1 // SPDX-License-Identifier: GPL-2.0
3 * n_gsm.c GSM 0710 tty multiplexor
4 * Copyright (c) 2009/10 Intel Corporation
6 * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
9 * Mostly done: ioctls for setting modes/timing
10 * Partly done: hooks so you can pull off frames to non tty devs
11 * Restart DLCI 0 when it closes ?
12 * Improve the tx engine
13 * Resolve tx side locking by adding a queue_head and routing
14 * all control traffic via it
15 * General tidy/document
16 * Review the locking/move to refcounts more (mux now moved to an
17 * alloc/free model ready)
18 * Use newest tty open/close port helpers and install hooks
19 * What to do about power functions ?
20 * Termios setting and negotiation
21 * Do we need a 'which mux are you' ioctl to correlate mux and tty sets
25 #include <linux/types.h>
26 #include <linux/major.h>
27 #include <linux/errno.h>
28 #include <linux/signal.h>
29 #include <linux/fcntl.h>
30 #include <linux/sched/signal.h>
31 #include <linux/interrupt.h>
32 #include <linux/tty.h>
33 #include <linux/ctype.h>
35 #include <linux/string.h>
36 #include <linux/slab.h>
37 #include <linux/poll.h>
38 #include <linux/bitops.h>
39 #include <linux/file.h>
40 #include <linux/uaccess.h>
41 #include <linux/module.h>
42 #include <linux/timer.h>
43 #include <linux/tty_flip.h>
44 #include <linux/tty_driver.h>
45 #include <linux/serial.h>
46 #include <linux/kfifo.h>
47 #include <linux/skbuff.h>
50 #include <linux/netdevice.h>
51 #include <linux/etherdevice.h>
52 #include <linux/gsmmux.h>
55 module_param(debug, int, 0600);
57 /* Defaults: these are from the specification */
59 #define T1 10 /* 100mS */
60 #define T2 34 /* 333mS */
61 #define N2 3 /* Retry 3 times */
63 /* Use long timers for testing at low speed with debug on */
70 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
71 * limits so this is plenty
75 #define GSM_NET_TX_TIMEOUT (HZ*10)
78 * struct gsm_mux_net - network interface
79 * @struct gsm_dlci* dlci
81 * Created when net interface is initialized.
85 struct gsm_dlci *dlci;
89 * Each block of data we have queued to go out is in the form of
90 * a gsm_msg which holds everything we need in a link layer independent
95 struct list_head list;
96 u8 addr; /* DLCI address + flags */
97 u8 ctrl; /* Control byte + flags */
98 unsigned int len; /* Length of data block (can be zero) */
99 unsigned char *data; /* Points into buffer but not at the start */
100 unsigned char buffer[0];
104 * Each active data link has a gsm_dlci structure associated which ties
105 * the link layer to an optional tty (if the tty side is open). To avoid
106 * complexity right now these are only ever freed up when the mux is
109 * At the moment we don't free DLCI objects until the mux is torn down
110 * this avoid object life time issues but might be worth review later.
117 #define DLCI_CLOSED 0
118 #define DLCI_OPENING 1 /* Sending SABM not seen UA */
119 #define DLCI_OPEN 2 /* SABM/UA complete */
120 #define DLCI_CLOSING 3 /* Sending DISC not seen UA/DM */
125 #define DLCI_MODE_ABM 0 /* Normal Asynchronous Balanced Mode */
126 #define DLCI_MODE_ADM 1 /* Asynchronous Disconnected Mode */
127 spinlock_t lock; /* Protects the internal state */
128 struct timer_list t1; /* Retransmit timer for SABM and UA */
130 /* Uplink tty if active */
131 struct tty_port port; /* The tty bound to this DLCI if there is one */
132 struct kfifo *fifo; /* Queue fifo for the DLCI */
133 struct kfifo _fifo; /* For new fifo API porting only */
134 int adaption; /* Adaption layer in use */
136 u32 modem_rx; /* Our incoming virtual modem lines */
137 u32 modem_tx; /* Our outgoing modem lines */
138 int dead; /* Refuse re-open */
140 int throttled; /* Private copy of throttle state */
141 int constipated; /* Throttle status for outgoing */
143 struct sk_buff *skb; /* Frame being sent */
144 struct sk_buff_head skb_list; /* Queued frames */
145 /* Data handling callback */
146 void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
147 void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
148 struct net_device *net; /* network interface, if created */
151 /* DLCI 0, 62/63 are special or reserved see gsmtty_open */
156 * DLCI 0 is used to pass control blocks out of band of the data
157 * flow (and with a higher link priority). One command can be outstanding
158 * at a time and we use this structure to manage them. They are created
159 * and destroyed by the user context, and updated by the receive paths
164 u8 cmd; /* Command we are issuing */
165 u8 *data; /* Data for the command in case we retransmit */
166 int len; /* Length of block for retransmission */
167 int done; /* Done flag */
168 int error; /* Error if any */
172 * Each GSM mux we have is represented by this structure. If we are
173 * operating as an ldisc then we use this structure as our ldisc
174 * state. We need to sort out lifetimes and locking with respect
175 * to the gsm mux array. For now we don't free DLCI objects that
176 * have been instantiated until the mux itself is terminated.
178 * To consider further: tty open versus mux shutdown.
182 struct tty_struct *tty; /* The tty our ldisc is bound to */
188 /* Events on the GSM channel */
189 wait_queue_head_t event;
191 /* Bits for GSM mode decoding */
198 #define GSM_ADDRESS 2
199 #define GSM_CONTROL 3
203 #define GSM_OVERRUN 7
208 unsigned int address;
215 u8 *txframe; /* TX framing buffer */
217 /* Methods for the receiver side */
218 void (*receive)(struct gsm_mux *gsm, u8 ch);
219 void (*error)(struct gsm_mux *gsm, u8 ch, u8 flag);
220 /* And transmit side */
221 int (*output)(struct gsm_mux *mux, u8 *data, int len);
226 int initiator; /* Did we initiate connection */
227 int dead; /* Has the mux been shut down */
228 struct gsm_dlci *dlci[NUM_DLCI];
229 int constipated; /* Asked by remote to shut up */
232 unsigned int tx_bytes; /* TX data outstanding */
233 #define TX_THRESH_HI 8192
234 #define TX_THRESH_LO 2048
235 struct list_head tx_list; /* Pending data packets */
237 /* Control messages */
238 struct timer_list t2_timer; /* Retransmit timer for commands */
239 int cretries; /* Command retry counter */
240 struct gsm_control *pending_cmd;/* Our current pending command */
241 spinlock_t control_lock; /* Protects the pending command */
244 int adaption; /* 1 or 2 supported */
245 u8 ftype; /* UI or UIH */
246 int t1, t2; /* Timers in 1/100th of a sec */
247 int n2; /* Retry count */
249 /* Statistics (not currently exposed) */
250 unsigned long bad_fcs;
251 unsigned long malformed;
252 unsigned long io_error;
253 unsigned long bad_size;
254 unsigned long unsupported;
259 * Mux objects - needed so that we can translate a tty index into the
260 * relevant mux and DLCI.
263 #define MAX_MUX 4 /* 256 minors */
264 static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */
265 static spinlock_t gsm_mux_lock;
267 static struct tty_driver *gsm_tty_driver;
270 * This section of the driver logic implements the GSM encodings
271 * both the basic and the 'advanced'. Reliable transport is not
279 /* I is special: the rest are ..*/
290 /* Channel commands */
292 #define CMD_TEST 0x11
295 #define CMD_FCOFF 0x31
298 #define CMD_FCON 0x51
303 /* Virtual modem bits */
310 #define GSM0_SOF 0xF9
311 #define GSM1_SOF 0x7E
312 #define GSM1_ESCAPE 0x7D
313 #define GSM1_ESCAPE_BITS 0x20
317 static const struct tty_port_operations gsm_port_ops;
320 * CRC table for GSM 0710
323 static const u8 gsm_fcs8[256] = {
324 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
325 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
326 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
327 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
328 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
329 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
330 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
331 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
332 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
333 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
334 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
335 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
336 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
337 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
338 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
339 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
340 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
341 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
342 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
343 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
344 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
345 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
346 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
347 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
348 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
349 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
350 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
351 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
352 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
353 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
354 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
355 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
358 #define INIT_FCS 0xFF
359 #define GOOD_FCS 0xCF
362 * gsm_fcs_add - update FCS
366 * Update the FCS to include c. Uses the algorithm in the specification
370 static inline u8 gsm_fcs_add(u8 fcs, u8 c)
372 return gsm_fcs8[fcs ^ c];
376 * gsm_fcs_add_block - update FCS for a block
379 * @len: length of buffer
381 * Update the FCS to include c. Uses the algorithm in the specification
385 static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
388 fcs = gsm_fcs8[fcs ^ *c++];
393 * gsm_read_ea - read a byte into an EA
394 * @val: variable holding value
395 * c: byte going into the EA
397 * Processes one byte of an EA. Updates the passed variable
398 * and returns 1 if the EA is now completely read
401 static int gsm_read_ea(unsigned int *val, u8 c)
403 /* Add the next 7 bits into the value */
406 /* Was this the last byte of the EA 1 = yes*/
411 * gsm_encode_modem - encode modem data bits
412 * @dlci: DLCI to encode from
414 * Returns the correct GSM encoded modem status bits (6 bit field) for
415 * the current status of the DLCI and attached tty object
418 static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
421 /* FC is true flow control not modem bits */
424 if (dlci->modem_tx & TIOCM_DTR)
425 modembits |= MDM_RTC;
426 if (dlci->modem_tx & TIOCM_RTS)
427 modembits |= MDM_RTR;
428 if (dlci->modem_tx & TIOCM_RI)
430 if (dlci->modem_tx & TIOCM_CD)
436 * gsm_print_packet - display a frame for debug
437 * @hdr: header to print before decode
438 * @addr: address EA from the frame
439 * @cr: C/R bit from the frame
440 * @control: control including PF bit
441 * @data: following data bytes
442 * @dlen: length of data
444 * Displays a packet in human readable format for debugging purposes. The
445 * style is based on amateur radio LAP-B dump display.
