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 void iio_hwmon_free_attrs(struct iio_hwmon_state *st)
  59 {
  60         int i;
  61         struct sensor_device_attribute *a;
  62         for (i = 0; i < st->num_channels; i++)
  63                 if (st->attrs[i]) {
  64                         a = to_sensor_dev_attr(
  65                                 container_of(st->attrs[i],
  66                                              struct device_attribute,
  67                                              attr));
  68                         kfree(a);
  69                 }
  70 }
  71
  72 static int __devinit iio_hwmon_probe(struct platform_device *pdev)
  73 {
  74         struct iio_hwmon_state *st;
  75         struct sensor_device_attribute *a;
  76         int ret, i;
  77         int in_i = 1, temp_i = 1, curr_i = 1;
  78         enum iio_chan_type type;
  79
  80         st = kzalloc(sizeof(*st), GFP_KERNEL);
  81         if (st == NULL) {
  82                 ret = -ENOMEM;
  83                 goto error_ret;
  84         }
  85
  86         st->channels = iio_channel_get_all(dev_name(&pdev->dev));
  87         if (IS_ERR(st->channels)) {
  88                 ret = PTR_ERR(st->channels);
  89                 goto error_free_state;
  90         }
  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 = kzalloc(sizeof(st->attrs) * (st->num_channels + 1),
  97                             GFP_KERNEL);
  98         if (st->attrs == NULL) {
  99                 ret = -ENOMEM;
 100                 goto error_release_channels;
 101         }
 102         for (i = 0; i < st->num_channels; i++) {
 103                 a = kzalloc(sizeof(*a), GFP_KERNEL);
 104                 if (a == NULL) {
 105                         ret = -ENOMEM;
 106                         goto error_free_attrs;
 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                         kfree(a);
 113                         goto error_free_attrs;
 114                 }
 115                 switch (type) {
 116                 case IIO_VOLTAGE:
 117                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 118                                                           "in%d_input",
 119                                                           in_i++);
 120                         break;
 121                 case IIO_TEMP:
 122                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 123                                                           "temp%d_input",
 124                                                           temp_i++);
 125                         break;
 126                 case IIO_CURRENT:
 127                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 128                                                           "curr%d_input",
 129                                                           curr_i++);
 130                         break;
 131                 default:
 132                         ret = -EINVAL;
 133                         kfree(a);
 134                         goto error_free_attrs;
 135                 }
 136                 if (a->dev_attr.attr.name == NULL) {
 137                         kfree(a);
 138                         ret = -ENOMEM;
 139                         goto error_free_attrs;
 140                 }
 141                 a->dev_attr.show = iio_hwmon_read_val;
 142                 a->dev_attr.attr.mode = S_IRUGO;
 143                 a->index = i;
 144                 st->attrs[i] = &a->dev_attr.attr;
 145         }
 146
 147         st->attr_group.attrs = st->attrs;
 148         platform_set_drvdata(pdev, st);
 149         ret = sysfs_create_group(&pdev->dev.kobj, &st->attr_group);
 150         if (ret < 0)
 151                 goto error_free_attrs;
 152
 153         st->hwmon_dev = hwmon_device_register(&pdev->dev);
 154         if (IS_ERR(st->hwmon_dev)) {
 155                 ret = PTR_ERR(st->hwmon_dev);
 156                 goto error_remove_group;
 157         }
 158         return 0;
 159
 160 error_remove_group:
 161         sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 162 error_free_attrs:
 163         iio_hwmon_free_attrs(st);
 164         kfree(st->attrs);
 165 error_release_channels:
 166         iio_channel_release_all(st->channels);
 167 error_free_state:
 168         kfree(st);
 169 error_ret:
 170         return ret;
 171 }
 172
 173 static int __devexit 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         sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 179         iio_hwmon_free_attrs(st);
 180         kfree(st->attrs);
 181         iio_channel_release_all(st->channels);
 182
 183         return 0;
 184 }
 185
 186 static struct platform_driver __refdata iio_hwmon_driver = {
 187         .driver = {
 188                 .name = "iio_hwmon",
 189                 .owner = THIS_MODULE,
 190         },
 191         .probe = iio_hwmon_probe,
 192         .remove = __devexit_p(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");