[PACTH v2] spi: imx: add 16/32 bits per word support for target mode

[Carlos Song]

> -----Original Message-----
> From: Frank Li <frank.li at nxp.com>
> Sent: Friday, October 24, 2025 9:25 PM
> To: Carlos Song <carlos.song at nxp.com>
> Cc: mkl at pengutronix.de; broonie at kernel.org; shawnguo at kernel.org;
> s.hauer at pengutronix.de; kernel at pengutronix.de; festevam at gmail.com;
> linux-spi at vger.kernel.org; imx at lists.linux.dev;
> linux-arm-kernel at lists.infradead.org; linux-kernel at vger.kernel.org
> Subject: Re: [PACTH v2] spi: imx: add 16/32 bits per word support for target
> mode
> 
> On Fri, Oct 24, 2025 at 07:31:07PM +0800, carlos.song at nxp.com wrote:
> > From: Carlos Song <carlos.song at nxp.com>
> >
> > Now for ECSPI only support 8 bits per word in target mode.
> > Enable 16/32 bits per word support for spi-imx target mode.
> >
> > Signed-off-by: Carlos Song <carlos.song at nxp.com>
> > Signed-off-by: Clark Wang <xiaoning.wang at nxp.com>
> > ---
> >  drivers/spi/spi-imx.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index
> > 155ddeb8fcd4..017f83f5dfdf 100644
> > --- a/drivers/spi/spi-imx.c
> > +++ b/drivers/spi/spi-imx.c
> > @@ -424,8 +424,12 @@ static void spi_imx_buf_tx_swap(struct
> > spi_imx_data *spi_imx)
> >
> >  static void mx53_ecspi_rx_target(struct spi_imx_data *spi_imx)  {
> > -	u32 val = ioread32be(spi_imx->base + MXC_CSPIRXDATA);
> > +	u32 val = readl(spi_imx->base + MXC_CSPIRXDATA);
> >
> > +	if (spi_imx->bits_per_word <= 8)
> > +		swab32s(&val);
> > +	else if (spi_imx->bits_per_word <= 16)
> > +		swahw32s(&val);
> 
> Needn't swap when bits_per_word > 24, like 32? or our hardware max support
> to 16?
> 
> Frank

I think we don't need. We are reading/writing FIFO by 32-bits word. In this case, we just need keep
the default byte order.

Is it more reasonable only support bits per word=8/16/32 for target mode?
-b 8/16/32 can cover most use case.

Carlos
> >  	if (spi_imx->rx_buf) {
> >  		int n_bytes = spi_imx->target_burst % sizeof(val);
> >
> > @@ -453,12 +457,16 @@ static void mx53_ecspi_tx_target(struct
> spi_imx_data *spi_imx)
> >  	if (spi_imx->tx_buf) {
> >  		memcpy(((u8 *)&val) + sizeof(val) - n_bytes,
> >  		       spi_imx->tx_buf, n_bytes);
> > +		if (spi_imx->bits_per_word <= 8)
> > +			swab32s(&val);
> > +		else if (spi_imx->bits_per_word <= 16)
> > +			swahw32s(&val);
> >  		spi_imx->tx_buf += n_bytes;
> >  	}
> >
> >  	spi_imx->count -= n_bytes;
> >
> > -	iowrite32be(val, spi_imx->base + MXC_CSPITXDATA);
> > +	writel(val, spi_imx->base + MXC_CSPITXDATA);
> >  }
> >
> >  /* MX51 eCSPI */
> > --
> > 2.34.1
> >