cyttsp_spi.c

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/*
 * Source for:
 * Cypress TrueTouch(TM) Standard Product (TTSP) SPI touchscreen driver.
 * For use with Cypress Txx3xx parts.
 * Supported parts include:
 * CY8CTST341
 * CY8CTMA340
 *
 * Copyright (C) 2009, 2010, 2011 Cypress Semiconductor, Inc.
 * Copyright (C) 2012 Javier Martinez Canillas <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2, and only version 2, as published by the
 * Free Software Foundation.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Contact Cypress Semiconductor at www.cypress.com <[email protected]>
 *
 */

#include "cyttsp_core.h"

#include <linux/delay.h>
#include <linux/input.h>
#include <linux/spi/spi.h>

#define CY_SPI_WR_OP        0x00 /* r/~w */
#define CY_SPI_RD_OP        0x01
#define CY_SPI_CMD_BYTES    4
#define CY_SPI_SYNC_BYTE    2
#define CY_SPI_SYNC_ACK1    0x62 /* from protocol v.2 */
#define CY_SPI_SYNC_ACK2    0x9D /* from protocol v.2 */
#define CY_SPI_DATA_SIZE    128
#define CY_SPI_DATA_BUF_SIZE    (CY_SPI_CMD_BYTES + CY_SPI_DATA_SIZE)
#define CY_SPI_BITS_PER_WORD    8

static int cyttsp_spi_xfer(struct cyttsp *ts,
               u8 op, u8 reg, u8 *buf, int length)
{
    struct spi_device *spi = to_spi_device(ts->dev);
    struct spi_message msg;
    struct spi_transfer xfer[2];
    u8 *wr_buf = &ts->xfer_buf[0];
    u8 *rd_buf = &ts->xfer_buf[CY_SPI_DATA_BUF_SIZE];
    int retval;
    int i;

    if (length > CY_SPI_DATA_SIZE) {
        dev_err(ts->dev, "%s: length %d is too big.\n",
            __func__, length);
        return -EINVAL;
    }

    memset(wr_buf, 0, CY_SPI_DATA_BUF_SIZE);
    memset(rd_buf, 0, CY_SPI_DATA_BUF_SIZE);

    wr_buf[0] = 0x00; /* header byte 0 */
    wr_buf[1] = 0xFF; /* header byte 1 */
    wr_buf[2] = reg;  /* reg index */
    wr_buf[3] = op;   /* r/~w */
    if (op == CY_SPI_WR_OP)
        memcpy(wr_buf + CY_SPI_CMD_BYTES, buf, length);

    memset(xfer, 0, sizeof(xfer));
    spi_message_init(&msg);

    /*
      We set both TX and RX buffers because Cypress TTSP
      requires full duplex operation.
    */
    xfer[0].tx_buf = wr_buf;
    xfer[0].rx_buf = rd_buf;
    switch (op) {
    case CY_SPI_WR_OP:
        xfer[0].len = length + CY_SPI_CMD_BYTES;
        spi_message_add_tail(&xfer[0], &msg);
        break;

    case CY_SPI_RD_OP:
        xfer[0].len = CY_SPI_CMD_BYTES;
        spi_message_add_tail(&xfer[0], &msg);

        xfer[1].rx_buf = buf;
        xfer[1].len = length;
        spi_message_add_tail(&xfer[1], &msg);
        break;

    default:
        dev_err(ts->dev, "%s: bad operation code=%d\n", __func__, op);
        return -EINVAL;
    }

    retval = spi_sync(spi, &msg);
    if (retval < 0) {
        dev_dbg(ts->dev, "%s: spi_sync() error %d, len=%d, op=%d\n",
            __func__, retval, xfer[1].len, op);

        /*
         * do not return here since was a bad ACK sequence
         * let the following ACK check handle any errors and
         * allow silent retries
         */
    }

    if (rd_buf[CY_SPI_SYNC_BYTE] != CY_SPI_SYNC_ACK1 ||
        rd_buf[CY_SPI_SYNC_BYTE + 1] != CY_SPI_SYNC_ACK2) {

        dev_dbg(ts->dev, "%s: operation %d failed\n", __func__, op);

        for (i = 0; i < CY_SPI_CMD_BYTES; i++)
            dev_dbg(ts->dev, "%s: test rd_buf[%d]:0x%02x\n",
                __func__, i, rd_buf[i]);
        for (i = 0; i < length; i++)
            dev_dbg(ts->dev, "%s: test buf[%d]:0x%02x\n",
                __func__, i, buf[i]);

        return -EIO;
    }

    return 0;
}

static int cyttsp_spi_read_block_data(struct cyttsp *ts,
                      u8 addr, u8 length, void *data)
{
    return cyttsp_spi_xfer(ts, CY_SPI_RD_OP, addr, data, length);
}

static int cyttsp_spi_write_block_data(struct cyttsp *ts,
                       u8 addr, u8 length, const void *data)
{
    return cyttsp_spi_xfer(ts, CY_SPI_WR_OP, addr, (void *)data, length);
}

static const struct cyttsp_bus_ops cyttsp_spi_bus_ops = {
    .bustype    = BUS_SPI,
    .write      = cyttsp_spi_write_block_data,
    .read       = cyttsp_spi_read_block_data,
};

static int __devinit cyttsp_spi_probe(struct spi_device *spi)
{
    struct cyttsp *ts;
    int error;

    /* Set up SPI*/
    spi->bits_per_word = CY_SPI_BITS_PER_WORD;
    spi->mode = SPI_MODE_0;
    error = spi_setup(spi);
    if (error < 0) {
        dev_err(&spi->dev, "%s: SPI setup error %d\n",
            __func__, error);
        return error;
    }

    ts = cyttsp_probe(&cyttsp_spi_bus_ops, &spi->dev, spi->irq,
              CY_SPI_DATA_BUF_SIZE * 2);
    if (IS_ERR(ts))
        return PTR_ERR(ts);

    spi_set_drvdata(spi, ts);

    return 0;
}

static int __devexit cyttsp_spi_remove(struct spi_device *spi)
{
    struct cyttsp *ts = spi_get_drvdata(spi);

    cyttsp_remove(ts);

    return 0;
}

static struct spi_driver cyttsp_spi_driver = {
    .driver = {
        .name   = CY_SPI_NAME,
        .owner  = THIS_MODULE,
        .pm = &cyttsp_pm_ops,
    },
    .probe  = cyttsp_spi_probe,
    .remove = __devexit_p(cyttsp_spi_remove),
};

module_spi_driver(cyttsp_spi_driver);

MODULE_ALIAS("spi:cyttsp");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Cypress TrueTouch(R) Standard Product (TTSP) SPI driver");
MODULE_AUTHOR("Cypress");
MODULE_ALIAS("spi:cyttsp");