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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                 return PTR_ERR(channels);
 78 
 79         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
 80         if (st == NULL) {
 81                 ret = -ENOMEM;
 82                 goto error_release_channels;
 83         }
 84 
 85         st->channels = channels;
 86 
 87         /* count how many attributes we have */
 88         while (st->channels[st->num_channels].indio_dev)
 89                 st->num_channels++;
 90 
 91         st->attrs = devm_kzalloc(dev,
 92                                  sizeof(*st->attrs) * (st->num_channels + 1),
 93                                  GFP_KERNEL);
 94         if (st->attrs == NULL) {
 95                 ret = -ENOMEM;
 96                 goto error_release_channels;
 97         }
 98 
 99         for (i = 0; i < st->num_channels; i++) {
100                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
101                 if (a == NULL) {
102                         ret = -ENOMEM;
103                         goto error_release_channels;
104                 }
105 
106                 sysfs_attr_init(&a->dev_attr.attr);
107                 ret = iio_get_channel_type(&st->channels[i], &type);
108                 if (ret < 0)
109                         goto error_release_channels;
110 
111                 switch (type) {
112                 case IIO_VOLTAGE:
113                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
114                                                           "in%d_input",
115                                                           in_i++);
116                         break;
117                 case IIO_TEMP:
118                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
119                                                           "temp%d_input",
120                                                           temp_i++);
121                         break;
122                 case IIO_CURRENT:
123                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
124                                                           "curr%d_input",
125                                                           curr_i++);
126                         break;
127                 case IIO_HUMIDITYRELATIVE:
128                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
129                                                           "humidity%d_input",
130                                                           humidity_i++);
131                         break;
132                 default:
133                         ret = -EINVAL;
134                         goto error_release_channels;
135                 }
136                 if (a->dev_attr.attr.name == NULL) {
137                         ret = -ENOMEM;
138                         goto error_release_channels;
139                 }
140                 a->dev_attr.show = iio_hwmon_read_val;
141                 a->dev_attr.attr.mode = S_IRUGO;
142                 a->index = i;
143                 st->attrs[i] = &a->dev_attr.attr;
144         }
145 
146         st->attr_group.attrs = st->attrs;
147         st->groups[0] = &st->attr_group;
148 
149         sname = devm_kstrdup(dev, name, GFP_KERNEL);
150         if (!sname) {
151                 ret = -ENOMEM;
152                 goto error_release_channels;
153         }
154 
155         strreplace(sname, '-', '_');
156         st->hwmon_dev = hwmon_device_register_with_groups(dev, sname, st,
157                                                           st->groups);
158         if (IS_ERR(st->hwmon_dev)) {
159                 ret = PTR_ERR(st->hwmon_dev);
160                 goto error_release_channels;
161         }
162         platform_set_drvdata(pdev, st);
163         return 0;
164 
165 error_release_channels:
166         iio_channel_release_all(channels);
167         return ret;
168 }
169 
170 static int iio_hwmon_remove(struct platform_device *pdev)
171 {
172         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
173 
174         hwmon_device_unregister(st->hwmon_dev);
175         iio_channel_release_all(st->channels);
176 
177         return 0;
178 }
179 
180 static const struct of_device_id iio_hwmon_of_match[] = {
181         { .compatible = "iio-hwmon", },
182         { }
183 };
184 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
185 
186 static struct platform_driver __refdata iio_hwmon_driver = {
187         .driver = {
188                 .name = "iio_hwmon",
189                 .of_match_table = iio_hwmon_of_match,
190         },
191         .probe = iio_hwmon_probe,
192         .remove = iio_hwmon_remove,
193 };
194 
195 module_platform_driver(iio_hwmon_driver);
196 
197 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
198 MODULE_DESCRIPTION("IIO to hwmon driver");
199 MODULE_LICENSE("GPL v2");
200 

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