// 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
#define AD7314_LEADING_ZEROS_MASK       BIT(15)

/*
 * ADT7301 and ADT7302 temperature masks
 */
#define ADT7301_TEMP_MASK               0x3FFF
#define ADT7301_LEADING_ZEROS_MASK      (BIT(15) | BIT(14))

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:
                if (ret & AD7314_LEADING_ZEROS_MASK) {
                        /* Invalid read-out, leading zero part is missing */
                        return -EIO;
                }
                data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
                data = sign_extend32(data, 9);

                return sprintf(buf, "%d\n", 250 * data);
        case adt7301:
        case adt7302:
                if (ret & ADT7301_LEADING_ZEROS_MASK) {
                        /* Invalid read-out, leading zero part is missing */
                        return -EIO;
                }
                /*
                 * 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");