[PATCH v3 0/2] serial: 8250_dw: Add support for UltraRISC DP1000 uart

[PATCH v3 0/2] serial: 8250_dw: Add support for UltraRISC DP1000 uart

[Jia Wang]

This patch series adds support for the UltraRISC DP1000 UART controller.

The series includes two patches:
1. Document the DP1000-specific compatible string for this UART variant.
2. Update 8250_dw to use a fixed CPR value for the DP1000 UART.

The patches have been tested on Ultrarisc DP1000 development board with
Linux v7.0-rc7, verifying basic UART functionality.

Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
---
Changes in v3:
- Rebased on Linux v7.0-rc7.
- Patch 1:
   * Removed separate `items` entry for DP1000, merging it into the
     existing `enum` to comply with the schema.
   * Updated commit message to describe DP1000 UART hardware differences.
- Patch 2:
   * Drop the custom quirk for missing CPR register.
   * Switch to using DW_UART_QUIRK_CPR_VALUE to provide a fixed CPR value.
- Link to v2: https://patch.msgid.link/20260316-ultrarisc-serial-v2-0-6ab3e7fa891c@ultrarisc.com

Changes in v2:
- Rebased on Linux v7.0-rc4 (previously on v7.0-rc2).
- Reordered patch series: DT binding patch comes before driver changes.
- Updated commit message for DT binding patch.
- Link to v1: https://patch.msgid.link/20260316-ultrarisc-serial-v1-0-c464f3e933a5@ultrarisc.com

---
Jia Wang (2):
      dt-bindings: serial: snps-dw-apb-uart: Add UltraRISC DP1000 UART
      serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

 Documentation/devicetree/bindings/serial/snps-dw-apb-uart.yaml | 1 +
 drivers/tty/serial/8250/8250_dw.c                              | 7 +++++++
 2 files changed, 8 insertions(+)
---
base-commit: e774d5f1bc27a85f858bce7688509e866f8e8a4e
change-id: 20260309-ultrarisc-serial-64ff637edf26

Best regards,
--  
Jia Wang <wangjia@ultrarisc.com>

[PATCH v3 1/2] dt-bindings: serial: snps-dw-apb-uart: Add UltraRISC DP1000 UART

[Jia Wang]

UltraRISC DP1000 integrates a Synopsys DesignWare APB UART, but it does
not provide the standard CPR and UCV registers.

Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
---
 Documentation/devicetree/bindings/serial/snps-dw-apb-uart.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.yaml b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.yaml
index 6efe43089a74..f84600f66df8 100644
--- a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.yaml
+++ b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.yaml
@@ -77,6 +77,7 @@ properties:
               - starfive,jh7100-hsuart
               - starfive,jh7100-uart
               - starfive,jh7110-uart
+              - ultrarisc,dp1000-uart
           - const: snps,dw-apb-uart
       - const: snps,dw-apb-uart
 

-- 
2.34.1

[PATCH v3 2/2] serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

[Jia Wang]

The UltraRISC DP1000 UART does not provide the standard CPR register used
by 8250_dw to discover port capabilities.

Provide a fixed CPR value for the DP1000-specific compatible so the
driver can configure the port correctly.

Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
---
 drivers/tty/serial/8250/8250_dw.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 94beadb4024d..ca6dbdf75918 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -962,6 +962,12 @@ static const struct dw8250_platform_data dw8250_intc10ee = {
 	.quirks = DW_UART_QUIRK_IER_KICK,
 };
 
+static const struct dw8250_platform_data dw8250_ultrarisc_dp1000_data = {
+	.usr_reg = DW_UART_USR,
+	.cpr_value = 0x00022022,
+	.quirks = DW_UART_QUIRK_CPR_VALUE,
+};
+
 static const struct of_device_id dw8250_of_match[] = {
 	{ .compatible = "snps,dw-apb-uart", .data = &dw8250_dw_apb },
 	{ .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data },
@@ -969,6 +975,7 @@ static const struct of_device_id dw8250_of_match[] = {
 	{ .compatible = "renesas,rzn1-uart", .data = &dw8250_renesas_rzn1_data },
 	{ .compatible = "sophgo,sg2044-uart", .data = &dw8250_skip_set_rate_data },
 	{ .compatible = "starfive,jh7100-uart", .data = &dw8250_skip_set_rate_data },
+	{ .compatible = "ultrarisc,dp1000-uart", .data = &dw8250_ultrarisc_dp1000_data },
 	{ /* Sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, dw8250_of_match);

