drivers/input/touchscreen/cyttsp_spi.c

   1 /*
   2  * Source for:
   3  * Cypress TrueTouch(TM) Standard Product (TTSP) SPI touchscreen driver.
   4  * For use with Cypress Txx3xx parts.
   5  * Supported parts include:
   6  * CY8CTST341
   7  * CY8CTMA340
   8  *
   9  * Copyright (C) 2009, 2010, 2011 Cypress Semiconductor, Inc.
  10  * Copyright (C) 2012 Javier Martinez Canillas <javier@dowhile0.org>
  11  * Copyright (C) 2013 Cypress Semiconductor
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * version 2, and only version 2, as published by the
  16  * Free Software Foundation.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * Contact Cypress Semiconductor at www.cypress.com <ttdrivers@cypress.com>
  24  *
  25  */
  26
  27 #include "cyttsp_core.h"
  28
  29 #include <linux/delay.h>
  30 #include <linux/input.h>
  31 #include <linux/spi/spi.h>
  32
  33 #define CY_SPI_WR_OP            0x00 /* r/~w */
  34 #define CY_SPI_RD_OP            0x01
  35 #define CY_SPI_CMD_BYTES        4
  36 #define CY_SPI_SYNC_BYTE        2
  37 #define CY_SPI_SYNC_ACK1        0x62 /* from protocol v.2 */
  38 #define CY_SPI_SYNC_ACK2        0x9D /* from protocol v.2 */
  39 #define CY_SPI_DATA_SIZE        128
  40 #define CY_SPI_DATA_BUF_SIZE    (CY_SPI_CMD_BYTES + CY_SPI_DATA_SIZE)
  41 #define CY_SPI_BITS_PER_WORD    8
  42
  43 static int cyttsp_spi_xfer(struct device *dev, u8 *xfer_buf,
  44                            u8 op, u16 reg, u8 *buf, int length)
  45 {
  46         struct spi_device *spi = to_spi_device(dev);
  47         struct spi_message msg;
  48         struct spi_transfer xfer[2];
  49         u8 *wr_buf = &xfer_buf[0];
  50         u8 *rd_buf = &xfer_buf[CY_SPI_DATA_BUF_SIZE];
  51         int retval;
  52         int i;
  53
  54         if (length > CY_SPI_DATA_SIZE) {
  55                 dev_err(dev, "%s: length %d is too big.\n",
  56                         __func__, length);
  57                 return -EINVAL;
  58         }
  59
  60         memset(wr_buf, 0, CY_SPI_DATA_BUF_SIZE);
  61         memset(rd_buf, 0, CY_SPI_DATA_BUF_SIZE);
  62
  63         wr_buf[0] = 0x00; /* header byte 0 */
  64         wr_buf[1] = 0xFF; /* header byte 1 */
  65         wr_buf[2] = reg;  /* reg index */
  66         wr_buf[3] = op;   /* r/~w */
  67         if (op == CY_SPI_WR_OP)
  68                 memcpy(wr_buf + CY_SPI_CMD_BYTES, buf, length);
  69
  70         memset(xfer, 0, sizeof(xfer));
  71         spi_message_init(&msg);
  72
  73         /*
  74           We set both TX and RX buffers because Cypress TTSP
  75           requires full duplex operation.
