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/spi/spi.h>
  11
  12 #include "ad7879.h"
  13
  14 #define AD7879_DEVID            0x7A    /* AD7879/AD7889 */
  15
  16 #define MAX_SPI_FREQ_HZ      5000000
  17 #define AD7879_CMD_MAGIC     0xE000
  18 #define AD7879_CMD_READ      (1 << 10)
  19 #define AD7879_CMD(reg)      (AD7879_CMD_MAGIC | ((reg) & 0xF))
  20 #define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
  21 #define AD7879_READCMD(reg)  (AD7879_CMD(reg) | AD7879_CMD_READ)
  22
  23 #ifdef CONFIG_PM
  24 static int ad7879_spi_suspend(struct spi_device *spi, pm_message_t message)
  25 {
  26         struct ad7879 *ts = spi_get_drvdata(spi);
  27
  28         ad7879_disable(ts);
  29
  30         return 0;
  31 }
  32
  33 static int ad7879_spi_resume(struct spi_device *spi)
  34 {
  35         struct ad7879 *ts = spi_get_drvdata(spi);
  36
  37         ad7879_enable(ts);
  38
  39         return 0;
  40 }
  41 #else
  42 # define ad7879_spi_suspend NULL
  43 # define ad7879_spi_resume  NULL
  44 #endif
  45
  46 /*
  47  * ad7879_read/write are only used for initial setup and for sysfs controls.
  48  * The main traffic is done in ad7879_collect().
  49  */
  50
  51 static int ad7879_spi_xfer(struct spi_device *spi,
  52                            u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
  53 {
  54         struct spi_message msg;
  55         struct spi_transfer *xfers;
  56         void *spi_data;
  57         u16 *command;
  58         u16 *_rx_buf = _rx_buf; /* shut gcc up */
  59         u8 idx;
  60         int ret;
  61
  62         xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
  63         if (!spi_data)
  64                 return -ENOMEM;
  65
  66         spi_message_init(&msg);
  67
  68         command = spi_data;
  69         command[0] = cmd;
  70         if (count == 1) {
  71                 /* ad7879_spi_{read,write} gave us buf on stack */
  72                 command[1] = *tx_buf;
  73                 tx_buf = &command[1];
  74                 _rx_buf = rx_buf;
  75                 rx_buf = &command[2];
  76         }
  77
  78         ++xfers;
  79         xfers[0].tx_buf = command;
  80         xfers[0].len = 2;
  81         spi_message_add_tail(&xfers[0], &msg);
  82         ++xfers;
  83
  84         for (idx = 0; idx < count; ++idx) {
  85                 if (rx_buf)
  86                         xfers[idx].rx_buf = &rx_buf[idx];
  87                 if (tx_buf)
  88                         xfers[idx].tx_buf = &tx_buf[idx];
  89                 xfers[idx].len = 2;
  90                 spi_message_add_tail(&xfers[idx], &msg);
  91         }
  92
  93         ret = spi_sync(spi, &msg);
  94
  95         if (count == 1)
  96                 _rx_buf[0] = command[2];
  97
  98         kfree(spi_data);
  99
 100         return ret;
 101 }
 102
 103 static int ad7879_spi_multi_read(struct device *dev,
 104                                  u8 first_reg, u8 count, u16 *buf)
 105 {
 106         struct spi_device *spi = to_spi_device(dev);
 107
 108         return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
 109 }
 110
 111 static int ad7879_spi_read(struct device *dev, u8 reg)
 112 {
 113         struct spi_device *spi = to_spi_device(dev);
 114         u16 ret, dummy;
 115
 116         return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
 117 }
 118
 119 static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
 120 {
 121         struct spi_device *spi = to_spi_device(dev);
 122         u16 dummy;
 123
 124         return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
 125 }
 126
 127 static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
 128         .bustype        = BUS_SPI,
 129         .read           = ad7879_spi_read,
 130         .multi_read     = ad7879_spi_multi_read,
 131         .write          = ad7879_spi_write,
 132 };
 133
 134 static int __devinit ad7879_spi_probe(struct spi_device *spi)
 135 {
 136         struct ad7879 *ts;
 137
 138         /* don't exceed max specified SPI CLK frequency */
 139         if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
 140                 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
 141                 return -EINVAL;
 142         }
 143
 144         ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
 145         if (IS_ERR(ts))
 146                 return PTR_ERR(ts);
 147
 148         spi_set_drvdata(spi, ts);
 149
 150         return 0;
 151 }
 152
 153 static int __devexit ad7879_spi_remove(struct spi_device *spi)
 154 {
 155         struct ad7879 *ts = spi_get_drvdata(spi);
 156
 157         ad7879_remove(ts);
 158         spi_set_drvdata(spi, NULL);
 159
 160         return 0;
 161 }
 162
 163 static struct spi_driver ad7879_spi_driver = {
 164         .driver = {
 165                 .name   = "ad7879",
 166                 .bus    = &spi_bus_type,
 167                 .owner  = THIS_MODULE,
 168         },
 169         .probe          = ad7879_spi_probe,
 170         .remove         = __devexit_p(ad7879_spi_remove),
 171         .suspend        = ad7879_spi_suspend,
 172         .resume         = ad7879_spi_resume,
 173 };
 174
 175 static int __init ad7879_spi_init(void)
 176 {
 177         return spi_register_driver(&ad7879_spi_driver);
 178 }
 179 module_init(ad7879_spi_init);
 180
 181 static void __exit ad7879_spi_exit(void)
 182 {
 183         spi_unregister_driver(&ad7879_spi_driver);
 184 }
 185 module_exit(ad7879_spi_exit);
 186
 187 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 188 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
 189 MODULE_LICENSE("GPL");
 190 MODULE_ALIAS("spi:ad7879");