drivers/hwmon/max31722.c

   1 /*
   2  * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI
   3  * digital thermometer and thermostats.
   4  *
   5  * Copyright (c) 2016, Intel Corporation.
   6  *
   7  * This file is subject to the terms and conditions of version 2 of
   8  * the GNU General Public License. See the file COPYING in the main
   9  * directory of this archive for more details.
  10  */
  11
  12 #include <linux/acpi.h>
  13 #include <linux/hwmon.h>
  14 #include <linux/hwmon-sysfs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/spi/spi.h>
  18
  19 #define MAX31722_REG_CFG                                0x00
  20 #define MAX31722_REG_TEMP_LSB                           0x01
  21
  22 #define MAX31722_MODE_CONTINUOUS                        0x00
  23 #define MAX31722_MODE_STANDBY                           0x01
  24 #define MAX31722_MODE_MASK                              0xFE
  25 #define MAX31722_RESOLUTION_12BIT                       0x06
  26 #define MAX31722_WRITE_MASK                             0x80
  27
  28 struct max31722_data {
  29         struct device *hwmon_dev;
  30         struct spi_device *spi_device;
  31         u8 mode;
  32 };
  33
  34 static int max31722_set_mode(struct max31722_data *data, u8 mode)
  35 {
  36         int ret;
  37         struct spi_device *spi = data->spi_device;
  38         u8 buf[2] = {
  39                 MAX31722_REG_CFG | MAX31722_WRITE_MASK,
  40                 (data->mode & MAX31722_MODE_MASK) | mode
  41         };
  42
  43         ret = spi_write(spi, &buf, sizeof(buf));
  44         if (ret < 0) {
  45                 dev_err(&spi->dev, "failed to set sensor mode.\n");
  46                 return ret;
  47         }
  48         data->mode = (data->mode & MAX31722_MODE_MASK) | mode;
  49
  50         return 0;
  51 }
  52
  53 static ssize_t max31722_show_temp(struct device *dev,
  54                                   struct device_attribute *attr,
  55                                   char *buf)
  56 {
  57         ssize_t ret;
  58         struct max31722_data *data = dev_get_drvdata(dev);
  59
  60         ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
  61         if (ret < 0)
  62                 return ret;
  63         /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
  64         return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
  65 }
  66
  67 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
  68                           max31722_show_temp, NULL, 0);
  69
  70 static struct attribute *max31722_attrs[] = {
  71         &sensor_dev_attr_temp1_input.dev_attr.attr,
  72         NULL,
  73 };
  74
  75 ATTRIBUTE_GROUPS(max31722);
  76
  77 static int max31722_probe(struct spi_device *spi)
  78 {
  79         int ret;
  80         struct max31722_data *data;
  81
  82         data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
  83         if (!data)
  84                 return -ENOMEM;
  85
  86         spi_set_drvdata(spi, data);
  87         data->spi_device = spi;
  88         /*
  89          * Set SD bit to 0 so we can have continuous measurements.
  90          * Set resolution to 12 bits for maximum precision.
  91          */
  92         data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
  93         ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
  94         if (ret < 0)
  95                 return ret;
  96
  97         data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
  98                                                             spi->modalias,
  99                                                             data,
 100                                                             max31722_groups);
 101         if (IS_ERR(data->hwmon_dev)) {
 102                 max31722_set_mode(data, MAX31722_MODE_STANDBY);
 103                 return PTR_ERR(data->hwmon_dev);
 104         }
 105
 106         return 0;
 107 }
 108
 109 static int max31722_remove(struct spi_device *spi)
 110 {
 111         struct max31722_data *data = spi_get_drvdata(spi);
 112
 113         hwmon_device_unregister(data->hwmon_dev);
 114
 115         return max31722_set_mode(data, MAX31722_MODE_STANDBY);
 116 }
 117
 118 static 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
 126 static 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
 134 static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
 135
 136 static const struct spi_device_id max31722_spi_id[] = {
 137         {"max31722", 0},
 138         {"max31723", 0},
 139         {}
 140 };
 141
 142 static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = {
 143         {"MAX31722", 0},
 144         {"MAX31723", 0},
 145         {}
 146 };
 147
 148 MODULE_DEVICE_TABLE(spi, max31722_spi_id);
 149
 150 static struct spi_driver max31722_driver = {
 151         .driver = {
 152                 .name = "max31722",
 153                 .pm = &max31722_pm_ops,
 154                 .acpi_match_table = ACPI_PTR(max31722_acpi_id),
 155         },
 156         .probe =            max31722_probe,
 157         .remove =           max31722_remove,
 158         .id_table =         max31722_spi_id,
 159 };
 160
 161 module_spi_driver(max31722_driver);
 162
 163 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
 164 MODULE_DESCRIPTION("max31722 sensor driver");
 165 MODULE_LICENSE("GPL v2");