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// SPDX-License-Identifier: GPL-2.0-only
/*
* sl28cpld hardware monitoring driver
*
* Copyright 2020 Kontron Europe GmbH
*/
#include <linux/bitfield.h>
#include <linux/hwmon.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#define FAN_INPUT 0x00
#define FAN_SCALE_X8 BIT(7)
#define FAN_VALUE_MASK GENMASK(6, 0)
struct sl28cpld_hwmon {
struct regmap *regmap;
u32 offset;
};
static umode_t sl28cpld_hwmon_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
return 0444;
}
static int sl28cpld_hwmon_read(struct device *dev,
enum hwmon_sensor_types type, u32 attr,
int channel, long *input)
{
struct sl28cpld_hwmon *hwmon = dev_get_drvdata(dev);
unsigned int value;
int ret;
switch (attr) {
case hwmon_fan_input:
ret = regmap_read(hwmon->regmap, hwmon->offset + FAN_INPUT,
&value);
if (ret)
return ret;
/*
* The register has a 7 bit value and 1 bit which indicates the
* scale. If the MSB is set, then the lower 7 bit has to be
* multiplied by 8, to get the correct reading.
*/
if (value & FAN_SCALE_X8)
value = FIELD_GET(FAN_VALUE_MASK, value) << 3;
/*
* The counter period is 1000ms and the sysfs specification
* says we should assume 2 pulses per revolution.
*/
value *= 60 / 2;
break;
default:
return -EOPNOTSUPP;
}
*input = value;
return 0;
}
static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
NULL
};
static const struct hwmon_ops sl28cpld_hwmon_ops = {
.is_visible = sl28cpld_hwmon_is_visible,
.read = sl28cpld_hwmon_read,
};
static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
.ops = &sl28cpld_hwmon_ops,
.info = sl28cpld_hwmon_info,
};
static int sl28cpld_hwmon_probe(struct platform_device *pdev)
{
struct sl28cpld_hwmon *hwmon;
struct device *hwmon_dev;
int ret;
if (!pdev->dev.parent)
return -ENODEV;
hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
if (!hwmon)
return -ENOMEM;
hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
if (!hwmon->regmap)
return -ENODEV;
ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset);
if (ret)
return -EINVAL;
hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
"sl28cpld_hwmon", hwmon,
&sl28cpld_hwmon_chip_info, NULL);
if (IS_ERR(hwmon_dev))
dev_err(&pdev->dev, "failed to register as hwmon device");
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct of_device_id sl28cpld_hwmon_of_match[] = {
{ .compatible = "kontron,sl28cpld-fan" },
{}
};
MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
static struct platform_driver sl28cpld_hwmon_driver = {
.probe = sl28cpld_hwmon_probe,
.driver = {
.name = "sl28cpld-fan",
.of_match_table = sl28cpld_hwmon_of_match,
},
};
module_platform_driver(sl28cpld_hwmon_driver);
MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
MODULE_LICENSE("GPL");
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