c_get_clientdata(client);

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

    return 0;
}

static const struct i2c_device_id max11801_ts_id[] = {
    {"max11801", 0},
    { }
};
MODULE_DEVICE_TABLE(i2c, max11801_ts_id);

static struct i2c_driver max11801_ts_driver = {
    .driver = {
        .name   = "max11801_ts",
        .owner  = THIS_MODULE,
    },
    .id_table   = max11801_ts_id,
    .probe      = max11801_ts_probe,
    .remove     = __devexit_p(max11801_ts_remove),
};

module_i2c_driver(max11801_ts_driver);

MODULE_AUTHOR("Zhang Jiejing <[email protected]>");
MODULE_DESCRIPTION("Touchscreen driver for MAXI MAX11801 controller");
MODULE_LICENSE("GPL");