448 static void gsm_print_packet(const char *hdr, int addr, int cr,
449 u8 control, const u8 *data, int dlen)
454 pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
456 switch (control & ~PF) {
476 if (!(control & 0x01)) {
477 pr_cont("I N(S)%d N(R)%d",
478 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
479 } else switch (control & 0x0F) {
481 pr_cont("RR(%d)", (control & 0xE0) >> 5);
484 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
487 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
490 pr_cont("[%02X]", control);
506 pr_cont("%02X ", *data++);
515 * Link level transmission side
519 * gsm_stuff_packet - bytestuff a packet
522 * @len: length of input
524 * Expand a buffer by bytestuffing it. The worst case size change
525 * is doubling and the caller is responsible for handing out
526 * suitable sized buffers.
529 static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
533 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
534 || *input == XON || *input == XOFF) {
535 *output++ = GSM1_ESCAPE;
536 *output++ = *input++ ^ GSM1_ESCAPE_BITS;
539 *output++ = *input++;
546 * gsm_send - send a control frame
548 * @addr: address for control frame
549 * @cr: command/response bit
550 * @control: control byte including PF bit
552 * Format up and transmit a control frame. These do not go via the
553 * queueing logic as they should be transmitted ahead of data when
556 * FIXME: Lock versus data TX path
559 static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
565 switch (gsm->encoding) {
568 cbuf[1] = (addr << 2) | (cr << 1) | EA;
570 cbuf[3] = EA; /* Length of data = 0 */
571 cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
577 /* Control frame + packing (but not frame stuffing) in mode 1 */
578 ibuf[0] = (addr << 2) | (cr << 1) | EA;
580 ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
581 /* Stuffing may double the size worst case */
582 len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
583 /* Now add the SOF markers */
585 cbuf[len + 1] = GSM1_SOF;
586 /* FIXME: we can omit the lead one in many cases */
593 gsm->output(gsm, cbuf, len);
594 gsm_print_packet("-->", addr, cr, control, NULL, 0);
598 * gsm_response - send a control response
600 * @addr: address for control frame
601 * @control: control byte including PF bit
603 * Format up and transmit a link level response frame.
606 static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
608 gsm_send(gsm, addr, 0, control);
612 * gsm_command - send a control command
614 * @addr: address for control frame
615 * @control: control byte including PF bit
617 * Format up and transmit a link level command frame.
620 static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
622 gsm_send(gsm, addr, 1, control);
625 /* Data transmission */
627 #define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
630 * gsm_data_alloc - allocate data frame
632 * @addr: DLCI address
633 * @len: length excluding header and FCS
634 * @ctrl: control byte
636 * Allocate a new data buffer for sending frames with data. Space is left
637 * at the front for header bytes but that is treated as an implementation
638 * detail and not for the high level code to use
641 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
644 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
648 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */
652 INIT_LIST_HEAD(&m->list);
657 * gsm_data_kick - poke the queue
660 * The tty device has called us to indicate that room has appeared in
661 * the transmit queue. Ram more data into the pipe if we have any
662 * If we have been flow-stopped by a CMD_FCOFF, then we can only
663 * send messages on DLCI0 until CMD_FCON
665 * FIXME: lock against link layer control transmissions
668 static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
670 struct gsm_msg *msg, *nmsg;
673 list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
674 if (gsm->constipated && msg->addr)
676 if (gsm->encoding != 0) {
677 gsm->txframe[0] = GSM1_SOF;
678 len = gsm_stuff_frame(msg->data,
679 gsm->txframe + 1, msg->len);
680 gsm->txframe[len + 1] = GSM1_SOF;
683 gsm->txframe[0] = GSM0_SOF;
684 memcpy(gsm->txframe + 1 , msg->data, msg->len);
685 gsm->txframe[msg->len + 1] = GSM0_SOF;
690 print_hex_dump_bytes("gsm_data_kick: ",
693 if (gsm->output(gsm, gsm->txframe, len) < 0)
695 /* FIXME: Can eliminate one SOF in many more cases */
696 gsm->tx_bytes -= msg->len;
698 list_del(&msg->list);
702 tty_port_tty_wakeup(&dlci->port);
706 for (i = 0; i < NUM_DLCI; i++)
708 tty_port_tty_wakeup(&gsm->dlci[i]->port);
714 * __gsm_data_queue - queue a UI or UIH frame
715 * @dlci: DLCI sending the data
716 * @msg: message queued
718 * Add data to the transmit queue and try and get stuff moving
719 * out of the mux tty if not already doing so. The Caller must hold
723 static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
725 struct gsm_mux *gsm = dlci->gsm;
727 u8 *fcs = dp + msg->len;
729 /* Fill in the header */
730 if (gsm->encoding == 0) {
732 *--dp = (msg->len << 1) | EA;
734 *--dp = (msg->len >> 7); /* bits 7 - 15 */
735 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
741 *--dp = (msg->addr << 2) | 2 | EA;
743 *--dp = (msg->addr << 2) | EA;
744 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
745 /* Ugly protocol layering violation */
746 if (msg->ctrl == UI || msg->ctrl == (UI|PF))
747 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
750 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
751 msg->data, msg->len);
753 /* Move the header back and adjust the length, also allow for the FCS
754 now tacked on the end */
755 msg->len += (msg->data - dp) + 1;
758 /* Add to the actual output queue */
759 list_add_tail(&msg->list, &gsm->tx_list);
760 gsm->tx_bytes += msg->len;
761 gsm_data_kick(gsm, dlci);
765 * gsm_data_queue - queue a UI or UIH frame
766 * @dlci: DLCI sending the data
767 * @msg: message queued
769 * Add data to the transmit queue and try and get stuff moving
770 * out of the mux tty if not already doing so. Take the
771 * the gsm tx lock and dlci lock.
774 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
777 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
778 __gsm_data_queue(dlci, msg);
779 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
783 * gsm_dlci_data_output - try and push data out of a DLCI
785 * @dlci: the DLCI to pull data from
787 * Pull data from a DLCI and send it into the transmit queue if there
788 * is data. Keep to the MRU of the mux. This path handles the usual tty
789 * interface which is a byte stream with optional modem data.
791 * Caller must hold the tx_lock of the mux.
794 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
798 int len, total_size, size;
799 int h = dlci->adaption - 1;
803 len = kfifo_len(dlci->fifo);
807 /* MTU/MRU count only the data bits */
813 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
814 /* FIXME: need a timer or something to kick this so it can't
815 get stuck with no work outstanding and no buffer free */
819 switch (dlci->adaption) {
820 case 1: /* Unstructured */
822 case 2: /* Unstructed with modem bits.
823 Always one byte as we never send inline break data */
824 *dp++ = gsm_encode_modem(dlci);
827 WARN_ON(kfifo_out_locked(dlci->fifo, dp , len, &dlci->lock) != len);
828 __gsm_data_queue(dlci, msg);
831 /* Bytes of data we used up */
836 * gsm_dlci_data_output_framed - try and push data out of a DLCI
838 * @dlci: the DLCI to pull data from
840 * Pull data from a DLCI and send it into the transmit queue if there
841 * is data. Keep to the MRU of the mux. This path handles framed data
842 * queued as skbuffs to the DLCI.
844 * Caller must hold the tx_lock of the mux.
847 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
848 struct gsm_dlci *dlci)
853 int last = 0, first = 0;
856 /* One byte per frame is used for B/F flags */
857 if (dlci->adaption == 4)
860 /* dlci->skb is locked by tx_lock */
861 if (dlci->skb == NULL) {
862 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
863 if (dlci->skb == NULL)
867 len = dlci->skb->len + overhead;
869 /* MTU/MRU count only the data bits */
870 if (len > gsm->mtu) {
871 if (dlci->adaption == 3) {
872 /* Over long frame, bin it */
873 dev_kfree_skb_any(dlci->skb);
881 size = len + overhead;
882 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
884 /* FIXME: need a timer or something to kick this so it can't
885 get stuck with no work outstanding and no buffer free */
887 skb_queue_tail(&dlci->skb_list, dlci->skb);
893 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
894 /* Flag byte to carry the start/end info */
895 *dp++ = last << 7 | first << 6 | 1; /* EA */
898 memcpy(dp, dlci->skb->data, len);
899 skb_pull(dlci->skb, len);
900 __gsm_data_queue(dlci, msg);
902 dev_kfree_skb_any(dlci->skb);
909 * gsm_dlci_data_sweep - look for data to send
912 * Sweep the GSM mux channels in priority order looking for ones with
913 * data to send. We could do with optimising this scan a bit. We aim
914 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
915 * TX_THRESH_LO we get called again
917 * FIXME: We should round robin between groups and in theory you can
918 * renegotiate DLCI priorities with optional stuff. Needs optimising.
