tsc2005.c

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/*
 * TSC2005 touchscreen driver
 *
 * Copyright (C) 2006-2010 Nokia Corporation
 *
 * Author: Lauri Leukkunen <[email protected]>
 * based on TSC2301 driver by Klaus K. Pedersen <[email protected]>
 *
 * 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 program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/pm.h>
#include <linux/spi/spi.h>
#include <linux/spi/tsc2005.h>

/*
 * The touchscreen interface operates as follows:
 *
 * 1) Pen is pressed against the touchscreen.
 * 2) TSC2005 performs AD conversion.
 * 3) After the conversion is done TSC2005 drives DAV line down.
 * 4) GPIO IRQ is received and tsc2005_irq_thread() is scheduled.
 * 5) tsc2005_irq_thread() queues up an spi transfer to fetch the x, y, z1, z2
 *    values.
 * 6) tsc2005_irq_thread() reports coordinates to input layer and sets up
 *    tsc2005_penup_timer() to be called after TSC2005_PENUP_TIME_MS (40ms).
 * 7) When the penup timer expires, there have not been touch or DAV interrupts
 *    during the last 40ms which means the pen has been lifted.
 *
 * ESD recovery via a hardware reset is done if the TSC2005 doesn't respond
 * after a configurable period (in ms) of activity. If esd_timeout is 0, the
 * watchdog is disabled.
 */

/* control byte 1 */
#define TSC2005_CMD         0x80
#define TSC2005_CMD_NORMAL      0x00
#define TSC2005_CMD_STOP        0x01
#define TSC2005_CMD_12BIT       0x04

/* control byte 0 */
#define TSC2005_REG_READ        0x0001
#define TSC2005_REG_PND0        0x0002
#define TSC2005_REG_X           0x0000
#define TSC2005_REG_Y           0x0008
#define TSC2005_REG_Z1          0x0010
#define TSC2005_REG_Z2          0x0018
#define TSC2005_REG_TEMP_HIGH       0x0050
#define TSC2005_REG_CFR0        0x0060
#define TSC2005_REG_CFR1        0x0068
#define TSC2005_REG_CFR2        0x0070

/* configuration register 0 */
#define TSC2005_CFR0_PRECHARGE_276US    0x0040
#define TSC2005_CFR0_STABTIME_1MS   0x0300
#define TSC2005_CFR0_CLOCK_1MHZ     0x1000
#define TSC2005_CFR0_RESOLUTION12   0x2000
#define TSC2005_CFR0_PENMODE        0x8000
#define TSC2005_CFR0_INITVALUE      (TSC2005_CFR0_STABTIME_1MS    | \
                     TSC2005_CFR0_CLOCK_1MHZ      | \
                     TSC2005_CFR0_RESOLUTION12    | \
                     TSC2005_CFR0_PRECHARGE_276US | \
                     TSC2005_CFR0_PENMODE)

/* bits common to both read and write of configuration register 0 */
#define TSC2005_CFR0_RW_MASK        0x3fff

/* configuration register 1 */
#define TSC2005_CFR1_BATCHDELAY_4MS 0x0003
#define TSC2005_CFR1_INITVALUE      TSC2005_CFR1_BATCHDELAY_4MS

/* configuration register 2 */
#define TSC2005_CFR2_MAVE_Z     0x0004
#define TSC2005_CFR2_MAVE_Y     0x0008
#define TSC2005_CFR2_MAVE_X     0x0010
#define TSC2005_CFR2_AVG_7      0x0800
#define TSC2005_CFR2_MEDIUM_15      0x3000
#define TSC2005_CFR2_INITVALUE      (TSC2005_CFR2_MAVE_X    | \
                     TSC2005_CFR2_MAVE_Y    | \
                     TSC2005_CFR2_MAVE_Z    | \
                     TSC2005_CFR2_MEDIUM_15 | \
                     TSC2005_CFR2_AVG_7)

