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         struct attribute **attrs;
  35 };
  36
  37 /*
  38  * Assumes that IIO and hwmon operate in the same base units.
  39  * This is supposed to be true, but needs verification for
  40  * new channel types.
  41  */
  42 static ssize_t iio_hwmon_read_val(struct device *dev,
  43                                   struct device_attribute *attr,
  44                                   char *buf)
  45 {
  46         int result;
  47         int ret;
  48         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  49         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  50
  51         ret = iio_read_channel_processed(&state->channels[sattr->index],
  52                                         &result);
  53         if (ret < 0)
  54                 return ret;
  55
  56         return sprintf(buf, "%d\n", result);
  57 }
  58
  59 static ssize_t show_name(struct device *dev, struct device_attribute *attr,
  60                          char *buf)
  61 {
  62         const char *name = "iio_hwmon";
  63
  64         if (dev->of_node && dev->of_node->name)
  65                 name = dev->of_node->name;
  66
  67         return sprintf(buf, "%s\n", name);
  68 }
  69
  70 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  71
  72 static int iio_hwmon_probe(struct platform_device *pdev)
  73 {
  74         struct device *dev = &pdev->dev;
  75         struct iio_hwmon_state *st;
  76         struct sensor_device_attribute *a;
  77         int ret, i;
  78         int in_i = 1, temp_i = 1, curr_i = 1;
  79         enum iio_chan_type type;
  80         struct iio_channel *channels;
  81
  82         channels = iio_channel_get_all(dev);
  83         if (IS_ERR(channels))
  84                 return PTR_ERR(channels);
  85
  86         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  87         if (st == NULL)
  88                 return -ENOMEM;
  89
  90         st->channels = channels;
  91
  92         /* count how many attributes we have */
  93         while (st->channels[st->num_channels].indio_dev)
  94                 st->num_channels++;
  95
  96         st->attrs = devm_kzalloc(dev,
  97                                  sizeof(*st->attrs) * (st->num_channels + 2),
  98                                  GFP_KERNEL);
  99         if (st->attrs == NULL) {
 100                 ret = -ENOMEM;
 101                 goto error_release_channels;
 102         }
 103
 104         for (i = 0; i < st->num_channels; i++) {
 105                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 106                 if (a == NULL) {
 107                         ret = -ENOMEM;
 108                         goto error_release_channels;
 109                 }
 110
 111                 sysfs_attr_init(&a->dev_attr.attr);
 112                 ret = iio_get_channel_type(&st->channels[i], &type);
 113                 if (ret < 0)
 114                         goto error_release_channels;
 115
 116                 switch (type) {
 117                 case IIO_VOLTAGE:
 118                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 119                                                           "in%d_input",
 120                                                           in_i++);
 121                         break;
 122                 case IIO_TEMP:
 123                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 124                                                           "temp%d_input",
 125                                                           temp_i++);
 126                         break;
 127                 case IIO_CURRENT:
 128                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 129                                                           "curr%d_input",
 130                                                           curr_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         st->attrs[st->num_channels] = &dev_attr_name.attr;
 146         st->attr_group.attrs = st->attrs;
 147         platform_set_drvdata(pdev, st);
 148         ret = sysfs_create_group(&dev->kobj, &st->attr_group);
 149         if (ret < 0)
 150                 goto error_release_channels;
 151
 152         st->hwmon_dev = hwmon_device_register(dev);
 153         if (IS_ERR(st->hwmon_dev)) {
 154                 ret = PTR_ERR(st->hwmon_dev);
 155                 goto error_remove_group;
 156         }
 157         return 0;
 158
 159 error_remove_group:
 160         sysfs_remove_group(&dev->kobj, &st->attr_group);
 161 error_release_channels:
 162         iio_channel_release_all(st->channels);
 163         return ret;
 164 }
 165
 166 static int iio_hwmon_remove(struct platform_device *pdev)
 167 {
 168         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 169
 170         hwmon_device_unregister(st->hwmon_dev);
 171         sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 172         iio_channel_release_all(st->channels);
 173
 174         return 0;
 175 }
 176
 177 static struct of_device_id iio_hwmon_of_match[] = {
 178         { .compatible = "iio-hwmon", },
 179         { }
 180 };
 181
 182 static struct platform_driver __refdata iio_hwmon_driver = {
 183         .driver = {
 184                 .name = "iio_hwmon",
 185                 .owner = THIS_MODULE,
 186                 .of_match_table = iio_hwmon_of_match,
 187         },
 188         .probe = iio_hwmon_probe,
 189         .remove = iio_hwmon_remove,
 190 };
 191
 192 module_platform_driver(iio_hwmon_driver);
 193
 194 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 195 MODULE_DESCRIPTION("IIO to hwmon driver");
 196 MODULE_LICENSE("GPL v2");