921 static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
924 /* Priority ordering: We should do priority with RR of the groups */
927 while (i < NUM_DLCI) {
928 struct gsm_dlci *dlci;
930 if (gsm->tx_bytes > TX_THRESH_HI)
933 if (dlci == NULL || dlci->constipated) {
937 if (dlci->adaption < 3 && !dlci->net)
938 len = gsm_dlci_data_output(gsm, dlci);
940 len = gsm_dlci_data_output_framed(gsm, dlci);
943 /* DLCI empty - try the next */
950 * gsm_dlci_data_kick - transmit if possible
951 * @dlci: DLCI to kick
953 * Transmit data from this DLCI if the queue is empty. We can't rely on
954 * a tty wakeup except when we filled the pipe so we need to fire off
955 * new data ourselves in other cases.
958 static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
963 if (dlci->constipated)
966 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
967 /* If we have nothing running then we need to fire up */
968 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
969 if (dlci->gsm->tx_bytes == 0) {
971 gsm_dlci_data_output_framed(dlci->gsm, dlci);
973 gsm_dlci_data_output(dlci->gsm, dlci);
976 gsm_dlci_data_sweep(dlci->gsm);
977 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
981 * Control message processing
986 * gsm_control_reply - send a response frame to a control
988 * @cmd: the command to use
989 * @data: data to follow encoded info
990 * @dlen: length of data
992 * Encode up and queue a UI/UIH frame containing our response.
995 static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
999 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
1002 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
1003 msg->data[1] = (dlen << 1) | EA;
1004 memcpy(msg->data + 2, data, dlen);
1005 gsm_data_queue(gsm->dlci[0], msg);
1009 * gsm_process_modem - process received modem status
1010 * @tty: virtual tty bound to the DLCI
1011 * @dlci: DLCI to affect
1012 * @modem: modem bits (full EA)
1014 * Used when a modem control message or line state inline in adaption
1015 * layer 2 is processed. Sort out the local modem state and throttles
1018 static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1019 u32 modem, int clen)
1025 /* The modem status command can either contain one octet (v.24 signals)
1026 or two octets (v.24 signals + break signals). The length field will
1027 either be 2 or 3 respectively. This is specified in section
1028 5.4.6.3.7 of the 27.010 mux spec. */
1031 modem = modem & 0x7f;
1034 modem = (modem >> 7) & 0x7f;
1037 /* Flow control/ready to communicate */
1038 fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1039 if (fc && !dlci->constipated) {
1040 /* Need to throttle our output on this device */
1041 dlci->constipated = 1;
1042 } else if (!fc && dlci->constipated) {
1043 dlci->constipated = 0;
1044 gsm_dlci_data_kick(dlci);
1047 /* Map modem bits */
1048 if (modem & MDM_RTC)
1049 mlines |= TIOCM_DSR | TIOCM_DTR;
1050 if (modem & MDM_RTR)
1051 mlines |= TIOCM_RTS | TIOCM_CTS;
1057 /* Carrier drop -> hangup */
1059 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1064 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1065 dlci->modem_rx = mlines;
1069 * gsm_control_modem - modem status received
1071 * @data: data following command
1072 * @clen: command length
1074 * We have received a modem status control message. This is used by
1075 * the GSM mux protocol to pass virtual modem line status and optionally
1076 * to indicate break signals. Unpack it, convert to Linux representation
1077 * and if need be stuff a break message down the tty.
1080 static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1082 unsigned int addr = 0;
1083 unsigned int modem = 0;
1084 unsigned int brk = 0;
1085 struct gsm_dlci *dlci;
1087 const u8 *dp = data;
1088 struct tty_struct *tty;
1090 while (gsm_read_ea(&addr, *dp++) == 0) {
1095 /* Must be at least one byte following the EA */
1101 /* Closed port, or invalid ? */
1102 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1104 dlci = gsm->dlci[addr];
1106 while (gsm_read_ea(&modem, *dp++) == 0) {
1113 while (gsm_read_ea(&brk, *dp++) == 0) {
1119 modem |= (brk & 0x7f);
1121 tty = tty_port_tty_get(&dlci->port);
1122 gsm_process_modem(tty, dlci, modem, clen);
1127 gsm_control_reply(gsm, CMD_MSC, data, clen);
1131 * gsm_control_rls - remote line status
1134 * @clen: data length
1136 * The modem sends us a two byte message on the control channel whenever
1137 * it wishes to send us an error state from the virtual link. Stuff
1138 * this into the uplink tty if present
1141 static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1143 struct tty_port *port;
1144 unsigned int addr = 0;
1147 const u8 *dp = data;
1149 while (gsm_read_ea(&addr, *dp++) == 0) {
1154 /* Must be at least one byte following ea */
1159 /* Closed port, or invalid ? */
1160 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1164 if ((bits & 1) == 0)
1167 port = &gsm->dlci[addr]->port;
1170 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1172 tty_insert_flip_char(port, 0, TTY_PARITY);
1174 tty_insert_flip_char(port, 0, TTY_FRAME);
1176 tty_flip_buffer_push(port);
1178 gsm_control_reply(gsm, CMD_RLS, data, clen);
1181 static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1184 * gsm_control_message - DLCI 0 control processing
1186 * @command: the command EA
1187 * @data: data beyond the command/length EAs
1190 * Input processor for control messages from the other end of the link.
1191 * Processes the incoming request and queues a response frame or an
1192 * NSC response if not supported
1195 static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1196 const u8 *data, int clen)
1199 unsigned long flags;
1203 struct gsm_dlci *dlci = gsm->dlci[0];
1204 /* Modem wishes to close down */
1208 gsm_dlci_begin_close(dlci);
1213 /* Modem wishes to test, reply with the data */
1214 gsm_control_reply(gsm, CMD_TEST, data, clen);
1217 /* Modem can accept data again */
1218 gsm->constipated = 0;
1219 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1220 /* Kick the link in case it is idling */
1221 spin_lock_irqsave(&gsm->tx_lock, flags);
1222 gsm_data_kick(gsm, NULL);
1223 spin_unlock_irqrestore(&gsm->tx_lock, flags);
1226 /* Modem wants us to STFU */
1227 gsm->constipated = 1;
1228 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1231 /* Out of band modem line change indicator for a DLCI */
1232 gsm_control_modem(gsm, data, clen);
1235 /* Out of band error reception for a DLCI */
1236 gsm_control_rls(gsm, data, clen);
1239 /* Modem wishes to enter power saving state */
1240 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1242 /* Optional unsupported commands */
1243 case CMD_PN: /* Parameter negotiation */
1244 case CMD_RPN: /* Remote port negotiation */
1245 case CMD_SNC: /* Service negotiation command */
1247 /* Reply to bad commands with an NSC */
1249 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1255 * gsm_control_response - process a response to our control
1257 * @command: the command (response) EA
1258 * @data: data beyond the command/length EA
1261 * Process a response to an outstanding command. We only allow a single
1262 * control message in flight so this is fairly easy. All the clean up
1263 * is done by the caller, we just update the fields, flag it as done
1267 static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1268 const u8 *data, int clen)
1270 struct gsm_control *ctrl;
1271 unsigned long flags;
1273 spin_lock_irqsave(&gsm->control_lock, flags);
1275 ctrl = gsm->pending_cmd;
1276 /* Does the reply match our command */
1278 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1279 /* Our command was replied to, kill the retry timer */
1280 del_timer(&gsm->t2_timer);
1281 gsm->pending_cmd = NULL;
1282 /* Rejected by the other end */
1283 if (command == CMD_NSC)
1284 ctrl->error = -EOPNOTSUPP;
1286 wake_up(&gsm->event);
1288 spin_unlock_irqrestore(&gsm->control_lock, flags);
1292 * gsm_control_transmit - send control packet
1294 * @ctrl: frame to send
1296 * Send out a pending control command (called under control lock)
1299 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1301 struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
1304 msg->data[0] = (ctrl->cmd << 1) | 2 | EA; /* command */
1305 memcpy(msg->data + 1, ctrl->data, ctrl->len);
1306 gsm_data_queue(gsm->dlci[0], msg);
1310 * gsm_control_retransmit - retransmit a control frame
1311 * @data: pointer to our gsm object
1313 * Called off the T2 timer expiry in order to retransmit control frames
1314 * that have been lost in the system somewhere. The control_lock protects
1315 * us from colliding with another sender or a receive completion event.
1316 * In that situation the timer may still occur in a small window but
1317 * gsm->pending_cmd will be NULL and we just let the timer expire.
