drivers/input/touchscreen/ad7879-spi.c

   1 /*
   2  * AD7879/AD7889 touchscreen (SPI bus)
   3  *
   4  * Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/input.h>        /* BUS_SPI */
  10 #include <linux/pm.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/module.h>
  13
  14 #include "ad7879.h"
  15
  16 #define AD7879_DEVID            0x7A    /* AD7879/AD7889 */
  17
  18 #define MAX_SPI_FREQ_HZ      5000000
  19 #define AD7879_CMD_MAGIC     0xE000
  20 #define AD7879_CMD_READ      (1 << 10)
  21 #define AD7879_CMD(reg)      (AD7879_CMD_MAGIC | ((reg) & 0xF))
  22 #define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
  23 #define AD7879_READCMD(reg)  (AD7879_CMD(reg) | AD7879_CMD_READ)
  24
  25 /*
  26  * ad7879_read/write are only used for initial setup and for sysfs controls.
  27  * The main traffic is done in ad7879_collect().
  28  */
  29
  30 static int ad7879_spi_xfer(struct spi_device *spi,
  31                            u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
  32 {
  33         struct spi_message msg;
  34         struct spi_transfer *xfers;
  35         void *spi_data;
  36         u16 *command;
  37         u16 *_rx_buf = _rx_buf; /* shut gcc up */
  38         u8 idx;
  39         int ret;
  40
  41         xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
  42         if (!spi_data)
  43                 return -ENOMEM;
  44
  45         spi_message_init(&msg);
  46
  47         command = spi_data;
  48         command[0] = cmd;
  49         if (count == 1) {
  50                 /* ad7879_spi_{read,write} gave us buf on stack */
  51                 command[1] = *tx_buf;
  52                 tx_buf = &command[1];
  53                 _rx_buf = rx_buf;
  54                 rx_buf = &command[2];
  55         }
  56
  57         ++xfers;
  58         xfers[0].tx_buf = command;
  59         xfers[0].len = 2;
  60         spi_message_add_tail(&xfers[0], &msg);
  61         ++xfers;
  62
  63         for (idx = 0; idx < count; ++idx) {
  64                 if (rx_buf)
  65                         xfers[idx].rx_buf = &rx_buf[idx];
  66                 if (tx_buf)
  67                         xfers[idx].tx_buf = &tx_buf[idx];
  68                 xfers[idx].len = 2;
  69                 spi_message_add_tail(&xfers[idx], &msg);
  70         }
  71
  72         ret = spi_sync(spi, &msg);
  73
  74         if (count == 1)
  75                 _rx_buf[0] = command[2];
  76
  77         kfree(spi_data);
  78
  79         return ret;
  80 }
  81
  82 static int ad7879_spi_multi_read(struct device *dev,
  83                                  u8 first_reg, u8 count, u16 *buf)
  84 {
  85         struct spi_device *spi = to_spi_device(dev);
  86
  87         return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
  88 }
  89
  90 static int ad7879_spi_read(struct device *dev, u8 reg)
  91 {
  92         struct spi_device *spi = to_spi_device(dev);
  93         u16 ret, dummy;
  94
  95         return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
  96 }
  97
  98 static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
  99 {
 100         struct spi_device *spi = to_spi_device(dev);
 101         u16 dummy;
 102
 103         return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
 104 }
 105
 106 static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
 107         .bustype        = BUS_SPI,
 108         .read           = ad7879_spi_read,
 109         .multi_read     = ad7879_spi_multi_read,
 110         .write          = ad7879_spi_write,
 111 };
 112
 113 static int ad7879_spi_probe(struct spi_device *spi)
 114 {
 115         struct ad7879 *ts;
 116         int err;
 117
 118         /* don't exceed max specified SPI CLK frequency */
 119         if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
 120                 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
 121                 return -EINVAL;
 122         }
 123
 124         spi->bits_per_word = 16;
 125         err = spi_setup(spi);
 126         if (err) {
 127                 dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
 128                 return err;
 129         }
 130
 131         ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
 132         if (IS_ERR(ts))
 133                 return PTR_ERR(ts);
 134
 135         spi_set_drvdata(spi, ts);
 136
 137         return 0;
 138 }
 139
 140 static int ad7879_spi_remove(struct spi_device *spi)
 141 {
 142         struct ad7879 *ts = spi_get_drvdata(spi);
 143
 144         ad7879_remove(ts);
 145
 146         return 0;
 147 }
 148
 149 static struct spi_driver ad7879_spi_driver = {
 150         .driver = {
 151                 .name   = "ad7879",
 152                 .owner  = THIS_MODULE,
 153                 .pm     = &ad7879_pm_ops,
 154         },
 155         .probe          = ad7879_spi_probe,
 156         .remove         = ad7879_spi_remove,
 157 };
 158
 159 module_spi_driver(ad7879_spi_driver);
 160
 161 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 162 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
 163 MODULE_LICENSE("GPL");
 164 MODULE_ALIAS("spi:ad7879");