drivers/input/touchscreen/cyttsp_spi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Source for:
   4  * Cypress TrueTouch(TM) Standard Product (TTSP) SPI touchscreen driver.
   5  * For use with Cypress Txx3xx parts.
   6  * Supported parts include:
   7  * CY8CTST341
   8  * CY8CTMA340
   9  *
  10  * Copyright (C) 2009, 2010, 2011 Cypress Semiconductor, Inc.
  11  * Copyright (C) 2012 Javier Martinez Canillas <javier@dowhile0.org>
  12  * Copyright (C) 2013 Cypress Semiconductor
  13  *
  14  * Contact Cypress Semiconductor at www.cypress.com <ttdrivers@cypress.com>
  15  */
  16
  17 #include "cyttsp_core.h"
  18
  19 #include <linux/delay.h>
  20 #include <linux/input.h>
  21 #include <linux/spi/spi.h>
  22
  23 #define CY_SPI_WR_OP            0x00 /* r/~w */
  24 #define CY_SPI_RD_OP            0x01
  25 #define CY_SPI_CMD_BYTES        4
  26 #define CY_SPI_SYNC_BYTE        2
  27 #define CY_SPI_SYNC_ACK1        0x62 /* from protocol v.2 */
  28 #define CY_SPI_SYNC_ACK2        0x9D /* from protocol v.2 */
  29 #define CY_SPI_DATA_SIZE        128
  30 #define CY_SPI_DATA_BUF_SIZE    (CY_SPI_CMD_BYTES + CY_SPI_DATA_SIZE)
  31 #define CY_SPI_BITS_PER_WORD    8
  32
  33 static int cyttsp_spi_xfer(struct device *dev, u8 *xfer_buf,
  34                            u8 op, u16 reg, u8 *buf, int length)
  35 {
  36         struct spi_device *spi = to_spi_device(dev);
  37         struct spi_message msg;
  38         struct spi_transfer xfer[2];
  39         u8 *wr_buf = &xfer_buf[0];
  40         u8 *rd_buf = &xfer_buf[CY_SPI_DATA_BUF_SIZE];
  41         int retval;
  42         int i;
  43
  44         if (length > CY_SPI_DATA_SIZE) {
  45                 dev_err(dev, "%s: length %d is too big.\n",
  46                         __func__, length);
  47                 return -EINVAL;
  48         }
  49
  50         memset(wr_buf, 0, CY_SPI_DATA_BUF_SIZE);
  51         memset(rd_buf, 0, CY_SPI_DATA_BUF_SIZE);
  52
  53         wr_buf[0] = 0x00; /* header byte 0 */
  54         wr_buf[1] = 0xFF; /* header byte 1 */
  55         wr_buf[2] = reg;  /* reg index */
  56         wr_buf[3] = op;   /* r/~w */
  57         if (op == CY_SPI_WR_OP)
  58                 memcpy(wr_buf + CY_SPI_CMD_BYTES, buf, length);
  59
  60         memset(xfer, 0, sizeof(xfer));
  61         spi_message_init(&msg);
  62
  63         /*
  64           We set both TX and RX buffers because Cypress TTSP
  65           requires full duplex operation.
