diff options
| author | Guodong Xu <guodong@riscstar.com> | 2026-01-10 13:18:18 +0800 |
|---|---|---|
| committer | Conor Dooley <conor.dooley@microchip.com> | 2026-01-13 22:22:56 +0000 |
| commit | 0cdb7fc1879b1b858463125630f4dd5af6b111ad (patch) | |
| tree | d51493eed4cd7188e4b23897aa05ee145e2aa5f9 | |
| parent | fff010c776f715904ba0823bb347eac00dccffa2 (diff) | |
dt-bindings: riscv: Add B ISA extension description
Add description of the single-letter B extension for Bit Manipulation.
B is mandatory for RVA23U64.
The B extension is ratified in the 20240411 version of the unprivileged
ISA specification. According to the ratified spec, the B standard
extension comprises instructions provided by the Zba, Zbb, and Zbs
extensions.
Add two-way dependency check to enforce that B implies Zba/Zbb/Zbs; and
when Zba/Zbb/Zbs (all of them) are specified, then B must be added too.
The reason why B/Zba/Zbb/Zbs must coexist at the same time is that
unlike other single-letter extensions, B was ratified (Apr/2024) much
later than its component extensions Zba/Zbb/Zbs (Jun/2021).
When "b" is specified, zba/zbb/zbs must be present to ensure
backward compatibility with existing software and kernels that only
look for the explicit component strings.
When all three components zba/zbb/zbs are specified, "b" should also be
present. Making "b" mandatory when all three components are present.
Existing devicetrees with zba/zbb/zbs but without "b" will generate
warnings that can be fixed in follow-up patches.
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
| -rw-r--r-- | Documentation/devicetree/bindings/riscv/extensions.yaml | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml index 6a4697b36b8d..beeb6612db31 100644 --- a/Documentation/devicetree/bindings/riscv/extensions.yaml +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml @@ -109,6 +109,13 @@ properties: The standard C extension for compressed instructions, as ratified in the 20191213 version of the unprivileged ISA specification. + - const: b + description: + The standard B extension for bit manipulation instructions, as + ratified in the 20240411 version of the unprivileged ISA + specification. The B standard extension comprises instructions + provided by the Zba, Zbb, and Zbs extensions. + - const: v description: The standard V extension for vector operations, as ratified @@ -738,6 +745,30 @@ properties: then: contains: const: f + # B comprises Zba, Zbb, and Zbs + - if: + contains: + const: b + then: + allOf: + - contains: + const: zba + - contains: + const: zbb + - contains: + const: zbs + # Zba, Zbb, Zbs together require B + - if: + allOf: + - contains: + const: zba + - contains: + const: zbb + - contains: + const: zbs + then: + contains: + const: b # Zcb depends on Zca - if: contains: |