[PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Nick Hu]

Add compatible string and property for the SiFive CLINT v2. The SiFive
CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
in their control methods.

Signed-off-by: Nick Hu <nick.hu@sifive.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
---
- v3 changes:
  - Add the reason for the incompatibility between sifive,clint2 and
    sifive,clint0.
- v2 changes:
  - Don't allow sifive,clint2 by itself. Add '-{}' to the first entry
  - Mark the sifive,fine-ctr-bits as the required property when
    the compatible includes the sifive,clint2

 .../bindings/timer/sifive,clint.yaml          | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
index 76d83aea4e2b..34684cda8b15 100644
--- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
+++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
@@ -36,6 +36,12 @@ properties:
               - starfive,jh7110-clint   # StarFive JH7110
               - starfive,jh8100-clint   # StarFive JH8100
           - const: sifive,clint0        # SiFive CLINT v0 IP block
+      - items:
+          - {}
+          - const: sifive,clint2        # SiFive CLINT v2 IP block
+        description:
+          SiFive CLINT v2 is the HRT that supports the Zicntr. The control of sifive,clint2
+          differs from that of sifive,clint0, making them incompatible.
       - items:
           - enum:
               - allwinner,sun20i-d1-clint
@@ -62,6 +68,22 @@ properties:
     minItems: 1
     maxItems: 4095
 
+  sifive,fine-ctr-bits:
+    maximum: 15
+    description: The width in bits of the fine counter.
+
+if:
+  properties:
+    compatible:
+      contains:
+        const: sifive,clint2
+then:
+  required:
+    - sifive,fine-ctr-bits
+else:
+  properties:
+    sifive,fine-ctr-bits: false
+
 additionalProperties: false
 
 required:
-- 
2.17.1

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 2269 bytes --]

On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> Add compatible string and property for the SiFive CLINT v2. The SiFive
> CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> in their control methods.
> 
> Signed-off-by: Nick Hu <nick.hu@sifive.com>
> Reviewed-by: Samuel Holland <samuel.holland@sifive.com>

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

> ---
> - v3 changes:
>   - Add the reason for the incompatibility between sifive,clint2 and
>     sifive,clint0.
> - v2 changes:
>   - Don't allow sifive,clint2 by itself. Add '-{}' to the first entry
>   - Mark the sifive,fine-ctr-bits as the required property when
>     the compatible includes the sifive,clint2
> 
>  .../bindings/timer/sifive,clint.yaml          | 22 +++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> index 76d83aea4e2b..34684cda8b15 100644
> --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> @@ -36,6 +36,12 @@ properties:
>                - starfive,jh7110-clint   # StarFive JH7110
>                - starfive,jh8100-clint   # StarFive JH8100
>            - const: sifive,clint0        # SiFive CLINT v0 IP block
> +      - items:
> +          - {}
> +          - const: sifive,clint2        # SiFive CLINT v2 IP block
> +        description:
> +          SiFive CLINT v2 is the HRT that supports the Zicntr. The control of sifive,clint2
> +          differs from that of sifive,clint0, making them incompatible.
>        - items:
>            - enum:
>                - allwinner,sun20i-d1-clint
> @@ -62,6 +68,22 @@ properties:
>      minItems: 1
>      maxItems: 4095
>  
> +  sifive,fine-ctr-bits:
> +    maximum: 15
> +    description: The width in bits of the fine counter.
> +
> +if:
> +  properties:
> +    compatible:
> +      contains:
> +        const: sifive,clint2
> +then:
> +  required:
> +    - sifive,fine-ctr-bits
> +else:
> +  properties:
> +    sifive,fine-ctr-bits: false
> +
>  additionalProperties: false
>  
>  required:
> -- 
> 2.17.1
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Daniel Lezcano <daniel.lezcano@linaro.org>:

On Fri, 21 Mar 2025 16:35:06 +0800 you wrote:
> Add compatible string and property for the SiFive CLINT v2. The SiFive
> CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> in their control methods.
> 
> Signed-off-by: Nick Hu <nick.hu@sifive.com>
> Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> 
> [...]

Here is the summary with links:
  - [v3] dt-bindings: timer: Add SiFive CLINT2
    https://git.kernel.org/riscv/c/0f920690a82c

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Charles Perry]

On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> Add compatible string and property for the SiFive CLINT v2. The SiFive
> CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> in their control methods.

