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(map: hwmon->regmap, reg: hwmon->offset + FAN_INPUT, |
44 | val: &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 assume 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 struct hwmon_channel_info * const sl28cpld_hwmon_info[] = { |
71 | HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT), |
72 | NULL |
73 | }; |
74 | |
75 | static const struct hwmon_ops sl28cpld_hwmon_ops = { |
76 | .is_visible = sl28cpld_hwmon_is_visible, |
77 | .read = sl28cpld_hwmon_read, |
78 | }; |
79 | |
80 | static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = { |
81 | .ops = &sl28cpld_hwmon_ops, |
82 | .info = sl28cpld_hwmon_info, |
83 | }; |
84 | |
85 | static int sl28cpld_hwmon_probe(struct platform_device *pdev) |
86 | { |
87 | struct sl28cpld_hwmon *hwmon; |
88 | struct device *hwmon_dev; |
89 | int ret; |
90 | |
91 | if (!pdev->dev.parent) |
92 | return -ENODEV; |
93 | |
94 | hwmon = devm_kzalloc(dev: &pdev->dev, size: sizeof(*hwmon), GFP_KERNEL); |
95 | if (!hwmon) |
96 | return -ENOMEM; |
97 | |
98 | hwmon->regmap = dev_get_regmap(dev: pdev->dev.parent, NULL); |
99 | if (!hwmon->regmap) |
100 | return -ENODEV; |
101 | |
102 | ret = device_property_read_u32(dev: &pdev->dev, propname: "reg" , val: &hwmon->offset); |
103 | if (ret) |
104 | return -EINVAL; |
105 | |
106 | hwmon_dev = devm_hwmon_device_register_with_info(dev: &pdev->dev, |
107 | name: "sl28cpld_hwmon" , drvdata: hwmon, |
108 | info: &sl28cpld_hwmon_chip_info, NULL); |
109 | if (IS_ERR(ptr: hwmon_dev)) |
110 | dev_err(&pdev->dev, "failed to register as hwmon device" ); |
111 | |
112 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
113 | } |
114 | |
115 | static const struct of_device_id sl28cpld_hwmon_of_match[] = { |
116 | { .compatible = "kontron,sl28cpld-fan" }, |
117 | {} |
118 | }; |
119 | MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match); |
120 | |
121 | static struct platform_driver sl28cpld_hwmon_driver = { |
122 | .probe = sl28cpld_hwmon_probe, |
123 | .driver = { |
124 | .name = "sl28cpld-fan" , |
125 | .of_match_table = sl28cpld_hwmon_of_match, |
126 | }, |
127 | }; |
128 | module_platform_driver(sl28cpld_hwmon_driver); |
129 | |
130 | MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver" ); |
131 | MODULE_AUTHOR("Michael Walle <michael@walle.cc>" ); |
132 | MODULE_LICENSE("GPL" ); |
133 | |