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)
  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         return be16_to_cpu(chip->rx);
  61 }
  62
  63 static ssize_t ad7314_show_temperature(struct device *dev,
  64                 struct device_attribute *attr,
  65                 char *buf)
  66 {
  67         struct ad7314_data *chip = dev_get_drvdata(dev);
  68         s16 data;
  69         int ret;
  70
  71         ret = ad7314_spi_read(chip);
  72         if (ret < 0)
  73                 return ret;
  74         switch (spi_get_device_id(chip->spi_dev)->driver_data) {
  75         case ad7314:
  76                 data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_OFFSET;
  77                 data = (data << 6) >> 6;
  78
  79                 return sprintf(buf, "%d\n", 250 * data);
  80         case adt7301:
  81         case adt7302:
  82                 /*
  83                  * Documented as a 13 bit twos complement register
  84                  * with a sign bit - which is a 14 bit 2's complement
  85                  * register.  1lsb - 31.25 milli degrees centigrade
  86                  */
  87                 data = ret & ADT7301_TEMP_MASK;
  88                 data = (data << 2) >> 2;
  89
  90                 return sprintf(buf, "%d\n",
  91                                DIV_ROUND_CLOSEST(data * 3125, 100));
  92         default:
  93                 return -EINVAL;
  94         }
  95 }
  96
  97 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
  98                           ad7314_show_temperature, NULL, 0);
  99
 100 static struct attribute *ad7314_attributes[] = {
 101         &sensor_dev_attr_temp1_input.dev_attr.attr,
 102         NULL,
 103 };
 104
 105 static const struct attribute_group ad7314_group = {
 106         .attrs = ad7314_attributes,
 107 };
 108
 109 static int __devinit ad7314_probe(struct spi_device *spi_dev)
 110 {
 111         int ret;
 112         struct ad7314_data *chip;
 113
 114         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 115         if (chip == NULL) {
 116                 ret = -ENOMEM;
 117                 goto error_ret;
 118         }
 119         dev_set_drvdata(&spi_dev->dev, chip);
 120
 121         ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
 122         if (ret < 0)
 123                 goto error_free_chip;
 124         chip->hwmon_dev = hwmon_device_register(&spi_dev->dev);
 125         if (IS_ERR(chip->hwmon_dev)) {
 126                 ret = PTR_ERR(chip->hwmon_dev);
 127                 goto error_remove_group;
 128         }
 129         chip->spi_dev = spi_dev;
 130
 131         return 0;
 132 error_remove_group:
 133         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 134 error_free_chip:
 135         kfree(chip);
 136 error_ret:
 137         return ret;
 138 }
 139
 140 static int __devexit ad7314_remove(struct spi_device *spi_dev)
 141 {
 142         struct ad7314_data *chip = dev_get_drvdata(&spi_dev->dev);
 143
 144         hwmon_device_unregister(chip->hwmon_dev);
 145         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 146         kfree(chip);
 147
 148         return 0;
 149 }
 150
 151 static const struct spi_device_id ad7314_id[] = {
 152         { "adt7301", adt7301 },
 153         { "adt7302", adt7302 },
 154         { "ad7314", ad7314 },
 155         { }
 156 };
 157 MODULE_DEVICE_TABLE(spi, ad7314_id);
 158
 159 static struct spi_driver ad7314_driver = {
 160         .driver = {
 161                 .name = "ad7314",
 162                 .owner = THIS_MODULE,
 163         },
 164         .probe = ad7314_probe,
 165         .remove = __devexit_p(ad7314_remove),
 166         .id_table = ad7314_id,
 167 };
 168
 169 module_spi_driver(ad7314_driver);
 170
 171 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 172 MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital"
 173                         " temperature sensor driver");
 174 MODULE_LICENSE("GPL v2");