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libosmocore/src/isdn/v110_ta.c

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/*! \file v110_ta.c
* TA (Terminal Adapter) implementation as per ITU-T V.110. */
/*
* (C) 2022 by Harald Welte <laforge@gnumonks.org>
* (C) 2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
*
* Initial (Work-in-Progress) implementation by Harald Welte,
* completed and co-authored by Vadim Yanitskiy.
*
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <stdbool.h>
#include <stdint.h>
#include <errno.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/bits.h>
#include <osmocom/core/tdef.h>
#include <osmocom/core/fsm.h>
#include <osmocom/isdn/v110.h>
#include <osmocom/isdn/v110_ta.h>
#define S(x) (1 << (x))
#define V24_FLAGMASK_IS_ON(flags, circuit) \
(((flags) & S(circuit)) != 0)
#define V24_FLAGMASK_IS_OFF(flags, circuit) \
(((flags) & S(circuit)) == 0)
#define V24_FLAGMASK_SET_ON(flags, circuit) \
(flags) |= S(circuit)
#define V24_FLAGMASK_SET_OFF(flags, circuit) \
(flags) &= ~S(circuit)
/* inverse logic: ON = binary 0; OFF = binary 1 */
#define V110_SX_BIT_ON 0
#define V110_SX_BIT_OFF 1
const struct value_string osmo_v110_ta_circuit_names[] = {
{ OSMO_V110_TA_C_105, "105/RTS" },
{ OSMO_V110_TA_C_106, "106/CTS" },
{ OSMO_V110_TA_C_107, "107/DSR" },
{ OSMO_V110_TA_C_108, "108/DTR" },
{ OSMO_V110_TA_C_109, "109/DCD" },
{ OSMO_V110_TA_C_133, "133" },
{ 0, NULL }
};
const struct value_string osmo_v110_ta_circuit_descs[] = {
{ OSMO_V110_TA_C_105, "Request to Send" },
{ OSMO_V110_TA_C_106, "Clear to Send" },
{ OSMO_V110_TA_C_107, "Data Set Ready" },
{ OSMO_V110_TA_C_108, "Data Terminal Ready" },
{ OSMO_V110_TA_C_109, "Data Carrier Detect" },
{ OSMO_V110_TA_C_133, "Ready for receiving" },
{ 0, NULL }
};
static const struct osmo_tdef v110_ta_tdef[] = {
{ .T = OSMO_V110_TA_TIMER_X1,
.unit = OSMO_TDEF_MS, .default_val = 3000, /* suggested in 7.1.5 e) */
.desc = "ITU-T V.110 7.1.5 Loss of frame synchronization: sync recovery timer" },
{ .T = OSMO_V110_TA_TIMER_T1,
.unit = OSMO_TDEF_MS, .default_val = 10000, /* suggested in 7.1.2.2 */
.desc = "ITU-T V.110 7.1.2 Connect TA to line: sync establishment timer" },
{ .T = OSMO_V110_TA_TIMER_T2,
.unit = OSMO_TDEF_MS, .default_val = 5000, /* suggested in 7.1.4.1 */
.desc = "ITU-T V.110 7.1.4 Disconnect mode: disconnect confirmation timer" },
{ /* end of list */ }
};
/*********************************************************************************
* V.110 TERMINAL ADAPTER FSM
*********************************************************************************/
enum v110_ta_fsm_state {
V110_TA_ST_IDLE_READY, /* 7.1.1 Idle (or ready) state */
V110_TA_ST_CON_TA_TO_LINE, /* 7.1.2 Connect TA to line state */
V110_TA_ST_DATA_TRANSFER, /* 7.1.3 Data transfer state */
V110_TA_ST_DISCONNECTING, /* 7.1.4 Disconnect mode */
V110_TA_ST_RESYNCING, /* 7.1.5 Re-synchronizing state */
};
enum v110_ta_fsm_event {
V110_TA_EV_RX_FRAME_IND, /* a V.110 frame was received by the lower layer */
V110_TA_EV_TX_FRAME_RTS, /* a V.110 frame is to be sent by the lower layer */
V110_TA_EV_V24_STATUS_CHG, /* V.24 flag-mask has been updated by TE */
V110_TA_EV_SYNC_IND, /* the lower layer has synchronized to the frame clock */
V110_TA_EV_DESYNC_IND, /* the lower layer has lost frame clock synchronization */
V110_TA_EV_TIMEOUT, /* generic event for handling a timeout condition */
};
static const struct value_string v110_ta_fsm_event_names[] = {
{ V110_TA_EV_RX_FRAME_IND, "RX_FRAME_IND" },
{ V110_TA_EV_TX_FRAME_RTS, "TX_FRAME_RTS" },
{ V110_TA_EV_V24_STATUS_CHG, "V24_STATUS_CHG" },
{ V110_TA_EV_SYNC_IND, "SYNC_IND" },
{ V110_TA_EV_DESYNC_IND, "DESYNC_IND" },
{ V110_TA_EV_TIMEOUT, "TIMEOUT" },
{ 0, NULL }
};
