drivers/hwmon/max197.c

   1 /*
   2  * Maxim MAX197 A/D Converter driver
   3  *
   4  * Copyright (c) 2012 Savoir-faire Linux Inc.
   5  *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * For further information, see the Documentation/hwmon/max197 file.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/err.h>
  18 #include <linux/slab.h>
  19 #include <linux/mutex.h>
  20 #include <linux/device.h>
  21 #include <linux/sysfs.h>
  22 #include <linux/hwmon.h>
  23 #include <linux/hwmon-sysfs.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/platform_data/max197.h>
  26
  27 #define MAX199_LIMIT    4000            /* 4V */
  28 #define MAX197_LIMIT    10000           /* 10V */
  29
  30 #define MAX197_NUM_CH   8               /* 8 Analog Input Channels */
  31
  32 /* Control byte format */
  33 #define MAX197_BIP      (1 << 3)        /* Bipolarity */
  34 #define MAX197_RNG      (1 << 4)        /* Full range */
  35
  36 #define MAX197_SCALE    12207           /* Scale coefficient for raw data */
  37
  38 /* List of supported chips */
  39 enum max197_chips { max197, max199 };
  40
  41 /**
  42  * struct max197_data - device instance specific data
  43  * @pdata:              Platform data.
  44  * @hwmon_dev:          The hwmon device.
  45  * @lock:               Read/Write mutex.
  46  * @limit:              Max range value (10V for MAX197, 4V for MAX199).
  47  * @scale:              Need to scale.
  48  * @ctrl_bytes:         Channels control byte.
  49  */
  50 struct max197_data {
  51         struct max197_platform_data *pdata;
  52         struct device *hwmon_dev;
  53         struct mutex lock;
  54         int limit;
  55         bool scale;
  56         u8 ctrl_bytes[MAX197_NUM_CH];
  57 };
  58
  59 static inline void max197_set_unipolarity(struct max197_data *data, int channel)
  60 {
  61         data->ctrl_bytes[channel] &= ~MAX197_BIP;
  62 }
  63
  64 static inline void max197_set_bipolarity(struct max197_data *data, int channel)
  65 {
  66         data->ctrl_bytes[channel] |= MAX197_BIP;
  67 }
  68
  69 static inline void max197_set_half_range(struct max197_data *data, int channel)
  70 {
  71         data->ctrl_bytes[channel] &= ~MAX197_RNG;
  72 }
  73
  74 static inline void max197_set_full_range(struct max197_data *data, int channel)
  75 {
  76         data->ctrl_bytes[channel] |= MAX197_RNG;
  77 }
  78
  79 static inline bool max197_is_bipolar(struct max197_data *data, int channel)
  80 {
  81         return data->ctrl_bytes[channel] & MAX197_BIP;
  82 }
  83
  84 static inline bool max197_is_full_range(struct max197_data *data, int channel)
  85 {
  86         return data->ctrl_bytes[channel] & MAX197_RNG;
  87 }
  88
  89 /* Function called on read access on in{0,1,2,3,4,5,6,7}_{min,max} */
  90 static ssize_t max197_show_range(struct device *dev,
  91                                  struct device_attribute *devattr, char *buf)
  92 {
  93         struct max197_data *data = dev_get_drvdata(dev);
  94         struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
  95         int channel = attr->index;
  96         bool is_min = attr->nr;
  97         int range;
  98
  99         if (mutex_lock_interruptible(&data->lock))
 100                 return -ERESTARTSYS;
 101
 102         range = max197_is_full_range(data, channel) ?
