[Skiboot] [PATCH 3/3] doc/opal-api: flesh out return-codes documentation

[Stewart Smith]

Signed-off-by: Stewart Smith <stewart at linux.ibm.com>
---
 doc/opal-api/return-codes.rst | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/doc/opal-api/return-codes.rst b/doc/opal-api/return-codes.rst
index 3ea4a3d85169..8378ee1b6b0c 100644
--- a/doc/opal-api/return-codes.rst
+++ b/doc/opal-api/return-codes.rst
@@ -111,7 +111,10 @@ OPAL_RESOURCE
 
    #define OPAL_RESOURCE		-10
 
-**FIXME**
+When trying to use a limited resource, OPAL found that there were none free.
+While OPAL_BUSY indicates that OPAL may soon be able to proces the requent,
+OPAL_RESOURCE is a more permanent error and while the resource *may* become
+available again in the future, it is not certain that it will.
 
 OPAL_INTERNAL_ERROR
 -------------------
@@ -119,7 +122,8 @@ OPAL_INTERNAL_ERROR
 
    #define OPAL_INTERNAL_ERROR	-11
 
-**FIXME**
+Something has gone wrong inside OPAL. This is likely a bug somewhere and we
+return OPAL_INTERNAL_ERROR for safety.
 
 OPAL_BUSY_EVENT
 ---------------
@@ -142,6 +146,10 @@ OPAL_WRONG_STATE
 
    #define OPAL_WRONG_STATE	-14
 
+The requested operation requires a (hardware or software) component to be in
+a different state. For example, you cannot call OPAL_START_CPU on a CPU that
+is not currently in OPAL.
+
 OPAL_ASYNC_COMPLETION
 ---------------------
 ::
@@ -165,6 +173,10 @@ OPAL_EMPTY
 
    #define OPAL_EMPTY		-16
 
+The call was successful and the correct result is empty. For example, the
+OPAL_IPMI_RECV call can succeed and return that there is no waiting IPMI
+message.
+
 I2C Calls
 ---------
 Added for I2C, only applicable to I2C calls: ::
-- 
2.14.3