enum v110_ta_d_bit_mode {
V110_TA_DBIT_M_ALL_ZERO = 0, /* set all bits to binary '0' */
V110_TA_DBIT_M_ALL_ONE = 1, /* set all bits to binary '1' */
V110_TA_DBIT_M_FORWARD, /* forward D-bits to/from DTE */
};
struct v110_ta_state {
/*! V.24 status flags shared between DTE (user) and DCE (TA, us) */
unsigned int v24_flags;
struct {
/* what kind of D-bits to transmit in V.110 frames */
enum v110_ta_d_bit_mode d_bit_mode;
/* what to put in S-bits of transmitted V.110 frames */
ubit_t s_bits;
/* what to put in X-bits of transmitted V.110 frames */
ubit_t x_bits;
} tx;
struct {
enum v110_ta_d_bit_mode d_bit_mode;
} rx;
};
struct osmo_v110_ta {
const char *name;
struct osmo_tdef *Tdefs;
struct osmo_fsm_inst *fi;
struct osmo_v110_ta_cfg *cfg;
struct v110_ta_state state;
};
static inline bool v110_df_x_bits_are(const struct osmo_v110_decoded_frame *df, ubit_t cmp)
{
return (df->x_bits[0] == cmp) && (df->x_bits[1] == cmp);
}
static inline bool v110_df_s_bits_are(const struct osmo_v110_decoded_frame *df, ubit_t cmp)
{
/* ITU-T Table 2/V.110 (see also 5.1.2.3) defines the following S-bits:
* S1, S3, S4, S6, S8, S9 (6 bits total). However, fr->s_bits[] contains
* 9 (MAX_S_BITS) bits, including the undefined bits S2, S5, S7.
* Hence we must skip those undefined bits. */
static const uint8_t sbit_map[] = { 0, 2, 3, 5, 7, 8 };
for (unsigned int i = 0; i < ARRAY_SIZE(sbit_map); i++) {
uint8_t idx = sbit_map[i];
if (df->s_bits[idx] != cmp)
return false;
}
return true;
}
static inline bool v110_df_d_bits_are(const struct osmo_v110_decoded_frame *df, ubit_t cmp)
{
for (unsigned int i = 0; i < MAX_D_BITS; i++) {
if (df->d_bits[i] != cmp)
return false;
}
return true;
}
/* handle one V.110 frame and forward user bits to the application */
static void v110_ta_handle_frame(const struct osmo_v110_ta *ta,
const struct osmo_v110_decoded_frame *df)
{
const struct osmo_v110_ta_cfg *cfg = ta->cfg;
const struct v110_ta_state *ts = &ta->state;
ubit_t user_bits[MAX_D_BITS];
int num_user_bits;
int rc;
switch (ts->rx.d_bit_mode) {
case V110_TA_DBIT_M_ALL_ZERO:
case V110_TA_DBIT_M_ALL_ONE:
/* generate as many user bits as needed for the configured rate */
num_user_bits = osmo_v110_sync_ra1_get_user_data_chunk_bitlen(cfg->rate);
OSMO_ASSERT(num_user_bits > 0);
/* set them all to binary '0' or binary '1' */
memset(&user_bits[0], (int)ts->rx.d_bit_mode, num_user_bits);
cfg->rx_cb(cfg->priv, &user_bits[0], num_user_bits);
break;
case V110_TA_DBIT_M_FORWARD:
rc = osmo_v110_sync_ra1_ir_to_user(cfg->rate, &user_bits[0], sizeof(user_bits), df);
if (rc > 0)
cfg->rx_cb(cfg->priv, &user_bits[0], rc);
/* XXX else: indicate an error somehow? */
break;
}
}
/* build one V.110 frame to transmit */
static void v110_ta_build_frame(const struct osmo_v110_ta *ta,
struct osmo_v110_decoded_frame *df)
{
const struct osmo_v110_ta_cfg *cfg = ta->cfg;
const struct v110_ta_state *ts = &ta->state;
ubit_t user_bits[MAX_D_BITS];
int num_user_bits;
int rc;
/* E-bits (E1/E2/E3 may be overwritten below) */
memset(df->e_bits, 1, sizeof(df->e_bits));
/* S-bits */
memset(df->s_bits, ts->tx.s_bits, sizeof(df->s_bits));
/* X-bits */
memset(df->x_bits, ts->tx.x_bits, sizeof(df->x_bits));
/* D-bits */
switch (ts->tx.d_bit_mode) {
case V110_TA_DBIT_M_ALL_ZERO:
case V110_TA_DBIT_M_ALL_ONE:
/* set them all to binary '0' or binary '1' */
memset(df->d_bits, (int)ts->tx.d_bit_mode, sizeof(df->d_bits));
break;
case V110_TA_DBIT_M_FORWARD:
/* how many user bits to retrieve */
num_user_bits = osmo_v110_sync_ra1_get_user_data_chunk_bitlen(cfg->rate);
OSMO_ASSERT(num_user_bits > 0);
/* retrieve user bits from the application */
cfg->tx_cb(cfg->priv, &user_bits[0], num_user_bits);
/* convert user bits to intermediate rate (store to df) */
