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>
56 module_param(debug, int, 0600);
58 /* Defaults: these are from the specification */
60 #define T1 10 /* 100mS */
61 #define T2 34 /* 333mS */
62 #define N2 3 /* Retry 3 times */
64 /* Use long timers for testing at low speed with debug on */
71 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
72 * limits so this is plenty
76 /* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */
77 #define PROT_OVERHEAD 7
78 #define GSM_NET_TX_TIMEOUT (HZ*10)
81 * struct gsm_mux_net - network interface
83 * Created when net interface is initialized.
87 struct gsm_dlci *dlci;
91 * Each block of data we have queued to go out is in the form of
92 * a gsm_msg which holds everything we need in a link layer independent
97 struct list_head list;
98 u8 addr; /* DLCI address + flags */
99 u8 ctrl; /* Control byte + flags */
100 unsigned int len; /* Length of data block (can be zero) */
101 unsigned char *data; /* Points into buffer but not at the start */
102 unsigned char buffer[];
105 enum gsm_dlci_state {
107 DLCI_OPENING, /* Sending SABM not seen UA */
108 DLCI_OPEN, /* SABM/UA complete */
109 DLCI_CLOSING, /* Sending DISC not seen UA/DM */
113 DLCI_MODE_ABM, /* Normal Asynchronous Balanced Mode */
114 DLCI_MODE_ADM, /* Asynchronous Disconnected Mode */
118 * Each active data link has a gsm_dlci structure associated which ties
119 * the link layer to an optional tty (if the tty side is open). To avoid
120 * complexity right now these are only ever freed up when the mux is
123 * At the moment we don't free DLCI objects until the mux is torn down
124 * this avoid object life time issues but might be worth review later.
130 enum gsm_dlci_state state;
134 enum gsm_dlci_mode mode;
135 spinlock_t lock; /* Protects the internal state */
136 struct timer_list t1; /* Retransmit timer for SABM and UA */
138 /* Uplink tty if active */
139 struct tty_port port; /* The tty bound to this DLCI if there is one */
140 #define TX_SIZE 4096 /* Must be power of 2. */
141 struct kfifo fifo; /* Queue fifo for the DLCI */
142 int adaption; /* Adaption layer in use */
144 u32 modem_rx; /* Our incoming virtual modem lines */
145 u32 modem_tx; /* Our outgoing modem lines */
146 bool dead; /* Refuse re-open */
148 bool throttled; /* Private copy of throttle state */
149 bool constipated; /* Throttle status for outgoing */
151 struct sk_buff *skb; /* Frame being sent */
152 struct sk_buff_head skb_list; /* Queued frames */
153 /* Data handling callback */
154 void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
155 void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
156 struct net_device *net; /* network interface, if created */
159 /* DLCI 0, 62/63 are special or reserved see gsmtty_open */
164 * DLCI 0 is used to pass control blocks out of band of the data
165 * flow (and with a higher link priority). One command can be outstanding
166 * at a time and we use this structure to manage them. They are created
167 * and destroyed by the user context, and updated by the receive paths
172 u8 cmd; /* Command we are issuing */
173 u8 *data; /* Data for the command in case we retransmit */
174 int len; /* Length of block for retransmission */
175 int done; /* Done flag */
176 int error; /* Error if any */
194 * Each GSM mux we have is represented by this structure. If we are
195 * operating as an ldisc then we use this structure as our ldisc
196 * state. We need to sort out lifetimes and locking with respect
197 * to the gsm mux array. For now we don't free DLCI objects that
198 * have been instantiated until the mux itself is terminated.
200 * To consider further: tty open versus mux shutdown.
