[PATCH v4 9/9] docs: document WID DT properties

[Yu-Chien Peter Lin <peter.lin@sifive.com>]

Add "wid" and "widdeleg" properties to domain instance node
documentation and example DT. Add a "Root Domain Node" section
describing the "root" subnode under the domain configuration
node for root domain WID configuration

Signed-off-by: Yu-Chien Peter Lin <peter.lin@sifive.com>
---
Change v3->v4:
- Make compatible string mandatory for root node
- Drop RB-tag from Oza
---
 docs/domain_support.md | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/docs/domain_support.md b/docs/domain_support.md
index 51737218..ed62a6cd 100644
--- a/docs/domain_support.md
+++ b/docs/domain_support.md
@@ -56,6 +56,8 @@ has following details:
   domain. This can be either S-mode or U-mode.
 * **system_reset_allowed** - Is domain allowed to reset the system?
 * **system_suspend_allowed** - Is domain allowed to suspend the system?
+* **wid** - World ID for the domain
+* **widdeleg** - World ID delegation bitmask for the domain
 
 The memory regions represented by **regions** in **struct sbi_domain** have
 following additional constraints to align with RISC-V PMP requirements:
@@ -98,6 +100,8 @@ following manner:
   is the next mode for the ROOT domain
 * **system_reset_allowed** - The ROOT domain is allowed to reset the system
 * **system_suspend_allowed** - The ROOT domain is allowed to suspend the system
+* **wid** - Configurable World ID for the ROOT domain
+* **widdeleg** - Configurable World ID delegation bitmask for the ROOT domain
 
 Domain Effects
 --------------
@@ -131,6 +135,23 @@ The DT properties of a domain configuration DT node are as follows:
 * **compatible** (Mandatory) - The compatible string of the domain
   configuration. This DT property should have value *"opensbi,domain,config"*
 
+### Root Domain Node
+
+The root domain WID configuration is described in a **root** subnode under
+the domain configuration DT node.
+
+The DT properties of the root domain node are as follows:
+
+* **compatible** (Mandatory) - The compatible string of the root domain node.
+  This DT property should have value *"opensbi,domain,instance"*.
+* **wid** (Mandatory if Smlwid is present) - The 32-bit World ID for
+  lower-privilege modes (S/U-mode) for the ROOT domain. If the hart
+  supports the Smlwid extension, this property must be provided.
+* **widdeleg** (Optional) - The 64 bit World ID delegation bitmask for
+  the ROOT domain. If present, OpenSBI writes this value to **mwiddeleg**
+  when entering the ROOT domain (requires Smwiddeleg extension). If absent,
+  clears **mwiddeleg** to disable S-mode WID delegation.
+
 ### Domain Memory Region Node
 
 The domain memory region DT node describes details of a memory region and
@@ -205,6 +226,13 @@ The DT properties of a domain instance DT node are as follows:
   whether the domain instance is allowed to do system reset.
 * **system-suspend-allowed** (Optional) - A boolean flag representing
   whether the domain instance is allowed to do system suspend.
+* **wid** (Mandatory if Smlwid is present) - The 32-bit World ID for
+  lower-privilege modes (S/U-mode) for the domain instance. If the hart
+  supports the Smlwid extension, this property must be provided.
+* **widdeleg** (Optional) - The 64 bit World ID delegation bitmask for
+  the domain instance. If present, OpenSBI writes this value to **mwiddeleg**
+  on context switch into this domain (requires Smwiddeleg extension). If absent,
+  clears **mwiddeleg** to disable S-mode WID delegation.
 
 ### Assigning HART To Domain Instance
 
@@ -260,6 +288,12 @@ be done:
                 order = <64>;
             };
 
+            root {
+                compatible = "opensbi,domain,instance";
+                wid = <3>;
+                widdeleg = <0x0 0x0>;
+            };
+
             tdomain: trusted-domain {
                 compatible = "opensbi,domain,instance";
                 possible-harts = <&cpu0>;
@@ -268,6 +302,8 @@ be done:
                 next-arg1 = <0x0 0x0>;
                 next-addr = <0x0 0x80100000>;
                 next-mode = <0x0>;
+                wid = <1>;
+                widdeleg = <0x0 0x6>;
                 system-reset-allowed;
                 system-suspend-allowed;
             };
@@ -276,6 +312,8 @@ be done:
                 compatible = "opensbi,domain,instance";
                 possible-harts = <&cpu1 &cpu2 &cpu3 &cpu4>;
                 regions = <&tmem 0x0>, <&tuart 0x0>, <&allmem 0x3f>;
+                wid = <0>;
+                widdeleg = <0x0 0x1>;
             };
         };
     };
-- 
2.43.7


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