// SPDX-License-Identifier: GPL-2.0 /* * n_gsm.c GSM 0710 tty multiplexor * Copyright (c) 2009/10 Intel Corporation * Copyright (c) 2022/23 Siemens Mobility GmbH * * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE * * * Outgoing path: * tty -> DLCI fifo -> scheduler -> GSM MUX data queue ---o-> ldisc * control message -> GSM MUX control queue --´ * * Incoming path: * ldisc -> gsm_queue() -o--> tty * `-> gsm_control_response() * * TO DO: * Mostly done: ioctls for setting modes/timing * Partly done: hooks so you can pull off frames to non tty devs * Restart DLCI 0 when it closes ? * Improve the tx engine * Resolve tx side locking by adding a queue_head and routing * all control traffic via it * General tidy/document * Review the locking/move to refcounts more (mux now moved to an * alloc/free model ready) * Use newest tty open/close port helpers and install hooks * What to do about power functions ? * Termios setting and negotiation * Do we need a 'which mux are you' ioctl to correlate mux and tty sets *
*/
/* * Each active data link has a gsm_dlci structure associated which ties * the link layer to an optional tty (if the tty side is open). To avoid * complexity right now these are only ever freed up when the mux is * shut down. * * At the moment we don't free DLCI objects until the mux is torn down * this avoid object life time issues but might be worth review later.
*/
/* Total number of supported devices */ #define GSM_TTY_MINORS 256
/* DLCI 0, 62/63 are special or reserved see gsmtty_open */
#define NUM_DLCI 64
/* * DLCI 0 is used to pass control blocks out of band of the data * flow (and with a higher link priority). One command can be outstanding * at a time and we use this structure to manage them. They are created * and destroyed by the user context, and updated by the receive paths * and timers
*/
struct gsm_control {
u8 cmd; /* Command we are issuing */
u8 *data; /* Data for the command in case we retransmit */ int len; /* Length of block for retransmission */ int done; /* Done flag */ int error; /* Error if any */
};
/* * Each GSM mux we have is represented by this structure. If we are * operating as an ldisc then we use this structure as our ldisc * state. We need to sort out lifetimes and locking with respect * to the gsm mux array. For now we don't free DLCI objects that * have been instantiated until the mux itself is terminated. * * To consider further: tty open versus mux shutdown.
*/
struct gsm_mux { struct tty_struct *tty; /* The tty our ldisc is bound to */
spinlock_t lock; struct mutex mutex; unsignedint num; struct kref ref;
/* Events on the GSM channel */
wait_queue_head_t event;
/* Method for the receiver side */ void (*receive)(struct gsm_mux *gsm, u8 ch);
/* Link Layer */ unsignedint mru; unsignedint mtu; int initiator; /* Did we initiate connection */ bool dead; /* Has the mux been shut down */ struct gsm_dlci *dlci[NUM_DLCI]; int old_c_iflag; /* termios c_iflag value before attach */ bool constipated; /* Asked by remote to shut up */ bool has_devices; /* Devices were registered */
/* Control messages */ struct timer_list kick_timer; /* Kick TX queuing on timeout */ struct timer_list t2_timer; /* Retransmit timer for commands */ int cretries; /* Command retry counter */ struct gsm_control *pending_cmd;/* Our current pending command */
spinlock_t control_lock; /* Protects the pending command */
/* Keep-alive */ struct timer_list ka_timer; /* Keep-alive response timer */
u8 ka_num; /* Keep-alive match pattern */ signedint ka_retries; /* Keep-alive retry counter, -1 if not yet initialized */
/* Configuration */ int adaption; /* 1 or 2 supported */
u8 ftype; /* UI or UIH */ int t1, t2; /* Timers in 1/100th of a sec */ unsignedint t3; /* Power wake-up timer in seconds. */ int n2; /* Retry count */
u8 k; /* Window size */ bool wait_config; /* Wait for configuration by ioctl before DLCI open */
u32 keep_alive; /* Control channel keep-alive in 10ms */
/** * gsm_fcs_add - update FCS * @fcs: Current FCS * @c: Next data * * Update the FCS to include c. Uses the algorithm in the specification * notes.
*/
/** * gsm_fcs_add_block - update FCS for a block * @fcs: Current FCS * @c: buffer of data * @len: length of buffer * * Update the FCS to include c. Uses the algorithm in the specification * notes.
*/
staticinline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
{ while (len--)
fcs = gsm_fcs8[fcs ^ *c++]; return fcs;
}
/** * gsm_read_ea - read a byte into an EA * @val: variable holding value * @c: byte going into the EA * * Processes one byte of an EA. Updates the passed variable * and returns 1 if the EA is now completely read
*/
staticint gsm_read_ea(unsignedint *val, u8 c)
{ /* Add the next 7 bits into the value */
*val <<= 7;
*val |= c >> 1; /* Was this the last byte of the EA 1 = yes*/ return c & EA;
}
/** * gsm_read_ea_val - read a value until EA * @val: variable holding value * @data: buffer of data * @dlen: length of data * * Processes an EA value. Updates the passed variable and * returns the processed data length.
*/ staticunsignedint gsm_read_ea_val(unsignedint *val, const u8 *data, int dlen)
{ unsignedint len = 0;
for (; dlen > 0; dlen--) {
len++; if (gsm_read_ea(val, *data++)) break;
} return len;
}
/** * gsm_encode_modem - encode modem data bits * @dlci: DLCI to encode from * * Returns the correct GSM encoded modem status bits (6 bit field) for * the current status of the DLCI and attached tty object
*/
static u8 gsm_encode_modem(conststruct gsm_dlci *dlci)
{
u8 modembits = 0; /* FC is true flow control not modem bits */ if (dlci->throttled)
modembits |= MDM_FC; if (dlci->modem_tx & TIOCM_DTR)
modembits |= MDM_RTC; if (dlci->modem_tx & TIOCM_RTS)
modembits |= MDM_RTR; if (dlci->modem_tx & TIOCM_RI)
modembits |= MDM_IC; if (dlci->modem_tx & TIOCM_CD || dlci->gsm->initiator)
modembits |= MDM_DV; /* special mappings for passive side to operate as UE */ if (dlci->modem_tx & TIOCM_OUT1)
modembits |= MDM_IC; if (dlci->modem_tx & TIOCM_OUT2)
modembits |= MDM_DV; return modembits;
}
/** * gsm_register_devices - register all tty devices for a given mux index * * @driver: the tty driver that describes the tty devices * @index: the mux number is used to calculate the minor numbers of the * ttys for this mux and may differ from the position in the * mux array.
*/ staticint gsm_register_devices(struct tty_driver *driver, unsignedint index)
{ struct device *dev; int i; unsignedint base;
if (!driver || index >= MAX_MUX) return -EINVAL;
base = index * NUM_DLCI; /* first minor for this index */ for (i = 1; i < NUM_DLCI; i++) { /* Don't register device 0 - this is the control channel * and not a usable tty interface
*/
dev = tty_register_device(gsm_tty_driver, base + i, NULL); if (IS_ERR(dev)) { if (debug & DBG_ERRORS)
pr_info("%s failed to register device minor %u",
__func__, base + i); for (i--; i >= 1; i--)
tty_unregister_device(gsm_tty_driver, base + i); return PTR_ERR(dev);
}
}
return 0;
}
/** * gsm_unregister_devices - unregister all tty devices for a given mux index * * @driver: the tty driver that describes the tty devices * @index: the mux number is used to calculate the minor numbers of the * ttys for this mux and may differ from the position in the * mux array.
*/ staticvoid gsm_unregister_devices(struct tty_driver *driver, unsignedint index)
{ int i; unsignedint base;
if (!driver || index >= MAX_MUX) return;
base = index * NUM_DLCI; /* first minor for this index */ for (i = 1; i < NUM_DLCI; i++) { /* Don't unregister device 0 - this is the control * channel and not a usable tty interface
*/
tty_unregister_device(gsm_tty_driver, base + i);
}
}
/** * gsm_print_packet - display a frame for debug * @hdr: header to print before decode * @addr: address EA from the frame * @cr: C/R bit seen as initiator * @control: control including PF bit * @data: following data bytes * @dlen: length of data * * Displays a packet in human readable format for debugging purposes. The * style is based on amateur radio LAP-B dump display.
*/
staticvoid gsm_print_packet(constchar *hdr, int addr, int cr,
u8 control, const u8 *data, int dlen)
{ if (!(debug & DBG_DUMP)) return; /* Only show user payload frames if debug & DBG_PAYLOAD */ if (!(debug & DBG_PAYLOAD) && addr != 0) if ((control & ~PF) == UI || (control & ~PF) == UIH) return;
pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
switch (control & ~PF) { case SABM:
pr_cont("SABM"); break; case UA:
pr_cont("UA"); break; case DISC:
pr_cont("DISC"); break; case DM:
pr_cont("DM"); break; case UI:
pr_cont("UI"); break; case UIH:
pr_cont("UIH"); break; default: if (!(control & 0x01)) {
pr_cont("I N(S)%d N(R)%d",
(control & 0x0E) >> 1, (control & 0xE0) >> 5);
} elseswitch (control & 0x0F) { case RR:
pr_cont("RR(%d)", (control & 0xE0) >> 5); break; case RNR:
pr_cont("RNR(%d)", (control & 0xE0) >> 5); break; case REJ:
pr_cont("REJ(%d)", (control & 0xE0) >> 5); break; default:
pr_cont("[%02X]", control);
}
}
if (control & PF)
pr_cont("(P)"); else
pr_cont("(F)");
gsm_hex_dump_bytes(NULL, data, dlen);
}
/* * Link level transmission side
*/
/** * gsm_stuff_frame - bytestuff a packet * @input: input buffer * @output: output buffer * @len: length of input * * Expand a buffer by bytestuffing it. The worst case size change * is doubling and the caller is responsible for handing out * suitable sized buffers.
