drivers/hwmon/surface_fan.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Surface Fan driver for Surface System Aggregator Module. It provides access
   4  * to the fan's rpm through the hwmon system.
   5  *
   6  * Copyright (C) 2023 Ivor Wanders <[email protected]>
   7  */
   8
   9 #include <linux/hwmon.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/surface_aggregator/device.h>
  13 #include <linux/types.h>
  14
  15 // SSAM
  16 SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_fan_rpm_get, __le16, {
  17         .target_category = SSAM_SSH_TC_FAN,
  18         .command_id      = 0x01,
  19 });
  20
  21 static int surface_fan_hwmon_read(struct device *dev,
  22                                   enum hwmon_sensor_types type, u32 attr,
  23                                   int channel, long *val)
  24 {
  25         struct ssam_device *sdev = dev_get_drvdata(dev);
  26         int ret;
  27         __le16 value;
  28
  29         ret = __ssam_fan_rpm_get(sdev, &value);
  30         if (ret)
  31                 return ret;
  32
  33         *val = le16_to_cpu(value);
  34
  35         return 0;
  36 }
  37
  38 static const struct hwmon_channel_info *const surface_fan_info[] = {
  39         HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
  40         NULL
  41 };
  42
  43 static const struct hwmon_ops surface_fan_hwmon_ops = {
  44         .visible = 0444,
  45         .read = surface_fan_hwmon_read,
  46 };
  47
  48 static const struct hwmon_chip_info surface_fan_chip_info = {
  49         .ops = &surface_fan_hwmon_ops,
  50         .info = surface_fan_info,
  51 };
  52
  53 static int surface_fan_probe(struct ssam_device *sdev)
  54 {
  55         struct device *hdev;
  56
  57         hdev = devm_hwmon_device_register_with_info(&sdev->dev,
  58                                                     "surface_fan", sdev,
  59                                                     &surface_fan_chip_info,
  60                                                     NULL);
  61
  62         return PTR_ERR_OR_ZERO(hdev);
  63 }
  64
  65 static const struct ssam_device_id ssam_fan_match[] = {
  66         { SSAM_SDEV(FAN, SAM, 0x01, 0x01) },
  67         {},
  68 };
  69 MODULE_DEVICE_TABLE(ssam, ssam_fan_match);
  70
  71 static struct ssam_device_driver surface_fan = {
  72         .probe = surface_fan_probe,
  73         .match_table = ssam_fan_match,
  74         .driver = {
  75                 .name = "surface_fan",
  76                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
  77         },
  78 };
  79 module_ssam_device_driver(surface_fan);
  80
  81 MODULE_AUTHOR("Ivor Wanders <[email protected]>");
  82 MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
  83 MODULE_LICENSE("GPL");