[PATCH v2 0/2] spi: s3c64xx: add support exynos990-spi to new port config data

[PATCH v2 0/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Denzeel Oliva]

Exynos990 uses the same version of USI SPI (v2.1) as the GS101.
Removed fifo_lvl_mask and rx_lvl_offset, and changed to the new data
configuration port.

The difference from other new port configuration data is that fifo_depth
is only specified in fifo-depth in DT.

Exynos 990 data for SPI:
- The depth of the FIFO is not the same size on all nodes.
  A depth of 64 bytes is used on most nodes,
  while a depth of 256 bytes is used on 3 specific nodes (SPI 8/9/10).
- The Exynos 990 only allows access to 32-bit registers.
  If access is attempted with a different size, an error interrupt
  is generated. Therefore, it is necessary to perform write accesses to
  registers in 32-bit blocks.

Changes in v2:
- Added a default "fifo_depth = 64" to prevent crashes when "fifo-depth"
  is missing in the device tree (avoids divide-by-zero issues).
- No other functional changes.

Denzeel Oliva (2):
  spi: dt-bindings: samsung: add samsung,exynos990-spi compatible
  spi: s3c64xx: add support exynos990-spi to new port config data

 .../devicetree/bindings/spi/samsung,spi.yaml    |  1 +
 drivers/spi/spi-s3c64xx.c                       | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

-- 
2.48.1

[PATCH v2 1/2] spi: dt-bindings: samsung: add samsung,exynos990-spi compatible

[Denzeel Oliva]

Add "samsung,exynos990-spi" dedicated compatible for the SPI controller
on Exynos990 SoC. This ensures proper representation of the hardware
in the device tree.

Signed-off-by: Denzeel Oliva <wachiturroxd150@gmail.com>
---
 Documentation/devicetree/bindings/spi/samsung,spi.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/spi/samsung,spi.yaml b/Documentation/devicetree/bindings/spi/samsung,spi.yaml
index 3c206a64d..1d3c95bd2 100644
--- a/Documentation/devicetree/bindings/spi/samsung,spi.yaml
+++ b/Documentation/devicetree/bindings/spi/samsung,spi.yaml
@@ -24,6 +24,7 @@ properties:
           - samsung,exynos4210-spi
           - samsung,exynos5433-spi
           - samsung,exynos850-spi
+          - samsung,exynos990-spi
           - samsung,exynosautov9-spi
           - tesla,fsd-spi
       - items:
-- 
2.48.1

Re: [PATCH v2 1/2] spi: dt-bindings: samsung: add samsung,exynos990-spi compatible

[Sam Protsenko]

On Thu, Feb 13, 2025 at 2:41 PM Denzeel Oliva <wachiturroxd150@gmail.com> wrote:
>
> Add "samsung,exynos990-spi" dedicated compatible for the SPI controller
> on Exynos990 SoC. This ensures proper representation of the hardware
> in the device tree.
>
> Signed-off-by: Denzeel Oliva <wachiturroxd150@gmail.com>
> ---

Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>

>  Documentation/devicetree/bindings/spi/samsung,spi.yaml | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/Documentation/devicetree/bindings/spi/samsung,spi.yaml b/Documentation/devicetree/bindings/spi/samsung,spi.yaml
> index 3c206a64d..1d3c95bd2 100644
> --- a/Documentation/devicetree/bindings/spi/samsung,spi.yaml
> +++ b/Documentation/devicetree/bindings/spi/samsung,spi.yaml
> @@ -24,6 +24,7 @@ properties:
>            - samsung,exynos4210-spi
>            - samsung,exynos5433-spi
>            - samsung,exynos850-spi
> +          - samsung,exynos990-spi
>            - samsung,exynosautov9-spi
>            - tesla,fsd-spi
>        - items:
> --
> 2.48.1
>
>

[PATCH v2 2/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Denzeel Oliva]

Exynos990 uses the same version of USI SPI (v2.1) as the GS101.
Removed fifo_lvl_mask and rx_lvl_offset, and changed to the new data
configuration port.

The difference from other new port configuration data is that fifo_depth
is only specified in fifo-depth in DT.

Exynos 990 data for SPI:
- The depth of the FIFO is not the same size on all nodes.
  A depth of 64 bytes is used on most nodes,
  while a depth of 256 bytes is used on 3 specific nodes (SPI 8/9/10).
- The Exynos 990 only allows access to 32-bit registers.
  If access is attempted with a different size, an error interrupt
  is generated. Therefore, it is necessary to perform write accesses to
  registers in 32-bit blocks.
- To prevent potential issues when fifo-depth is not explicitly set in
  DT, a default value of 64 is assigned to ensure stable operation.

