iio_hwmon.c
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/* Hwmon client for industrial I/O devices
*
* Copyright (c) 2011 Jonathan Cameron
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/hwmon.h>
#include <linux/of.h>
#include <linux/hwmon-sysfs.h>
#include <linux/iio/consumer.h>
#include <linux/iio/types.h>
/**
* struct iio_hwmon_state - device instance state
* @channels: filled with array of channels from iio
* @num_channels: number of channels in channels (saves counting twice)
* @hwmon_dev: associated hwmon device
* @attr_group: the group of attributes
* @attrs: null terminated array of attribute pointers.
*/
struct iio_hwmon_state {
struct iio_channel *channels;
int num_channels;
struct device *hwmon_dev;
struct attribute_group attr_group;
struct attribute **attrs;
};
/*
* Assumes that IIO and hwmon operate in the same base units.
* This is supposed to be true, but needs verification for
* new channel types.
*/
static ssize_t iio_hwmon_read_val(struct device *dev,
struct device_attribute *attr,
char *buf)
{
int result;
int ret;
struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
struct iio_hwmon_state *state = dev_get_drvdata(dev);
ret = iio_read_channel_processed(&state->channels[sattr->index],
&result);
if (ret < 0)
return ret;
return sprintf(buf, "%d\n", result);
}
static ssize_t show_name(struct device *dev, struct device_attribute *attr,
char *buf)
{
const char *name = "iio_hwmon";
if (dev->of_node && dev->of_node->name)
name = dev->of_node->name;
return sprintf(buf, "%s\n", name);
}
static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
static int iio_hwmon_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct iio_hwmon_state *st;
struct sensor_device_attribute *a;
int ret, i;
int in_i = 1, temp_i = 1, curr_i = 1;
enum iio_chan_type type;
struct iio_channel *channels;
channels = iio_channel_get_all(dev);
if (IS_ERR(channels))
return PTR_ERR(channels);
st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
if (st == NULL) {
ret = -ENOMEM;
goto error_release_channels;
}
st->channels = channels;
/* count how many attributes we have */
while (st->channels[st->num_channels].indio_dev)
st->num_channels++;
st->attrs = devm_kzalloc(dev,
sizeof(*st->attrs) * (st->num_channels + 2),
GFP_KERNEL);
if (st->attrs == NULL) {
ret = -ENOMEM;
goto error_release_channels;
}
for (i = 0; i < st->num_channels; i++) {
a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
if (a == NULL) {
ret = -ENOMEM;
goto error_release_channels;
}
sysfs_attr_init(&a->dev_attr.attr);
ret = iio_get_channel_type(&st->channels[i], &type);
if (ret < 0)
goto error_release_channels;
switch (type) {
case IIO_VOLTAGE:
a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
"in%d_input",
in_i++);
break;
case IIO_TEMP:
a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
"temp%d_input",
temp_i++);
break;
case IIO_CURRENT:
a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
"curr%d_input",
curr_i++);
break;
default:
ret = -EINVAL;
goto error_release_channels;
}
if (a->dev_attr.attr.name == NULL) {
ret = -ENOMEM;
goto error_release_channels;
}
a->dev_attr.show = iio_hwmon_read_val;
a->dev_attr.attr.mode = S_IRUGO;
a->index = i;
st->attrs[i] = &a->dev_attr.attr;
}
st->attrs[st->num_channels] = &dev_attr_name.attr;
st->attr_group.attrs = st->attrs;
platform_set_drvdata(pdev, st);
ret = sysfs_create_group(&dev->kobj, &st->attr_group);
if (ret < 0)
goto error_release_channels;
st->hwmon_dev = hwmon_device_register(dev);
if (IS_ERR(st->hwmon_dev)) {
ret = PTR_ERR(st->hwmon_dev);
goto error_remove_group;
}
return 0;
error_remove_group:
sysfs_remove_group(&dev->kobj, &st->attr_group);
error_release_channels:
iio_channel_release_all(channels);
return ret;
}
static int iio_hwmon_remove(struct platform_device *pdev)
{
struct iio_hwmon_state *st = platform_get_drvdata(pdev);
hwmon_device_unregister(st->hwmon_dev);
sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
iio_channel_release_all(st->channels);
return 0;
}
static struct of_device_id iio_hwmon_of_match[] = {
{ .compatible = "iio-hwmon", },
{ }
};
MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
static struct platform_driver __refdata iio_hwmon_driver = {
.driver = {
.name = "iio_hwmon",
.owner = THIS_MODULE,
.of_match_table = iio_hwmon_of_match,
},
.probe = iio_hwmon_probe,
.remove = iio_hwmon_remove,
};
module_platform_driver(iio_hwmon_driver);
MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("IIO to hwmon driver");
MODULE_LICENSE("GPL v2");