drivers/iio/pressure/mpl115_spi.c

   1 /*
   2  * Freescale MPL115A1 pressure/temperature sensor
   3  *
   4  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
   5  *
   6  * This file is subject to the terms and conditions of version 2 of
   7  * the GNU General Public License.  See the file COPYING in the main
   8  * directory of this archive for more details.
   9  *
  10  * Datasheet: http://www.nxp.com/files/sensors/doc/data_sheet/MPL115A1.pdf
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/spi/spi.h>
  15
  16 #include "mpl115.h"
  17
  18 #define MPL115_SPI_WRITE(address)       ((address) << 1)
  19 #define MPL115_SPI_READ(address)        (0x80 | (address) << 1)
  20
  21 struct mpl115_spi_buf {
  22         u8 tx[4];
  23         u8 rx[4];
  24 };
  25
  26 static int mpl115_spi_init(struct device *dev)
  27 {
  28         struct spi_device *spi = to_spi_device(dev);
  29         struct mpl115_spi_buf *buf;
  30
  31         buf = devm_kzalloc(dev, sizeof(*buf), GFP_KERNEL);
  32         if (!buf)
  33                 return -ENOMEM;
  34
  35         spi_set_drvdata(spi, buf);
  36
  37         return 0;
  38 }
  39
  40 static int mpl115_spi_read(struct device *dev, u8 address)
  41 {
  42         struct spi_device *spi = to_spi_device(dev);
  43         struct mpl115_spi_buf *buf = spi_get_drvdata(spi);
  44         struct spi_transfer xfer = {
  45                 .tx_buf = buf->tx,
  46                 .rx_buf = buf->rx,
  47                 .len = 4,
  48         };
  49         int ret;
  50
  51         buf->tx[0] = MPL115_SPI_READ(address);
  52         buf->tx[2] = MPL115_SPI_READ(address + 1);
  53
  54         ret = spi_sync_transfer(spi, &xfer, 1);
  55         if (ret)
  56                 return ret;
  57
  58         return (buf->rx[1] << 8) | buf->rx[3];
  59 }
  60
  61 static int mpl115_spi_write(struct device *dev, u8 address, u8 value)
  62 {
  63         struct spi_device *spi = to_spi_device(dev);
  64         struct mpl115_spi_buf *buf = spi_get_drvdata(spi);
  65         struct spi_transfer xfer = {
  66                 .tx_buf = buf->tx,
  67                 .len = 2,
  68         };
  69
  70         buf->tx[0] = MPL115_SPI_WRITE(address);
  71         buf->tx[1] = value;
  72
  73         return spi_sync_transfer(spi, &xfer, 1);
  74 }
  75
  76 static const struct mpl115_ops mpl115_spi_ops = {
  77         .init = mpl115_spi_init,
  78         .read = mpl115_spi_read,
  79         .write = mpl115_spi_write,
  80 };
  81
  82 static int mpl115_spi_probe(struct spi_device *spi)
  83 {
  84         const struct spi_device_id *id = spi_get_device_id(spi);
  85
  86         return mpl115_probe(&spi->dev, id->name, &mpl115_spi_ops);
  87 }
  88
  89 static const struct spi_device_id mpl115_spi_ids[] = {
  90         { "mpl115", 0 },
  91         {}
  92 };
  93 MODULE_DEVICE_TABLE(spi, mpl115_spi_ids);
  94
  95 static struct spi_driver mpl115_spi_driver = {
  96         .driver = {
  97                 .name   = "mpl115",
  98         },
  99         .probe = mpl115_spi_probe,
 100         .id_table = mpl115_spi_ids,
 101 };
 102 module_spi_driver(mpl115_spi_driver);
 103
 104 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 105 MODULE_DESCRIPTION("Freescale MPL115A1 pressure/temperature driver");
 106 MODULE_LICENSE("GPL");