intel-mid-touch.c

Go to the documentation of this file.

/*
 * Intel MID Resistive Touch Screen Driver
 *
 * Copyright (C) 2008 Intel Corp
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * 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; version 2 of the License.
 *
 * 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.
 *
 * Questions/Comments/Bug fixes to Sreedhara ([email protected])
 *              Ramesh Agarwal ([email protected])
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * TODO:
 *  review conversion of r/m/w sequences
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/param.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <asm/intel_scu_ipc.h>

/* PMIC Interrupt registers */
#define PMIC_REG_ID1        0x00 /* PMIC ID1 register */

/* PMIC Interrupt registers */
#define PMIC_REG_INT        0x04 /* PMIC interrupt register */
#define PMIC_REG_MINT       0x05 /* PMIC interrupt mask register */

/* ADC Interrupt registers */
#define PMIC_REG_ADCINT     0x5F /* ADC interrupt register */
#define PMIC_REG_MADCINT    0x60 /* ADC interrupt mask register */

/* ADC Control registers */
#define PMIC_REG_ADCCNTL1   0x61 /* ADC control register */

/* ADC Channel Selection registers */
#define PMICADDR0       0xA4
#define END_OF_CHANNEL      0x1F

/* ADC Result register */
#define PMIC_REG_ADCSNS0H   0x64

/* ADC channels for touch screen */
#define MRST_TS_CHAN10      0xA /* Touch screen X+ connection */
#define MRST_TS_CHAN11      0xB /* Touch screen X- connection */
#define MRST_TS_CHAN12      0xC /* Touch screen Y+ connection */
#define MRST_TS_CHAN13      0xD /* Touch screen Y- connection */

/* Touch screen channel BIAS constants */
#define MRST_XBIAS      0x20
#define MRST_YBIAS      0x40
#define MRST_ZBIAS      0x80

/* Touch screen coordinates */
#define MRST_X_MIN      10
#define MRST_X_MAX      1024
#define MRST_X_FUZZ     5
#define MRST_Y_MIN      10
#define MRST_Y_MAX      1024
#define MRST_Y_FUZZ     5
#define MRST_PRESSURE_MIN   0
#define MRST_PRESSURE_NOMINAL   50
#define MRST_PRESSURE_MAX   100

#define WAIT_ADC_COMPLETION 10 /* msec */

/* PMIC ADC round robin delays */
#define ADC_LOOP_DELAY0     0x0 /* Continuous loop */
#define ADC_LOOP_DELAY1     0x1 /* 4.5  ms approximate */

/* PMIC Vendor Identifiers */
#define PMIC_VENDOR_FS      0 /* PMIC vendor FreeScale */
#define PMIC_VENDOR_MAXIM   1 /* PMIC vendor MAXIM */
#define PMIC_VENDOR_NEC     2 /* PMIC vendor NEC */
#define MRSTOUCH_MAX_CHANNELS   32 /* Maximum ADC channels */

/* Touch screen device structure */
struct mrstouch_dev {
    struct device *dev; /* device associated with touch screen */
    struct input_dev *input;
    char phys[32];
    u16 asr;        /* Address selection register */
    int irq;
    unsigned int vendor;    /* PMIC vendor */
    unsigned int rev;   /* PMIC revision */

    int (*read_prepare)(struct mrstouch_dev *tsdev);
    int (*read)(struct mrstouch_dev *tsdev, u16 *x, u16 *y, u16 *z);
    int (*read_finish)(struct mrstouch_dev *tsdev);
};


/*************************** NEC and Maxim Interface ************************/

static int mrstouch_nec_adc_read_prepare(struct mrstouch_dev *tsdev)
{
    return intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0, 0x20);
}