*/
staticint gsm_stuff_frame(const u8 *input, u8 *output, int len)
{ int olen = 0; while (len--) { if (*input == GSM1_SOF || *input == GSM1_ESCAPE
|| (*input & ISO_IEC_646_MASK) == XON
|| (*input & ISO_IEC_646_MASK) == XOFF) {
*output++ = GSM1_ESCAPE;
*output++ = *input++ ^ GSM1_ESCAPE_BITS;
olen++;
} else
*output++ = *input++;
olen++;
} return olen;
}
/** * gsm_send - send a control frame * @gsm: our GSM mux * @addr: address for control frame * @cr: command/response bit seen as initiator * @control: control byte including PF bit * * Format up and transmit a control frame. These should be transmitted * ahead of data when they are needed.
*/ staticint gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
{ struct gsm_msg *msg;
u8 *dp; int ocr; unsignedlong flags;
msg = gsm_data_alloc(gsm, addr, 0, control); if (!msg) return -ENOMEM;
/* toggle C/R coding if not initiator */
ocr = cr ^ (gsm->initiator ? 0 : 1);
/** * gsm_dlci_clear_queues - remove outstanding data for a DLCI * @gsm: mux * @dlci: clear for this DLCI * * Clears the data queues for a given DLCI.
*/ staticvoid gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci)
{ struct gsm_msg *msg, *nmsg; int addr = dlci->addr; unsignedlong flags;
/* Clear data packets in MUX write queue */
spin_lock_irqsave(&gsm->tx_lock, flags);
list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) { if (msg->addr != addr) continue;
gsm->tx_bytes -= msg->len;
list_del(&msg->list);
kfree(msg);
}
spin_unlock_irqrestore(&gsm->tx_lock, flags);
}
/** * gsm_response - send a control response * @gsm: our GSM mux * @addr: address for control frame * @control: control byte including PF bit * * Format up and transmit a link level response frame.
*/
staticinlinevoid gsm_response(struct gsm_mux *gsm, int addr, int control)
{
gsm_send(gsm, addr, 0, control);
}
/** * gsm_command - send a control command * @gsm: our GSM mux * @addr: address for control frame * @control: control byte including PF bit * * Format up and transmit a link level command frame.
*/
staticinlinevoid gsm_command(struct gsm_mux *gsm, int addr, int control)
{
gsm_send(gsm, addr, 1, control);
}
/* Data transmission */
#define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
/** * gsm_data_alloc - allocate data frame * @gsm: GSM mux * @addr: DLCI address * @len: length excluding header and FCS * @ctrl: control byte * * Allocate a new data buffer for sending frames with data. Space is left * at the front for header bytes but that is treated as an implementation * detail and not for the high level code to use
*/
/** * gsm_send_packet - sends a single packet * @gsm: GSM Mux * @msg: packet to send * * The given packet is encoded and sent out. No memory is freed. * The caller must hold the gsm tx lock.
*/ staticint gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
{ int len, ret;
ret = gsmld_output(gsm, gsm->txframe, len); if (ret <= 0) return ret; /* FIXME: Can eliminate one SOF in many more cases */
gsm->tx_bytes -= msg->len;
return 0;
}
/** * gsm_is_flow_ctrl_msg - checks if flow control message * @msg: message to check * * Returns true if the given message is a flow control command of the * control channel. False is returned in any other case.
*/ staticbool gsm_is_flow_ctrl_msg(struct gsm_msg *msg)
{ unsignedint cmd;
if (msg->addr > 0) returnfalse;
switch (msg->ctrl & ~PF) { case UI: case UIH:
cmd = 0; if (gsm_read_ea_val(&cmd, msg->data + 2, msg->len - 2) < 1) break; switch (cmd & ~PF) { case CMD_FCOFF: case CMD_FCON: returntrue;
} break;
}
returnfalse;
}
/** * gsm_data_kick - poke the queue * @gsm: GSM Mux * * The tty device has called us to indicate that room has appeared in * the transmit queue. Ram more data into the pipe if we have any. * If we have been flow-stopped by a CMD_FCOFF, then we can only * send messages on DLCI0 until CMD_FCON. The caller must hold * the gsm tx lock.
*/ staticint gsm_data_kick(struct gsm_mux *gsm)
{ struct gsm_msg *msg, *nmsg; struct gsm_dlci *dlci; int ret;
clear_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
/* Serialize control messages and control channel messages first */
list_for_each_entry_safe(msg, nmsg, &gsm->tx_ctrl_list, list) { if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg)) continue;
ret = gsm_send_packet(gsm, msg); switch (ret) { case -ENOSPC: return -ENOSPC; case -ENODEV: /* ldisc not open */
gsm->tx_bytes -= msg->len;
list_del(&msg->list);
kfree(msg); continue; default: if (ret >= 0) {
list_del(&msg->list);
kfree(msg);
} break;
}
}
if (gsm->constipated) return -EAGAIN;
/* Serialize other channels */ if (list_empty(&gsm->tx_data_list)) return 0;
list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
dlci = gsm->dlci[msg->addr]; /* Send only messages for DLCIs with valid state */ if (dlci->state != DLCI_OPEN) {
gsm->tx_bytes -= msg->len;
list_del(&msg->list);
kfree(msg); continue;
}
ret = gsm_send_packet(gsm, msg); switch (ret) { case -ENOSPC: return -ENOSPC; case -ENODEV: /* ldisc not open */
gsm->tx_bytes -= msg->len;
list_del(&msg->list);
kfree(msg); continue; default: if (ret >= 0) {
list_del(&msg->list);
kfree(msg);
} break;
}
}
return 1;
}
/** * __gsm_data_queue - queue a UI or UIH frame * @dlci: DLCI sending the data * @msg: message queued * * Add data to the transmit queue and try and get stuff moving * out of the mux tty if not already doing so. The Caller must hold * the gsm tx lock.
*/
/** * gsm_data_queue - queue a UI or UIH frame * @dlci: DLCI sending the data * @msg: message queued * * Add data to the transmit queue and try and get stuff moving * out of the mux tty if not already doing so. Take the * the gsm tx lock and dlci lock.
*/
/** * gsm_dlci_data_output - try and push data out of a DLCI * @gsm: mux * @dlci: the DLCI to pull data from * * Pull data from a DLCI and send it into the transmit queue if there * is data. Keep to the MRU of the mux. This path handles the usual tty * interface which is a byte stream with optional modem data. * * Caller must hold the tx_lock of the mux.
*/
/* Notify upper layer about available send space. */
tty_port_tty_wakeup(&dlci->port);
__gsm_data_queue(dlci, msg); /* Bytes of data we used up */ return size;
}
/** * gsm_dlci_data_output_framed - try and push data out of a DLCI * @gsm: mux * @dlci: the DLCI to pull data from * * Pull data from a DLCI and send it into the transmit queue if there * is data. Keep to the MRU of the mux. This path handles framed data * queued as skbuffs to the DLCI. * * Caller must hold the tx_lock of the mux.
*/
staticint gsm_dlci_data_output_framed(struct gsm_mux *gsm, struct gsm_dlci *dlci)
{ struct gsm_msg *msg;
u8 *dp; int len, size; int last = 0, first = 0; int overhead = 0;
/* One byte per frame is used for B/F flags */ if (dlci->adaption == 4)
overhead = 1;
/* dlci->skb is locked by tx_lock */ if (dlci->skb == NULL) {
dlci->skb = skb_dequeue_tail(&dlci->skb_list); if (dlci->skb == NULL) return 0;
first = 1;
}
len = dlci->skb->len + overhead;
/* MTU/MRU count only the data bits */ if (len > dlci->mtu) { if (dlci->adaption == 3) { /* Over long frame, bin it */
dev_kfree_skb_any(dlci->skb);
dlci->skb = NULL; return 0;
}
len = dlci->mtu;
} else
last = 1;
if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */ /* Flag byte to carry the start/end info */
*dp++ = last << 7 | first << 6 | 1; /* EA */
len--;
}
memcpy(dp, dlci->skb->data, len);
skb_pull(dlci->skb, len);
__gsm_data_queue(dlci, msg); if (last) {
dev_kfree_skb_any(dlci->skb);
dlci->skb = NULL;
} return size;
}
/** * gsm_dlci_modem_output - try and push modem status out of a DLCI * @gsm: mux * @dlci: the DLCI to pull modem status from * @brk: break signal * * Push an empty frame in to the transmit queue to update the modem status * bits and to transmit an optional break. * * Caller must hold the tx_lock of the mux.
