1 /* GSM LAPDm (TS 04.06) implementation */
3 /* (C) 2010-2011 by Harald Welte <laforge@gnumonks.org>
4 * (C) 2010 by Andreas Eversberg <jolly@eversberg.eu>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
24 /* Notes on Buffering: rcv_buffer, tx_queue, tx_hist, send_buffer, send_queue
26 * RX data is stored in the rcv_buffer (pointer). If the message is complete, it
27 * is removed from rcv_buffer pointer and forwarded to L3. If the RX data is
28 * received while there is an incomplete rcv_buffer, it is appended to it.
30 * TX data is stored in the send_queue first. When transmitting a frame,
31 * the first message in the send_queue is moved to the send_buffer. There it
32 * resides until all fragments are acknowledged. Fragments to be sent by I
33 * frames are stored in the tx_hist buffer for resend, if required. Also the
34 * current fragment is copied into the tx_queue. There it resides until it is
35 * forwarded to layer 1.
37 * In case we have SAPI 0, we only have a window size of 1, so the unack-
38 * nowledged message resides always in the send_buffer. In case of a suspend,
39 * it can be written back to the first position of the send_queue.
41 * The layer 1 normally sends a PH-READY-TO-SEND. But because we use
42 * asynchronous transfer between layer 1 and layer 2 (serial link), we must
43 * send a frame before layer 1 reaches the right timeslot to send it. So we
44 * move the tx_queue to layer 1 when there is not already a pending frame, and
45 * wait until acknowledge after the frame has been sent. If we receive an
46 * acknowledge, we can send the next frame from the buffer, if any.
48 * The moving of tx_queue to layer 1 may also trigger T200, if desired. Also it
49 * will trigger next I frame, if possible.
57 #include <arpa/inet.h>
59 #include <osmocom/core/logging.h>
60 #include <osmocom/core/timer.h>
61 #include <osmocom/core/msgb.h>
62 #include <osmocom/core/utils.h>
64 #include <osmocom/gsm/tlv.h>
65 #include <osmocom/gsm/rsl.h>
66 #include <osmocom/gsm/prim.h>
67 #include <osmocom/gsm/gsm_utils.h>
68 #include <osmocom/gsm/lapdm.h>
70 #include <osmocom/gsm/protocol/gsm_04_08.h>
71 #include <osmocom/gsm/protocol/gsm_08_58.h>
73 /* TS 04.06 Figure 4 / Section 3.2 */
74 #define LAPDm_LPD_NORMAL 0
75 #define LAPDm_LPD_SMSCB 1
76 #define LAPDm_SAPI_NORMAL 0
77 #define LAPDm_SAPI_SMS 3
78 #define LAPDm_ADDR(lpd, sapi, cr) ((((lpd) & 0x3) << 5) | (((sapi) & 0x7) << 2) | (((cr) & 0x1) << 1) | 0x1)
80 #define LAPDm_ADDR_SAPI(addr) (((addr) >> 2) & 0x7)
81 #define LAPDm_ADDR_CR(addr) (((addr) >> 1) & 0x1)
82 #define LAPDm_ADDR_EA(addr) ((addr) & 0x1)
84 /* TS 04.06 Table 3 / Section 3.4.3 */
85 #define LAPDm_CTRL_I(nr, ns, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((ns) & 0x7) << 1))
86 #define LAPDm_CTRL_S(nr, s, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((s) & 0x3) << 2) | 0x1)
87 #define LAPDm_CTRL_U(u, p) ((((u) & 0x1c) << (5-2)) | (((p) & 0x1) << 4) | (((u) & 0x3) << 2) | 0x3)
89 #define LAPDm_CTRL_is_I(ctrl) (((ctrl) & 0x1) == 0)
90 #define LAPDm_CTRL_is_S(ctrl) (((ctrl) & 0x3) == 1)
91 #define LAPDm_CTRL_is_U(ctrl) (((ctrl) & 0x3) == 3)
93 #define LAPDm_CTRL_U_BITS(ctrl) ((((ctrl) & 0xC) >> 2) | ((ctrl) & 0xE0) >> 3)
94 #define LAPDm_CTRL_PF_BIT(ctrl) (((ctrl) >> 4) & 0x1)
96 #define LAPDm_CTRL_S_BITS(ctrl) (((ctrl) & 0xC) >> 2)
98 #define LAPDm_CTRL_I_Ns(ctrl) (((ctrl) & 0xE) >> 1)
99 #define LAPDm_CTRL_Nr(ctrl) (((ctrl) & 0xE0) >> 5)
101 /* TS 04.06 Table 4 / Section 3.8.1 */
102 #define LAPDm_U_SABM 0x7
103 #define LAPDm_U_DM 0x3
104 #define LAPDm_U_UI 0x0
105 #define LAPDm_U_DISC 0x8
106 #define LAPDm_U_UA 0xC
108 #define LAPDm_S_RR 0x0
109 #define LAPDm_S_RNR 0x1
110 #define LAPDm_S_REJ 0x2
112 #define LAPDm_LEN(len) ((len << 2) | 0x1)
113 #define LAPDm_MORE 0x2
115 /* TS 04.06 Section 5.8.3 */
116 #define N201_AB_SACCH 18
117 #define N201_AB_SDCCH 20
118 #define N201_AB_FACCH 20
120 #define N201_Bter_SACCH 21
121 #define N201_Bter_SDCCH 23
122 #define N201_Bter_FACCH 23
125 /* 5.8.2.1 N200 during establish and release */
126 #define N200_EST_REL 5
127 /* 5.8.2.1 N200 during timer recovery state */
128 #define N200_TR_SACCH 5
129 #define N200_TR_SDCCH 23
130 #define N200_TR_FACCH_FR 34
131 #define N200_TR_EFACCH_FR 48
132 #define N200_TR_FACCH_HR 29
133 /* FIXME: this depends on chan type */
134 #define N200 N200_TR_SACCH
136 #define CR_MS2BS_CMD 0
137 #define CR_MS2BS_RESP 1
138 #define CR_BS2MS_CMD 1
139 #define CR_BS2MS_RESP 0
141 /* Set T200 to 1 Second (OpenBTS uses 900ms) */
144 /* k value for each SAPI */
145 static uint8_t k_sapi[] = {1, 1, 1, 1, 1, 1, 1, 1};
155 static void lapdm_t200_cb(void *data);
156 static int rslms_send_i(struct lapdm_msg_ctx *mctx, int line);
158 /* UTILITY FUNCTIONS */
160 static inline uint8_t inc_mod8(uint8_t x)
165 static inline uint8_t add_mod8(uint8_t x, uint8_t y)
170 static inline uint8_t sub_mod8(uint8_t x, uint8_t y)
172 return (x - y) & 7; /* handle negative results correctly */
175 static void lapdm_dl_init(struct lapdm_datalink *dl,
176 struct lapdm_entity *entity)
178 memset(dl, 0, sizeof(*dl));
179 INIT_LLIST_HEAD(&dl->send_queue);
180 INIT_LLIST_HEAD(&dl->tx_queue);
181 dl->state = LAPDm_STATE_IDLE;
183 dl->t200.cb = &lapdm_t200_cb;
187 void lapdm_entity_init(struct lapdm_entity *le, enum lapdm_mode mode)
191 for (i = 0; i < ARRAY_SIZE(le->datalink); i++)
192 lapdm_dl_init(&le->datalink[i], le);
194 lapdm_entity_set_mode(le, mode);
197 void lapdm_channel_init(struct lapdm_channel *lc, enum lapdm_mode mode)
199 lapdm_entity_init(&lc->lapdm_acch, mode);
200 lapdm_entity_init(&lc->lapdm_dcch, mode);
204 static void lapdm_dl_flush_send(struct lapdm_datalink *dl)
208 /* Flush send-queue */
209 while ((msg = msgb_dequeue(&dl->send_queue)))
212 /* Clear send-buffer */
213 if (dl->send_buffer) {
214 msgb_free(dl->send_buffer);
215 dl->send_buffer = NULL;
219 static void lapdm_dl_flush_tx(struct lapdm_datalink *dl)
224 while ((msg = msgb_dequeue(&dl->tx_queue)))
226 for (i = 0; i < 8; i++)
227 dl->tx_length[i] = 0;
230 void lapdm_entity_exit(struct lapdm_entity *le)
233 struct lapdm_datalink *dl;
235 for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
236 dl = &le->datalink[i];
237 lapdm_dl_flush_tx(dl);
238 lapdm_dl_flush_send(dl);
240 msgb_free(dl->rcv_buffer);
244 void lapdm_channel_exit(struct lapdm_channel *lc)
246 lapdm_entity_exit(&lc->lapdm_acch);
247 lapdm_entity_exit(&lc->lapdm_dcch);
250 static void lapdm_dl_newstate(struct lapdm_datalink *dl, uint32_t state)
252 LOGP(DLLAPDM, LOGL_INFO, "new state %s -> %s\n",
253 lapdm_state_names[dl->state], lapdm_state_names[state]);
258 static struct lapdm_datalink *datalink_for_sapi(struct lapdm_entity *le, uint8_t sapi)
261 case LAPDm_SAPI_NORMAL:
262 return &le->datalink[0];
264 return &le->datalink[1];
270 /* remove the L2 header from a MSGB */
271 static inline unsigned char *msgb_pull_l2h(struct msgb *msg)
273 unsigned char *ret = msgb_pull(msg, msg->l3h - msg->l2h);
278 /* Append padding (if required) */
279 static void lapdm_pad_msgb(struct msgb *msg, uint8_t n201)
281 int pad_len = n201 - msgb_l2len(msg);
285 LOGP(DLLAPDM, LOGL_ERROR,
286 "cannot pad message that is already too big!\n");
290 data = msgb_put(msg, pad_len);
291 memset(data, 0x2B, pad_len);
294 /* input function that L2 calls when sending messages up to L3 */
295 static int rslms_sendmsg(struct msgb *msg, struct lapdm_entity *le)
302 /* call the layer2 message handler that is registered */
303 return le->l3_cb(msg, le, le->l3_ctx);
306 /* write a frame into the tx queue */
307 static int tx_ph_data_enqueue(struct lapdm_datalink *dl, struct msgb *msg,
308 uint8_t chan_nr, uint8_t link_id, uint8_t n201)
310 struct lapdm_entity *le = dl->entity;
311 struct osmo_phsap_prim pp;
313 /* if there is a pending message, queue it */
314 if (le->tx_pending || le->flags & LAPDM_ENT_F_POLLING_ONLY) {
315 *msgb_push(msg, 1) = n201;
316 *msgb_push(msg, 1) = link_id;
317 *msgb_push(msg, 1) = chan_nr;
318 msgb_enqueue(&dl->tx_queue, msg);
322 osmo_prim_init(&pp.oph, SAP_GSM_PH, PRIM_PH_DATA,
323 PRIM_OP_REQUEST, msg);
324 pp.u.data.chan_nr = chan_nr;
325 pp.u.data.link_id = link_id;
327 /* send the frame now */
328 le->tx_pending = 0; /* disabled flow control */
329 lapdm_pad_msgb(msg, n201);
331 return le->l1_prim_cb(&pp.oph, le->l1_ctx);
334 static struct msgb *tx_dequeue_msgb(struct lapdm_entity *le)
336 struct lapdm_datalink *dl;
337 int last = le->last_tx_dequeue;
338 int i = last, n = ARRAY_SIZE(le->datalink);
339 struct msgb *msg = NULL;
341 /* round-robin dequeue */
345 dl = &le->datalink[i];
346 if ((msg = msgb_dequeue(&dl->tx_queue)))
351 /* Set last dequeue position */
352 le->last_tx_dequeue = i;
358 /* dequeue a msg that's pending transmission via L1 and wrap it into
359 * a osmo_phsap_prim */
360 int lapdm_phsap_dequeue_prim(struct lapdm_entity *le, struct osmo_phsap_prim *pp)
365 msg = tx_dequeue_msgb(le);
369 /* if we have a message, send PH-DATA.req */
370 osmo_prim_init(&pp->oph, SAP_GSM_PH, PRIM_PH_DATA,
371 PRIM_OP_REQUEST, msg);
373 /* Pull chan_nr and link_id */
374 pp->u.data.chan_nr = *msg->data;
376 pp->u.data.link_id = *msg->data;
381 /* Pad the frame, we can transmit now */
382 lapdm_pad_msgb(msg, n201);
387 /* get next frame from the tx queue. because the ms has multiple datalinks,
388 * each datalink's queue is read round-robin.