/*
 * Enables PENDET interrupt.
 */
static int mrstouch_nec_adc_read_finish(struct mrstouch_dev *tsdev)
{
    int err;

    err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x20, 0x20);
    if (!err)
        err = intel_scu_ipc_update_register(PMIC_REG_ADCCNTL1, 0, 0x05);

    return err;
}

/*
 * Reads PMIC ADC touch screen result
 * Reads ADC storage registers for higher 7 and lower 3 bits and
 * converts the two readings into a single value and turns off gain bit
 */
static int mrstouch_ts_chan_read(u16 offset, u16 chan, u16 *vp, u16 *vm)
{
    int err;
    u16 result;
    u32 res;

    result = PMIC_REG_ADCSNS0H + offset;

    if (chan == MRST_TS_CHAN12)
        result += 4;

    err = intel_scu_ipc_ioread32(result, &res);
    if (err)
        return err;

    /* Mash the bits up */

    *vp = (res & 0xFF) << 3;    /* Highest 7 bits */
    *vp |= (res >> 8) & 0x07;   /* Lower 3 bits */
    *vp &= 0x3FF;

    res >>= 16;

    *vm = (res & 0xFF) << 3;    /* Highest 7 bits */
    *vm |= (res >> 8) & 0x07;   /* Lower 3 bits */
    *vm &= 0x3FF;

    return 0;
}

/*
 * Enables X, Y and Z bias values
 * Enables YPYM for X channels and XPXM for Y channels
 */
static int mrstouch_ts_bias_set(uint offset, uint bias)
{
    int count;
    u16 chan, start;
    u16 reg[4];
    u8 data[4];

    chan = PMICADDR0 + offset;
    start = MRST_TS_CHAN10;

    for (count = 0; count <= 3; count++) {
        reg[count] = chan++;
        data[count] = bias | (start + count);
    }

    return intel_scu_ipc_writev(reg, data, 4);
}

/* To read touch screen channel values */
static int mrstouch_nec_adc_read(struct mrstouch_dev *tsdev,
                 u16 *x, u16 *y, u16 *z)
{
    int err;
    u16 xm, ym, zm;

    /* configure Y bias for X channels */
    err = mrstouch_ts_bias_set(tsdev->asr, MRST_YBIAS);
    if (err)
        goto ipc_error;

    msleep(WAIT_ADC_COMPLETION);

    /* read x+ and x- channels */
    err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN10, x, &xm);
    if (err)
        goto ipc_error;

    /* configure x bias for y channels */
    err = mrstouch_ts_bias_set(tsdev->asr, MRST_XBIAS);
    if (err)
        goto ipc_error;

    msleep(WAIT_ADC_COMPLETION);

    /* read y+ and y- channels */
    err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN12, y, &ym);
    if (err)
        goto ipc_error;

    /* configure z bias for x and y channels */
    err = mrstouch_ts_bias_set(tsdev->asr, MRST_ZBIAS);
    if (err)
        goto ipc_error;

    msleep(WAIT_ADC_COMPLETION);

    /* read z+ and z- channels */
    err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN10, z, &zm);
    if (err)
        goto ipc_error;

    return 0;

ipc_error:
    dev_err(tsdev->dev, "ipc error during adc read\n");
    return err;
}


/*************************** Freescale Interface ************************/

static int mrstouch_fs_adc_read_prepare(struct mrstouch_dev *tsdev)
{
    int err, count;
    u16 chan;
    u16 reg[5];
    u8 data[5];

    /* Stop the ADC */
    err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x00, 0x02);
    if (err)
        goto ipc_error;

    chan = PMICADDR0 + tsdev->asr;

    /* Set X BIAS */
    for (count = 0; count <= 3; count++) {
        reg[count] = chan++;
        data[count] = 0x2A;
    }
    reg[count] =  chan++; /* Dummy */
    data[count] = 0;

    err = intel_scu_ipc_writev(reg, data, 5);
    if (err)
        goto ipc_error;

    msleep(WAIT_ADC_COMPLETION);