*/
/** * gsm_dlci_data_sweep - look for data to send * @gsm: the GSM mux * * Sweep the GSM mux channels in priority order looking for ones with * data to send. We could do with optimising this scan a bit. We aim * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit * TX_THRESH_LO we get called again * * FIXME: We should round robin between groups and in theory you can * renegotiate DLCI priorities with optional stuff. Needs optimising.
*/
staticint gsm_dlci_data_sweep(struct gsm_mux *gsm)
{ /* Priority ordering: We should do priority with RR of the groups */ int i, len, ret = 0; bool sent; struct gsm_dlci *dlci;
while (gsm->tx_bytes < TX_THRESH_HI) { for (sent = false, i = 1; i < NUM_DLCI; i++) {
dlci = gsm->dlci[i]; /* skip unused or blocked channel */ if (!dlci || dlci->constipated) continue; /* skip channels with invalid state */ if (dlci->state != DLCI_OPEN) continue; /* count the sent data per adaption */ if (dlci->adaption < 3 && !dlci->net)
len = gsm_dlci_data_output(gsm, dlci); else
len = gsm_dlci_data_output_framed(gsm, dlci); /* on error exit */ if (len < 0) return ret; if (len > 0) {
ret++;
sent = true; /* The lower DLCs can starve the higher DLCs! */ break;
} /* try next */
} if (!sent) break;
}
return ret;
}
/** * gsm_dlci_data_kick - transmit if possible * @dlci: DLCI to kick * * Transmit data from this DLCI if the queue is empty. We can't rely on * a tty wakeup except when we filled the pipe so we need to fire off * new data ourselves in other cases.
*/
staticvoid gsm_dlci_data_kick(struct gsm_dlci *dlci)
{ unsignedlong flags; int sweep;
if (dlci->constipated) return;
spin_lock_irqsave(&dlci->gsm->tx_lock, flags); /* If we have nothing running then we need to fire up */
sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO); if (dlci->gsm->tx_bytes == 0) { if (dlci->net)
gsm_dlci_data_output_framed(dlci->gsm, dlci); else
gsm_dlci_data_output(dlci->gsm, dlci);
} if (sweep)
gsm_dlci_data_sweep(dlci->gsm);
spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
}
/* * Control message processing
*/
/** * gsm_control_command - send a command frame to a control * @gsm: gsm channel * @cmd: the command to use * @data: data to follow encoded info * @dlen: length of data * * Encode up and queue a UI/UIH frame containing our command.
*/ staticint gsm_control_command(struct gsm_mux *gsm, int cmd, const u8 *data, int dlen)
{ struct gsm_msg *msg; struct gsm_dlci *dlci = gsm->dlci[0];
/** * gsm_control_reply - send a response frame to a control * @gsm: gsm channel * @cmd: the command to use * @data: data to follow encoded info * @dlen: length of data * * Encode up and queue a UI/UIH frame containing our response.
*/
staticvoid gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data, int dlen)
{ struct gsm_msg *msg; struct gsm_dlci *dlci = gsm->dlci[0];
/** * gsm_process_modem - process received modem status * @tty: virtual tty bound to the DLCI * @dlci: DLCI to affect * @modem: modem bits (full EA) * @slen: number of signal octets * * Used when a modem control message or line state inline in adaption * layer 2 is processed. Sort out the local modem state and throttles
*/
staticvoid gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
u32 modem, int slen)
{ int mlines = 0;
u8 brk = 0; int fc;
/* The modem status command can either contain one octet (V.24 signals) * or two octets (V.24 signals + break signals). This is specified in * section 5.4.6.3.7 of the 07.10 mux spec.
*/
if (n1 < MIN_MTU) { if (debug & DBG_ERRORS)
pr_info("%s N1 out of range in PN\n", __func__); return -EINVAL;
}
switch (i) { case 0x00:
ftype = UIH; break; case 0x01:
ftype = UI; break; case 0x02: /* I frames are not supported */ if (debug & DBG_ERRORS)
pr_info("%s unsupported I frame request in PN\n",
__func__);
gsm->unsupported++; return -EINVAL; default: if (debug & DBG_ERRORS)
pr_info("%s i out of range in PN\n", __func__); return -EINVAL;
}
if (!cr && gsm->initiator) { if (adaption != dlci->adaption) { if (debug & DBG_ERRORS)
pr_info("%s invalid adaption %d in PN\n",
__func__, adaption); return -EINVAL;
} if (prio != dlci->prio) { if (debug & DBG_ERRORS)
pr_info("%s invalid priority %d in PN",
__func__, prio); return -EINVAL;
} if (n1 > gsm->mru || n1 > dlci->mtu) { /* We requested a frame size but the other party wants * to send larger frames. The standard allows only a * smaller response value than requested (5.4.6.3.1).
*/ if (debug & DBG_ERRORS)
pr_info("%s invalid N1 %d in PN\n", __func__,
n1); return -EINVAL;
}
dlci->mtu = n1; if (ftype != dlci->ftype) { if (debug & DBG_ERRORS)
pr_info("%s invalid i %d in PN\n", __func__, i); return -EINVAL;
} if (ftype != UI && ftype != UIH && k > dlci->k) { if (debug & DBG_ERRORS)
pr_info("%s invalid k %d in PN\n", __func__, k); return -EINVAL;
}
dlci->k = k;
} elseif (cr && !gsm->initiator) { /* Only convergence layer type 1 and 2 are supported. */ if (adaption != 1 && adaption != 2) { if (debug & DBG_ERRORS)
pr_info("%s invalid adaption %d in PN\n",
__func__, adaption); return -EINVAL;
}
dlci->adaption = adaption; if (n1 > gsm->mru) { /* Propose a smaller value */
dlci->mtu = gsm->mru;
} elseif (n1 > MAX_MTU) { /* Propose a smaller value */
dlci->mtu = MAX_MTU;
} else {
dlci->mtu = n1;
}
dlci->prio = prio;
dlci->ftype = ftype;
dlci->k = k;
} else { return -EINVAL;
}
return 0;
}
/** * gsm_control_modem - modem status received * @gsm: GSM channel * @data: data following command * @clen: command length * * We have received a modem status control message. This is used by * the GSM mux protocol to pass virtual modem line status and optionally * to indicate break signals. Unpack it, convert to Linux representation * and if need be stuff a break message down the tty.
*/
staticvoid gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
{ unsignedint addr = 0; unsignedint modem = 0; struct gsm_dlci *dlci; int len = clen; int cl = clen; const u8 *dp = data; struct tty_struct *tty;
len = gsm_read_ea_val(&addr, data, cl); if (len < 1) return;
/** * gsm_control_negotiation - parameter negotiation received * @gsm: GSM channel * @cr: command/response flag * @data: data following command * @dlen: data length * * We have received a parameter negotiation message. This is used by * the GSM mux protocol to configure protocol parameters for a new DLCI.