1320 static void gsm_control_retransmit(struct timer_list *t)
1322 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
1323 struct gsm_control *ctrl;
1324 unsigned long flags;
1325 spin_lock_irqsave(&gsm->control_lock, flags);
1326 ctrl = gsm->pending_cmd;
1329 if (gsm->cretries == 0) {
1330 gsm->pending_cmd = NULL;
1331 ctrl->error = -ETIMEDOUT;
1333 spin_unlock_irqrestore(&gsm->control_lock, flags);
1334 wake_up(&gsm->event);
1337 gsm_control_transmit(gsm, ctrl);
1338 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1340 spin_unlock_irqrestore(&gsm->control_lock, flags);
1344 * gsm_control_send - send a control frame on DLCI 0
1345 * @gsm: the GSM channel
1346 * @command: command to send including CR bit
1347 * @data: bytes of data (must be kmalloced)
1348 * @len: length of the block to send
1350 * Queue and dispatch a control command. Only one command can be
1351 * active at a time. In theory more can be outstanding but the matching
1352 * gets really complicated so for now stick to one outstanding.
1355 static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1356 unsigned int command, u8 *data, int clen)
1358 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1360 unsigned long flags;
1364 wait_event(gsm->event, gsm->pending_cmd == NULL);
1365 spin_lock_irqsave(&gsm->control_lock, flags);
1366 if (gsm->pending_cmd != NULL) {
1367 spin_unlock_irqrestore(&gsm->control_lock, flags);
1370 ctrl->cmd = command;
1373 gsm->pending_cmd = ctrl;
1375 /* If DLCI0 is in ADM mode skip retries, it won't respond */
1376 if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
1379 gsm->cretries = gsm->n2;
1381 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1382 gsm_control_transmit(gsm, ctrl);
1383 spin_unlock_irqrestore(&gsm->control_lock, flags);
1388 * gsm_control_wait - wait for a control to finish
1390 * @control: control we are waiting on
1392 * Waits for the control to complete or time out. Frees any used
1393 * resources and returns 0 for success, or an error if the remote
1394 * rejected or ignored the request.
1397 static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
1400 wait_event(gsm->event, control->done == 1);
1401 err = control->error;
1408 * DLCI level handling: Needs krefs
1412 * State transitions and timers
1416 * gsm_dlci_close - a DLCI has closed
1417 * @dlci: DLCI that closed
1419 * Perform processing when moving a DLCI into closed state. If there
1420 * is an attached tty this is hung up
1423 static void gsm_dlci_close(struct gsm_dlci *dlci)
1425 del_timer(&dlci->t1);
1427 pr_debug("DLCI %d goes closed.\n", dlci->addr);
1428 dlci->state = DLCI_CLOSED;
1429 if (dlci->addr != 0) {
1430 tty_port_tty_hangup(&dlci->port, false);
1431 kfifo_reset(dlci->fifo);
1433 dlci->gsm->dead = 1;
1434 wake_up(&dlci->gsm->event);
1435 /* A DLCI 0 close is a MUX termination so we need to kick that
1436 back to userspace somehow */
1440 * gsm_dlci_open - a DLCI has opened
1441 * @dlci: DLCI that opened
1443 * Perform processing when moving a DLCI into open state.
1446 static void gsm_dlci_open(struct gsm_dlci *dlci)
1448 /* Note that SABM UA .. SABM UA first UA lost can mean that we go
1450 del_timer(&dlci->t1);
1451 /* This will let a tty open continue */
1452 dlci->state = DLCI_OPEN;
1454 pr_debug("DLCI %d goes open.\n", dlci->addr);
1455 wake_up(&dlci->gsm->event);
1459 * gsm_dlci_t1 - T1 timer expiry
1460 * @dlci: DLCI that opened
1462 * The T1 timer handles retransmits of control frames (essentially of
1463 * SABM and DISC). We resend the command until the retry count runs out
1464 * in which case an opening port goes back to closed and a closing port
1465 * is simply put into closed state (any further frames from the other
1466 * end will get a DM response)
1468 * Some control dlci can stay in ADM mode with other dlci working just
1469 * fine. In that case we can just keep the control dlci open after the
1470 * DLCI_OPENING retries time out.
1473 static void gsm_dlci_t1(struct timer_list *t)
1475 struct gsm_dlci *dlci = from_timer(dlci, t, t1);
1476 struct gsm_mux *gsm = dlci->gsm;
1478 switch (dlci->state) {
1481 if (dlci->retries) {
1482 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1483 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1484 } else if (!dlci->addr && gsm->control == (DM | PF)) {
1486 pr_info("DLCI %d opening in ADM mode.\n",
1488 dlci->mode = DLCI_MODE_ADM;
1489 gsm_dlci_open(dlci);
1491 gsm_dlci_close(dlci);
1497 if (dlci->retries) {
1498 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1499 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1501 gsm_dlci_close(dlci);
1507 * gsm_dlci_begin_open - start channel open procedure
1508 * @dlci: DLCI to open
1510 * Commence opening a DLCI from the Linux side. We issue SABM messages
1511 * to the modem which should then reply with a UA or ADM, at which point
1512 * we will move into open state. Opening is done asynchronously with retry
1513 * running off timers and the responses.
1516 static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
1518 struct gsm_mux *gsm = dlci->gsm;
1519 if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING)
1521 dlci->retries = gsm->n2;
1522 dlci->state = DLCI_OPENING;
1523 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1524 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1528 * gsm_dlci_begin_close - start channel open procedure
1529 * @dlci: DLCI to open
1531 * Commence closing a DLCI from the Linux side. We issue DISC messages
1532 * to the modem which should then reply with a UA, at which point we
1533 * will move into closed state. Closing is done asynchronously with retry
1534 * off timers. We may also receive a DM reply from the other end which
1535 * indicates the channel was already closed.
1538 static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
1540 struct gsm_mux *gsm = dlci->gsm;
1541 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
1543 dlci->retries = gsm->n2;
1544 dlci->state = DLCI_CLOSING;
1545 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1546 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1550 * gsm_dlci_data - data arrived
1552 * @data: block of bytes received
1553 * @len: length of received block
1555 * A UI or UIH frame has arrived which contains data for a channel
1556 * other than the control channel. If the relevant virtual tty is
1557 * open we shovel the bits down it, if not we drop them.
1560 static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
1563 struct tty_port *port = &dlci->port;
1564 struct tty_struct *tty;
1565 unsigned int modem = 0;
1569 pr_debug("%d bytes for tty\n", len);
1570 switch (dlci->adaption) {
1571 /* Unsupported types */
1572 case 4: /* Packetised interruptible data */
1574 case 3: /* Packetised uininterruptible voice/data */
1576 case 2: /* Asynchronous serial with line state in each frame */
1577 while (gsm_read_ea(&modem, *data++) == 0) {
1582 tty = tty_port_tty_get(port);
1584 gsm_process_modem(tty, dlci, modem, clen);
1588 case 1: /* Line state will go via DLCI 0 controls only */
1590 tty_insert_flip_string(port, data, len);
1591 tty_flip_buffer_push(port);
1596 * gsm_dlci_control - data arrived on control channel
1598 * @data: block of bytes received
1599 * @len: length of received block
1601 * A UI or UIH frame has arrived which contains data for DLCI 0 the
1602 * control channel. This should contain a command EA followed by
1603 * control data bytes. The command EA contains a command/response bit
1604 * and we divide up the work accordingly.
1607 static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
1609 /* See what command is involved */
1610 unsigned int command = 0;
1612 if (gsm_read_ea(&command, *data++) == 1) {
1615 /* FIXME: this is properly an EA */
1617 /* Malformed command ? */
1621 gsm_control_message(dlci->gsm, command,
1624 gsm_control_response(dlci->gsm, command,
1632 * Allocate/Free DLCI channels
1636 * gsm_dlci_alloc - allocate a DLCI
1638 * @addr: address of the DLCI
1640 * Allocate and install a new DLCI object into the GSM mux.
1642 * FIXME: review locking races
1645 static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
1647 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
1650 spin_lock_init(&dlci->lock);
1651 mutex_init(&dlci->mutex);
1652 dlci->fifo = &dlci->_fifo;
1653 if (kfifo_alloc(&dlci->_fifo, 4096, GFP_KERNEL) < 0) {
1658 skb_queue_head_init(&dlci->skb_list);
1659 timer_setup(&dlci->t1, gsm_dlci_t1, 0);
1660 tty_port_init(&dlci->port);
1661 dlci->port.ops = &gsm_port_ops;
1664 dlci->adaption = gsm->adaption;
1665 dlci->state = DLCI_CLOSED;
1667 dlci->data = gsm_dlci_data;
1669 dlci->data = gsm_dlci_command;
1670 gsm->dlci[addr] = dlci;
1675 * gsm_dlci_free - free DLCI
1676 * @dlci: DLCI to free
1682 static void gsm_dlci_free(struct tty_port *port)
1684 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
1686 del_timer_sync(&dlci->t1);
1687 dlci->gsm->dlci[dlci->addr] = NULL;
1688 kfifo_free(dlci->fifo);
1689 while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
1690 dev_kfree_skb(dlci->skb);
1694 static inline void dlci_get(struct gsm_dlci *dlci)
1696 tty_port_get(&dlci->port);
1699 static inline void dlci_put(struct gsm_dlci *dlci)
1701 tty_port_put(&dlci->port);
1704 static void gsm_destroy_network(struct gsm_dlci *dlci);
1707 * gsm_dlci_release - release DLCI
1708 * @dlci: DLCI to destroy
1710 * Release a DLCI. Actual free is deferred until either
1711 * mux is closed or tty is closed - whichever is last.
