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
sl28cpld_hwmon_is_visible(const void * data,enum hwmon_sensor_types type,u32 attr,int channel)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
sl28cpld_hwmon_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * input)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(hwmon->regmap, hwmon->offset + FAN_INPUT,
44 &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 asssume 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 u32 sl28cpld_hwmon_fan_config[] = {
71 HWMON_F_INPUT,
72 0
73 };
74
75 static const struct hwmon_channel_info sl28cpld_hwmon_fan = {
76 .type = hwmon_fan,
77 .config = sl28cpld_hwmon_fan_config,
78 };
79
80 static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
81 &sl28cpld_hwmon_fan,
82 NULL
83 };
84
85 static const struct hwmon_ops sl28cpld_hwmon_ops = {
86 .is_visible = sl28cpld_hwmon_is_visible,
87 .read = sl28cpld_hwmon_read,
88 };
89
90 static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
91 .ops = &sl28cpld_hwmon_ops,
92 .info = sl28cpld_hwmon_info,
93 };
94
sl28cpld_hwmon_probe(struct platform_device * pdev)95 static int sl28cpld_hwmon_probe(struct platform_device *pdev)
96 {
97 struct sl28cpld_hwmon *hwmon;
98 struct device *hwmon_dev;
99 int ret;
100
101 if (!pdev->dev.parent)
102 return -ENODEV;
103
104 hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
105 if (!hwmon)
106 return -ENOMEM;
107
108 hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
109 if (!hwmon->regmap)
110 return -ENODEV;
111
112 ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset);
113 if (ret)
114 return -EINVAL;
115
116 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
117 "sl28cpld_hwmon", hwmon,
118 &sl28cpld_hwmon_chip_info, NULL);
119 if (IS_ERR(hwmon_dev))
120 dev_err(&pdev->dev, "failed to register as hwmon device");
121
122 return PTR_ERR_OR_ZERO(hwmon_dev);
123 }
124
125 static const struct of_device_id sl28cpld_hwmon_of_match[] = {
126 { .compatible = "kontron,sl28cpld-fan" },
127 {}
128 };
129 MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
130
131 static struct platform_driver sl28cpld_hwmon_driver = {
132 .probe = sl28cpld_hwmon_probe,
133 .driver = {
134 .name = "sl28cpld-fan",
135 .of_match_table = sl28cpld_hwmon_of_match,
136 },
137 };
138 module_platform_driver(sl28cpld_hwmon_driver);
139
140 MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
141 MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
142 MODULE_LICENSE("GPL");
143
