drivers/iio/adc/ltc2497.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
   4  *
   5  * Copyright (C) 2017 Analog Devices Inc.
   6  *
   7  * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
   8  */
   9
  10 #include <linux/i2c.h>
  11 #include <linux/iio/iio.h>
  12 #include <linux/iio/driver.h>
  13 #include <linux/module.h>
  14 #include <linux/mod_devicetable.h>
  15
  16 #include "ltc2497.h"
  17
  18 struct ltc2497_driverdata {
  19         /* this must be the first member */
  20         struct ltc2497core_driverdata common_ddata;
  21         struct i2c_client *client;
  22         /*
  23          * DMA (thus cache coherency maintenance) requires the
  24          * transfer buffers to live in their own cache lines.
  25          */
  26         __be32 buf ____cacheline_aligned;
  27 };
  28
  29 static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
  30                                       u8 address, int *val)
  31 {
  32         struct ltc2497_driverdata *st =
  33                 container_of(ddata, struct ltc2497_driverdata, common_ddata);
  34         int ret;
  35
  36         if (val) {
  37                 ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
  38                 if (ret < 0) {
  39                         dev_err(&st->client->dev, "i2c_master_recv failed\n");
  40                         return ret;
  41                 }
  42
  43                 *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
  44         }
  45
  46         ret = i2c_smbus_write_byte(st->client,
  47                                    LTC2497_ENABLE | address);
  48         if (ret)
  49                 dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
  50                         ERR_PTR(ret));
  51         return ret;
  52 }
  53
  54 static int ltc2497_probe(struct i2c_client *client,
  55                          const struct i2c_device_id *id)
  56 {
  57         struct iio_dev *indio_dev;
  58         struct ltc2497_driverdata *st;
  59         struct device *dev = &client->dev;
  60
  61         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
  62                                      I2C_FUNC_SMBUS_WRITE_BYTE))
  63                 return -EOPNOTSUPP;
  64
  65         indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
  66         if (!indio_dev)
  67                 return -ENOMEM;
  68
  69         st = iio_priv(indio_dev);
  70         i2c_set_clientdata(client, indio_dev);
  71         st->client = client;
  72         st->common_ddata.result_and_measure = ltc2497_result_and_measure;
  73
  74         return ltc2497core_probe(dev, indio_dev);
  75 }
  76
  77 static int ltc2497_remove(struct i2c_client *client)
  78 {
  79         struct iio_dev *indio_dev = i2c_get_clientdata(client);
  80
  81         ltc2497core_remove(indio_dev);
  82
  83         return 0;
  84 }
  85
  86 static const struct i2c_device_id ltc2497_id[] = {
  87         { "ltc2497", 0 },
  88         { }
  89 };
  90 MODULE_DEVICE_TABLE(i2c, ltc2497_id);
  91
  92 static const struct of_device_id ltc2497_of_match[] = {
  93         { .compatible = "lltc,ltc2497", },
  94         {},
  95 };
  96 MODULE_DEVICE_TABLE(of, ltc2497_of_match);
  97
  98 static struct i2c_driver ltc2497_driver = {
  99         .driver = {
 100                 .name = "ltc2497",
 101                 .of_match_table = ltc2497_of_match,
 102         },
 103         .probe = ltc2497_probe,
 104         .remove = ltc2497_remove,
 105         .id_table = ltc2497_id,
 106 };
 107 module_i2c_driver(ltc2497_driver);
 108
 109 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 110 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
 111 MODULE_LICENSE("GPL v2");