1715 static void gsm_dlci_release(struct gsm_dlci *dlci)
1717 struct tty_struct *tty = tty_port_tty_get(&dlci->port);
1719 mutex_lock(&dlci->mutex);
1720 gsm_destroy_network(dlci);
1721 mutex_unlock(&dlci->mutex);
1725 tty_port_tty_set(&dlci->port, NULL);
1728 dlci->state = DLCI_CLOSED;
1733 * LAPBish link layer logic
1737 * gsm_queue - a GSM frame is ready to process
1738 * @gsm: pointer to our gsm mux
1740 * At this point in time a frame has arrived and been demangled from
1741 * the line encoding. All the differences between the encodings have
1742 * been handled below us and the frame is unpacked into the structures.
1743 * The fcs holds the header FCS but any data FCS must be added here.
1746 static void gsm_queue(struct gsm_mux *gsm)
1748 struct gsm_dlci *dlci;
1751 /* We have to sneak a look at the packet body to do the FCS.
1752 A somewhat layering violation in the spec */
1754 if ((gsm->control & ~PF) == UI)
1755 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
1756 if (gsm->encoding == 0) {
1757 /* WARNING: gsm->received_fcs is used for
1758 gsm->encoding = 0 only.
1759 In this case it contain the last piece of data
1760 required to generate final CRC */
1761 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
1763 if (gsm->fcs != GOOD_FCS) {
1766 pr_debug("BAD FCS %02x\n", gsm->fcs);
1769 address = gsm->address >> 1;
1770 if (address >= NUM_DLCI)
1773 cr = gsm->address & 1; /* C/R bit */
1775 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1777 cr ^= 1 - gsm->initiator; /* Flip so 1 always means command */
1778 dlci = gsm->dlci[address];
1780 switch (gsm->control) {
1785 dlci = gsm_dlci_alloc(gsm, address);
1789 gsm_response(gsm, address, DM);
1791 gsm_response(gsm, address, UA);
1792 gsm_dlci_open(dlci);
1798 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1799 gsm_response(gsm, address, DM);
1802 /* Real close complete */
1803 gsm_response(gsm, address, UA);
1804 gsm_dlci_close(dlci);
1808 if (cr == 0 || dlci == NULL)
1810 switch (dlci->state) {
1812 gsm_dlci_close(dlci);
1815 gsm_dlci_open(dlci);
1819 case DM: /* DM can be valid unsolicited */
1825 gsm_dlci_close(dlci);
1835 if (dlci == NULL || dlci->state != DLCI_OPEN) {
1836 gsm_command(gsm, address, DM|PF);
1839 dlci->data(dlci, gsm->buf, gsm->len);
1852 * gsm0_receive - perform processing for non-transparency
1853 * @gsm: gsm data for this ldisc instance
1856 * Receive bytes in gsm mode 0
1859 static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
1863 switch (gsm->state) {
1864 case GSM_SEARCH: /* SOF marker */
1865 if (c == GSM0_SOF) {
1866 gsm->state = GSM_ADDRESS;
1869 gsm->fcs = INIT_FCS;
1872 case GSM_ADDRESS: /* Address EA */
1873 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1874 if (gsm_read_ea(&gsm->address, c))
1875 gsm->state = GSM_CONTROL;
1877 case GSM_CONTROL: /* Control Byte */
1878 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1880 gsm->state = GSM_LEN0;
1882 case GSM_LEN0: /* Length EA */
1883 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1884 if (gsm_read_ea(&gsm->len, c)) {
1885 if (gsm->len > gsm->mru) {
1887 gsm->state = GSM_SEARCH;
1892 gsm->state = GSM_FCS;
1894 gsm->state = GSM_DATA;
1897 gsm->state = GSM_LEN1;
1900 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1902 gsm->len |= len << 7;
1903 if (gsm->len > gsm->mru) {
1905 gsm->state = GSM_SEARCH;
1910 gsm->state = GSM_FCS;
1912 gsm->state = GSM_DATA;
1914 case GSM_DATA: /* Data */
1915 gsm->buf[gsm->count++] = c;
1916 if (gsm->count == gsm->len)
1917 gsm->state = GSM_FCS;
1919 case GSM_FCS: /* FCS follows the packet */
1920 gsm->received_fcs = c;
1922 gsm->state = GSM_SSOF;
1925 if (c == GSM0_SOF) {
1926 gsm->state = GSM_SEARCH;
1934 * gsm1_receive - perform processing for non-transparency
1935 * @gsm: gsm data for this ldisc instance
1938 * Receive bytes in mode 1 (Advanced option)
1941 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
1943 if (c == GSM1_SOF) {
1944 /* EOF is only valid in frame if we have got to the data state
1945 and received at least one byte (the FCS) */
1946 if (gsm->state == GSM_DATA && gsm->count) {
1947 /* Extract the FCS */
1949 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
1950 gsm->len = gsm->count;
1952 gsm->state = GSM_START;
1955 /* Any partial frame was a runt so go back to start */
1956 if (gsm->state != GSM_START) {
1958 gsm->state = GSM_START;
1960 /* A SOF in GSM_START means we are still reading idling or
1965 if (c == GSM1_ESCAPE) {
1970 /* Only an unescaped SOF gets us out of GSM search */
1971 if (gsm->state == GSM_SEARCH)
1975 c ^= GSM1_ESCAPE_BITS;
1978 switch (gsm->state) {
1979 case GSM_START: /* First byte after SOF */
1981 gsm->state = GSM_ADDRESS;
1982 gsm->fcs = INIT_FCS;
1984 case GSM_ADDRESS: /* Address continuation */
1985 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1986 if (gsm_read_ea(&gsm->address, c))
1987 gsm->state = GSM_CONTROL;
1989 case GSM_CONTROL: /* Control Byte */
1990 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1993 gsm->state = GSM_DATA;
1995 case GSM_DATA: /* Data */
1996 if (gsm->count > gsm->mru) { /* Allow one for the FCS */
1997 gsm->state = GSM_OVERRUN;
2000 gsm->buf[gsm->count++] = c;
2002 case GSM_OVERRUN: /* Over-long - eg a dropped SOF */
2008 * gsm_error - handle tty error
2010 * @data: byte received (may be invalid)
2011 * @flag: error received
2013 * Handle an error in the receipt of data for a frame. Currently we just
2014 * go back to hunting for a SOF.
2016 * FIXME: better diagnostics ?
2019 static void gsm_error(struct gsm_mux *gsm,
2020 unsigned char data, unsigned char flag)
2022 gsm->state = GSM_SEARCH;
2026 static int gsm_disconnect(struct gsm_mux *gsm)
2028 struct gsm_dlci *dlci = gsm->dlci[0];
2029 struct gsm_control *gc;
2034 /* In theory disconnecting DLCI 0 is sufficient but for some
2035 modems this is apparently not the case. */
2036 gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
2038 gsm_control_wait(gsm, gc);
2040 del_timer_sync(&gsm->t2_timer);
2041 /* Now we are sure T2 has stopped */
2043 gsm_dlci_begin_close(dlci);
2044 wait_event_interruptible(gsm->event,
2045 dlci->state == DLCI_CLOSED);
2047 if (signal_pending(current))
2054 * gsm_cleanup_mux - generic GSM protocol cleanup
2057 * Clean up the bits of the mux which are the same for all framing
2058 * protocols. Remove the mux from the mux table, stop all the timers
2059 * and then shut down each device hanging up the channels as we go.
2062 static void gsm_cleanup_mux(struct gsm_mux *gsm)
2065 struct gsm_dlci *dlci = gsm->dlci[0];
2066 struct gsm_msg *txq, *ntxq;
2070 spin_lock(&gsm_mux_lock);
2071 for (i = 0; i < MAX_MUX; i++) {
2072 if (gsm_mux[i] == gsm) {
2077 spin_unlock(&gsm_mux_lock);
2078 /* open failed before registering => nothing to do */
2082 del_timer_sync(&gsm->t2_timer);
2083 /* Now we are sure T2 has stopped */
2087 /* Free up any link layer users */
2088 mutex_lock(&gsm->mutex);
2089 for (i = 0; i < NUM_DLCI; i++)
2091 gsm_dlci_release(gsm->dlci[i]);
2092 mutex_unlock(&gsm->mutex);
2093 /* Now wipe the queues */
2094 list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2096 INIT_LIST_HEAD(&gsm->tx_list);
2100 * gsm_activate_mux - generic GSM setup
2103 * Set up the bits of the mux which are the same for all framing
2104 * protocols. Add the mux to the mux table so it can be opened and
2105 * finally kick off connecting to DLCI 0 on the modem.