rc = osmo_v110_sync_ra1_user_to_ir(cfg->rate, df, &user_bits[0], num_user_bits);
OSMO_ASSERT(rc == 0);
break;
}
}
static void v110_ta_flags_update(struct osmo_v110_ta *ta, unsigned int v24_flags)
{
struct osmo_v110_ta_cfg *cfg = ta->cfg;
if (ta->state.v24_flags == v24_flags)
return;
if (cfg->status_update_cb != NULL)
cfg->status_update_cb(cfg->priv, v24_flags);
ta->state.v24_flags = v24_flags;
}
static const struct osmo_tdef_state_timeout v110_ta_fsm_timeouts[32] = {
[V110_TA_ST_RESYNCING] = { .T = OSMO_V110_TA_TIMER_X1 },
[V110_TA_ST_CON_TA_TO_LINE] = { .T = OSMO_V110_TA_TIMER_T1 },
[V110_TA_ST_DISCONNECTING] = { .T = OSMO_V110_TA_TIMER_T2 },
};
#define v110_ta_fsm_state_chg(state) \
osmo_tdef_fsm_inst_state_chg(fi, state, \
v110_ta_fsm_timeouts, \
((struct osmo_v110_ta *)(fi->priv))->Tdefs, \
0)
/* ITU-T V.110 Section 7.1.1 */
static void v110_ta_fsm_idle_ready_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
unsigned int v24_flags = ta->state.v24_flags;
/* 7.1.1.2 During the idle (or ready) state the TA will transmit continuous binary 1s into the B-channel */
ts->tx.d_bit_mode = V110_TA_DBIT_M_ALL_ONE; /* circuit 103: continuous binary '1' */
ts->tx.s_bits = V110_SX_BIT_OFF; /* OFF is binary '1' */
ts->tx.x_bits = V110_SX_BIT_OFF; /* OFF is binary '1' */
/* 7.1.1.3 During the idle (or ready) state the TA (DCE) will transmit the following toward the DTE: */
/* - circuit 104: continuous binary '1' */
ts->rx.d_bit_mode = V110_TA_DBIT_M_ALL_ONE;
/* - circuits 107, 106, 109 = OFF */
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_106);
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_107);
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_109);
v110_ta_flags_update(ta, v24_flags);
}
/* ITU-T V.110 Section 7.1.1 */
static void v110_ta_fsm_idle_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
switch (event) {
case V110_TA_EV_V24_STATUS_CHG:
/* When the TA is to be switched to the data mode, circuit 108 must be ON */
if (V24_FLAGMASK_IS_ON(ts->v24_flags, OSMO_V110_TA_C_108)) {
/* 7.12.2: Start timer T1 when switching to CON_TA_LINE */
v110_ta_fsm_state_chg(V110_TA_ST_CON_TA_TO_LINE);
}
break;
case V110_TA_EV_RX_FRAME_IND:
v110_ta_handle_frame(ta, (const struct osmo_v110_decoded_frame *)data);
break;
case V110_TA_EV_TX_FRAME_RTS:
v110_ta_build_frame(ta, (struct osmo_v110_decoded_frame *)data);
break;
default:
OSMO_ASSERT(0);
}
}
/* ITU-T V.110 Section 7.1.2 */
static void v110_ta_fsm_connect_ta_to_line_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
/* 7.1.2.1 Switching to the data mode causes the TA to transmit the following towards the ISDN: */
/* a) frame synchronization pattern as described in 5.1.3.1 and 5.2.1 (done by the API user) */
/* b) circuit 103: continuous binary '1' */
ts->tx.d_bit_mode = V110_TA_DBIT_M_ALL_ONE;
/* c) status bits S = OFF and X = OFF */
ts->tx.s_bits = V110_SX_BIT_OFF; /* OFF is binary '1' */
ts->tx.x_bits = V110_SX_BIT_OFF; /* OFF is binary '1' */
/* 7.1.2.2 ... the receiver in the TA will begin to search for the frame synchronization
* pattern in the received bit stream (see 5.1.3.1 and 5.2.1) and start timer T1. */
OSMO_ASSERT(fi->T == OSMO_V110_TA_TIMER_T1);
}
/* ITU-T V.110 Section 7.1.2 */
static void v110_ta_fsm_connect_ta_to_line(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
switch (event) {
case V110_TA_EV_V24_STATUS_CHG:
/* If circuit 108 is OFF, we go back to IDLE/READY */
if (V24_FLAGMASK_IS_OFF(ts->v24_flags, OSMO_V110_TA_C_108))
v110_ta_fsm_state_chg(V110_TA_ST_IDLE_READY);
break;
case V110_TA_EV_SYNC_IND:
/* 7.1.2.3 When the receiver recognizes the frame synchronization pattern, it causes the S-
* and X-bits in the transmitted frames to be turned ON (provided that circuit 108 is ON). */
