drivers/input/misc/ad714x-spi.c

   1 /*
   2  * AD714X CapTouch Programmable Controller driver (SPI bus)
   3  *
   4  * Copyright 2009-2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/input.h>        /* BUS_SPI */
  10 #include <linux/module.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/pm.h>
  13 #include <linux/types.h>
  14 #include "ad714x.h"
  15
  16 #define AD714x_SPI_CMD_PREFIX      0xE000   /* bits 15:11 */
  17 #define AD714x_SPI_READ            BIT(10)
  18
  19 static int __maybe_unused ad714x_spi_suspend(struct device *dev)
  20 {
  21         return ad714x_disable(spi_get_drvdata(to_spi_device(dev)));
  22 }
  23
  24 static int __maybe_unused ad714x_spi_resume(struct device *dev)
  25 {
  26         return ad714x_enable(spi_get_drvdata(to_spi_device(dev)));
  27 }
  28
  29 static SIMPLE_DEV_PM_OPS(ad714x_spi_pm, ad714x_spi_suspend, ad714x_spi_resume);
  30
  31 static int ad714x_spi_read(struct ad714x_chip *chip,
  32                            unsigned short reg, unsigned short *data, size_t len)
  33 {
  34         struct spi_device *spi = to_spi_device(chip->dev);
  35         struct spi_message message;
  36         struct spi_transfer xfer[2];
  37         int i;
  38         int error;
  39
  40         spi_message_init(&message);
  41         memset(xfer, 0, sizeof(xfer));
  42
  43         chip->xfer_buf[0] = cpu_to_be16(AD714x_SPI_CMD_PREFIX |
  44                                         AD714x_SPI_READ | reg);
  45         xfer[0].tx_buf = &chip->xfer_buf[0];
  46         xfer[0].len = sizeof(chip->xfer_buf[0]);
  47         spi_message_add_tail(&xfer[0], &message);
  48
  49         xfer[1].rx_buf = &chip->xfer_buf[1];
  50         xfer[1].len = sizeof(chip->xfer_buf[1]) * len;
  51         spi_message_add_tail(&xfer[1], &message);
  52
  53         error = spi_sync(spi, &message);
  54         if (unlikely(error)) {
  55                 dev_err(chip->dev, "SPI read error: %d\n", error);
  56                 return error;
  57         }
  58
  59         for (i = 0; i < len; i++)
  60                 data[i] = be16_to_cpu(chip->xfer_buf[i + 1]);
  61
  62         return 0;
  63 }
  64
  65 static int ad714x_spi_write(struct ad714x_chip *chip,
  66                             unsigned short reg, unsigned short data)
  67 {
  68         struct spi_device *spi = to_spi_device(chip->dev);
  69         int error;
  70
  71         chip->xfer_buf[0] = cpu_to_be16(AD714x_SPI_CMD_PREFIX | reg);
  72         chip->xfer_buf[1] = cpu_to_be16(data);
  73
  74         error = spi_write(spi, (u8 *)chip->xfer_buf,
  75                           2 * sizeof(*chip->xfer_buf));
  76         if (unlikely(error)) {
  77                 dev_err(chip->dev, "SPI write error: %d\n", error);
  78                 return error;
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int ad714x_spi_probe(struct spi_device *spi)
  85 {
  86         struct ad714x_chip *chip;
  87         int err;
  88
  89         spi->bits_per_word = 8;
  90         err = spi_setup(spi);
  91         if (err < 0)
  92                 return err;
  93
  94         chip = ad714x_probe(&spi->dev, BUS_SPI, spi->irq,
  95                             ad714x_spi_read, ad714x_spi_write);
  96         if (IS_ERR(chip))
  97                 return PTR_ERR(chip);
  98
  99         spi_set_drvdata(spi, chip);
 100
 101         return 0;
 102 }
 103
 104 static struct spi_driver ad714x_spi_driver = {
 105         .driver = {
 106                 .name   = "ad714x_captouch",
 107                 .pm     = &ad714x_spi_pm,
 108         },
 109         .probe          = ad714x_spi_probe,
 110 };
 111
 112 module_spi_driver(ad714x_spi_driver);
 113
 114 MODULE_DESCRIPTION("Analog Devices AD714X Capacitance Touch Sensor SPI Bus Driver");
 115 MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
 116 MODULE_LICENSE("GPL");