2108 static int gsm_activate_mux(struct gsm_mux *gsm)
2110 struct gsm_dlci *dlci;
2113 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
2114 init_waitqueue_head(&gsm->event);
2115 spin_lock_init(&gsm->control_lock);
2116 spin_lock_init(&gsm->tx_lock);
2118 if (gsm->encoding == 0)
2119 gsm->receive = gsm0_receive;
2121 gsm->receive = gsm1_receive;
2122 gsm->error = gsm_error;
2124 spin_lock(&gsm_mux_lock);
2125 for (i = 0; i < MAX_MUX; i++) {
2126 if (gsm_mux[i] == NULL) {
2132 spin_unlock(&gsm_mux_lock);
2136 dlci = gsm_dlci_alloc(gsm, 0);
2139 gsm->dead = 0; /* Tty opens are now permissible */
2144 * gsm_free_mux - free up a mux
2147 * Dispose of allocated resources for a dead mux
2149 static void gsm_free_mux(struct gsm_mux *gsm)
2151 kfree(gsm->txframe);
2157 * gsm_free_muxr - free up a mux
2160 * Dispose of allocated resources for a dead mux
2162 static void gsm_free_muxr(struct kref *ref)
2164 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2168 static inline void mux_get(struct gsm_mux *gsm)
2170 kref_get(&gsm->ref);
2173 static inline void mux_put(struct gsm_mux *gsm)
2175 kref_put(&gsm->ref, gsm_free_muxr);
2178 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
2180 return gsm->num * NUM_DLCI;
2183 static inline unsigned int mux_line_to_num(unsigned int line)
2185 return line / NUM_DLCI;
2189 * gsm_alloc_mux - allocate a mux
2191 * Creates a new mux ready for activation.
2194 static struct gsm_mux *gsm_alloc_mux(void)
2196 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2199 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2200 if (gsm->buf == NULL) {
2204 gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
2205 if (gsm->txframe == NULL) {
2210 spin_lock_init(&gsm->lock);
2211 mutex_init(&gsm->mutex);
2212 kref_init(&gsm->ref);
2213 INIT_LIST_HEAD(&gsm->tx_list);
2221 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
2223 gsm->dead = 1; /* Avoid early tty opens */
2228 static void gsm_copy_config_values(struct gsm_mux *gsm,
2229 struct gsm_config *c)
2231 memset(c, 0, sizeof(*c));
2232 c->adaption = gsm->adaption;
2233 c->encapsulation = gsm->encoding;
2234 c->initiator = gsm->initiator;
2237 c->t3 = 0; /* Not supported */
2239 if (gsm->ftype == UIH)
2243 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
2249 static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
2252 int need_restart = 0;
2254 /* Stuff we don't support yet - UI or I frame transport, windowing */
2255 if ((c->adaption != 1 && c->adaption != 2) || c->k)
2257 /* Check the MRU/MTU range looks sane */
2258 if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2262 if (c->encapsulation > 1) /* Basic, advanced, no I */
2264 if (c->initiator > 1)
2266 if (c->i == 0 || c->i > 2) /* UIH and UI only */
2269 * See what is needed for reconfiguration
2273 if (c->t1 != 0 && c->t1 != gsm->t1)
2275 if (c->t2 != 0 && c->t2 != gsm->t2)
2277 if (c->encapsulation != gsm->encoding)
2279 if (c->adaption != gsm->adaption)
2282 if (c->initiator != gsm->initiator)
2284 if (c->mru != gsm->mru)
2286 if (c->mtu != gsm->mtu)
2290 * Close down what is needed, restart and initiate the new
2294 if (need_close || need_restart) {
2297 ret = gsm_disconnect(gsm);
2303 gsm_cleanup_mux(gsm);
2305 gsm->initiator = c->initiator;
2308 gsm->encoding = c->encapsulation;
2309 gsm->adaption = c->adaption;
2323 * FIXME: We need to separate activation/deactivation from adding
2324 * and removing from the mux array
2327 gsm_activate_mux(gsm);
2328 if (gsm->initiator && need_close)
2329 gsm_dlci_begin_open(gsm->dlci[0]);
2334 * gsmld_output - write to link
2336 * @data: bytes to output
2339 * Write a block of data from the GSM mux to the data channel. This
2340 * will eventually be serialized from above but at the moment isn't.
2343 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2345 if (tty_write_room(gsm->tty) < len) {
2346 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2350 print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET,
2352 gsm->tty->ops->write(gsm->tty, data, len);
2357 * gsmld_attach_gsm - mode set up
2358 * @tty: our tty structure
2361 * Set up the MUX for basic mode and commence connecting to the
2362 * modem. Currently called from the line discipline set up but
2363 * will need moving to an ioctl path.
2366 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2371 gsm->tty = tty_kref_get(tty);
2372 gsm->output = gsmld_output;
2373 ret = gsm_activate_mux(gsm);
2375 tty_kref_put(gsm->tty);
2377 /* Don't register device 0 - this is the control channel and not
2378 a usable tty interface */
2379 base = mux_num_to_base(gsm); /* Base for this MUX */
2380 for (i = 1; i < NUM_DLCI; i++)
2381 tty_register_device(gsm_tty_driver, base + i, NULL);
2388 * gsmld_detach_gsm - stop doing 0710 mux
2389 * @tty: tty attached to the mux
2392 * Shutdown and then clean up the resources used by the line discipline
2395 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2397 unsigned int base = mux_num_to_base(gsm); /* Base for this MUX */
2400 WARN_ON(tty != gsm->tty);
2401 for (i = 1; i < NUM_DLCI; i++)
2402 tty_unregister_device(gsm_tty_driver, base + i);
2403 gsm_cleanup_mux(gsm);
2404 tty_kref_put(gsm->tty);
2408 static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2409 char *fp, int count)
2411 struct gsm_mux *gsm = tty->disc_data;
2412 const unsigned char *dp;
2415 char flags = TTY_NORMAL;
2418 print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
2421 for (i = count, dp = cp, f = fp; i; i--, dp++) {
2426 gsm->receive(gsm, *dp);
2432 gsm->error(gsm, *dp, flags);
2435 WARN_ONCE(1, "%s: unknown flag %d\n",
2436 tty_name(tty), flags);
2440 /* FASYNC if needed ? */
2441 /* If clogged call tty_throttle(tty); */
2445 * gsmld_flush_buffer - clean input queue
2446 * @tty: terminal device
2448 * Flush the input buffer. Called when the line discipline is
2449 * being closed, when the tty layer wants the buffer flushed (eg
2453 static void gsmld_flush_buffer(struct tty_struct *tty)
2458 * gsmld_close - close the ldisc for this tty
2461 * Called from the terminal layer when this line discipline is
2462 * being shut down, either because of a close or becsuse of a
2463 * discipline change. The function will not be called while other
2464 * ldisc methods are in progress.
2467 static void gsmld_close(struct tty_struct *tty)
2469 struct gsm_mux *gsm = tty->disc_data;
2471 gsmld_detach_gsm(tty, gsm);
2473 gsmld_flush_buffer(tty);
2474 /* Do other clean up here */
2479 * gsmld_open - open an ldisc
2480 * @tty: terminal to open
2482 * Called when this line discipline is being attached to the
2483 * terminal device. Can sleep. Called serialized so that no
2484 * other events will occur in parallel. No further open will occur
2488 static int gsmld_open(struct tty_struct *tty)
2490 struct gsm_mux *gsm;
2493 if (tty->ops->write == NULL)
2496 /* Attach our ldisc data */
2497 gsm = gsm_alloc_mux();
2501 tty->disc_data = gsm;
2502 tty->receive_room = 65536;
2504 /* Attach the initial passive connection */
2507 ret = gsmld_attach_gsm(tty, gsm);
2509 gsm_cleanup_mux(gsm);
2516 * gsmld_write_wakeup - asynchronous I/O notifier
2519 * Required for the ptys, serial driver etc. since processes
2520 * that attach themselves to the master and rely on ASYNC
2521 * IO must be woken up
2524 static void gsmld_write_wakeup(struct tty_struct *tty)
2526 struct gsm_mux *gsm = tty->disc_data;
2527 unsigned long flags;
2530 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2531 spin_lock_irqsave(&gsm->tx_lock, flags);
2532 gsm_data_kick(gsm, NULL);
2533 if (gsm->tx_bytes < TX_THRESH_LO) {
2534 gsm_dlci_data_sweep(gsm);
2536 spin_unlock_irqrestore(&gsm->tx_lock, flags);
2540 * gsmld_read - read function for tty
2542 * @file: file object
2543 * @buf: userspace buffer pointer
2546 * Perform reads for the line discipline. We are guaranteed that the
2547 * line discipline will not be closed under us but we may get multiple
2548 * parallel readers and must handle this ourselves. We may also get
2549 * a hangup. Always called in user context, may sleep.
2551 * This code must be sure never to sleep through a hangup.
2554 static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2555 unsigned char __user *buf, size_t nr)
2561 * gsmld_write - write function for tty
2563 * @file: file object
2564 * @buf: userspace buffer pointer
2567 * Called when the owner of the device wants to send a frame
2568 * itself (or some other control data). The data is transferred
2569 * as-is and must be properly framed and checksummed as appropriate
2570 * by userspace. Frames are either sent whole or not at all as this
2571 * avoids pain user side.
2574 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2575 const unsigned char *buf, size_t nr)
2577 int space = tty_write_room(tty);
2579 return tty->ops->write(tty, buf, nr);
2580 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2585 * gsmld_poll - poll method for N_GSM0710
2586 * @tty: terminal device
2587 * @file: file accessing it
2590 * Called when the line discipline is asked to poll() for data or
2591 * for special events. This code is not serialized with respect to
2592 * other events save open/close.
2594 * This code must be sure never to sleep through a hangup.
