LXR linux/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
  21struct 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
  34static 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
  63static 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
  81static 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
  90static const struct of_device_id ltc2496_of_match[] = {
  91        { .compatible = "lltc,ltc2496", },
  92        {},
  93};
  94MODULE_DEVICE_TABLE(of, ltc2496_of_match);
  95
  96static 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};
 104module_spi_driver(ltc2496_driver);
 105
 106MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
 107MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
 108MODULE_LICENSE("GPL v2");
 109