204 struct tty_struct *tty; /* The tty our ldisc is bound to */
210 /* Events on the GSM channel */
211 wait_queue_head_t event;
213 /* Bits for GSM mode decoding */
217 enum gsm_mux_state state;
219 unsigned int address;
225 u8 *txframe; /* TX framing buffer */
227 /* Method for the receiver side */
228 void (*receive)(struct gsm_mux *gsm, u8 ch);
233 int initiator; /* Did we initiate connection */
234 bool dead; /* Has the mux been shut down */
235 struct gsm_dlci *dlci[NUM_DLCI];
236 int old_c_iflag; /* termios c_iflag value before attach */
237 bool constipated; /* Asked by remote to shut up */
240 unsigned int tx_bytes; /* TX data outstanding */
241 #define TX_THRESH_HI 8192
242 #define TX_THRESH_LO 2048
243 struct list_head tx_list; /* Pending data packets */
245 /* Control messages */
246 struct timer_list t2_timer; /* Retransmit timer for commands */
247 int cretries; /* Command retry counter */
248 struct gsm_control *pending_cmd;/* Our current pending command */
249 spinlock_t control_lock; /* Protects the pending command */
252 int adaption; /* 1 or 2 supported */
253 u8 ftype; /* UI or UIH */
254 int t1, t2; /* Timers in 1/100th of a sec */
255 int n2; /* Retry count */
257 /* Statistics (not currently exposed) */
258 unsigned long bad_fcs;
259 unsigned long malformed;
260 unsigned long io_error;
261 unsigned long bad_size;
262 unsigned long unsupported;
267 * Mux objects - needed so that we can translate a tty index into the
268 * relevant mux and DLCI.
271 #define MAX_MUX 4 /* 256 minors */
272 static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */
273 static DEFINE_SPINLOCK(gsm_mux_lock);
275 static struct tty_driver *gsm_tty_driver;
277 /* Save dlci open address */
278 static int addr_open[256] = { 0 };
279 /* Save dlci open count */
282 * This section of the driver logic implements the GSM encodings
283 * both the basic and the 'advanced'. Reliable transport is not
291 /* I is special: the rest are ..*/
302 /* Channel commands */
304 #define CMD_TEST 0x11
307 #define CMD_FCOFF 0x31
310 #define CMD_FCON 0x51
315 /* Virtual modem bits */
322 #define GSM0_SOF 0xF9
323 #define GSM1_SOF 0x7E
324 #define GSM1_ESCAPE 0x7D
325 #define GSM1_ESCAPE_BITS 0x20
328 #define ISO_IEC_646_MASK 0x7F
330 static const struct tty_port_operations gsm_port_ops;
333 * CRC table for GSM 0710
336 static const u8 gsm_fcs8[256] = {
337 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
338 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
339 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
340 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
341 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
342 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
343 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
344 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
345 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
346 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
347 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
348 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
349 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
350 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
351 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
352 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
353 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
354 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
355 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
356 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
357 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
358 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
359 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
360 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
361 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
362 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
363 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
364 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
365 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
366 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
367 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
368 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
371 #define INIT_FCS 0xFF
372 #define GOOD_FCS 0xCF
374 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
375 static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
378 * gsm_fcs_add - update FCS
382 * Update the FCS to include c. Uses the algorithm in the specification
386 static inline u8 gsm_fcs_add(u8 fcs, u8 c)
388 return gsm_fcs8[fcs ^ c];
392 * gsm_fcs_add_block - update FCS for a block
395 * @len: length of buffer
397 * Update the FCS to include c. Uses the algorithm in the specification
401 static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
404 fcs = gsm_fcs8[fcs ^ *c++];
409 * gsm_read_ea - read a byte into an EA
410 * @val: variable holding value
411 * @c: byte going into the EA
413 * Processes one byte of an EA. Updates the passed variable
414 * and returns 1 if the EA is now completely read
417 static int gsm_read_ea(unsigned int *val, u8 c)
419 /* Add the next 7 bits into the value */
422 /* Was this the last byte of the EA 1 = yes*/
427 * gsm_encode_modem - encode modem data bits
428 * @dlci: DLCI to encode from
430 * Returns the correct GSM encoded modem status bits (6 bit field) for
431 * the current status of the DLCI and attached tty object
434 static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
437 /* FC is true flow control not modem bits */
440 if (dlci->modem_tx & TIOCM_DTR)
441 modembits |= MDM_RTC;
442 if (dlci->modem_tx & TIOCM_RTS)
443 modembits |= MDM_RTR;
444 if (dlci->modem_tx & TIOCM_RI)
446 if (dlci->modem_tx & TIOCM_CD || dlci->gsm->initiator)
451 static void gsm_hex_dump_bytes(const char *fname, const u8 *data,
457 print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, data, len,
462 prefix = kasprintf(GFP_ATOMIC, "%s: ", fname);
465 print_hex_dump(KERN_INFO, prefix, DUMP_PREFIX_OFFSET, 16, 1, data, len,
471 * gsm_print_packet - display a frame for debug
472 * @hdr: header to print before decode
473 * @addr: address EA from the frame
474 * @cr: C/R bit seen as initiator
475 * @control: control including PF bit
476 * @data: following data bytes
477 * @dlen: length of data
479 * Displays a packet in human readable format for debugging purposes. The
480 * style is based on amateur radio LAP-B dump display.