*/ staticvoid gsm_control_negotiation(struct gsm_mux *gsm, unsignedint cr, const u8 *data, unsignedint dlen)
{ unsignedint addr; struct gsm_dlci_param_bits pn_reply; struct gsm_dlci *dlci; struct gsm_dlci_param_bits *params;
if (dlen < sizeof(struct gsm_dlci_param_bits)) {
gsm->open_error++; return;
}
/* Too late for parameter negotiation? */ if ((!cr && dlci->state == DLCI_OPENING) || dlci->state == DLCI_OPEN) {
gsm->open_error++; return;
}
/* Process the received parameters */ if (gsm_process_negotiation(gsm, addr, cr, params) != 0) { /* Negotiation failed. Close the link. */ if (debug & DBG_ERRORS)
pr_info("%s PN failed\n", __func__);
gsm->open_error++;
gsm_dlci_close(dlci); return;
}
if (cr) { /* Reply command with accepted parameters. */ if (gsm_encode_params(dlci, &pn_reply) == 0)
gsm_control_reply(gsm, CMD_PN, (const u8 *)&pn_reply, sizeof(pn_reply)); elseif (debug & DBG_ERRORS)
pr_info("%s PN invalid\n", __func__);
} elseif (dlci->state == DLCI_CONFIGURE) { /* Proceed with link setup by sending SABM before UA */
dlci->state = DLCI_OPENING;
gsm_command(gsm, dlci->addr, SABM|PF);
mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
} else { if (debug & DBG_ERRORS)
pr_info("%s PN in invalid state\n", __func__);
gsm->open_error++;
}
}
/** * gsm_control_rls - remote line status * @gsm: GSM channel * @data: data bytes * @clen: data length * * The modem sends us a two byte message on the control channel whenever * it wishes to send us an error state from the virtual link. Stuff * this into the uplink tty if present
*/
staticvoid gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
{ struct tty_port *port; unsignedint addr = 0;
u8 bits; int len = clen; const u8 *dp = data;
while (gsm_read_ea(&addr, *dp++) == 0) {
len--; if (len == 0) return;
} /* Must be at least one byte following ea */
len--; if (len <= 0) return;
addr >>= 1; /* Closed port, or invalid ? */ if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL) return; /* No error ? */
bits = *dp; if ((bits & 1) == 0) return;
port = &gsm->dlci[addr]->port;
if (bits & 2)
tty_insert_flip_char(port, 0, TTY_OVERRUN); if (bits & 4)
tty_insert_flip_char(port, 0, TTY_PARITY); if (bits & 8)
tty_insert_flip_char(port, 0, TTY_FRAME);
/** * gsm_control_message - DLCI 0 control processing * @gsm: our GSM mux * @command: the command EA * @data: data beyond the command/length EAs * @clen: length * * Input processor for control messages from the other end of the link. * Processes the incoming request and queues a response frame or an * NSC response if not supported
*/
switch (command) { case CMD_CLD: { struct gsm_dlci *dlci = gsm->dlci[0]; /* Modem wishes to close down */ if (dlci) {
dlci->dead = true;
gsm->dead = true;
gsm_dlci_begin_close(dlci);
}
} break; case CMD_TEST: /* Modem wishes to test, reply with the data */
gsm_control_reply(gsm, CMD_TEST, data, clen); break; case CMD_FCON: /* Modem can accept data again */
gsm->constipated = false;
gsm_control_reply(gsm, CMD_FCON, NULL, 0); /* Kick the link in case it is idling */
gsmld_write_trigger(gsm); break; case CMD_FCOFF: /* Modem wants us to STFU */
gsm->constipated = true;
gsm_control_reply(gsm, CMD_FCOFF, NULL, 0); break; case CMD_MSC: /* Out of band modem line change indicator for a DLCI */
gsm_control_modem(gsm, data, clen); break; case CMD_RLS: /* Out of band error reception for a DLCI */
gsm_control_rls(gsm, data, clen); break; case CMD_PSC: /* Modem wishes to enter power saving state */
gsm_control_reply(gsm, CMD_PSC, NULL, 0); break; /* Optional commands */ case CMD_PN: /* Modem sends a parameter negotiation command */
gsm_control_negotiation(gsm, 1, data, clen); break; /* Optional unsupported commands */ case CMD_RPN: /* Remote port negotiation */ case CMD_SNC: /* Service negotiation command */
gsm->unsupported++;
fallthrough; default: /* Reply to bad commands with an NSC */
buf[0] = command;
gsm_control_reply(gsm, CMD_NSC, buf, 1); break;
}
}
/** * gsm_control_response - process a response to our control * @gsm: our GSM mux * @command: the command (response) EA * @data: data beyond the command/length EA * @clen: length * * Process a response to an outstanding command. We only allow a single * control message in flight so this is fairly easy. All the clean up * is done by the caller, we just update the fields, flag it as done * and return
*/
ctrl = gsm->pending_cmd;
dlci = gsm->dlci[0];
command |= 1; /* Does the reply match our command */ if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) { /* Our command was replied to, kill the retry timer */
timer_delete(&gsm->t2_timer);
gsm->pending_cmd = NULL; /* Rejected by the other end */ if (command == CMD_NSC)
ctrl->error = -EOPNOTSUPP;
ctrl->done = 1;
wake_up(&gsm->event); /* Or did we receive the PN response to our PN command */
} elseif (command == CMD_PN) {
gsm_control_negotiation(gsm, 0, data, clen); /* Or did we receive the TEST response to our TEST command */
} elseif (command == CMD_TEST && clen == 1 && *data == gsm->ka_num) {
gsm->ka_retries = -1; /* trigger new keep-alive message */ if (dlci && !dlci->dead)
mod_timer(&gsm->ka_timer, jiffies + gsm->keep_alive * HZ / 100);
}
spin_unlock_irqrestore(&gsm->control_lock, flags);
}
/** * gsm_control_keep_alive - check timeout or start keep-alive * @t: timer contained in our gsm object * * Called off the keep-alive timer expiry signaling that our link * partner is not responding anymore. Link will be closed. * This is also called to startup our timer.
*/
spin_lock_irqsave(&gsm->control_lock, flags); if (gsm->ka_num && gsm->ka_retries == 0) { /* Keep-alive expired -> close the link */ if (debug & DBG_ERRORS)
pr_debug("%s keep-alive timed out\n", __func__);
spin_unlock_irqrestore(&gsm->control_lock, flags); if (gsm->dlci[0])
gsm_dlci_begin_close(gsm->dlci[0]); return;
} elseif (gsm->keep_alive && gsm->dlci[0] && !gsm->dlci[0]->dead) { if (gsm->ka_retries > 0) { /* T2 expired for keep-alive -> resend */
gsm->ka_retries--;
} else { /* Start keep-alive timer */
gsm->ka_num++; if (!gsm->ka_num)
gsm->ka_num++;
gsm->ka_retries = (signedint)gsm->n2;
}
gsm_control_command(gsm, CMD_TEST, &gsm->ka_num, sizeof(gsm->ka_num));
mod_timer(&gsm->ka_timer,
jiffies + gsm->t2 * HZ / 100);
}
spin_unlock_irqrestore(&gsm->control_lock, flags);
}
/** * gsm_control_transmit - send control packet * @gsm: gsm mux * @ctrl: frame to send * * Send out a pending control command (called under control lock)
*/
/** * gsm_control_retransmit - retransmit a control frame * @t: timer contained in our gsm object * * Called off the T2 timer expiry in order to retransmit control frames * that have been lost in the system somewhere. The control_lock protects * us from colliding with another sender or a receive completion event. * In that situation the timer may still occur in a small window but * gsm->pending_cmd will be NULL and we just let the timer expire.
*/
/** * gsm_control_send - send a control frame on DLCI 0 * @gsm: the GSM channel * @command: command to send including CR bit * @data: bytes of data (must be kmalloced) * @clen: length of the block to send * * Queue and dispatch a control command. Only one command can be * active at a time. In theory more can be outstanding but the matching * gets really complicated so for now stick to one outstanding.
*/
/** * gsm_control_wait - wait for a control to finish * @gsm: GSM mux * @control: control we are waiting on * * Waits for the control to complete or time out. Frees any used * resources and returns 0 for success, or an error if the remote * rejected or ignored the request.
*/
/** * gsm_dlci_close - a DLCI has closed * @dlci: DLCI that closed * * Perform processing when moving a DLCI into closed state. If there * is an attached tty this is hung up
*/
staticvoid gsm_dlci_close(struct gsm_dlci *dlci)
{
timer_delete(&dlci->t1); if (debug & DBG_ERRORS)
pr_debug("DLCI %d goes closed.\n", dlci->addr);
dlci->state = DLCI_CLOSED; /* Prevent us from sending data before the link is up again */
dlci->constipated = true; if (dlci->addr != 0) {
tty_port_tty_hangup(&dlci->port, false);
gsm_dlci_clear_queues(dlci->gsm, dlci); /* Ensure that gsmtty_open() can return. */
tty_port_set_initialized(&dlci->port, false);
wake_up_interruptible(&dlci->port.open_wait);
} else {
timer_delete(&dlci->gsm->ka_timer);
dlci->gsm->dead = true;
} /* A DLCI 0 close is a MUX termination so we need to kick that
back to userspace somehow */
gsm_dlci_data_kick(dlci);
wake_up_all(&dlci->gsm->event);
}
/** * gsm_dlci_open - a DLCI has opened * @dlci: DLCI that opened * * Perform processing when moving a DLCI into open state.
*/
/* Note that SABM UA .. SABM UA first UA lost can mean that we go
open -> open */
timer_delete(&dlci->t1); /* This will let a tty open continue */
dlci->state = DLCI_OPEN;
dlci->constipated = false; if (debug & DBG_ERRORS)
pr_debug("DLCI %d goes open.\n", dlci->addr); /* Send current modem state */ if (dlci->addr) {
gsm_modem_send_initial_msc(dlci);
} else { /* Start keep-alive control */
gsm->ka_num = 0;
gsm->ka_retries = -1;
mod_timer(&gsm->ka_timer,
jiffies + gsm->keep_alive * HZ / 100);
}
gsm_dlci_data_kick(dlci);
wake_up(&dlci->gsm->event);
}
/** * gsm_dlci_negotiate - start parameter negotiation * @dlci: DLCI to open * * Starts the parameter negotiation for the new DLCI. This needs to be done * before the DLCI initialized the channel via SABM.
*/ staticint gsm_dlci_negotiate(struct gsm_dlci *dlci)
{ struct gsm_mux *gsm = dlci->gsm; struct gsm_dlci_param_bits params; int ret;
ret = gsm_encode_params(dlci, ¶ms); if (ret != 0) return ret;
/* We cannot asynchronous wait for the command response with * gsm_command() and gsm_control_wait() at this point.
*/
ret = gsm_control_command(gsm, CMD_PN, (const u8 *)¶ms, sizeof(params));
return ret;
}
/** * gsm_dlci_t1 - T1 timer expiry * @t: timer contained in the DLCI that opened * * The T1 timer handles retransmits of control frames (essentially of * SABM and DISC). We resend the command until the retry count runs out * in which case an opening port goes back to closed and a closing port * is simply put into closed state (any further frames from the other * end will get a DM response) * * Some control dlci can stay in ADM mode with other dlci working just * fine. In that case we can just keep the control dlci open after the * DLCI_OPENING receives DM.