2595 * Called without the kernel lock held - fine
2598 static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
2602 struct gsm_mux *gsm = tty->disc_data;
2604 poll_wait(file, &tty->read_wait, wait);
2605 poll_wait(file, &tty->write_wait, wait);
2606 if (tty_hung_up_p(file))
2608 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2609 mask |= EPOLLOUT | EPOLLWRNORM;
2615 static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
2616 unsigned int cmd, unsigned long arg)
2618 struct gsm_config c;
2619 struct gsm_mux *gsm = tty->disc_data;
2623 case GSMIOC_GETCONF:
2624 gsm_copy_config_values(gsm, &c);
2625 if (copy_to_user((void *)arg, &c, sizeof(c)))
2628 case GSMIOC_SETCONF:
2629 if (copy_from_user(&c, (void *)arg, sizeof(c)))
2631 return gsm_config(gsm, &c);
2632 case GSMIOC_GETFIRST:
2633 base = mux_num_to_base(gsm);
2634 return put_user(base + 1, (__u32 __user *)arg);
2636 return n_tty_ioctl_helper(tty, file, cmd, arg);
2645 static int gsm_mux_net_open(struct net_device *net)
2647 pr_debug("%s called\n", __func__);
2648 netif_start_queue(net);
2652 static int gsm_mux_net_close(struct net_device *net)
2654 netif_stop_queue(net);
2658 static void dlci_net_free(struct gsm_dlci *dlci)
2664 dlci->adaption = dlci->prev_adaption;
2665 dlci->data = dlci->prev_data;
2666 free_netdev(dlci->net);
2669 static void net_free(struct kref *ref)
2671 struct gsm_mux_net *mux_net;
2672 struct gsm_dlci *dlci;
2674 mux_net = container_of(ref, struct gsm_mux_net, ref);
2675 dlci = mux_net->dlci;
2678 unregister_netdev(dlci->net);
2679 dlci_net_free(dlci);
2683 static inline void muxnet_get(struct gsm_mux_net *mux_net)
2685 kref_get(&mux_net->ref);
2688 static inline void muxnet_put(struct gsm_mux_net *mux_net)
2690 kref_put(&mux_net->ref, net_free);
2693 static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
2694 struct net_device *net)
2696 struct gsm_mux_net *mux_net = netdev_priv(net);
2697 struct gsm_dlci *dlci = mux_net->dlci;
2698 muxnet_get(mux_net);
2700 skb_queue_head(&dlci->skb_list, skb);
2701 net->stats.tx_packets++;
2702 net->stats.tx_bytes += skb->len;
2703 gsm_dlci_data_kick(dlci);
2704 /* And tell the kernel when the last transmit started. */
2705 netif_trans_update(net);
2706 muxnet_put(mux_net);
2707 return NETDEV_TX_OK;
2710 /* called when a packet did not ack after watchdogtimeout */
2711 static void gsm_mux_net_tx_timeout(struct net_device *net)
2713 /* Tell syslog we are hosed. */
2714 dev_dbg(&net->dev, "Tx timed out.\n");
2716 /* Update statistics */
2717 net->stats.tx_errors++;
2720 static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2721 const unsigned char *in_buf, int size)
2723 struct net_device *net = dlci->net;
2724 struct sk_buff *skb;
2725 struct gsm_mux_net *mux_net = netdev_priv(net);
2726 muxnet_get(mux_net);
2728 /* Allocate an sk_buff */
2729 skb = dev_alloc_skb(size + NET_IP_ALIGN);
2731 /* We got no receive buffer. */
2732 net->stats.rx_dropped++;
2733 muxnet_put(mux_net);
2736 skb_reserve(skb, NET_IP_ALIGN);
2737 skb_put_data(skb, in_buf, size);
2740 skb->protocol = htons(ETH_P_IP);
2742 /* Ship it off to the kernel */
2745 /* update out statistics */
2746 net->stats.rx_packets++;
2747 net->stats.rx_bytes += size;
2748 muxnet_put(mux_net);
2752 static void gsm_mux_net_init(struct net_device *net)
2754 static const struct net_device_ops gsm_netdev_ops = {
2755 .ndo_open = gsm_mux_net_open,
2756 .ndo_stop = gsm_mux_net_close,
2757 .ndo_start_xmit = gsm_mux_net_start_xmit,
2758 .ndo_tx_timeout = gsm_mux_net_tx_timeout,
2761 net->netdev_ops = &gsm_netdev_ops;
2763 /* fill in the other fields */
2764 net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2765 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2766 net->type = ARPHRD_NONE;
2767 net->tx_queue_len = 10;
2771 /* caller holds the dlci mutex */
2772 static void gsm_destroy_network(struct gsm_dlci *dlci)
2774 struct gsm_mux_net *mux_net;
2776 pr_debug("destroy network interface");
2779 mux_net = netdev_priv(dlci->net);
2780 muxnet_put(mux_net);
2784 /* caller holds the dlci mutex */
2785 static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2789 struct net_device *net;
2790 struct gsm_mux_net *mux_net;
2792 if (!capable(CAP_NET_ADMIN))
2795 /* Already in a non tty mode */
2796 if (dlci->adaption > 2)
2799 if (nc->protocol != htons(ETH_P_IP))
2800 return -EPROTONOSUPPORT;
2802 if (nc->adaption != 3 && nc->adaption != 4)
2803 return -EPROTONOSUPPORT;
2805 pr_debug("create network interface");
2808 if (nc->if_name[0] != '\0')
2809 netname = nc->if_name;
2810 net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
2811 NET_NAME_UNKNOWN, gsm_mux_net_init);
2813 pr_err("alloc_netdev failed");
2816 net->mtu = dlci->gsm->mtu;
2818 net->max_mtu = dlci->gsm->mtu;
2819 mux_net = netdev_priv(net);
2820 mux_net->dlci = dlci;
2821 kref_init(&mux_net->ref);
2822 strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
2824 /* reconfigure dlci for network */
2825 dlci->prev_adaption = dlci->adaption;
2826 dlci->prev_data = dlci->data;
2827 dlci->adaption = nc->adaption;
2828 dlci->data = gsm_mux_rx_netchar;
2831 pr_debug("register netdev");
2832 retval = register_netdev(net);
2834 pr_err("network register fail %d\n", retval);
2835 dlci_net_free(dlci);
2838 return net->ifindex; /* return network index */
2841 /* Line discipline for real tty */
2842 static struct tty_ldisc_ops tty_ldisc_packet = {
2843 .owner = THIS_MODULE,
2844 .magic = TTY_LDISC_MAGIC,
2847 .close = gsmld_close,
2848 .flush_buffer = gsmld_flush_buffer,
2850 .write = gsmld_write,
2851 .ioctl = gsmld_ioctl,
2853 .receive_buf = gsmld_receive_buf,
2854 .write_wakeup = gsmld_write_wakeup
2863 static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
2866 struct gsm_control *ctrl;
2872 modembits[0] = len << 1 | EA; /* Data bytes */
2873 modembits[1] = dlci->addr << 2 | 3; /* DLCI, EA, 1 */
2874 modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
2876 modembits[3] = brk << 4 | 2 | EA; /* Valid, EA */
2877 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
2880 return gsm_control_wait(dlci->gsm, ctrl);
2883 static int gsm_carrier_raised(struct tty_port *port)
2885 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2886 struct gsm_mux *gsm = dlci->gsm;
2888 /* Not yet open so no carrier info */
2889 if (dlci->state != DLCI_OPEN)
2895 * Basic mode with control channel in ADM mode may not respond
2896 * to CMD_MSC at all and modem_rx is empty.
2898 if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
2902 return dlci->modem_rx & TIOCM_CD;
2905 static void gsm_dtr_rts(struct tty_port *port, int onoff)
2907 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2908 unsigned int modem_tx = dlci->modem_tx;
2910 modem_tx |= TIOCM_DTR | TIOCM_RTS;
2912 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
2913 if (modem_tx != dlci->modem_tx) {
2914 dlci->modem_tx = modem_tx;
2915 gsmtty_modem_update(dlci, 0);
2919 static const struct tty_port_operations gsm_port_ops = {
2920 .carrier_raised = gsm_carrier_raised,
2921 .dtr_rts = gsm_dtr_rts,
2922 .destruct = gsm_dlci_free,
2925 static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
2927 struct gsm_mux *gsm;
2928 struct gsm_dlci *dlci;
2929 unsigned int line = tty->index;
2930 unsigned int mux = mux_line_to_num(line);
2938 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
2939 if (gsm_mux[mux] == NULL)
2941 if (line == 0 || line > 61) /* 62/63 reserved */
2946 /* If DLCI 0 is not yet fully open return an error.