390 static int l2_ph_data_conf(struct msgb *msg, struct lapdm_entity *le)
392 struct osmo_phsap_prim pp;
394 /* we may send again */
397 /* free confirm message */
401 if (lapdm_phsap_dequeue_prim(le, &pp) < 0) {
402 /* no message in all queues */
404 /* If user didn't request PH-EMPTY_FRAME.req, abort */
405 if (!(le->flags & LAPDM_ENT_F_EMPTY_FRAME))
408 /* otherwise, send PH-EMPTY_FRAME.req */
409 osmo_prim_init(&pp.oph, SAP_GSM_PH,
411 PRIM_OP_REQUEST, NULL);
416 return le->l1_prim_cb(&pp.oph, le->l1_ctx);
419 /* Create RSLms various RSLms messages */
420 static int send_rslms_rll_l3(uint8_t msg_type, struct lapdm_msg_ctx *mctx,
423 /* Add the RSL + RLL header */
424 rsl_rll_push_l3(msg, msg_type, mctx->chan_nr, mctx->link_id, 1);
426 /* send off the RSLms message to L3 */
427 return rslms_sendmsg(msg, mctx->dl->entity);
430 /* Take a B4 format message from L1 and create RSLms UNIT DATA IND */
431 static int send_rslms_rll_l3_ui(struct lapdm_msg_ctx *mctx, struct msgb *msg)
433 uint8_t l3_len = msg->tail - (uint8_t *)msgb_l3(msg);
434 struct abis_rsl_rll_hdr *rllh;
436 /* Add the RSL + RLL header */
437 msgb_tv16_push(msg, RSL_IE_L3_INFO, l3_len);
438 msgb_push(msg, 2 + 2);
439 rsl_rll_push_hdr(msg, RSL_MT_UNIT_DATA_IND, mctx->chan_nr,
441 rllh = (struct abis_rsl_rll_hdr *)msgb_l2(msg);
443 rllh->data[0] = RSL_IE_TIMING_ADVANCE;
444 rllh->data[1] = mctx->ta_ind;
446 rllh->data[2] = RSL_IE_MS_POWER;
447 rllh->data[3] = mctx->tx_power_ind;
449 return rslms_sendmsg(msg, mctx->dl->entity);
452 static int send_rll_simple(uint8_t msg_type, struct lapdm_msg_ctx *mctx)
456 msg = rsl_rll_simple(msg_type, mctx->chan_nr, mctx->link_id, 1);
458 /* send off the RSLms message to L3 */
459 return rslms_sendmsg(msg, mctx->dl->entity);
462 static int rsl_rll_error(uint8_t cause, struct lapdm_msg_ctx *mctx)
466 LOGP(DLLAPDM, LOGL_NOTICE, "sending MDL-ERROR-IND %d\n", cause);
467 msg = rsl_rll_simple(RSL_MT_ERROR_IND, mctx->chan_nr, mctx->link_id, 1);
468 msg->l2h = msgb_put(msg, sizeof(struct abis_rsl_rll_hdr));
469 msgb_tlv_put(msg, RSL_IE_RLM_CAUSE, 1, &cause);
470 return rslms_sendmsg(msg, mctx->dl->entity);
473 static int check_length_ind(struct lapdm_msg_ctx *mctx, uint8_t length_ind)
475 if (!(length_ind & 0x01)) {
476 /* G.4.1 If the EL bit is set to "0", an MDL-ERROR-INDICATION
477 * primitive with cause "frame not implemented" is sent to the
478 * mobile management entity. */
479 LOGP(DLLAPDM, LOGL_NOTICE,
480 "we don't support multi-octet length\n");
481 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
487 static int lapdm_send_resend(struct lapdm_datalink *dl)
489 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm resend");
492 /* Resend SABM/DISC from tx_hist */
493 length = dl->tx_length[0];
494 msg->l2h = msgb_put(msg, length);
495 memcpy(msg->l2h, dl->tx_hist[dl->V_send], length);
497 return tx_ph_data_enqueue(dl, msg, dl->mctx.chan_nr, dl->mctx.link_id,
501 static int lapdm_send_ua(struct lapdm_msg_ctx *mctx, uint8_t len, uint8_t *data)
503 uint8_t sapi = mctx->link_id & 7;
504 uint8_t f_bit = LAPDm_CTRL_PF_BIT(mctx->ctrl);
505 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm UA");
506 struct lapdm_entity *le = mctx->dl->entity;
508 msg->l2h = msgb_put(msg, 3 + len);
509 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
510 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_UA, f_bit);
511 msg->l2h[2] = LAPDm_LEN(len);
513 memcpy(msg->l2h + 3, data, len);
515 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
519 static int lapdm_send_dm(struct lapdm_msg_ctx *mctx)
521 uint8_t sapi = mctx->link_id & 7;
522 uint8_t f_bit = LAPDm_CTRL_PF_BIT(mctx->ctrl);
523 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm DM");
524 struct lapdm_entity *le = mctx->dl->entity;
526 msg->l2h = msgb_put(msg, 3);
527 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
528 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_DM, f_bit);
531 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
535 static int lapdm_send_rr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
537 uint8_t sapi = mctx->link_id & 7;
538 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RR");
539 struct lapdm_entity *le = mctx->dl->entity;
541 msg->l2h = msgb_put(msg, 3);
542 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
543 msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RR, f_bit);
544 msg->l2h[2] = LAPDm_LEN(0);
546 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
550 static int lapdm_send_rnr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
552 uint8_t sapi = mctx->link_id & 7;
553 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RNR");
554 struct lapdm_entity *le = mctx->dl->entity;
556 msg->l2h = msgb_put(msg, 3);
557 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
558 msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RNR, f_bit);
559 msg->l2h[2] = LAPDm_LEN(0);
561 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
565 static int lapdm_send_rej(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
567 uint8_t sapi = mctx->link_id & 7;
568 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm REJ");
569 struct lapdm_entity *le = mctx->dl->entity;
571 msg->l2h = msgb_put(msg, 3);
572 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
573 msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_REJ, f_bit);
574 msg->l2h[2] = LAPDm_LEN(0);
576 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
580 /* Timer callback on T200 expiry */
581 static void lapdm_t200_cb(void *data)
583 struct lapdm_datalink *dl = data;
585 LOGP(DLLAPDM, LOGL_INFO, "lapdm_t200_cb(%p) state=%u\n", dl, dl->state);
588 case LAPDm_STATE_SABM_SENT:
590 if (dl->retrans_ctr + 1 >= N200_EST_REL + 1) {
591 /* send RELEASE INDICATION to L3 */
592 send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
593 /* send MDL ERROR INIDCATION to L3 */
594 rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
595 /* flush tx buffers */
596 lapdm_dl_flush_tx(dl);
597 lapdm_dl_flush_send(dl);
598 /* go back to idle state */
599 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
600 /* NOTE: we must not change any other states or buffers
601 * and queues, since we may reconnect after handover
602 * failure. the buffered messages is replaced there */
605 /* retransmit SABM command */
606 lapdm_send_resend(dl);
607 /* increment re-transmission counter */
609 /* restart T200 (PH-READY-TO-SEND) */
610 osmo_timer_schedule(&dl->t200, T200);
612 case LAPDm_STATE_DISC_SENT:
614 if (dl->retrans_ctr + 1 >= N200_EST_REL + 1) {
615 /* send RELEASE INDICATION to L3 */
616 send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
617 /* send MDL ERROR INIDCATION to L3 */
618 rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
620 lapdm_dl_flush_tx(dl);
621 lapdm_dl_flush_send(dl);
622 /* go back to idle state */
623 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
624 /* NOTE: we must not change any other states or buffers
625 * and queues, since we may reconnect after handover
626 * failure. the buffered messages is replaced there */
629 /* retransmit DISC command */
630 lapdm_send_resend(dl);
631 /* increment re-transmission counter */
633 /* restart T200 (PH-READY-TO-SEND) */
634 osmo_timer_schedule(&dl->t200, T200);
636 case LAPDm_STATE_MF_EST:
639 lapdm_dl_newstate(dl, LAPDm_STATE_TIMER_RECOV);
641 case LAPDm_STATE_TIMER_RECOV:
643 if (dl->retrans_ctr < N200) {
644 /* retransmit I frame (V_s-1) with P=1, if any */
645 if (dl->tx_length[sub_mod8(dl->V_send, 1)]) {
649 LOGP(DLLAPDM, LOGL_INFO, "retransmit last frame "
650 "V(S)=%d\n", sub_mod8(dl->V_send, 1));
651 /* Create I frame (segment) from tx_hist */
652 length = dl->tx_length[sub_mod8(dl->V_send, 1)];
653 msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
654 msg->l2h = msgb_put(msg, length);
656 dl->tx_hist[sub_mod8(dl->V_send, 1)],
658 msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv,
659 sub_mod8(dl->V_send, 1), 1); /* P=1 */
660 tx_ph_data_enqueue(dl, msg, dl->mctx.chan_nr,
661 dl->mctx.link_id, dl->mctx.n201);
663 /* OR send appropriate supervision frame with P=1 */
664 if (!dl->own_busy && !dl->seq_err_cond) {
665 lapdm_send_rr(&dl->mctx, 1);
666 /* NOTE: In case of sequence error
667 * condition, the REJ frame has been
668 * transmitted when entering the
669 * condition, so it has not be done
672 } else if (dl->own_busy) {
673 lapdm_send_rnr(&dl->mctx, 1);
675 LOGP(DLLAPDM, LOGL_INFO, "unhandled, "
679 /* restart T200 (PH-READY-TO-SEND) */
680 osmo_timer_schedule(&dl->t200, T200);
682 /* send MDL ERROR INIDCATION to L3 */
683 rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
687 LOGP(DLLAPDM, LOGL_INFO, "T200 expired in unexpected "
688 "dl->state %u\n", dl->state);
692 /* 5.5.3.1: Common function to acknowlege frames up to the given N(R) value */
693 static void lapdm_acknowledge(struct lapdm_msg_ctx *mctx)
695 struct lapdm_datalink *dl = mctx->dl;
696 uint8_t nr = LAPDm_CTRL_Nr(mctx->ctrl);
697 int s = 0, rej = 0, t200_reset = 0;
700 /* supervisory frame ? */
701 if (LAPDm_CTRL_is_S(mctx->ctrl))
704 if (s && LAPDm_CTRL_S_BITS(mctx->ctrl) == LAPDm_S_REJ)
707 /* Flush all transmit buffers of acknowledged frames */
708 for (i = dl->V_ack; i != nr; i = inc_mod8(i)) {
709 if (dl->tx_length[i]) {
710 dl->tx_length[i] = 0;
711 LOGP(DLLAPDM, LOGL_INFO, "ack frame %d\n", i);
715 if (dl->state != LAPDm_STATE_TIMER_RECOV) {
716 /* When not in the timer recovery condition, the data
717 * link layer entity shall reset the timer T200 on
718 * receipt of a valid I frame with N(R) higher than V(A),
719 * or an REJ with an N(R) equal to V(A). */
720 if ((!rej && nr != dl->V_ack)
721 || (rej && nr == dl->V_ack)) {
722 LOGP(DLLAPDM, LOGL_INFO, "reset t200\n");
724 osmo_timer_del(&dl->t200);
725 /* 5.5.3.1 Note 1 + 2 imply timer recovery cond. */
727 /* 5.7.4: N(R) sequence error
728 * N(R) is called valid, if and only if
729 * (N(R)-V(A)) mod 8 <= (V(S)-V(A)) mod 8.
