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 #include <linux/property.h>
  19
  20 #include "ltc2497.h"
  21
  22 struct ltc2496_driverdata {
  23         /* this must be the first member */
  24         struct ltc2497core_driverdata common_ddata;
  25         struct spi_device *spi;
  26
  27         /*
  28          * DMA (thus cache coherency maintenance) may require the
  29          * transfer buffers to live in their own cache lines.
  30          */
  31         unsigned char rxbuf[3] __aligned(IIO_DMA_MINALIGN);
  32         unsigned char txbuf[3];
  33 };
  34
  35 static int ltc2496_result_and_measure(struct ltc2497core_driverdata *ddata,
  36                                       u8 address, int *val)
  37 {
  38         struct ltc2496_driverdata *st =
  39                 container_of(ddata, struct ltc2496_driverdata, common_ddata);
  40         struct spi_transfer t = {
  41                 .tx_buf = st->txbuf,
  42                 .rx_buf = st->rxbuf,
  43                 .len = sizeof(st->txbuf),
  44         };
  45         int ret;
  46
  47         st->txbuf[0] = LTC2497_ENABLE | address;
  48
  49         ret = spi_sync_transfer(st->spi, &t, 1);
  50         if (ret < 0)  {
  51                 dev_err(&st->spi->dev, "spi_sync_transfer failed: %pe\n",
  52                         ERR_PTR(ret));
  53                 return ret;
  54         }
  55
  56         if (val)
  57                 *val = ((st->rxbuf[0] & 0x3f) << 12 |
  58                         st->rxbuf[1] << 4 | st->rxbuf[2] >> 4) -
  59                         (1 << 17);
  60
  61         return 0;
  62 }
  63
  64 static int ltc2496_probe(struct spi_device *spi)
  65 {
  66         struct iio_dev *indio_dev;
  67         struct ltc2496_driverdata *st;
  68         struct device *dev = &spi->dev;
  69
  70         indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
  71         if (!indio_dev)
  72                 return -ENOMEM;
  73
  74         st = iio_priv(indio_dev);
  75         spi_set_drvdata(spi, indio_dev);
  76         st->spi = spi;
  77         st->common_ddata.result_and_measure = ltc2496_result_and_measure;
  78         st->common_ddata.chip_info = device_get_match_data(dev);
  79
  80         return ltc2497core_probe(dev, indio_dev);
  81 }
  82
  83 static void ltc2496_remove(struct spi_device *spi)
  84 {
  85         struct iio_dev *indio_dev = spi_get_drvdata(spi);
  86
  87         ltc2497core_remove(indio_dev);
  88 }
  89
  90 static const struct ltc2497_chip_info ltc2496_info = {
  91         .resolution = 16,
  92         .name = NULL,
  93 };
  94
  95 static const struct of_device_id ltc2496_of_match[] = {
  96         { .compatible = "lltc,ltc2496", .data = &ltc2496_info, },
  97         { }
  98 };
  99 MODULE_DEVICE_TABLE(of, ltc2496_of_match);
 100
 101 static struct spi_driver ltc2496_driver = {
 102         .driver = {
 103                 .name = "ltc2496",
 104                 .of_match_table = ltc2496_of_match,
 105         },
 106         .probe = ltc2496_probe,
 107         .remove = ltc2496_remove,
 108 };
 109 module_spi_driver(ltc2496_driver);
 110
 111 MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
 112 MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
 113 MODULE_LICENSE("GPL v2");