 103                 data->limit : data->limit / 2;
 104         if (is_min) {
 105                 if (max197_is_bipolar(data, channel))
 106                         range = -range;
 107                 else
 108                         range = 0;
 109         }
 110
 111         mutex_unlock(&data->lock);
 112
 113         return sprintf(buf, "%d\n", range);
 114 }
 115
 116 /* Function called on write access on in{0,1,2,3,4,5,6,7}_{min,max} */
 117 static ssize_t max197_store_range(struct device *dev,
 118                                   struct device_attribute *devattr,
 119                                   const char *buf, size_t count)
 120 {
 121         struct max197_data *data = dev_get_drvdata(dev);
 122         struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
 123         int channel = attr->index;
 124         bool is_min = attr->nr;
 125         long value;
 126         int half = data->limit / 2;
 127         int full = data->limit;
 128
 129         if (kstrtol(buf, 10, &value))
 130                 return -EINVAL;
 131
 132         if (is_min) {
 133                 if (value <= -full)
 134                         value = -full;
 135                 else if (value < 0)
 136                         value = -half;
 137                 else
 138                         value = 0;
 139         } else {
 140                 if (value >= full)
 141                         value = full;
 142                 else
 143                         value = half;
 144         }
 145
 146         if (mutex_lock_interruptible(&data->lock))
 147                 return -ERESTARTSYS;
 148
 149         if (value == 0) {
 150                 /* We can deduce only the polarity */
 151                 max197_set_unipolarity(data, channel);
 152         } else if (value == -half) {
 153                 max197_set_bipolarity(data, channel);
 154                 max197_set_half_range(data, channel);
 155         } else if (value == -full) {
 156                 max197_set_bipolarity(data, channel);
 157                 max197_set_full_range(data, channel);
 158         } else if (value == half) {
 159                 /* We can deduce only the range */
 160                 max197_set_half_range(data, channel);
 161         } else if (value == full) {
 162                 /* We can deduce only the range */
 163                 max197_set_full_range(data, channel);
 164         }
 165
 166         mutex_unlock(&data->lock);
 167
 168         return count;
 169 }
 170
 171 /* Function called on read access on in{0,1,2,3,4,5,6,7}_input */
 172 static ssize_t max197_show_input(struct device *dev,
 173                                  struct device_attribute *devattr,
 174                                  char *buf)
 175 {
 176         struct max197_data *data = dev_get_drvdata(dev);
 177         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 178         int channel = attr->index;
 179         s32 value;
 180         int ret;
 181
 182         if (mutex_lock_interruptible(&data->lock))
 183                 return -ERESTARTSYS;
 184
 185         ret = data->pdata->convert(data->ctrl_bytes[channel]);
 186         if (ret < 0) {
 187                 dev_err(dev, "conversion failed\n");
 188                 goto unlock;
 189         }
 190         value = ret;
 191
 192         /*
 193          * Coefficient to apply on raw value.
 194          * See Table 1. Full Scale and Zero Scale in the MAX197 datasheet.
 195          */
 196         if (data->scale) {
 197                 value *= MAX197_SCALE;
 198                 if (max197_is_full_range(data, channel))
 199                         value *= 2;
 200                 value /= 10000;
 201         }
 202
 203         ret = sprintf(buf, "%d\n", value);
 204
 205 unlock:
 206         mutex_unlock(&data->lock);
 207         return ret;
 208 }
 209
 210 static ssize_t max197_show_name(struct device *dev,
 211                                 struct device_attribute *attr, char *buf)
 212 {
 213         struct platform_device *pdev = to_platform_device(dev);
 214         return sprintf(buf, "%s\n", pdev->name);
 215 }
 216
 217 #define MAX197_SENSOR_DEVICE_ATTR_CH(chan)                              \
 218         static SENSOR_DEVICE_ATTR(in##chan##_input, S_IRUGO,            \
 219                                   max197_show_input, NULL, chan);       \
 220         static SENSOR_DEVICE_ATTR_2(in##chan##_min, S_IRUGO | S_IWUSR,  \
 221                                     max197_show_range,                  \
 222                                     max197_store_range,                 \
