Message-ID: <fd1db8a4-9ea5-49b2-9316-65bf3753a7fa@roeck-us.net>
Date: Tue, 13 Aug 2024 09:03:57 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Heiko Stuebner <heiko@...ech.de>, lee@...nel.org, jdelvare@...e.com,
 dmitry.torokhov@...il.com, pavel@....cz
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 ukleinek@...ian.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-hwmon@...r.kernel.org,
 linux-input@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH v4 5/7] hwmon: add driver for the hwmon parts of qnap-mcu
 devices

On 8/10/24 11:47, Heiko Stuebner wrote:
> The MCU can be found on network-attached-storage devices made by QNAP
> and provides access to fan control including reading back its RPM as
> well as reading the temperature of the NAS case.
> 
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> ---
>   Documentation/hwmon/index.rst          |   1 +
>   Documentation/hwmon/qnap-mcu-hwmon.rst |  27 ++
>   MAINTAINERS                            |   1 +
>   drivers/hwmon/Kconfig                  |  12 +
>   drivers/hwmon/Makefile                 |   1 +
>   drivers/hwmon/qnap-mcu-hwmon.c         | 392 +++++++++++++++++++++++++
>   6 files changed, 434 insertions(+)
>   create mode 100644 Documentation/hwmon/qnap-mcu-hwmon.rst
>   create mode 100644 drivers/hwmon/qnap-mcu-hwmon.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 913c11390a457..7adbe23f06597 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -199,6 +199,7 @@ Hardware Monitoring Kernel Drivers
>      pxe1610
>      pwm-fan
>      q54sj108a2
> +   qnap-mcu-hwmon
>      raspberrypi-hwmon
>      sbrmi
>      sbtsi_temp
> diff --git a/Documentation/hwmon/qnap-mcu-hwmon.rst b/Documentation/hwmon/qnap-mcu-hwmon.rst
> new file mode 100644
> index 0000000000000..83407e3408f2b
> --- /dev/null
> +++ b/Documentation/hwmon/qnap-mcu-hwmon.rst
> @@ -0,0 +1,27 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver qnap-mcu-hwmon
> +============================
> +
> +This driver enables the use of the hardware monitoring and fan control
> +of the MCU used on some QNAP network attached storage devices.
> +
> +Author: Heiko Stuebner <heiko@...ech.de>
> +
> +Description
> +-----------
> +
> +The driver implements a simple interface for driving the fan controlled by
> +setting its PWM output value and exposes the fan rpm and case-temperature
> +to user space through hwmon's sysfs interface.
> +
> +The fan rotation speed returned via the optional 'fan1_input' is calculated
> +inside the MCU device.
> +
> +The driver provides the following sensor accesses in sysfs:
> +
> +=============== ======= =======================================================
> +fan1_input	ro	fan tachometer speed in RPM
> +pwm1		rw	relative speed (0-255), 255=max. speed.
> +temp1_input	ro	Measured temperature in millicelsius
> +=============== ======= =======================================================
> diff --git a/MAINTAINERS b/MAINTAINERS
> index baaec814bea1b..282042e3d5f80 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -18655,6 +18655,7 @@ F:	drivers/media/tuners/qm1d1c0042*
>   QNAP MCU DRIVER
>   M:	Heiko Stuebner <heiko@...ech.de>
>   S:	Maintained
> +F:	drivers/hwmon/qnap-mcu-hwmon.c
>   F:	drivers/input/misc/qnap-mcu-input.c
>   F:	drivers/leds/leds-qnap-mcu.c
>   F:	drivers/mfd/qnap-mcu.c
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index b60fe2e58ad6c..0118ad91057e0 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1793,6 +1793,18 @@ config SENSORS_PWM_FAN
>   	  This driver can also be built as a module. If so, the module
>   	  will be called pwm-fan.
>   
> +config SENSORS_QNAP_MCU_HWMON
> +	tristate "QNAP MCU hardware monitoring"