    /* Set Y BIAS */
    for (count = 0; count <= 3; count++) {
        reg[count] = chan++;
        data[count] = 0x4A;
    }
    reg[count] = chan++; /* Dummy */
    data[count] = 0;

    err = intel_scu_ipc_writev(reg, data, 5);
    if (err)
        goto ipc_error;

    msleep(WAIT_ADC_COMPLETION);

    /* Set Z BIAS */
    err = intel_scu_ipc_iowrite32(chan + 2, 0x8A8A8A8A);
    if (err)
        goto ipc_error;

    msleep(WAIT_ADC_COMPLETION);

    return 0;

ipc_error:
    dev_err(tsdev->dev, "ipc error during %s\n", __func__);
    return err;
}

static int mrstouch_fs_adc_read(struct mrstouch_dev *tsdev,
                u16 *x, u16 *y, u16 *z)
{
    int err;
    u16 result;
    u16 reg[4];
    u8 data[4];

    result = PMIC_REG_ADCSNS0H + tsdev->asr;

    reg[0] = result + 4;
    reg[1] = result + 5;
    reg[2] = result + 16;
    reg[3] = result + 17;

    err = intel_scu_ipc_readv(reg, data, 4);
    if (err)
        goto ipc_error;

    *x = data[0] << 3; /* Higher 7 bits */
    *x |= data[1] & 0x7; /* Lower 3 bits */
    *x &= 0x3FF;

    *y = data[2] << 3; /* Higher 7 bits */
    *y |= data[3] & 0x7; /* Lower 3 bits */
    *y &= 0x3FF;

    /* Read Z value */
    reg[0] = result + 28;
    reg[1] = result + 29;

    err = intel_scu_ipc_readv(reg, data, 4);
    if (err)
        goto ipc_error;

    *z = data[0] << 3; /* Higher 7 bits */
    *z |= data[1] & 0x7; /* Lower 3 bits */
    *z &= 0x3FF;

    return 0;

ipc_error:
    dev_err(tsdev->dev, "ipc error during %s\n", __func__);
    return err;
}

static int mrstouch_fs_adc_read_finish(struct mrstouch_dev *tsdev)
{
    int err, count;
    u16 chan;
    u16 reg[5];
    u8 data[5];

    /* Clear all TS channels */
    chan = PMICADDR0 + tsdev->asr;
    for (count = 0; count <= 4; count++) {
        reg[count] = chan++;
        data[count] = 0;
    }
    err = intel_scu_ipc_writev(reg, data, 5);
    if (err)
        goto ipc_error;

    for (count = 0; count <= 4; count++) {
        reg[count] = chan++;
        data[count] = 0;
    }
    err = intel_scu_ipc_writev(reg, data, 5);
    if (err)
        goto ipc_error;

    err = intel_scu_ipc_iowrite32(chan + 2, 0x00000000);
    if (err)
        goto ipc_error;

    /* Start ADC */
    err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x02, 0x02);
    if (err)
        goto ipc_error;

    return 0;

ipc_error:
    dev_err(tsdev->dev, "ipc error during %s\n", __func__);
    return err;
}

static void mrstouch_report_event(struct input_dev *input,
            unsigned int x, unsigned int y, unsigned int z)
{
    if (z > MRST_PRESSURE_NOMINAL) {
        /* Pen touched, report button touch and coordinates */
        input_report_key(input, BTN_TOUCH, 1);
        input_report_abs(input, ABS_X, x);
        input_report_abs(input, ABS_Y, y);
    } else {
        input_report_key(input, BTN_TOUCH, 0);
    }

    input_report_abs(input, ABS_PRESSURE, z);
    input_sync(input);
}

/* PENDET interrupt handler */
static irqreturn_t mrstouch_pendet_irq(int irq, void *dev_id)
{
    struct mrstouch_dev *tsdev = dev_id;
    u16 x, y, z;