OSMO_ASSERT(V24_FLAGMASK_IS_ON(ts->v24_flags, OSMO_V110_TA_C_108));
ts->tx.s_bits = V110_SX_BIT_ON;
ts->tx.x_bits = V110_SX_BIT_ON;
break;
case V110_TA_EV_RX_FRAME_IND:
{
const struct osmo_v110_decoded_frame *df = data;
unsigned int v24_flags = ta->state.v24_flags;
/* 7.1.2.4 When the receiver recognizes that the status of bits S and X are ON */
if (v110_df_s_bits_are(df, V110_SX_BIT_ON) &&
v110_df_x_bits_are(df, V110_SX_BIT_ON)) {
/* ... it will perform the following functions: */
/* a) Turn ON circuit 107 toward the DTE and stop timer T1 */
V24_FLAGMASK_SET_ON(v24_flags, OSMO_V110_TA_C_107);
osmo_timer_del(&fi->timer);
/* b) Then, circuit 103 may be connected to the data bits in the frame; however, the
* DTE must maintain a binary 1 condition on circuit 103 until circuit 106 is turned
* ON in the next portion of the sequence. */
/* c) Turn ON circuit 109 and connect the data bits to circuit 104. */
V24_FLAGMASK_SET_ON(v24_flags, OSMO_V110_TA_C_109);
ts->rx.d_bit_mode = V110_TA_DBIT_M_FORWARD;
/* d) After an interval of N bits (see 6.3), it will turn ON circuit 106. */
V24_FLAGMASK_SET_ON(v24_flags, OSMO_V110_TA_C_106);
ts->tx.d_bit_mode = V110_TA_DBIT_M_FORWARD;
v110_ta_flags_update(ta, v24_flags);
/* Circuit 106 transitioning from OFF to ON will cause the transmitted data to
* transition from binary 1 to the data mode. */
v110_ta_fsm_state_chg(V110_TA_ST_DATA_TRANSFER);
}
v110_ta_handle_frame(ta, df);
break;
}
case V110_TA_EV_TX_FRAME_RTS:
v110_ta_build_frame(ta, (struct osmo_v110_decoded_frame *)data);
break;
case V110_TA_EV_TIMEOUT:
v110_ta_fsm_state_chg(V110_TA_ST_IDLE_READY);
break;
default:
OSMO_ASSERT(0);
}
}
/* ITU-T V.110 Section 7.1.3 */
static void v110_ta_fsm_data_transfer_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
unsigned int v24_flags = ta->state.v24_flags;
/* 7.1.3.1 While in the data transfer state, the following circuit conditions exist:
* a): 105, 107, 108, and 109 are in the ON condition */
/* XXX: OSMO_ASSERT(V24_FLAGMASK_IS_ON(ts->v24_flags, OSMO_V110_TA_C_105)); */
V24_FLAGMASK_SET_ON(v24_flags, OSMO_V110_TA_C_107);
/* XXX: OSMO_ASSERT(V24_FLAGMASK_IS_ON(ts->v24_flags, OSMO_V110_TA_C_108)); */
V24_FLAGMASK_SET_ON(v24_flags, OSMO_V110_TA_C_109);
/* b) data is being transmitted on circuit 103 and received on circuit 104 */
ts->rx.d_bit_mode = V110_TA_DBIT_M_FORWARD;
ts->tx.d_bit_mode = V110_TA_DBIT_M_FORWARD;
/* c) circuits 133 (when implemented) and 106 are in the ON condition unless local out-of-band
* flow control is being used, either or both circuits may be in the ON or the OFF condition. */
if (!ta->cfg->flow_ctrl.end_to_end) {
/* XXX: OSMO_ASSERT(V24_FLAGMASK_IS_ON(ts->v24_flags, OSMO_V110_TA_C_133)); */
V24_FLAGMASK_SET_ON(v24_flags, OSMO_V110_TA_C_106);
}
v110_ta_flags_update(ta, v24_flags);
/* 7.1.3.2 While in the data transfer state, the following status bit conditions exist: */
/* a) status bits S in both directions are in the ON condition; */
ts->tx.s_bits = V110_SX_BIT_ON;
/* b) status bits X in both directions are in the ON condition unless end-to-end flow control
* is being used, in which case status bit X in either or both directions may be in the
* ON or the OFF condition. */
if (!ta->cfg->flow_ctrl.end_to_end)
ts->tx.x_bits = V110_SX_BIT_ON;
}
/* ITU-T V.110 Section 7.1.3 */
static void v110_ta_fsm_data_transfer(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
/* 7.1.3.3 While in the data transfer state: */
/* a) the S status bits shall *not* be mapped to/from the interchange circuits */
/* b) the X status bits shall *not* be mapped according to Table 3,
* unless end-to-end flow control is implemented */
/* TODO: if (ta->cfg->flow_ctrl.end_to_end) { ... } */
switch (event) {
