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

#define TS_POLL_DELAY                   1 /* ms delay between samples */
#define TS_POLL_PERIOD                  1 /* ms 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 delayed_work     work;

        struct i2c_client       *client;

        u16                     model;
        u16                     x_plate_ohms;

        bool                    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_read_values(struct tsc2007 *tsc, struct ts_event *tc)
{
        /* y- still on; turn on only y+ (and ADC) */
        tc->y = tsc2007_xfer(tsc, READ_Y);

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

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

        /* Prepare for next touch reading - power down ADC, enable PENIRQ */
        tsc2007_xfer(tsc, PWRDOWN);
}

static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
{
        u32 rt = 0;

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

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

        return rt;
}

static void tsc2007_send_up_event(struct tsc2007 *tsc)
{
        struct input_dev *input = tsc->input;

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

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

static void tsc2007_work(struct work_struct *work)
{
        struct tsc2007 *ts =
                container_of(to_delayed_work(work), struct tsc2007, work);
        struct ts_event tc;
        u32 rt;

        /*
         * NOTE: We can't rely on the pressure to determine the pen down
         * state, even though 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
         * work function by reading the pen signal state (it's a GPIO
         * and IRQ). Unfortunately such callback is not always available,
         * in that case we have rely on the pressure anyway.
         */
        if (ts->get_pendown_state) {
                if (unlikely(!ts->get_pendown_state())) {
                        tsc2007_send_up_event(ts);
                        ts->pendown = false;
                        goto out;
                }

                dev_dbg(&ts->client->dev, "pen is still down\n");
        }

        tsc2007_read_values(ts, &tc);

        rt = tsc2007_calculate_pressure(ts, &tc);
        if (rt > MAX_12BIT) {
                /*
                 * 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.
                 */
                dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
                goto out;

        }

        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 = true;
                }

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

                input_sync(input);

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

        } else if (!ts->get_pendown_state && ts->pendown) {
                /*
                 * We don't have callback to check pendown state, so we
                 * have to assume that since pressure reported is 0 the
                 * pen was lifted up.
                 */
                tsc2007_send_up_event(ts);
                ts->pendown = false;
        }

 out:
        if (ts->pendown)
                schedule_delayed_work(&ts->work,
                                      msecs_to_jiffies(TS_POLL_PERIOD));
        else
                enable_irq(ts->irq);
}

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

        if (!ts->get_pendown_state || likely(ts->get_pendown_state())) {
                disable_irq_nosync(ts->irq);
                schedule_delayed_work(&ts->work,
                                      msecs_to_jiffies(TS_POLL_DELAY));
        }

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

        return IRQ_HANDLED;
}

static void tsc2007_free_irq(struct tsc2007 *ts)
{
        free_irq(ts->irq, ts);
        if (cancel_delayed_work_sync(&ts->work)) {
                /*
                 * Work was pending, therefore we need to enable
                 * IRQ here to balance the disable_irq() done in the
                 * interrupt handler.
                 */
                enable_irq(ts->irq);
        }
}

static int __devinit tsc2007_probe(struct i2c_client *client,
                                   const struct i2c_device_id *id)
{
        struct tsc2007 *ts;
        struct tsc2007_platform_data *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;
        ts->irq = client->irq;
        ts->input = input_dev;
        INIT_DELAYED_WORK(&ts->work, tsc2007_work);

        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;

        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);

        if (pdata->init_platform_hw)
                pdata->init_platform_hw();

        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;
        }

        /* Prepare for touch readings - power down ADC and enable PENIRQ */
        err = tsc2007_xfer(ts, PWRDOWN);
        if (err < 0)
                goto err_free_irq;

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

        i2c_set_clientdata(client, ts);

        return 0;

 err_free_irq:
        tsc2007_free_irq(ts);
        if (pdata->exit_platform_hw)
                pdata->exit_platform_hw();
 err_free_mem:
        input_free_device(input_dev);
        kfree(ts);
        return err;
}

static int __devexit tsc2007_remove(struct i2c_client *client)
{
        struct tsc2007  *ts = i2c_get_clientdata(client);
        struct tsc2007_platform_data *pdata = client->dev.platform_data;

        tsc2007_free_irq(ts);

        if (pdata->exit_platform_hw)
                pdata->exit_platform_hw();

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

        return 0;
}

static const 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         = __devexit_p(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");