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 #include <linux/bitops.h>
  20
  21 /*
  22  * AD7314 temperature masks
  23  */
  24 #define AD7314_TEMP_MASK                0x7FE0
  25 #define AD7314_TEMP_SHIFT               5
  26
  27 /*
  28  * ADT7301 and ADT7302 temperature masks
  29  */
  30 #define ADT7301_TEMP_MASK               0x3FFF
  31
  32 enum ad7314_variant {
  33         adt7301,
  34         adt7302,
  35         ad7314,
  36 };
  37
  38 struct ad7314_data {
  39         struct spi_device       *spi_dev;
  40         u16 rx ____cacheline_aligned;
  41 };
  42
  43 static int ad7314_spi_read(struct ad7314_data *chip)
  44 {
  45         int ret;
  46
  47         ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
  48         if (ret < 0) {
  49                 dev_err(&chip->spi_dev->dev, "SPI read error\n");
  50                 return ret;
  51         }
  52
  53         return be16_to_cpu(chip->rx);
  54 }
  55
  56 static ssize_t ad7314_show_temperature(struct device *dev,
  57                 struct device_attribute *attr,
  58                 char *buf)
  59 {
  60         struct ad7314_data *chip = dev_get_drvdata(dev);
  61         s16 data;
  62         int ret;
  63
  64         ret = ad7314_spi_read(chip);
  65         if (ret < 0)
  66                 return ret;
  67         switch (spi_get_device_id(chip->spi_dev)->driver_data) {
  68         case ad7314:
  69                 data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
  70                 data = sign_extend32(data, 9);
  71
  72                 return sprintf(buf, "%d\n", 250 * data);
  73         case adt7301:
  74         case adt7302:
  75                 /*
  76                  * Documented as a 13 bit twos complement register
  77                  * with a sign bit - which is a 14 bit 2's complement
  78                  * register.  1lsb - 31.25 milli degrees centigrade
  79                  */
  80                 data = ret & ADT7301_TEMP_MASK;
  81                 data = sign_extend32(data, 13);
  82
  83                 return sprintf(buf, "%d\n",
  84                                DIV_ROUND_CLOSEST(data * 3125, 100));
  85         default:
  86                 return -EINVAL;
  87         }
  88 }
  89
  90 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
  91                           ad7314_show_temperature, NULL, 0);
  92
  93 static struct attribute *ad7314_attrs[] = {
  94         &sensor_dev_attr_temp1_input.dev_attr.attr,
  95         NULL,
  96 };
  97
  98 ATTRIBUTE_GROUPS(ad7314);
  99
 100 static int ad7314_probe(struct spi_device *spi_dev)
 101 {
 102         struct ad7314_data *chip;
 103         struct device *hwmon_dev;
 104
 105         chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
 106         if (chip == NULL)
 107                 return -ENOMEM;
 108
 109         chip->spi_dev = spi_dev;
 110         hwmon_dev = devm_hwmon_device_register_with_groups(&spi_dev->dev,
 111                                                            spi_dev->modalias,
 112                                                            chip, ad7314_groups);
 113         return PTR_ERR_OR_ZERO(hwmon_dev);
 114 }
 115
 116 static const struct spi_device_id ad7314_id[] = {
 117         { "adt7301", adt7301 },
 118         { "adt7302", adt7302 },
 119         { "ad7314", ad7314 },
 120         { }
 121 };
 122 MODULE_DEVICE_TABLE(spi, ad7314_id);
 123
 124 static struct spi_driver ad7314_driver = {
 125         .driver = {
 126                 .name = "ad7314",
 127         },
 128         .probe = ad7314_probe,
 129         .id_table = ad7314_id,
 130 };
 131
 132 module_spi_driver(ad7314_driver);
 133
 134 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 135 MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
 136 MODULE_LICENSE("GPL v2");