  76         */
  77         xfer[0].tx_buf = wr_buf;
  78         xfer[0].rx_buf = rd_buf;
  79         switch (op) {
  80         case CY_SPI_WR_OP:
  81                 xfer[0].len = length + CY_SPI_CMD_BYTES;
  82                 spi_message_add_tail(&xfer[0], &msg);
  83                 break;
  84
  85         case CY_SPI_RD_OP:
  86                 xfer[0].len = CY_SPI_CMD_BYTES;
  87                 spi_message_add_tail(&xfer[0], &msg);
  88
  89                 xfer[1].rx_buf = buf;
  90                 xfer[1].len = length;
  91                 spi_message_add_tail(&xfer[1], &msg);
  92                 break;
  93
  94         default:
  95                 dev_err(dev, "%s: bad operation code=%d\n", __func__, op);
  96                 return -EINVAL;
  97         }
  98
  99         retval = spi_sync(spi, &msg);
 100         if (retval < 0) {
 101                 dev_dbg(dev, "%s: spi_sync() error %d, len=%d, op=%d\n",
 102                         __func__, retval, xfer[1].len, op);
 103
 104                 /*
 105                  * do not return here since was a bad ACK sequence
 106                  * let the following ACK check handle any errors and
 107                  * allow silent retries
 108                  */
 109         }
 110
 111         if (rd_buf[CY_SPI_SYNC_BYTE] != CY_SPI_SYNC_ACK1 ||
 112             rd_buf[CY_SPI_SYNC_BYTE + 1] != CY_SPI_SYNC_ACK2) {
 113                 dev_dbg(dev, "%s: operation %d failed\n", __func__, op);
 114
 115                 for (i = 0; i < CY_SPI_CMD_BYTES; i++)
 116                         dev_dbg(dev, "%s: test rd_buf[%d]:0x%02x\n",
 117                                 __func__, i, rd_buf[i]);
 118                 for (i = 0; i < length; i++)
 119                         dev_dbg(dev, "%s: test buf[%d]:0x%02x\n",
 120                                 __func__, i, buf[i]);
 121
 122                 return -EIO;
 123         }
 124
 125         return 0;
 126 }
 127
 128 static int cyttsp_spi_read_block_data(struct device *dev, u8 *xfer_buf,
 129                                       u16 addr, u8 length, void *data)
 130 {
 131         return cyttsp_spi_xfer(dev, xfer_buf, CY_SPI_RD_OP, addr, data,
 132                         length);
 133 }
 134
 135 static int cyttsp_spi_write_block_data(struct device *dev, u8 *xfer_buf,
 136                                        u16 addr, u8 length, const void *data)
 137 {
 138         return cyttsp_spi_xfer(dev, xfer_buf, CY_SPI_WR_OP, addr, (void *)data,
 139                         length);
 140 }
 141
 142 static const struct cyttsp_bus_ops cyttsp_spi_bus_ops = {
 143         .bustype        = BUS_SPI,
 144         .write          = cyttsp_spi_write_block_data,
 145         .read           = cyttsp_spi_read_block_data,
 146 };
 147
 148 static int cyttsp_spi_probe(struct spi_device *spi)
 149 {
 150         struct cyttsp *ts;
 151         int error;
 152
 153         /* Set up SPI*/
 154         spi->bits_per_word = CY_SPI_BITS_PER_WORD;
 155         spi->mode = SPI_MODE_0;
 156         error = spi_setup(spi);
 157         if (error < 0) {
 158                 dev_err(&spi->dev, "%s: SPI setup error %d\n",
 159                         __func__, error);
 160                 return error;
 161         }
 162
 163         ts = cyttsp_probe(&cyttsp_spi_bus_ops, &spi->dev, spi->irq,
 164                           CY_SPI_DATA_BUF_SIZE * 2);
 165         if (IS_ERR(ts))
 166                 return PTR_ERR(ts);
 167
 168         spi_set_drvdata(spi, ts);
 169
 170         return 0;
 171 }
 172
 173 static struct spi_driver cyttsp_spi_driver = {
 174         .driver = {
 175                 .name   = CY_SPI_NAME,
 176                 .pm     = &cyttsp_pm_ops,
 177         },
 178         .probe  = cyttsp_spi_probe,
 179 };
 180
 181 module_spi_driver(cyttsp_spi_driver);
 182
 183 MODULE_LICENSE("GPL");
 184 MODULE_DESCRIPTION("Cypress TrueTouch(R) Standard Product (TTSP) SPI driver");
 185 MODULE_AUTHOR("Cypress");
 186 MODULE_ALIAS("spi:cyttsp");