[PATCH v3 4/7] dt-bindings: Add RISC-V misaligned access performance

Evan Green
2023-02-21T20:02:15Z

From: Palmer Dabbelt <palmer@rivosinc.com>

This key allows device trees to specify the performance of misaligned
accesses to main memory regions from each CPU in the system.

Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Evan Green <evan@rivosinc.com>
---

Changes in v3:
- Added | to description: to make dt-checker happy.

Documentation/devicetree/bindings/riscv/cpus.yaml | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
index c6720764e765..f79e9e5c5ee9 100644
--- a/Documentation/devicetree/bindings/riscv/cpus.yaml
+++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
@@ -85,6 +85,21 @@ properties:
$ref: "/schemas/types.yaml#/definitions/string"
pattern: ^rv(?:64|32)imaf?d?q?c?b?v?k?h?(?:_[hsxz](?:[a-z])+)*$

+ riscv,misaligned-access-performance:
+ description: |
+ Identifies the performance of misaligned memory accesses to main memory
+ regions. There are three flavors of unaligned access performance: "emulated"
+ means that misaligned accesses are emulated via software and thus
+ extremely slow, "slow" means that misaligned accesses are supported by
+ hardware but still slower that aligned accesses sequences, and "fast"
+ means that misaligned accesses are as fast or faster than the
+ cooresponding aligned accesses sequences.
+ $ref: "/schemas/types.yaml#/definitions/string"
+ enum:
+ - emulated
+ - slow
+ - fast
+
# RISC-V requires 'timebase-frequency' in /cpus, so disallow it here
timebase-frequency: false

--
2.25.1