Re: [RFC 3/8] hwmon: add support for the MCU controlled FAN on Khadas boards

[Neil Armstrong]

On 21/04/2020 11:24, Guenter Roeck wrote:
> On 4/21/20 1:00 AM, Neil Armstrong wrote:
>> The new Khadas VIM2 and VIM3 boards controls the cooling fan via the
>> on-board microcontroller.
>>
>> This implements the FAN control as HWMON devices as cell of the Khadas
>> MCU MFD driver.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> 
> This should be a thermal driver, not a hwmon driver.
> I don't see a single standard hwmon attribute, making
> the driver quite pointless as hwmon device.

Sure,

Neil

> 
> Guenter
> 
>> ---
>>  drivers/hwmon/Kconfig          |   9 ++
>>  drivers/hwmon/Makefile         |   1 +
>>  drivers/hwmon/khadas-mcu-fan.c | 230 +++++++++++++++++++++++++++++++++
>>  3 files changed, 240 insertions(+)
>>  create mode 100644 drivers/hwmon/khadas-mcu-fan.c
>>
>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>> index 4c62f900bf7e..7f63ff7bb732 100644
>> --- a/drivers/hwmon/Kconfig
>> +++ b/drivers/hwmon/Kconfig
>> @@ -1997,6 +1997,15 @@ config SENSORS_XGENE
>>  	  If you say yes here you get support for the temperature
>>  	  and power sensors for APM X-Gene SoC.
>>  
>> +config SENSORS_KHADAS_MCU_FAN
>> +	tristate "Khadas MCU controller FAN driver"
>> +	depends on OF || COMPILE_TEST
>> +	select MFD_CORE
>> +	select REGMAP
>> +	help
>> +	  If you say yes here you get support for the FAN controlled
>> +	  by the Microcontroller found on the Khadas VIM boards.
>> +
>>  if ACPI
>>  
>>  comment "ACPI drivers"
>> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
>> index b0b9c8e57176..20db40f6d57f 100644
>> --- a/drivers/hwmon/Makefile
>> +++ b/drivers/hwmon/Makefile
>> @@ -185,6 +185,7 @@ obj-$(CONFIG_SENSORS_W83L786NG)	+= w83l786ng.o
>>  obj-$(CONFIG_SENSORS_WM831X)	+= wm831x-hwmon.o
>>  obj-$(CONFIG_SENSORS_WM8350)	+= wm8350-hwmon.o
>>  obj-$(CONFIG_SENSORS_XGENE)	+= xgene-hwmon.o
>> +obj-$(CONFIG_SENSORS_KHADAS_MCU_FAN)	+= khadas-mcu-fan.o
>>  
>>  obj-$(CONFIG_SENSORS_OCC)	+= occ/
>>  obj-$(CONFIG_PMBUS)		+= pmbus/
>> diff --git a/drivers/hwmon/khadas-mcu-fan.c b/drivers/hwmon/khadas-mcu-fan.c
>> new file mode 100644
>> index 000000000000..dd92b2bcb7e3
>> --- /dev/null
>> +++ b/drivers/hwmon/khadas-mcu-fan.c
>> @@ -0,0 +1,230 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Khadas MCU Controlled FAN driver
>> + *
>> + * Copyright (C) 2020 BayLibre SAS
>> + * Author(s): Neil Armstrong <narmstrong@xxxxxxxxxxxx>
>> + */
>> +
>> +#include <linux/hwmon.h>
>> +#include <linux/hwmon-sysfs.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/mfd/khadas-mcu.h>
>> +#include <linux/regmap.h>
>> +#include <linux/sysfs.h>
>> +#include <linux/thermal.h>
>> +
>> +#define MAX_LEVEL 3
>> +
>> +struct khadas_mcu_fan_ctx {
>> +	struct khadas_mcu *mcu;
>> +	unsigned int level;
>> +	struct thermal_cooling_device *cdev;
>> +};
>> +
>> +static int khadas_mcu_fan_set_level(struct khadas_mcu_fan_ctx *ctx,
>> +				    unsigned int level)
>> +{
>> +	int ret;
>> +
>> +	ret = regmap_write(ctx->mcu->map, KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
>> +			   level);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ctx->level = level;
>> +
>> +	return 0;
>> +}
>> +
>> +static ssize_t level_store(struct device *dev, struct device_attribute *attr,
>> +			   const char *buf, size_t count)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
>> +	unsigned long level;
>> +	int ret;
>> +
>> +	if (kstrtoul(buf, 10, &level) || level > MAX_LEVEL)
>> +		return -EINVAL;
>> +
>> +	ret = khadas_mcu_fan_set_level(ctx, level);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return count;
>> +}
>> +
>> +static ssize_t level_show(struct device *dev, struct device_attribute *attr,
>> +			  char *buf)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
>> +
>> +	return sprintf(buf, "%u\n", ctx->level);
>> +}
>> +
>> +static SENSOR_DEVICE_ATTR_RW(level1, level, 0);
>> +
>> +static struct attribute *khadas_mcu_fan_attrs[] = {
>> +	&sensor_dev_attr_level1.dev_attr.attr,
>> +	NULL,
>> +};
>> +
>> +static const struct attribute_group khadas_mcu_fan_group = {
>> +	.attrs = khadas_mcu_fan_attrs,