case V110_TA_EV_V24_STATUS_CHG:
/* 7.1.4.1 At the completion of the data transfer phase, the local DTE will indicate a
* disconnect request by turning OFF circuit 108 */
if (V24_FLAGMASK_IS_ON(ts->v24_flags, OSMO_V110_TA_C_108))
break;
v110_ta_fsm_state_chg(V110_TA_ST_DISCONNECTING);
break;
case V110_TA_EV_DESYNC_IND:
v110_ta_fsm_state_chg(V110_TA_ST_RESYNCING);
break;
case V110_TA_EV_TX_FRAME_RTS:
v110_ta_build_frame(ta, (struct osmo_v110_decoded_frame *)data);
break;
case V110_TA_EV_RX_FRAME_IND:
{
const struct osmo_v110_decoded_frame *df = data;
unsigned int v24_flags = ta->state.v24_flags;
/* 7.1.4.2 ... this TA will recognize the transition of the status bits S from
* ON to OFF and the data bits from data to binary 0 as a disconnect request */
if (v110_df_s_bits_are(df, V110_SX_BIT_OFF) && v110_df_d_bits_are(df, 0)) {
/* ... and it will turn OFF circuits 107 and 109. */
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_107);
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_109);
v110_ta_flags_update(ta, v24_flags);
/* DTE should respond by turning OFF circuit 108 */
break; /* XXX: shall we forward D-bits to DTE anyway? */
}
v110_ta_handle_frame(ta, df);
break;
}
default:
OSMO_ASSERT(0);
}
}
/* ITU-T V.110 Section 7.1.4 */
static void v110_ta_fsm_disconnect_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
unsigned int v24_flags = ta->state.v24_flags;
/* 7.1.4.1 At the completion of the data transfer phase, the local DTE will indicate a
* disconnect request by turning OFF circuit 108. This will cause the following to occur: */
/* a) the status bits S in the frame toward ISDN will turn OFF, status bits X are kept ON */
ts->tx.s_bits = V110_SX_BIT_OFF;
/* b) circuit 106 will be turned OFF */
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_106);
v110_ta_flags_update(ta, v24_flags);
/* c) the data bits in the frame will be set to binary 0. */
ts->tx.d_bit_mode = V110_TA_DBIT_M_ALL_ZERO;
/* To guard against the failure of the remote TA to respond to the disconnect request,
* the local TA may start a timer T2 (suggested value 5 s) which is stopped by the
* reception or transmission of any D-channel clearing message (DISCONNECT, RELEASE,
* RELEASE COMPLETE). */
OSMO_ASSERT(fi->T == OSMO_V110_TA_TIMER_T2);
}
/* ITU-T V.110 Section 7.1.4 */
static void v110_ta_fsm_disconnect(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
switch (event) {
case V110_TA_EV_V24_STATUS_CHG:
break; /* nothing to do */
case V110_TA_EV_TX_FRAME_RTS:
v110_ta_build_frame(ta, (struct osmo_v110_decoded_frame *)data);
break;
case V110_TA_EV_RX_FRAME_IND:
{
const struct osmo_v110_decoded_frame *df = data;
/* 7.1.4.3 The TA at the station that originated the disconnect request will
* recognize reception of S = OFF or the loss of framing signals as a disconnect
* acknowledgement and turn OFF circuits 107 and 109. */
if (v110_df_s_bits_are(df, V110_SX_BIT_OFF)) {
/* circuits 107 and 109 set to off in .onenter() */
v110_ta_fsm_state_chg(V110_TA_ST_IDLE_READY);
}
v110_ta_handle_frame(ta, df);
break;
}
case V110_TA_EV_DESYNC_IND:
case V110_TA_EV_TIMEOUT:
/* circuits 107 and 109 set to off in .onenter() */
v110_ta_fsm_state_chg(V110_TA_ST_IDLE_READY);
break;
default:
OSMO_ASSERT(0);
}
}
/* ITU-T V.110 Section 7.1.5 */
static void v110_ta_fsm_resyncing_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
/* 7.1.5 In the event of loss of frame synchronization, the (local) TA should
* attempt to resynchronize as follows: */
/* a) Place circuit 104 in binary 1 condition (passes from the data mode) */
ts->rx.d_bit_mode = V110_TA_DBIT_M_ALL_ONE;
/* b) Turn OFF status bit X in the transmitted frame */
ts->tx.x_bits = V110_SX_BIT_OFF;
/* guard timeout, see 7.1.5 e) */
