Re: [PATCHv2 2/6] pinctrl: sh-pfc: Add helper to handle bias lookup table

[Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>]

Hi Niklas,

Thank you for the patch.

On Friday 11 Nov 2016 21:30:17 Niklas Söderlund wrote:
> From: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> 
> On some SoC there are no simple mapping of pins to bias register bits
> and a lookup table is needed. This logic is already implemented in some
> SoC specific drivers that could benefit from a generic implementation.
> 
> Add helpers to deal with the lookup which later can be used by the SoC
> specific drivers. The logic used to lookup are different from the one it
> aims to replace, this is intentional. This new method reduces the memory
> consumption at the cost of increased CPU usage and fix a bug where a
> WARN() would incorrectly be triggered if the register offset is 0.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
>  drivers/pinctrl/sh-pfc/core.c   | 16 ++++++++++++++++
>  drivers/pinctrl/sh-pfc/core.h   |  4 ++++
>  drivers/pinctrl/sh-pfc/sh_pfc.h |  6 ++++++
>  3 files changed, 26 insertions(+)
> 
> diff --git a/drivers/pinctrl/sh-pfc/core.c b/drivers/pinctrl/sh-pfc/core.c
> index f3a8897..8e38df7 100644
> --- a/drivers/pinctrl/sh-pfc/core.c
> +++ b/drivers/pinctrl/sh-pfc/core.c
> @@ -389,6 +389,22 @@ int sh_pfc_config_mux(struct sh_pfc *pfc, unsigned
> mark, int pinmux_type) return 0;
>  }
> 
> +int sh_pfc_pin_to_bias_info(const struct sh_pfc_bias_info *pullups,
> +			    unsigned int num, unsigned int pin,
> +			    struct sh_pfc_bias_info *info)

How about returning a const struct sh_pfc_bias_info * instead ? This would 
avoid copying the data into the *info argument. You could then rename pullups 
to info (I don't really like the pullups name as the table can contain 
pulldown information as well).

> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < num; i++) {
> +		if (pullups[i].pin == pin) {
> +			*info = pullups[i];
> +			return 0;
> +		}
> +	}
> +
> +	return WARN_ON_ONCE(-EINVAL);
> +}
> +
>  static int sh_pfc_init_ranges(struct sh_pfc *pfc)
>  {
>  	struct sh_pfc_pin_range *range;
> diff --git a/drivers/pinctrl/sh-pfc/core.h b/drivers/pinctrl/sh-pfc/core.h
> index 0bbdea58..d902cd2 100644
> --- a/drivers/pinctrl/sh-pfc/core.h
> +++ b/drivers/pinctrl/sh-pfc/core.h
> @@ -33,4 +33,8 @@ void sh_pfc_write_reg(struct sh_pfc *pfc, u32 reg,
> unsigned int width, int sh_pfc_get_pin_index(struct sh_pfc *pfc, unsigned
> int pin);
>  int sh_pfc_config_mux(struct sh_pfc *pfc, unsigned mark, int pinmux_type);
> 
> +int sh_pfc_pin_to_bias_info(const struct sh_pfc_bias_info *pullups,
> +			    unsigned int num, unsigned int pin,
> +			    struct sh_pfc_bias_info *info);
> +
>  #endif /* __SH_PFC_CORE_H__ */
> diff --git a/drivers/pinctrl/sh-pfc/sh_pfc.h
> b/drivers/pinctrl/sh-pfc/sh_pfc.h index 2345421..fc82b6d 100644
> --- a/drivers/pinctrl/sh-pfc/sh_pfc.h
> +++ b/drivers/pinctrl/sh-pfc/sh_pfc.h
> @@ -189,6 +189,12 @@ struct sh_pfc_window {
>  	unsigned long size;
>  };
> 
> +struct sh_pfc_bias_info {
> +	unsigned int pin;

You should make this a u16, otherwise the structure will be padded to 8 bytes 
anyway, removing the benefit of storing reg and bit in 16 bits.

> +	u16 reg : 11;
> +	u16 bit : 5;
> +};
> +
>  struct sh_pfc_pin_range;
> 
>  struct sh_pfc {

-- 
Regards,

Laurent Pinchart
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