731 if (sub_mod8(nr, dl->V_ack) > sub_mod8(dl->V_send, dl->V_ack)) {
732 LOGP(DLLAPDM, LOGL_NOTICE, "N(R) sequence error\n");
733 rsl_rll_error(RLL_CAUSE_SEQ_ERR, mctx);
737 /* V(A) shall be set to the value of N(R) */
740 /* If T200 has been reset by the receipt of an I, RR or RNR frame,
741 * and if there are outstanding I frames, restart T200 */
742 if (t200_reset && !rej) {
743 if (dl->tx_length[dl->V_send - 1]) {
744 LOGP(DLLAPDM, LOGL_INFO, "start T200, due to unacked I "
746 osmo_timer_schedule(&dl->t200, T200);
753 /* Receive a LAPDm U (Unnumbered) message from L1 */
754 static int lapdm_rx_u(struct msgb *msg, struct lapdm_msg_ctx *mctx)
756 struct lapdm_datalink *dl = mctx->dl;
757 struct lapdm_entity *le = dl->entity;
762 switch (LAPDm_CTRL_U_BITS(mctx->ctrl)) {
764 rsl_msg = RSL_MT_EST_IND;
766 LOGP(DLLAPDM, LOGL_INFO, "SABM received\n");
768 dl->seq_err_cond = 0;
769 /* G.2.2 Wrong value of the C/R bit */
770 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
771 LOGP(DLLAPDM, LOGL_NOTICE, "SABM response error\n");
773 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
777 length = msg->l2h[2] >> 2;
778 /* G.4.5 If SABM is received with L>N201 or with M bit
779 * set, AN MDL-ERROR-INDICATION is sent to MM.
781 if ((msg->l2h[2] & LAPDm_MORE) || length + 3 > mctx->n201) {
782 LOGP(DLLAPDM, LOGL_NOTICE, "SABM too large error\n");
784 rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
788 /* Must be Format B */
789 rc = check_length_ind(mctx, msg->l2h[2]);
795 case LAPDm_STATE_IDLE:
796 /* Set chan_nr and link_id for established connection */
797 memset(&dl->mctx, 0, sizeof(dl->mctx));
799 dl->mctx.chan_nr = mctx->chan_nr;
800 dl->mctx.link_id = mctx->link_id;
801 dl->mctx.n201 = mctx->n201;
803 case LAPDm_STATE_MF_EST:
805 rsl_msg = RSL_MT_EST_CONF;
808 LOGP(DLLAPDM, LOGL_INFO, "SABM command, multiple "
809 "frame established state\n");
810 /* check for contention resoultion */
811 if (dl->tx_hist[0][2] >> 2) {
812 LOGP(DLLAPDM, LOGL_NOTICE, "SABM not allowed "
813 "during contention resolution\n");
814 rsl_rll_error(RLL_CAUSE_SABM_INFO_NOTALL, mctx);
818 case LAPDm_STATE_DISC_SENT:
819 /* 5.4.6.2 send DM with F=P */
821 /* reset Timer T200 */
822 osmo_timer_del(&dl->t200);
824 return send_rll_simple(RSL_MT_REL_CONF, mctx);
826 lapdm_send_ua(mctx, length, msg->l2h + 3);
830 /* send UA response */
831 lapdm_send_ua(mctx, length, msg->l2h + 3);
832 /* set Vs, Vr and Va to 0 */
833 dl->V_send = dl->V_recv = dl->V_ack = 0;
835 dl->tx_length[0] = 0;
836 /* enter multiple-frame-established state */
837 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
838 /* send notification to L3 */
840 /* 5.4.1.2 Normal establishment procedures */
841 rc = send_rll_simple(rsl_msg, mctx);
844 /* 5.4.1.4 Contention resolution establishment */
845 msg->l3h = msg->l2h + 3;
847 rc = send_rslms_rll_l3(rsl_msg, mctx, msg);
851 LOGP(DLLAPDM, LOGL_INFO, "DM received\n");
852 /* G.2.2 Wrong value of the C/R bit */
853 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd) {
854 LOGP(DLLAPDM, LOGL_NOTICE, "DM command error\n");
856 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
859 if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
860 /* 5.4.1.2 DM responses with the F bit set to "0"
867 case LAPDm_STATE_SABM_SENT:
869 case LAPDm_STATE_MF_EST:
870 if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 1) {
871 LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM "
873 rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP, mctx);
875 LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM "
876 "response, multiple frame established "
878 rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP_MF, mctx);
882 case LAPDm_STATE_TIMER_RECOV:
883 /* DM is normal in case PF = 1 */
884 if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 0) {
885 LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM "
886 "response, multiple frame established "
888 rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP_MF, mctx);
893 case LAPDm_STATE_DISC_SENT:
894 /* reset Timer T200 */
895 osmo_timer_del(&dl->t200);
896 /* go to idle state */
897 lapdm_dl_flush_tx(dl);
898 lapdm_dl_flush_send(dl);
899 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
900 rc = send_rll_simple(RSL_MT_REL_CONF, mctx);
903 case LAPDm_STATE_IDLE:
904 /* 5.4.5 all other frame types shall be discarded */
906 LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM response! "
912 osmo_timer_del(&dl->t200);
913 rc = send_rll_simple(RSL_MT_REL_IND, mctx);
917 LOGP(DLLAPDM, LOGL_INFO, "UI received\n");
918 /* G.2.2 Wrong value of the C/R bit */
919 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
920 LOGP(DLLAPDM, LOGL_NOTICE, "UI indicates response "
923 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
927 length = msg->l2h[2] >> 2;
928 /* FIXME: G.4.5 If UI is received with L>N201 or with M bit
929 * set, AN MDL-ERROR-INDICATION is sent to MM.
932 if (mctx->lapdm_fmt == LAPDm_FMT_B4) {
934 msg->l3h = msg->l2h + 2;
936 rc = check_length_ind(mctx, msg->l2h[2]);
941 length = msg->l2h[2] >> 2;
942 msg->l3h = msg->l2h + 3;
944 /* do some length checks */
946 /* 5.3.3 UI frames received with the length indicator
947 * set to "0" shall be ignored
949 LOGP(DLLAPDM, LOGL_INFO, "length=0 (discarding)\n");
953 switch (LAPDm_ADDR_SAPI(mctx->addr)) {
954 case LAPDm_SAPI_NORMAL:
958 /* 5.3.3 UI frames with invalid SAPI values shall be
961 LOGP(DLLAPDM, LOGL_INFO, "sapi=%u (discarding)\n",
962 LAPDm_ADDR_SAPI(mctx->addr));
967 rc = send_rslms_rll_l3_ui(mctx, msg);
970 rsl_msg = RSL_MT_REL_IND;
972 LOGP(DLLAPDM, LOGL_INFO, "DISC received\n");
974 lapdm_dl_flush_tx(dl);
975 lapdm_dl_flush_send(dl);
977 dl->seq_err_cond = 0;
978 /* G.2.2 Wrong value of the C/R bit */
979 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
980 LOGP(DLLAPDM, LOGL_NOTICE, "DISC response error\n");
982 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
985 length = msg->l2h[2] >> 2;
986 if (length > 0 || msg->l2h[2] & 0x02) {
987 /* G.4.4 If a DISC or DM frame is received with L>0 or
988 * with the M bit set to "1", an MDL-ERROR-INDICATION
989 * primitive with cause "U frame with incorrect
990 * parameters" is sent to the mobile management entity.
