[PATCH v1] spi: designware: add support for bits-per-word DT binding

[Tom Rini]

On Fri, Feb 27, 2026 at 07:04:34PM +0800, Boon Khai Ng wrote:

> Add support for the bits-per-word device tree binding.
> 
> Signed-off-by: Boon Khai Ng <boon.khai.ng at altera.com>
> ---
>  drivers/spi/designware_spi.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
> index b520c727900..c41436a1dfb 100644
> --- a/drivers/spi/designware_spi.c
> +++ b/drivers/spi/designware_spi.c
> @@ -359,6 +359,7 @@ static int dw_spi_probe(struct udevice *bus)
>  	dw_spi_init_t init = (dw_spi_init_t)dev_get_driver_data(bus);
>  	struct dw_spi_plat *plat = dev_get_plat(bus);
>  	struct dw_spi_priv *priv = dev_get_priv(bus);
> +	u32 bits_per_word = 8;
>  	int ret;
>  	u32 version;
>  
> @@ -384,8 +385,19 @@ static int dw_spi_probe(struct udevice *bus)
>  		version >> 24, version >> 16, version >> 8, version,
>  		priv->max_xfer);
>  
> -	/* Currently only bits_per_word == 8 supported */
> -	priv->bits_per_word = 8;
> +	ret = ofnode_read_u32(dev_ofnode(bus), "bits-per-word", &bits_per_word);
> +	if (ret) {
> +		debug("%s no bits-per-word not found\n", __func__);
> +	} else {
> +		if (bits_per_word >= 4 && bits_per_word <= priv->max_xfer) {
> +			debug("%s %d bits-per-word found\n", __func__, bits_per_word);
> +		} else {
> +			printf("ignoring invalid bits-per-word %d\n", bits_per_word);
> +			bits_per_word = 8;
> +		}
> +	}
> +
> +	priv->bits_per_word = bits_per_word;
>  
>  	priv->tmode = 0; /* Tx & Rx */
>  

I don't see this binding in v7.0-rc1, did I miss it? Thanks.

-- 
Tom
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