> +	depends on MFD_QNAP_MCU
> +	depends on THERMAL || THERMAL=n
> +	help
> +	  Say yes here to enable support for fan and temperature sensor
> +	  connected to a QNAP MCU, as found in a number of QNAP network
> +	  attached storage devices.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called qnap-mcu-hwmon.
> +
>   config SENSORS_RASPBERRYPI_HWMON
>   	tristate "Raspberry Pi voltage monitor"
>   	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index b1c7056c37db5..d60f46a03cc96 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -187,6 +187,7 @@ obj-$(CONFIG_SENSORS_POWERZ)	+= powerz.o
>   obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
>   obj-$(CONFIG_SENSORS_PT5161L)	+= pt5161l.o
>   obj-$(CONFIG_SENSORS_PWM_FAN)	+= pwm-fan.o
> +obj-$(CONFIG_SENSORS_QNAP_MCU_HWMON)	+= qnap-mcu-hwmon.o
>   obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)	+= raspberrypi-hwmon.o
>   obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi_temp.o
>   obj-$(CONFIG_SENSORS_SBRMI)	+= sbrmi.o
> diff --git a/drivers/hwmon/qnap-mcu-hwmon.c b/drivers/hwmon/qnap-mcu-hwmon.c
> new file mode 100644
> index 0000000000000..f106fe8b012ea
> --- /dev/null
> +++ b/drivers/hwmon/qnap-mcu-hwmon.c
> @@ -0,0 +1,392 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +/*
> + * Driver for hwmon elements found on QNAP-MCU devices
> + *
> + * Copyright (C) 2024 Heiko Stuebner <heiko@...ech.de>
> + */
> +
> +#include <linux/fwnode.h>
> +#include <linux/hwmon.h>
> +#include <linux/mfd/qnap-mcu.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/thermal.h>
> +
> +struct qnap_mcu_hwmon {
> +	struct qnap_mcu *mcu;
> +	struct device *dev;
> +
> +	unsigned int pwm_min;
> +	unsigned int pwm_max;
> +
> +	struct fwnode_handle *fan_node;
> +	unsigned int fan_state;
> +	unsigned int fan_max_state;
> +	unsigned int *fan_cooling_levels;
> +
> +	struct thermal_cooling_device *cdev;
> +	struct hwmon_chip_info info;
> +};
> +
> +static int qnap_mcu_hwmon_get_rpm(struct qnap_mcu_hwmon *hwm)
> +{
> +	static const u8 cmd[] = {
> +		[0] = 0x40, /* @ */
> +		[1] = 0x46, /* F */
> +		[2] = 0x41  /* A */
> +	};
> +	u8 reply[6];
> +	int ret;
> +
> +	/* poll the fan rpm */
> +	ret = qnap_mcu_exec(hwm->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
> +	if (ret)
> +		return ret;
> +
> +	/* First 2 bytes must mirror the sent command */
> +	if (memcmp(cmd, reply, 2))
> +		return -EIO;
> +
> +	return reply[4] * 30;
> +}
> +
> +static int qnap_mcu_hwmon_get_pwm(struct qnap_mcu_hwmon *hwm)
> +{
> +	static const u8 cmd[] = {
> +		[0] = 0x40, /* @ */
> +		[1] = 0x46, /* F */
> +		[2] = 0x5a, /* Z */
> +		[3] = 0x30  /* 0 ... fan-id? */
> +	};
> +	u8 reply[4];
> +	int ret;
> +
> +	/* poll the fan pwm */
> +	ret = qnap_mcu_exec(hwm->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
> +	if (ret)
> +		return ret;
> +
> +	/* First 3 bytes must mirror the sent command */
> +	if (memcmp(cmd, reply, 3))
> +		return -EIO;
> +
> +	return reply[3];
> +}
> +
> +static int qnap_mcu_hwmon_set_pwm(struct qnap_mcu_hwmon *hwm, u8 pwm)
> +{
> +	const u8 cmd[] = {
> +		[0] = 0x40, /* @ */
> +		[1] = 0x46, /* F */
> +		[2] = 0x57, /* W */
> +		[3] = 0x30, /* 0 ... fan-id? */
> +		[4] = pwm
> +	};
> +
> +	/* set the fan pwm */
> +	return qnap_mcu_exec_with_ack(hwm->mcu, cmd, sizeof(cmd));
> +}
> +
> +static int qnap_mcu_hwmon_get_temp(struct qnap_mcu_hwmon *hwm)
> +{
> +	static const u8 cmd[] = {
> +		[0] = 0x40, /* @ */
> +		[1] = 0x54, /* T */
> +		[2] = 0x33  /* 3 */
> +	};
> +	u8 reply[4];
> +	int ret;
> +
> +	/* poll the fan rpm */
> +	ret = qnap_mcu_exec(hwm->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
> +	if (ret)
> +		return ret;
> +
> +	/* First bytes must mirror the sent command */