992 LOGP(DLLAPDM, LOGL_NOTICE,
993 "U frame iwth incorrect parameters ");
995 rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
999 case LAPDm_STATE_IDLE:
1000 LOGP(DLLAPDM, LOGL_INFO, "DISC in idle state\n");
1001 /* send DM with F=P */
1003 return lapdm_send_dm(mctx);
1004 case LAPDm_STATE_SABM_SENT:
1005 LOGP(DLLAPDM, LOGL_INFO, "DISC in SABM state\n");
1006 /* 5.4.6.2 send DM with F=P */
1007 lapdm_send_dm(mctx);
1008 /* reset Timer T200 */
1009 osmo_timer_del(&dl->t200);
1011 return send_rll_simple(RSL_MT_REL_IND, mctx);
1012 case LAPDm_STATE_MF_EST:
1013 case LAPDm_STATE_TIMER_RECOV:
1014 LOGP(DLLAPDM, LOGL_INFO, "DISC in est state\n");
1016 case LAPDm_STATE_DISC_SENT:
1017 LOGP(DLLAPDM, LOGL_INFO, "DISC in disc state\n");
1018 rsl_msg = RSL_MT_REL_CONF;
1021 lapdm_send_ua(mctx, length, msg->l2h + 3);
1025 /* send UA response */
1026 lapdm_send_ua(mctx, length, msg->l2h + 3);
1027 /* reset Timer T200 */
1028 osmo_timer_del(&dl->t200);
1029 /* enter idle state */
1030 lapdm_dl_flush_tx(dl);
1031 lapdm_dl_flush_send(dl);
1032 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1033 /* send notification to L3 */
1034 rc = send_rll_simple(rsl_msg, mctx);
1038 LOGP(DLLAPDM, LOGL_INFO, "UA received\n");
1039 /* G.2.2 Wrong value of the C/R bit */
1040 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd) {
1041 LOGP(DLLAPDM, LOGL_NOTICE, "UA indicates command "
1044 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1048 length = msg->l2h[2] >> 2;
1049 /* G.4.5 If UA is received with L>N201 or with M bit
1050 * set, AN MDL-ERROR-INDICATION is sent to MM.
1052 if ((msg->l2h[2] & LAPDm_MORE) || length + 3 > mctx->n201) {
1053 LOGP(DLLAPDM, LOGL_NOTICE, "UA too large error\n");
1055 rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
1059 if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1060 /* 5.4.1.2 A UA response with the F bit set to "0"
1063 LOGP(DLLAPDM, LOGL_INFO, "F=0 (discarding)\n");
1067 switch (dl->state) {
1068 case LAPDm_STATE_SABM_SENT:
1070 case LAPDm_STATE_MF_EST:
1071 case LAPDm_STATE_TIMER_RECOV:
1072 LOGP(DLLAPDM, LOGL_INFO, "unsolicited UA response! "
1074 rsl_rll_error(RLL_CAUSE_UNSOL_UA_RESP, mctx);
1077 case LAPDm_STATE_DISC_SENT:
1078 LOGP(DLLAPDM, LOGL_INFO, "UA in disconnect state\n");
1079 /* reset Timer T200 */
1080 osmo_timer_del(&dl->t200);
1081 /* go to idle state */
1082 lapdm_dl_flush_tx(dl);
1083 lapdm_dl_flush_send(dl);
1084 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1085 rc = send_rll_simple(RSL_MT_REL_CONF, mctx);
1088 case LAPDm_STATE_IDLE:
1089 /* 5.4.5 all other frame types shall be discarded */
1091 LOGP(DLLAPDM, LOGL_INFO, "unsolicited UA response! "
1096 LOGP(DLLAPDM, LOGL_INFO, "UA in SABM state\n");
1097 /* reset Timer T200 */
1098 osmo_timer_del(&dl->t200);
1099 /* compare UA with SABME if contention resolution is applied */
1100 if (dl->tx_hist[0][2] >> 2) {
1101 rc = check_length_ind(mctx, msg->l2h[2]);
1103 rc = send_rll_simple(RSL_MT_REL_IND, mctx);
1105 /* go to idle state */
1106 lapdm_dl_flush_tx(dl);
1107 lapdm_dl_flush_send(dl);
1108 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1111 length = msg->l2h[2] >> 2;
1112 if (length != (dl->tx_hist[0][2] >> 2)
1113 || !!memcmp(dl->tx_hist[0] + 3, msg->l2h + 3,
1115 LOGP(DLLAPDM, LOGL_INFO, "**** UA response "
1116 "mismatches ****\n");
1117 rc = send_rll_simple(RSL_MT_REL_IND, mctx);
1119 /* go to idle state */
1120 lapdm_dl_flush_tx(dl);
1121 lapdm_dl_flush_send(dl);
1122 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1126 /* set Vs, Vr and Va to 0 */
1127 dl->V_send = dl->V_recv = dl->V_ack = 0;
1129 dl->tx_length[0] = 0;
1130 /* enter multiple-frame-established state */
1131 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1132 /* send outstanding frames, if any (resume / reconnect) */
1133 rslms_send_i(mctx, __LINE__);
1134 /* send notification to L3 */
1135 rc = send_rll_simple(RSL_MT_EST_CONF, mctx);
1140 LOGP(DLLAPDM, LOGL_NOTICE, "Unnumbered frame not allowed.\n");
1142 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1148 /* Receive a LAPDm S (Supervisory) message from L1 */
1149 static int lapdm_rx_s(struct msgb *msg, struct lapdm_msg_ctx *mctx)
1151 struct lapdm_datalink *dl = mctx->dl;
1152 struct lapdm_entity *le = dl->entity;
1155 length = msg->l2h[2] >> 2;
1156 if (length > 0 || msg->l2h[2] & 0x02) {
1157 /* G.4.3 If a supervisory frame is received with L>0 or
1158 * with the M bit set to "1", an MDL-ERROR-INDICATION
1159 * primitive with cause "S frame with incorrect
1160 * parameters" is sent to the mobile management entity. */
1161 LOGP(DLLAPDM, LOGL_NOTICE,
1162 "S frame with incorrect parameters\n");
1164 rsl_rll_error(RLL_CAUSE_SFRM_INC_PARAM, mctx);
1168 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
1169 && LAPDm_CTRL_PF_BIT(mctx->ctrl)
1170 && dl->state != LAPDm_STATE_TIMER_RECOV) {
1171 /* 5.4.2.2: Inidcate error on supervisory reponse F=1 */
1172 LOGP(DLLAPDM, LOGL_NOTICE, "S frame response with F=1 error\n");
1173 rsl_rll_error(RLL_CAUSE_UNSOL_SPRV_RESP, mctx);
1176 switch (dl->state) {
1177 case LAPDm_STATE_IDLE:
1178 /* if P=1, respond DM with F=1 (5.2.2) */
1179 /* 5.4.5 all other frame types shall be discarded */
1180 if (LAPDm_CTRL_PF_BIT(mctx->ctrl))
1181 lapdm_send_dm(mctx); /* F=P */
1183 case LAPDm_STATE_SABM_SENT:
1184 case LAPDm_STATE_DISC_SENT:
1185 LOGP(DLLAPDM, LOGL_NOTICE, "S frame ignored in this state\n");
1189 switch (LAPDm_CTRL_S_BITS(mctx->ctrl)) {
1191 LOGP(DLLAPDM, LOGL_INFO, "RR received\n");
1192 /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
1193 lapdm_acknowledge(mctx);
1196 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd
1197 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1198 if (!dl->own_busy && !dl->seq_err_cond) {
1199 LOGP(DLLAPDM, LOGL_NOTICE, "RR frame command "
1200 "with polling bit set and we are not "
1201 "busy, so we reply with RR frame\n");
1202 lapdm_send_rr(mctx, 1);
1203 /* NOTE: In case of sequence error condition,
1204 * the REJ frame has been transmitted when
1205 * entering the condition, so it has not be
1208 } else if (dl->own_busy) {
1209 LOGP(DLLAPDM, LOGL_NOTICE, "RR frame command "
1210 "with polling bit set and we are busy, "
1211 "so we reply with RR frame\n");
1212 lapdm_send_rnr(mctx, 1);
1214 } else if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
1215 && LAPDm_CTRL_PF_BIT(mctx->ctrl)
1216 && dl->state == LAPDm_STATE_TIMER_RECOV) {
1217 LOGP(DLLAPDM, LOGL_INFO, "RR response with F==1, "
1218 "and we are in timer recovery state, so "
1219 "we leave that state\n");
1220 /* V(S) to the N(R) in the RR frame */
1221 dl->V_send = LAPDm_CTRL_Nr(mctx->ctrl);
1222 /* reset Timer T200 */
1223 osmo_timer_del(&dl->t200);
1224 /* 5.5.7 Clear timer recovery condition */
1225 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1227 /* Send message, if possible due to acknowledged data */
1228 rslms_send_i(mctx, __LINE__);
1232 LOGP(DLLAPDM, LOGL_INFO, "RNR received\n");
1233 /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
1234 lapdm_acknowledge(mctx);
1237 /* Set peer receiver busy condition */
1240 if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1241 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd) {
1242 if (!dl->own_busy) {
1243 LOGP(DLLAPDM, LOGL_INFO, "RNR poll "
1244 "command and we are not busy, "
1245 "so we reply with RR final "
1247 /* Send RR with F=1 */
1248 lapdm_send_rr(mctx, 1);
1250 LOGP(DLLAPDM, LOGL_INFO, "RNR poll "
1251 "command and we are busy, so "
1252 "we reply with RNR final "
1254 /* Send RNR with F=1 */
1255 lapdm_send_rnr(mctx, 1);
1257 } else if (dl->state == LAPDm_STATE_TIMER_RECOV) {
1258 LOGP(DLLAPDM, LOGL_INFO, "RNR poll response "
1259 "and we in timer recovery state, so "
1260 "we leave that state\n");
1261 /* 5.5.7 Clear timer recovery condition */
1262 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1263 /* V(S) to the N(R) in the RNR frame */
1264 dl->V_send = LAPDm_CTRL_Nr(mctx->ctrl);
1267 LOGP(DLLAPDM, LOGL_INFO, "RNR not polling/final state "
1270 /* Send message, if possible due to acknowledged data */
1271 rslms_send_i(mctx, __LINE__);
1275 LOGP(DLLAPDM, LOGL_INFO, "REJ received\n");
1276 /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
1277 lapdm_acknowledge(mctx);
1280 if (dl->state != LAPDm_STATE_TIMER_RECOV) {
1281 /* Clear an existing peer receiver busy condition */
1283 /* V(S) and V(A) to the N(R) in the REJ frame */
1284 dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
1285 /* reset Timer T200 */
1286 osmo_timer_del(&dl->t200);
1288 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd
1289 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1290 if (!dl->own_busy && !dl->seq_err_cond) {
1291 LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
1292 "command not in timer recovery "
1293 "state and not in own busy "
1294 "condition received, so we "
1295 "respond with RR final "
1297 lapdm_send_rr(mctx, 1);
1298 /* NOTE: In case of sequence error
1299 * condition, the REJ frame has been
1300 * transmitted when entering the
1301 * condition, so it has not be done
1304 } else if (dl->own_busy) {
1305 LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
1306 "command not in timer recovery "
1307 "state and in own busy "
