diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/osmo-bts-trx/l1_if.h | 44 | ||||
-rw-r--r-- | src/osmo-bts-trx/main.c | 4 | ||||
-rw-r--r-- | src/osmo-bts-trx/scheduler_trx.c | 48 |
3 files changed, 52 insertions, 44 deletions
diff --git a/src/osmo-bts-trx/l1_if.h b/src/osmo-bts-trx/l1_if.h index 87df951b..29bd2468 100644 --- a/src/osmo-bts-trx/l1_if.h +++ b/src/osmo-bts-trx/l1_if.h @@ -5,6 +5,50 @@ #include <osmo-bts/phy_link.h> #include "trx_if.h" +/* + * TRX frame clock handling + * + * In a "normal" synchronous PHY layer, we would be polled every time + * the PHY needs data for a given frame number. However, the + * OpenBTS-inherited TRX protocol works differently: We (L1) must + * autonomously send burst data based on our own clock, and every so + * often (currently every ~ 216 frames), we get a clock indication from + * the TRX. + * + * We're using a MONOTONIC timerfd interval timer for the 4.615ms frame + * intervals, and then compute + send the 8 bursts for that frame. + * + * Upon receiving a clock indication from the TRX, we compensate + * accordingly: If we were transmitting too fast, we're delaying the + * next interval timer accordingly. If we were too slow, we immediately + * send burst data for the missing frame numbers. + */ + +/*! clock state of a given TRX */ +struct osmo_trx_clock_state { + /*! number of FN periods without TRX clock indication */ + uint32_t fn_without_clock_ind; + struct { + /*! last FN we processed based on FN period timer */ + uint32_t fn; + /*! time at which we last processed FN */ + struct timespec tv; + } last_fn_timer; + struct { + /*! last FN we received a clock indication for */ + uint32_t fn; + /*! time at which we received the last clock indication */ + struct timespec tv; + } last_clk_ind; + /*! Osmocom FD wrapper for timerfd */ + struct osmo_fd fn_timer_ofd; +}; + +/* gsm_bts->model_priv, specific to osmo-bts-trx */ +struct bts_trx_priv { + struct osmo_trx_clock_state clk_s; +}; + struct trx_config { uint8_t trxd_hdr_ver_req; /* requested TRXD header version */ uint8_t trxd_hdr_ver_use; /* actual TRXD header version in use */ diff --git a/src/osmo-bts-trx/main.c b/src/osmo-bts-trx/main.c index b1fa2079..cf40ea3f 100644 --- a/src/osmo-bts-trx/main.c +++ b/src/osmo-bts-trx/main.c @@ -97,6 +97,10 @@ int bts_model_handle_options(int argc, char **argv) int bts_model_init(struct gsm_bts *bts) { + struct bts_trx_priv *bts_trx = talloc_zero(bts, struct bts_trx_priv); + bts_trx->clk_s.fn_timer_ofd.fd = -1; + + bts->model_priv = bts_trx; bts->variant = BTS_OSMO_TRX; bts->support.ciphers = CIPHER_A5(1) | CIPHER_A5(2) | CIPHER_A5(3); diff --git a/src/osmo-bts-trx/scheduler_trx.c b/src/osmo-bts-trx/scheduler_trx.c index 421cf16d..ac34a112 100644 --- a/src/osmo-bts-trx/scheduler_trx.c +++ b/src/osmo-bts-trx/scheduler_trx.c @@ -1581,48 +1581,6 @@ static int trx_sched_fn(struct gsm_bts *bts, uint32_t fn) return 0; } -/* - * TRX frame clock handling - * - * In a "normal" synchronous PHY layer, we would be polled every time - * the PHY needs data for a given frame number. However, the - * OpenBTS-inherited TRX protocol works differently: We (L1) must - * autonomously send burst data based on our own clock, and every so - * often (currently every ~ 216 frames), we get a clock indication from - * the TRX. - * - * We're using a MONOTONIC timerfd interval timer for the 4.615ms frame - * intervals, and then compute + send the 8 bursts for that frame. - * - * Upon receiving a clock indication from the TRX, we compensate - * accordingly: If we were transmitting too fast, we're delaying the - * next interval timer accordingly. If we were too slow, we immediately - * send burst data for the missing frame numbers. - */ - -/*! clock state of a given TRX */ -struct osmo_trx_clock_state { - /*! number of FN periods without TRX clock indication */ - uint32_t fn_without_clock_ind; - struct { - /*! last FN we processed based on FN period timer */ - uint32_t fn; - /*! time at which we last processed FN */ - struct timespec tv; - } last_fn_timer; - struct { - /*! last FN we received a clock indication for */ - uint32_t fn; - /*! time at which we received the last clock indication */ - struct timespec tv; - } last_clk_ind; - /*! Osmocom FD wrapper for timerfd */ - struct osmo_fd fn_timer_ofd; -}; - -/* TODO: This must go and become part of the phy_link */ -static struct osmo_trx_clock_state g_clk_s = { .fn_timer_ofd.fd = -1 }; - /*! duration of a GSM frame in nano-seconds. (120ms/26) */ #define FRAME_DURATION_nS 4615384 /*! duration of a GSM frame in micro-seconds (120s/26) */ @@ -1666,7 +1624,8 @@ extern int quit; static int trx_fn_timer_cb(struct osmo_fd *ofd, unsigned int what) { struct gsm_bts *bts = ofd->data; - struct osmo_trx_clock_state *tcs = &g_clk_s; + struct bts_trx_priv *bts_trx = (struct bts_trx_priv *)bts->model_priv; + struct osmo_trx_clock_state *tcs = &bts_trx->clk_s; struct timespec tv_now; uint64_t expire_count; int64_t elapsed_us, error_us; @@ -1749,7 +1708,8 @@ static int trx_setup_clock(struct gsm_bts *bts, struct osmo_trx_clock_state *tcs /*! called every time we receive a clock indication from TRX */ int trx_sched_clock(struct gsm_bts *bts, uint32_t fn) { - struct osmo_trx_clock_state *tcs = &g_clk_s; + struct bts_trx_priv *bts_trx = (struct bts_trx_priv *)bts->model_priv; + struct osmo_trx_clock_state *tcs = &bts_trx->clk_s; struct timespec tv_now; int elapsed_fn; int64_t elapsed_us, elapsed_us_since_clk, elapsed_fn_since_clk, error_us_since_clk; |