> +	if (memcmp(cmd, reply, sizeof(cmd)))
> +		return -EIO;
> +
> +	/*
> +	 * There is an unknown bit set in bit7.
> +	 * Bits [6:0] report the actual temperature as returned by the
> +	 * original qnap firmware-tools, so just drop bit7 for now.
> +	 */
> +	return (reply[3] & 0x7f) * 1000;
> +}
> +
> +static int qnap_mcu_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
> +				u32 attr, int channel, long val)
> +{
> +	struct qnap_mcu_hwmon *hwm = dev_get_drvdata(dev);
> +
> +	switch (attr) {
> +	case hwmon_pwm_input:
> +		if (val < 0 || val > 255)
> +			return -EINVAL;
> +
> +		if (val != 0)
> +			val = clamp_val(val, hwm->pwm_min, hwm->pwm_max);
> +
> +		return qnap_mcu_hwmon_set_pwm(hwm, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int qnap_mcu_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +			       u32 attr, int channel, long *val)
> +{
> +	struct qnap_mcu_hwmon *hwm = dev_get_drvdata(dev);
> +	int ret;
> +
> +	switch (type) {
> +	case hwmon_pwm:
> +		switch (attr) {
> +		case hwmon_pwm_input:
> +			ret = qnap_mcu_hwmon_get_pwm(hwm);
> +			if (ret < 0)
> +				return ret;
> +
> +			*val = ret;
> +			return 0;
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +	case hwmon_fan:
> +		ret = qnap_mcu_hwmon_get_rpm(hwm);
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = ret;
> +		return 0;
> +	case hwmon_temp:
> +		ret = qnap_mcu_hwmon_get_temp(hwm);
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = ret;
> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static umode_t qnap_mcu_hwmon_is_visible(const void *data,
> +					 enum hwmon_sensor_types type,
> +					 u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_temp:
> +		return 0444;
> +
> +	case hwmon_pwm:
> +		return 0644;
> +
> +	case hwmon_fan:
> +		return 0444;
> +
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static const struct hwmon_ops qnap_mcu_hwmon_hwmon_ops = {
> +	.is_visible = qnap_mcu_hwmon_is_visible,
> +	.read = qnap_mcu_hwmon_read,
> +	.write = qnap_mcu_hwmon_write,
> +};
> +
> +/* thermal cooling device callbacks */
> +static int qnap_mcu_hwmon_get_max_state(struct thermal_cooling_device *cdev,
> +					unsigned long *state)
> +{
> +	struct qnap_mcu_hwmon *hwm = cdev->devdata;
> +
> +	if (!hwm)
> +		return -EINVAL;
> +
> +	*state = hwm->fan_max_state;
> +
> +	return 0;
> +}
> +
> +static int qnap_mcu_hwmon_get_cur_state(struct thermal_cooling_device *cdev,
> +					unsigned long *state)
> +{
> +	struct qnap_mcu_hwmon *hwm = cdev->devdata;
> +
> +	if (!hwm)
> +		return -EINVAL;
> +
> +	*state = hwm->fan_state;
> +
> +	return 0;
> +}
> +
> +static int qnap_mcu_hwmon_set_cur_state(struct thermal_cooling_device *cdev,
> +					unsigned long state)
> +{
> +	struct qnap_mcu_hwmon *hwm = cdev->devdata;
> +	int ret;
> +
> +	if (!hwm || state > hwm->fan_max_state)
> +		return -EINVAL;
> +
> +	if (state == hwm->fan_state)
> +		return 0;
> +
> +	ret = qnap_mcu_hwmon_set_pwm(hwm, hwm->fan_cooling_levels[state]);
> +	if (ret)
> +		return ret;
> +
> +	hwm->fan_state = state;
> +
> +	return ret;
> +}
> +
> +static const struct thermal_cooling_device_ops qnap_mcu_hwmon_cooling_ops = {
> +	.get_max_state = qnap_mcu_hwmon_get_max_state,
> +	.get_cur_state = qnap_mcu_hwmon_get_cur_state,
> +	.set_cur_state = qnap_mcu_hwmon_set_cur_state,
> +};
> +
> +static void devm_fan_node_release(void *data)
> +{
> +	struct qnap_mcu_hwmon *hwm = data;
> +
> +	fwnode_handle_put(hwm->fan_node);
> +}
> +
> +static int qnap_mcu_hwmon_get_cooling_data(struct device *dev, struct qnap_mcu_hwmon *hwm)
> +{
> +	struct fwnode_handle *fwnode;
> +	int num, i, ret;
> +
> +	fwnode = device_get_named_child_node(dev->parent, "fan-0");

