input/touchscreen/cyttsp_spi.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Source for:
0004  * Cypress TrueTouch(TM) Standard Product (TTSP) SPI touchscreen driver.
0005  * For use with Cypress Txx3xx parts.
0006  * Supported parts include:
0007  * CY8CTST341
0008  * CY8CTMA340
0009  *
0010  * Copyright (C) 2009, 2010, 2011 Cypress Semiconductor, Inc.
0011  * Copyright (C) 2012 Javier Martinez Canillas <javier@dowhile0.org>
0012  * Copyright (C) 2013 Cypress Semiconductor
0013  *
0014  * Contact Cypress Semiconductor at www.cypress.com <ttdrivers@cypress.com>
0015  */
0016
0017 #include "cyttsp_core.h"
0018
0019 #include <linux/delay.h>
0020 #include <linux/input.h>
0021 #include <linux/spi/spi.h>
0022
0023 #define CY_SPI_NAME     "cyttsp-spi"
0024
0025 #define CY_SPI_WR_OP        0x00 /* r/~w */
0026 #define CY_SPI_RD_OP        0x01
0027 #define CY_SPI_CMD_BYTES    4
0028 #define CY_SPI_SYNC_BYTE    2
0029 #define CY_SPI_SYNC_ACK1    0x62 /* from protocol v.2 */
0030 #define CY_SPI_SYNC_ACK2    0x9D /* from protocol v.2 */
0031 #define CY_SPI_DATA_SIZE    128
0032 #define CY_SPI_DATA_BUF_SIZE    (CY_SPI_CMD_BYTES + CY_SPI_DATA_SIZE)
0033 #define CY_SPI_BITS_PER_WORD    8
0034
0035 static int cyttsp_spi_xfer(struct device *dev, u8 *xfer_buf,
0036                u8 op, u16 reg, u8 *buf, int length)
0037 {
0038     struct spi_device *spi = to_spi_device(dev);
0039     struct spi_message msg;
0040     struct spi_transfer xfer[2];
0041     u8 *wr_buf = &xfer_buf[0];
0042     u8 *rd_buf = &xfer_buf[CY_SPI_DATA_BUF_SIZE];
0043     int retval;
0044     int i;
0045
0046     if (length > CY_SPI_DATA_SIZE) {
0047         dev_err(dev, "%s: length %d is too big.\n",
0048             __func__, length);
0049         return -EINVAL;
0050     }
0051
0052     memset(wr_buf, 0, CY_SPI_DATA_BUF_SIZE);
0053     memset(rd_buf, 0, CY_SPI_DATA_BUF_SIZE);
0054
0055     wr_buf[0] = 0x00; /* header byte 0 */
0056     wr_buf[1] = 0xFF; /* header byte 1 */
0057     wr_buf[2] = reg;  /* reg index */
0058     wr_buf[3] = op;   /* r/~w */
0059     if (op == CY_SPI_WR_OP)
0060         memcpy(wr_buf + CY_SPI_CMD_BYTES, buf, length);
0061
0062     memset(xfer, 0, sizeof(xfer));
0063     spi_message_init(&msg);
0064
0065     /*
0066       We set both TX and RX buffers because Cypress TTSP
0067       requires full duplex operation.
