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 temperature masks
  22  */
  23 #define AD7314_TEMP_MASK                0x7FE0
  24 #define AD7314_TEMP_SHIFT               5
  25
  26 /*
  27  * ADT7301 and ADT7302 temperature masks
  28  */
  29 #define ADT7301_TEMP_MASK               0x3FFF
  30
  31 enum ad7314_variant {
  32         adt7301,
  33         adt7302,
  34         ad7314,
  35 };
  36
  37 struct ad7314_data {
  38         struct spi_device       *spi_dev;
  39         struct device           *hwmon_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 = (data << 6) >> 6;
  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 = (data << 2) >> 2;
  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_attributes[] = {
  94         &sensor_dev_attr_temp1_input.dev_attr.attr,
  95         NULL,
  96 };
  97
  98 static const struct attribute_group ad7314_group = {
  99         .attrs = ad7314_attributes,
 100 };
 101
 102 static int __devinit ad7314_probe(struct spi_device *spi_dev)
 103 {
 104         int ret;
 105         struct ad7314_data *chip;
 106
 107         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 108         if (chip == NULL) {
 109                 ret = -ENOMEM;
 110                 goto error_ret;
 111         }
 112         dev_set_drvdata(&spi_dev->dev, chip);
 113
 114         ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
 115         if (ret < 0)
 116                 goto error_free_chip;
 117         chip->hwmon_dev = hwmon_device_register(&spi_dev->dev);
 118         if (IS_ERR(chip->hwmon_dev)) {
 119                 ret = PTR_ERR(chip->hwmon_dev);
 120                 goto error_remove_group;
 121         }
 122         chip->spi_dev = spi_dev;
 123
 124         return 0;
 125 error_remove_group:
 126         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 127 error_free_chip:
 128         kfree(chip);
 129 error_ret:
 130         return ret;
 131 }
 132
 133 static int __devexit ad7314_remove(struct spi_device *spi_dev)
 134 {
 135         struct ad7314_data *chip = dev_get_drvdata(&spi_dev->dev);
 136
 137         hwmon_device_unregister(chip->hwmon_dev);
 138         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 139         kfree(chip);
 140
 141         return 0;
 142 }
 143
 144 static const struct spi_device_id ad7314_id[] = {
 145         { "adt7301", adt7301 },
 146         { "adt7302", adt7302 },
 147         { "ad7314", ad7314 },
 148         { }
 149 };
 150 MODULE_DEVICE_TABLE(spi, ad7314_id);
 151
 152 static struct spi_driver ad7314_driver = {
 153         .driver = {
 154                 .name = "ad7314",
 155                 .owner = THIS_MODULE,
 156         },
 157         .probe = ad7314_probe,
 158         .remove = __devexit_p(ad7314_remove),
 159         .id_table = ad7314_id,
 160 };
 161
 162 module_spi_driver(ad7314_driver);
 163
 164 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 165 MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital"
 166                         " temperature sensor driver");
 167 MODULE_LICENSE("GPL v2");