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         struct device           *hwmon_dev;
  41         u16 rx ____cacheline_aligned;
  42 };
  43
  44 static int ad7314_spi_read(struct ad7314_data *chip)
  45 {
  46         int ret;
  47
  48         ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
  49         if (ret < 0) {
  50                 dev_err(&chip->spi_dev->dev, "SPI read error\n");
  51                 return ret;
  52         }
  53
  54         return be16_to_cpu(chip->rx);
  55 }
  56
  57 static ssize_t ad7314_show_temperature(struct device *dev,
  58                 struct device_attribute *attr,
  59                 char *buf)
  60 {
  61         struct ad7314_data *chip = dev_get_drvdata(dev);
  62         s16 data;
  63         int ret;
  64
  65         ret = ad7314_spi_read(chip);
  66         if (ret < 0)
  67                 return ret;
  68         switch (spi_get_device_id(chip->spi_dev)->driver_data) {
  69         case ad7314:
  70                 data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
  71                 data = sign_extend32(data, 9);
  72
  73                 return sprintf(buf, "%d\n", 250 * data);
  74         case adt7301:
  75         case adt7302:
  76                 /*
  77                  * Documented as a 13 bit twos complement register
  78                  * with a sign bit - which is a 14 bit 2's complement
  79                  * register.  1lsb - 31.25 milli degrees centigrade
  80                  */
  81                 data = ret & ADT7301_TEMP_MASK;
  82                 data = sign_extend32(data, 13);
  83
  84                 return sprintf(buf, "%d\n",
  85                                DIV_ROUND_CLOSEST(data * 3125, 100));
  86         default:
  87                 return -EINVAL;
  88         }
  89 }
  90
  91 static ssize_t ad7314_show_name(struct device *dev,
  92                                 struct device_attribute *devattr, char *buf)
  93 {
  94         return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
  95 }
  96
  97 static DEVICE_ATTR(name, S_IRUGO, ad7314_show_name, NULL);
  98 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
  99                           ad7314_show_temperature, NULL, 0);
 100
 101 static struct attribute *ad7314_attributes[] = {
 102         &dev_attr_name.attr,
 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 ad7314_probe(struct spi_device *spi_dev)
 112 {
 113         int ret;
 114         struct ad7314_data *chip;
 115
 116         chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
 117         if (chip == NULL)
 118                 return -ENOMEM;
 119
 120         spi_set_drvdata(spi_dev, chip);
 121
 122         ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
 123         if (ret < 0)
 124                 return ret;
 125
 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         chip->spi_dev = spi_dev;
 132
 133         return 0;
 134 error_remove_group:
 135         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 136         return ret;
 137 }
 138
 139 static int ad7314_remove(struct spi_device *spi_dev)
 140 {
 141         struct ad7314_data *chip = spi_get_drvdata(spi_dev);
 142
 143         hwmon_device_unregister(chip->hwmon_dev);
 144         sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
 145
 146         return 0;
 147 }
 148
 149 static const struct spi_device_id ad7314_id[] = {
 150         { "adt7301", adt7301 },
 151         { "adt7302", adt7302 },
 152         { "ad7314", ad7314 },
 153         { }
 154 };
 155 MODULE_DEVICE_TABLE(spi, ad7314_id);
 156
 157 static struct spi_driver ad7314_driver = {
 158         .driver = {
 159                 .name = "ad7314",
 160         },
 161         .probe = ad7314_probe,
 162         .remove = ad7314_remove,
 163         .id_table = ad7314_id,
 164 };
 165
 166 module_spi_driver(ad7314_driver);
 167
 168 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 169 MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
 170 MODULE_LICENSE("GPL v2");