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
  24 struct max31722_data {
  25         struct device *hwmon_dev;
  26         struct spi_device *spi_device;
  27         u8 mode;
  28 };
  29
  30 static 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
  49 static 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
  62 static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
  63
  64 static struct attribute *max31722_attrs[] = {
  65         &sensor_dev_attr_temp1_input.dev_attr.attr,
  66         NULL,
  67 };
  68
  69 ATTRIBUTE_GROUPS(max31722);
  70
  71 static 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
 103 static void 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
 116 static int max31722_suspend(struct device *dev)
 117 {
 118         struct spi_device *spi_device = to_spi_device(dev);
 119         struct max31722_data *data = spi_get_drvdata(spi_device);
 120
 121         return max31722_set_mode(data, MAX31722_MODE_STANDBY);
 122 }
 123
 124 static int max31722_resume(struct device *dev)
 125 {
 126         struct spi_device *spi_device = to_spi_device(dev);
 127         struct max31722_data *data = spi_get_drvdata(spi_device);
 128
 129         return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
 130 }
 131
 132 static DEFINE_SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
 133
 134 static const struct spi_device_id max31722_spi_id[] = {
 135         {"max31722", 0},
 136         {"max31723", 0},
 137         {}
 138 };
 139 MODULE_DEVICE_TABLE(spi, max31722_spi_id);
 140
 141 static struct spi_driver max31722_driver = {
 142         .driver = {
 143                 .name = "max31722",
 144                 .pm = pm_sleep_ptr(&max31722_pm_ops),
 145         },
 146         .probe =            max31722_probe,
 147         .remove =           max31722_remove,
 148         .id_table =         max31722_spi_id,
 149 };
 150
 151 module_spi_driver(max31722_driver);
 152
 153 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
 154 MODULE_DESCRIPTION("max31722 sensor driver");
 155 MODULE_LICENSE("GPL v2");