Re: [PATCH v4 5/8] thermal: khadas-mcu-fan: Add fan config from platform data Add regulator support

[Neil Armstrong <neil.armstrong@linaro.org>]

On 4/21/26 13:49, Ronald Claveau via B4 Relay wrote:
> From: Ronald Claveau <linux-kernel-dev@aliel.fr>
> 
> Replace the hardcoded MAX_LEVEL constant and fan register
> with values read from platform_data (fan_reg, max_level),
> as new MCUs need different values.
> 
> Optionally acquire and enable a "fan" regulator supply
> at probe time and on resume,
> so boards that gate fan power through a regulator are handled.
> 
> Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
> ---
>   drivers/thermal/khadas_mcu_fan.c | 49 +++++++++++++++++++++++++++++++++++-----
>   1 file changed, 43 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/thermal/khadas_mcu_fan.c b/drivers/thermal/khadas_mcu_fan.c
> index d35e5313bea41..24559bf65de46 100644
> --- a/drivers/thermal/khadas_mcu_fan.c
> +++ b/drivers/thermal/khadas_mcu_fan.c
> @@ -13,13 +13,15 @@
>   #include <linux/regmap.h>
>   #include <linux/sysfs.h>
>   #include <linux/thermal.h>
> -
> -#define MAX_LEVEL 3
> +#include <linux/regulator/consumer.h>
>   
>   struct khadas_mcu_fan_ctx {
>   	struct khadas_mcu *mcu;
> +	unsigned int fan_reg;
>   	unsigned int level;
> +	unsigned int max_level;
>   	struct thermal_cooling_device *cdev;
> +	struct regulator *power;
>   };
>   
>   static int khadas_mcu_fan_set_level(struct khadas_mcu_fan_ctx *ctx,
> @@ -27,8 +29,7 @@ static int khadas_mcu_fan_set_level(struct khadas_mcu_fan_ctx *ctx,
>   {
>   	int ret;
>   
> -	ret = regmap_write(ctx->mcu->regmap, KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
> -			   level);
> +	ret = regmap_write(ctx->mcu->regmap, ctx->fan_reg, level);
>   	if (ret)
>   		return ret;
>   
> @@ -40,7 +41,9 @@ static int khadas_mcu_fan_set_level(struct khadas_mcu_fan_ctx *ctx,
>   static int khadas_mcu_fan_get_max_state(struct thermal_cooling_device *cdev,
>   					unsigned long *state)
>   {
> -	*state = MAX_LEVEL;
> +	struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
> +
> +	*state = ctx->max_level;
>   
>   	return 0;
>   }
> @@ -61,7 +64,7 @@ khadas_mcu_fan_set_cur_state(struct thermal_cooling_device *cdev,
>   {
>   	struct khadas_mcu_fan_ctx *ctx = cdev->devdata;
>   
> -	if (state > MAX_LEVEL)
> +	if (state > ctx->max_level)
>   		return -EINVAL;
>   
>   	if (state == ctx->level)
> @@ -83,11 +86,32 @@ static int khadas_mcu_fan_probe(struct platform_device *pdev)
>   	struct device *dev = &pdev->dev;
>   	struct khadas_mcu_fan_ctx *ctx;
>   	int ret;
> +	const struct khadas_mcu_fan_pdata *pdata = dev_get_platdata(&pdev->dev);

Move this on top to respect reverse christmas ordering.

>   
>   	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>   	if (!ctx)
>   		return -ENOMEM;
> +
>   	ctx->mcu = mcu;
> +	ctx->fan_reg   = pdata->fan_reg;
> +	ctx->max_level = pdata->max_level;
> +
> +	ctx->power = devm_regulator_get_optional(dev->parent, "fan");
> +	if (IS_ERR(ctx->power)) {
> +		if (PTR_ERR(ctx->power) == -ENODEV)
> +			ctx->power = NULL;
> +		else
> +			return PTR_ERR(ctx->power);
> +	}
> +
> +	if (ctx->power) {
> +		ret = regulator_enable(ctx->power);
> +		if (ret) {
> +			dev_err(dev, "Failed to enable fan power supply: %d\n", ret);
> +			return ret; 
> +		}
> +	}

Or you can request with devm_regulator_get(dev->parent, "fan"); which will
return a dummy regulator, and then you can just call regulator_enable & disable
and remove all those checks.

> +
>   	platform_set_drvdata(pdev, ctx);
>   
>   	cdev = devm_thermal_of_cooling_device_register(dev->parent,
> @@ -124,12 +148,25 @@ static int khadas_mcu_fan_suspend(struct device *dev)
>   
>   	ctx->level = level_save;
>   
> +	if (ctx->power) {
> +		ret = regulator_disable(ctx->power);
> +		if (ret)
> +			return ret;
> +	}

if (ctx->power)
	return regulator_disable(ctx->power);

> +
>   	return 0;
>   }
>   
>   static int khadas_mcu_fan_resume(struct device *dev)
>   {
>   	struct khadas_mcu_fan_ctx *ctx = dev_get_drvdata(dev);
> +	int ret;
> +
> +	if (ctx->power) {
> +		ret = regulator_enable(ctx->power);
> +		if (ret)
> +			return ret;
> +	}
>   
>   	return khadas_mcu_fan_set_level(ctx, ctx->level);
>   }
> 

Thanks,
Neil