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
 21struct sl28cpld_hwmon {
 22	struct regmap *regmap;
 23	u32 offset;
 24};
 25
 26static 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
 33static 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
 70static const u32 sl28cpld_hwmon_fan_config[] = {
 71	HWMON_F_INPUT,
 72	0
 73};
 74
 75static const struct hwmon_channel_info sl28cpld_hwmon_fan = {
 76	.type = hwmon_fan,
 77	.config = sl28cpld_hwmon_fan_config,
 78};
 79
 80static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
 81	&sl28cpld_hwmon_fan,
 82	NULL
 83};
 84
 85static const struct hwmon_ops sl28cpld_hwmon_ops = {
 86	.is_visible = sl28cpld_hwmon_is_visible,
 87	.read = sl28cpld_hwmon_read,
 88};
 89
 90static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
 91	.ops = &sl28cpld_hwmon_ops,
 92	.info = sl28cpld_hwmon_info,
 93};
 94
 95static 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
125static const struct of_device_id sl28cpld_hwmon_of_match[] = {
126	{ .compatible = "kontron,sl28cpld-fan" },
127	{}
128};
129MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
130
131static 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};
138module_platform_driver(sl28cpld_hwmon_driver);
139
140MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
141MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
142MODULE_LICENSE("GPL");