Signed-off-by: Denzeel Oliva <wachiturroxd150@gmail.com>
---
 drivers/spi/spi-s3c64xx.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 389275dbc..5f55763f9 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -1586,6 +1586,20 @@ static const struct s3c64xx_spi_port_config exynos850_spi_port_config = {
 	.quirks		= S3C64XX_SPI_QUIRK_CS_AUTO,
 };
 
+static const struct s3c64xx_spi_port_config exynos990_spi_port_config = {
+	/* If not specified in DT, defaults to 64 */
+	.fifo_depth     = 64,
+	.rx_fifomask    = S3C64XX_SPI_ST_RX_FIFO_RDY_V2,
+	.tx_fifomask    = S3C64XX_SPI_ST_TX_FIFO_RDY_V2,
+	.tx_st_done     = 25,
+	.clk_div        = 4,
+	.high_speed     = true,
+	.clk_from_cmu   = true,
+	.has_loopback   = true,
+	.use_32bit_io   = true,
+	.quirks         = S3C64XX_SPI_QUIRK_CS_AUTO,
+};
+
 static const struct s3c64xx_spi_port_config exynosautov9_spi_port_config = {
 	/* fifo_lvl_mask is deprecated. Use {rx, tx}_fifomask instead. */
 	.fifo_lvl_mask	= { 0x1ff, 0x1ff, 0x7f, 0x7f, 0x7f, 0x7f, 0x1ff, 0x7f,
@@ -1664,6 +1678,9 @@ static const struct of_device_id s3c64xx_spi_dt_match[] = {
 	{ .compatible = "samsung,exynos850-spi",
 			.data = &exynos850_spi_port_config,
 	},
+	{ .compatible = "samsung,exynos990-spi",
+			.data = &exynos990_spi_port_config,
+	},
 	{ .compatible = "samsung,exynosautov9-spi",
 			.data = &exynosautov9_spi_port_config,
 	},
-- 
2.48.1

Re: [PATCH v2 2/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Sam Protsenko]

On Thu, Feb 13, 2025 at 2:41 PM Denzeel Oliva <wachiturroxd150@gmail.com> wrote:
>
> Exynos990 uses the same version of USI SPI (v2.1) as the GS101.
> Removed fifo_lvl_mask and rx_lvl_offset, and changed to the new data
> configuration port.
>
> The difference from other new port configuration data is that fifo_depth
> is only specified in fifo-depth in DT.
>

In the code below I can see this bit:

    /* If not specified in DT, defaults to 64 */
    .fifo_depth     = 64,

Is that intentional or is it some leftover that was meant to be
removed before the submission? From s3c64xx_spi_probe() it looks like
the "fifo-depth" DT property is ignored if .fifo_depth is set in the
port_config:

    if (sdd->port_conf->fifo_depth)
        sdd->fifo_depth = sdd->port_conf->fifo_depth;
    else if (of_property_read_u32(pdev->dev.of_node, "fifo-depth",
&sdd->fifo_depth))
        sdd->fifo_depth = FIFO_DEPTH(sdd);

Btw, wouldn't it be reasonable to flip this probe() code the other way
around? So that the fact that the DT property is available is
prioritized, not its port_config counterpart. That would make it
possible to provide a sensible default in the port_config structure
and at the same time be able to override it by specifying the DT
property for nodes where it's needed. Just a thought, not strictly
related to this patch.

> Exynos 990 data for SPI:
> - The depth of the FIFO is not the same size on all nodes.
>   A depth of 64 bytes is used on most nodes,
>   while a depth of 256 bytes is used on 3 specific nodes (SPI 8/9/10).
> - The Exynos 990 only allows access to 32-bit registers.
>   If access is attempted with a different size, an error interrupt
>   is generated. Therefore, it is necessary to perform write accesses to
>   registers in 32-bit blocks.
> - To prevent potential issues when fifo-depth is not explicitly set in
>   DT, a default value of 64 is assigned to ensure stable operation.
>
> Signed-off-by: Denzeel Oliva <wachiturroxd150@gmail.com>
> ---
>  drivers/spi/spi-s3c64xx.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
> index 389275dbc..5f55763f9 100644
> --- a/drivers/spi/spi-s3c64xx.c
> +++ b/drivers/spi/spi-s3c64xx.c
> @@ -1586,6 +1586,20 @@ static const struct s3c64xx_spi_port_config exynos850_spi_port_config = {
>         .quirks         = S3C64XX_SPI_QUIRK_CS_AUTO,
>  };
>
> +static const struct s3c64xx_spi_port_config exynos990_spi_port_config = {
> +       /* If not specified in DT, defaults to 64 */
> +       .fifo_depth     = 64,

Talking about this line here.

> +       .rx_fifomask    = S3C64XX_SPI_ST_RX_FIFO_RDY_V2,
> +       .tx_fifomask    = S3C64XX_SPI_ST_TX_FIFO_RDY_V2,
> +       .tx_st_done     = 25,
> +       .clk_div        = 4,
> +       .high_speed     = true,
> +       .clk_from_cmu   = true,
> +       .has_loopback   = true,
> +       .use_32bit_io   = true,
> +       .quirks         = S3C64XX_SPI_QUIRK_CS_AUTO,
> +};
> +
>  static const struct s3c64xx_spi_port_config exynosautov9_spi_port_config = {
>         /* fifo_lvl_mask is deprecated. Use {rx, tx}_fifomask instead. */
>         .fifo_lvl_mask  = { 0x1ff, 0x1ff, 0x7f, 0x7f, 0x7f, 0x7f, 0x1ff, 0x7f,
> @@ -1664,6 +1678,9 @@ static const struct of_device_id s3c64xx_spi_dt_match[] = {
>         { .compatible = "samsung,exynos850-spi",
>                         .data = &exynos850_spi_port_config,
>         },
> +       { .compatible = "samsung,exynos990-spi",
> +                       .data = &exynos990_spi_port_config,
> +       },
>         { .compatible = "samsung,exynosautov9-spi",
>                         .data = &exynosautov9_spi_port_config,
>         },
> --
> 2.48.1
>
>

