industrialio-adc.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Helpers for parsing common ADC information from a firmware node.
 4 *
 5 * Copyright (c) 2025 Matti Vaittinen <mazziesaccount@gmail.com>
 6 */
 7
 8#include <linux/device.h>
 9#include <linux/errno.h>
10#include <linux/export.h>
11#include <linux/module.h>
12#include <linux/property.h>
13#include <linux/types.h>
14
15#include <linux/iio/adc-helpers.h>
16#include <linux/iio/iio.h>
17
18/**
19 * devm_iio_adc_device_alloc_chaninfo_se - allocate and fill iio_chan_spec for ADC
20 *
21 * Scan the device node for single-ended ADC channel information. Channel ID is
22 * expected to be found from the "reg" property. Allocate and populate the
23 * iio_chan_spec structure corresponding to channels that are found. The memory
24 * for iio_chan_spec structure will be freed upon device detach.
25 *
26 * @dev:		Pointer to the ADC device.
27 * @template:		Template iio_chan_spec from which the fields of all
28 *			found and allocated channels are initialized.
29 * @max_chan_id:	Maximum value of a channel ID. Use negative value if no
30 *			checking is required.
31 * @cs:			Location where pointer to allocated iio_chan_spec
32 *			should be stored.
33 *
34 * Return:	Number of found channels on success. Negative value to indicate
35 *		failure. Specifically, -ENOENT if no channel nodes were found.
36 */
37int devm_iio_adc_device_alloc_chaninfo_se(struct device *dev,
38					  const struct iio_chan_spec *template,
39					  int max_chan_id,
40					  struct iio_chan_spec **cs)
41{
42	struct iio_chan_spec *chan_array, *chan;
43	int num_chan, ret;
44
45	num_chan = iio_adc_device_num_channels(dev);
46	if (num_chan < 0)
47		return num_chan;
48
49	if (!num_chan)
50		return -ENOENT;
51
52	chan_array = devm_kcalloc(dev, num_chan, sizeof(*chan_array),
53				  GFP_KERNEL);
54	if (!chan_array)
55		return -ENOMEM;
56
57	chan = &chan_array[0];
58
59	device_for_each_named_child_node_scoped(dev, child, "channel") {
60		u32 ch;
61
62		ret = fwnode_property_read_u32(child, "reg", &ch);
63		if (ret)
64			return ret;
65
66		if (max_chan_id >= 0 && ch > max_chan_id)
67			return -ERANGE;
68
69		*chan = *template;
70		chan->channel = ch;
71		chan++;
72	}
73
74	*cs = chan_array;
75
76	return num_chan;
77}
78EXPORT_SYMBOL_NS_GPL(devm_iio_adc_device_alloc_chaninfo_se, "IIO_DRIVER");
79
80MODULE_LICENSE("GPL");
81MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
82MODULE_DESCRIPTION("IIO ADC fwnode parsing helpers");