drivers/iio/pressure/mpl115_spi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Freescale MPL115A1 pressure/temperature sensor
   4  *
   5  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
   6  *
   7  * Datasheet: http://www.nxp.com/files/sensors/doc/data_sheet/MPL115A1.pdf
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/spi/spi.h>
  12
  13 #include "mpl115.h"
  14
  15 #define MPL115_SPI_WRITE(address)       ((address) << 1)
  16 #define MPL115_SPI_READ(address)        (0x80 | (address) << 1)
  17
  18 struct mpl115_spi_buf {
  19         u8 tx[4];
  20         u8 rx[4];
  21 };
  22
  23 static int mpl115_spi_init(struct device *dev)
  24 {
  25         struct spi_device *spi = to_spi_device(dev);
  26         struct mpl115_spi_buf *buf;
  27
  28         buf = devm_kzalloc(dev, sizeof(*buf), GFP_KERNEL);
  29         if (!buf)
  30                 return -ENOMEM;
  31
  32         spi_set_drvdata(spi, buf);
  33
  34         return 0;
  35 }
  36
  37 static int mpl115_spi_read(struct device *dev, u8 address)
  38 {
  39         struct spi_device *spi = to_spi_device(dev);
  40         struct mpl115_spi_buf *buf = spi_get_drvdata(spi);
  41         struct spi_transfer xfer = {
  42                 .tx_buf = buf->tx,
  43                 .rx_buf = buf->rx,
  44                 .len = 4,
  45         };
  46         int ret;
  47
  48         buf->tx[0] = MPL115_SPI_READ(address);
  49         buf->tx[2] = MPL115_SPI_READ(address + 1);
  50
  51         ret = spi_sync_transfer(spi, &xfer, 1);
  52         if (ret)
  53                 return ret;
  54
  55         return (buf->rx[1] << 8) | buf->rx[3];
  56 }
  57
  58 static int mpl115_spi_write(struct device *dev, u8 address, u8 value)
  59 {
  60         struct spi_device *spi = to_spi_device(dev);
  61         struct mpl115_spi_buf *buf = spi_get_drvdata(spi);
  62         struct spi_transfer xfer = {
  63                 .tx_buf = buf->tx,
  64                 .len = 2,
  65         };
  66
  67         buf->tx[0] = MPL115_SPI_WRITE(address);
  68         buf->tx[1] = value;
  69
  70         return spi_sync_transfer(spi, &xfer, 1);
  71 }
  72
  73 static const struct mpl115_ops mpl115_spi_ops = {
  74         .init = mpl115_spi_init,
  75         .read = mpl115_spi_read,
  76         .write = mpl115_spi_write,
  77 };
  78
  79 static int mpl115_spi_probe(struct spi_device *spi)
  80 {
  81         const struct spi_device_id *id = spi_get_device_id(spi);
  82
  83         return mpl115_probe(&spi->dev, id->name, &mpl115_spi_ops);
  84 }
  85
  86 static const struct spi_device_id mpl115_spi_ids[] = {
  87         { "mpl115", 0 },
  88         {}
  89 };
  90 MODULE_DEVICE_TABLE(spi, mpl115_spi_ids);
  91
  92 static struct spi_driver mpl115_spi_driver = {
  93         .driver = {
  94                 .name   = "mpl115",
  95         },
  96         .probe = mpl115_spi_probe,
  97         .id_table = mpl115_spi_ids,
  98 };
  99 module_spi_driver(mpl115_spi_driver);
 100
 101 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 102 MODULE_DESCRIPTION("Freescale MPL115A1 pressure/temperature driver");
 103 MODULE_LICENSE("GPL");