dyn TS: implement pchan switchover logic

In struct gsm_lchan, add dyn.rqd_ref and dyn.rqd_ta. These save the Channel
Requested details across the PDCH deactivation dance.

abis_rsl.c: add static functions:

* dyn_ts_switchover*() for the various stages of switchover between pchans.

* pchan_for_lchant() to derive the desired pchan from the lchan type that was
  set during lchan_alloc().

* rsl_chan_activate_lchan_as_pdch() to compose the simpler RSL CHAN ACT message
  without introducing numerous special cases to the normal RSL CHAN ACT code.

In rsl_chan_activate_lchan(), detect and initiate required pchan switchovers if
requested pchan on a dyn TS differs.

In rsl_rx_rf_chan_rel_ack(), initiate or continue pchan switchovers after a
channel was released.

In rsl_rx_chan_act_ack(), notice that a switchover is complete.

In chan_alloc.c, add ts_subslots(): abis_rsl.c will need to know the number of
subslots per pchan, to verify that all lchans are free before dyn TS
switchover. The subslots_per_pchan[] array is static to lchan_alloc.c, and
since we need a non-trivial check for dyn TS anyway, add public ts_subslots()
to lchan_alloc.c, which also checks the current dyn pchan type.

Change-Id: I5c6bce13092a10204113d84678c587c65e35e4fd

1 files changed, 2 insertions, 0 deletions

diff --git a/openbsc/include/openbsc/chan_alloc.h b/openbsc/include/openbsc/chan_alloc.h
index 78242e5b7..3e03b97d0 100644
--- a/openbsc/include/openbsc/chan_alloc.h
+++ b/openbsc/include/openbsc/chan_alloc.h
@@ -51,4 +51,6 @@ void network_chan_load(struct pchan_load *pl, struct gsm_network *net);
 
 int trx_is_usable(struct gsm_bts_trx *trx);
 
+uint8_t ts_subslots(struct gsm_bts_trx_ts *ts);
+
 #endif /* _CHAN_ALLOC_H */