>> +};
>> +
>> +static const struct attribute_group *khadas_mcu_fan_groups[] = {
>> +	&khadas_mcu_fan_group,
>> +	NULL,
>> +};
>> +
>> +/* thermal cooling device callbacks */
>> +static int khadas_mcu_fan_get_max_state(struct thermal_cooling_device *cdev,
>> +					unsigned long *state)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
>> +
>> +	if (!ctx)
>> +		return -EINVAL;
>> +
>> +	*state = MAX_LEVEL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int khadas_mcu_fan_get_cur_state(struct thermal_cooling_device *cdev,
>> +					unsigned long *state)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
>> +
>> +	if (!ctx)
>> +		return -EINVAL;
>> +
>> +	*state = ctx->level;
>> +
>> +	return 0;
>> +}
>> +
>> +static int
>> +khadas_mcu_fan_set_cur_state(struct thermal_cooling_device *cdev,
>> +			     unsigned long state)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
>> +
>> +	if (!ctx || (state > MAX_LEVEL))
>> +		return -EINVAL;
>> +
>> +	if (state == ctx->level)
>> +		return 0;
>> +
>> +	return khadas_mcu_fan_set_level(ctx, state);
>> +}
>> +
>> +static const struct thermal_cooling_device_ops khadas_mcu_fan_cooling_ops = {
>> +	.get_max_state = khadas_mcu_fan_get_max_state,
>> +	.get_cur_state = khadas_mcu_fan_get_cur_state,
>> +	.set_cur_state = khadas_mcu_fan_set_cur_state,
>> +};
>> +
>> +static int khadas_mcu_fan_probe(struct platform_device *pdev)
>> +{
>> +	struct khadas_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
>> +	struct thermal_cooling_device *cdev;
>> +	struct device *dev = &pdev->dev;
>> +	struct khadas_mcu_fan_ctx *ctx;
>> +	struct device *hwmon;
>> +	int ret;
>> +
>> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>> +	if (!ctx)
>> +		return -ENOMEM;
>> +	ctx->mcu = mcu;
>> +	platform_set_drvdata(pdev, ctx);
>> +
>> +	hwmon = devm_hwmon_device_register_with_groups(dev, "khadas-mcu-fan",
>> +						       ctx,
>> +						       khadas_mcu_fan_groups);
>> +	if (IS_ERR(hwmon)) {
>> +		dev_err(dev, "Failed to register hwmon device\n");
>> +		return PTR_ERR(hwmon);
>> +	}
>> +
>> +	if (IS_ENABLED(CONFIG_THERMAL)) {
>> +		cdev = devm_thermal_of_cooling_device_register(dev->parent,
>> +			dev->parent->of_node, "khadas-mcu-fan", ctx,
>> +			&khadas_mcu_fan_cooling_ops);
>> +		if (IS_ERR(cdev)) {
>> +			ret = PTR_ERR(cdev);
>> +			dev_err(dev,
>> +				"Failed to register khadas-mcu-fan as cooling device: %d\n",
>> +				ret);
>> +			return ret;
>> +		}
>> +		ctx->cdev = cdev;
>> +		thermal_cdev_update(cdev);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int khadas_mcu_fan_disable(struct device *dev)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
>> +	unsigned int level_save = ctx->level;
>> +	int ret;
>> +
>> +	ret = khadas_mcu_fan_set_level(ctx, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ctx->level = level_save;
>> +
>> +	return 0;
>> +}
>> +
>> +static void khadas_mcu_fan_shutdown(struct platform_device *pdev)
>> +{
>> +	khadas_mcu_fan_disable(&pdev->dev);
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int khadas_mcu_fan_suspend(struct device *dev)
>> +{
>> +	return khadas_mcu_fan_disable(dev);
>> +}
>> +
>> +static int khadas_mcu_fan_resume(struct device *dev)
>> +{
>> +	struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
>> +
>> +	return khadas_mcu_fan_set_level(ctx, ctx->level);
>> +}
>> +#endif
>> +
>> +static SIMPLE_DEV_PM_OPS(khadas_mcu_fan_pm, khadas_mcu_fan_suspend,
>> +			 khadas_mcu_fan_resume);
>> +
>> +static const struct platform_device_id khadas_mcu_fan_id_table[] = {
>> +	{ .name = "khadas-mcu-fan-ctrl", },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(platform, khadas_mcu_fan_id_table);
>> +
>> +static struct platform_driver khadas_mcu_fan_driver = {
>> +	.probe		= khadas_mcu_fan_probe,
>> +	.shutdown	= khadas_mcu_fan_shutdown,
>> +	.driver	= {
>> +		.name		= "khadas-mcu-fan-ctrl",
>> +		.pm		= &khadas_mcu_fan_pm,
>> +	},
>> +	.id_table	= khadas_mcu_fan_id_table,
>> +};
>> +
>> +module_platform_driver(khadas_mcu_fan_driver);
>> +
>> +MODULE_AUTHOR("Neil Armstrong <narmstrong@xxxxxxxxxxxx>");
>> +MODULE_DESCRIPTION("Khadas MCU FAN driver");
>> +MODULE_LICENSE("GPL");
>>
>