Hello Nick,

Can you help me understand what is this different control method? I've
found that both OpenSBI [1] and U-Boot [2] use the same match data in their
clint driver which would indicate that they are compatible.

Also, do you know if there's an easy way to tell if a sifive clint is a v0
or v2?

Thanks,
Charles

[1]: https://elixir.bootlin.com/opensbi/v1.8.1/source/lib/utils/timer/fdt_timer_mtimer.c#L163
[2]: https://elixir.bootlin.com/u-boot/v2026.01/source/drivers/timer/riscv_aclint_timer.c#L86

> 
> Signed-off-by: Nick Hu <nick.hu@sifive.com>
> Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> ---
> - v3 changes:
>   - Add the reason for the incompatibility between sifive,clint2 and
>     sifive,clint0.
> - v2 changes:
>   - Don't allow sifive,clint2 by itself. Add '-{}' to the first entry
>   - Mark the sifive,fine-ctr-bits as the required property when
>     the compatible includes the sifive,clint2
> 
>  .../bindings/timer/sifive,clint.yaml          | 22 +++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> index 76d83aea4e2b..34684cda8b15 100644
> --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> @@ -36,6 +36,12 @@ properties:
>                - starfive,jh7110-clint   # StarFive JH7110
>                - starfive,jh8100-clint   # StarFive JH8100
>            - const: sifive,clint0        # SiFive CLINT v0 IP block
> +      - items:
> +          - {}
> +          - const: sifive,clint2        # SiFive CLINT v2 IP block
> +        description:
> +          SiFive CLINT v2 is the HRT that supports the Zicntr. The control of sifive,clint2
> +          differs from that of sifive,clint0, making them incompatible.
>        - items:
>            - enum:
>                - allwinner,sun20i-d1-clint
> @@ -62,6 +68,22 @@ properties:
>      minItems: 1
>      maxItems: 4095
>  
> +  sifive,fine-ctr-bits:
> +    maximum: 15
> +    description: The width in bits of the fine counter.
> +
> +if:
> +  properties:
> +    compatible:
> +      contains:
> +        const: sifive,clint2
> +then:
> +  required:
> +    - sifive,fine-ctr-bits
> +else:
> +  properties:
> +    sifive,fine-ctr-bits: false
> +
>  additionalProperties: false
>  
>  required:
> -- 
> 2.17.1
> 
> 

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 3448 bytes --]

On Thu, Mar 26, 2026 at 01:55:38PM -0700, Charles Perry wrote:
> On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> > Add compatible string and property for the SiFive CLINT v2. The SiFive
> > CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> > in their control methods.
> 
> Hello Nick,
> 
> Can you help me understand what is this different control method? I've
> found that both OpenSBI [1] and U-Boot [2] use the same match data in their
> clint driver which would indicate that they are compatible.

Hmm, good point. I didn't see that the drivers were not doing anything
different. I guess really the clintv2 should fall back to the clintv0,
and the difference in hardware should be elaborated on.

I think I also dropped the ball on sifive,fine-ctr-bits, and that should
be removed and the counter width determined from the compatible.
There's no users for that yet I think, and there's no valid users of the
clintv2 compatible /at all/ so maybe it can just get culled.

