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 // hwmon
  22 static umode_t surface_fan_hwmon_is_visible(const void *drvdata,
  23                                             enum hwmon_sensor_types type, u32 attr,
  24                                             int channel)
  25 {
  26         return 0444;
  27 }
  28
  29 static int surface_fan_hwmon_read(struct device *dev,
  30                                   enum hwmon_sensor_types type, u32 attr,
  31                                   int channel, long *val)
  32 {
  33         struct ssam_device *sdev = dev_get_drvdata(dev);
  34         int ret;
  35         __le16 value;
  36
  37         ret = __ssam_fan_rpm_get(sdev, &value);
  38         if (ret)
  39                 return ret;
  40
  41         *val = le16_to_cpu(value);
  42
  43         return 0;
  44 }
  45
  46 static const struct hwmon_channel_info *const surface_fan_info[] = {
  47         HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
  48         NULL
  49 };
  50
  51 static const struct hwmon_ops surface_fan_hwmon_ops = {
  52         .is_visible = surface_fan_hwmon_is_visible,
  53         .read = surface_fan_hwmon_read,
  54 };
  55
  56 static const struct hwmon_chip_info surface_fan_chip_info = {
  57         .ops = &surface_fan_hwmon_ops,
  58         .info = surface_fan_info,
  59 };
  60
  61 static int surface_fan_probe(struct ssam_device *sdev)
  62 {
  63         struct device *hdev;
  64
  65         hdev = devm_hwmon_device_register_with_info(&sdev->dev,
  66                                                     "surface_fan", sdev,
  67                                                     &surface_fan_chip_info,
  68                                                     NULL);
  69
  70         return PTR_ERR_OR_ZERO(hdev);
  71 }
  72
  73 static const struct ssam_device_id ssam_fan_match[] = {
  74         { SSAM_SDEV(FAN, SAM, 0x01, 0x01) },
  75         {},
  76 };
  77 MODULE_DEVICE_TABLE(ssam, ssam_fan_match);
  78
  79 static struct ssam_device_driver surface_fan = {
  80         .probe = surface_fan_probe,
  81         .match_table = ssam_fan_match,
  82         .driver = {
  83                 .name = "surface_fan",
  84                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
  85         },
  86 };
  87 module_ssam_device_driver(surface_fan);
  88
  89 MODULE_AUTHOR("Ivor Wanders <[email protected]>");
  90 MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
  91 MODULE_LICENSE("GPL");