#define MAX_12BIT           0xfff
#define TSC2005_SPI_MAX_SPEED_HZ    10000000
#define TSC2005_PENUP_TIME_MS       40

struct tsc2005_spi_rd {
    struct spi_transfer spi_xfer;
    u32         spi_tx;
    u32         spi_rx;
};

struct tsc2005 {
    struct spi_device   *spi;

    struct spi_message      spi_read_msg;
    struct tsc2005_spi_rd   spi_x;
    struct tsc2005_spi_rd   spi_y;
    struct tsc2005_spi_rd   spi_z1;
    struct tsc2005_spi_rd   spi_z2;

    struct input_dev    *idev;
    char            phys[32];

    struct mutex        mutex;

    /* raw copy of previous x,y,z */
    int         in_x;
    int         in_y;
    int                     in_z1;
    int         in_z2;

    spinlock_t      lock;
    struct timer_list   penup_timer;

    unsigned int        esd_timeout;
    struct delayed_work esd_work;
    unsigned long       last_valid_interrupt;

    unsigned int        x_plate_ohm;

    bool            opened;
    bool            suspended;

    bool            pen_down;

    void            (*set_reset)(bool enable);
};

static int tsc2005_cmd(struct tsc2005 *ts, u8 cmd)
{
    u8 tx = TSC2005_CMD | TSC2005_CMD_12BIT | cmd;
    struct spi_transfer xfer = {
        .tx_buf     = &tx,
        .len        = 1,
        .bits_per_word  = 8,
    };
    struct spi_message msg;
    int error;

    spi_message_init(&msg);
    spi_message_add_tail(&xfer, &msg);

    error = spi_sync(ts->spi, &msg);
    if (error) {
        dev_err(&ts->spi->dev, "%s: failed, command: %x, error: %d\n",
            __func__, cmd, error);
        return error;
    }

    return 0;
}

static int tsc2005_write(struct tsc2005 *ts, u8 reg, u16 value)
{
    u32 tx = ((reg | TSC2005_REG_PND0) << 16) | value;
    struct spi_transfer xfer = {
        .tx_buf     = &tx,
        .len        = 4,
        .bits_per_word  = 24,
    };
    struct spi_message msg;
    int error;

    spi_message_init(&msg);
    spi_message_add_tail(&xfer, &msg);

    error = spi_sync(ts->spi, &msg);
    if (error) {
        dev_err(&ts->spi->dev,
            "%s: failed, register: %x, value: %x, error: %d\n",
            __func__, reg, value, error);
        return error;
    }

    return 0;
}

static void tsc2005_setup_read(struct tsc2005_spi_rd *rd, u8 reg, bool last)
{
    memset(rd, 0, sizeof(*rd));

    rd->spi_tx         = (reg | TSC2005_REG_READ) << 16;
    rd->spi_xfer.tx_buf    = &rd->spi_tx;
    rd->spi_xfer.rx_buf    = &rd->spi_rx;
    rd->spi_xfer.len       = 4;
    rd->spi_xfer.bits_per_word = 24;
    rd->spi_xfer.cs_change     = !last;
}

static int tsc2005_read(struct tsc2005 *ts, u8 reg, u16 *value)
{
    struct tsc2005_spi_rd spi_rd;
    struct spi_message msg;
    int error;

    tsc2005_setup_read(&spi_rd, reg, true);

    spi_message_init(&msg);
    spi_message_add_tail(&spi_rd.spi_xfer, &msg);

    error = spi_sync(ts->spi, &msg);
    if (error)
        return error;

    *value = spi_rd.spi_rx;
    return 0;
}

static void tsc2005_update_pen_state(struct tsc2005 *ts,
                     int x, int y, int pressure)
{
    if (pressure) {
        input_report_abs(ts->idev, ABS_X, x);
        input_report_abs(ts->idev, ABS_Y, y);
        input_report_abs(ts->idev, ABS_PRESSURE, pressure);
        if (!ts->pen_down) {
            input_report_key(ts->idev, BTN_TOUCH, !!pressure);
            ts->pen_down = true;
        }
    } else {
        input_report_abs(ts->idev, ABS_PRESSURE, 0);
        if (ts->pen_down) {
            input_report_key(ts->idev, BTN_TOUCH, 0);
            ts->pen_down = false;
        }
    }
    input_sync(ts->idev);
    dev_dbg(&ts->spi->dev, "point(%4d,%4d), pressure (%4d)\n", x, y,
        pressure);
}

static irqreturn_t tsc2005_irq_thread(int irq, void *_ts)
{
    struct tsc2005 *ts = _ts;
    unsigned long flags;
    unsigned int pressure;
    u32 x, y;
    u32 z1, z2;
    int error;

