Documentation for clear GARD API

This commit adds to the OpenBMC documentation with information about the
API to clear the GARD partition on OpenPOWER systems.

This documentation is placed under host-management.md since the
function manages a record kept by the host.

Resolves openbmc/openbmc#2637

Change-Id: I07c81262b306bdd8b5cf8a06cbb74b0436fc9ba1
Signed-off-by: Michael Tritz <mtritz@us.ibm.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/host-management.md b/host-management.md
index 4567717..2be41e3 100644
--- a/host-management.md
+++ b/host-management.md
@@ -216,3 +216,29 @@ curl -c cjar -b cjar -k -H "Content-Type: application/json" -X PUT \
 
 More information about Host State Management can be found here:
 https://github.com/openbmc/phosphor-dbus-interfaces/tree/master/xyz/openbmc_project/State
+
+Host Clear GARD
+================
+
+On OpenPOWER systems, the host maintains a record of bad or non-working
+components on the GARD partition. This record is referenced by the host on
+subsequent boots to determine which parts should be ignored.
+
+The BMC implements a function that simply clears this partition. This function
+can be called as follows:
+
+  * Method 1: From the BMC command line:
+
+      ```
+      busctl call org.open_power.Software.Host.Updater \
+        /org/open_power/control/gard \
+        xyz.openbmc_project.Common.FactoryReset Reset
+      ```
+
+  * Method 2: Using the REST API:
+
+      ```
+      curl -b cjar -k -H 'Content-Type: application/json' -X POST -d '{"data":[]}' https://${bmc}/org/open_power/control/gard/action/Reset
+      ```
+
+Implementation: https://github.com/openbmc/openpower-pnor-code-mgmt