drivers/hwmon/ad7314.c

   1 /*
   2  * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
   3  *
   4  * Copyright 2010 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  *
   8  * Conversion to hwmon from IIO done by Jonathan Cameron <jic23@cam.ac.uk>
   9  */
  10 #include <linux/device.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/module.h>
  16 #include <linux/err.h>
  17 #include <linux/hwmon.h>
  18 #include <linux/hwmon-sysfs.h>
  19
  20 /*
  21  * AD7314 power mode
  22  */
  23 #define AD7314_PD               0x2000
  24
  25 /*
  26  * AD7314 temperature masks
  27  */
  28 #define AD7314_TEMP_SIGN                0x200
  29 #define AD7314_TEMP_MASK                0x7FE0
  30 #define AD7314_TEMP_OFFSET              5
  31
  32 /*
  33  * ADT7301 and ADT7302 temperature masks
  34  */
  35 #define ADT7301_TEMP_SIGN               0x2000
  36 #define ADT7301_TEMP_MASK               0x3FFF
  37
  38 enum ad7314_variant {
  39         adt7301,
  40         adt7302,
  41         ad7314,
  42 };
  43
  44 struct ad7314_data {
  45         struct spi_device       *spi_dev;
  46         struct device           *hwmon_dev;
  47         u16 rx ____cacheline_aligned;
  48 };
  49
  50 static int ad7314_spi_read(struct ad7314_data *chip, s16 *data)
  51 {
  52         int ret;
  53
  54         ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
  55         if (ret < 0) {
  56                 dev_err(&chip->spi_dev->dev, "SPI read error\n");
  57                 return ret;
  58         }
  59
  60         *data = be16_to_cpu(chip->rx);
  61
  62         return ret;
  63 }
  64
  65 static ssize_t ad7314_show_temperature(struct device *dev,
  66                 struct device_attribute *attr,
  67                 char *buf)
  68 {
  69         struct ad7314_data *chip = dev_get_drvdata(dev);
  70         s16 data;
  71         int ret;
  72
  73         ret = ad7314_spi_read(chip, &data);
  74         if (ret < 0)
  75                 return ret;
  76         switch (spi_get_device_id(chip->spi_dev)->driver_data) {
  77         case ad7314:
  78                 data = (data & AD7314_TEMP_MASK) >> AD7314_TEMP_OFFSET;
  79                 data = (data << 6) >> 6;
  80
  81                 return sprintf(buf, "%d\n", 250 * data);
  82         case adt7301:
  83         case adt7302:
  84                 /*
  85                  * Documented as a 13 bit twos complement register
  86                  * with a sign bit - which is a 14 bit 2's complement
  87                  * register.  1lsb - 31.25 milli degrees centigrade
  88                  */
  89                 data &= ADT7301_TEMP_MASK;
  90                 data = (data << 2) >> 2;
  91
  92                 return sprintf(buf, "%d\n",
  93                                DIV_ROUND_CLOSEST(data * 3125, 100));
  94         default:
  95                 return -EINVAL;
  96         }
  97 }
  98
  99 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
 100                           ad7314_show_temperature, NULL, 0);
 101
 102 static struct attribute *ad7314_attributes[] = {
 103         &sensor_dev_attr_temp1_input.dev_attr.attr,
 104         NULL,
 105 };
 106
 107 static const struct attribute_group ad7314_group = {
 108         .attrs = ad7314_attributes,
 109 };
 110
 111 static int __devinit ad7314_probe(struct spi_device *spi_dev)
 112 {
 113         int ret;
 114         struct ad7314_data *chip;
 115
 116         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 117         if (chip == NULL) {
 118                 ret = -ENOMEM;
 119                 goto error_ret;
 120         }
 121         dev_set_drvdata(&spi_dev->dev, chip);
 122
 123         ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
 124         if (ret < 0)
 125                 goto error_free_chip;
 126         chip->hwmon_dev = hwmon_device_register(&spi_dev->dev);
 127         if (IS_ERR(chip->hwmon_dev)) {
 128                 ret = PTR_ERR(chip->hwmon_dev);
 129                 goto error_remove_group;
 130         }
 131
 132         return 0;
 133 error_remove_group:
 134         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 135 error_free_chip:
 136         kfree(chip);
 137 error_ret:
 138         return ret;
 139 }
 140
 141 static int __devexit ad7314_remove(struct spi_device *spi_dev)
 142 {
 143         struct ad7314_data *chip = dev_get_drvdata(&spi_dev->dev);
 144
 145         hwmon_device_unregister(chip->hwmon_dev);
 146         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 147         kfree(chip);
 148
 149         return 0;
 150 }
 151
 152 static const struct spi_device_id ad7314_id[] = {
 153         { "adt7301", adt7301 },
 154         { "adt7302", adt7302 },
 155         { "ad7314", ad7314 },
 156         { }
 157 };
 158 MODULE_DEVICE_TABLE(spi, ad7314_id);
 159
 160 static struct spi_driver ad7314_driver = {
 161         .driver = {
 162                 .name = "ad7314",
 163                 .owner = THIS_MODULE,
 164         },
 165         .probe = ad7314_probe,
 166         .remove = __devexit_p(ad7314_remove),
 167         .id_table = ad7314_id,
 168 };
 169
 170 static __init int ad7314_init(void)
 171 {
 172         return spi_register_driver(&ad7314_driver);
 173 }
 174 module_init(ad7314_init);
 175
 176 static __exit void ad7314_exit(void)
 177 {
 178         spi_unregister_driver(&ad7314_driver);
 179 }
 180 module_exit(ad7314_exit);
 181
 182 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 183 MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital"
 184                         " temperature sensor driver");
 185 MODULE_LICENSE("GPL v2");