    /* read the coordinates */
    error = spi_sync(ts->spi, &ts->spi_read_msg);
    if (unlikely(error))
        goto out;

    x = ts->spi_x.spi_rx;
    y = ts->spi_y.spi_rx;
    z1 = ts->spi_z1.spi_rx;
    z2 = ts->spi_z2.spi_rx;

    /* validate position */
    if (unlikely(x > MAX_12BIT || y > MAX_12BIT))
        goto out;

    /* Skip reading if the pressure components are out of range */
    if (unlikely(z1 == 0 || z2 > MAX_12BIT || z1 >= z2))
        goto out;

       /*
    * Skip point if this is a pen down with the exact same values as
    * the value before pen-up - that implies SPI fed us stale data
    */
    if (!ts->pen_down &&
        ts->in_x == x && ts->in_y == y &&
        ts->in_z1 == z1 && ts->in_z2 == z2) {
        goto out;
    }

    /*
     * At this point we are happy we have a valid and useful reading.
     * Remember it for later comparisons. We may now begin downsampling.
     */
    ts->in_x = x;
    ts->in_y = y;
    ts->in_z1 = z1;
    ts->in_z2 = z2;

    /* Compute touch pressure resistance using equation #1 */
    pressure = x * (z2 - z1) / z1;
    pressure = pressure * ts->x_plate_ohm / 4096;
    if (unlikely(pressure > MAX_12BIT))
        goto out;

    spin_lock_irqsave(&ts->lock, flags);

    tsc2005_update_pen_state(ts, x, y, pressure);
    mod_timer(&ts->penup_timer,
          jiffies + msecs_to_jiffies(TSC2005_PENUP_TIME_MS));

    spin_unlock_irqrestore(&ts->lock, flags);

    ts->last_valid_interrupt = jiffies;
out:
    return IRQ_HANDLED;
}

static void tsc2005_penup_timer(unsigned long data)
{
    struct tsc2005 *ts = (struct tsc2005 *)data;
    unsigned long flags;

    spin_lock_irqsave(&ts->lock, flags);
    tsc2005_update_pen_state(ts, 0, 0, 0);
    spin_unlock_irqrestore(&ts->lock, flags);
}

static void tsc2005_start_scan(struct tsc2005 *ts)
{
    tsc2005_write(ts, TSC2005_REG_CFR0, TSC2005_CFR0_INITVALUE);
    tsc2005_write(ts, TSC2005_REG_CFR1, TSC2005_CFR1_INITVALUE);
    tsc2005_write(ts, TSC2005_REG_CFR2, TSC2005_CFR2_INITVALUE);
    tsc2005_cmd(ts, TSC2005_CMD_NORMAL);
}

static void tsc2005_stop_scan(struct tsc2005 *ts)
{
    tsc2005_cmd(ts, TSC2005_CMD_STOP);
}

/* must be called with ts->mutex held */
static void __tsc2005_disable(struct tsc2005 *ts)
{
    tsc2005_stop_scan(ts);

    disable_irq(ts->spi->irq);
    del_timer_sync(&ts->penup_timer);

    cancel_delayed_work_sync(&ts->esd_work);

    enable_irq(ts->spi->irq);
}

/* must be called with ts->mutex held */
static void __tsc2005_enable(struct tsc2005 *ts)
{
    tsc2005_start_scan(ts);

    if (ts->esd_timeout && ts->set_reset) {
        ts->last_valid_interrupt = jiffies;
        schedule_delayed_work(&ts->esd_work,
                round_jiffies_relative(
                    msecs_to_jiffies(ts->esd_timeout)));
    }