*/
/** * gsm_dlci_begin_open - start channel open procedure * @dlci: DLCI to open * * Commence opening a DLCI from the Linux side. We issue SABM messages * to the modem which should then reply with a UA or ADM, at which point * we will move into open state. Opening is done asynchronously with retry * running off timers and the responses. * Parameter negotiation is performed before SABM if required.
*/
if (dlci->addr != 0) { if (gsm->adaption != 1 || gsm->adaption != dlci->adaption)
need_pn = true; if (dlci->prio != (roundup(dlci->addr + 1, 8) - 1))
need_pn = true; if (gsm->ftype != dlci->ftype)
need_pn = true;
}
switch (dlci->state) { case DLCI_CLOSED: case DLCI_WAITING_CONFIG: case DLCI_CLOSING:
dlci->retries = gsm->n2; if (!need_pn) {
dlci->state = DLCI_OPENING; if (!dlci->addr || !gsm->dlci[0] ||
gsm->dlci[0]->state != DLCI_OPENING)
gsm_command(gsm, dlci->addr, SABM|PF);
} else { /* Configure DLCI before setup */
dlci->state = DLCI_CONFIGURE; if (gsm_dlci_negotiate(dlci) != 0) {
gsm_dlci_close(dlci); return;
}
}
mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); break; default: break;
}
}
/** * gsm_dlci_set_opening - change state to opening * @dlci: DLCI to open * * Change internal state to wait for DLCI open from initiator side. * We set off timers and responses upon reception of an SABM.
*/ staticvoid gsm_dlci_set_opening(struct gsm_dlci *dlci)
{ switch (dlci->state) { case DLCI_CLOSED: case DLCI_WAITING_CONFIG: case DLCI_CLOSING:
dlci->state = DLCI_OPENING; break; default: break;
}
}
/** * gsm_dlci_set_wait_config - wait for channel configuration * @dlci: DLCI to configure * * Wait for a DLCI configuration from the application.
*/ staticvoid gsm_dlci_set_wait_config(struct gsm_dlci *dlci)
{ switch (dlci->state) { case DLCI_CLOSED: case DLCI_CLOSING:
dlci->state = DLCI_WAITING_CONFIG; break; default: break;
}
}
/** * gsm_dlci_begin_close - start channel open procedure * @dlci: DLCI to open * * Commence closing a DLCI from the Linux side. We issue DISC messages * to the modem which should then reply with a UA, at which point we * will move into closed state. Closing is done asynchronously with retry * off timers. We may also receive a DM reply from the other end which * indicates the channel was already closed.
*/
/** * gsm_dlci_data - data arrived * @dlci: channel * @data: block of bytes received * @clen: length of received block * * A UI or UIH frame has arrived which contains data for a channel * other than the control channel. If the relevant virtual tty is * open we shovel the bits down it, if not we drop them.
*/
if (debug & DBG_TTY)
pr_debug("%d bytes for tty\n", clen); switch (dlci->adaption) { /* Unsupported types */ case 4: /* Packetised interruptible data */ break; case 3: /* Packetised uininterruptible voice/data */ break; case 2: /* Asynchronous serial with line state in each frame */
len = gsm_read_ea_val(&modem, data, clen); if (len < 1) return;
tty = tty_port_tty_get(port); if (tty) {
gsm_process_modem(tty, dlci, modem, len);
tty_wakeup(tty);
tty_kref_put(tty);
} /* Skip processed modem data */
data += len;
clen -= len;
fallthrough; case 1: /* Line state will go via DLCI 0 controls only */ default:
tty_insert_flip_string(port, data, clen);
tty_flip_buffer_push(port);
}
}
/** * gsm_dlci_command - data arrived on control channel * @dlci: channel * @data: block of bytes received * @len: length of received block * * A UI or UIH frame has arrived which contains data for DLCI 0 the * control channel. This should contain a command EA followed by * control data bytes. The command EA contains a command/response bit * and we divide up the work accordingly.
*/
staticvoid gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
{ /* See what command is involved */ unsignedint command = 0; unsignedint clen = 0; unsignedint dlen;
/* read the command */
dlen = gsm_read_ea_val(&command, data, len);
len -= dlen;
data += dlen;
/* read any control data */
dlen = gsm_read_ea_val(&clen, data, len);
len -= dlen;
data += dlen;
/** * gsm_kick_timer - transmit if possible * @t: timer contained in our gsm object * * Transmit data from DLCIs if the queue is empty. We can't rely on * a tty wakeup except when we filled the pipe so we need to fire off * new data ourselves in other cases.
*/ staticvoid gsm_kick_timer(struct timer_list *t)
{ struct gsm_mux *gsm = timer_container_of(gsm, t, kick_timer); unsignedlong flags; int sent = 0;
spin_lock_irqsave(&gsm->tx_lock, flags); /* If we have nothing running then we need to fire up */ if (gsm->tx_bytes < TX_THRESH_LO)
sent = gsm_dlci_data_sweep(gsm);
spin_unlock_irqrestore(&gsm->tx_lock, flags);
/** * gsm_dlci_config - configure DLCI from configuration * @dlci: DLCI to configure * @dc: DLCI configuration * @open: open DLCI after configuration?
*/ staticint gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, int open)
{ struct gsm_mux *gsm; bool need_restart = false; bool need_open = false; unsignedint i;
/* * Check that userspace doesn't put stuff in here to prevent breakages * in the future.
*/ for (i = 0; i < ARRAY_SIZE(dc->reserved); i++) if (dc->reserved[i]) return -EINVAL;
if (!dlci) return -EINVAL;
gsm = dlci->gsm;
/* Stuff we don't support yet - I frame transport */ if (dc->adaption != 1 && dc->adaption != 2) return -EOPNOTSUPP; if (dc->mtu > MAX_MTU || dc->mtu < MIN_MTU || dc->mtu > gsm->mru) return -EINVAL; if (dc->priority >= 64) return -EINVAL; if (dc->i == 0 || dc->i > 2) /* UIH and UI only */ return -EINVAL; if (dc->k > 7) return -EINVAL; if (dc->flags & ~GSM_FL_RESTART) /* allow future extensions */ return -EINVAL;
/* * See what is needed for reconfiguration
*/ /* Framing fields */ if (dc->adaption != dlci->adaption)
need_restart = true; if (dc->mtu != dlci->mtu)
need_restart = true; if (dc->i != dlci->ftype)
need_restart = true; /* Requires care */ if (dc->priority != dlci->prio)
need_restart = true; if (dc->flags & GSM_FL_RESTART)
need_restart = true;
/* * Close down what is needed, restart and initiate the new * configuration.
*/ if (need_restart) {
gsm_dlci_begin_close(dlci);
wait_event_interruptible(gsm->event, dlci->state == DLCI_CLOSED); if (signal_pending(current)) return -EINTR;
} /* * Setup the new configuration values
*/
dlci->adaption = (int)dc->adaption;
if (dc->mtu)
dlci->mtu = (unsignedint)dc->mtu; else
dlci->mtu = gsm->mtu;
if (dc->k)
dlci->k = (u8)dc->k; else
dlci->k = gsm->k;
if (need_open) { if (gsm->initiator)
gsm_dlci_begin_open(dlci); else
gsm_dlci_set_opening(dlci);
}
return 0;
}
/* * Allocate/Free DLCI channels
*/
/** * gsm_dlci_alloc - allocate a DLCI * @gsm: GSM mux * @addr: address of the DLCI * * Allocate and install a new DLCI object into the GSM mux. * * FIXME: review locking races
*/
/** * gsm_dlci_release - release DLCI * @dlci: DLCI to destroy * * Release a DLCI. Actual free is deferred until either * mux is closed or tty is closed - whichever is last. * * Can sleep.
*/ staticvoid gsm_dlci_release(struct gsm_dlci *dlci)
{ struct tty_struct *tty = tty_port_tty_get(&dlci->port); if (tty) {
mutex_lock(&dlci->mutex);
gsm_destroy_network(dlci);
mutex_unlock(&dlci->mutex);
/* We cannot use tty_hangup() because in tty_kref_put() the tty * driver assumes that the hangup queue is free and reuses it to * queue release_one_tty() -> NULL pointer panic in * process_one_work().
*/
tty_vhangup(tty);
/** * gsm_queue - a GSM frame is ready to process * @gsm: pointer to our gsm mux * * At this point in time a frame has arrived and been demangled from * the line encoding. All the differences between the encodings have * been handled below us and the frame is unpacked into the structures. * The fcs holds the header FCS but any data FCS must be added here.