> 
> Also, do you know if there's an easy way to tell if a sifive clint is a v0
> or v2?
> 
> Thanks,
> Charles
> 
> [1]: https://elixir.bootlin.com/opensbi/v1.8.1/source/lib/utils/timer/fdt_timer_mtimer.c#L163
> [2]: https://elixir.bootlin.com/u-boot/v2026.01/source/drivers/timer/riscv_aclint_timer.c#L86
> 
> > 
> > Signed-off-by: Nick Hu <nick.hu@sifive.com>
> > Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> > ---
> > - v3 changes:
> >   - Add the reason for the incompatibility between sifive,clint2 and
> >     sifive,clint0.
> > - v2 changes:
> >   - Don't allow sifive,clint2 by itself. Add '-{}' to the first entry
> >   - Mark the sifive,fine-ctr-bits as the required property when
> >     the compatible includes the sifive,clint2
> > 
> >  .../bindings/timer/sifive,clint.yaml          | 22 +++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > index 76d83aea4e2b..34684cda8b15 100644
> > --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > @@ -36,6 +36,12 @@ properties:
> >                - starfive,jh7110-clint   # StarFive JH7110
> >                - starfive,jh8100-clint   # StarFive JH8100
> >            - const: sifive,clint0        # SiFive CLINT v0 IP block
> > +      - items:
> > +          - {}
> > +          - const: sifive,clint2        # SiFive CLINT v2 IP block
> > +        description:
> > +          SiFive CLINT v2 is the HRT that supports the Zicntr. The control of sifive,clint2
> > +          differs from that of sifive,clint0, making them incompatible.
> >        - items:
> >            - enum:
> >                - allwinner,sun20i-d1-clint
> > @@ -62,6 +68,22 @@ properties:
> >      minItems: 1
> >      maxItems: 4095
> >  
> > +  sifive,fine-ctr-bits:
> > +    maximum: 15
> > +    description: The width in bits of the fine counter.
> > +
> > +if:
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        const: sifive,clint2
> > +then:
> > +  required:
> > +    - sifive,fine-ctr-bits
> > +else:
> > +  properties:
> > +    sifive,fine-ctr-bits: false
> > +
> >  additionalProperties: false
> >  
> >  required:
> > -- 
> > 2.17.1
> > 
> > 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Nick Hu]

On Fri, Mar 27, 2026 at 4:56 AM Charles Perry
<charles.perry@microchip.com> wrote:
>
> On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> > Add compatible string and property for the SiFive CLINT v2. The SiFive
> > CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> > in their control methods.
>
> Hello Nick,
>
> Can you help me understand what is this different control method? I've
> found that both OpenSBI [1] and U-Boot [2] use the same match data in their
> clint driver which would indicate that they are compatible.
>
Sorry for the late reply.
Unlike v0, v2 requires a write to the mtime register to kick the timer.

> Also, do you know if there's an easy way to tell if a sifive clint is a v0
> or v2?
>
sifive,clint2 introduces additional MMIO registers

> Thanks,
> Charles
>
> [1]: https://elixir.bootlin.com/opensbi/v1.8.1/source/lib/utils/timer/fdt_timer_mtimer.c#L163
> [2]: https://elixir.bootlin.com/u-boot/v2026.01/source/drivers/timer/riscv_aclint_timer.c#L86
>
> >
> > Signed-off-by: Nick Hu <nick.hu@sifive.com>
> > Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> > ---
> > - v3 changes:
> >   - Add the reason for the incompatibility between sifive,clint2 and
> >     sifive,clint0.
> > - v2 changes:
> >   - Don't allow sifive,clint2 by itself. Add '-{}' to the first entry
> >   - Mark the sifive,fine-ctr-bits as the required property when
> >     the compatible includes the sifive,clint2
> >
> >  .../bindings/timer/sifive,clint.yaml          | 22 +++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > index 76d83aea4e2b..34684cda8b15 100644
> > --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > @@ -36,6 +36,12 @@ properties:
> >                - starfive,jh7110-clint   # StarFive JH7110
> >                - starfive,jh8100-clint   # StarFive JH8100
> >            - const: sifive,clint0        # SiFive CLINT v0 IP block
> > +      - items:
> > +          - {}
> > +          - const: sifive,clint2        # SiFive CLINT v2 IP block
> > +        description:
> > +          SiFive CLINT v2 is the HRT that supports the Zicntr. The control of sifive,clint2
> > +          differs from that of sifive,clint0, making them incompatible.
> >        - items:
> >            - enum:
> >                - allwinner,sun20i-d1-clint
> > @@ -62,6 +68,22 @@ properties:
> >      minItems: 1
> >      maxItems: 4095
> >
> > +  sifive,fine-ctr-bits:
> > +    maximum: 15
> > +    description: The width in bits of the fine counter.
> > +
> > +if:
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        const: sifive,clint2
> > +then:
> > +  required:
> > +    - sifive,fine-ctr-bits
> > +else:
> > +  properties:
> > +    sifive,fine-ctr-bits: false
> > +
> >  additionalProperties: false
> >
> >  required:
> > --
> > 2.17.1
> >
> >

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Charles Perry]

On Wed, Apr 08, 2026 at 02:15:19PM +0800, Nick Hu wrote:
> On Fri, Mar 27, 2026 at 4:56 AM Charles Perry
> <charles.perry@microchip.com> wrote:
> >
> > On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> > > Add compatible string and property for the SiFive CLINT v2. The SiFive
> > > CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> > > in their control methods.
> >
> > Hello Nick,
> >
> > Can you help me understand what is this different control method? I've
> > found that both OpenSBI [1] and U-Boot [2] use the same match data in their
> > clint driver which would indicate that they are compatible.
> >
> Sorry for the late reply.