}

static ssize_t tsc2005_selftest_show(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
{
    struct spi_device *spi = to_spi_device(dev);
    struct tsc2005 *ts = spi_get_drvdata(spi);
    u16 temp_high;
    u16 temp_high_orig;
    u16 temp_high_test;
    bool success = true;
    int error;

    mutex_lock(&ts->mutex);

    /*
     * Test TSC2005 communications via temp high register.
     */
    __tsc2005_disable(ts);

    error = tsc2005_read(ts, TSC2005_REG_TEMP_HIGH, &temp_high_orig);
    if (error) {
        dev_warn(dev, "selftest failed: read error %d\n", error);
        success = false;
        goto out;
    }

    temp_high_test = (temp_high_orig - 1) & MAX_12BIT;

    error = tsc2005_write(ts, TSC2005_REG_TEMP_HIGH, temp_high_test);
    if (error) {
        dev_warn(dev, "selftest failed: write error %d\n", error);
        success = false;
        goto out;
    }

    error = tsc2005_read(ts, TSC2005_REG_TEMP_HIGH, &temp_high);
    if (error) {
        dev_warn(dev, "selftest failed: read error %d after write\n",
             error);
        success = false;
        goto out;
    }

    if (temp_high != temp_high_test) {
        dev_warn(dev, "selftest failed: %d != %d\n",
             temp_high, temp_high_test);
        success = false;
    }

    /* hardware reset */
    ts->set_reset(false);
    usleep_range(100, 500); /* only 10us required */
    ts->set_reset(true);

    if (!success)
        goto out;

    /* test that the reset really happened */
    error = tsc2005_read(ts, TSC2005_REG_TEMP_HIGH, &temp_high);
    if (error) {
        dev_warn(dev, "selftest failed: read error %d after reset\n",
             error);
        success = false;
        goto out;
    }

    if (temp_high != temp_high_orig) {
        dev_warn(dev, "selftest failed after reset: %d != %d\n",
             temp_high, temp_high_orig);
        success = false;
    }

out:
    __tsc2005_enable(ts);
    mutex_unlock(&ts->mutex);

    return sprintf(buf, "%d\n", success);
}

static DEVICE_ATTR(selftest, S_IRUGO, tsc2005_selftest_show, NULL);

static struct attribute *tsc2005_attrs[] = {
    &dev_attr_selftest.attr,
    NULL
};

static umode_t tsc2005_attr_is_visible(struct kobject *kobj,
                      struct attribute *attr, int n)
{
    struct device *dev = container_of(kobj, struct device, kobj);
    struct spi_device *spi = to_spi_device(dev);
    struct tsc2005 *ts = spi_get_drvdata(spi);
    umode_t mode = attr->mode;

    if (attr == &dev_attr_selftest.attr) {
        if (!ts->set_reset)
            mode = 0;
    }

    return mode;
}

static const struct attribute_group tsc2005_attr_group = {
    .is_visible = tsc2005_attr_is_visible,
    .attrs      = tsc2005_attrs,
};

static void tsc2005_esd_work(struct work_struct *work)
{
    struct tsc2005 *ts = container_of(work, struct tsc2005, esd_work.work);
    int error;
    u16 r;

    if (!mutex_trylock(&ts->mutex)) {
        /*
         * If the mutex is taken, it means that disable or enable is in
         * progress. In that case just reschedule the work. If the work
         * is not needed, it will be canceled by disable.
         */
        goto reschedule;
    }

    if (time_is_after_jiffies(ts->last_valid_interrupt +
                  msecs_to_jiffies(ts->esd_timeout)))
        goto out;

    /* We should be able to read register without disabling interrupts. */
    error = tsc2005_read(ts, TSC2005_REG_CFR0, &r);
    if (!error &&
        !((r ^ TSC2005_CFR0_INITVALUE) & TSC2005_CFR0_RW_MASK)) {
        goto out;
    }

