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         long result;
  46         int val, ret, scaleint, scalepart;
  47         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  48         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  49
  50         /*
  51          * No locking between this pair, so theoretically possible
  52          * the scale has changed.
  53          */
  54         ret = iio_read_channel_raw(&state->channels[sattr->index],
  55                                       &val);
  56         if (ret < 0)
  57                 return ret;
  58
  59         ret = iio_read_channel_scale(&state->channels[sattr->index],
  60                                         &scaleint, &scalepart);
  61         if (ret < 0)
  62                 return ret;
  63         switch (ret) {
  64         case IIO_VAL_INT:
  65                 result = val * scaleint;
  66                 break;
  67         case IIO_VAL_INT_PLUS_MICRO:
  68                 result = (s64)val * (s64)scaleint +
  69                         div_s64((s64)val * (s64)scalepart, 1000000LL);
  70                 break;
  71         case IIO_VAL_INT_PLUS_NANO:
  72                 result = (s64)val * (s64)scaleint +
  73                         div_s64((s64)val * (s64)scalepart, 1000000000LL);
  74                 break;
  75         default:
  76                 return -EINVAL;
  77         }
  78         return sprintf(buf, "%ld\n", result);
  79 }
  80
  81 static void iio_hwmon_free_attrs(struct iio_hwmon_state *st)
  82 {
  83         int i;
  84         struct sensor_device_attribute *a;
  85         for (i = 0; i < st->num_channels; i++)
  86                 if (st->attrs[i]) {
  87                         a = to_sensor_dev_attr(
  88                                 container_of(st->attrs[i],
  89                                              struct device_attribute,
  90                                              attr));
  91                         kfree(a);
  92                 }
  93 }
  94
  95 static int __devinit iio_hwmon_probe(struct platform_device *pdev)
  96 {
  97         struct iio_hwmon_state *st;
  98         struct sensor_device_attribute *a;
  99         int ret, i;
 100         int in_i = 1, temp_i = 1, curr_i = 1;
 101         enum iio_chan_type type;
 102
 103         st = kzalloc(sizeof(*st), GFP_KERNEL);
 104         if (st == NULL) {
 105                 ret = -ENOMEM;
 106                 goto error_ret;
 107         }
 108
 109         st->channels = iio_channel_get_all(dev_name(&pdev->dev));
 110         if (IS_ERR(st->channels)) {
 111                 ret = PTR_ERR(st->channels);
 112                 goto error_free_state;
 113         }
 114
 115         /* count how many attributes we have */
 116         while (st->channels[st->num_channels].indio_dev)
 117                 st->num_channels++;
 118
 119         st->attrs = kzalloc(sizeof(st->attrs) * (st->num_channels + 1),
 120                             GFP_KERNEL);
 121         if (st->attrs == NULL) {
 122                 ret = -ENOMEM;
 123                 goto error_release_channels;
 124         }
 125         for (i = 0; i < st->num_channels; i++) {
 126                 a = kzalloc(sizeof(*a), GFP_KERNEL);
 127                 if (a == NULL) {
 128                         ret = -ENOMEM;
 129                         goto error_free_attrs;
 130                 }
 131
 132                 sysfs_attr_init(&a->dev_attr.attr);
 133                 ret = iio_get_channel_type(&st->channels[i], &type);
 134                 if (ret < 0) {
 135                         kfree(a);
 136                         goto error_free_attrs;
 137                 }
 138                 switch (type) {
 139                 case IIO_VOLTAGE:
 140                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 141                                                           "in%d_input",
 142                                                           in_i++);
 143                         break;
 144                 case IIO_TEMP:
 145                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 146                                                           "temp%d_input",
 147                                                           temp_i++);
 148                         break;
 149                 case IIO_CURRENT:
 150                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 151                                                           "curr%d_input",
 152                                                           curr_i++);
 153                         break;
 154                 default:
 155                         ret = -EINVAL;
 156                         kfree(a);
 157                         goto error_free_attrs;
 158                 }
 159                 if (a->dev_attr.attr.name == NULL) {
 160                         kfree(a);
 161                         ret = -ENOMEM;
 162                         goto error_free_attrs;
 163                 }
 164                 a->dev_attr.show = iio_hwmon_read_val;
 165                 a->dev_attr.attr.mode = S_IRUGO;
 166                 a->index = i;
 167                 st->attrs[i] = &a->dev_attr.attr;
 168         }
 169
 170         st->attr_group.attrs = st->attrs;
 171         platform_set_drvdata(pdev, st);
 172         ret = sysfs_create_group(&pdev->dev.kobj, &st->attr_group);
 173         if (ret < 0)
 174                 goto error_free_attrs;
 175
 176         st->hwmon_dev = hwmon_device_register(&pdev->dev);
 177         if (IS_ERR(st->hwmon_dev)) {
 178                 ret = PTR_ERR(st->hwmon_dev);
 179                 goto error_remove_group;
 180         }
 181         return 0;
 182
 183 error_remove_group:
 184         sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 185 error_free_attrs:
 186         iio_hwmon_free_attrs(st);
 187         kfree(st->attrs);
 188 error_release_channels:
 189         iio_channel_release_all(st->channels);
 190 error_free_state:
 191         kfree(st);
 192 error_ret:
 193         return ret;
 194 }
 195
 196 static int __devexit iio_hwmon_remove(struct platform_device *pdev)
 197 {
 198         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 199
 200         hwmon_device_unregister(st->hwmon_dev);
 201         sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 202         iio_hwmon_free_attrs(st);
 203         kfree(st->attrs);
 204         iio_channel_release_all(st->channels);
 205
 206         return 0;
 207 }
 208
 209 static struct platform_driver __refdata iio_hwmon_driver = {
 210         .driver = {
 211                 .name = "iio_hwmon",
 212                 .owner = THIS_MODULE,
 213         },
 214         .probe = iio_hwmon_probe,
 215         .remove = __devexit_p(iio_hwmon_remove),
 216 };
 217
 218 module_platform_driver(iio_hwmon_driver);
 219
 220 MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
 221 MODULE_DESCRIPTION("IIO to hwmon driver");
 222 MODULE_LICENSE("GPL v2");