OSMO_ASSERT(fi->T == OSMO_V110_TA_TIMER_X1);
}
/* ITU-T V.110 Section 7.1.5 */
static void v110_ta_fsm_resyncing(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct osmo_v110_ta *ta = (struct osmo_v110_ta *)fi->priv;
struct v110_ta_state *ts = &ta->state;
unsigned int v24_flags = ta->state.v24_flags;
switch (event) {
case V110_TA_EV_V24_STATUS_CHG:
break; /* TODO: handle circuit 108 being set to OFF? */
case V110_TA_EV_TX_FRAME_RTS:
v110_ta_build_frame(ta, (struct osmo_v110_decoded_frame *)data);
break;
case V110_TA_EV_SYNC_IND:
/* f) If resynchronization is achieved, the local TA should turn ON status bit X */
ts->tx.x_bits = V110_SX_BIT_ON;
v110_ta_fsm_state_chg(V110_TA_ST_DATA_TRANSFER);
break;
case V110_TA_EV_TIMEOUT:
/* e) If after an interval of X1 seconds the local TA cannot attain synchronization,
* it should send a disconnect request by turning OFF all of the status bits for several
* (at least three) frames with data bits set to binary 0 and then disconnect by turning
* OFF circuit 107 and transferring to the disconnected mode as discussed in 7.1.4.2. */
ts->tx.s_bits = V110_SX_BIT_OFF;
ts->tx.x_bits = V110_SX_BIT_OFF;
ts->tx.d_bit_mode = V110_TA_DBIT_M_ALL_ZERO;
/* TODO: actually Tx those frames (delay state transition) */
V24_FLAGMASK_SET_OFF(v24_flags, OSMO_V110_TA_C_107);
v110_ta_flags_update(ta, v24_flags);
v110_ta_fsm_state_chg(V110_TA_ST_DISCONNECTING);
break;
default:
OSMO_ASSERT(0);
}
}
static int v110_ta_timer_cb(struct osmo_fsm_inst *fi)
{
osmo_fsm_inst_dispatch(fi, V110_TA_EV_TIMEOUT, NULL);
return 0;
}
static const struct osmo_fsm_state v110_ta_states[] = {
[V110_TA_ST_IDLE_READY] = {
.name = "IDLE_READY",
.in_event_mask = S(V110_TA_EV_V24_STATUS_CHG)
| S(V110_TA_EV_TX_FRAME_RTS)
| S(V110_TA_EV_RX_FRAME_IND),
.out_state_mask = S(V110_TA_ST_IDLE_READY)
| S(V110_TA_ST_CON_TA_TO_LINE),
.action = &v110_ta_fsm_idle_ready,
.onenter = &v110_ta_fsm_idle_ready_onenter,
},
[V110_TA_ST_CON_TA_TO_LINE] = {
.name = "CONNECT_TA_TO_LINE",
.in_event_mask = S(V110_TA_EV_V24_STATUS_CHG)
| S(V110_TA_EV_TIMEOUT)
| S(V110_TA_EV_SYNC_IND)
| S(V110_TA_EV_TX_FRAME_RTS)
| S(V110_TA_EV_RX_FRAME_IND),
.out_state_mask = S(V110_TA_ST_DATA_TRANSFER)
| S(V110_TA_ST_IDLE_READY),
.action = &v110_ta_fsm_connect_ta_to_line,
.onenter = &v110_ta_fsm_connect_ta_to_line_onenter,
},
[V110_TA_ST_DATA_TRANSFER] = {
.name = "DATA_TRANSFER",
.in_event_mask = S(V110_TA_EV_V24_STATUS_CHG)
| S(V110_TA_EV_DESYNC_IND)
| S(V110_TA_EV_TX_FRAME_RTS)
| S(V110_TA_EV_RX_FRAME_IND),
.out_state_mask = S(V110_TA_ST_RESYNCING)
| S(V110_TA_ST_DISCONNECTING),
.action = &v110_ta_fsm_data_transfer,
.onenter = &v110_ta_fsm_data_transfer_onenter,
},
[V110_TA_ST_DISCONNECTING] = {
.name = "DISCONNECTING",
.in_event_mask = S(V110_TA_EV_V24_STATUS_CHG)
| S(V110_TA_EV_TIMEOUT)
| S(V110_TA_EV_TX_FRAME_RTS)
| S(V110_TA_EV_RX_FRAME_IND)
| S(V110_TA_EV_DESYNC_IND),
.out_state_mask = S(V110_TA_ST_IDLE_READY),
.action = &v110_ta_fsm_disconnect,
.onenter = &v110_ta_fsm_disconnect_onenter,
},
[V110_TA_ST_RESYNCING] = {
.name = "RESYNCING",
.in_event_mask = S(V110_TA_EV_V24_STATUS_CHG)
| S(V110_TA_EV_TIMEOUT)
| S(V110_TA_EV_TX_FRAME_RTS)
| S(V110_TA_EV_SYNC_IND),
.out_state_mask = S(V110_TA_ST_IDLE_READY)
| S(V110_TA_ST_DATA_TRANSFER),
.action = &v110_ta_fsm_resyncing,
.onenter = &v110_ta_fsm_resyncing_onenter,
},
};
static struct osmo_fsm osmo_v110_ta_fsm = {
.name = "V110-TA",
.states = v110_ta_states,
.num_states = ARRAY_SIZE(v110_ta_states),
.timer_cb = v110_ta_timer_cb,
.log_subsys = DLGLOBAL,
.event_names = v110_ta_fsm_event_names,
};
static __attribute__((constructor)) void on_dso_load(void)
{
OSMO_ASSERT(osmo_fsm_register(&osmo_v110_ta_fsm) == 0);
}
/*! Allocate a V.110 TA (Terminal Adapter) instance.