483 static void gsm_print_packet(const char *hdr, int addr, int cr,
484 u8 control, const u8 *data, int dlen)
489 pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
491 switch (control & ~PF) {
511 if (!(control & 0x01)) {
512 pr_cont("I N(S)%d N(R)%d",
513 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
514 } else switch (control & 0x0F) {
516 pr_cont("RR(%d)", (control & 0xE0) >> 5);
519 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
522 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
525 pr_cont("[%02X]", control);
534 gsm_hex_dump_bytes(NULL, data, dlen);
539 * Link level transmission side
543 * gsm_stuff_frame - bytestuff a packet
544 * @input: input buffer
545 * @output: output buffer
546 * @len: length of input
548 * Expand a buffer by bytestuffing it. The worst case size change
549 * is doubling and the caller is responsible for handing out
550 * suitable sized buffers.
553 static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
557 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
558 || (*input & ISO_IEC_646_MASK) == XON
559 || (*input & ISO_IEC_646_MASK) == XOFF) {
560 *output++ = GSM1_ESCAPE;
561 *output++ = *input++ ^ GSM1_ESCAPE_BITS;
564 *output++ = *input++;
571 * gsm_send - send a control frame
573 * @addr: address for control frame
574 * @cr: command/response bit seen as initiator
575 * @control: control byte including PF bit
577 * Format up and transmit a control frame. These do not go via the
578 * queueing logic as they should be transmitted ahead of data when
581 * FIXME: Lock versus data TX path
584 static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
591 /* toggle C/R coding if not initiator */
592 ocr = cr ^ (gsm->initiator ? 0 : 1);
594 switch (gsm->encoding) {
597 cbuf[1] = (addr << 2) | (ocr << 1) | EA;
599 cbuf[3] = EA; /* Length of data = 0 */
600 cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
606 /* Control frame + packing (but not frame stuffing) in mode 1 */
607 ibuf[0] = (addr << 2) | (ocr << 1) | EA;
609 ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
610 /* Stuffing may double the size worst case */
611 len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
612 /* Now add the SOF markers */
614 cbuf[len + 1] = GSM1_SOF;
615 /* FIXME: we can omit the lead one in many cases */
622 gsmld_output(gsm, cbuf, len);
623 gsm_print_packet("-->", addr, cr, control, NULL, 0);
627 * gsm_response - send a control response
629 * @addr: address for control frame
630 * @control: control byte including PF bit
632 * Format up and transmit a link level response frame.
635 static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
637 gsm_send(gsm, addr, 0, control);
641 * gsm_command - send a control command
643 * @addr: address for control frame
644 * @control: control byte including PF bit
646 * Format up and transmit a link level command frame.