1308 "condition received, so we "
1309 "respond with RNR final "
1311 lapdm_send_rnr(mctx, 1);
1314 LOGP(DLLAPDM, LOGL_INFO, "REJ response or not "
1315 "polling command not in timer recovery "
1316 "state received\n");
1317 /* send MDL ERROR INIDCATION to L3 */
1318 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
1319 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1320 rsl_rll_error(RLL_CAUSE_UNSOL_SPRV_RESP, mctx);
1323 } else if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
1324 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1325 LOGP(DLLAPDM, LOGL_INFO, "REJ poll response in timer "
1326 "recovery state received\n");
1327 /* Clear an existing peer receiver busy condition */
1329 /* 5.5.7 Clear timer recovery condition */
1330 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1331 /* V(S) and V(A) to the N(R) in the REJ frame */
1332 dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
1333 /* reset Timer T200 */
1334 osmo_timer_del(&dl->t200);
1336 /* Clear an existing peer receiver busy condition */
1338 /* V(S) and V(A) to the N(R) in the REJ frame */
1339 dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
1341 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd
1342 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1343 if (!dl->own_busy && !dl->seq_err_cond) {
1344 LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
1345 "command in timer recovery "
1346 "state and not in own busy "
1347 "condition received, so we "
1348 "respond with RR final "
1350 lapdm_send_rr(mctx, 1);
1351 /* NOTE: In case of sequence error
1352 * condition, the REJ frame has been
1353 * transmitted when entering the
1354 * condition, so it has not be done
1357 } else if (dl->own_busy) {
1358 LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
1359 "command in timer recovery "
1360 "state and in own busy "
1361 "condition received, so we "
1362 "respond with RNR final "
1364 lapdm_send_rnr(mctx, 1);
1367 LOGP(DLLAPDM, LOGL_INFO, "REJ response or not "
1368 "polling command in timer recovery "
1369 "state received\n");
1372 /* FIXME: 5.5.4.2 2) */
1374 /* Send message, if possible due to acknowledged data */
1375 rslms_send_i(mctx, __LINE__);
1380 LOGP(DLLAPDM, LOGL_NOTICE, "Supervisory frame not allowed.\n");
1382 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1389 /* Receive a LAPDm I (Information) message from L1 */
1390 static int lapdm_rx_i(struct msgb *msg, struct lapdm_msg_ctx *mctx)
1392 struct lapdm_datalink *dl = mctx->dl;
1393 struct lapdm_entity *le = dl->entity;
1394 //uint8_t nr = LAPDm_CTRL_Nr(mctx->ctrl);
1395 uint8_t ns = LAPDm_CTRL_I_Ns(mctx->ctrl);
1399 LOGP(DLLAPDM, LOGL_NOTICE, "I received\n");
1401 /* G.2.2 Wrong value of the C/R bit */
1402 if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
1403 LOGP(DLLAPDM, LOGL_NOTICE, "I frame response not allowed\n");
1405 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1409 length = msg->l2h[2] >> 2;
1410 if (length == 0 || length + 3 > mctx->n201) {
1411 /* G.4.2 If the length indicator of an I frame is set
1412 * to a numerical value L>N201 or L=0, an MDL-ERROR-INDICATION
1413 * primitive with cause "I frame with incorrect length"
1414 * is sent to the mobile management entity. */
1415 LOGP(DLLAPDM, LOGL_NOTICE, "I frame length not allowed\n");
1417 rsl_rll_error(RLL_CAUSE_IFRM_INC_LEN, mctx);
1421 /* G.4.2 If the numerical value of L is L<N201 and the M
1422 * bit is set to "1", then an MDL-ERROR-INDICATION primitive with
1423 * cause "I frame with incorrect use of M bit" is sent to the
1424 * mobile management entity. */
1425 if ((msg->l2h[2] & LAPDm_MORE) && length + 3 < mctx->n201) {
1426 LOGP(DLLAPDM, LOGL_NOTICE, "I frame with M bit too short\n");
1428 rsl_rll_error(RLL_CAUSE_IFRM_INC_MBITS, mctx);
1432 switch (dl->state) {
1433 case LAPDm_STATE_IDLE:
1434 /* if P=1, respond DM with F=1 (5.2.2) */
1435 /* 5.4.5 all other frame types shall be discarded */
1436 if (LAPDm_CTRL_PF_BIT(mctx->ctrl))
1437 lapdm_send_dm(mctx); /* F=P */
1439 case LAPDm_STATE_SABM_SENT:
1440 case LAPDm_STATE_DISC_SENT:
1441 LOGP(DLLAPDM, LOGL_NOTICE, "I frame ignored in this state\n");
1446 /* 5.7.1: N(s) sequence error */
1447 if (ns != dl->V_recv) {
1448 LOGP(DLLAPDM, LOGL_NOTICE, "N(S) sequence error: N(S)=%u, "
1449 "V(R)=%u\n", ns, dl->V_recv);
1452 if (!dl->seq_err_cond) {
1453 /* FIXME: help me understand what exactly todo here
1454 dl->seq_err_cond = 1;
1456 lapdm_send_rej(mctx, LAPDm_CTRL_PF_BIT(mctx->ctrl));
1461 dl->seq_err_cond = 0;
1463 /* Increment receiver state */
1464 dl->V_recv = inc_mod8(dl->V_recv);
1465 LOGP(DLLAPDM, LOGL_NOTICE, "incrementing V(R) to %u\n", dl->V_recv);
1467 /* 5.5.3.1: Acknowlege all transmitted frames up the the N(R)-1 */
1468 lapdm_acknowledge(mctx); /* V(A) is also set here */
1470 /* Only if we are not in own receiver busy condition */
1471 if (!dl->own_busy) {
1472 /* if the frame carries a complete segment */
1473 if (!(msg->l2h[2] & LAPDm_MORE)
1474 && !dl->rcv_buffer) {
1475 LOGP(DLLAPDM, LOGL_INFO, "message in single I frame\n");
1476 /* send a DATA INDICATION to L3 */
1477 msg->l3h = msg->l2h + 3;
1480 msg->tail = msg->data + length;
1481 rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx, msg);
1483 /* create rcv_buffer */
1484 if (!dl->rcv_buffer) {
1485 LOGP(DLLAPDM, LOGL_INFO, "message in multiple I "
1486 "frames (first message)\n");
1487 dl->rcv_buffer = msgb_alloc_headroom(200+56, 56,
1489 dl->rcv_buffer->l3h = dl->rcv_buffer->data;
1491 /* concat. rcv_buffer */
1492 if (msgb_l3len(dl->rcv_buffer) + length > 200) {
1493 LOGP(DLLAPDM, LOGL_NOTICE, "Received frame "
1496 memcpy(msgb_put(dl->rcv_buffer, length),
1497 msg->l2h + 3, length);
1499 /* if the last segment was received */
1500 if (!(msg->l2h[2] & LAPDm_MORE)) {
1501 LOGP(DLLAPDM, LOGL_INFO, "message in multiple I "
1502 "frames (last message)\n");
1503 rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx,
1505 dl->rcv_buffer = NULL;
1507 LOGP(DLLAPDM, LOGL_INFO, "message in multiple I "
1508 "frames (next message)\n");
1513 LOGP(DLLAPDM, LOGL_INFO, "I frame ignored during own receiver "
1514 "busy condition\n");
1516 /* Check for P bit */
1517 if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1519 /* check if we are not in own receiver busy */
1520 if (!dl->own_busy) {
1521 LOGP(DLLAPDM, LOGL_INFO, "we are not busy, send RR\n");
1522 /* Send RR with F=1 */
1523 rc = lapdm_send_rr(mctx, 1);
1525 LOGP(DLLAPDM, LOGL_INFO, "we are busy, send RNR\n");
1526 /* Send RNR with F=1 */
1527 rc = lapdm_send_rnr(mctx, 1);
1531 /* check if we are not in own receiver busy */
1532 if (!dl->own_busy) {
1533 /* NOTE: V(R) is already set above */
1534 rc = rslms_send_i(mctx, __LINE__);
1536 LOGP(DLLAPDM, LOGL_INFO, "we are not busy and "
1537 "have no pending data, send RR\n");
1538 /* Send RR with F=0 */
1539 return lapdm_send_rr(mctx, 0);
1541 /* all I or one RR is sent, we are done */
1544 LOGP(DLLAPDM, LOGL_INFO, "we are busy, send RNR\n");
1545 /* Send RNR with F=0 */
1546 rc = lapdm_send_rnr(mctx, 0);
1550 /* Send message, if possible due to acknowledged data */
1551 rslms_send_i(mctx, __LINE__);
1556 /* Receive a LAPDm message from L1 */
1557 static int lapdm_ph_data_ind(struct msgb *msg, struct lapdm_msg_ctx *mctx)
1561 /* G.2.3 EA bit set to "0" is not allowed in GSM */
1562 if (!LAPDm_ADDR_EA(mctx->addr)) {
1563 LOGP(DLLAPDM, LOGL_NOTICE, "EA bit 0 is not allowed in GSM\n");
1565 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1569 if (LAPDm_CTRL_is_U(mctx->ctrl))
1570 rc = lapdm_rx_u(msg, mctx);
1571 else if (LAPDm_CTRL_is_S(mctx->ctrl))
1572 rc = lapdm_rx_s(msg, mctx);
1573 else if (LAPDm_CTRL_is_I(mctx->ctrl))
1574 rc = lapdm_rx_i(msg, mctx);
1576 LOGP(DLLAPDM, LOGL_NOTICE, "unknown LAPDm format\n");
1583 /* input into layer2 (from layer 1) */
1584 static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, uint8_t chan_nr, uint8_t link_id)
1586 uint8_t cbits = chan_nr >> 3;
1587 uint8_t sapi; /* we cannot take SAPI from link_id, as L1 has no clue */
1588 struct lapdm_msg_ctx mctx;
1591 /* when we reach here, we have a msgb with l2h pointing to the raw
1592 * 23byte mac block. The l1h has already been purged. */
1594 mctx.chan_nr = chan_nr;
1595 mctx.link_id = link_id;
1596 mctx.addr = mctx.ctrl = 0;
1598 /* check for L1 chan_nr/link_id and determine LAPDm hdr format */
1599 if (cbits == 0x10 || cbits == 0x12) {
1600 /* Format Bbis is used on BCCH and CCCH(PCH, NCH and AGCH) */
1601 mctx.lapdm_fmt = LAPDm_FMT_Bbis;
1602 mctx.n201 = N201_Bbis;
1605 if (mctx.link_id & 0x40) {
1606 /* It was received from network on SACCH */
1608 /* If sent by BTS, lapdm_fmt must be B4 */
1609 if (le->mode == LAPDM_MODE_MS) {
1610 mctx.lapdm_fmt = LAPDm_FMT_B4;
1611 mctx.n201 = N201_B4;
1612 LOGP(DLLAPDM, LOGL_INFO, "fmt=B4\n");
1614 mctx.lapdm_fmt = LAPDm_FMT_B;
1615 mctx.n201 = N201_AB_SACCH;
1616 LOGP(DLLAPDM, LOGL_INFO, "fmt=B\n");
1618 /* SACCH frames have a two-byte L1 header that
1619 * OsmocomBB L1 doesn't strip */
1620 mctx.tx_power_ind = msg->l2h[0] & 0x1f;
1621 mctx.ta_ind = msg->l2h[1];
1624 sapi = (msg->l2h[0] >> 2) & 7;
1626 mctx.lapdm_fmt = LAPDm_FMT_B;
1627 LOGP(DLLAPDM, LOGL_INFO, "fmt=B\n");
1628 mctx.n201 = 23; // FIXME: select correct size by chan.
