xref: /openbmc/linux/drivers/hwmon/iio_hwmon.c (revision 1c999af5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Hwmon client for industrial I/O devices
3  *
4  * Copyright (c) 2011 Jonathan Cameron
5  */
6 
7 #include <linux/kernel.h>
8 #include <linux/slab.h>
9 #include <linux/mod_devicetable.h>
10 #include <linux/module.h>
11 #include <linux/err.h>
12 #include <linux/platform_device.h>
13 #include <linux/property.h>
14 
15 #include <linux/hwmon.h>
16 #include <linux/hwmon-sysfs.h>
17 #include <linux/iio/consumer.h>
18 #include <linux/iio/types.h>
19 
20 /**
21  * struct iio_hwmon_state - device instance state
22  * @channels:		filled with array of channels from iio
23  * @num_channels:	number of channels in channels (saves counting twice)
24  * @attr_group:		the group of attributes
25  * @groups:		null terminated array of attribute groups
26  * @attrs:		null terminated array of attribute pointers.
27  */
28 struct iio_hwmon_state {
29 	struct iio_channel *channels;
30 	int num_channels;
31 	struct attribute_group attr_group;
32 	const struct attribute_group *groups[2];
33 	struct attribute **attrs;
34 };
35 
36 /*
37  * Assumes that IIO and hwmon operate in the same base units.
38  * This is supposed to be true, but needs verification for
39  * new channel types.
40  */
iio_hwmon_read_val(struct device * dev,struct device_attribute * attr,char * buf)41 static ssize_t iio_hwmon_read_val(struct device *dev,
42 				  struct device_attribute *attr,
43 				  char *buf)
44 {
45 	int result;
46 	int ret;
47 	struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
48 	struct iio_hwmon_state *state = dev_get_drvdata(dev);
49 	struct iio_channel *chan = &state->channels[sattr->index];
50 	enum iio_chan_type type;
51 
52 	ret = iio_read_channel_processed(chan, &result);
53 	if (ret < 0)
54 		return ret;
55 
56 	ret = iio_get_channel_type(chan, &type);
57 	if (ret < 0)
58 		return ret;
59 
60 	if (type == IIO_POWER)
61 		result *= 1000; /* mili-Watts to micro-Watts conversion */
62 
63 	return sprintf(buf, "%d\n", result);
64 }
65 
iio_hwmon_probe(struct platform_device * pdev)66 static int iio_hwmon_probe(struct platform_device *pdev)
67 {
68 	struct device *dev = &pdev->dev;
69 	struct iio_hwmon_state *st;
70 	struct sensor_device_attribute *a;
71 	int ret, i;
72 	int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
73 	enum iio_chan_type type;
74 	struct iio_channel *channels;
75 	struct device *hwmon_dev;
76 	char *sname;
77 
78 	channels = devm_iio_channel_get_all(dev);
79 	if (IS_ERR(channels)) {
80 		ret = PTR_ERR(channels);
81 		if (ret == -ENODEV)
82 			ret = -EPROBE_DEFER;
83 		return dev_err_probe(dev, ret,
84 				     "Failed to get channels\n");
85 	}
86 
87 	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
88 	if (st == NULL)
89 		return -ENOMEM;
90 
91 	st->channels = channels;
92 
93 	/* count how many attributes we have */
94 	while (st->channels[st->num_channels].indio_dev)
95 		st->num_channels++;
96 
97 	st->attrs = devm_kcalloc(dev,
98 				 st->num_channels + 1, sizeof(*st->attrs),
99 				 GFP_KERNEL);
100 	if (st->attrs == NULL)
101 		return -ENOMEM;
102 
103 	for (i = 0; i < st->num_channels; i++) {
104 		const char *prefix;
105 		int n;
106 
107 		a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
108 		if (a == NULL)
109 			return -ENOMEM;
110 
111 		sysfs_attr_init(&a->dev_attr.attr);
112 		ret = iio_get_channel_type(&st->channels[i], &type);
113 		if (ret < 0)
114 			return ret;
115 
116 		switch (type) {
117 		case IIO_VOLTAGE:
118 			n = in_i++;
119 			prefix = "in";
120 			break;
121 		case IIO_TEMP:
122 			n = temp_i++;
123 			prefix = "temp";
124 			break;
125 		case IIO_CURRENT:
126 			n = curr_i++;
127 			prefix = "curr";
128 			break;
129 		case IIO_POWER:
130 			n = power_i++;
131 			prefix = "power";
132 			break;
133 		case IIO_HUMIDITYRELATIVE:
134 			n = humidity_i++;
135 			prefix = "humidity";
136 			break;
137 		default:
138 			return -EINVAL;
139 		}
140 
141 		a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
142 						       "%s%d_input",
143 						       prefix, n);
144 		if (a->dev_attr.attr.name == NULL)
145 			return -ENOMEM;
146 
147 		a->dev_attr.show = iio_hwmon_read_val;
148 		a->dev_attr.attr.mode = 0444;
149 		a->index = i;
150 		st->attrs[i] = &a->dev_attr.attr;
151 	}
152 
153 	st->attr_group.attrs = st->attrs;
154 	st->groups[0] = &st->attr_group;
155 
156 	if (dev_fwnode(dev)) {
157 		sname = devm_kasprintf(dev, GFP_KERNEL, "%pfwP", dev_fwnode(dev));
158 		if (!sname)
159 			return -ENOMEM;
160 		strreplace(sname, '-', '_');
161 	} else {
162 		sname = "iio_hwmon";
163 	}
164 
165 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, sname, st,
166 							   st->groups);
167 	return PTR_ERR_OR_ZERO(hwmon_dev);
168 }
169 
170 static const struct of_device_id iio_hwmon_of_match[] = {
171 	{ .compatible = "iio-hwmon", },
172 	{ }
173 };
174 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
175 
176 static struct platform_driver iio_hwmon_driver = {
177 	.driver = {
178 		.name = "iio_hwmon",
179 		.of_match_table = iio_hwmon_of_match,
180 	},
181 	.probe = iio_hwmon_probe,
182 };
183 
184 module_platform_driver(iio_hwmon_driver);
185 
186 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
187 MODULE_DESCRIPTION("IIO to hwmon driver");
188 MODULE_LICENSE("GPL v2");
189