drivers/iio/adc/ltc2496.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ltc2496.c - Driver for Analog Devices/Linear Technology LTC2496 ADC
   4  *
   5  * Based on ltc2497.c which has
   6  * Copyright (C) 2017 Analog Devices Inc.
   7  *
   8  * Licensed under the GPL-2.
   9  *
  10  * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2496fc.pdf
  11  */
  12
  13 #include <linux/spi/spi.h>
  14 #include <linux/iio/iio.h>
  15 #include <linux/iio/driver.h>
  16 #include <linux/module.h>
  17 #include <linux/mod_devicetable.h>
  18
  19 #include "ltc2497.h"
  20
  21 struct ltc2496_driverdata {
  22         /* this must be the first member */
  23         struct ltc2497core_driverdata common_ddata;
  24         struct spi_device *spi;
  25
  26         /*
  27          * DMA (thus cache coherency maintenance) requires the
  28          * transfer buffers to live in their own cache lines.
  29          */
  30         unsigned char rxbuf[3] ____cacheline_aligned;
  31         unsigned char txbuf[3];
  32 };
  33
  34 static int ltc2496_result_and_measure(struct ltc2497core_driverdata *ddata,
  35                                       u8 address, int *val)
  36 {
  37         struct ltc2496_driverdata *st =
  38                 container_of(ddata, struct ltc2496_driverdata, common_ddata);
  39         struct spi_transfer t = {
  40                 .tx_buf = st->txbuf,
  41                 .rx_buf = st->rxbuf,
  42                 .len = sizeof(st->txbuf),
  43         };
  44         int ret;
  45
  46         st->txbuf[0] = LTC2497_ENABLE | address;
  47
  48         ret = spi_sync_transfer(st->spi, &t, 1);
  49         if (ret < 0)  {
  50                 dev_err(&st->spi->dev, "spi_sync_transfer failed: %pe\n",
  51                         ERR_PTR(ret));
  52                 return ret;
  53         }
  54
  55         if (val)
  56                 *val = ((st->rxbuf[0] & 0x3f) << 12 |
  57                         st->rxbuf[1] << 4 | st->rxbuf[2] >> 4) -
  58                         (1 << 17);
  59
  60         return 0;
  61 }
  62
  63 static int ltc2496_probe(struct spi_device *spi)
  64 {
  65         struct iio_dev *indio_dev;
  66         struct ltc2496_driverdata *st;
  67         struct device *dev = &spi->dev;
  68
  69         indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
  70         if (!indio_dev)
  71                 return -ENOMEM;
  72
  73         st = iio_priv(indio_dev);
  74         spi_set_drvdata(spi, indio_dev);
  75         st->spi = spi;
  76         st->common_ddata.result_and_measure = ltc2496_result_and_measure;
  77
  78         return ltc2497core_probe(dev, indio_dev);
  79 }
  80
  81 static int ltc2496_remove(struct spi_device *spi)
  82 {
  83         struct iio_dev *indio_dev = spi_get_drvdata(spi);
  84
  85         ltc2497core_remove(indio_dev);
  86
  87         return 0;
  88 }
  89
  90 static const struct of_device_id ltc2496_of_match[] = {
  91         { .compatible = "lltc,ltc2496", },
  92         {},
  93 };
  94 MODULE_DEVICE_TABLE(of, ltc2496_of_match);
  95
  96 static struct spi_driver ltc2496_driver = {
  97         .driver = {
  98                 .name = "ltc2496",
  99                 .of_match_table = ltc2496_of_match,
 100         },
 101         .probe = ltc2496_probe,
 102         .remove = ltc2496_remove,
 103 };
 104 module_spi_driver(ltc2496_driver);
 105
 106 MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
 107 MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
 108 MODULE_LICENSE("GPL v2");