-- 
2.34.1

Re: [PATCH v3 2/2] serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

[Ilpo Järvinen]

On Tue, 21 Apr 2026, Jia Wang wrote:

> The UltraRISC DP1000 UART does not provide the standard CPR register used
> by 8250_dw to discover port capabilities.
> 
> Provide a fixed CPR value for the DP1000-specific compatible so the
> driver can configure the port correctly.
> 
> Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
> ---
>  drivers/tty/serial/8250/8250_dw.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index 94beadb4024d..ca6dbdf75918 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -962,6 +962,12 @@ static const struct dw8250_platform_data dw8250_intc10ee = {
>  	.quirks = DW_UART_QUIRK_IER_KICK,
>  };
>  
> +static const struct dw8250_platform_data dw8250_ultrarisc_dp1000_data = {
> +	.usr_reg = DW_UART_USR,
> +	.cpr_value = 0x00022022,

Hi,

Please construct the cpr_value by ORing DW_UART_CPR_* defines together.
For fields, FIELD_PREP_CONST() may be useful.

In order to be able to use the DW_UART_CPR_* defines, they need to be 
moved into 8250_dwlib.h (I'd move all DW_UART register defines in a 
preparatory patch).

I know the existing Renesas' .cpr_value doesn't follow this convention but 
that could be converted as well (in another patch, or leave the Renesas 
entry conversion to me if you don't want to do that).

> +	.quirks = DW_UART_QUIRK_CPR_VALUE,
> +};
> +
>  static const struct of_device_id dw8250_of_match[] = {
>  	{ .compatible = "snps,dw-apb-uart", .data = &dw8250_dw_apb },
>  	{ .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data },
> @@ -969,6 +975,7 @@ static const struct of_device_id dw8250_of_match[] = {
>  	{ .compatible = "renesas,rzn1-uart", .data = &dw8250_renesas_rzn1_data },
>  	{ .compatible = "sophgo,sg2044-uart", .data = &dw8250_skip_set_rate_data },
>  	{ .compatible = "starfive,jh7100-uart", .data = &dw8250_skip_set_rate_data },
> +	{ .compatible = "ultrarisc,dp1000-uart", .data = &dw8250_ultrarisc_dp1000_data },
>  	{ /* Sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, dw8250_of_match);
> 
> 

-- 
 i.

Re: [PATCH v3 1/2] dt-bindings: serial: snps-dw-apb-uart: Add UltraRISC DP1000 UART

[Conor Dooley]

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On Tue, Apr 21, 2026 at 01:58:51PM +0800, Jia Wang wrote:
> UltraRISC DP1000 integrates a Synopsys DesignWare APB UART, but it does
> not provide the standard CPR and UCV registers.
> 
> Signed-off-by: Jia Wang <wangjia@ultrarisc.com>

Acked-by: Conor Dooley <conor.dooley@microchip.com>

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Re: [PATCH v3 2/2] serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

[Jia Wang]