  66         */
  67         xfer[0].tx_buf = wr_buf;
  68         xfer[0].rx_buf = rd_buf;
  69         switch (op) {
  70         case CY_SPI_WR_OP:
  71                 xfer[0].len = length + CY_SPI_CMD_BYTES;
  72                 spi_message_add_tail(&xfer[0], &msg);
  73                 break;
  74
  75         case CY_SPI_RD_OP:
  76                 xfer[0].len = CY_SPI_CMD_BYTES;
  77                 spi_message_add_tail(&xfer[0], &msg);
  78
  79                 xfer[1].rx_buf = buf;
  80                 xfer[1].len = length;
  81                 spi_message_add_tail(&xfer[1], &msg);
  82                 break;
  83
  84         default:
  85                 dev_err(dev, "%s: bad operation code=%d\n", __func__, op);
  86                 return -EINVAL;
  87         }
  88
  89         retval = spi_sync(spi, &msg);
  90         if (retval < 0) {
  91                 dev_dbg(dev, "%s: spi_sync() error %d, len=%d, op=%d\n",
  92                         __func__, retval, xfer[1].len, op);
  93
  94                 /*
  95                  * do not return here since was a bad ACK sequence
  96                  * let the following ACK check handle any errors and
  97                  * allow silent retries
  98                  */
  99         }
 100
 101         if (rd_buf[CY_SPI_SYNC_BYTE] != CY_SPI_SYNC_ACK1 ||
 102             rd_buf[CY_SPI_SYNC_BYTE + 1] != CY_SPI_SYNC_ACK2) {
 103                 dev_dbg(dev, "%s: operation %d failed\n", __func__, op);
 104
 105                 for (i = 0; i < CY_SPI_CMD_BYTES; i++)
 106                         dev_dbg(dev, "%s: test rd_buf[%d]:0x%02x\n",
 107                                 __func__, i, rd_buf[i]);
 108                 for (i = 0; i < length; i++)
 109                         dev_dbg(dev, "%s: test buf[%d]:0x%02x\n",
 110                                 __func__, i, buf[i]);
 111
 112                 return -EIO;
 113         }
 114
 115         return 0;
 116 }
 117
 118 static int cyttsp_spi_read_block_data(struct device *dev, u8 *xfer_buf,
 119                                       u16 addr, u8 length, void *data)
 120 {
 121         return cyttsp_spi_xfer(dev, xfer_buf, CY_SPI_RD_OP, addr, data,
 122                         length);
 123 }
 124
 125 static int cyttsp_spi_write_block_data(struct device *dev, u8 *xfer_buf,
 126                                        u16 addr, u8 length, const void *data)
 127 {
 128         return cyttsp_spi_xfer(dev, xfer_buf, CY_SPI_WR_OP, addr, (void *)data,
 129                         length);
 130 }
 131
 132 static const struct cyttsp_bus_ops cyttsp_spi_bus_ops = {
 133         .bustype        = BUS_SPI,
 134         .write          = cyttsp_spi_write_block_data,
 135         .read           = cyttsp_spi_read_block_data,
 136 };
 137
 138 static int cyttsp_spi_probe(struct spi_device *spi)
 139 {
 140         struct cyttsp *ts;
 141         int error;
 142
 143         /* Set up SPI*/
 144         spi->bits_per_word = CY_SPI_BITS_PER_WORD;
 145         spi->mode = SPI_MODE_0;
 146         error = spi_setup(spi);
 147         if (error < 0) {
 148                 dev_err(&spi->dev, "%s: SPI setup error %d\n",
 149                         __func__, error);
 150                 return error;
 151         }
 152
 153         ts = cyttsp_probe(&cyttsp_spi_bus_ops, &spi->dev, spi->irq,
 154                           CY_SPI_DATA_BUF_SIZE * 2);
 155         if (IS_ERR(ts))
 156                 return PTR_ERR(ts);
 157
 158         spi_set_drvdata(spi, ts);
 159
 160         return 0;
 161 }
 162
 163 static struct spi_driver cyttsp_spi_driver = {
 164         .driver = {
 165                 .name   = CY_SPI_NAME,
 166                 .pm     = &cyttsp_pm_ops,
 167         },
 168         .probe  = cyttsp_spi_probe,
 169 };
 170
 171 module_spi_driver(cyttsp_spi_driver);
 172
 173 MODULE_LICENSE("GPL");
 174 MODULE_DESCRIPTION("Cypress TrueTouch(R) Standard Product (TTSP) SPI driver");
 175 MODULE_AUTHOR("Cypress");
 176 MODULE_ALIAS("spi:cyttsp");