* \param[in] ctx parent talloc context.
* \param[in] name name of the TA instance.
* \param[in] cfg initial configuration of the TA instance.
* \returns pointer to allocated TA instance; NULL on error. */
struct osmo_v110_ta *osmo_v110_ta_alloc(void *ctx, const char *name,
const struct osmo_v110_ta_cfg *cfg)
{
struct osmo_v110_ta *ta;
OSMO_ASSERT(cfg != NULL);
OSMO_ASSERT(cfg->rx_cb != NULL);
OSMO_ASSERT(cfg->tx_cb != NULL);
/* local (TE-TA) flow control is not implemented */
if (cfg->flow_ctrl.local != OSMO_V110_LOCAL_FLOW_CTRL_NONE) {
LOGP(DLGLOBAL, LOGL_ERROR, "Local (TE-TA) flow control is not implemented\n");
return NULL;
}
ta = talloc_zero(ctx, struct osmo_v110_ta);
if (ta == NULL)
return NULL;
ta->name = talloc_strdup(ta, name);
ta->cfg = talloc_memdup(ta, cfg, sizeof(*cfg));
if (ta->name == NULL || ta->cfg == NULL)
goto exit_free;
ta->Tdefs = talloc_memdup(ta, v110_ta_tdef, sizeof(v110_ta_tdef));
if (ta->Tdefs == NULL)
goto exit_free;
osmo_tdefs_reset(ta->Tdefs); /* apply default values */
ta->fi = osmo_fsm_inst_alloc(&osmo_v110_ta_fsm, ta, ta, LOGL_DEBUG, name);
if (ta->fi == NULL)
goto exit_free;
/* perform a loop transition to init the internal state */
osmo_fsm_inst_state_chg(ta->fi, V110_TA_ST_IDLE_READY, 0, 0);
return ta;
exit_free:
if (ta->fi != NULL)
osmo_fsm_inst_free(ta->fi);
talloc_free(ta);
return NULL;
}
/*! Release memory taken by the given V.110 TA instance.
* \param[in] ta TA instance to be free()d. */
void osmo_v110_ta_free(struct osmo_v110_ta *ta)
{
if (ta == NULL)
return;
if (ta->fi != NULL)
osmo_fsm_inst_free(ta->fi);
talloc_free(ta); /* also free()s name and cfg */
}
/*! Configure a timer of the given V.110 TA instance.
* \param[in] ta TA instance to be configured.
* \param[in] timer a timer to be configured.
* \param[in] val_ms the new timeout value to set (in milliseconds).
* \returns 0 in case of success; negative on error. */
int osmo_v110_ta_set_timer_val_ms(struct osmo_v110_ta *ta,
enum osmo_v110_ta_timer timer,
unsigned long val_ms)
{
return osmo_tdef_set(ta->Tdefs, (int)timer, val_ms, OSMO_TDEF_MS);
}
/*! Feed a [decoded] V.110 frame into the given TA instance.
*
* This function, like its _out counterpart, is intended to be used by the lower layers
* receiving V.110 frames over some medium. The caller of this function is responsible
* for finding the synchronization pattern (if needed), aligning to the frame boundaries,
* and decoding frames using osmo_v110_decode_frame() or osmo_csd_*_decode_frame().
*
* Bits E1/E2/E3 are expected to be set by the caller (if not being transmitted
* over the medium) in accordance with the configured synchronous user rate.
*
* Bits D1..D48 are passed to the bit rate adaption function RA1. The resulting output
* is then passed to the upper layer (application) via the configured .rx_cb(). Though,
* in certain states of the TA's FSM, bits D1..D48 are ignored and the upper layer
* gets a sequence of binary '0' or '1'.
*
* \param[in] ta TA instance to feed the given frame into.
* \param[in] in pointer to a [decoded] V.110 frame.
