[PATCH v2 1/4] spi: add per-driver bits-per-word mask

[Sascha Hauer]

On Mon, Apr 03, 2023 at 01:53:37PM +0200, Philipp Zabel wrote:
> Allow SPI hosts to signal per-transfer bits-per-word switching
> support and drivers to query it with spi_is_bpw_supported().
> 
> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> ---
>  include/spi/spi.h | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)

Applied, thanks

Sascha

> 
> diff --git a/include/spi/spi.h b/include/spi/spi.h
> index fa9329b08c80..809ebd8df1a8 100644
> --- a/include/spi/spi.h
> +++ b/include/spi/spi.h
> @@ -131,6 +131,11 @@ struct spi_message;
>   *	SPI slaves, and are numbered from zero to num_chipselects.
>   *	each slave has a chipselect signal, but it's common that not
>   *	every chipselect is connected to a slave.
> + * @bits_per_word_mask: A mask indicating which values of bits_per_word are
> + *	supported by the driver. Bit n indicates that a bits_per_word n+1 is
> + *	supported. If set, the SPI core will reject any transfer with an
> + *	unsupported bits_per_word. If not set, this value is simply ignored,
> + *	and it's up to the individual driver to perform any validation.
>   * @max_speed_hz: Highest supported transfer speed
>   * @setup: updates the device mode and clocking records used by a
>   *	device's SPI controller; protocol code may call this.  This
> @@ -165,6 +170,12 @@ struct spi_controller {
>  
>  	/* Optimized handlers for SPI memory-like operations */
>  	const struct spi_controller_mem_ops *mem_ops;
> +
> +	/* Bitmask of supported bits_per_word for transfers */
> +	u32			bits_per_word_mask;
> +#define SPI_BPW_MASK(bits) BIT((bits) - 1)
> +#define SPI_BPW_RANGE_MASK(min, max) GENMASK((max) - 1, (min) - 1)
> +
>  	/*
>  	 * on some hardware transfer size may be constrained
>  	 * the limit may depend on device transfer settings
> @@ -435,6 +446,26 @@ spi_transfer_del(struct spi_transfer *t)
>  	list_del(&t->transfer_list);
>  }
>  
> +/**
> + * spi_is_bpw_supported - Check if bits per word is supported
> + * @spi: SPI device
> + * @bpw: Bits per word
> + *
> + * This function checks to see if the SPI controller supports @bpw.
> + *
> + * Returns:
> + * True if @bpw is supported, false otherwise.
> + */
> +static inline bool spi_is_bpw_supported(struct spi_device *spi, u32 bpw)
> +{
> +	u32 bpw_mask = spi->master->bits_per_word_mask;
> +
> +	if (bpw == 8 || (bpw <= 32 && bpw_mask & SPI_BPW_MASK(bpw)))
> +		return true;
> +
> +	return false;
> +}
> +
>  /* All these synchronous SPI transfer routines are utilities layered
>   * over the core async transfer primitive.  Here, "synchronous" means
>   * they will sleep uninterruptibly until the async transfer completes.
> -- 
> 2.39.2
> 
> 
> 

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