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/acpi.h>
  10 #include <linux/hwmon.h>
  11 #include <linux/hwmon-sysfs.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/spi/spi.h>
  15
  16 #define MAX31722_REG_CFG                                0x00
  17 #define MAX31722_REG_TEMP_LSB                           0x01
  18
  19 #define MAX31722_MODE_CONTINUOUS                        0x00
  20 #define MAX31722_MODE_STANDBY                           0x01
  21 #define MAX31722_MODE_MASK                              0xFE
  22 #define MAX31722_RESOLUTION_12BIT                       0x06
  23 #define MAX31722_WRITE_MASK                             0x80
  24
  25 struct max31722_data {
  26         struct device *hwmon_dev;
  27         struct spi_device *spi_device;
  28         u8 mode;
  29 };
  30
  31 static int max31722_set_mode(struct max31722_data *data, u8 mode)
  32 {
  33         int ret;
  34         struct spi_device *spi = data->spi_device;
  35         u8 buf[2] = {
  36                 MAX31722_REG_CFG | MAX31722_WRITE_MASK,
  37                 (data->mode & MAX31722_MODE_MASK) | mode
  38         };
  39
  40         ret = spi_write(spi, &buf, sizeof(buf));
  41         if (ret < 0) {
  42                 dev_err(&spi->dev, "failed to set sensor mode.\n");
  43                 return ret;
  44         }
  45         data->mode = (data->mode & MAX31722_MODE_MASK) | mode;
  46
  47         return 0;
  48 }
  49
  50 static ssize_t max31722_temp_show(struct device *dev,
  51                                   struct device_attribute *attr, char *buf)
  52 {
  53         ssize_t ret;
  54         struct max31722_data *data = dev_get_drvdata(dev);
  55
  56         ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
  57         if (ret < 0)
  58                 return ret;
  59         /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
  60         return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
  61 }
  62
  63 static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
  64
  65 static struct attribute *max31722_attrs[] = {
  66         &sensor_dev_attr_temp1_input.dev_attr.attr,
  67         NULL,
  68 };
  69
  70 ATTRIBUTE_GROUPS(max31722);
  71
  72 static int max31722_probe(struct spi_device *spi)
  73 {
  74         int ret;
  75         struct max31722_data *data;
  76
  77         data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
  78         if (!data)
  79                 return -ENOMEM;
  80
  81         spi_set_drvdata(spi, data);
  82         data->spi_device = spi;
  83         /*
  84          * Set SD bit to 0 so we can have continuous measurements.
  85          * Set resolution to 12 bits for maximum precision.
  86          */
  87         data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
  88         ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
  89         if (ret < 0)
  90                 return ret;
  91
  92         data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
  93                                                             spi->modalias,
  94                                                             data,
  95                                                             max31722_groups);
  96         if (IS_ERR(data->hwmon_dev)) {
  97                 max31722_set_mode(data, MAX31722_MODE_STANDBY);
  98                 return PTR_ERR(data->hwmon_dev);
  99         }
 100
 101         return 0;
 102 }
 103
 104 static int max31722_remove(struct spi_device *spi)
 105 {
 106         struct max31722_data *data = spi_get_drvdata(spi);
 107
 108         hwmon_device_unregister(data->hwmon_dev);
 109
 110         return max31722_set_mode(data, MAX31722_MODE_STANDBY);
 111 }
 112
 113 static int __maybe_unused max31722_suspend(struct device *dev)
 114 {
 115         struct spi_device *spi_device = to_spi_device(dev);
 116         struct max31722_data *data = spi_get_drvdata(spi_device);
 117
 118         return max31722_set_mode(data, MAX31722_MODE_STANDBY);
 119 }
 120
 121 static int __maybe_unused max31722_resume(struct device *dev)
 122 {
 123         struct spi_device *spi_device = to_spi_device(dev);
 124         struct max31722_data *data = spi_get_drvdata(spi_device);
 125
 126         return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
 127 }
 128
 129 static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
 130
 131 static const struct spi_device_id max31722_spi_id[] = {
 132         {"max31722", 0},
 133         {"max31723", 0},
 134         {}
 135 };
 136
 137 static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = {
 138         {"MAX31722", 0},
 139         {"MAX31723", 0},
 140         {}
 141 };
 142
 143 MODULE_DEVICE_TABLE(spi, max31722_spi_id);
 144
 145 static struct spi_driver max31722_driver = {
 146         .driver = {
 147                 .name = "max31722",
 148                 .pm = &max31722_pm_ops,
 149                 .acpi_match_table = ACPI_PTR(max31722_acpi_id),
 150         },
 151         .probe =            max31722_probe,
 152         .remove =           max31722_remove,
 153         .id_table =         max31722_spi_id,
 154 };
 155
 156 module_spi_driver(max31722_driver);
 157
 158 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
 159 MODULE_DESCRIPTION("max31722 sensor driver");
 160 MODULE_LICENSE("GPL v2");