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