[v1] Add support for enhanced SPI for Designware SPI controllers

[PATCH 04/11] spi: dw: use TMOD_RO to read in enhanced spi modes

Posted by Sudip Mukherjee 3 years, 8 months ago

When we are using the enhanced spi modes we can not use EEPROM Read.
The Synopsys datasheet mentions EEPROM Read is not applicable in
enhanced SPI modes. We will need to use Receive only mode.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
---
 drivers/spi/spi-dw-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index 8c84a2e991b5..8e624620864f 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -727,7 +727,10 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	cfg.dfs = 8;
 	cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
 	if (op->data.dir == SPI_MEM_DATA_IN) {
-		cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
+		if (enhanced_spi)
+			cfg.tmode = DW_SPI_CTRLR0_TMOD_RO;
+		else
+			cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
 		cfg.ndf = op->data.nbytes;
 	} else {
 		cfg.tmode = DW_SPI_CTRLR0_TMOD_TO;
-- 
2.30.2

Re: [PATCH 04/11] spi: dw: use TMOD_RO to read in enhanced spi modes

Posted by Serge Semin 3 years, 7 months ago

On Tue, Aug 02, 2022 at 06:57:48PM +0100, Sudip Mukherjee wrote:
> When we are using the enhanced spi modes we can not use EEPROM Read.
> The Synopsys datasheet mentions EEPROM Read is not applicable in
> enhanced SPI modes. We will need to use Receive only mode.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
> ---
>  drivers/spi/spi-dw-core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index 8c84a2e991b5..8e624620864f 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -727,7 +727,10 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
>  	cfg.dfs = 8;
>  	cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
>  	if (op->data.dir == SPI_MEM_DATA_IN) {
> -		cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;

> +		if (enhanced_spi)
> +			cfg.tmode = DW_SPI_CTRLR0_TMOD_RO;
> +		else
> +			cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;

Just drop this modification and initialize the dw_spi_cfg structure
from scratch in the Enhanced SPI-specific method:
dw_spi_exec_enh_mem_op().

-Sergey

>  		cfg.ndf = op->data.nbytes;
>  	} else {
>  		cfg.tmode = DW_SPI_CTRLR0_TMOD_TO;
> -- 
> 2.30.2
>

Re: [PATCH 04/11] spi: dw: use TMOD_RO to read in enhanced spi modes

Posted by Mark Brown 3 years, 8 months ago

On Tue, Aug 02, 2022 at 06:57:48PM +0100, Sudip Mukherjee wrote:
> When we are using the enhanced spi modes we can not use EEPROM Read.
> The Synopsys datasheet mentions EEPROM Read is not applicable in
> enhanced SPI modes. We will need to use Receive only mode.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
> ---
>  drivers/spi/spi-dw-core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index 8c84a2e991b5..8e624620864f 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -727,7 +727,10 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
>  	cfg.dfs = 8;
>  	cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
>  	if (op->data.dir == SPI_MEM_DATA_IN) {
> -		cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
> +		if (enhanced_spi)
> +			cfg.tmode = DW_SPI_CTRLR0_TMOD_RO;
> +		else
> +			cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;

This is fixing the previous commit...

Re: [PATCH 04/11] spi: dw: use TMOD_RO to read in enhanced spi modes

Posted by Sudip Mukherjee 3 years, 8 months ago

Hi Mark,

On Tue, Aug 2, 2022 at 8:13 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Tue, Aug 02, 2022 at 06:57:48PM +0100, Sudip Mukherjee wrote:
> > When we are using the enhanced spi modes we can not use EEPROM Read.
> > The Synopsys datasheet mentions EEPROM Read is not applicable in
> > enhanced SPI modes. We will need to use Receive only mode.
> >
> > Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
> > ---
> >  drivers/spi/spi-dw-core.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> > index 8c84a2e991b5..8e624620864f 100644
> > --- a/drivers/spi/spi-dw-core.c
> > +++ b/drivers/spi/spi-dw-core.c
> > @@ -727,7 +727,10 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
> >       cfg.dfs = 8;
> >       cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
> >       if (op->data.dir == SPI_MEM_DATA_IN) {
> > -             cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
> > +             if (enhanced_spi)
> > +                     cfg.tmode = DW_SPI_CTRLR0_TMOD_RO;
> > +             else
> > +                     cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
>
> This is fixing the previous commit...

This was not actually meant to be a fixup patch. I intentionally made
it separate so that "enhanced_spi" is introduced in the previous
patch,
and then modified the tmode read protocol in this patch based on
enhanced_spi. But I can merge it with the previous patch like you have
suggested.

--
Regards
Sudip