    /*
     * If we could not read our known value from configuration register 0
     * then we should reset the controller as if from power-up and start
     * scanning again.
     */
    dev_info(&ts->spi->dev, "TSC2005 not responding - resetting\n");

    disable_irq(ts->spi->irq);
    del_timer_sync(&ts->penup_timer);

    tsc2005_update_pen_state(ts, 0, 0, 0);

    ts->set_reset(false);
    usleep_range(100, 500); /* only 10us required */
    ts->set_reset(true);

    enable_irq(ts->spi->irq);
    tsc2005_start_scan(ts);

out:
    mutex_unlock(&ts->mutex);
reschedule:
    /* re-arm the watchdog */
    schedule_delayed_work(&ts->esd_work,
                  round_jiffies_relative(
                    msecs_to_jiffies(ts->esd_timeout)));
}

static int tsc2005_open(struct input_dev *input)
{
    struct tsc2005 *ts = input_get_drvdata(input);

    mutex_lock(&ts->mutex);

    if (!ts->suspended)
        __tsc2005_enable(ts);

    ts->opened = true;

    mutex_unlock(&ts->mutex);

    return 0;
}

static void tsc2005_close(struct input_dev *input)
{
    struct tsc2005 *ts = input_get_drvdata(input);

    mutex_lock(&ts->mutex);

    if (!ts->suspended)
        __tsc2005_disable(ts);

    ts->opened = false;

    mutex_unlock(&ts->mutex);
}

static void __devinit tsc2005_setup_spi_xfer(struct tsc2005 *ts)
{
    tsc2005_setup_read(&ts->spi_x, TSC2005_REG_X, false);
    tsc2005_setup_read(&ts->spi_y, TSC2005_REG_Y, false);
    tsc2005_setup_read(&ts->spi_z1, TSC2005_REG_Z1, false);
    tsc2005_setup_read(&ts->spi_z2, TSC2005_REG_Z2, true);

    spi_message_init(&ts->spi_read_msg);
    spi_message_add_tail(&ts->spi_x.spi_xfer, &ts->spi_read_msg);
    spi_message_add_tail(&ts->spi_y.spi_xfer, &ts->spi_read_msg);
    spi_message_add_tail(&ts->spi_z1.spi_xfer, &ts->spi_read_msg);
    spi_message_add_tail(&ts->spi_z2.spi_xfer, &ts->spi_read_msg);
}

static int __devinit tsc2005_probe(struct spi_device *spi)
{
    const struct tsc2005_platform_data *pdata = spi->dev.platform_data;
    struct tsc2005 *ts;
    struct input_dev *input_dev;
    unsigned int max_x, max_y, max_p;
    unsigned int fudge_x, fudge_y, fudge_p;
    int error;

    if (!pdata) {
        dev_dbg(&spi->dev, "no platform data\n");
        return -ENODEV;
    }

    fudge_x = pdata->ts_x_fudge    ? : 4;
    fudge_y = pdata->ts_y_fudge    ? : 8;
    fudge_p = pdata->ts_pressure_fudge ? : 2;
    max_x   = pdata->ts_x_max      ? : MAX_12BIT;
    max_y   = pdata->ts_y_max      ? : MAX_12BIT;
    max_p   = pdata->ts_pressure_max   ? : MAX_12BIT;

    if (spi->irq <= 0) {
        dev_dbg(&spi->dev, "no irq\n");
        return -ENODEV;
    }

    spi->mode = SPI_MODE_0;
    spi->bits_per_word = 8;
    if (!spi->max_speed_hz)
        spi->max_speed_hz = TSC2005_SPI_MAX_SPEED_HZ;

    error = spi_setup(spi);
    if (error)
        return error;

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

    ts->spi = spi;
    ts->idev = input_dev;

    ts->x_plate_ohm = pdata->ts_x_plate_ohm ? : 280;
    ts->esd_timeout = pdata->esd_timeout_ms;
    ts->set_reset   = pdata->set_reset;

    mutex_init(&ts->mutex);

    spin_lock_init(&ts->lock);
    setup_timer(&ts->penup_timer, tsc2005_penup_timer, (unsigned long)ts);

