text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
   *
   * Copyright 2010 Analog Devices Inc.
   *
   * Conversion to hwmon from IIO done by Jonathan Cameron <jic23@cam.ac.uk>
   */
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/sysfs.h>
  #include <linux/spi/spi.h>
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/bitops.h>
  
  /*
   * AD7314 temperature masks
   */
  #define AD7314_TEMP_MASK		0x7FE0
  #define AD7314_TEMP_SHIFT		5
  
  /*
   * ADT7301 and ADT7302 temperature masks
   */
  #define ADT7301_TEMP_MASK		0x3FFF
  
  enum ad7314_variant {
  	adt7301,
  	adt7302,
  	ad7314,
  };
  
  struct ad7314_data {
  	struct spi_device	*spi_dev;
  	u16 rx ____cacheline_aligned;
  };
  
  static int ad7314_spi_read(struct ad7314_data *chip)
  {
  	int ret;
  
  	ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
  	if (ret < 0) {
  		dev_err(&chip->spi_dev->dev, "SPI read error\n");
  		return ret;
  	}
  
  	return be16_to_cpu(chip->rx);
  }
  
  static ssize_t ad7314_temperature_show(struct device *dev,
  				       struct device_attribute *attr,
  				       char *buf)
  {
  	struct ad7314_data *chip = dev_get_drvdata(dev);
  	s16 data;
  	int ret;
  
  	ret = ad7314_spi_read(chip);
  	if (ret < 0)
  		return ret;
  	switch (spi_get_device_id(chip->spi_dev)->driver_data) {
  	case ad7314:
  		data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
  		data = sign_extend32(data, 9);
  
  		return sprintf(buf, "%d\n", 250 * data);
  	case adt7301:
  	case adt7302:
  		/*
  		 * Documented as a 13 bit twos complement register
  		 * with a sign bit - which is a 14 bit 2's complement
  		 * register.  1lsb - 31.25 milli degrees centigrade
  		 */
  		data = ret & ADT7301_TEMP_MASK;
  		data = sign_extend32(data, 13);
  
  		return sprintf(buf, "%d\n",
  			       DIV_ROUND_CLOSEST(data * 3125, 100));
  	default:
  		return -EINVAL;
  	}
  }
  
  static SENSOR_DEVICE_ATTR_RO(temp1_input, ad7314_temperature, 0);
  
  static struct attribute *ad7314_attrs[] = {
  	&sensor_dev_attr_temp1_input.dev_attr.attr,
  	NULL,
  };
  
  ATTRIBUTE_GROUPS(ad7314);
  
  static int ad7314_probe(struct spi_device *spi_dev)
  {
  	struct ad7314_data *chip;
  	struct device *hwmon_dev;
  
  	chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
  	if (chip == NULL)
  		return -ENOMEM;
  
  	chip->spi_dev = spi_dev;
  	hwmon_dev = devm_hwmon_device_register_with_groups(&spi_dev->dev,
  							   spi_dev->modalias,
  							   chip, ad7314_groups);
  	return PTR_ERR_OR_ZERO(hwmon_dev);
  }
  
  static const struct spi_device_id ad7314_id[] = {
  	{ "adt7301", adt7301 },
  	{ "adt7302", adt7302 },
  	{ "ad7314", ad7314 },
  	{ }
  };
  MODULE_DEVICE_TABLE(spi, ad7314_id);
  
  static struct spi_driver ad7314_driver = {
  	.driver = {
  		.name = "ad7314",
  	},
  	.probe = ad7314_probe,
  	.id_table = ad7314_id,
  };
  
  module_spi_driver(ad7314_driver);
  
  MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
  MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
  MODULE_LICENSE("GPL v2");
  