649 static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
651 gsm_send(gsm, addr, 1, control);
654 /* Data transmission */
656 #define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
659 * gsm_data_alloc - allocate data frame
661 * @addr: DLCI address
662 * @len: length excluding header and FCS
663 * @ctrl: control byte
665 * Allocate a new data buffer for sending frames with data. Space is left
666 * at the front for header bytes but that is treated as an implementation
667 * detail and not for the high level code to use
670 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
673 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
677 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */
681 INIT_LIST_HEAD(&m->list);
686 * gsm_data_kick - poke the queue
688 * @dlci: DLCI sending the data
690 * The tty device has called us to indicate that room has appeared in
691 * the transmit queue. Ram more data into the pipe if we have any
692 * If we have been flow-stopped by a CMD_FCOFF, then we can only
693 * send messages on DLCI0 until CMD_FCON
695 * FIXME: lock against link layer control transmissions
698 static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
700 struct gsm_msg *msg, *nmsg;
703 list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
704 if (gsm->constipated && msg->addr)
706 if (gsm->encoding != 0) {
707 gsm->txframe[0] = GSM1_SOF;
708 len = gsm_stuff_frame(msg->data,
709 gsm->txframe + 1, msg->len);
710 gsm->txframe[len + 1] = GSM1_SOF;
713 gsm->txframe[0] = GSM0_SOF;
714 memcpy(gsm->txframe + 1 , msg->data, msg->len);
715 gsm->txframe[msg->len + 1] = GSM0_SOF;
720 gsm_hex_dump_bytes(__func__, gsm->txframe, len);
721 if (gsmld_output(gsm, gsm->txframe, len) <= 0)
723 /* FIXME: Can eliminate one SOF in many more cases */
724 gsm->tx_bytes -= msg->len;
726 list_del(&msg->list);
730 tty_port_tty_wakeup(&dlci->port);
734 for (i = 0; i < NUM_DLCI; i++)
736 tty_port_tty_wakeup(&gsm->dlci[i]->port);
742 * __gsm_data_queue - queue a UI or UIH frame
743 * @dlci: DLCI sending the data
744 * @msg: message queued
746 * Add data to the transmit queue and try and get stuff moving
747 * out of the mux tty if not already doing so. The Caller must hold
751 static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
753 struct gsm_mux *gsm = dlci->gsm;
755 u8 *fcs = dp + msg->len;
757 /* Fill in the header */
758 if (gsm->encoding == 0) {
760 *--dp = (msg->len << 1) | EA;
762 *--dp = (msg->len >> 7); /* bits 7 - 15 */
763 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
769 *--dp = (msg->addr << 2) | 2 | EA;
771 *--dp = (msg->addr << 2) | EA;
772 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
773 /* Ugly protocol layering violation */
774 if (msg->ctrl == UI || msg->ctrl == (UI|PF))
775 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
778 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
779 msg->data, msg->len);
781 /* Move the header back and adjust the length, also allow for the FCS
782 now tacked on the end */
783 msg->len += (msg->data - dp) + 1;
786 /* Add to the actual output queue */
787 list_add_tail(&msg->list, &gsm->tx_list);
788 gsm->tx_bytes += msg->len;
789 gsm_data_kick(gsm, dlci);
793 * gsm_data_queue - queue a UI or UIH frame
794 * @dlci: DLCI sending the data
795 * @msg: message queued
797 * Add data to the transmit queue and try and get stuff moving
798 * out of the mux tty if not already doing so. Take the
799 * the gsm tx lock and dlci lock.
802 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
805 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
806 __gsm_data_queue(dlci, msg);
807 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
811 * gsm_dlci_data_output - try and push data out of a DLCI
813 * @dlci: the DLCI to pull data from
815 * Pull data from a DLCI and send it into the transmit queue if there
816 * is data. Keep to the MRU of the mux. This path handles the usual tty
817 * interface which is a byte stream with optional modem data.
819 * Caller must hold the tx_lock of the mux.
822 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
826 int len, total_size, size;
827 int h = dlci->adaption - 1;
831 len = kfifo_len(&dlci->fifo);
835 /* MTU/MRU count only the data bits */
841 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
842 /* FIXME: need a timer or something to kick this so it can't
843 get stuck with no work outstanding and no buffer free */
847 switch (dlci->adaption) {
848 case 1: /* Unstructured */
850 case 2: /* Unstructed with modem bits.