    INIT_DELAYED_WORK(&ts->esd_work, tsc2005_esd_work);

    tsc2005_setup_spi_xfer(ts);

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

    input_dev->name = "TSC2005 touchscreen";
    input_dev->phys = ts->phys;
    input_dev->id.bustype = BUS_SPI;
    input_dev->dev.parent = &spi->dev;
    input_dev->evbit[0] = BIT(EV_ABS) | BIT(EV_KEY);
    input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

    input_set_abs_params(input_dev, ABS_X, 0, max_x, fudge_x, 0);
    input_set_abs_params(input_dev, ABS_Y, 0, max_y, fudge_y, 0);
    input_set_abs_params(input_dev, ABS_PRESSURE, 0, max_p, fudge_p, 0);

    input_dev->open = tsc2005_open;
    input_dev->close = tsc2005_close;

    input_set_drvdata(input_dev, ts);

    /* Ensure the touchscreen is off */
    tsc2005_stop_scan(ts);

    error = request_threaded_irq(spi->irq, NULL, tsc2005_irq_thread,
                     IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                     "tsc2005", ts);
    if (error) {
        dev_err(&spi->dev, "Failed to request irq, err: %d\n", error);
        goto err_free_mem;
    }

    spi_set_drvdata(spi, ts);
    error = sysfs_create_group(&spi->dev.kobj, &tsc2005_attr_group);
    if (error) {
        dev_err(&spi->dev,
            "Failed to create sysfs attributes, err: %d\n", error);
        goto err_clear_drvdata;
    }

    error = input_register_device(ts->idev);
    if (error) {
        dev_err(&spi->dev,
            "Failed to register input device, err: %d\n", error);
        goto err_remove_sysfs;
    }

    irq_set_irq_wake(spi->irq, 1);
    return 0;

err_remove_sysfs:
    sysfs_remove_group(&spi->dev.kobj, &tsc2005_attr_group);
err_clear_drvdata:
    spi_set_drvdata(spi, NULL);
    free_irq(spi->irq, ts);
err_free_mem:
    input_free_device(input_dev);
    kfree(ts);
    return error;
}

static int __devexit tsc2005_remove(struct spi_device *spi)
{
    struct tsc2005 *ts = spi_get_drvdata(spi);

    sysfs_remove_group(&ts->spi->dev.kobj, &tsc2005_attr_group);

    free_irq(ts->spi->irq, ts);
    input_unregister_device(ts->idev);
    kfree(ts);

    spi_set_drvdata(spi, NULL);
    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tsc2005_suspend(struct device *dev)
{
    struct spi_device *spi = to_spi_device(dev);
    struct tsc2005 *ts = spi_get_drvdata(spi);

    mutex_lock(&ts->mutex);

    if (!ts->suspended && ts->opened)
        __tsc2005_disable(ts);

    ts->suspended = true;

    mutex_unlock(&ts->mutex);

    return 0;
}

static int tsc2005_resume(struct device *dev)
{
    struct spi_device *spi = to_spi_device(dev);
    struct tsc2005 *ts = spi_get_drvdata(spi);

    mutex_lock(&ts->mutex);

    if (ts->suspended && ts->opened)
        __tsc2005_enable(ts);

    ts->suspended = false;

    mutex_unlock(&ts->mutex);

    return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(tsc2005_pm_ops, tsc2005_suspend, tsc2005_resume);

static struct spi_driver tsc2005_driver = {
    .driver = {
        .name   = "tsc2005",
        .owner  = THIS_MODULE,
        .pm = &tsc2005_pm_ops,
    },
    .probe  = tsc2005_probe,
    .remove = __devexit_p(tsc2005_remove),
};

module_spi_driver(tsc2005_driver);

MODULE_AUTHOR("Lauri Leukkunen <[email protected]>");
MODULE_DESCRIPTION("TSC2005 Touchscreen Driver");
MODULE_LICENSE("GPL");