 223                                     true, chan);                        \
 224         static SENSOR_DEVICE_ATTR_2(in##chan##_max, S_IRUGO | S_IWUSR,  \
 225                                     max197_show_range,                  \
 226                                     max197_store_range,                 \
 227                                     false, chan)
 228
 229 #define MAX197_SENSOR_DEV_ATTR_IN(chan)                                 \
 230         &sensor_dev_attr_in##chan##_input.dev_attr.attr,                \
 231         &sensor_dev_attr_in##chan##_max.dev_attr.attr,                  \
 232         &sensor_dev_attr_in##chan##_min.dev_attr.attr
 233
 234 static DEVICE_ATTR(name, S_IRUGO, max197_show_name, NULL);
 235
 236 MAX197_SENSOR_DEVICE_ATTR_CH(0);
 237 MAX197_SENSOR_DEVICE_ATTR_CH(1);
 238 MAX197_SENSOR_DEVICE_ATTR_CH(2);
 239 MAX197_SENSOR_DEVICE_ATTR_CH(3);
 240 MAX197_SENSOR_DEVICE_ATTR_CH(4);
 241 MAX197_SENSOR_DEVICE_ATTR_CH(5);
 242 MAX197_SENSOR_DEVICE_ATTR_CH(6);
 243 MAX197_SENSOR_DEVICE_ATTR_CH(7);
 244
 245 static const struct attribute_group max197_sysfs_group = {
 246         .attrs = (struct attribute *[]) {
 247                 &dev_attr_name.attr,
 248                 MAX197_SENSOR_DEV_ATTR_IN(0),
 249                 MAX197_SENSOR_DEV_ATTR_IN(1),
 250                 MAX197_SENSOR_DEV_ATTR_IN(2),
 251                 MAX197_SENSOR_DEV_ATTR_IN(3),
 252                 MAX197_SENSOR_DEV_ATTR_IN(4),
 253                 MAX197_SENSOR_DEV_ATTR_IN(5),
 254                 MAX197_SENSOR_DEV_ATTR_IN(6),
 255                 MAX197_SENSOR_DEV_ATTR_IN(7),
 256                 NULL
 257         },
 258 };
 259
 260 static int max197_probe(struct platform_device *pdev)
 261 {
 262         int ch, ret;
 263         struct max197_data *data;
 264         struct max197_platform_data *pdata = dev_get_platdata(&pdev->dev);
 265         enum max197_chips chip = platform_get_device_id(pdev)->driver_data;
 266
 267         if (pdata == NULL) {
 268                 dev_err(&pdev->dev, "no platform data supplied\n");
 269                 return -EINVAL;
 270         }
 271
 272         if (pdata->convert == NULL) {
 273                 dev_err(&pdev->dev, "no convert function supplied\n");
 274                 return -EINVAL;
 275         }
 276
 277         data = devm_kzalloc(&pdev->dev, sizeof(struct max197_data), GFP_KERNEL);
 278         if (!data)
 279                 return -ENOMEM;
 280
 281         data->pdata = pdata;
 282         mutex_init(&data->lock);
 283
 284         if (chip == max197) {
 285                 data->limit = MAX197_LIMIT;
 286                 data->scale = true;
 287         } else {
 288                 data->limit = MAX199_LIMIT;
 289                 data->scale = false;
 290         }
 291
 292         for (ch = 0; ch < MAX197_NUM_CH; ch++)
 293                 data->ctrl_bytes[ch] = (u8) ch;
 294
 295         platform_set_drvdata(pdev, data);
 296
 297         ret = sysfs_create_group(&pdev->dev.kobj, &max197_sysfs_group);
 298         if (ret) {
 299                 dev_err(&pdev->dev, "sysfs create group failed\n");
 300                 return ret;
 301         }
 302
 303         data->hwmon_dev = hwmon_device_register(&pdev->dev);
 304         if (IS_ERR(data->hwmon_dev)) {
 305                 ret = PTR_ERR(data->hwmon_dev);
 306                 dev_err(&pdev->dev, "hwmon device register failed\n");
 307                 goto error;
 308         }
 309
 310         return 0;
 311
 312 error:
 313         sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
 314         return ret;
 315 }
 316
 317 static int max197_remove(struct platform_device *pdev)
 318 {
 319         struct max197_data *data = platform_get_drvdata(pdev);
 320
 321         hwmon_device_unregister(data->hwmon_dev);
 322         sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
 323
 324         return 0;
 325 }
 326
 327 static const struct platform_device_id max197_device_ids[] = {
 328         { "max197", max197 },
 329         { "max199", max199 },
 330         { }
 331 };
 332 MODULE_DEVICE_TABLE(platform, max197_device_ids);
 333
 334 static struct platform_driver max197_driver = {
 335         .driver = {
 336                 .name = "max197",
 337         },
 338         .probe = max197_probe,
 339         .remove = max197_remove,
 340         .id_table = max197_device_ids,
 341 };
 342 module_platform_driver(max197_driver);
 343
 344 MODULE_LICENSE("GPL");
 345 MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
 346 MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");