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
21static 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
38static const struct hwmon_channel_info *const surface_fan_info[] = {
39	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
40	NULL
41};
42
43static const struct hwmon_ops surface_fan_hwmon_ops = {
44	.visible = 0444,
45	.read = surface_fan_hwmon_read,
46};
47
48static const struct hwmon_chip_info surface_fan_chip_info = {
49	.ops = &surface_fan_hwmon_ops,
50	.info = surface_fan_info,
51};
52
53static 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
65static const struct ssam_device_id ssam_fan_match[] = {
66	{ SSAM_SDEV(FAN, SAM, 0x01, 0x01) },
67	{},
68};
69MODULE_DEVICE_TABLE(ssam, ssam_fan_match);
70
71static 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};
79module_ssam_device_driver(surface_fan);
80
81MODULE_AUTHOR("Ivor Wanders <ivor@iwanders.net>");
82MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
83MODULE_LICENSE("GPL");