drivers/iio/humidity/hts221_spi.c

   1 /*
   2  * STMicroelectronics hts221 spi driver
   3  *
   4  * Copyright 2016 STMicroelectronics Inc.
   5  *
   6  * Lorenzo Bianconi <lorenzo.bianconi@st.com>
   7  *
   8  * Licensed under the GPL-2.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/spi/spi.h>
  14 #include <linux/slab.h>
  15 #include "hts221.h"
  16
  17 #define SENSORS_SPI_READ        0x80
  18 #define SPI_AUTO_INCREMENT      0x40
  19
  20 static int hts221_spi_read(struct device *dev, u8 addr, int len, u8 *data)
  21 {
  22         int err;
  23         struct spi_device *spi = to_spi_device(dev);
  24         struct iio_dev *iio_dev = spi_get_drvdata(spi);
  25         struct hts221_hw *hw = iio_priv(iio_dev);
  26
  27         struct spi_transfer xfers[] = {
  28                 {
  29                         .tx_buf = hw->tb.tx_buf,
  30                         .bits_per_word = 8,
  31                         .len = 1,
  32                 },
  33                 {
  34                         .rx_buf = hw->tb.rx_buf,
  35                         .bits_per_word = 8,
  36                         .len = len,
  37                 }
  38         };
  39
  40         if (len > 1)
  41                 addr |= SPI_AUTO_INCREMENT;
  42         hw->tb.tx_buf[0] = addr | SENSORS_SPI_READ;
  43
  44         err = spi_sync_transfer(spi, xfers,  ARRAY_SIZE(xfers));
  45         if (err < 0)
  46                 return err;
  47
  48         memcpy(data, hw->tb.rx_buf, len * sizeof(u8));
  49
  50         return len;
  51 }
  52
  53 static int hts221_spi_write(struct device *dev, u8 addr, int len, u8 *data)
  54 {
  55         struct spi_device *spi = to_spi_device(dev);
  56         struct iio_dev *iio_dev = spi_get_drvdata(spi);
  57         struct hts221_hw *hw = iio_priv(iio_dev);
  58
  59         struct spi_transfer xfers = {
  60                 .tx_buf = hw->tb.tx_buf,
  61                 .bits_per_word = 8,
  62                 .len = len + 1,
  63         };
  64
  65         if (len >= HTS221_TX_MAX_LENGTH)
  66                 return -ENOMEM;
  67
  68         if (len > 1)
  69                 addr |= SPI_AUTO_INCREMENT;
  70         hw->tb.tx_buf[0] = addr;
  71         memcpy(&hw->tb.tx_buf[1], data, len);
  72
  73         return spi_sync_transfer(spi, &xfers, 1);
  74 }
  75
  76 static const struct hts221_transfer_function hts221_transfer_fn = {
  77         .read = hts221_spi_read,
  78         .write = hts221_spi_write,
  79 };
  80
  81 static int hts221_spi_probe(struct spi_device *spi)
  82 {
  83         return hts221_probe(&spi->dev, spi->irq,
  84                             spi->modalias, &hts221_transfer_fn);
  85 }
  86
  87 static const struct of_device_id hts221_spi_of_match[] = {
  88         { .compatible = "st,hts221", },
  89         {},
  90 };
  91 MODULE_DEVICE_TABLE(of, hts221_spi_of_match);
  92
  93 static const struct spi_device_id hts221_spi_id_table[] = {
  94         { HTS221_DEV_NAME },
  95         {},
  96 };
  97 MODULE_DEVICE_TABLE(spi, hts221_spi_id_table);
  98
  99 static struct spi_driver hts221_driver = {
 100         .driver = {
 101                 .name = "hts221_spi",
 102                 .pm = &hts221_pm_ops,
 103                 .of_match_table = of_match_ptr(hts221_spi_of_match),
 104         },
 105         .probe = hts221_spi_probe,
 106         .id_table = hts221_spi_id_table,
 107 };
 108 module_spi_driver(hts221_driver);
 109
 110 MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
 111 MODULE_DESCRIPTION("STMicroelectronics hts221 spi driver");
 112 MODULE_LICENSE("GPL v2");