/*
 * drivers/input/touchscreen/tsc2007.c
 *
 * Copyright (c) 2008 MtekVision Co., Ltd.
 *      Kwangwoo Lee <kwlee@mtekvision.com>
 *
 * Using code from:
 *  - ads7846.c
 *      Copyright (c) 2005 David Brownell
 *      Copyright (c) 2006 Nokia Corporation
 *  - corgi_ts.c
 *      Copyright (C) 2004-2005 Richard Purdie
 *  - omap_ts.[hc], ads7846.h, ts_osk.c
 *      Copyright (C) 2002 MontaVista Software
 *      Copyright (C) 2004 Texas Instruments
 *      Copyright (C) 2005 Dirk Behme
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/i2c/tsc2007.h>

#define TS_POLL_DELAY   (10 * 1000)     /* ns delay before the first sample */
#define TS_POLL_PERIOD  (5 * 1000)      /* ns delay between samples */

#define TSC2007_MEASURE_TEMP0           (0x0 << 4)
#define TSC2007_MEASURE_AUX             (0x2 << 4)
#define TSC2007_MEASURE_TEMP1           (0x4 << 4)
#define TSC2007_ACTIVATE_XN             (0x8 << 4)
#define TSC2007_ACTIVATE_YN             (0x9 << 4)
#define TSC2007_ACTIVATE_YP_XN          (0xa << 4)
#define TSC2007_SETUP                   (0xb << 4)
#define TSC2007_MEASURE_X               (0xc << 4)
#define TSC2007_MEASURE_Y               (0xd << 4)
#define TSC2007_MEASURE_Z1              (0xe << 4)
#define TSC2007_MEASURE_Z2              (0xf << 4)

#define TSC2007_POWER_OFF_IRQ_EN        (0x0 << 2)
#define TSC2007_ADC_ON_IRQ_DIS0         (0x1 << 2)
#define TSC2007_ADC_OFF_IRQ_EN          (0x2 << 2)
#define TSC2007_ADC_ON_IRQ_DIS1         (0x3 << 2)

#define TSC2007_12BIT                   (0x0 << 1)
#define TSC2007_8BIT                    (0x1 << 1)

#define MAX_12BIT                       ((1 << 12) - 1)

#define ADC_ON_12BIT    (TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)

#define READ_Y          (ADC_ON_12BIT | TSC2007_MEASURE_Y)
#define READ_Z1         (ADC_ON_12BIT | TSC2007_MEASURE_Z1)
#define READ_Z2         (ADC_ON_12BIT | TSC2007_MEASURE_Z2)
#define READ_X          (ADC_ON_12BIT | TSC2007_MEASURE_X)
#define PWRDOWN         (TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)

struct ts_event {
        u16     x;
        u16     y;
        u16     z1, z2;
};

struct tsc2007 {
        struct input_dev        *input;
        char                    phys[32];
        struct hrtimer          timer;
        struct ts_event         tc;

        struct i2c_client       *client;

        spinlock_t              lock;

        u16                     model;
        u16                     x_plate_ohms;

        unsigned                pendown;
        int                     irq;

        int                     (*get_pendown_state)(void);
        void                    (*clear_penirq)(void);
};

static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
{
        s32 data;
        u16 val;

        data = i2c_smbus_read_word_data(tsc->client, cmd);
        if (data < 0) {
                dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
                return data;
        }

        /* The protocol and raw data format from i2c interface:
         * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
         * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
         */
        val = swab16(data) >> 4;

        dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);

        return val;
}

static void tsc2007_send_event(void *tsc)
{
        struct tsc2007  *ts = tsc;
        u32             rt;
        u16             x, y, z1, z2;

        x = ts->tc.x;
        y = ts->tc.y;
        z1 = ts->tc.z1;
        z2 = ts->tc.z2;

        /* range filtering */
        if (x == MAX_12BIT)
                x = 0;

        if (likely(x && z1)) {
                /* compute touch pressure resistance using equation #1 */
                rt = z2;
                rt -= z1;
                rt *= x;
                rt *= ts->x_plate_ohms;
                rt /= z1;
                rt = (rt + 2047) >> 12;
        } else
                rt = 0;

        /* Sample found inconsistent by debouncing or pressure is beyond
         * the maximum. Don't report it to user space, repeat at least
         * once more the measurement
         */
        if (rt > MAX_12BIT) {
                dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);

                hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
                              HRTIMER_MODE_REL);
                return;
        }

        /* NOTE: We can't rely on the pressure to determine the pen down
         * state, even this controller has a pressure sensor.  The pressure
         * value can fluctuate for quite a while after lifting the pen and
         * in some cases may not even settle at the expected value.
         *
         * The only safe way to check for the pen up condition is in the
         * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
         */
        if (rt) {
                struct input_dev *input = ts->input;

                if (!ts->pendown) {
                        dev_dbg(&ts->client->dev, "DOWN\n");

                        input_report_key(input, BTN_TOUCH, 1);
                        ts->pendown = 1;
                }

                input_report_abs(input, ABS_X, x);
                input_report_abs(input, ABS_Y, y);
                input_report_abs(input, ABS_PRESSURE, rt);

                input_sync(input);

                dev_dbg(&ts->client->dev, "point(%4d,%4d), pressure (%4u)\n",
                        x, y, rt);
        }

        hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
                        HRTIMER_MODE_REL);
}

static int tsc2007_read_values(struct tsc2007 *tsc)
{
        /* y- still on; turn on only y+ (and ADC) */
        tsc->tc.y = tsc2007_xfer(tsc, READ_Y);

