Re: [PATCH 2/5] reset: imx8mp-audiomix: Prepare the code for more reset bits

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Daniel,

On Di, 2025-02-18 at 10:57 +0200, Daniel Baluta wrote:
> Current code supports EARC PHY Software Reset and EARC 	Software
> Reset but it is not easily extensible to more reset bits.
> 
> So, refactor the code in order to easily allow more reset bits
> in the future.
> 
> Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
> ---
>  drivers/reset/reset-imx8mp-audiomix.c | 53 ++++++++++++++++++++++-----
>  1 file changed, 43 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/reset/reset-imx8mp-audiomix.c b/drivers/reset/reset-imx8mp-audiomix.c
> index 1fe21980a66c..6b1666c4e069 100644
> --- a/drivers/reset/reset-imx8mp-audiomix.c
> +++ b/drivers/reset/reset-imx8mp-audiomix.c
> @@ -12,7 +12,30 @@
>  #include <linux/reset-controller.h>
>  
>  #define IMX8MP_AUDIOMIX_EARC_OFFSET		0x200
> -#define IMX8MP_AUDIOMIX_EARC_RESET_MASK		0x3
> +#define IMX8MP_AUDIOMIX_EARC_RESET_MASK		0x1
> +#define IMX8MP_AUDIOMIX_EARC_PHY_RESET_MASK	0x2

Will any of the reset controls manipulate multiple bits at once?
I'd use BIT(0) and BIT(1) here.

> +
> +#define IMX8MP_AUDIOMIX_EARC		0
> +#define IMX8MP_AUDIOMIX_EARC_PHY	1
> +
> +#define IMX8MP_AUDIOMIX_RESET_NUM	2
> +
> +struct imx8mp_reset_map {
> +	unsigned int offset;
> +	unsigned int mask;
> +};
> +
> +static const struct imx8mp_reset_map reset_map[IMX8MP_AUDIOMIX_RESET_NUM] = {

If you make this reset_map[], drop IMX8MP_AUDIOMIX_RESET_NUM, and use
.nr_resets = ARRAY_SIZE(reset_map) below, followup patches that add new
bits will be simplified.

> +	[IMX8MP_AUDIOMIX_EARC] = {
> +		.offset	= IMX8MP_AUDIOMIX_EARC_OFFSET,
> +		.mask	= IMX8MP_AUDIOMIX_EARC_RESET_MASK,
> +	},
> +	[IMX8MP_AUDIOMIX_EARC_PHY] = {
> +		.offset	= IMX8MP_AUDIOMIX_EARC_OFFSET,
> +		.mask	= IMX8MP_AUDIOMIX_EARC_PHY_RESET_MASK,
> +	},
> +

Please drop this empty line.

> +};
>  
>  struct imx8mp_audiomix_reset {
>  	struct reset_controller_dev rcdev;
> @@ -30,13 +53,18 @@ static int imx8mp_audiomix_reset_assert(struct reset_controller_dev *rcdev,
>  {
>  	struct imx8mp_audiomix_reset *priv = to_imx8mp_audiomix_reset(rcdev);
>  	void __iomem *reg_addr = priv->base;
> -	unsigned int mask, reg;
> +	unsigned int mask, offset, reg;
>  	unsigned long flags;
>  
> -	mask = BIT(id);
> +	if (id >=  IMX8MP_AUDIOMIX_RESET_NUM)

Whitespace error. But also, this check is not necessary.
The reset core will not return reset controls that fail the same check
in of_reset_simple_xlate(), so we can never get here with the wrong id
if rcdev.nr_resets correctly is set to ARRAY_SIZE(reset_map).

> +		return -EINVAL;
> +
> +	mask = reset_map[id].mask;
> +	offset = reset_map[id].offset;
> +
>  	spin_lock_irqsave(&priv->lock, flags);
> -	reg = readl(reg_addr + IMX8MP_AUDIOMIX_EARC_OFFSET);
> -	writel(reg & ~mask, reg_addr + IMX8MP_AUDIOMIX_EARC_OFFSET);
> +	reg = readl(reg_addr + offset);
> +	writel(reg & ~mask, reg_addr + offset);
>  	spin_unlock_irqrestore(&priv->lock, flags);
>  
>  	return 0;
> @@ -47,13 +75,18 @@ static int imx8mp_audiomix_reset_deassert(struct reset_controller_dev *rcdev,
>  {
>  	struct imx8mp_audiomix_reset *priv = to_imx8mp_audiomix_reset(rcdev);
>  	void __iomem *reg_addr = priv->base;
> -	unsigned int mask, reg;
> +	unsigned int mask, offset, reg;
>  	unsigned long flags;
>  
> -	mask = BIT(id);
> +	if (id >=  IMX8MP_AUDIOMIX_RESET_NUM)
> +		return -EINVAL;

Same as above.

> +
> +	mask = reset_map[id].mask;
> +	offset = reset_map[id].offset;
> +
>  	spin_lock_irqsave(&priv->lock, flags);
> -	reg = readl(reg_addr + IMX8MP_AUDIOMIX_EARC_OFFSET);
> -	writel(reg | mask, reg_addr + IMX8MP_AUDIOMIX_EARC_OFFSET);
> +	reg = readl(reg_addr + offset);
> +	writel(reg | mask, reg_addr + offset);
>  	spin_unlock_irqrestore(&priv->lock, flags);
>  
>  	return 0;
> @@ -78,7 +111,7 @@ static int imx8mp_audiomix_reset_probe(struct auxiliary_device *adev,
>  	spin_lock_init(&priv->lock);
>  
>  	priv->rcdev.owner     = THIS_MODULE;
> -	priv->rcdev.nr_resets = fls(IMX8MP_AUDIOMIX_EARC_RESET_MASK);
> +	priv->rcdev.nr_resets = IMX8MP_AUDIOMIX_RESET_NUM;

Could use ARRAY_SIZE(reset_map) here.

regards
Philipp