Re: [PATCH 4/5] thermal: khadas_mcu_fan: add support for Khadas Edge 2

[neil.armstrong@linaro.org]

On 26/06/2025 16:04, muhammed.efecetin.67@gmail.com wrote:
> From: Muhammed Efe Cetin <efectn@protonmail.com>
> 
> Fan control on the Khadas Edge 2 is controlled with the 0x8A register,
> using percentage values from 0 to 100, whereas there are only 3 constant steps in previous Khadas boards.
> Therefore, i added a new cooling-levels property, similar to the one used in the pwm-fan driver.
> The original behavior can still be used when the cooling-levels property is not specified,
> ensuring that the new functionality does not break old boards.

Thanks for the explanation, but would would you like to change that ? The MCU can accept
any value between 0 and 99, so why change the levels from DT ?

Neil

> 
> Signed-off-by: Muhammed Efe Cetin <efectn@protonmail.com>
> ---
>   drivers/thermal/khadas_mcu_fan.c | 76 ++++++++++++++++++++++++++++++--
>   1 file changed, 72 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/thermal/khadas_mcu_fan.c b/drivers/thermal/khadas_mcu_fan.c
> index d35e5313b..504e7d254 100644
> --- a/drivers/thermal/khadas_mcu_fan.c
> +++ b/drivers/thermal/khadas_mcu_fan.c
> @@ -15,10 +15,16 @@
>   #include <linux/thermal.h>
>   
>   #define MAX_LEVEL 3
> +#define MAX_SPEED 0x64
>   
>   struct khadas_mcu_fan_ctx {
>   	struct khadas_mcu *mcu;
>   	unsigned int level;
> +
> +	unsigned int fan_max_level;
> +	unsigned int fan_register;
> +	unsigned int *fan_cooling_levels;
> +
>   	struct thermal_cooling_device *cdev;
>   };
>   
> @@ -26,9 +32,21 @@ static int khadas_mcu_fan_set_level(struct khadas_mcu_fan_ctx *ctx,
>   				    unsigned int level)
>   {
>   	int ret;
> +	unsigned int write_level = level;
> +
> +	if (level > ctx->fan_max_level)
> +		return -EINVAL;
> +
> +	if (ctx->fan_cooling_levels != NULL) {
> +		write_level = ctx->fan_cooling_levels[level];
> +
> +		if (write_level > MAX_SPEED)
> +			return -EINVAL;
> +	}
> +
> +	ret = regmap_write(ctx->mcu->regmap, ctx->fan_register,
> +			   write_level);
>   
> -	ret = regmap_write(ctx->mcu->regmap, KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
> -			   level);
>   	if (ret)
>   		return ret;
>   
> @@ -40,7 +58,9 @@ 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->fan_max_level;
>   
>   	return 0;
>   }
> @@ -61,7 +81,7 @@ 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->fan_max_level)
>   		return -EINVAL;
>   
>   	if (state == ctx->level)
> @@ -76,6 +96,47 @@ static const struct thermal_cooling_device_ops khadas_mcu_fan_cooling_ops = {
>   	.set_cur_state = khadas_mcu_fan_set_cur_state,
>   };
>   
> +static int khadas_mcu_fan_get_cooling_data_edge2(struct khadas_mcu_fan_ctx *ctx, struct device *dev)
> +{
> +	struct device_node *np = ctx->mcu->dev->of_node;
> +	int num, i, ret;
> +
> +	if (!of_property_present(np, "cooling-levels"))
> +		return 0;
> +
> +	ret = of_property_count_u32_elems(np, "cooling-levels");
> +	if (ret <= 0) {
> +		dev_err(dev, "Wrong data!\n");
> +		return ret ? : -EINVAL;
> +	}
> +
> +	num = ret;
> +	ctx->fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
> +						   GFP_KERNEL);
> +	if (!ctx->fan_cooling_levels)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u32_array(np, "cooling-levels",
> +					 ctx->fan_cooling_levels, num);
> +	if (ret) {
> +		dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
> +		return ret;
> +	}
> +
> +	for (i = 0; i < num; i++) {
> +		if (ctx->fan_cooling_levels[i] > MAX_SPEED) {
> +			dev_err(dev, "MCU fan state[%d]:%d > %d\n", i,
> +				ctx->fan_cooling_levels[i], MAX_SPEED);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	ctx->fan_max_level = num - 1;
> +	ctx->fan_register = KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG_V2;
> +
> +	return 0;
> +}
> +
>   static int khadas_mcu_fan_probe(struct platform_device *pdev)
>   {
>   	struct khadas_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
> @@ -90,6 +151,13 @@ static int khadas_mcu_fan_probe(struct platform_device *pdev)
>   	ctx->mcu = mcu;
>   	platform_set_drvdata(pdev, ctx);
>   
> +	ctx->fan_max_level = MAX_LEVEL;
> +	ctx->fan_register = KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG;
> +
> +	ret = khadas_mcu_fan_get_cooling_data_edge2(ctx, dev);
> +	if (ret)
> +		return ret;
> +
>   	cdev = devm_thermal_of_cooling_device_register(dev->parent,
>   			dev->parent->of_node, "khadas-mcu-fan", ctx,
>   			&khadas_mcu_fan_cooling_ops);