drivers/hwmon/iio_hwmon.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* Hwmon client for industrial I/O devices
0003  *
0004  * Copyright (c) 2011 Jonathan Cameron
0005  */
0006
0007 #include <linux/kernel.h>
0008 #include <linux/slab.h>
0009 #include <linux/module.h>
0010 #include <linux/err.h>
0011 #include <linux/platform_device.h>
0012 #include <linux/hwmon.h>
0013 #include <linux/of.h>
0014 #include <linux/hwmon-sysfs.h>
0015 #include <linux/iio/consumer.h>
0016 #include <linux/iio/types.h>
0017
0018 /**
0019  * struct iio_hwmon_state - device instance state
0020  * @channels:       filled with array of channels from iio
0021  * @num_channels:   number of channels in channels (saves counting twice)
0022  * @attr_group:     the group of attributes
0023  * @groups:     null terminated array of attribute groups
0024  * @attrs:      null terminated array of attribute pointers.
0025  */
0026 struct iio_hwmon_state {
0027     struct iio_channel *channels;
0028     int num_channels;
0029     struct attribute_group attr_group;
0030     const struct attribute_group *groups[2];
0031     struct attribute **attrs;
0032 };
0033
0034 /*
0035  * Assumes that IIO and hwmon operate in the same base units.
0036  * This is supposed to be true, but needs verification for
0037  * new channel types.
0038  */
0039 static ssize_t iio_hwmon_read_val(struct device *dev,
0040                   struct device_attribute *attr,
0041                   char *buf)
0042 {
0043     int result;
0044     int ret;
0045     struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
0046     struct iio_hwmon_state *state = dev_get_drvdata(dev);
0047     struct iio_channel *chan = &state->channels[sattr->index];
0048     enum iio_chan_type type;
0049
0050     ret = iio_read_channel_processed(chan, &result);
0051     if (ret < 0)
0052         return ret;
0053
0054     ret = iio_get_channel_type(chan, &type);
0055     if (ret < 0)
0056         return ret;
0057
0058     if (type == IIO_POWER)
0059         result *= 1000; /* mili-Watts to micro-Watts conversion */
0060
0061     return sprintf(buf, "%d\n", result);
0062 }
0063
0064 static int iio_hwmon_probe(struct platform_device *pdev)
0065 {
0066     struct device *dev = &pdev->dev;
0067     struct iio_hwmon_state *st;
0068     struct sensor_device_attribute *a;
0069     int ret, i;
0070     int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
0071     enum iio_chan_type type;
0072     struct iio_channel *channels;
0073     struct device *hwmon_dev;
0074     char *sname;
0075
0076     channels = devm_iio_channel_get_all(dev);
0077     if (IS_ERR(channels)) {
0078         if (PTR_ERR(channels) == -ENODEV)
0079             return -EPROBE_DEFER;
0080         return PTR_ERR(channels);
0081     }
0082
0083     st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
0084     if (st == NULL)
0085         return -ENOMEM;
0086
0087     st->channels = channels;
0088
0089     /* count how many attributes we have */
0090     while (st->channels[st->num_channels].indio_dev)
0091         st->num_channels++;
0092
0093     st->attrs = devm_kcalloc(dev,
0094                  st->num_channels + 1, sizeof(*st->attrs),
0095                  GFP_KERNEL);
0096     if (st->attrs == NULL)
0097         return -ENOMEM;
0098
0099     for (i = 0; i < st->num_channels; i++) {
0100         const char *prefix;
0101         int n;
0102
0103         a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
0104         if (a == NULL)
0105             return -ENOMEM;
0106
0107         sysfs_attr_init(&a->dev_attr.attr);
0108         ret = iio_get_channel_type(&st->channels[i], &type);
0109         if (ret < 0)
0110             return ret;
0111
0112         switch (type) {
0113         case IIO_VOLTAGE:
0114             n = in_i++;
0115             prefix = "in";
0116             break;
0117         case IIO_TEMP:
0118             n = temp_i++;
0119             prefix = "temp";
0120             break;
0121         case IIO_CURRENT:
0122             n = curr_i++;
0123             prefix = "curr";
0124             break;
0125         case IIO_POWER:
0126             n = power_i++;
0127             prefix = "power";
0128             break;
0129         case IIO_HUMIDITYRELATIVE:
0130             n = humidity_i++;
0131             prefix = "humidity";
0132             break;
0133         default:
0134             return -EINVAL;
0135         }
0136
0137         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
0138                                "%s%d_input",
0139                                prefix, n);
0140         if (a->dev_attr.attr.name == NULL)
0141             return -ENOMEM;
0142
0143         a->dev_attr.show = iio_hwmon_read_val;
0144         a->dev_attr.attr.mode = 0444;
0145         a->index = i;
0146         st->attrs[i] = &a->dev_attr.attr;
0147     }
0148
0149     st->attr_group.attrs = st->attrs;
0150     st->groups[0] = &st->attr_group;
0151
0152     if (dev->of_node) {
0153         sname = devm_kasprintf(dev, GFP_KERNEL, "%pOFn", dev->of_node);
0154         if (!sname)
0155             return -ENOMEM;
0156         strreplace(sname, '-', '_');
0157     } else {
0158         sname = "iio_hwmon";
0159     }
0160
0161     hwmon_dev = devm_hwmon_device_register_with_groups(dev, sname, st,
0162                                st->groups);
0163     return PTR_ERR_OR_ZERO(hwmon_dev);
0164 }
0165
0166 static const struct of_device_id iio_hwmon_of_match[] = {
0167     { .compatible = "iio-hwmon", },
0168     { }
0169 };
0170 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
0171
0172 static struct platform_driver iio_hwmon_driver = {
0173     .driver = {
0174         .name = "iio_hwmon",
0175         .of_match_table = iio_hwmon_of_match,
0176     },
0177     .probe = iio_hwmon_probe,
0178 };
0179
0180 module_platform_driver(iio_hwmon_driver);
0181
0182 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
0183 MODULE_DESCRIPTION("IIO to hwmon driver");
0184 MODULE_LICENSE("GPL v2");