1629 sapi = (msg->l2h[0] >> 2) & 7;
1633 mctx.dl = datalink_for_sapi(le, sapi);
1634 /* G.2.1 No action on frames containing an unallocated SAPI. */
1636 LOGP(DLLAPDM, LOGL_NOTICE, "Received frame for unsupported "
1637 "SAPI %d!\n", sapi);
1643 switch (mctx.lapdm_fmt) {
1647 mctx.addr = msg->l2h[0];
1648 if (!(mctx.addr & 0x01)) {
1649 LOGP(DLLAPDM, LOGL_ERROR, "we don't support "
1650 "multibyte addresses (discarding)\n");
1654 mctx.ctrl = msg->l2h[1];
1655 /* obtain SAPI from address field */
1656 mctx.link_id |= LAPDm_ADDR_SAPI(mctx.addr);
1657 rc = lapdm_ph_data_ind(msg, &mctx);
1659 case LAPDm_FMT_Bter:
1663 case LAPDm_FMT_Bbis:
1664 /* directly pass up to layer3 */
1665 LOGP(DLLAPDM, LOGL_INFO, "fmt=Bbis UI\n");
1666 msg->l3h = msg->l2h;
1668 rc = send_rslms_rll_l3(RSL_MT_UNIT_DATA_IND, &mctx, msg);
1677 /* input into layer2 (from layer 1) */
1678 static int l2_ph_rach_ind(struct lapdm_entity *le, uint8_t ra, uint32_t fn, uint8_t acc_delay)
1680 struct abis_rsl_cchan_hdr *ch;
1681 struct gsm48_req_ref req_ref;
1683 struct msgb *msg = msgb_alloc_headroom(512, 64, "RSL CHAN RQD");
1685 msg->l2h = msgb_push(msg, sizeof(*ch));
1686 ch = (struct abis_rsl_cchan_hdr *)msg->l2h;
1687 rsl_init_cchan_hdr(ch, RSL_MT_CHAN_RQD);
1688 ch->chan_nr = RSL_CHAN_RACH;
1690 /* generate a RSL CHANNEL REQUIRED message */
1691 gsm_fn2gsmtime(>, fn);
1693 req_ref.t1 = gt.t1; /* FIXME: modulo? */
1695 req_ref.t3_low = gt.t3 & 7;
1696 req_ref.t3_high = gt.t3 >> 3;
1698 msgb_tv_fixed_put(msg, RSL_IE_REQ_REFERENCE, 3, (uint8_t *) &req_ref);
1699 msgb_tv_put(msg, RSL_IE_ACCESS_DELAY, acc_delay);
1701 return rslms_sendmsg(msg, le);
1704 static int l2_ph_chan_conf(struct msgb *msg, struct lapdm_entity *le, uint32_t frame_nr);
1706 int lapdm_phsap_up(struct osmo_prim_hdr *oph, struct lapdm_entity *le)
1708 struct osmo_phsap_prim *pp = (struct osmo_phsap_prim *) oph;
1711 if (oph->sap != SAP_GSM_PH) {
1712 LOGP(DLLAPDM, LOGL_ERROR, "primitive for unknown SAP %u\n",
1717 switch (oph->primitive) {
1719 if (oph->operation != PRIM_OP_INDICATION) {
1720 LOGP(DLLAPDM, LOGL_ERROR, "PH_DATA is not INDICATION %u\n",
1724 rc = l2_ph_data_ind(oph->msg, le, pp->u.data.chan_nr,
1725 pp->u.data.link_id);
1728 if (oph->operation != PRIM_OP_INDICATION) {
1729 LOGP(DLLAPDM, LOGL_ERROR, "PH_RTS is not INDICATION %u\n",
1733 rc = l2_ph_data_conf(oph->msg, le);
1736 switch (oph->operation) {
1737 case PRIM_OP_INDICATION:
1738 rc = l2_ph_rach_ind(le, pp->u.rach_ind.ra, pp->u.rach_ind.fn,
1739 pp->u.rach_ind.acc_delay);
1741 case PRIM_OP_CONFIRM:
1742 rc = l2_ph_chan_conf(oph->msg, le, pp->u.rach_ind.fn);
1754 /* L3 -> L2 / RSLMS -> LAPDm */
1756 /* L3 requests establishment of data link */
1757 static int rslms_rx_rll_est_req(struct msgb *msg, struct lapdm_datalink *dl)
1759 struct lapdm_entity *le = dl->entity;
1760 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1761 uint8_t chan_nr = rllh->chan_nr;
1762 uint8_t link_id = rllh->link_id;
1763 uint8_t sapi = rllh->link_id & 7;
1764 struct tlv_parsed tv;
1766 uint8_t n201 = 23; //FIXME
1768 /* Set chan_nr and link_id for established connection */
1769 memset(&dl->mctx, 0, sizeof(dl->mctx));
1771 dl->mctx.n201 = n201;
1772 dl->mctx.chan_nr = chan_nr;
1773 dl->mctx.link_id = link_id;
1775 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1776 if (TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
1777 msg->l3h = TLVP_VAL(&tv, RSL_IE_L3_INFO);
1778 /* contention resolution establishment procedure */
1780 /* According to clause 6, the contention resolution
1781 * procedure is only permitted with SAPI value 0 */
1782 LOGP(DLLAPDM, LOGL_ERROR, "SAPI != 0 but contention"
1783 "resolution (discarding)\n");
1785 return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
1787 /* transmit a SABM command with the P bit set to "1". The SABM
1788 * command shall contain the layer 3 message unit */
1789 length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
1790 LOGP(DLLAPDM, LOGL_INFO, "perform establishment with content "
1793 /* normal establishment procedure */
1795 LOGP(DLLAPDM, LOGL_INFO, "perform normal establishm. (SABM)\n");
1798 /* check if the layer3 message length exceeds N201 */
1799 if (length + 3 > 21) { /* FIXME: do we know the channel N201? */
1800 LOGP(DLLAPDM, LOGL_ERROR, "frame too large: %d > N201(%d) "
1801 "(discarding)\n", length + 3, 21);
1803 return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
1806 /* Flush send-queue */
1807 /* Clear send-buffer */
1808 lapdm_dl_flush_send(dl);
1810 /* Discard partly received L3 message */
1811 if (dl->rcv_buffer) {
1812 msgb_free(dl->rcv_buffer);
1813 dl->rcv_buffer = NULL;
1816 /* Remove RLL header from msgb */
1819 /* Push LAPDm header on msgb */
1820 msg->l2h = msgb_push(msg, 3);
1821 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
1822 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
1823 msg->l2h[2] = LAPDm_LEN(length);
1824 /* Transmit-buffer carries exactly one segment */
1825 memcpy(dl->tx_hist[0], msg->l2h, 3 + length);
1826 dl->tx_length[0] = 3 + length;
1827 /* set Vs to 0, because it is used as index when resending SABM */
1831 dl->own_busy = dl->peer_busy = 0;
1832 dl->retrans_ctr = 0;
1833 lapdm_dl_newstate(dl, LAPDm_STATE_SABM_SENT);
1835 /* Tramsmit and start T200 */
1836 osmo_timer_schedule(&dl->t200, T200);
1837 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
1840 /* L3 requests transfer of unnumbered information */
1841 static int rslms_rx_rll_udata_req(struct msgb *msg, struct lapdm_datalink *dl)
1843 struct lapdm_entity *le = dl->entity;
1844 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1845 uint8_t chan_nr = rllh->chan_nr;
1846 uint8_t link_id = rllh->link_id;
1847 uint8_t sapi = link_id & 7;
1848 struct tlv_parsed tv;
1850 uint8_t n201 = 23; //FIXME
1851 uint8_t ta = 0, tx_power = 0;
1853 /* check if the layer3 message length exceeds N201 */
1855 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1857 if (TLVP_PRESENT(&tv, RSL_IE_TIMING_ADVANCE)) {
1858 ta = *TLVP_VAL(&tv, RSL_IE_TIMING_ADVANCE);
1860 if (TLVP_PRESENT(&tv, RSL_IE_MS_POWER)) {
1861 tx_power = *TLVP_VAL(&tv, RSL_IE_MS_POWER);
1863 if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
1864 LOGP(DLLAPDM, LOGL_ERROR, "unit data request without message "
1869 msg->l3h = TLVP_VAL(&tv, RSL_IE_L3_INFO);
1870 length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
1871 /* check if the layer3 message length exceeds N201 */
1872 if (length + 5 > 23) { /* FIXME: do we know the channel N201? */
1873 LOGP(DLLAPDM, LOGL_ERROR, "frame too large: %d > N201(%d) "
1874 "(discarding)\n", length + 5, 23);
1879 LOGP(DLLAPDM, LOGL_INFO, "sending unit data (tx_power=%d, ta=%d)\n",
1882 /* Remove RLL header from msgb */
1885 /* Push L1 + LAPDm header on msgb */
1886 msg->l2h = msgb_push(msg, 2 + 3);
1887 msg->l2h[0] = tx_power;
1889 msg->l2h[2] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
1890 msg->l2h[3] = LAPDm_CTRL_U(LAPDm_U_UI, 0);
1891 msg->l2h[4] = LAPDm_LEN(length);
1892 // FIXME: short L2 header support
1895 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
1898 /* L3 requests transfer of acknowledged information */
1899 static int rslms_rx_rll_data_req(struct msgb *msg, struct lapdm_datalink *dl)
1901 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1902 struct tlv_parsed tv;
1904 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1905 if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
1906 LOGP(DLLAPDM, LOGL_ERROR, "data request without message "
1911 msg->l3h = TLVP_VAL(&tv, RSL_IE_L3_INFO);
1913 LOGP(DLLAPDM, LOGL_INFO, "writing message to send-queue\n");
1915 /* Remove the RSL/RLL header */
1918 /* Write data into the send queue */
1919 msgb_enqueue(&dl->send_queue, msg);
1921 /* Send message, if possible */
1922 rslms_send_i(&dl->mctx, __LINE__);
1926 /* Send next I frame from queued/buffered data */
1927 static int rslms_send_i(struct lapdm_msg_ctx *mctx, int line)
1929 struct lapdm_datalink *dl = mctx->dl;
1930 struct lapdm_entity *le = dl->entity;
