/*
 * Driver for MAXI MAX11801 - A Resistive touch screen controller with
 * i2c interface
 *
 * Copyright (C) 2011 Freescale Semiconductor, Inc.
 * Author: Zhang Jiejing <jiejing.zhang@freescale.com>
 *
 * 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/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 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 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 = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
        input_dev = devm_input_allocate_device(&client->dev);
        if (!data || !input_dev) {
                dev_err(&client->dev, "Failed to allocate memory\n");
                return -ENOMEM;
        }

        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);

        max11801_ts_phy_init(data);

        error = devm_request_threaded_irq(&client->dev, 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");
                return error;
        }

        error = input_register_device(data->input_dev);
        if (error)
                return error;

        return 0;
}

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

static const struct of_device_id max11801_ts_dt_ids[] = {
        { .compatible = "maxim,max11801" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, max11801_ts_dt_ids);

static struct i2c_driver max11801_ts_driver = {
        .driver = {
                .name   = "max11801_ts",
                .of_match_table = max11801_ts_dt_ids,
        },
        .id_table       = max11801_ts_id,
        .probe          = max11801_ts_probe,
};

module_i2c_driver(max11801_ts_driver);

MODULE_AUTHOR("Zhang Jiejing <jiejing.zhang@freescale.com>");
MODULE_DESCRIPTION("Touchscreen driver for MAXI MAX11801 controller");
MODULE_LICENSE("GPL");