    /*
     * Should we lower thread priority? Probably not, since we are
     * not spinning but sleeping...
     */

    if (tsdev->read_prepare(tsdev))
        goto out;

    do {
        if (tsdev->read(tsdev, &x, &y, &z))
            break;

        mrstouch_report_event(tsdev->input, x, y, z);
    } while (z > MRST_PRESSURE_NOMINAL);

    tsdev->read_finish(tsdev);

out:
    return IRQ_HANDLED;
}

/* Utility to read PMIC ID */
static int __devinit mrstouch_read_pmic_id(uint *vendor, uint *rev)
{
    int err;
    u8 r;

    err = intel_scu_ipc_ioread8(PMIC_REG_ID1, &r);
    if (err)
        return err;

    *vendor = r & 0x7;
    *rev = (r >> 3) & 0x7;

    return 0;
}

/*
 * Parse ADC channels to find end of the channel configured by other ADC user
 * NEC and MAXIM requires 4 channels and FreeScale needs 18 channels
 */
static int __devinit mrstouch_chan_parse(struct mrstouch_dev *tsdev)
{
    int found = 0;
    int err, i;
    u8 r8;

    for (i = 0; i < MRSTOUCH_MAX_CHANNELS; i++) {
        err = intel_scu_ipc_ioread8(PMICADDR0 + i, &r8);
        if (err)
            return err;

        if (r8 == END_OF_CHANNEL) {
            found = i;
            break;
        }
    }

    if (tsdev->vendor == PMIC_VENDOR_FS) {
        if (found > MRSTOUCH_MAX_CHANNELS - 18)
            return -ENOSPC;
    } else {
        if (found > MRSTOUCH_MAX_CHANNELS - 4)
            return -ENOSPC;
    }

    return found;
}


/*
 * Writes touch screen channels to ADC address selection registers
 */
static int __devinit mrstouch_ts_chan_set(uint offset)
{
    u16 chan;

    int ret, count;

    chan = PMICADDR0 + offset;
    for (count = 0; count <= 3; count++) {
        ret = intel_scu_ipc_iowrite8(chan++, MRST_TS_CHAN10 + count);
        if (ret)
            return ret;
    }
    return intel_scu_ipc_iowrite8(chan++, END_OF_CHANNEL);
}

/* Initialize ADC */
static int __devinit mrstouch_adc_init(struct mrstouch_dev *tsdev)
{
    int err, start;
    u8 ra, rm;

    err = mrstouch_read_pmic_id(&tsdev->vendor, &tsdev->rev);
    if (err) {
        dev_err(tsdev->dev, "Unable to read PMIC id\n");
        return err;
    }

    switch (tsdev->vendor) {
    case PMIC_VENDOR_NEC:
    case PMIC_VENDOR_MAXIM:
        tsdev->read_prepare = mrstouch_nec_adc_read_prepare;
        tsdev->read = mrstouch_nec_adc_read;
        tsdev->read_finish = mrstouch_nec_adc_read_finish;
        break;

    case PMIC_VENDOR_FS:
        tsdev->read_prepare = mrstouch_fs_adc_read_prepare;
        tsdev->read = mrstouch_fs_adc_read;
        tsdev->read_finish = mrstouch_fs_adc_read_finish;
        break;

    default:
        dev_err(tsdev->dev,
            "Unsupported touchscreen: %d\n", tsdev->vendor);
        return -ENXIO;
    }

    start = mrstouch_chan_parse(tsdev);
    if (start < 0) {
        dev_err(tsdev->dev, "Unable to parse channels\n");
        return start;
    }

    tsdev->asr = start;

    /*
     * ADC power on, start, enable PENDET and set loop delay
     * ADC loop delay is set to 4.5 ms approximately
     * Loop delay more than this results in jitter in adc readings
     * Setting loop delay to 0 (continuous loop) in MAXIM stops PENDET
     * interrupt generation sometimes.
     */

    if (tsdev->vendor == PMIC_VENDOR_FS) {
        ra = 0xE0 | ADC_LOOP_DELAY0;
        rm = 0x5;
    } else {
        /* NEC and MAXIm not consistent with loop delay 0 */
        ra = 0xE0 | ADC_LOOP_DELAY1;
        rm = 0x0;