1931 uint8_t chan_nr = mctx->chan_nr;
1932 uint8_t link_id = mctx->link_id;
1933 uint8_t sapi = link_id & 7;
1934 int k = k_sapi[sapi];
1937 int rc = - 1; /* we sent nothing */
1939 LOGP(DLLAPDM, LOGL_INFO, "%s() called from line %d\n", __func__, line);
1943 if (dl->peer_busy) {
1944 LOGP(DLLAPDM, LOGL_INFO, "peer busy, not sending\n");
1948 if (dl->state == LAPDm_STATE_TIMER_RECOV) {
1949 LOGP(DLLAPDM, LOGL_INFO, "timer recovery, not sending\n");
1953 /* If the send state variable V(S) is equal to V(A) plus k
1954 * (where k is the maximum number of outstanding I frames - see
1955 * subclause 5.8.4), the data link layer entity shall not transmit any
1956 * new I frames, but shall retransmit an I frame as a result
1957 * of the error recovery procedures as described in subclauses 5.5.4 and
1959 if (dl->V_send == add_mod8(dl->V_ack, k)) {
1960 LOGP(DLLAPDM, LOGL_INFO, "k frames outstanding, not sending "
1961 "more (k=%u V(S)=%u V(A)=%u)\n", k, dl->V_send,
1966 /* if we have no tx_hist yet, we create it */
1967 if (!dl->tx_length[dl->V_send]) {
1968 /* Get next message into send-buffer, if any */
1969 if (!dl->send_buffer) {
1972 dl->send_buffer = msgb_dequeue(&dl->send_queue);
1973 /* No more data to be sent */
1974 if (!dl->send_buffer)
1976 LOGP(DLLAPDM, LOGL_INFO, "get message from "
1980 /* How much is left in the send-buffer? */
1981 left = msgb_l3len(dl->send_buffer) - dl->send_out;
1982 /* Segment, if data exceeds N201 */
1984 if (length > mctx->n201 - 3)
1985 length = mctx->n201 - 3;
1986 LOGP(DLLAPDM, LOGL_INFO, "msg-len %d sent %d left %d N201 %d "
1987 "length %d first byte %02x\n",
1988 msgb_l3len(dl->send_buffer), dl->send_out, left,
1989 mctx->n201, length, dl->send_buffer->l3h[0]);
1990 /* If message in send-buffer is completely sent */
1992 msgb_free(dl->send_buffer);
1993 dl->send_buffer = NULL;
1997 LOGP(DLLAPDM, LOGL_INFO, "send I frame %sV(S)=%d\n",
1998 (left > length) ? "segment " : "", dl->V_send);
2000 /* Create I frame (segment) and transmit-buffer content */
2001 msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
2002 msg->l2h = msgb_put(msg, 3 + length);
2003 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
2004 msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
2005 msg->l2h[2] = LAPDm_LEN(length);
2007 msg->l2h[2] |= LAPDm_MORE;
2008 memcpy(msg->l2h + 3, dl->send_buffer->l3h + dl->send_out,
2010 memcpy(dl->tx_hist[dl->V_send], msg->l2h, 3 + length);
2011 dl->tx_length[dl->V_send] = 3 + length;
2012 /* Add length to track how much is already in the tx buffer */
2013 dl->send_out += length;
2015 LOGP(DLLAPDM, LOGL_INFO, "resend I frame from tx buffer "
2016 "V(S)=%d\n", dl->V_send);
2018 /* Create I frame (segment) from tx_hist */
2019 length = dl->tx_length[dl->V_send];
2020 msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
2021 msg->l2h = msgb_put(msg, length);
2022 memcpy(msg->l2h, dl->tx_hist[dl->V_send], length);
2023 msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
2026 /* The value of the send state variable V(S) shall be incremented by 1
2027 * at the end of the transmission of the I frame */
2028 dl->V_send = inc_mod8(dl->V_send);
2030 /* If timer T200 is not running at the time right before transmitting a
2031 * frame, when the PH-READY-TO-SEND primitive is received from the
2032 * physical layer., it shall be set. */
2033 if (!osmo_timer_pending(&dl->t200))
2034 osmo_timer_schedule(&dl->t200, T200);
2036 tx_ph_data_enqueue(dl, msg, chan_nr, link_id, mctx->n201);
2038 rc = 0; /* we sent something */
2042 /* L3 requests suspension of data link */
2043 static int rslms_rx_rll_susp_req(struct msgb *msg, struct lapdm_datalink *dl)
2045 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
2046 uint8_t sapi = rllh->link_id & 7;
2049 LOGP(DLLAPDM, LOGL_ERROR, "SAPI != 0 while suspending\n");
2054 LOGP(DLLAPDM, LOGL_INFO, "perform suspension\n");
2056 /* put back the send-buffer to the send-queue (first position) */
2057 if (dl->send_buffer) {
2058 LOGP(DLLAPDM, LOGL_INFO, "put frame in sendbuffer back to "
2060 llist_add(&dl->send_buffer->list, &dl->send_queue);
2061 dl->send_buffer = NULL;
2063 LOGP(DLLAPDM, LOGL_INFO, "no frame in sendbuffer\n");
2065 /* Clear transmit buffer, but keep send buffer */
2066 lapdm_dl_flush_tx(dl);
2070 return send_rll_simple(RSL_MT_SUSP_CONF, &dl->mctx);
2073 /* L3 requests resume of data link */
2074 static int rslms_rx_rll_res_req(struct msgb *msg, struct lapdm_datalink *dl)
2076 struct lapdm_entity *le = dl->entity;
2077 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
2078 uint8_t chan_nr = rllh->chan_nr;
2079 uint8_t link_id = rllh->link_id;
2080 uint8_t sapi = rllh->link_id & 7;
2081 struct tlv_parsed tv;
2083 uint8_t n201 = 23; //FIXME
2085 /* Set chan_nr and link_id for established connection */
2086 memset(&dl->mctx, 0, sizeof(dl->mctx));
2088 dl->mctx.n201 = n201;
2089 dl->mctx.chan_nr = chan_nr;
2090 dl->mctx.link_id = link_id;
2092 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
2093 if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
2094 LOGP(DLLAPDM, LOGL_ERROR, "resume without message error\n");
2096 return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
2098 length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
2100 LOGP(DLLAPDM, LOGL_INFO, "perform re-establishment (SABM) length=%d\n",
2103 /* Replace message in the send-buffer (reconnect) */
2104 if (dl->send_buffer)
2105 msgb_free(dl->send_buffer);
2108 /* Remove the RSL/RLL header */
2110 /* Write data into the send buffer, to be sent first */
2111 dl->send_buffer = msg;
2114 /* Discard partly received L3 message */
2115 if (dl->rcv_buffer) {
2116 msgb_free(dl->rcv_buffer);
2117 dl->rcv_buffer = NULL;
2120 /* Create new msgb (old one is now free) */
2121 msg = msgb_alloc_headroom(23+10, 10, "LAPDm SABM");
2122 msg->l2h = msgb_put(msg, 3);
2123 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
2124 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
2125 msg->l2h[2] = LAPDm_LEN(0);
2126 /* Transmit-buffer carries exactly one segment */
2127 memcpy(dl->tx_hist[0], msg->l2h, 3);
2128 dl->tx_length[0] = 3;
2129 /* set Vs to 0, because it is used as index when resending SABM */
2133 dl->own_busy = dl->peer_busy = 0;
2134 dl->retrans_ctr = 0;
2135 lapdm_dl_newstate(dl, LAPDm_STATE_SABM_SENT);
2137 /* Tramsmit and start T200 */
2138 osmo_timer_schedule(&dl->t200, T200);
2139 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
2142 /* L3 requests release of data link */
2143 static int rslms_rx_rll_rel_req(struct msgb *msg, struct lapdm_datalink *dl)
2145 struct lapdm_entity *le = dl->entity;
2146 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
2147 uint8_t chan_nr = rllh->chan_nr;
2148 uint8_t link_id = rllh->link_id;
2149 uint8_t sapi = rllh->link_id & 7;
2152 /* get release mode */
2153 if (rllh->data[0] == RSL_IE_RELEASE_MODE)
2154 mode = rllh->data[1] & 1;
2158 LOGP(DLLAPDM, LOGL_INFO, "perform local release\n");
2160 /* reset Timer T200 */
2161 osmo_timer_del(&dl->t200);
2162 /* enter idle state */
2163 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
2165 lapdm_dl_flush_tx(dl);
2166 lapdm_dl_flush_send(dl);
2167 /* send notification to L3 */
2168 return send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
2171 /* in case we are already disconnecting */
2172 if (dl->state == LAPDm_STATE_DISC_SENT)
2175 LOGP(DLLAPDM, LOGL_INFO, "perform normal release (DISC)\n");
2178 msgb_pull(msg, msg->tail - msg->l2h);
2180 /* Push LAPDm header on msgb */
2181 msg->l2h = msgb_push(msg, 3);
2182 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
2183 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_DISC, 1);
2184 msg->l2h[2] = LAPDm_LEN(0);
2185 /* Transmit-buffer carries exactly one segment */
2186 memcpy(dl->tx_hist[0], msg->l2h, 3);
2187 dl->tx_length[0] = 3;
2190 dl->own_busy = dl->peer_busy = 0;
2191 dl->retrans_ctr = 0;
2192 lapdm_dl_newstate(dl, LAPDm_STATE_DISC_SENT);
2194 /* Tramsmit and start T200 */
2195 osmo_timer_schedule(&dl->t200, T200);
