LXR linux/drivers/hwmon/max31722.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI
   4 * digital thermometer and thermostats.
   5 *
   6 * Copyright (c) 2016, Intel Corporation.
   7 */
   8
   9#include <linux/hwmon.h>
  10#include <linux/hwmon-sysfs.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/spi/spi.h>
  14
  15#define MAX31722_REG_CFG                                0x00
  16#define MAX31722_REG_TEMP_LSB                           0x01
  17
  18#define MAX31722_MODE_CONTINUOUS                        0x00
  19#define MAX31722_MODE_STANDBY                           0x01
  20#define MAX31722_MODE_MASK                              0xFE
  21#define MAX31722_RESOLUTION_12BIT                       0x06
  22#define MAX31722_WRITE_MASK                             0x80
  23
  24struct max31722_data {
  25        struct device *hwmon_dev;
  26        struct spi_device *spi_device;
  27        u8 mode;
  28};
  29
  30static int max31722_set_mode(struct max31722_data *data, u8 mode)
  31{
  32        int ret;
  33        struct spi_device *spi = data->spi_device;
  34        u8 buf[2] = {
  35                MAX31722_REG_CFG | MAX31722_WRITE_MASK,
  36                (data->mode & MAX31722_MODE_MASK) | mode
  37        };
  38
  39        ret = spi_write(spi, &buf, sizeof(buf));
  40        if (ret < 0) {
  41                dev_err(&spi->dev, "failed to set sensor mode.\n");
  42                return ret;
  43        }
  44        data->mode = (data->mode & MAX31722_MODE_MASK) | mode;
  45
  46        return 0;
  47}
  48
  49static ssize_t max31722_temp_show(struct device *dev,
  50                                  struct device_attribute *attr, char *buf)
  51{
  52        ssize_t ret;
  53        struct max31722_data *data = dev_get_drvdata(dev);
  54
  55        ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
  56        if (ret < 0)
  57                return ret;
  58        /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
  59        return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
  60}
  61
  62static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
  63
  64static struct attribute *max31722_attrs[] = {
  65        &sensor_dev_attr_temp1_input.dev_attr.attr,
  66        NULL,
  67};
  68
  69ATTRIBUTE_GROUPS(max31722);
  70
  71static int max31722_probe(struct spi_device *spi)
  72{
  73        int ret;
  74        struct max31722_data *data;
  75
  76        data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
  77        if (!data)
  78                return -ENOMEM;
  79
  80        spi_set_drvdata(spi, data);
  81        data->spi_device = spi;
  82        /*
  83         * Set SD bit to 0 so we can have continuous measurements.
  84         * Set resolution to 12 bits for maximum precision.
  85         */
  86        data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
  87        ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
  88        if (ret < 0)
  89                return ret;
  90
  91        data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
  92                                                            spi->modalias,
  93                                                            data,
  94                                                            max31722_groups);
  95        if (IS_ERR(data->hwmon_dev)) {
  96                max31722_set_mode(data, MAX31722_MODE_STANDBY);
  97                return PTR_ERR(data->hwmon_dev);
  98        }
  99
 100        return 0;
 101}
 102
 103static int max31722_remove(struct spi_device *spi)
 104{
 105        struct max31722_data *data = spi_get_drvdata(spi);
 106        int ret;
 107
 108        hwmon_device_unregister(data->hwmon_dev);
 109
 110        ret = max31722_set_mode(data, MAX31722_MODE_STANDBY);
 111        if (ret)
 112                /* There is nothing we can do about this ... */
 113                dev_warn(&spi->dev, "Failed to put device in stand-by mode\n");
 114
 115        return 0;
 116}
 117
 118static int __maybe_unused max31722_suspend(struct device *dev)
 119{
 120        struct spi_device *spi_device = to_spi_device(dev);
 121        struct max31722_data *data = spi_get_drvdata(spi_device);
 122
 123        return max31722_set_mode(data, MAX31722_MODE_STANDBY);
 124}
 125
 126static int __maybe_unused max31722_resume(struct device *dev)
 127{
 128        struct spi_device *spi_device = to_spi_device(dev);
 129        struct max31722_data *data = spi_get_drvdata(spi_device);
 130
 131        return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
 132}
 133
 134static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
 135
 136static const struct spi_device_id max31722_spi_id[] = {
 137        {"max31722", 0},
 138        {"max31723", 0},
 139        {}
 140};
 141MODULE_DEVICE_TABLE(spi, max31722_spi_id);
 142
 143static struct spi_driver max31722_driver = {
 144        .driver = {
 145                .name = "max31722",
 146                .pm = &max31722_pm_ops,
 147        },
 148        .probe =            max31722_probe,
 149        .remove =           max31722_remove,
 150        .id_table =         max31722_spi_id,
 151};
 152
 153module_spi_driver(max31722_driver);
 154
 155MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
 156MODULE_DESCRIPTION("max31722 sensor driver");
 157MODULE_LICENSE("GPL v2");
 158