*/
switch (gsm->control) { case SABM|PF: if (cr == 1) {
gsm->open_error++; goto invalid;
} if (dlci == NULL)
dlci = gsm_dlci_alloc(gsm, address); if (dlci == NULL) {
gsm->open_error++; return;
} if (dlci->dead)
gsm_response(gsm, address, DM|PF); else {
gsm_response(gsm, address, UA|PF);
gsm_dlci_open(dlci);
} break; case DISC|PF: if (cr == 1) goto invalid; if (dlci == NULL || dlci->state == DLCI_CLOSED) {
gsm_response(gsm, address, DM|PF); return;
} /* Real close complete */
gsm_response(gsm, address, UA|PF);
gsm_dlci_close(dlci); break; case UA|PF: if (cr == 0 || dlci == NULL) break; switch (dlci->state) { case DLCI_CLOSING:
gsm_dlci_close(dlci); break; case DLCI_OPENING:
gsm_dlci_open(dlci); break; default:
pr_debug("%s: unhandled state: %d\n", __func__,
dlci->state); break;
} break; case DM: /* DM can be valid unsolicited */ case DM|PF: if (cr) goto invalid; if (dlci == NULL) return;
gsm_dlci_close(dlci); break; case UI: case UI|PF: case UIH: case UIH|PF: if (dlci == NULL || dlci->state != DLCI_OPEN) {
gsm_response(gsm, address, DM|PF); return;
}
dlci->data(dlci, gsm->buf, gsm->len); break; default: goto invalid;
} return;
invalid:
gsm->malformed++; return;
}
/** * gsm0_receive_state_check_and_fix - check and correct receive state * @gsm: gsm data for this ldisc instance * * Ensures that the current receive state is valid for basic option mode.
*/
staticvoid gsm0_receive_state_check_and_fix(struct gsm_mux *gsm)
{ switch (gsm->state) { case GSM_SEARCH: case GSM0_ADDRESS: case GSM0_CONTROL: case GSM0_LEN0: case GSM0_LEN1: case GSM0_DATA: case GSM0_FCS: case GSM0_SSOF: break; default:
gsm->state = GSM_SEARCH; break;
}
}
/** * gsm0_receive - perform processing for non-transparency * @gsm: gsm data for this ldisc instance * @c: character * * Receive bytes in gsm mode 0
*/
staticvoid gsm0_receive(struct gsm_mux *gsm, u8 c)
{ unsignedint len;
gsm0_receive_state_check_and_fix(gsm); switch (gsm->state) { case GSM_SEARCH: /* SOF marker */ if (c == GSM0_SOF) {
gsm->state = GSM0_ADDRESS;
gsm->address = 0;
gsm->len = 0;
gsm->fcs = INIT_FCS;
} break; case GSM0_ADDRESS: /* Address EA */
gsm->fcs = gsm_fcs_add(gsm->fcs, c); if (gsm_read_ea(&gsm->address, c))
gsm->state = GSM0_CONTROL; break; case GSM0_CONTROL: /* Control Byte */
gsm->fcs = gsm_fcs_add(gsm->fcs, c);
gsm->control = c;
gsm->state = GSM0_LEN0; break; case GSM0_LEN0: /* Length EA */
gsm->fcs = gsm_fcs_add(gsm->fcs, c); if (gsm_read_ea(&gsm->len, c)) { if (gsm->len > gsm->mru) {
gsm->bad_size++;
gsm->state = GSM_SEARCH; break;
}
gsm->count = 0; if (!gsm->len)
gsm->state = GSM0_FCS; else
gsm->state = GSM0_DATA; break;
}
gsm->state = GSM0_LEN1; break; case GSM0_LEN1:
gsm->fcs = gsm_fcs_add(gsm->fcs, c);
len = c;
gsm->len |= len << 7; if (gsm->len > gsm->mru) {
gsm->bad_size++;
gsm->state = GSM_SEARCH; break;
}
gsm->count = 0; if (!gsm->len)
gsm->state = GSM0_FCS; else
gsm->state = GSM0_DATA; break; case GSM0_DATA: /* Data */
gsm->buf[gsm->count++] = c; if (gsm->count >= MAX_MRU) {
gsm->bad_size++;
gsm->state = GSM_SEARCH;
} elseif (gsm->count >= gsm->len) { /* Calculate final FCS for UI frames over all data */ if ((gsm->control & ~PF) != UIH) {
gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
gsm->count);
}
gsm->state = GSM0_FCS;
} break; case GSM0_FCS: /* FCS follows the packet */
gsm->fcs = gsm_fcs_add(gsm->fcs, c);
gsm->state = GSM0_SSOF; break; case GSM0_SSOF:
gsm->state = GSM_SEARCH; if (c == GSM0_SOF)
gsm_queue(gsm); else
gsm->bad_size++; break; default:
pr_debug("%s: unhandled state: %d\n", __func__, gsm->state); break;
}
}
/** * gsm1_receive_state_check_and_fix - check and correct receive state * @gsm: gsm data for this ldisc instance * * Ensures that the current receive state is valid for advanced option mode.
*/
staticvoid gsm1_receive_state_check_and_fix(struct gsm_mux *gsm)
{ switch (gsm->state) { case GSM_SEARCH: case GSM1_START: case GSM1_ADDRESS: case GSM1_CONTROL: case GSM1_DATA: case GSM1_OVERRUN: break; default:
gsm->state = GSM_SEARCH; break;
}
}
/** * gsm1_receive - perform processing for non-transparency * @gsm: gsm data for this ldisc instance * @c: character * * Receive bytes in mode 1 (Advanced option)
*/
staticvoid gsm1_receive(struct gsm_mux *gsm, u8 c)
{
gsm1_receive_state_check_and_fix(gsm); /* handle XON/XOFF */ if ((c & ISO_IEC_646_MASK) == XON) {
gsm->constipated = true; return;
} elseif ((c & ISO_IEC_646_MASK) == XOFF) {
gsm->constipated = false; /* Kick the link in case it is idling */
gsmld_write_trigger(gsm); return;
} if (c == GSM1_SOF) { /* EOF is only valid in frame if we have got to the data state */ if (gsm->state == GSM1_DATA) { if (gsm->count < 1) { /* Missing FSC */
gsm->malformed++;
gsm->state = GSM1_START; return;
} /* Remove the FCS from data */
gsm->count--; if ((gsm->control & ~PF) != UIH) { /* Calculate final FCS for UI frames over all * data but FCS
*/
gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
gsm->count);
} /* Add the FCS itself to test against GOOD_FCS */
gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
gsm->len = gsm->count;
gsm_queue(gsm);
gsm->state = GSM1_START; return;
} /* Any partial frame was a runt so go back to start */ if (gsm->state != GSM1_START) { if (gsm->state != GSM_SEARCH)
gsm->malformed++;
gsm->state = GSM1_START;
} /* A SOF in GSM_START means we are still reading idling or
framing bytes */ return;
}
if (c == GSM1_ESCAPE) {
gsm->escape = true; return;
}
/* Only an unescaped SOF gets us out of GSM search */ if (gsm->state == GSM_SEARCH) return;
if (gsm->escape) {
c ^= GSM1_ESCAPE_BITS;
gsm->escape = false;
} switch (gsm->state) { case GSM1_START: /* First byte after SOF */
gsm->address = 0;
gsm->state = GSM1_ADDRESS;
gsm->fcs = INIT_FCS;
fallthrough; case GSM1_ADDRESS: /* Address continuation */
gsm->fcs = gsm_fcs_add(gsm->fcs, c); if (gsm_read_ea(&gsm->address, c))
gsm->state = GSM1_CONTROL; break; case GSM1_CONTROL: /* Control Byte */
gsm->fcs = gsm_fcs_add(gsm->fcs, c);
gsm->control = c;
gsm->count = 0;
gsm->state = GSM1_DATA; break; case GSM1_DATA: /* Data */ if (gsm->count > gsm->mru || gsm->count > MAX_MRU) { /* Allow one for the FCS */
gsm->state = GSM1_OVERRUN;
gsm->bad_size++;
} else
gsm->buf[gsm->count++] = c; break; case GSM1_OVERRUN: /* Over-long - eg a dropped SOF */ break; default:
pr_debug("%s: unhandled state: %d\n", __func__, gsm->state); break;
}
}
/** * gsm_error - handle tty error * @gsm: ldisc data * * Handle an error in the receipt of data for a frame. Currently we just * go back to hunting for a SOF. * * FIXME: better diagnostics ?
*/
/** * gsm_cleanup_mux - generic GSM protocol cleanup * @gsm: our mux * @disc: disconnect link? * * Clean up the bits of the mux which are the same for all framing * protocols. Remove the mux from the mux table, stop all the timers * and then shut down each device hanging up the channels as we go.
*/
/* Finish outstanding timers, making sure they are done */
timer_delete_sync(&gsm->kick_timer);
timer_delete_sync(&gsm->t2_timer);
timer_delete_sync(&gsm->ka_timer);
/* Finish writing to ldisc */
flush_work(&gsm->tx_work);
/* Free up any link layer users and finally the control channel */ if (gsm->has_devices) {
gsm_unregister_devices(gsm_tty_driver, gsm->num);
gsm->has_devices = false;
} for (i = NUM_DLCI - 1; i >= 0; i--) if (gsm->dlci[i])
gsm_dlci_release(gsm->dlci[i]);
mutex_unlock(&gsm->mutex); /* Now wipe the queues */
tty_ldisc_flush(gsm->tty);
/** * gsm_activate_mux - generic GSM setup * @gsm: our mux * * Set up the bits of the mux which are the same for all framing * protocols. Add the mux to the mux table so it can be opened and * finally kick off connecting to DLCI 0 on the modem.
