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#include <linux/of.h>
  14
  15#include "ad7879.h"
  16
  17#define AD7879_DEVID            0x7A    /* AD7879/AD7889 */
  18
  19#define MAX_SPI_FREQ_HZ      5000000
  20#define AD7879_CMD_MAGIC     0xE000
  21#define AD7879_CMD_READ      (1 << 10)
  22#define AD7879_CMD(reg)      (AD7879_CMD_MAGIC | ((reg) & 0xF))
  23#define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
  24#define AD7879_READCMD(reg)  (AD7879_CMD(reg) | AD7879_CMD_READ)
  25
  26/*
  27 * ad7879_read/write are only used for initial setup and for sysfs controls.
  28 * The main traffic is done in ad7879_collect().
  29 */
  30
  31static int ad7879_spi_xfer(struct spi_device *spi,
  32                           u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
  33{
  34        struct spi_message msg;
  35        struct spi_transfer *xfers;
  36        void *spi_data;
  37        u16 *command;
  38        u16 *_rx_buf = _rx_buf; /* shut gcc up */
  39        u8 idx;
  40        int ret;
  41
  42        xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
  43        if (!spi_data)
  44                return -ENOMEM;
  45
  46        spi_message_init(&msg);
  47
  48        command = spi_data;
  49        command[0] = cmd;
  50        if (count == 1) {
  51                /* ad7879_spi_{read,write} gave us buf on stack */
  52                command[1] = *tx_buf;
  53                tx_buf = &command[1];
  54                _rx_buf = rx_buf;
  55                rx_buf = &command[2];
  56        }
  57
  58        ++xfers;
  59        xfers[0].tx_buf = command;
  60        xfers[0].len = 2;
  61        spi_message_add_tail(&xfers[0], &msg);
  62        ++xfers;
  63
  64        for (idx = 0; idx < count; ++idx) {
  65                if (rx_buf)
  66                        xfers[idx].rx_buf = &rx_buf[idx];
  67                if (tx_buf)
  68                        xfers[idx].tx_buf = &tx_buf[idx];
  69                xfers[idx].len = 2;
  70                spi_message_add_tail(&xfers[idx], &msg);
  71        }
  72
  73        ret = spi_sync(spi, &msg);
  74
  75        if (count == 1)
  76                _rx_buf[0] = command[2];
  77
  78        kfree(spi_data);
  79
  80        return ret;
  81}
  82
  83static int ad7879_spi_multi_read(struct device *dev,
  84                                 u8 first_reg, u8 count, u16 *buf)
  85{
  86        struct spi_device *spi = to_spi_device(dev);
  87
  88        return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
  89}
  90
  91static int ad7879_spi_read(struct device *dev, u8 reg)
  92{
  93        struct spi_device *spi = to_spi_device(dev);
  94        u16 ret, dummy;
  95
  96        return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
  97}
  98
  99static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
 100{
 101        struct spi_device *spi = to_spi_device(dev);
 102        u16 dummy;
 103
 104        return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
 105}
 106
 107static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
 108        .bustype        = BUS_SPI,
 109        .read           = ad7879_spi_read,
 110        .multi_read     = ad7879_spi_multi_read,
 111        .write          = ad7879_spi_write,
 112};
 113
 114static int ad7879_spi_probe(struct spi_device *spi)
 115{
 116        struct ad7879 *ts;
 117        int err;
 118
 119        /* don't exceed max specified SPI CLK frequency */
 120        if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
 121                dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
 122                return -EINVAL;
 123        }
 124
 125        spi->bits_per_word = 16;
 126        err = spi_setup(spi);
 127        if (err) {
 128                dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
 129                return err;
 130        }
 131
 132        ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
 133        if (IS_ERR(ts))
 134                return PTR_ERR(ts);
 135
 136        spi_set_drvdata(spi, ts);
 137
 138        return 0;
 139}
 140
 141static int ad7879_spi_remove(struct spi_device *spi)
 142{
 143        struct ad7879 *ts = spi_get_drvdata(spi);
 144
 145        ad7879_remove(ts);
 146
 147        return 0;
 148}
 149
 150#ifdef CONFIG_OF
 151static const struct of_device_id ad7879_spi_dt_ids[] = {
 152        { .compatible = "adi,ad7879", },
 153        { }
 154};
 155MODULE_DEVICE_TABLE(of, ad7879_spi_dt_ids);
 156#endif
 157
 158static struct spi_driver ad7879_spi_driver = {
 159        .driver = {
 160                .name   = "ad7879",
 161                .pm     = &ad7879_pm_ops,
 162                .of_match_table = of_match_ptr(ad7879_spi_dt_ids),
 163        },
 164        .probe          = ad7879_spi_probe,
 165        .remove         = ad7879_spi_remove,
 166};
 167
 168module_spi_driver(ad7879_spi_driver);
 169
 170MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 171MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
 172MODULE_LICENSE("GPL");
 173MODULE_ALIAS("spi:ad7879");
 174