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

[Daniel Lezcano <daniel.lezcano@linaro.org>]

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

> +	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.

> +	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?

> +}
> +#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");
> 


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