0068     */
0069     xfer[0].tx_buf = wr_buf;
0070     xfer[0].rx_buf = rd_buf;
0071     switch (op) {
0072     case CY_SPI_WR_OP:
0073         xfer[0].len = length + CY_SPI_CMD_BYTES;
0074         spi_message_add_tail(&xfer[0], &msg);
0075         break;
0076
0077     case CY_SPI_RD_OP:
0078         xfer[0].len = CY_SPI_CMD_BYTES;
0079         spi_message_add_tail(&xfer[0], &msg);
0080
0081         xfer[1].rx_buf = buf;
0082         xfer[1].len = length;
0083         spi_message_add_tail(&xfer[1], &msg);
0084         break;
0085
0086     default:
0087         dev_err(dev, "%s: bad operation code=%d\n", __func__, op);
0088         return -EINVAL;
0089     }
0090
0091     retval = spi_sync(spi, &msg);
0092     if (retval < 0) {
0093         dev_dbg(dev, "%s: spi_sync() error %d, len=%d, op=%d\n",
0094             __func__, retval, xfer[1].len, op);
0095
0096         /*
0097          * do not return here since was a bad ACK sequence
0098          * let the following ACK check handle any errors and
0099          * allow silent retries
0100          */
0101     }
0102
0103     if (rd_buf[CY_SPI_SYNC_BYTE] != CY_SPI_SYNC_ACK1 ||
0104         rd_buf[CY_SPI_SYNC_BYTE + 1] != CY_SPI_SYNC_ACK2) {
0105         dev_dbg(dev, "%s: operation %d failed\n", __func__, op);
0106
0107         for (i = 0; i < CY_SPI_CMD_BYTES; i++)
0108             dev_dbg(dev, "%s: test rd_buf[%d]:0x%02x\n",
0109                 __func__, i, rd_buf[i]);
0110         for (i = 0; i < length; i++)
0111             dev_dbg(dev, "%s: test buf[%d]:0x%02x\n",
0112                 __func__, i, buf[i]);
0113
0114         return -EIO;
0115     }
0116
0117     return 0;
0118 }
0119
0120 static int cyttsp_spi_read_block_data(struct device *dev, u8 *xfer_buf,
0121                       u16 addr, u8 length, void *data)
0122 {
0123     return cyttsp_spi_xfer(dev, xfer_buf, CY_SPI_RD_OP, addr, data,
0124             length);
0125 }
0126
0127 static int cyttsp_spi_write_block_data(struct device *dev, u8 *xfer_buf,
0128                        u16 addr, u8 length, const void *data)
0129 {
0130     return cyttsp_spi_xfer(dev, xfer_buf, CY_SPI_WR_OP, addr, (void *)data,
0131             length);
0132 }
0133
0134 static const struct cyttsp_bus_ops cyttsp_spi_bus_ops = {
0135     .bustype    = BUS_SPI,
0136     .write      = cyttsp_spi_write_block_data,
0137     .read       = cyttsp_spi_read_block_data,
0138 };
0139
0140 static int cyttsp_spi_probe(struct spi_device *spi)
0141 {
0142     struct cyttsp *ts;
0143     int error;
0144
0145     /* Set up SPI*/
0146     spi->bits_per_word = CY_SPI_BITS_PER_WORD;
0147     spi->mode = SPI_MODE_0;
0148     error = spi_setup(spi);
0149     if (error < 0) {
0150         dev_err(&spi->dev, "%s: SPI setup error %d\n",
0151             __func__, error);
0152         return error;
0153     }
0154
0155     ts = cyttsp_probe(&cyttsp_spi_bus_ops, &spi->dev, spi->irq,
0156               CY_SPI_DATA_BUF_SIZE * 2);
0157     if (IS_ERR(ts))
0158         return PTR_ERR(ts);
0159
0160     spi_set_drvdata(spi, ts);
0161
0162     return 0;
0163 }
0164
0165 static const struct of_device_id cyttsp_of_spi_match[] = {
0166     { .compatible = "cypress,cy8ctma340", },
0167     { .compatible = "cypress,cy8ctst341", },
0168     { /* sentinel */ }
0169 };
0170 MODULE_DEVICE_TABLE(of, cyttsp_of_spi_match);
0171
0172 static struct spi_driver cyttsp_spi_driver = {
0173     .driver = {
0174         .name   = CY_SPI_NAME,
0175         .pm = &cyttsp_pm_ops,
0176         .of_match_table = cyttsp_of_spi_match,
0177     },
0178     .probe  = cyttsp_spi_probe,
0179 };
0180
0181 module_spi_driver(cyttsp_spi_driver);
0182
0183 MODULE_LICENSE("GPL");
0184 MODULE_DESCRIPTION("Cypress TrueTouch(R) Standard Product (TTSP) SPI driver");
0185 MODULE_AUTHOR("Cypress");
0186 MODULE_ALIAS("spi:cyttsp");