Add obmc-host-shutdown target dependencies

The following information was needed to debug an
issue in the power down path. Since the data was
useful, makes sense to keep in the corresponding doc.

This new section shows all of the targets and services
associated with powering off a system and their
dependencies. It's for a witherspoon system but the
targets and some services are relevant to other systems
as well.

Change-Id: I62ae04814765f20013de15ec0430a4a94bc5f2bf
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/openbmc-systemd.md b/openbmc-systemd.md
index 0864709..f700247 100644
--- a/openbmc-systemd.md
+++ b/openbmc-systemd.md
@@ -163,3 +163,78 @@ is up and running, and the service which toggles the pgood pin is re-executed,
 you're going to crash your system.  Given this info, the goal should always be
 to write "oneshot" services that have RemainAfterExit set to yes.
 
+## Target and Service Dependency Details
+There are some tools available out there to visualize systemd service and
+target dependencies (systemd-analyze) but due to the complexity of our design,
+they do not generate anything very useful.
+
+For now, document the current dependencies on a witherspoon system for
+reference.
+
+```
+R = Requires
+W = Wants
+A = After
+B = Before
+S = Start (runs a command to start another target or service)
+(S) = Synchronization Target
+```
+
+### Soft Power Off
+```
+obmc-host-shutdown.target
+  R: xyz.openbmc_project.Ipmi.Internal.SoftPowerOff.service
+     W: obmc-host-stopping.target (S)
+     B: obmc-host-stopping.target (S)
+  R: obmc-chassis-poweroff.target
+     R: obmc-host-stop.target
+        R: op-occ-disable.service
+           B: obmc-host-stop-pre.target
+     R: op-power-stop.service
+        W: obmc-power-stop.target (S)
+        B: obmc-power-stop.target (S)
+        W: obmc-power-stop-pre.target (S)
+        A: obmc-power-stop-pre.target (S)
+        W: mapper-wait@-org-openbmc-control-power.service
+        A: mapper-wait@-org-openbmc-control-power.service
+     R: op-wait-power-off.service
+        B: obmc-power-off.target (S)
+        W: obmc-power-stop.target (S)
+        B: obmc-power-stop.target (S)
+        W: obmc-power-stop-pre.target (S)
+        A: obmc-power-stop-pre.target (S)
+        W: mapper-wait@-org-openbmc-control-power.service
+        A: mapper-wait@-org-openbmc-control-power.service
+     R: op-powered-off.service
+        A: op-wait-power-off.service
+        R: op-wait-power-off.service
+        S: obmc-chassis-powered-off.target
+     W: pcie-poweroff.service
+        B: op-power-stop.service
+        A: obmc-power-stop-pre@.target
+```
+
+#### Synchronization Target Dependencies
+```
+obmc-power-stop.target
+  W: obmc-power-stop-pre.target
+  A: obmc-power-stop-pre.target
+  W: obmc-standby.target
+
+obmc-power-stop-pre.target
+  W: obmc-host-stopped.target
+  A: obmc-host-stopped.target
+
+obmc-host-stopped.target
+  W: obmc-host-stopping.target
+  A: obmc-host-stopping.target
+  B: obmc-power-stop-pre.target
+
+obmc-host-stopping.target
+  W: obmc-host-stop-pre.target
+  A: obmc-host-stop-pre.target
+  B: obmc-host-stopped.target
+
+obmc-host-stop-pre.target
+  B: obmc-host-stopping.target
+```