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
  13 #include "ad7879.h"
  14
  15 #define AD7879_DEVID            0x7A    /* AD7879/AD7889 */
  16
  17 #define MAX_SPI_FREQ_HZ      5000000
  18 #define AD7879_CMD_MAGIC     0xE000
  19 #define AD7879_CMD_READ      (1 << 10)
  20 #define AD7879_CMD(reg)      (AD7879_CMD_MAGIC | ((reg) & 0xF))
  21 #define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
  22 #define AD7879_READCMD(reg)  (AD7879_CMD(reg) | AD7879_CMD_READ)
  23
  24 #ifdef CONFIG_PM_SLEEP
  25 static int ad7879_spi_suspend(struct device *dev)
  26 {
  27         struct spi_device *spi = to_spi_device(dev);
  28         struct ad7879 *ts = spi_get_drvdata(spi);
  29
  30         ad7879_suspend(ts);
  31
  32         return 0;
  33 }
  34
  35 static int ad7879_spi_resume(struct device *dev)
  36 {
  37         struct spi_device *spi = to_spi_device(dev);
  38         struct ad7879 *ts = spi_get_drvdata(spi);
  39
  40         ad7879_resume(ts);
  41
  42         return 0;
  43 }
  44 #endif
  45
  46 static SIMPLE_DEV_PM_OPS(ad7879_spi_pm, ad7879_spi_suspend, ad7879_spi_resume);
  47
  48 /*
  49  * ad7879_read/write are only used for initial setup and for sysfs controls.
  50  * The main traffic is done in ad7879_collect().
  51  */
  52
  53 static int ad7879_spi_xfer(struct spi_device *spi,
  54                            u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
  55 {
  56         struct spi_message msg;
  57         struct spi_transfer *xfers;
  58         void *spi_data;
  59         u16 *command;
  60         u16 *_rx_buf = _rx_buf; /* shut gcc up */
  61         u8 idx;
  62         int ret;
  63
  64         xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
  65         if (!spi_data)
  66                 return -ENOMEM;
  67
  68         spi_message_init(&msg);
  69
  70         command = spi_data;
  71         command[0] = cmd;
  72         if (count == 1) {
  73                 /* ad7879_spi_{read,write} gave us buf on stack */
  74                 command[1] = *tx_buf;
  75                 tx_buf = &command[1];
  76                 _rx_buf = rx_buf;
  77                 rx_buf = &command[2];
  78         }
  79
  80         ++xfers;
  81         xfers[0].tx_buf = command;
  82         xfers[0].len = 2;
  83         spi_message_add_tail(&xfers[0], &msg);
  84         ++xfers;
  85
  86         for (idx = 0; idx < count; ++idx) {
  87                 if (rx_buf)
  88                         xfers[idx].rx_buf = &rx_buf[idx];
  89                 if (tx_buf)
  90                         xfers[idx].tx_buf = &tx_buf[idx];
  91                 xfers[idx].len = 2;
  92                 spi_message_add_tail(&xfers[idx], &msg);
  93         }
  94
  95         ret = spi_sync(spi, &msg);
  96
  97         if (count == 1)
  98                 _rx_buf[0] = command[2];
  99
 100         kfree(spi_data);
 101
 102         return ret;
 103 }
 104
 105 static int ad7879_spi_multi_read(struct device *dev,
 106                                  u8 first_reg, u8 count, u16 *buf)
 107 {
 108         struct spi_device *spi = to_spi_device(dev);
 109
 110         return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
 111 }
 112
 113 static int ad7879_spi_read(struct device *dev, u8 reg)
 114 {
 115         struct spi_device *spi = to_spi_device(dev);
 116         u16 ret, dummy;
 117
 118         return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
 119 }
 120
 121 static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
 122 {
 123         struct spi_device *spi = to_spi_device(dev);
 124         u16 dummy;
 125
 126         return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
 127 }
 128
 129 static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
 130         .bustype        = BUS_SPI,
 131         .read           = ad7879_spi_read,
 132         .multi_read     = ad7879_spi_multi_read,
 133         .write          = ad7879_spi_write,
 134 };
 135
 136 static int __devinit ad7879_spi_probe(struct spi_device *spi)
 137 {
 138         struct ad7879 *ts;
 139         int err;
 140
 141         /* don't exceed max specified SPI CLK frequency */
 142         if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
 143                 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
 144                 return -EINVAL;
 145         }
 146
 147         spi->bits_per_word = 16;
 148         err = spi_setup(spi);
 149         if (err) {
 150                 dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
 151                 return err;
 152         }
 153
 154         ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
 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 int __devexit ad7879_spi_remove(struct spi_device *spi)
 164 {
 165         struct ad7879 *ts = spi_get_drvdata(spi);
 166
 167         ad7879_remove(ts);
 168         spi_set_drvdata(spi, NULL);
 169
 170         return 0;
 171 }
 172
 173 static struct spi_driver ad7879_spi_driver = {
 174         .driver = {
 175                 .name   = "ad7879",
 176                 .bus    = &spi_bus_type,
 177                 .owner  = THIS_MODULE,
 178                 .pm     = &ad7879_spi_pm,
 179         },
 180         .probe          = ad7879_spi_probe,
 181         .remove         = __devexit_p(ad7879_spi_remove),
 182 };
 183
 184 static int __init ad7879_spi_init(void)
 185 {
 186         return spi_register_driver(&ad7879_spi_driver);
 187 }
 188 module_init(ad7879_spi_init);
 189
 190 static void __exit ad7879_spi_exit(void)
 191 {
 192         spi_unregister_driver(&ad7879_spi_driver);
 193 }
 194 module_exit(ad7879_spi_exit);
 195
 196 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 197 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
 198 MODULE_LICENSE("GPL");
 199 MODULE_ALIAS("spi:ad7879");