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
 32enum ad7314_variant {
 33	adt7301,
 34	adt7302,
 35	ad7314,
 36};
 37
 38struct ad7314_data {
 39	struct spi_device	*spi_dev;
 40	u16 rx ____cacheline_aligned;
 41};
 42
 43static 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
 56static 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
 90static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
 91			  ad7314_show_temperature, NULL, 0);
 92
 93static struct attribute *ad7314_attrs[] = {
 94	&sensor_dev_attr_temp1_input.dev_attr.attr,
 95	NULL,
 96};
 97
 98ATTRIBUTE_GROUPS(ad7314);
 99
100static 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
116static const struct spi_device_id ad7314_id[] = {
117	{ "adt7301", adt7301 },
118	{ "adt7302", adt7302 },
119	{ "ad7314", ad7314 },
120	{ }
121};
122MODULE_DEVICE_TABLE(spi, ad7314_id);
123
124static struct spi_driver ad7314_driver = {
125	.driver = {
126		.name = "ad7314",
127	},
128	.probe = ad7314_probe,
129	.id_table = ad7314_id,
130};
131
132module_spi_driver(ad7314_driver);
133
134MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
135MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
136MODULE_LICENSE("GPL v2");