[Skiboot] [PATCH 2/2] FSP/CUPD: Code Update OPAL API documentation

[Vasant Hegde]

Add documentation for FSP based machine code update API.

Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
---
 doc/opal-api/opal-code-update-76-77-78.txt |   78 ++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 doc/opal-api/opal-code-update-76-77-78.txt

diff --git a/doc/opal-api/opal-code-update-76-77-78.txt b/doc/opal-api/opal-code-update-76-77-78.txt
new file mode 100644
index 0000000..e7657d1
--- /dev/null
+++ b/doc/opal-api/opal-code-update-76-77-78.txt
@@ -0,0 +1,78 @@
+Code Update on FSP based machine
+================================
+
+There are three OPAL calls for code update on FSP based machine:
+
+ #define OPAL_FLASH_VALIDATE	76
+ #define OPAL_FLASH_MANAGE	77
+ #define OPAL_FLASH_UPDATE	78
+
+OPAL_FLASH_VALIDATE
+-------------------
+  Validate new image is valid for this platform or not. We do below
+  validation in OPAL:
+   - We do below sys parameters validation to confirm inband
+     update is allowed.
+     - Platform is managed by HMC or not?.
+     - Code update policy (inband code update allowed?).
+
+   - We parse candidate image header (first 4k bytes) to perform
+     below validations.
+     - Image magic number.
+     - Image version to confirm image is valid for this platform.
+
+  Input:
+    buffer	: First 4k bytes of new image
+    size	: Input buffer size
+
+  Output:
+    buffer	: Output result (current and new image version details)
+    size	: Output buffer size
+    result	: Token to identify what will happen if update is attempted
+		  See hw/fsp/fsp-codeupdate.h for token values.
+
+  Return value:
+    Validation status
+
+
+OPAL_FLASH_MANAGE
+-----------------
+  Commit/Reject image.
+    - We can commit new image (T -> P), if system is running with T side image.
+    - We can reject T side image, if system is running with P side image.
+
+    Note:
+       If a platform is running from a T side image when an update is to be
+       applied, then the platform may automatically commit the current T side
+       image to the P side to allow the new image to be updated to the
+       temporary image area.
+
+  Input
+     op	: Operation (1 : Commit /0 : Reject)
+
+  Return value:
+    Commit operation status (0 : Success)
+
+OPAL_FLASH_UPDATE
+------------------
+  Update new image. It only sets the flag, actual update happens
+  during system reboot/shutdown.
+
+  Host splits FW image to scatter/gather list and sends it to OPAL.
+  OPAL parse the image to get indivisual LID and passes it to FSP
+  via MBOX command.
+
+  FW update flow :
+    - if (running side == T)
+        Swap P & T side
+    - Start code update
+    - Delete T side LIDs
+    - Write LIDs
+    - Code update complete
+    - Deep IPL
+
+  Input
+    list  : Real address of image scatter/gather list of the FW image
+
+  Return value:
+    Update operation status (0: update requested)