dt-bindings: riscv: Add Svade and Svadu Entries

Add entries for the Svade and Svadu extensions to the riscv,isa-extensions
property.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20240726084931.28924-3-yongxuan.wang@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>

Author: yong-xuan

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -153,6 +153,34 @@ properties:
             ratified at commit 3f9ed34 ("Add ability to manually trigger
             workflow. (#2)") of riscv-time-compare.
 
+        - const: svade
+          description: |
+            The standard Svade supervisor-level extension for SW-managed PTE A/D
+            bit updates as ratified in the 20240213 version of the privileged
+            ISA specification.
+
+            Both Svade and Svadu extensions control the hardware behavior when
+            the PTE A/D bits need to be set. The default behavior for the four
+            possible combinations of these extensions in the device tree are:
+            1) Neither Svade nor Svadu present in DT => It is technically
+               unknown whether the platform uses Svade or Svadu. Supervisor
+               software should be prepared to handle either hardware updating
+               of the PTE A/D bits or page faults when they need updated.
+            2) Only Svade present in DT => Supervisor must assume Svade to be
+               always enabled.
+            3) Only Svadu present in DT => Supervisor must assume Svadu to be
+               always enabled.
+            4) Both Svade and Svadu present in DT => Supervisor must assume
+               Svadu turned-off at boot time. To use Svadu, supervisor must
+               explicitly enable it using the SBI FWFT extension.
+
+        - const: svadu
+          description: |
+            The standard Svadu supervisor-level extension for hardware updating
+            of PTE A/D bits as ratified in the 20240528 version of the
+            privileged ISA specification. Please refer to Svade dt-binding
+            description for more details.
+
         - const: svinval
           description:
             The standard Svinval supervisor-level extension for fine-grained