Re: [PATCH v2 2/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Tudor Ambarus]

Hi, Sam,

On 2/14/25 12:08 AM, Sam Protsenko wrote:
> On Thu, Feb 13, 2025 at 2:41 PM Denzeel Oliva <wachiturroxd150@gmail.com> wrote:
>>
>> Exynos990 uses the same version of USI SPI (v2.1) as the GS101.
>> Removed fifo_lvl_mask and rx_lvl_offset, and changed to the new data
>> configuration port.
>>
>> The difference from other new port configuration data is that fifo_depth
>> is only specified in fifo-depth in DT.
>>
> 
> In the code below I can see this bit:
> 
>     /* If not specified in DT, defaults to 64 */
>     .fifo_depth     = 64,
> 
> Is that intentional or is it some leftover that was meant to be
> removed before the submission? From s3c64xx_spi_probe() it looks like
> the "fifo-depth" DT property is ignored if .fifo_depth is set in the
> port_config:

fifo-depth in port config is intended for IPs where all their instances
use the same FIFO depth. fifo-depth from DT is ignored because the
compatible knows better than what developers may in DT in this case, it
is intentional.

> 
>     if (sdd->port_conf->fifo_depth)
>         sdd->fifo_depth = sdd->port_conf->fifo_depth;
>     else if (of_property_read_u32(pdev->dev.of_node, "fifo-depth",
> &sdd->fifo_depth))
>         sdd->fifo_depth = FIFO_DEPTH(sdd);
> 
> Btw, wouldn't it be reasonable to flip this probe() code the other way

No, please. IPs that have instances with different FIFO depths shall
rely only on DT to specify their FIFO depths.

Cheers,
ta

Re: [PATCH v2 2/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Sam Protsenko]

On Fri, Feb 14, 2025 at 12:39 AM Tudor Ambarus <tudor.ambarus@linaro.org> wrote:
>
> Hi, Sam,
>
> On 2/14/25 12:08 AM, Sam Protsenko wrote:
> > On Thu, Feb 13, 2025 at 2:41 PM Denzeel Oliva <wachiturroxd150@gmail.com> wrote:
> >>
> >> Exynos990 uses the same version of USI SPI (v2.1) as the GS101.
> >> Removed fifo_lvl_mask and rx_lvl_offset, and changed to the new data
> >> configuration port.
> >>
> >> The difference from other new port configuration data is that fifo_depth
> >> is only specified in fifo-depth in DT.
> >>
> >
> > In the code below I can see this bit:
> >
> >     /* If not specified in DT, defaults to 64 */
> >     .fifo_depth     = 64,
> >
> > Is that intentional or is it some leftover that was meant to be
> > removed before the submission? From s3c64xx_spi_probe() it looks like
> > the "fifo-depth" DT property is ignored if .fifo_depth is set in the
> > port_config:
>
> fifo-depth in port config is intended for IPs where all their instances
> use the same FIFO depth. fifo-depth from DT is ignored because the
> compatible knows better than what developers may in DT in this case, it
> is intentional.
>
> >
> >     if (sdd->port_conf->fifo_depth)
> >         sdd->fifo_depth = sdd->port_conf->fifo_depth;
> >     else if (of_property_read_u32(pdev->dev.of_node, "fifo-depth",
> > &sdd->fifo_depth))
> >         sdd->fifo_depth = FIFO_DEPTH(sdd);
> >
> > Btw, wouldn't it be reasonable to flip this probe() code the other way
>
> No, please. IPs that have instances with different FIFO depths shall
> rely only on DT to specify their FIFO depths.
>

Fair enough. Does it mean the port_config.fifo_depth should be made
obsolete? Or it makes sense for older SoCs where FIFO depth is fixed,
or something like that?

> Cheers,
> ta

Re: [PATCH v2 0/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Tudor Ambarus]

On 2/13/25 8:40 PM, Denzeel Oliva wrote:
> - Added a default "fifo_depth = 64" to prevent crashes when "fifo-depth"
>   is missing in the device tree (avoids divide-by-zero issues).

no, you shouldn't use fifo_depth as a fallback, it's misleading.
fifo_depth shall be used only if all your SPI instances use the same
FIFO size. If that's not the case, as in yours, you specify the FIFO
depth via DT.

You need to determine whether your IP works with 0 sized FIFOs and if
not, make the the DT fifo-depth mandatory and check that its value is > 0.

If the IP works with 0 sized FIFOs, you need to update the driver to
allow that and let the fifo-depth property optional in DT.