        /* turn y- off, x+ on, then leave in lowpower */
        tsc->tc.x = tsc2007_xfer(tsc, READ_X);

        /* turn y+ off, x- on; we'll use formula #1 */
        tsc->tc.z1 = tsc2007_xfer(tsc, READ_Z1);
        tsc->tc.z2 = tsc2007_xfer(tsc, READ_Z2);

        /* power down */
        tsc2007_xfer(tsc, PWRDOWN);

        return 0;
}

static enum hrtimer_restart tsc2007_timer(struct hrtimer *handle)
{
        struct tsc2007 *ts = container_of(handle, struct tsc2007, timer);
        unsigned long flags;

        spin_lock_irqsave(&ts->lock, flags);

        if (unlikely(!ts->get_pendown_state() && ts->pendown)) {
                struct input_dev *input = ts->input;

                dev_dbg(&ts->client->dev, "UP\n");

                input_report_key(input, BTN_TOUCH, 0);
                input_report_abs(input, ABS_PRESSURE, 0);
                input_sync(input);

                ts->pendown = 0;
                enable_irq(ts->irq);
        } else {
                /* pen is still down, continue with the measurement */
                dev_dbg(&ts->client->dev, "pen is still down\n");

                tsc2007_read_values(ts);
                tsc2007_send_event(ts);
        }

        spin_unlock_irqrestore(&ts->lock, flags);

        return HRTIMER_NORESTART;
}

static irqreturn_t tsc2007_irq(int irq, void *handle)
{
        struct tsc2007 *ts = handle;
        unsigned long flags;

        spin_lock_irqsave(&ts->lock, flags);

        if (likely(ts->get_pendown_state())) {
                disable_irq_nosync(ts->irq);
                hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
                                        HRTIMER_MODE_REL);
        }

        if (ts->clear_penirq)
                ts->clear_penirq();

        spin_unlock_irqrestore(&ts->lock, flags);

        return IRQ_HANDLED;
}

static int tsc2007_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct tsc2007 *ts;
        struct tsc2007_platform_data *pdata = pdata = client->dev.platform_data;
        struct input_dev *input_dev;
        int err;

        if (!pdata) {
                dev_err(&client->dev, "platform data is required!\n");
                return -EINVAL;
        }

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_READ_WORD_DATA))
                return -EIO;

        ts = kzalloc(sizeof(struct tsc2007), GFP_KERNEL);
        input_dev = input_allocate_device();
        if (!ts || !input_dev) {
                err = -ENOMEM;
                goto err_free_mem;
        }

        ts->client = client;
        i2c_set_clientdata(client, ts);

        ts->input = input_dev;

        hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
        ts->timer.function = tsc2007_timer;

        spin_lock_init(&ts->lock);

        ts->model             = pdata->model;
        ts->x_plate_ohms      = pdata->x_plate_ohms;
        ts->get_pendown_state = pdata->get_pendown_state;
        ts->clear_penirq      = pdata->clear_penirq;

        pdata->init_platform_hw();

        snprintf(ts->phys, sizeof(ts->phys),
                 "%s/input0", dev_name(&client->dev));

        input_dev->name = "TSC2007 Touchscreen";
        input_dev->phys = ts->phys;
        input_dev->id.bustype = BUS_I2C;

        input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
        input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

        input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
        input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
        input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);

        tsc2007_read_values(ts);

        ts->irq = client->irq;

        err = request_irq(ts->irq, tsc2007_irq, 0,
                        client->dev.driver->name, ts);
        if (err < 0) {
                dev_err(&client->dev, "irq %d busy?\n", ts->irq);
                goto err_free_mem;
        }

        err = input_register_device(input_dev);
        if (err)
                goto err_free_irq;

        dev_info(&client->dev, "registered with irq (%d)\n", ts->irq);

        return 0;

 err_free_irq:
        free_irq(ts->irq, ts);
        hrtimer_cancel(&ts->timer);
 err_free_mem:
        input_free_device(input_dev);
        kfree(ts);
        return err;
}

static int tsc2007_remove(struct i2c_client *client)
{
        struct tsc2007  *ts = i2c_get_clientdata(client);
        struct tsc2007_platform_data *pdata;

        pdata = client->dev.platform_data;
        pdata->exit_platform_hw();

        free_irq(ts->irq, ts);
        hrtimer_cancel(&ts->timer);
        input_unregister_device(ts->input);
        kfree(ts);

        return 0;
}

static struct i2c_device_id tsc2007_idtable[] = {
        { "tsc2007", 0 },
        { }
};

MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);

static struct i2c_driver tsc2007_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = "tsc2007"
        },
        .id_table       = tsc2007_idtable,
        .probe          = tsc2007_probe,
        .remove         = tsc2007_remove,
};

static int __init tsc2007_init(void)
{
        return i2c_add_driver(&tsc2007_driver);
}

static void __exit tsc2007_exit(void)
{
        i2c_del_driver(&tsc2007_driver);
}

module_init(tsc2007_init);
module_exit(tsc2007_exit);

MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
MODULE_LICENSE("GPL");