Hello Nick, no worries.

> Unlike v0, v2 requires a write to the mtime register to kick the timer.

A kick once at the beginning or every time a machine timer interrupt fires?

> 
> > Also, do you know if there's an easy way to tell if a sifive clint is a v0
> > or v2?
> >
> sifive,clint2 introduces additional MMIO registers

Is that the high resolution timers (HRT) mentionned in the description?

And last question, would you happen to know if sifive made a clint v1 that
does NOT require the mtime kick but does have the HRT?

I'm trying to figure out what should be the compatible for PIC64-HPSC.
Some code from a repository called "FSFM" used "sifive,clint1" for the
compatible. I'm wondering if I should add the clint v1 to this file.

Thanks,
Charles

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Nick Hu]

On Tue, Mar 31, 2026 at 12:16 AM Conor Dooley <conor@kernel.org> wrote:
>
> On Thu, Mar 26, 2026 at 01:55:38PM -0700, Charles Perry wrote:
> > On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> > > Add compatible string and property for the SiFive CLINT v2. The SiFive
> > > CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> > > in their control methods.
> >
> > Hello Nick,
> >
> > Can you help me understand what is this different control method? I've
> > found that both OpenSBI [1] and U-Boot [2] use the same match data in their
> > clint driver which would indicate that they are compatible.
>
> Hmm, good point. I didn't see that the drivers were not doing anything
> different. I guess really the clintv2 should fall back to the clintv0,
> and the difference in hardware should be elaborated on.
>
> I think I also dropped the ball on sifive,fine-ctr-bits, and that should
> be removed and the counter width determined from the compatible.
> There's no users for that yet I think, and there's no valid users of the
> clintv2 compatible /at all/ so maybe it can just get culled.
>
Thanks for pointing that out, I'll send a patch to remove the
sifive,fine-ctr-bits property.


> >
> > Also, do you know if there's an easy way to tell if a sifive clint is a v0
> > or v2?
> >
> > Thanks,
> > Charles
> >
> > [1]: https://elixir.bootlin.com/opensbi/v1.8.1/source/lib/utils/timer/fdt_timer_mtimer.c#L163
> > [2]: https://elixir.bootlin.com/u-boot/v2026.01/source/drivers/timer/riscv_aclint_timer.c#L86
> >
> > >
> > > Signed-off-by: Nick Hu <nick.hu@sifive.com>
> > > Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> > > ---
> > > - v3 changes:
> > >   - Add the reason for the incompatibility between sifive,clint2 and
> > >     sifive,clint0.
> > > - v2 changes:
> > >   - Don't allow sifive,clint2 by itself. Add '-{}' to the first entry
> > >   - Mark the sifive,fine-ctr-bits as the required property when
> > >     the compatible includes the sifive,clint2
> > >
> > >  .../bindings/timer/sifive,clint.yaml          | 22 +++++++++++++++++++
> > >  1 file changed, 22 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > > index 76d83aea4e2b..34684cda8b15 100644
> > > --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > > +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > > @@ -36,6 +36,12 @@ properties:
> > >                - starfive,jh7110-clint   # StarFive JH7110
> > >                - starfive,jh8100-clint   # StarFive JH8100
> > >            - const: sifive,clint0        # SiFive CLINT v0 IP block
> > > +      - items:
> > > +          - {}
> > > +          - const: sifive,clint2        # SiFive CLINT v2 IP block
> > > +        description:
> > > +          SiFive CLINT v2 is the HRT that supports the Zicntr. The control of sifive,clint2
> > > +          differs from that of sifive,clint0, making them incompatible.
> > >        - items:
> > >            - enum:
> > >                - allwinner,sun20i-d1-clint
> > > @@ -62,6 +68,22 @@ properties:
> > >      minItems: 1
> > >      maxItems: 4095
> > >
> > > +  sifive,fine-ctr-bits:
> > > +    maximum: 15
> > > +    description: The width in bits of the fine counter.
> > > +
> > > +if:
> > > +  properties:
> > > +    compatible:
> > > +      contains:
> > > +        const: sifive,clint2
> > > +then:
> > > +  required:
> > > +    - sifive,fine-ctr-bits
> > > +else:
> > > +  properties:
> > > +    sifive,fine-ctr-bits: false
> > > +
> > >  additionalProperties: false
> > >
> > >  required:
> > > --
> > > 2.17.1
> > >
> > >

