drivers/hwmon/sl28cpld-hwmon.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * sl28cpld hardware monitoring driver
   4  *
   5  * Copyright 2020 Kontron Europe GmbH
   6  */
   7
   8 #include <linux/bitfield.h>
   9 #include <linux/hwmon.h>
  10 #include <linux/kernel.h>
  11 #include <linux/mod_devicetable.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/property.h>
  15 #include <linux/regmap.h>
  16
  17 #define FAN_INPUT               0x00
  18 #define   FAN_SCALE_X8          BIT(7)
  19 #define   FAN_VALUE_MASK        GENMASK(6, 0)
  20
  21 struct sl28cpld_hwmon {
  22         struct regmap *regmap;
  23         u32 offset;
  24 };
  25
  26 static umode_t sl28cpld_hwmon_is_visible(const void *data,
  27                                          enum hwmon_sensor_types type,
  28                                          u32 attr, int channel)
  29 {
  30         return 0444;
  31 }
  32
  33 static int sl28cpld_hwmon_read(struct device *dev,
  34                                enum hwmon_sensor_types type, u32 attr,
  35                                int channel, long *input)
  36 {
  37         struct sl28cpld_hwmon *hwmon = dev_get_drvdata(dev);
  38         unsigned int value;
  39         int ret;
  40
  41         switch (attr) {
  42         case hwmon_fan_input:
  43                 ret = regmap_read(hwmon->regmap, hwmon->offset + FAN_INPUT,
  44                                   &value);
  45                 if (ret)
  46                         return ret;
  47                 /*
  48                  * The register has a 7 bit value and 1 bit which indicates the
  49                  * scale. If the MSB is set, then the lower 7 bit has to be
  50                  * multiplied by 8, to get the correct reading.
  51                  */
  52                 if (value & FAN_SCALE_X8)
  53                         value = FIELD_GET(FAN_VALUE_MASK, value) << 3;
  54
  55                 /*
  56                  * The counter period is 1000ms and the sysfs specification
  57                  * says we should asssume 2 pulses per revolution.
  58                  */
  59                 value *= 60 / 2;
  60
  61                 break;
  62         default:
  63                 return -EOPNOTSUPP;
  64         }
  65
  66         *input = value;
  67         return 0;
  68 }
  69
  70 static const u32 sl28cpld_hwmon_fan_config[] = {
  71         HWMON_F_INPUT,
  72         0
  73 };
  74
  75 static const struct hwmon_channel_info sl28cpld_hwmon_fan = {
  76         .type = hwmon_fan,
  77         .config = sl28cpld_hwmon_fan_config,
  78 };
  79
  80 static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
  81         &sl28cpld_hwmon_fan,
  82         NULL
  83 };
  84
  85 static const struct hwmon_ops sl28cpld_hwmon_ops = {
  86         .is_visible = sl28cpld_hwmon_is_visible,
  87         .read = sl28cpld_hwmon_read,
  88 };
  89
  90 static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
  91         .ops = &sl28cpld_hwmon_ops,
  92         .info = sl28cpld_hwmon_info,
  93 };
  94
  95 static int sl28cpld_hwmon_probe(struct platform_device *pdev)
  96 {
  97         struct sl28cpld_hwmon *hwmon;
  98         struct device *hwmon_dev;
  99         int ret;
 100
 101         if (!pdev->dev.parent)
 102                 return -ENODEV;
 103
 104         hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
 105         if (!hwmon)
 106                 return -ENOMEM;
 107
 108         hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
 109         if (!hwmon->regmap)
 110                 return -ENODEV;
 111
 112         ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset);
 113         if (ret)
 114                 return -EINVAL;
 115
 116         hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
 117                                 "sl28cpld_hwmon", hwmon,
 118                                 &sl28cpld_hwmon_chip_info, NULL);
 119         if (IS_ERR(hwmon_dev))
 120                 dev_err(&pdev->dev, "failed to register as hwmon device");
 121
 122         return PTR_ERR_OR_ZERO(hwmon_dev);
 123 }
 124
 125 static const struct of_device_id sl28cpld_hwmon_of_match[] = {
 126         { .compatible = "kontron,sl28cpld-fan" },
 127         {}
 128 };
 129 MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
 130
 131 static struct platform_driver sl28cpld_hwmon_driver = {
 132         .probe = sl28cpld_hwmon_probe,
 133         .driver = {
 134                 .name = "sl28cpld-fan",
 135                 .of_match_table = sl28cpld_hwmon_of_match,
 136         },
 137 };
 138 module_platform_driver(sl28cpld_hwmon_driver);
 139
 140 MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
 141 MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
 142 MODULE_LICENSE("GPL");