LXR linux/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
  30static 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
  82static 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
  90static 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
  98static 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
 106static 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
 113static 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
 140static 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
 149static 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
 159module_spi_driver(ad7879_spi_driver);
 160
 161MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 162MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
 163MODULE_LICENSE("GPL");
 164MODULE_ALIAS("spi:ad7879");
 165