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Nick Hu]

On Wed, Apr 8, 2026 at 10:41 PM Charles Perry
<charles.perry@microchip.com> wrote:
>
> On Wed, Apr 08, 2026 at 02:15:19PM +0800, Nick Hu wrote:
> > On Fri, Mar 27, 2026 at 4:56 AM Charles Perry
> > <charles.perry@microchip.com> wrote:
> > >
> > > On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> > > > Add compatible string and property for the SiFive CLINT v2. The SiFive
> > > > CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> > > > in their control methods.
> > >
> > > Hello Nick,
> > >
> > > Can you help me understand what is this different control method? I've
> > > found that both OpenSBI [1] and U-Boot [2] use the same match data in their
> > > clint driver which would indicate that they are compatible.
> > >
> > Sorry for the late reply.
>
> Hello Nick, no worries.
>
> > Unlike v0, v2 requires a write to the mtime register to kick the timer.
>
> A kick once at the beginning or every time a machine timer interrupt fires?
>
A kick once at the beginning

> >
> > > Also, do you know if there's an easy way to tell if a sifive clint is a v0
> > > or v2?
> > >
> > sifive,clint2 introduces additional MMIO registers
>
> Is that the high resolution timers (HRT) mentionned in the description?
>
> And last question, would you happen to know if sifive made a clint v1 that
> does NOT require the mtime kick but does have the HRT?
>
Yes, that's correct.

> I'm trying to figure out what should be the compatible for PIC64-HPSC.
> Some code from a repository called "FSFM" used "sifive,clint1" for the
> compatible. I'm wondering if I should add the clint v1 to this file.
>
> Thanks,
> Charles
>

Re: [PATCH v3] dt-bindings: timer: Add SiFive CLINT2

[Charles Perry]

On Thu, Apr 09, 2026 at 01:37:46PM +0800, Nick Hu wrote:
> On Wed, Apr 8, 2026 at 10:41 PM Charles Perry
> <charles.perry@microchip.com> wrote:
> >
> > On Wed, Apr 08, 2026 at 02:15:19PM +0800, Nick Hu wrote:
> > > On Fri, Mar 27, 2026 at 4:56 AM Charles Perry
> > > <charles.perry@microchip.com> wrote:
> > > >
> > > > On Fri, Mar 21, 2025 at 04:35:06PM +0800, Nick Hu wrote:
> > > > > Add compatible string and property for the SiFive CLINT v2. The SiFive
> > > > > CLINT v2 is incompatible with the SiFive CLINT v0 due to differences
> > > > > in their control methods.
> > > >
> > > > Hello Nick,
> > > >
> > > > Can you help me understand what is this different control method? I've
> > > > found that both OpenSBI [1] and U-Boot [2] use the same match data in their
> > > > clint driver which would indicate that they are compatible.
> > > >
> > > Sorry for the late reply.
> >
> > Hello Nick, no worries.
> >
> > > Unlike v0, v2 requires a write to the mtime register to kick the timer.
> >
> > A kick once at the beginning or every time a machine timer interrupt fires?
> >
> A kick once at the beginning

That would explain what I observed in U-Boot and OpenSBI. The kick might be
in some arch specific code or a prior boot stage.

> 
> > >
> > > > Also, do you know if there's an easy way to tell if a sifive clint is a v0
> > > > or v2?
> > > >
> > > sifive,clint2 introduces additional MMIO registers
> >
> > Is that the high resolution timers (HRT) mentionned in the description?
> >
> > And last question, would you happen to know if sifive made a clint v1 that
> > does NOT require the mtime kick but does have the HRT?
> >
> Yes, that's correct.

Ok.

Thanks,
Charles

> 
> > I'm trying to figure out what should be the compatible for PIC64-HPSC.
> > Some code from a repository called "FSFM" used "sifive,clint1" for the
> > compatible. I'm wondering if I should add the clint v1 to this file.
> >
> > Thanks,
> > Charles
> >