Is the dummy "-0" index mandated somewhere ?

I don't care either way, it just seems odd. Either case,

Acked-by: Guenter Roeck <linux@...ck-us.net>

> +	if (!fwnode)
> +		return 0;
> +
> +	/* if we found the fan-node, we're keeping it until device-unbind */
> +	hwm->fan_node = fwnode;
> +	ret = devm_add_action_or_reset(dev, devm_fan_node_release, hwm);
> +	if (ret)
> +		return ret;
> +
> +	if (!fwnode_property_present(fwnode, "cooling-levels"))
> +		return 0;
> +

Side note: One could argue that a sub-node with no content does not really
make sense and should be invalid.

> +	ret = fwnode_property_count_u32(fwnode, "cooling-levels");
> +	if (ret <= 0) {
> +		dev_err(dev, "Failed to count elements in 'cooling-levels'\n");
> +		return ret ? : -EINVAL;
> +	}
> +
> +	num = ret;

Another side note: Using ret here isn't necessary. I'd just have used
'num' directly.

> +	hwm->fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
> +					       GFP_KERNEL);
> +	if (!hwm->fan_cooling_levels)
> +		return -ENOMEM;
> +
> +	ret = fwnode_property_read_u32_array(fwnode, "cooling-levels",
> +					     hwm->fan_cooling_levels, num);
> +	if (ret) {
> +		dev_err(dev, "Failed to read 'cooling-levels'\n");
> +		return ret;
> +	}
> +
> +	for (i = 0; i < num; i++) {
> +		if (hwm->fan_cooling_levels[i] > hwm->pwm_max) {
> +			dev_err(dev, "fan state[%d]:%d > %d\n", i,
> +				hwm->fan_cooling_levels[i], hwm->pwm_max);
> +			return -EINVAL;

In case you send another version, you might want to consider using dev_err_probe().

> +		}
> +	}
> +
> +	hwm->fan_max_state = num - 1;
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_channel_info * const qnap_mcu_hwmon_channels[] = {
> +	HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT),
> +	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
> +	NULL
> +};
> +
> +static int qnap_mcu_hwmon_probe(struct platform_device *pdev)
> +{
> +	struct qnap_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
> +	const struct qnap_mcu_variant *variant = qnap_mcu_get_variant_data(mcu);
> +	struct qnap_mcu_hwmon *hwm;
> +	struct thermal_cooling_device *cdev;
> +	struct device *dev = &pdev->dev;
> +	struct device *hwmon;
> +	int ret;
> +
> +	hwm = devm_kzalloc(dev, sizeof(*hwm), GFP_KERNEL);
> +	if (!hwm)
> +		return -ENOMEM;
> +
> +	hwm->mcu = mcu;
> +	hwm->dev = &pdev->dev;
> +	hwm->pwm_min = variant->fan_pwm_min;
> +	hwm->pwm_max = variant->fan_pwm_max;
> +
> +	platform_set_drvdata(pdev, hwm);
> +
> +	/*
> +	 * Set duty cycle to maximum allowed.
> +	 */
> +	ret = qnap_mcu_hwmon_set_pwm(hwm, hwm->pwm_max);
> +	if (ret)
> +		return ret;
> +
> +	hwm->info.ops = &qnap_mcu_hwmon_hwmon_ops;
> +	hwm->info.info = qnap_mcu_hwmon_channels;
> +
> +	ret = qnap_mcu_hwmon_get_cooling_data(dev, hwm);
> +	if (ret)
> +		return ret;
> +
> +	hwm->fan_state = hwm->fan_max_state;
> +
> +	hwmon = devm_hwmon_device_register_with_info(dev, "qnapmcu",
> +						     hwm, &hwm->info, NULL);
> +	if (IS_ERR(hwmon))
> +		return dev_err_probe(dev, PTR_ERR(hwmon), "Failed to register hwmon device\n");
> +
> +	/*
> +	 * Only register cooling device when we found cooling-levels.
> +	 * qnap_mcu_hwmon_get_cooling_data() will fail when reading malformed
> +	 * levels and only succeed with either no or correct cooling levels.
> +	 */
> +	if (IS_ENABLED(CONFIG_THERMAL) && hwm->fan_cooling_levels) {
> +		cdev = devm_thermal_of_cooling_device_register(dev,
> +					to_of_node(hwm->fan_node), "qnap-mcu-hwmon",
> +					hwm, &qnap_mcu_hwmon_cooling_ops);
> +		if (IS_ERR(cdev))
> +			return dev_err_probe(dev, PTR_ERR(cdev),
> +				"Failed to register qnap-mcu-hwmon as cooling device\n");
> +		hwm->cdev = cdev;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct platform_driver qnap_mcu_hwmon_driver = {
> +	.probe = qnap_mcu_hwmon_probe,
> +	.driver = {
> +		.name = "qnap-mcu-hwmon",
> +	},
> +};
> +module_platform_driver(qnap_mcu_hwmon_driver);
> +
> +MODULE_ALIAS("platform:qnap-mcu-hwmon");
> +MODULE_AUTHOR("Heiko Stuebner <heiko@...ech.de>");
> +MODULE_DESCRIPTION("QNAP MCU hwmon driver");
> +MODULE_LICENSE("GPL");

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