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 <ivor@iwanders.net>
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
16SSAM_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
22static 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
29static 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
46static const struct hwmon_channel_info *const surface_fan_info[] = {
47	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
48	NULL
49};
50
51static const struct hwmon_ops surface_fan_hwmon_ops = {
52	.is_visible = surface_fan_hwmon_is_visible,
53	.read = surface_fan_hwmon_read,
54};
55
56static const struct hwmon_chip_info surface_fan_chip_info = {
57	.ops = &surface_fan_hwmon_ops,
58	.info = surface_fan_info,
59};
60
61static 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
73static const struct ssam_device_id ssam_fan_match[] = {
74	{ SSAM_SDEV(FAN, SAM, 0x01, 0x01) },
75	{},
76};
77MODULE_DEVICE_TABLE(ssam, ssam_fan_match);
78
79static 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};
87module_ssam_device_driver(surface_fan);
88
89MODULE_AUTHOR("Ivor Wanders <ivor@iwanders.net>");
90MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
91MODULE_LICENSE("GPL");
92