* \returns 0 in case of success; negative on error. */
int osmo_v110_ta_frame_in(struct osmo_v110_ta *ta, const struct osmo_v110_decoded_frame *in)
{
return osmo_fsm_inst_dispatch(ta->fi, V110_TA_EV_RX_FRAME_IND, (void *)in);
}
/*! Pull a [decoded] V.110 frame out of the given TA instance.
*
* This function, like its _in counterpart, is intended to be used by the lower layers
* transmitting V.110 frames over some medium. The caller of this function is responsible
* for encoding the output frame using osmo_v110_encode_frame() or osmo_csd_*_encode_frame().
*
* Bits E1/E2/E3 are set in accordance with the configured synchronous user rate.
* Bits E4/E5/E6/E7 are unconditionally set to binary '1'.
*
* Bits D1..D48 are set depending on the state of TA's FSM:
*
* - In data transfer mode, the user bits are obtained from the upper layer (application)
* via the configured .tx_cb(), and then passed to the bit rate adaption function RA1,
* which generates bits D1..D48.
* - In other modes, bits D1..D48 are all set to binary '0' or '1'.
*
* \param[in] ta TA instance to pull a frame from.
* \param[out] out where to store a [decoded] V.110 frame.
* \returns 0 in case of success; negative on error. */
int osmo_v110_ta_frame_out(struct osmo_v110_ta *ta, struct osmo_v110_decoded_frame *out)
{
return osmo_fsm_inst_dispatch(ta->fi, V110_TA_EV_TX_FRAME_RTS, (void *)out);
}
/*! Indicate a synchronization establishment event.
*
* This function is intended to be called when the lower layer
* achieves synchronization to the frame clock.
*
* \param[in] ta TA instance to indicate the event to.
* \returns 0 in case of success; negative on error. */
int osmo_v110_ta_sync_ind(struct osmo_v110_ta *ta)
{
return osmo_fsm_inst_dispatch(ta->fi, V110_TA_EV_SYNC_IND, NULL);
}
/*! Indicate a synchronization loss event.
*
* This function is intended to be called when the lower layer
* experiences a loss of synchronization with the frame clock.
*
* \param[in] ta TA instance to indicate the event to.
* \returns 0 in case of success; negative on error. */
int osmo_v110_ta_desync_ind(struct osmo_v110_ta *ta)
{
return osmo_fsm_inst_dispatch(ta->fi, V110_TA_EV_DESYNC_IND, NULL);
}
/*! Get the V.24 status bit-mask of the given TA instance.
* \param[in] ta TA instance to get the circuit bit-mask.
* \returns bitmask of OSMO_V110_TA_C_*. */
unsigned int osmo_v110_ta_get_status(const struct osmo_v110_ta *ta)
{
return ta->state.v24_flags;
}
/*! Set the V.24 status bit-mask of the given TA instance.
* \param[in] ta TA instance to update the circuit state.
* \param[in] status bit-mask of OSMO_V110_TA_C_*.
* \returns 0 on success; negative on error. */
static int v110_ta_set_status(struct osmo_v110_ta *ta, unsigned int status)
{
const unsigned int old_status = ta->state.v24_flags;
int rc = 0;
ta->state.v24_flags = status;
if (status != old_status)
rc = osmo_fsm_inst_dispatch(ta->fi, V110_TA_EV_V24_STATUS_CHG, NULL);
return rc;
}
/*! Get state of a V.24 circuit of the given TA instance.
* \param[in] ta TA instance to get the circuit state.
* \param[in] circuit a V.24 circuit, one of OSMO_V110_TA_C_*.
* \returns circuit state: active (true) or inactive (false). */
bool osmo_v110_ta_get_circuit(const struct osmo_v110_ta *ta,
enum osmo_v110_ta_circuit circuit)
{
return V24_FLAGMASK_IS_ON(ta->state.v24_flags, circuit);
}
/*! Activate/deactivate a V.24 circuit of the given TA instance.
* \param[in] ta TA instance to update the circuit state.
* \param[in] circuit a V.24 circuit, one of OSMO_V110_TA_C_* (DTE->DCE).
* \param[in] active activate (true) or deactivate (false) the circuit.
* \returns 0 on success; negative on error. */
int osmo_v110_ta_set_circuit(struct osmo_v110_ta *ta,
enum osmo_v110_ta_circuit circuit, bool active)
{
unsigned int status = ta->state.v24_flags;
/* permit setting only DTE->DCE circuits */
switch (circuit) {
case OSMO_V110_TA_C_105:
case OSMO_V110_TA_C_108:
case OSMO_V110_TA_C_133:
break;
default:
LOGPFSML(ta->fi, LOGL_ERROR,
"Setting circuit %s is not permitted (wrong direction?)\n",
osmo_v110_ta_circuit_name(circuit));
return -EACCES;
}
if (active)
V24_FLAGMASK_SET_ON(status, circuit);
else
V24_FLAGMASK_SET_OFF(status, circuit);
return v110_ta_set_status(ta, status);
}
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