*/
staticint gsm_activate_mux(struct gsm_mux *gsm)
{ struct gsm_dlci *dlci; int ret;
dlci = gsm_dlci_alloc(gsm, 0); if (dlci == NULL) return -ENOMEM;
ret = gsm_register_devices(gsm_tty_driver, gsm->num); if (ret) return ret;
gsm->has_devices = true;
gsm->dead = false; /* Tty opens are now permissible */ return 0;
}
/** * gsm_free_mux - free up a mux * @gsm: mux to free * * Dispose of allocated resources for a dead mux
*/ staticvoid gsm_free_mux(struct gsm_mux *gsm)
{ int i;
for (i = 0; i < MAX_MUX; i++) { if (gsm == gsm_mux[i]) {
gsm_mux[i] = NULL; break;
}
}
mutex_destroy(&gsm->mutex);
kfree(gsm->txframe);
kfree(gsm->buf);
kfree(gsm);
}
/** * gsm_free_muxr - free up a mux * @ref: kreference to the mux to free * * Dispose of allocated resources for a dead mux
*/ staticvoid gsm_free_muxr(struct kref *ref)
{ struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
gsm_free_mux(gsm);
}
/* Store the instance to the mux array or abort if no space is * available.
*/
spin_lock(&gsm_mux_lock); for (i = 0; i < MAX_MUX; i++) { if (!gsm_mux[i]) {
gsm_mux[i] = gsm;
gsm->num = i; break;
}
}
spin_unlock(&gsm_mux_lock); if (i == MAX_MUX) {
mutex_destroy(&gsm->mutex);
kfree(gsm->txframe);
kfree(gsm->buf);
kfree(gsm); return NULL;
}
staticint gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
{ int need_close = 0; int need_restart = 0;
/* Stuff we don't support yet - UI or I frame transport */ if (c->adaption != 1 && c->adaption != 2) return -EOPNOTSUPP; /* Check the MRU/MTU range looks sane */ if (c->mru < MIN_MTU || c->mtu < MIN_MTU) return -EINVAL; if (c->mru > MAX_MRU || c->mtu > MAX_MTU) return -EINVAL; if (c->t3 > MAX_T3) return -EINVAL; if (c->n2 > 255) return -EINVAL; if (c->encapsulation > 1) /* Basic, advanced, no I */ return -EINVAL; if (c->initiator > 1) return -EINVAL; if (c->k > MAX_WINDOW_SIZE) return -EINVAL; if (c->i == 0 || c->i > 2) /* UIH and UI only */ return -EINVAL; /* * See what is needed for reconfiguration
*/
/* Timing fields */ if (c->t1 != 0 && c->t1 != gsm->t1)
need_restart = 1; if (c->t2 != 0 && c->t2 != gsm->t2)
need_restart = 1; if (c->encapsulation != gsm->encoding)
need_restart = 1; if (c->adaption != gsm->adaption)
need_restart = 1; /* Requires care */ if (c->initiator != gsm->initiator)
need_close = 1; if (c->mru != gsm->mru)
need_restart = 1; if (c->mtu != gsm->mtu)
need_restart = 1;
/* * Close down what is needed, restart and initiate the new * configuration. On the first time there is no DLCI[0] * and closing or cleaning up is not necessary.
*/ if (need_close || need_restart)
gsm_cleanup_mux(gsm, true);
if (c->t1)
gsm->t1 = c->t1; if (c->t2)
gsm->t2 = c->t2; if (c->t3)
gsm->t3 = c->t3; if (c->k)
gsm->k = c->k;
/* * FIXME: We need to separate activation/deactivation from adding * and removing from the mux array
*/ if (gsm->dead) { int ret = gsm_activate_mux(gsm); if (ret) return ret; if (gsm->initiator)
gsm_dlci_begin_open(gsm->dlci[0]);
} return 0;
}
/* * Check that userspace doesn't put stuff in here to prevent breakages * in the future.
*/ for (i = 0; i < ARRAY_SIZE(ce->reserved); i++) if (ce->reserved[i]) return -EINVAL; if (ce->flags & ~GSM_FL_RESTART) return -EINVAL;
/* Requires care */ if (ce->flags & GSM_FL_RESTART)
need_restart = true;
/* * Close down what is needed, restart and initiate the new * configuration. On the first time there is no DLCI[0] * and closing or cleaning up is not necessary.
*/ if (need_restart)
gsm_cleanup_mux(gsm, true);
/* * Setup the new configuration values
*/
gsm->wait_config = ce->wait_config ? true : false;
gsm->keep_alive = ce->keep_alive;
if (gsm->dead) { int ret = gsm_activate_mux(gsm); if (ret) return ret; if (gsm->initiator)
gsm_dlci_begin_open(gsm->dlci[0]);
}
return 0;
}
/** * gsmld_output - write to link * @gsm: our mux * @data: bytes to output * @len: size * * Write a block of data from the GSM mux to the data channel. This * will eventually be serialized from above but at the moment isn't.
*/
/** * gsmld_write_task - ldisc write task * @work: our tx write work * * Writes out data to the ldisc if possible. We are doing this here to * avoid dead-locking. This returns if no space or data is left for output.
*/ staticvoid gsmld_write_task(struct work_struct *work)
{ struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work); unsignedlong flags; int i, ret;
/* All outstanding control channel and control messages and one data * frame is sent.
*/
ret = -ENODEV;
spin_lock_irqsave(&gsm->tx_lock, flags); if (gsm->tty)
ret = gsm_data_kick(gsm);
spin_unlock_irqrestore(&gsm->tx_lock, flags);
if (ret >= 0) for (i = 0; i < NUM_DLCI; i++) if (gsm->dlci[i])
tty_port_tty_wakeup(&gsm->dlci[i]->port);
}
/** * gsmld_attach_gsm - mode set up * @tty: our tty structure * @gsm: our mux * * Set up the MUX for basic mode and commence connecting to the * modem. Currently called from the line discipline set up but * will need moving to an ioctl path.
*/
/** * gsmld_detach_gsm - stop doing 0710 mux * @tty: tty attached to the mux * @gsm: mux * * Shutdown and then clean up the resources used by the line discipline
*/
if (debug & DBG_DATA)
gsm_hex_dump_bytes(__func__, cp, count);
for (; count; count--, cp++) { if (fp)
flags = *fp++; switch (flags) { case TTY_NORMAL: if (gsm->receive)
gsm->receive(gsm, *cp); break; case TTY_OVERRUN: case TTY_BREAK: case TTY_PARITY: case TTY_FRAME:
gsm_error(gsm); break; default:
WARN_ONCE(1, "%s: unknown flag %d\n",
tty_name(tty), flags); break;
}
} /* FASYNC if needed ? */ /* If clogged call tty_throttle(tty); */
}
/** * gsmld_flush_buffer - clean input queue * @tty: terminal device * * Flush the input buffer. Called when the line discipline is * being closed, when the tty layer wants the buffer flushed (eg * at hangup).
*/
/** * gsmld_close - close the ldisc for this tty * @tty: device * * Called from the terminal layer when this line discipline is * being shut down, either because of a close or becsuse of a * discipline change. The function will not be called while other * ldisc methods are in progress.
*/
/* The ldisc locks and closes the port before calling our close. This * means we have no way to do a proper disconnect. We will not bother * to do one.
*/
gsm_cleanup_mux(gsm, false);
gsmld_detach_gsm(tty, gsm);
gsmld_flush_buffer(tty); /* Do other clean up here */
mux_put(gsm);
}
/** * gsmld_open - open an ldisc * @tty: terminal to open * * Called when this line discipline is being attached to the * terminal device. Can sleep. Called serialized so that no * other events will occur in parallel. No further open will occur * until a close.
*/
/* Attach our ldisc data */
gsm = gsm_alloc_mux(); if (gsm == NULL) return -ENOMEM;
tty->disc_data = gsm;
tty->receive_room = 65536;
/* Attach the initial passive connection */
gsmld_attach_gsm(tty, gsm);
/* The mux will not be activated yet, we wait for correct * configuration first.
*/ if (gsm->encoding == GSM_BASIC_OPT)
gsm->receive = gsm0_receive; else
gsm->receive = gsm1_receive;
return 0;
}
/** * gsmld_write_wakeup - asynchronous I/O notifier * @tty: tty device * * Required for the ptys, serial driver etc. since processes * that attach themselves to the master and rely on ASYNC * IO must be woken up
*/
/** * gsmld_read - read function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer * @nr: size of I/O * @cookie: unused * @offset: unused * * Perform reads for the line discipline. We are guaranteed that the * line discipline will not be closed under us but we may get multiple * parallel readers and must handle this ourselves. We may also get * a hangup. Always called in user context, may sleep. * * This code must be sure never to sleep through a hangup.
