hwmon: Add support for the sl28cpld hardware monitoring controller (3f697027) · Commits · jan.koester / Linux

Documentation/hwmon/index.rst

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		@@ -154,6 +154,7 @@ Hardware Monitoring Kernel Drivers
		sht3x
		shtc1
		sis5595
		sl28cpld
		smm665
		smsc47b397
		smsc47m192

Documentation/hwmon/sl28cpld.rst

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		.. SPDX-License-Identifier: GPL-2.0-only

		Kernel driver sl28cpld
		======================

		Supported chips:

		* Kontron sl28cpld

		Prefix: 'sl28cpld'

		Datasheet: not available

		Authors: Michael Walle <michael@walle.cc>

		Description
		-----------

		The sl28cpld is a board management controller which also exposes a hardware
		monitoring controller. At the moment this controller supports a single fan
		supervisor. In the future there might be other flavours and additional
		hardware monitoring might be supported.

		The fan supervisor has a 7 bit counter register and a counter period of 1
		second. If the 7 bit counter overflows, the supervisor will automatically
		switch to x8 mode to support a wider input range at the loss of
		granularity.

		Sysfs entries
		-------------

		The following attributes are supported.

		======================= ========================================================
		fan1_input Fan RPM. Assuming 2 pulses per revolution.
		======================= ========================================================

drivers/hwmon/Kconfig

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		@@ -1479,6 +1479,16 @@ config SENSORS_RASPBERRYPI_HWMON
		This driver can also be built as a module. If so, the module
		will be called raspberrypi-hwmon.

		config SENSORS_SL28CPLD
		tristate "Kontron sl28cpld hardware monitoring driver"
		depends on MFD_SL28CPLD \|\| COMPILE_TEST
		help
		If you say yes here you get support for the fan supervisor of the
		sl28cpld board management controller.

		This driver can also be built as a module. If so, the module
		will be called sl28cpld-hwmon.

		config SENSORS_SHT15
		tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
		depends on GPIOLIB \|\| COMPILE_TEST

drivers/hwmon/Makefile

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		@@ -159,6 +159,7 @@ obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o
		obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
		obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
		obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o
		obj-$(CONFIG_SENSORS_SL28CPLD) += sl28cpld-hwmon.o
		obj-$(CONFIG_SENSORS_SHT15) += sht15.o
		obj-$(CONFIG_SENSORS_SHT21) += sht21.o
		obj-$(CONFIG_SENSORS_SHT3x) += sht3x.o

drivers/hwmon/sl28cpld-hwmon.c

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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 asssume 2 pulses per revolution.
		*/
		value *= 60 / 2;

		break;
		default:
		return -EOPNOTSUPP;
		}

		*input = value;
		return 0;
		}

		static const u32 sl28cpld_hwmon_fan_config[] = {
		HWMON_F_INPUT,
		0
		};

		static const struct hwmon_channel_info sl28cpld_hwmon_fan = {
		.type = hwmon_fan,
		.config = sl28cpld_hwmon_fan_config,
		};

		static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
		&sl28cpld_hwmon_fan,
		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");