Re: [PATCH v4 1/2] thermal: add support for the MCU controlled FAN on Khadas boards

[Neil Armstrong <narmstrong@baylibre.com>]

Hi Daniel,

On 22/06/2020 21:46, Daniel Lezcano wrote:
> On 18/06/2020 15:38, 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 thermal devices and as cell of the Khadas
>> MCU MFD driver.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
>> ---
>> Hi Lee,
>>
>> Could you apply this patch via the MFD tree since it depends on
>> the linux/mfd/khadas-mcu.h header ?
>>
>> This patch is unchanged from the v3 serie.
>>
>> Thanks,
>> Neil
>>
>>  drivers/thermal/Kconfig          |  11 ++
>>  drivers/thermal/Makefile         |   1 +
>>  drivers/thermal/khadas_mcu_fan.c | 174 +++++++++++++++++++++++++++++++
>>  3 files changed, 186 insertions(+)
>>  create mode 100644 drivers/thermal/khadas_mcu_fan.c
>>
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index 3eb2348e5242..0125561488c9 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -500,4 +500,15 @@ config SPRD_THERMAL
>>  	help
>>  	  Support for the Spreadtrum thermal sensor driver in the Linux thermal
>>  	  framework.
>> +
>> +config KHADAS_MCU_FAN_THERMAL
>> +	tristate "Khadas MCU controller FAN cooling support"
>> +	depends on OF || COMPILE_TEST
>> +	depends on MFD_KHADAS_MCU
>> +	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.
>> +
>>  endif
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index 0c8b84a09b9a..4b6aabaa7e31 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -61,3 +61,4 @@ obj-$(CONFIG_ZX2967_THERMAL)	+= zx2967_thermal.o
>>  obj-$(CONFIG_UNIPHIER_THERMAL)	+= uniphier_thermal.o
>>  obj-$(CONFIG_AMLOGIC_THERMAL)     += amlogic_thermal.o
>>  obj-$(CONFIG_SPRD_THERMAL)	+= sprd_thermal.o
>> +obj-$(CONFIG_KHADAS_MCU_FAN_THERMAL)	+= khadas_mcu_fan.o
>> diff --git a/drivers/thermal/khadas_mcu_fan.c b/drivers/thermal/khadas_mcu_fan.c
>> new file mode 100644
>> index 000000000000..6995b443cad4
>> --- /dev/null
>> +++ b/drivers/thermal/khadas_mcu_fan.c
>> @@ -0,0 +1,174 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Khadas MCU Controlled FAN driver
>> + *
>> + * Copyright (C) 2020 BayLibre SAS
>> + * Author(s): Neil Armstrong <narmstrong@baylibre.com>
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.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->regmap, KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
>> +			   level);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ctx->level = level;
>> +
>> +	return 0;
>> +}
>> +
>> +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;
> 
> It is pointless to check 'ctx' is NULL, that was done at probe time.
> 
>> +	*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;
> 
> Ditto
> 
>> +	*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;
> 
> Ditto

Will remove these.

> 
>> +	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;
>> +	int ret;
>> +
>> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>> +	if (!ctx)
>> +		return -ENOMEM;
>> +	ctx->mcu = mcu;
>> +	platform_set_drvdata(pdev, ctx);
>> +
>> +	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;
> 
> Nitpicking : move the save section to suspend.

OK, but moving this makes khadas_mcu_fan_disable() useless.

> 
>> +	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);
> 
> Out of curiosity, did you check the fan is not continuously spinning
> after a resume when the suspend happened during a mitigation phase?

No, but I took the logic from the hmwmon pwm-fan driver.

Not sure this is critical here.

Neil

> 
>> +}
>> +#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@baylibre.com>");
>> +MODULE_DESCRIPTION("Khadas MCU FAN driver");
>> +MODULE_LICENSE("GPL");
>>
> 
>