drivers/staging/iio/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/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  * @hwmon_dev:          associated hwmon device
  25  * @attr_group: the group of attributes
  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 device *hwmon_dev;
  32         struct attribute_group attr_group;
  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  */
  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
  50         ret = iio_read_channel_processed(&state->channels[sattr->index],
  51                                         &result);
  52         if (ret < 0)
  53                 return ret;
  54
  55         return sprintf(buf, "%d\n", result);
  56 }
  57
  58 static ssize_t show_name(struct device *dev, struct device_attribute *attr,
  59                          char *buf)
  60 {
  61         return sprintf(buf, "iio_hwmon\n");
  62 }
  63
  64 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  65
  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;
  73         enum iio_chan_type type;
  74         struct iio_channel *channels;
  75
  76         channels = iio_channel_get_all(dev);
  77         if (IS_ERR(channels))
  78                 return PTR_ERR(channels);
  79
  80         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  81         if (st == NULL)
  82                 return -ENOMEM;
  83
  84         st->channels = channels;
  85
  86         /* count how many attributes we have */
  87         while (st->channels[st->num_channels].indio_dev)
  88                 st->num_channels++;
  89
  90         st->attrs = devm_kzalloc(dev,
  91                                  sizeof(*st->attrs) * (st->num_channels + 2),
  92                                  GFP_KERNEL);
  93         if (st->attrs == NULL) {
  94                 ret = -ENOMEM;
  95                 goto error_release_channels;
  96         }
  97
  98         for (i = 0; i < st->num_channels; i++) {
  99                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 100                 if (a == NULL) {
 101                         ret = -ENOMEM;
 102                         goto error_release_channels;
 103                 }
 104
 105                 sysfs_attr_init(&a->dev_attr.attr);
 106                 ret = iio_get_channel_type(&st->channels[i], &type);
 107                 if (ret < 0)
 108                         goto error_release_channels;
 109
 110                 switch (type) {
 111                 case IIO_VOLTAGE:
 112                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 113                                                           "in%d_input",
 114                                                           in_i++);
 115                         break;
 116                 case IIO_TEMP:
 117                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 118                                                           "temp%d_input",
 119                                                           temp_i++);
 120                         break;
 121                 case IIO_CURRENT:
 122                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 123                                                           "curr%d_input",
 124                                                           curr_i++);
 125                         break;
 126                 default:
 127                         ret = -EINVAL;
 128                         goto error_release_channels;
 129                 }
 130                 if (a->dev_attr.attr.name == NULL) {
 131                         ret = -ENOMEM;
 132                         goto error_release_channels;
 133                 }
 134                 a->dev_attr.show = iio_hwmon_read_val;
 135                 a->dev_attr.attr.mode = S_IRUGO;
 136                 a->index = i;
 137                 st->attrs[i] = &a->dev_attr.attr;
 138         }
 139         st->attrs[st->num_channels] = &dev_attr_name.attr;
 140         st->attr_group.attrs = st->attrs;
 141         platform_set_drvdata(pdev, st);
 142         ret = sysfs_create_group(&dev->kobj, &st->attr_group);
 143         if (ret < 0)
 144                 goto error_release_channels;
 145
 146         st->hwmon_dev = hwmon_device_register(dev);
 147         if (IS_ERR(st->hwmon_dev)) {
 148                 ret = PTR_ERR(st->hwmon_dev);
 149                 goto error_remove_group;
 150         }
 151         return 0;
 152
 153 error_remove_group:
 154         sysfs_remove_group(&dev->kobj, &st->attr_group);
 155 error_release_channels:
 156         iio_channel_release_all(st->channels);
 157         return ret;
 158 }
 159
 160 static int iio_hwmon_remove(struct platform_device *pdev)
 161 {
 162         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 163
 164         hwmon_device_unregister(st->hwmon_dev);
 165         sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 166         iio_channel_release_all(st->channels);
 167
 168         return 0;
 169 }
 170
 171 static struct of_device_id iio_hwmon_of_match[] = {
 172         { .compatible = "iio-hwmon", },
 173         { }
 174 };
 175
 176 static struct platform_driver __refdata iio_hwmon_driver = {
 177         .driver = {
 178                 .name = "iio_hwmon",
 179                 .owner = THIS_MODULE,
 180                 .of_match_table = iio_hwmon_of_match,
 181         },
 182         .probe = iio_hwmon_probe,
 183         .remove = iio_hwmon_remove,
 184 };
 185
 186 module_platform_driver(iio_hwmon_driver);
 187
 188 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 189 MODULE_DESCRIPTION("IIO to hwmon driver");
 190 MODULE_LICENSE("GPL v2");