*/
/** * gsmld_write - write function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer * @nr: size of I/O * * Called when the owner of the device wants to send a frame * itself (or some other control data). The data is transferred * as-is and must be properly framed and checksummed as appropriate * by userspace. Frames are either sent whole or not at all as this * avoids pain user side.
*/
ret = -ENOBUFS;
spin_lock_irqsave(&gsm->tx_lock, flags);
space = tty_write_room(tty); if (space >= nr)
ret = tty->ops->write(tty, buf, nr); else
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
spin_unlock_irqrestore(&gsm->tx_lock, flags);
return ret;
}
/** * gsmld_poll - poll method for N_GSM0710 * @tty: terminal device * @file: file accessing it * @wait: poll table * * Called when the line discipline is asked to poll() for data or * for special events. This code is not serialized with respect to * other events save open/close. * * This code must be sure never to sleep through a hangup. * Called without the kernel lock held - fine
*/
skb_queue_head(&dlci->skb_list, skb);
net->stats.tx_packets++;
net->stats.tx_bytes += skb->len;
gsm_dlci_data_kick(dlci); /* And tell the kernel when the last transmit started. */
netif_trans_update(net);
muxnet_put(mux_net); return NETDEV_TX_OK;
}
/* called when a packet did not ack after watchdogtimeout */ staticvoid gsm_mux_net_tx_timeout(struct net_device *net, unsignedint txqueue)
{ /* Tell syslog we are hosed. */
dev_dbg(&net->dev, "Tx timed out.\n");
/** * gsm_modem_upd_via_data - send modem bits via convergence layer * @dlci: channel * @brk: break signal * * Send an empty frame to signal mobile state changes and to transmit the * break signal for adaption 2.
*/
/** * gsm_modem_send_initial_msc - Send initial modem status message * * @dlci channel * * Send an initial MSC message after DLCI open to set the initial * modem status lines. This is only done for basic mode. * Does not wait for a response as we cannot block the input queue * processing.
*/ staticint gsm_modem_send_initial_msc(struct gsm_dlci *dlci)
{
u8 modembits[2];
if (dlci->adaption != 1 || dlci->gsm->encoding != GSM_BASIC_OPT) return 0;
/** * gsm_modem_update - send modem status line state * @dlci: channel * @brk: break signal
*/
staticint gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
{ if (dlci->gsm->dead) return -EL2HLT; if (dlci->adaption == 2) { /* Send convergence layer type 2 empty data frame. */
gsm_modem_upd_via_data(dlci, brk); return 0;
} elseif (dlci->gsm->encoding == GSM_BASIC_OPT) { /* Send as MSC control message. */ return gsm_modem_upd_via_msc(dlci, brk);
}
/* Modem status lines are not supported. */ return -EPROTONOSUPPORT;
}
/** * gsm_wait_modem_change - wait for modem status line change * @dlci: channel * @mask: modem status line bits * * The function returns if: * - any given modem status line bit changed * - the wait event function got interrupted (e.g. by a signal) * - the underlying DLCI was closed * - the underlying ldisc device was removed
*/ staticint gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask)
{ struct gsm_mux *gsm = dlci->gsm;
u32 old = dlci->modem_rx; int ret;
ret = wait_event_interruptible(gsm->event, gsm->dead ||
dlci->state != DLCI_OPEN ||
(old ^ dlci->modem_rx) & mask); if (gsm->dead) return -ENODEV; if (dlci->state != DLCI_OPEN) return -EL2NSYNC; return ret;
}
/* Not yet open so no carrier info */ if (dlci->state != DLCI_OPEN) returnfalse; if (debug & DBG_CD_ON) returntrue;
/* * Basic mode with control channel in ADM mode may not respond * to CMD_MSC at all and modem_rx is empty.
*/ if (gsm->encoding == GSM_BASIC_OPT &&
gsm->dlci[0]->mode == DLCI_MODE_ADM && !dlci->modem_rx) returntrue;
if (mux >= MAX_MUX) return -ENXIO; /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */ if (gsm_mux[mux] == NULL) return -EUNATCH; if (line == 0 || line > 61) /* 62/63 reserved */ return -ECHRNG;
gsm = gsm_mux[mux]; if (gsm->dead) return -EL2HLT; /* If DLCI 0 is not yet fully open return an error. This is ok from a locking perspective as we don't have to worry about this
if DLCI0 is lost */
mutex_lock(&gsm->mutex);
dlci->modem_rx = 0; /* We could in theory open and close before we wait - eg if we get
a DM straight back. This is ok as that will have caused a hangup */
tty_port_set_initialized(port, true); /* Start sending off SABM messages */ if (!dlci->gsm->wait_config) { /* Start sending off SABM messages */ if (dlci->gsm->initiator)
gsm_dlci_begin_open(dlci); else
gsm_dlci_set_opening(dlci);
} else {
gsm_dlci_set_wait_config(dlci);
} /* And wait for virtual carrier */ return tty_port_block_til_ready(port, tty, filp);
}
if (dlci->state == DLCI_CLOSED) return; /* Caution needed: If we implement reliable transport classes then the data being transmitted can't simply be junked once it has first hit the stack. Until then we can just blow it
away */
spin_lock_irqsave(&dlci->lock, flags);
kfifo_reset(&dlci->fifo);
spin_unlock_irqrestore(&dlci->lock, flags); /* Need to unhook this DLCI from the transmit queue logic */
}
staticvoid gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
{ /* The FIFO handles the queue so the kernel will do the right thing waiting on chars_in_buffer before calling us. No work
to do here */
}
if (dlci->state == DLCI_CLOSED) return -EINVAL; switch (cmd) { case GSMIOC_ENABLE_NET: if (copy_from_user(&nc, (void __user *)arg, sizeof(nc))) return -EFAULT;
nc.if_name[IFNAMSIZ-1] = '\0'; /* return net interface index or error code */
mutex_lock(&dlci->mutex);
index = gsm_create_network(dlci, &nc);
mutex_unlock(&dlci->mutex); if (copy_to_user((void __user *)arg, &nc, sizeof(nc))) return -EFAULT; return index; case GSMIOC_DISABLE_NET: if (!capable(CAP_NET_ADMIN)) return -EPERM;
mutex_lock(&dlci->mutex);
gsm_destroy_network(dlci);
mutex_unlock(&dlci->mutex); return 0; case GSMIOC_GETCONF_DLCI: if (copy_from_user(&dc, (void __user *)arg, sizeof(dc))) return -EFAULT; if (dc.channel != dlci->addr) return -EPERM;
gsm_dlci_copy_config_values(dlci, &dc); if (copy_to_user((void __user *)arg, &dc, sizeof(dc))) return -EFAULT; return 0; case GSMIOC_SETCONF_DLCI: if (copy_from_user(&dc, (void __user *)arg, sizeof(dc))) return -EFAULT; if (dc.channel >= NUM_DLCI) return -EINVAL; if (dc.channel != 0 && dc.channel != dlci->addr) return -EPERM; return gsm_dlci_config(dlci, &dc, 1); case TIOCMIWAIT: return gsm_wait_modem_change(dlci, (u32)arg); default: return -ENOIOCTLCMD;
}
}
staticvoid gsmtty_set_termios(struct tty_struct *tty, conststruct ktermios *old)
{ struct gsm_dlci *dlci = tty->driver_data; if (dlci->state == DLCI_CLOSED) return; /* For the moment its fixed. In actual fact the speed information for the virtual channel can be propogated in both directions by the RPN control message. This however rapidly gets nasty as we then have to remap modem signals each way according to whether
our virtual cable is null modem etc .. */
tty_termios_copy_hw(&tty->termios, old);
}
staticvoid gsmtty_throttle(struct tty_struct *tty)
{ struct gsm_dlci *dlci = tty->driver_data; if (dlci->state == DLCI_CLOSED) return; if (C_CRTSCTS(tty))
dlci->modem_tx &= ~TIOCM_RTS;
dlci->throttled = true; /* Send an MSC with RTS cleared */
gsm_modem_update(dlci, 0);
}
staticvoid gsmtty_unthrottle(struct tty_struct *tty)
{ struct gsm_dlci *dlci = tty->driver_data; if (dlci->state == DLCI_CLOSED) return; if (C_CRTSCTS(tty))
dlci->modem_tx |= TIOCM_RTS;
dlci->throttled = false; /* Send an MSC with RTS set */
gsm_modem_update(dlci, 0);
}
staticint gsmtty_break_ctl(struct tty_struct *tty, int state)
{ struct gsm_dlci *dlci = tty->driver_data; int encode = 0; /* Off */ if (dlci->state == DLCI_CLOSED) return -EINVAL;
if (state == -1) /* "On indefinitely" - we can't encode this
properly */
encode = 0x0F; elseif (state > 0) {
encode = state / 200; /* mS to encoding */ if (encode > 0x0F)
encode = 0x0F; /* Best effort */
} return gsm_modem_update(dlci, encode);
}
staticint __init gsm_init(void)
{ /* Fill in our line protocol discipline, and register it */ int status = tty_register_ldisc(&tty_ldisc_packet); if (status != 0) {
pr_err("n_gsm: can't register line discipline (err = %d)\n",
status); return status;
}
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