On 2026-04-21 15:18 +0300, Ilpo Järvinen wrote:
> On Tue, 21 Apr 2026, Jia Wang wrote:
> 
> > The UltraRISC DP1000 UART does not provide the standard CPR register used
> > by 8250_dw to discover port capabilities.
> > 
> > Provide a fixed CPR value for the DP1000-specific compatible so the
> > driver can configure the port correctly.
> > 
> > Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
> > ---
> >  drivers/tty/serial/8250/8250_dw.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> > index 94beadb4024d..ca6dbdf75918 100644
> > --- a/drivers/tty/serial/8250/8250_dw.c
> > +++ b/drivers/tty/serial/8250/8250_dw.c
> > @@ -962,6 +962,12 @@ static const struct dw8250_platform_data dw8250_intc10ee = {
> >  	.quirks = DW_UART_QUIRK_IER_KICK,
> >  };
> >  
> > +static const struct dw8250_platform_data dw8250_ultrarisc_dp1000_data = {
> > +	.usr_reg = DW_UART_USR,
> > +	.cpr_value = 0x00022022,
> 
> Hi,
> 
> Please construct the cpr_value by ORing DW_UART_CPR_* defines together.
> For fields, FIELD_PREP_CONST() may be useful.
> 
> In order to be able to use the DW_UART_CPR_* defines, they need to be 
> moved into 8250_dwlib.h (I'd move all DW_UART register defines in a 
> preparatory patch).
> 
> I know the existing Renesas' .cpr_value doesn't follow this convention but 
> that could be converted as well (in another patch, or leave the Renesas 
> entry conversion to me if you don't want to do that).
>

Thanks for the review.

Just to confirm: since you mentioned that the preparatory patch moving
the DW_UART register defines is already in place, I don't need to move
them again, correct?

I will update my patch to use the DW_UART_CPR_* macros and
FIELD_PREP_CONST() accordingly, and I’m happy to add a separate patch in
the next revision to convert the Renesas .cpr_value as well.
 
> > +	.quirks = DW_UART_QUIRK_CPR_VALUE,
> > +};
> > +
> >  static const struct of_device_id dw8250_of_match[] = {
> >  	{ .compatible = "snps,dw-apb-uart", .data = &dw8250_dw_apb },
> >  	{ .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data },
> > @@ -969,6 +975,7 @@ static const struct of_device_id dw8250_of_match[] = {
> >  	{ .compatible = "renesas,rzn1-uart", .data = &dw8250_renesas_rzn1_data },
> >  	{ .compatible = "sophgo,sg2044-uart", .data = &dw8250_skip_set_rate_data },
> >  	{ .compatible = "starfive,jh7100-uart", .data = &dw8250_skip_set_rate_data },
> > +	{ .compatible = "ultrarisc,dp1000-uart", .data = &dw8250_ultrarisc_dp1000_data },
> >  	{ /* Sentinel */ }
> >  };
> >  MODULE_DEVICE_TABLE(of, dw8250_of_match);
> > 
> > 
> 
> -- 
>  i.
> 
> 

Regards,
Jia

Re: [PATCH v3 2/2] serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

[Andy Shevchenko]

On Wed, Apr 22, 2026 at 08:57:56AM +0800, Jia Wang wrote:
> On 2026-04-21 15:18 +0300, Ilpo Järvinen wrote:
> > On Tue, 21 Apr 2026, Jia Wang wrote:

...

> > > +static const struct dw8250_platform_data dw8250_ultrarisc_dp1000_data = {
> > > +	.usr_reg = DW_UART_USR,
> > > +	.cpr_value = 0x00022022,
> > 
> > Please construct the cpr_value by ORing DW_UART_CPR_* defines together.
> > For fields, FIELD_PREP_CONST() may be useful.
> > 
> > In order to be able to use the DW_UART_CPR_* defines, they need to be 
> > moved into 8250_dwlib.h (I'd move all DW_UART register defines in a 
> > preparatory patch).
> > 
> > I know the existing Renesas' .cpr_value doesn't follow this convention but 
> > that could be converted as well (in another patch, or leave the Renesas 
> > entry conversion to me if you don't want to do that).
> 
> Thanks for the review.
> 
> Just to confirm: since you mentioned that the preparatory patch moving
> the DW_UART register defines is already in place, I don't need to move
> them again, correct?
> 
> I will update my patch to use the DW_UART_CPR_* macros and
> FIELD_PREP_CONST() accordingly, and I’m happy to add a separate patch in
> the next revision to convert the Renesas .cpr_value as well.

My understanding that you want to send a patch series of 3 patches:
- moving DW_UART_CPR_* values from C-file to h-file
- modify existing Renesas case
- add support for your HW (this patch in updated form)

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/2] serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

[Andy Shevchenko]

On Wed, Apr 22, 2026 at 11:45:44AM +0300, Andy Shevchenko wrote:
> On Wed, Apr 22, 2026 at 08:57:56AM +0800, Jia Wang wrote:

...