2196 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, dl->mctx.n201);
2199 /* L3 requests release in idle state */
2200 static int rslms_rx_rll_rel_req_idle(struct msgb *msg, struct lapdm_datalink *dl)
2204 /* send notification to L3 */
2205 return send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
2208 /* L3 requests channel in idle state */
2209 static int rslms_rx_chan_rqd(struct lapdm_channel *lc, struct msgb *msg)
2211 struct abis_rsl_cchan_hdr *cch = msgb_l2(msg);
2212 void *l1ctx = lc->lapdm_dcch.l1_ctx;
2213 struct osmo_phsap_prim pp;
2215 osmo_prim_init(&pp.oph, SAP_GSM_PH, PRIM_PH_RACH,
2216 PRIM_OP_REQUEST, NULL);
2218 if (msgb_l2len(msg) < sizeof(*cch) + 4 + 2 + 2) {
2219 LOGP(DLLAPDM, LOGL_ERROR, "Message too short for CHAN RQD!\n");
2222 if (cch->data[0] != RSL_IE_REQ_REFERENCE) {
2223 LOGP(DLLAPDM, LOGL_ERROR, "Missing REQ REFERENCE IE\n");
2226 pp.u.rach_req.ra = cch->data[1];
2227 pp.u.rach_req.offset = ((cch->data[2] & 0x7f) << 8) | cch->data[3];
2228 pp.u.rach_req.is_combined_ccch = cch->data[2] >> 7;
2230 if (cch->data[4] != RSL_IE_ACCESS_DELAY) {
2231 LOGP(DLLAPDM, LOGL_ERROR, "Missing ACCESS_DELAY IE\n");
2234 /* TA = 0 - delay */
2235 pp.u.rach_req.ta = 0 - cch->data[5];
2237 if (cch->data[6] != RSL_IE_MS_POWER) {
2238 LOGP(DLLAPDM, LOGL_ERROR, "Missing MS POWER IE\n");
2241 pp.u.rach_req.tx_power = cch->data[7];
2245 return lc->lapdm_dcch.l1_prim_cb(&pp.oph, l1ctx);
2248 /* L1 confirms channel request */
2249 static int l2_ph_chan_conf(struct msgb *msg, struct lapdm_entity *le, uint32_t frame_nr)
2251 struct abis_rsl_cchan_hdr *ch;
2253 struct gsm48_req_ref *ref;
2255 gsm_fn2gsmtime(&tm, frame_nr);
2258 msg->l2h = msgb_push(msg, sizeof(*ch) + sizeof(*ref));
2259 ch = (struct abis_rsl_cchan_hdr *)msg->l2h;
2260 rsl_init_cchan_hdr(ch, RSL_MT_CHAN_CONF);
2261 ch->chan_nr = RSL_CHAN_RACH;
2262 ch->data[0] = RSL_IE_REQ_REFERENCE;
2263 ref = (struct gsm48_req_ref *) (ch->data + 1);
2266 ref->t3_low = tm.t3 & 0x7;
2267 ref->t3_high = tm.t3 >> 3;
2269 return rslms_sendmsg(msg, le);
2272 const char *lapdm_state_names[] = {
2275 "LAPDm_STATE_SABM_SENT",
2276 "LAPDm_STATE_MF_EST",
2277 "LAPDm_STATE_TIMER_RECOV",
2278 "LAPDm_STATE_DISC_SENT",
2281 /* statefull handling for RSLms RLL messages from L3 */
2282 static struct l2downstate {
2285 int (*rout) (struct msgb *msg, struct lapdm_datalink *dl);
2286 } l2downstatelist[] = {
2287 /* create and send UI command */
2289 RSL_MT_UNIT_DATA_REQ, rslms_rx_rll_udata_req},
2291 /* create and send SABM command */
2292 {SBIT(LAPDm_STATE_IDLE),
2293 RSL_MT_EST_REQ, rslms_rx_rll_est_req},
2295 /* create and send I command */
2296 {SBIT(LAPDm_STATE_MF_EST) |
2297 SBIT(LAPDm_STATE_TIMER_RECOV),
2298 RSL_MT_DATA_REQ, rslms_rx_rll_data_req},
2300 /* suspend datalink */
2301 {SBIT(LAPDm_STATE_MF_EST) |
2302 SBIT(LAPDm_STATE_TIMER_RECOV),
2303 RSL_MT_SUSP_REQ, rslms_rx_rll_susp_req},
2305 /* create and send SABM command (resume) */
2306 {SBIT(LAPDm_STATE_MF_EST) |
2307 SBIT(LAPDm_STATE_TIMER_RECOV),
2308 RSL_MT_RES_REQ, rslms_rx_rll_res_req},
2310 /* create and send SABM command (reconnect) */
2311 {SBIT(LAPDm_STATE_IDLE) |
2312 SBIT(LAPDm_STATE_MF_EST) |
2313 SBIT(LAPDm_STATE_TIMER_RECOV),
2314 RSL_MT_RECON_REQ, rslms_rx_rll_res_req},
2316 /* create and send DISC command */
2317 {SBIT(LAPDm_STATE_SABM_SENT) |
2318 SBIT(LAPDm_STATE_MF_EST) |
2319 SBIT(LAPDm_STATE_TIMER_RECOV) |
2320 SBIT(LAPDm_STATE_DISC_SENT),
2321 RSL_MT_REL_REQ, rslms_rx_rll_rel_req},
2323 /* release in idle state */
2324 {SBIT(LAPDm_STATE_IDLE),
2325 RSL_MT_REL_REQ, rslms_rx_rll_rel_req_idle},
2328 #define L2DOWNSLLEN \
2329 (sizeof(l2downstatelist) / sizeof(struct l2downstate))
2331 /* incoming RSLms RLL message from L3 */
2332 static int rslms_rx_rll(struct msgb *msg, struct lapdm_channel *lc)
2334 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
2335 int msg_type = rllh->c.msg_type;
2336 uint8_t sapi = rllh->link_id & 7;
2337 struct lapdm_entity *le;
2338 struct lapdm_datalink *dl;
2339 int i, supported = 0;
2342 if (msgb_l2len(msg) < sizeof(*rllh)) {
2343 LOGP(DLLAPDM, LOGL_ERROR, "Message too short for RLL hdr!\n");
2347 if (rllh->link_id & 0x40)
2348 le = &lc->lapdm_acch;
2350 le = &lc->lapdm_dcch;
2352 /* G.2.1 No action schall be taken on frames containing an unallocated
2355 dl = datalink_for_sapi(le, sapi);
2357 LOGP(DLLAPDM, LOGL_ERROR, "No instance for SAPI %d!\n", sapi);
2361 LOGP(DLLAPDM, LOGL_INFO, "(%p) RLL Message '%s' received in state %s\n",
2362 lc->name, rsl_msg_name(msg_type), lapdm_state_names[dl->state]);
2364 /* find function for current state and message */
2365 for (i = 0; i < L2DOWNSLLEN; i++) {
2366 if (msg_type == l2downstatelist[i].type)
2368 if ((msg_type == l2downstatelist[i].type)
2369 && ((1 << dl->state) & l2downstatelist[i].states))
2373 LOGP(DLLAPDM, LOGL_NOTICE, "Message unsupported.\n");
2377 if (i == L2DOWNSLLEN) {
2378 LOGP(DLLAPDM, LOGL_NOTICE, "Message unhandled at this state.\n");
2383 rc = l2downstatelist[i].rout(msg, dl);
2388 /* incoming RSLms COMMON CHANNEL message from L3 */
2389 static int rslms_rx_com_chan(struct msgb *msg, struct lapdm_channel *lc)
2391 struct abis_rsl_cchan_hdr *cch = msgb_l2(msg);
2392 int msg_type = cch->c.msg_type;
2395 if (msgb_l2len(msg) < sizeof(*cch)) {
2396 LOGP(DLLAPDM, LOGL_ERROR, "Message too short for COM CHAN hdr!\n");
2401 case RSL_MT_CHAN_RQD:
2402 /* create and send RACH request */
2403 rc = rslms_rx_chan_rqd(lc, msg);
2406 LOGP(DLLAPDM, LOGL_NOTICE, "Unknown COMMON CHANNEL msg %d!\n",
2415 /* input into layer2 (from layer 3) */
2416 int lapdm_rslms_recvmsg(struct msgb *msg, struct lapdm_channel *lc)
2418 struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
2421 if (msgb_l2len(msg) < sizeof(*rslh)) {
2422 LOGP(DLLAPDM, LOGL_ERROR, "Message too short RSL hdr!\n");
2426 switch (rslh->msg_discr & 0xfe) {
2427 case ABIS_RSL_MDISC_RLL:
2428 rc = rslms_rx_rll(msg, lc);
2430 case ABIS_RSL_MDISC_COM_CHAN:
2431 rc = rslms_rx_com_chan(msg, lc);
2434 LOGP(DLLAPDM, LOGL_ERROR, "unknown RSLms message "
2435 "discriminator 0x%02x", rslh->msg_discr);
2443 int lapdm_entity_set_mode(struct lapdm_entity *le, enum lapdm_mode mode)
2447 le->cr.loc2rem.cmd = CR_MS2BS_CMD;
2448 le->cr.loc2rem.resp = CR_MS2BS_RESP;
2449 le->cr.rem2loc.cmd = CR_BS2MS_CMD;
2450 le->cr.rem2loc.resp = CR_BS2MS_RESP;
2452 case LAPDM_MODE_BTS:
2453 le->cr.loc2rem.cmd = CR_BS2MS_CMD;
2454 le->cr.loc2rem.resp = CR_BS2MS_RESP;
2455 le->cr.rem2loc.cmd = CR_MS2BS_CMD;
2456 le->cr.rem2loc.resp = CR_MS2BS_RESP;
2467 int lapdm_channel_set_mode(struct lapdm_channel *lc, enum lapdm_mode mode)
2471 rc = lapdm_entity_set_mode(&lc->lapdm_dcch, mode);
2475 return lapdm_entity_set_mode(&lc->lapdm_acch, mode);
2478 void lapdm_channel_set_l1(struct lapdm_channel *lc, osmo_prim_cb cb, void *ctx)
2480 lc->lapdm_dcch.l1_prim_cb = cb;
2481 lc->lapdm_acch.l1_prim_cb = cb;
2482 lc->lapdm_dcch.l1_ctx = ctx;
2483 lc->lapdm_acch.l1_ctx = ctx;
2486 void lapdm_channel_set_l3(struct lapdm_channel *lc, lapdm_cb_t cb, void *ctx)
2488 lc->lapdm_dcch.l3_cb = cb;
2489 lc->lapdm_acch.l3_cb = cb;
2490 lc->lapdm_dcch.l3_ctx = ctx;
2491 lc->lapdm_acch.l3_ctx = ctx;
2494 void lapdm_entity_reset(struct lapdm_entity *le)
2496 struct lapdm_datalink *dl;
2499 for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
2500 dl = &le->datalink[i];
2501 if (dl->state == LAPDm_STATE_IDLE)
2503 LOGP(DLLAPDM, LOGL_INFO, "Resetting LAPDm instance\n");
2504 /* reset Timer T200 */
2505 osmo_timer_del(&dl->t200);
2506 /* enter idle state */
2507 dl->state = LAPDm_STATE_IDLE;
2509 lapdm_dl_flush_tx(dl);
2510 lapdm_dl_flush_send(dl);
2514 void lapdm_channel_reset(struct lapdm_channel *lc)
2516 lapdm_entity_reset(&lc->lapdm_dcch);
2517 lapdm_entity_reset(&lc->lapdm_acch);
2520 void lapdm_entity_set_flags(struct lapdm_entity *le, unsigned int flags)
2525 void lapdm_channel_set_flags(struct lapdm_channel *lc, unsigned int flags)
2527 lapdm_entity_set_flags(&lc->lapdm_dcch, flags);
2528 lapdm_entity_set_flags(&lc->lapdm_acch, flags);