851 Always one byte as we never send inline break data */
852 *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
855 WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);
856 __gsm_data_queue(dlci, msg);
859 /* Bytes of data we used up */
864 * gsm_dlci_data_output_framed - try and push data out of a DLCI
866 * @dlci: the DLCI to pull data from
868 * Pull data from a DLCI and send it into the transmit queue if there
869 * is data. Keep to the MRU of the mux. This path handles framed data
870 * queued as skbuffs to the DLCI.
872 * Caller must hold the tx_lock of the mux.
875 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
876 struct gsm_dlci *dlci)
881 int last = 0, first = 0;
884 /* One byte per frame is used for B/F flags */
885 if (dlci->adaption == 4)
888 /* dlci->skb is locked by tx_lock */
889 if (dlci->skb == NULL) {
890 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
891 if (dlci->skb == NULL)
895 len = dlci->skb->len + overhead;
897 /* MTU/MRU count only the data bits */
898 if (len > gsm->mtu) {
899 if (dlci->adaption == 3) {
900 /* Over long frame, bin it */
901 dev_kfree_skb_any(dlci->skb);
909 size = len + overhead;
910 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
912 /* FIXME: need a timer or something to kick this so it can't
913 get stuck with no work outstanding and no buffer free */
915 skb_queue_tail(&dlci->skb_list, dlci->skb);
921 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
922 /* Flag byte to carry the start/end info */
923 *dp++ = last << 7 | first << 6 | 1; /* EA */
926 memcpy(dp, dlci->skb->data, len);
927 skb_pull(dlci->skb, len);
928 __gsm_data_queue(dlci, msg);
930 dev_kfree_skb_any(dlci->skb);
937 * gsm_dlci_modem_output - try and push modem status out of a DLCI
939 * @dlci: the DLCI to pull modem status from
942 * Push an empty frame in to the transmit queue to update the modem status
943 * bits and to transmit an optional break.
945 * Caller must hold the tx_lock of the mux.
948 static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
955 /* for modem bits without break data */
956 switch (dlci->adaption) {
957 case 1: /* Unstructured */
959 case 2: /* Unstructured with modem bits. */
965 pr_err("%s: unsupported adaption %d\n", __func__,
970 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
972 pr_err("%s: gsm_data_alloc error", __func__);
976 switch (dlci->adaption) {
977 case 1: /* Unstructured */
979 case 2: /* Unstructured with modem bits. */
981 *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
983 *dp++ = gsm_encode_modem(dlci) << 1;
984 *dp++ = (brk << 4) | 2 | EA; /* Length, Break, EA */
992 __gsm_data_queue(dlci, msg);
997 * gsm_dlci_data_sweep - look for data to send
1000 * Sweep the GSM mux channels in priority order looking for ones with
1001 * data to send. We could do with optimising this scan a bit. We aim
1002 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
1003 * TX_THRESH_LO we get called again
1005 * FIXME: We should round robin between groups and in theory you can
1006 * renegotiate DLCI priorities with optional stuff. Needs optimising.
1009 static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
1012 /* Priority ordering: We should do priority with RR of the groups */
1015 while (i < NUM_DLCI) {
1016 struct gsm_dlci *dlci;
1018 if (gsm->tx_bytes > TX_THRESH_HI)
1020 dlci = gsm->dlci[i];
1021 if (dlci == NULL || dlci->constipated) {
1025 if (dlci->adaption < 3 && !dlci->net)
1026 len = gsm_dlci_data_output(gsm, dlci);
1028 len = gsm_dlci_data_output_framed(gsm, dlci);
1031 /* DLCI empty - try the next */
1038 * gsm_dlci_data_kick - transmit if possible
1039 * @dlci: DLCI to kick
1041 * Transmit data from this DLCI if the queue is empty. We can't rely on
1042 * a tty wakeup except when we filled the pipe so we need to fire off
1043 * new data ourselves in other cases.