2947 This is ok from a locking
2948 perspective as we don't have to worry about this
2950 mutex_lock(&gsm->mutex);
2951 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
2952 mutex_unlock(&gsm->mutex);
2955 dlci = gsm->dlci[line];
2958 dlci = gsm_dlci_alloc(gsm, line);
2961 mutex_unlock(&gsm->mutex);
2964 ret = tty_port_install(&dlci->port, driver, tty);
2968 mutex_unlock(&gsm->mutex);
2973 dlci_get(gsm->dlci[0]);
2975 tty->driver_data = dlci;
2976 mutex_unlock(&gsm->mutex);
2981 static int gsmtty_open(struct tty_struct *tty, struct file *filp)
2983 struct gsm_dlci *dlci = tty->driver_data;
2984 struct tty_port *port = &dlci->port;
2987 tty_port_tty_set(port, tty);
2990 /* We could in theory open and close before we wait - eg if we get
2991 a DM straight back. This is ok as that will have caused a hangup */
2992 tty_port_set_initialized(port, 1);
2993 /* Start sending off SABM messages */
2994 gsm_dlci_begin_open(dlci);
2995 /* And wait for virtual carrier */
2996 return tty_port_block_til_ready(port, tty, filp);
2999 static void gsmtty_close(struct tty_struct *tty, struct file *filp)
3001 struct gsm_dlci *dlci = tty->driver_data;
3005 if (dlci->state == DLCI_CLOSED)
3007 mutex_lock(&dlci->mutex);
3008 gsm_destroy_network(dlci);
3009 mutex_unlock(&dlci->mutex);
3010 if (tty_port_close_start(&dlci->port, tty, filp) == 0)
3012 gsm_dlci_begin_close(dlci);
3013 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
3014 tty_port_lower_dtr_rts(&dlci->port);
3015 tty_port_close_end(&dlci->port, tty);
3016 tty_port_tty_set(&dlci->port, NULL);
3020 static void gsmtty_hangup(struct tty_struct *tty)
3022 struct gsm_dlci *dlci = tty->driver_data;
3023 if (dlci->state == DLCI_CLOSED)
3025 tty_port_hangup(&dlci->port);
3026 gsm_dlci_begin_close(dlci);
3029 static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
3033 struct gsm_dlci *dlci = tty->driver_data;
3034 if (dlci->state == DLCI_CLOSED)
3036 /* Stuff the bytes into the fifo queue */
3037 sent = kfifo_in_locked(dlci->fifo, buf, len, &dlci->lock);
3038 /* Need to kick the channel */
3039 gsm_dlci_data_kick(dlci);
3043 static int gsmtty_write_room(struct tty_struct *tty)
3045 struct gsm_dlci *dlci = tty->driver_data;
3046 if (dlci->state == DLCI_CLOSED)
3048 return TX_SIZE - kfifo_len(dlci->fifo);
3051 static int gsmtty_chars_in_buffer(struct tty_struct *tty)
3053 struct gsm_dlci *dlci = tty->driver_data;
3054 if (dlci->state == DLCI_CLOSED)
3056 return kfifo_len(dlci->fifo);
3059 static void gsmtty_flush_buffer(struct tty_struct *tty)
3061 struct gsm_dlci *dlci = tty->driver_data;
3062 if (dlci->state == DLCI_CLOSED)
3064 /* Caution needed: If we implement reliable transport classes
3065 then the data being transmitted can't simply be junked once
3066 it has first hit the stack. Until then we can just blow it
3068 kfifo_reset(dlci->fifo);
3069 /* Need to unhook this DLCI from the transmit queue logic */
3072 static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3074 /* The FIFO handles the queue so the kernel will do the right
3075 thing waiting on chars_in_buffer before calling us. No work
3079 static int gsmtty_tiocmget(struct tty_struct *tty)
3081 struct gsm_dlci *dlci = tty->driver_data;
3082 if (dlci->state == DLCI_CLOSED)
3084 return dlci->modem_rx;
3087 static int gsmtty_tiocmset(struct tty_struct *tty,
3088 unsigned int set, unsigned int clear)
3090 struct gsm_dlci *dlci = tty->driver_data;
3091 unsigned int modem_tx = dlci->modem_tx;
3093 if (dlci->state == DLCI_CLOSED)
3098 if (modem_tx != dlci->modem_tx) {
3099 dlci->modem_tx = modem_tx;
3100 return gsmtty_modem_update(dlci, 0);
3106 static int gsmtty_ioctl(struct tty_struct *tty,
3107 unsigned int cmd, unsigned long arg)
3109 struct gsm_dlci *dlci = tty->driver_data;
3110 struct gsm_netconfig nc;
3113 if (dlci->state == DLCI_CLOSED)
3116 case GSMIOC_ENABLE_NET:
3117 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3119 nc.if_name[IFNAMSIZ-1] = '\0';
3120 /* return net interface index or error code */
3121 mutex_lock(&dlci->mutex);
3122 index = gsm_create_network(dlci, &nc);
3123 mutex_unlock(&dlci->mutex);
3124 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3127 case GSMIOC_DISABLE_NET:
3128 if (!capable(CAP_NET_ADMIN))
3130 mutex_lock(&dlci->mutex);
3131 gsm_destroy_network(dlci);
3132 mutex_unlock(&dlci->mutex);
3135 return -ENOIOCTLCMD;
3139 static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3141 struct gsm_dlci *dlci = tty->driver_data;
3142 if (dlci->state == DLCI_CLOSED)
3144 /* For the moment its fixed. In actual fact the speed information
3145 for the virtual channel can be propogated in both directions by
3146 the RPN control message. This however rapidly gets nasty as we
3147 then have to remap modem signals each way according to whether
3148 our virtual cable is null modem etc .. */
3149 tty_termios_copy_hw(&tty->termios, old);
3152 static void gsmtty_throttle(struct tty_struct *tty)
3154 struct gsm_dlci *dlci = tty->driver_data;
3155 if (dlci->state == DLCI_CLOSED)
3158 dlci->modem_tx &= ~TIOCM_DTR;
3159 dlci->throttled = 1;
3160 /* Send an MSC with DTR cleared */
3161 gsmtty_modem_update(dlci, 0);
3164 static void gsmtty_unthrottle(struct tty_struct *tty)
3166 struct gsm_dlci *dlci = tty->driver_data;
3167 if (dlci->state == DLCI_CLOSED)
3170 dlci->modem_tx |= TIOCM_DTR;
3171 dlci->throttled = 0;
3172 /* Send an MSC with DTR set */
3173 gsmtty_modem_update(dlci, 0);
3176 static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3178 struct gsm_dlci *dlci = tty->driver_data;
3179 int encode = 0; /* Off */
3180 if (dlci->state == DLCI_CLOSED)
3183 if (state == -1) /* "On indefinitely" - we can't encode this
3186 else if (state > 0) {
3187 encode = state / 200; /* mS to encoding */
3189 encode = 0x0F; /* Best effort */
3191 return gsmtty_modem_update(dlci, encode);
3194 static void gsmtty_cleanup(struct tty_struct *tty)
3196 struct gsm_dlci *dlci = tty->driver_data;
3197 struct gsm_mux *gsm = dlci->gsm;
3200 dlci_put(gsm->dlci[0]);
3204 /* Virtual ttys for the demux */
3205 static const struct tty_operations gsmtty_ops = {
3206 .install = gsmtty_install,
3207 .open = gsmtty_open,
3208 .close = gsmtty_close,
3209 .write = gsmtty_write,
3210 .write_room = gsmtty_write_room,
3211 .chars_in_buffer = gsmtty_chars_in_buffer,
3212 .flush_buffer = gsmtty_flush_buffer,
3213 .ioctl = gsmtty_ioctl,
3214 .throttle = gsmtty_throttle,
3215 .unthrottle = gsmtty_unthrottle,
3216 .set_termios = gsmtty_set_termios,
3217 .hangup = gsmtty_hangup,
3218 .wait_until_sent = gsmtty_wait_until_sent,
3219 .tiocmget = gsmtty_tiocmget,
3220 .tiocmset = gsmtty_tiocmset,
3221 .break_ctl = gsmtty_break_ctl,
3222 .cleanup = gsmtty_cleanup,
3227 static int __init gsm_init(void)
3229 /* Fill in our line protocol discipline, and register it */
3230 int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
3232 pr_err("n_gsm: can't register line discipline (err = %d)\n",
3237 gsm_tty_driver = alloc_tty_driver(256);
3238 if (!gsm_tty_driver) {
3239 tty_unregister_ldisc(N_GSM0710);
3240 pr_err("gsm_init: tty allocation failed.\n");
3243 gsm_tty_driver->driver_name = "gsmtty";
3244 gsm_tty_driver->name = "gsmtty";
3245 gsm_tty_driver->major = 0; /* Dynamic */
3246 gsm_tty_driver->minor_start = 0;
3247 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
3248 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3249 gsm_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
3250 | TTY_DRIVER_HARDWARE_BREAK;
3251 gsm_tty_driver->init_termios = tty_std_termios;
3253 gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3254 tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3256 spin_lock_init(&gsm_mux_lock);
3258 if (tty_register_driver(gsm_tty_driver)) {
3259 put_tty_driver(gsm_tty_driver);
3260 tty_unregister_ldisc(N_GSM0710);
3261 pr_err("gsm_init: tty registration failed.\n");
3264 pr_debug("gsm_init: loaded as %d,%d.\n",
3265 gsm_tty_driver->major, gsm_tty_driver->minor_start);
3269 static void __exit gsm_exit(void)
3271 int status = tty_unregister_ldisc(N_GSM0710);
3273 pr_err("n_gsm: can't unregister line discipline (err = %d)\n",
3275 tty_unregister_driver(gsm_tty_driver);
3276 put_tty_driver(gsm_tty_driver);
3279 module_init(gsm_init);
3280 module_exit(gsm_exit);
3283 MODULE_LICENSE("GPL");
3284 MODULE_ALIAS_LDISC(N_GSM0710);