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