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Linux/drivers/hwmon/iio_hwmon.c

  1 /* Hwmon client for industrial I/O devices
  2  *
  3  * Copyright (c) 2011 Jonathan Cameron
  4  *
  5  * This program is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 as published by
  7  * the Free Software Foundation.
  8  */
  9 
 10 #include <linux/kernel.h>
 11 #include <linux/slab.h>
 12 #include <linux/module.h>
 13 #include <linux/err.h>
 14 #include <linux/platform_device.h>
 15 #include <linux/hwmon.h>
 16 #include <linux/of.h>
 17 #include <linux/hwmon-sysfs.h>
 18 #include <linux/iio/consumer.h>
 19 #include <linux/iio/types.h>
 20 
 21 /**
 22  * struct iio_hwmon_state - device instance state
 23  * @channels:           filled with array of channels from iio
 24  * @num_channels:       number of channels in channels (saves counting twice)
 25  * @hwmon_dev:          associated hwmon device
 26  * @attr_group: the group of attributes
 27  * @attrs:              null terminated array of attribute pointers.
 28  */
 29 struct iio_hwmon_state {
 30         struct iio_channel *channels;
 31         int num_channels;
 32         struct device *hwmon_dev;
 33         struct attribute_group attr_group;
 34         const struct attribute_group *groups[2];
 35         struct attribute **attrs;
 36 };
 37 
 38 /*
 39  * Assumes that IIO and hwmon operate in the same base units.
 40  * This is supposed to be true, but needs verification for
 41  * new channel types.
 42  */
 43 static ssize_t iio_hwmon_read_val(struct device *dev,
 44                                   struct device_attribute *attr,
 45                                   char *buf)
 46 {
 47         int result;
 48         int ret;
 49         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
 50         struct iio_hwmon_state *state = dev_get_drvdata(dev);
 51 
 52         ret = iio_read_channel_processed(&state->channels[sattr->index],
 53                                         &result);
 54         if (ret < 0)
 55                 return ret;
 56 
 57         return sprintf(buf, "%d\n", result);
 58 }
 59 
 60 static int iio_hwmon_probe(struct platform_device *pdev)
 61 {
 62         struct device *dev = &pdev->dev;
 63         struct iio_hwmon_state *st;
 64         struct sensor_device_attribute *a;
 65         int ret, i;
 66         int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1;
 67         enum iio_chan_type type;
 68         struct iio_channel *channels;
 69         const char *name = "iio_hwmon";
 70         char *sname;
 71 
 72         if (dev->of_node && dev->of_node->name)
 73                 name = dev->of_node->name;
 74 
 75         channels = iio_channel_get_all(dev);
 76         if (IS_ERR(channels)) {
 77                 if (PTR_ERR(channels) == -ENODEV)
 78                         return -EPROBE_DEFER;
 79                 return PTR_ERR(channels);
 80         }
 81 
 82         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
 83         if (st == NULL) {
 84                 ret = -ENOMEM;
 85                 goto error_release_channels;
 86         }
 87 
 88         st->channels = channels;
 89 
 90         /* count how many attributes we have */
 91         while (st->channels[st->num_channels].indio_dev)
 92                 st->num_channels++;
 93 
 94         st->attrs = devm_kzalloc(dev,
 95                                  sizeof(*st->attrs) * (st->num_channels + 1),
 96                                  GFP_KERNEL);
 97         if (st->attrs == NULL) {
 98                 ret = -ENOMEM;
 99                 goto error_release_channels;
100         }
101 
102         for (i = 0; i < st->num_channels; i++) {
103                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
104                 if (a == NULL) {
105                         ret = -ENOMEM;
106                         goto error_release_channels;
107                 }
108 
109                 sysfs_attr_init(&a->dev_attr.attr);
110                 ret = iio_get_channel_type(&st->channels[i], &type);
111                 if (ret < 0)
112                         goto error_release_channels;
113 
114                 switch (type) {
115                 case IIO_VOLTAGE:
116                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
117                                                                "in%d_input",
118                                                                in_i++);
119                         break;
120                 case IIO_TEMP:
121                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
122                                                                "temp%d_input",
123                                                                temp_i++);
124                         break;
125                 case IIO_CURRENT:
126                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
127                                                                "curr%d_input",
128                                                                curr_i++);
129                         break;
130                 case IIO_HUMIDITYRELATIVE:
131                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
132                                                                "humidity%d_input",
133                                                                humidity_i++);
134                         break;
135                 default:
136                         ret = -EINVAL;
137                         goto error_release_channels;
138                 }
139                 if (a->dev_attr.attr.name == NULL) {
140                         ret = -ENOMEM;
141                         goto error_release_channels;
142                 }
143                 a->dev_attr.show = iio_hwmon_read_val;
144                 a->dev_attr.attr.mode = S_IRUGO;
145                 a->index = i;
146                 st->attrs[i] = &a->dev_attr.attr;
147         }
148 
149         st->attr_group.attrs = st->attrs;
150         st->groups[0] = &st->attr_group;
151 
152         sname = devm_kstrdup(dev, name, GFP_KERNEL);
153         if (!sname) {
154                 ret = -ENOMEM;
155                 goto error_release_channels;
156         }
157 
158         strreplace(sname, '-', '_');
159         st->hwmon_dev = hwmon_device_register_with_groups(dev, sname, st,
160                                                           st->groups);
161         if (IS_ERR(st->hwmon_dev)) {
162                 ret = PTR_ERR(st->hwmon_dev);
163                 goto error_release_channels;
164         }
165         platform_set_drvdata(pdev, st);
166         return 0;
167 
168 error_release_channels:
169         iio_channel_release_all(channels);
170         return ret;
171 }
172 
173 static int iio_hwmon_remove(struct platform_device *pdev)
174 {
175         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
176 
177         hwmon_device_unregister(st->hwmon_dev);
178         iio_channel_release_all(st->channels);
179 
180         return 0;
181 }
182 
183 static const struct of_device_id iio_hwmon_of_match[] = {
184         { .compatible = "iio-hwmon", },
185         { }
186 };
187 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
188 
189 static struct platform_driver __refdata iio_hwmon_driver = {
190         .driver = {
191                 .name = "iio_hwmon",
192                 .of_match_table = iio_hwmon_of_match,
193         },
194         .probe = iio_hwmon_probe,
195         .remove = iio_hwmon_remove,
196 };
197 
198 module_platform_driver(iio_hwmon_driver);
199 
200 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
201 MODULE_DESCRIPTION("IIO to hwmon driver");
202 MODULE_LICENSE("GPL v2");
203 

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