[PATCH v1 0/2] spi: s3c64xx: add support for samsung,exynos990-spi

[PATCH v1 0/2] spi: s3c64xx: add support for samsung,exynos990-spi

[Denzeel Oliva]

The Exynos990 SPI controller shares similarities with
the GS101 (Google Tensor) SPI implementation,
but introduces specific hardware requirements such as
32-bit register access and variable FIFO depths depending on
the SPI node where it will have to be specified in DT (Device Tree).

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 v1 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

[PATCH v1 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.

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..790034d2d 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 = {
+	/* fifo-depth must be specified in the device tree. */
+	.fifo_depth	= 0,
+	.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 v1 2/2] spi: s3c64xx: add support exynos990-spi to new port config data

[Tudor Ambarus]

On 2/12/25 7:12 PM, Denzeel Oliva wrote:
> +static const struct s3c64xx_spi_port_config exynos990_spi_port_config = {
> +	/* fifo-depth must be specified in the device tree. */
> +	.fifo_depth	= 0,

have you tried testing without specifying the fifo_depth in DT?

You'll probably hit a divide by zero at:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/spi/spi-s3c64xx.c#n664

I assume the controller can work with 0 sized FIFO depth, and if so, the
driver has to be updated to allow 0 sized FIFOs.

btw, how did you test the set?

Re: [PATCH v1 0/2] spi: s3c64xx: add support for samsung,exynos990-spi

[Tudor Ambarus]

Hi!

On 2/12/25 7:12 PM, Denzeel Oliva wrote:
> The Exynos990 SPI controller shares similarities with
> the GS101 (Google Tensor) SPI implementation,
> but introduces specific hardware requirements such as
> 32-bit register access and variable FIFO depths depending on

gs101 mandates 32-bit accesses too.

> the SPI node where it will have to be specified in DT (Device Tree).

gs101 has some USI nodes that can work only in uart mode and indeed the
fifosize there is 256. Does downstream define SPI nodes with 256 bytes
FIFOs? Can you please point me the the downstream code?

Cheers,
ta

> 
> 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(+)
> 

Re: [PATCH v1 0/2] spi: s3c64xx: add support for samsung,exynos990-spi

[Denzeel Oliva]

On Thu, Feb 13, 2025 at 07:05:22AM +0000, Tudor Ambarus wrote:
> gs101 mandates 32-bit accesses too.

Also in exynos990 [0]

> > the SPI node where it will have to be specified in DT (Device Tree).
> 
> gs101 has some USI nodes that can work only in uart mode and indeed the
> fifosize there is 256. Does downstream define SPI nodes with 256 bytes
> FIFOs? Can you please point me the the downstream code?
> 

Yes, Exynos990 has SPI nodes with 256-byte FIFOs, and you can see this in
the downstream kernel. Here are some relevant references:

- SPI8: [1]
- SPI9: [2]
- SPI10: [3]

Best regards,
Denzeel

[0] https://github.com/pascua28/android_kernel_samsung_s20fe/blob/3be539e9cd22b89ba3cc8282945a0c46ff27341d/drivers/spi/spi-s3c64xx.c#L767
[1] https://github.com/pascua28/android_kernel_samsung_s20fe/blob/3be539e9cd22b89ba3cc8282945a0c46ff27341d/arch/arm64/boot/dts/exynos/exynos9830-usi.dtsi#L1641
[2] https://github.com/pascua28/android_kernel_samsung_s20fe/blob/3be539e9cd22b89ba3cc8282945a0c46ff27341d/arch/arm64/boot/dts/exynos/exynos9830-usi.dtsi#L1662
[3] https://github.com/pascua28/android_kernel_samsung_s20fe/blob/3be539e9cd22b89ba3cc8282945a0c46ff27341d/arch/arm64/boot/dts/exynos/exynos9830-usi.dtsi#L1683

Re: [PATCH v1 0/2] spi: s3c64xx: add support for samsung,exynos990-spi

[Tudor Ambarus]

On 2/13/25 7:47 PM, Denzeel Oliva wrote:
> Yes, Exynos990 has SPI nodes with 256-byte FIFOs, and you can see this in
> the downstream kernel. Here are some relevant references:

thanks for the references!