> > Just to confirm: since you mentioned that the preparatory patch moving
> > the DW_UART register defines is already in place, I don't need to move
> > them again, correct?
> > 
> > I will update my patch to use the DW_UART_CPR_* macros and
> > FIELD_PREP_CONST() accordingly, and I’m happy to add a separate patch in
> > the next revision to convert the Renesas .cpr_value as well.
> 
> My understanding that you want to send a patch series of 3 patches:
> - moving DW_UART_CPR_* values from C-file to h-file
> - modify existing Renesas case

- DT binding for new HW (patch 1 of this series)

> - add support for your HW (this patch in updated form)

And I forgot that you have a DT binging one... So 4 patches after all.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/2] serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

[Ilpo Järvinen]

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On Wed, 22 Apr 2026, Jia Wang wrote:

> On 2026-04-21 15:18 +0300, Ilpo Järvinen wrote:
> > On Tue, 21 Apr 2026, Jia Wang wrote:
> > 
> > > The UltraRISC DP1000 UART does not provide the standard CPR register used
> > > by 8250_dw to discover port capabilities.
> > > 
> > > Provide a fixed CPR value for the DP1000-specific compatible so the
> > > driver can configure the port correctly.
> > > 
> > > Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
> > > ---
> > >  drivers/tty/serial/8250/8250_dw.c | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > > 
> > > diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> > > index 94beadb4024d..ca6dbdf75918 100644
> > > --- a/drivers/tty/serial/8250/8250_dw.c
> > > +++ b/drivers/tty/serial/8250/8250_dw.c
> > > @@ -962,6 +962,12 @@ static const struct dw8250_platform_data dw8250_intc10ee = {
> > >  	.quirks = DW_UART_QUIRK_IER_KICK,
> > >  };
> > >  
> > > +static const struct dw8250_platform_data dw8250_ultrarisc_dp1000_data = {
> > > +	.usr_reg = DW_UART_USR,
> > > +	.cpr_value = 0x00022022,
> > 
> > Hi,
> > 
> > Please construct the cpr_value by ORing DW_UART_CPR_* defines together.
> > For fields, FIELD_PREP_CONST() may be useful.
> > 
> > In order to be able to use the DW_UART_CPR_* defines, they need to be 
> > moved into 8250_dwlib.h (I'd move all DW_UART register defines in a 
> > preparatory patch).
> > 
> > I know the existing Renesas' .cpr_value doesn't follow this convention but 
> > that could be converted as well (in another patch, or leave the Renesas 
> > entry conversion to me if you don't want to do that).
> >
> 
> Thanks for the review.
> 
> Just to confirm: since you mentioned that the preparatory patch moving
> the DW_UART register defines is already in place, I don't need to move
> them again, correct?

I'm not sure where that preparatory patch is. Those defines still appear 
in 8250_dwlib.c AFAICT.

To be clear, DW_UART_CPR_* defines are in 8250_dwlib.c but you're 
modifying 8250_dw.c file here so you cannot use those pre-existing defines 
as is in 8250_dw.c. To solve that, please add a preparatory patch into 
your series which relocates all those defines from 8250_dwlib.c to 
8250_dwlib.h. If there's a patch which does that already, it has missed my 
radar.

And my suggestion is to move not just DW_UART_CPR_* defines into 
8250_dwlib.h but all DW UART specific register defines to keep them in 
the same place.

Hopefully this clears up any misunderstanding.


My main point all along is that do not do the define move in the same 
patch where you're adding UltraRISC DP1000 UART (which is a common pitfall 
to many submitters so I try to give pro-active instructions while 
reviewing to avoid extra versions because of them).

> I will update my patch to use the DW_UART_CPR_* macros and
> FIELD_PREP_CONST() accordingly, and I’m happy to add a separate patch in
> the next revision to convert the Renesas .cpr_value as well.

Great, thanks.

> > > +	.quirks = DW_UART_QUIRK_CPR_VALUE,
> > > +};

-- 
 i.