        /* configure touch screen channels */
        err = mrstouch_ts_chan_set(tsdev->asr);
        if (err)
            return err;
    }

    err = intel_scu_ipc_update_register(PMIC_REG_ADCCNTL1, ra, 0xE7);
    if (err)
        return err;

    err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, rm, 0x03);
    if (err)
        return err;

    return 0;
}


/* Probe function for touch screen driver */
static int __devinit mrstouch_probe(struct platform_device *pdev)
{
    struct mrstouch_dev *tsdev;
    struct input_dev *input;
    int err;
    int irq;

    irq = platform_get_irq(pdev, 0);
    if (irq < 0) {
        dev_err(&pdev->dev, "no interrupt assigned\n");
        return -EINVAL;
    }

    tsdev = kzalloc(sizeof(struct mrstouch_dev), GFP_KERNEL);
    input = input_allocate_device();
    if (!tsdev || !input) {
        dev_err(&pdev->dev, "unable to allocate memory\n");
        err = -ENOMEM;
        goto err_free_mem;
    }

    tsdev->dev = &pdev->dev;
    tsdev->input = input;
    tsdev->irq = irq;

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

    err = mrstouch_adc_init(tsdev);
    if (err) {
        dev_err(&pdev->dev, "ADC initialization failed\n");
        goto err_free_mem;
    }

    input->name = "mrst_touchscreen";
    input->phys = tsdev->phys;
    input->dev.parent = tsdev->dev;

    input->id.vendor = tsdev->vendor;
    input->id.version = tsdev->rev;

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

    input_set_abs_params(tsdev->input, ABS_X,
                 MRST_X_MIN, MRST_X_MAX, MRST_X_FUZZ, 0);
    input_set_abs_params(tsdev->input, ABS_Y,
                 MRST_Y_MIN, MRST_Y_MAX, MRST_Y_FUZZ, 0);
    input_set_abs_params(tsdev->input, ABS_PRESSURE,
                 MRST_PRESSURE_MIN, MRST_PRESSURE_MAX, 0, 0);

    err = request_threaded_irq(tsdev->irq, NULL, mrstouch_pendet_irq,
                   IRQF_ONESHOT, "mrstouch", tsdev);
    if (err) {
        dev_err(tsdev->dev, "unable to allocate irq\n");
        goto err_free_mem;
    }

    err = input_register_device(tsdev->input);
    if (err) {
        dev_err(tsdev->dev, "unable to register input device\n");
        goto err_free_irq;
    }

    platform_set_drvdata(pdev, tsdev);
    return 0;

err_free_irq:
    free_irq(tsdev->irq, tsdev);
err_free_mem:
    input_free_device(input);
    kfree(tsdev);
    return err;
}

static int __devexit mrstouch_remove(struct platform_device *pdev)
{
    struct mrstouch_dev *tsdev = platform_get_drvdata(pdev);

    free_irq(tsdev->irq, tsdev);
    input_unregister_device(tsdev->input);
    kfree(tsdev);

    platform_set_drvdata(pdev, NULL);

    return 0;
}

static struct platform_driver mrstouch_driver = {
    .driver = {
        .name   = "pmic_touch",
        .owner  = THIS_MODULE,
    },
    .probe      = mrstouch_probe,
    .remove     = __devexit_p(mrstouch_remove),
};
module_platform_driver(mrstouch_driver);

MODULE_AUTHOR("Sreedhara Murthy. D.S, [email protected]");
MODULE_DESCRIPTION("Intel Moorestown Resistive Touch Screen Driver");
MODULE_LICENSE("GPL");