From 44fcc9f11e80cd4ae0811dc41f8201c5d95dea6b Mon Sep 17 00:00:00 2001
From: Neels Hofmeyr <neels@hofmeyr.de>
Date: Mon, 28 May 2018 14:29:49 +0200
Subject: doc: charts: illustrate new plan for ts and lchans

Add lchan and timeslot FSM charts to illustrate planning of how osmo-bsc should
handle lchan assignment and release.

Modify assignment, handover, lchan-release charts according to the new plan.

Change-Id: I18d60de5ee932c962aad0a532965a55d570bb936
---
 doc/timeslot.msc | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 doc/timeslot.msc

(limited to 'doc/timeslot.msc')

diff --git a/doc/timeslot.msc b/doc/timeslot.msc
new file mode 100644
index 000000000..9a8c36075
--- /dev/null
+++ b/doc/timeslot.msc
@@ -0,0 +1,98 @@
+msc {
+	hscale=2;
+	bts [label="MS/BTS"], bsc[label="BSC"], bsc_ts[label="BSC timeslot FSM"], bsc_lchan[label="BSC lchan FSM"];
+
+	bsc_ts abox bsc_ts [label="NOT_INITIALIZED (no timeout)"];
+
+	...;
+	bsc note bsc_ts [label="OML and RSL may be established in any order"];
+	bts => bsc_ts [label="OML: Channel OPSTART ACK"];
+	bsc -> bsc_ts [label="RSL bootstrapped"];
+	bsc_ts abox bsc_ts [label="UNUSED (no timeout)"];
+
+	|||;
+	bts rbox bsc_lchan [label="UNUSED, onenter"];
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	--- [label="GPRS enabled?"];
+	--- [label="IF: dedicated PDCH?"];
+	bsc_ts abox bsc_ts [label="PDCH (no timeout)"];
+
+	|||;
+	--- [label="IF: dynamic timeslot"];
+	bsc_ts abox bsc_ts [label="WAIT_PDCH_ACT (?s, Tnnnn)"];
+	bts <= bsc_ts [label="RSL Chan Activ of PDCH",ID="Osmocom style"];
+	bts <= bsc_ts [label="RSL PDCH Act",ID="ip.access style"];
+	...;
+	--- [label="timeout:"];
+	bsc_ts abox bsc_ts [label="BORKEN"];
+	---;
+	...;
+	bts => bsc_ts [label="RSL RF Chan Activ ACK",ID="Osmocom style"];
+	bts => bsc_ts [label="RSL PDCH Act ACK",ID="ip.access style"];
+	bsc_ts abox bsc_ts [label="PDCH (no timeout)"];
+
+	--- [label="END: GPRS enabled?"];
+	...;
+	...;
+
+	bts rbox bsc_lchan [label="UNUSED, on event"];
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	bsc_ts <- bsc_lchan [label="TS_EV_LCHAN_REQUESTED (data=lchan)"];
+	bsc_ts abox bsc_ts [label="IN_USE"];
+	bsc_ts -> bsc_lchan [label="LCHAN_EV_TS_READY"];
+	bts <= bsc_lchan [label="RSL Chan Activ (and so on)"];
+	...;
+	bts rbox bsc_lchan [label="IN_USE, second lchan"];
+	bsc_ts <- bsc_lchan [label="TS_EV_LCHAN_REQUESTED (data=lchan)"];
+	bsc_ts -> bsc_lchan [label="LCHAN_EV_TS_READY"];
+	bts <= bsc_lchan [label="RSL Chan Activ (and so on)"];
+	...;
+	...;
+	bts rbox bsc_lchan [label="IN_USE, when lchan FSM releases (both regularly, or due to error)"];
+	bsc_ts <- bsc_lchan [label="TS_EV_LCHAN_UNUSED (data=lchan)"];
+	--- [label="IF all lchan->fi->state == LCHAN_ST_UNUSED"];
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	---;
+	...;
+	...;
+
+
+	bts rbox bsc_lchan [label="PDCH on lchan request"];
+	bsc_ts note bsc_lchan [label="TS_EV_LCHAN_REQUESTED should only come in on
+		lchans where it makes sense, both from TS kind as well as not
+		conflicting with other users of the lchan."];
+
+	bsc_ts <- bsc_lchan [label="TS_EV_LCHAN_REQUESTED"];
+	bsc_ts abox bsc_ts [label="WAIT_PDCH_DEACT (?s, Tnnnn)"];
+	bts <= bsc_ts [label="RSL RF Chan Release of PDCH",ID="Osmocom style"];
+	bts <= bsc_ts [label="RSL PDCH Deact",ID="ip.access style"];
+	...;
+	--- [label="timeout:"];
+	bsc_ts abox bsc_ts [label="BORKEN"];
+	bsc_ts -> bsc_lchan [label="LCHAN_EV_TS_ERROR"];
+	---;
+	...;
+	bts => bsc_ts [label="RSL RF Chan Release ACK",ID="Osmocom style"];
+	bts => bsc_ts [label="RSL PDCH Deact ACK",ID="ip.access style"];
+	--- [label="IF all lchan->fi->state == LCHAN_ST_UNUSED"];
+	bsc_ts note bsc_lchan [label="If the lchan FSM decided to give up in the
+		meantime, nr of active lchans might have dropped back to zero."];
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	bsc_ts note bsc_ts [label="onenter at UNUSED state will trigger back to
+		PDCH mode"];
+	|||;
+	--- [label="IF at least one lchan->state != LCHAN_ST_UNUSED"];
+	bsc_ts abox bsc_ts [label="IN_USE"];
+	bsc_ts rbox bsc_ts [label="Continue at 'IN_USE' above"];
+	...;
+	...;
+
+	bts rbox bsc_lchan [label="on erratic event"];
+	bsc_ts -> bsc_lchan [label="LCHAN_EV_TS_ERROR"];
+	bsc_lchan box bsc_lchan [label="release lchan"];
+	...;
+	bsc_ts <- bsc_lchan [label="TS_EV_LCHAN_UNUSED"];
+	bsc_ts note bsc_ts [label="log error but ignore"];
+	...;
+
+}
-- 
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