1046 static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
1048 unsigned long flags;
1051 if (dlci->constipated)
1054 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
1055 /* If we have nothing running then we need to fire up */
1056 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
1057 if (dlci->gsm->tx_bytes == 0) {
1059 gsm_dlci_data_output_framed(dlci->gsm, dlci);
1061 gsm_dlci_data_output(dlci->gsm, dlci);
1064 gsm_dlci_data_sweep(dlci->gsm);
1065 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
1069 * Control message processing
1074 * gsm_control_reply - send a response frame to a control
1076 * @cmd: the command to use
1077 * @data: data to follow encoded info
1078 * @dlen: length of data
1080 * Encode up and queue a UI/UIH frame containing our response.
1083 static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
1086 struct gsm_msg *msg;
1087 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
1090 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
1091 msg->data[1] = (dlen << 1) | EA;
1092 memcpy(msg->data + 2, data, dlen);
1093 gsm_data_queue(gsm->dlci[0], msg);
1097 * gsm_process_modem - process received modem status
1098 * @tty: virtual tty bound to the DLCI
1099 * @dlci: DLCI to affect
1100 * @modem: modem bits (full EA)
1101 * @slen: number of signal octets
1103 * Used when a modem control message or line state inline in adaption
1104 * layer 2 is processed. Sort out the local modem state and throttles
1107 static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1108 u32 modem, int slen)
1114 /* The modem status command can either contain one octet (V.24 signals)
1115 * or two octets (V.24 signals + break signals). This is specified in
1116 * section 5.4.6.3.7 of the 07.10 mux spec.
1120 modem = modem & 0x7f;
1123 modem = (modem >> 7) & 0x7f;
1126 /* Flow control/ready to communicate */
1127 fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1128 if (fc && !dlci->constipated) {
1129 /* Need to throttle our output on this device */
1130 dlci->constipated = true;
1131 } else if (!fc && dlci->constipated) {
1132 dlci->constipated = false;
1133 gsm_dlci_data_kick(dlci);
1136 /* Map modem bits */
1137 if (modem & MDM_RTC)
1138 mlines |= TIOCM_DSR | TIOCM_DTR;
1139 if (modem & MDM_RTR)
1140 mlines |= TIOCM_RTS | TIOCM_CTS;
1146 /* Carrier drop -> hangup */
1148 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1153 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1154 dlci->modem_rx = mlines;
1158 * gsm_control_modem - modem status received
1160 * @data: data following command
1161 * @clen: command length
1163 * We have received a modem status control message. This is used by
1164 * the GSM mux protocol to pass virtual modem line status and optionally
1165 * to indicate break signals. Unpack it, convert to Linux representation
1166 * and if need be stuff a break message down the tty.
1169 static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1171 unsigned int addr = 0;
1172 unsigned int modem = 0;
1173 struct gsm_dlci *dlci;
1176 const u8 *dp = data;
1177 struct tty_struct *tty;
1179 while (gsm_read_ea(&addr, *dp++) == 0) {
1184 /* Must be at least one byte following the EA */
1190 /* Closed port, or invalid ? */
1191 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1193 dlci = gsm->dlci[addr];
1196 while (gsm_read_ea(&modem, *dp++) == 0) {
1202 tty = tty_port_tty_get(&dlci->port);
1203 gsm_process_modem(tty, dlci, modem, slen - len);
1208 gsm_control_reply(gsm, CMD_MSC, data, clen);
1212 * gsm_control_rls - remote line status
1215 * @clen: data length
1217 * The modem sends us a two byte message on the control channel whenever
1218 * it wishes to send us an error state from the virtual link. Stuff
1219 * this into the uplink tty if present
1222 static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1224 struct tty_port *port;
1225 unsigned int addr = 0;
1228 const u8 *dp = data;
1230 while (gsm_read_ea(&addr, *dp++) == 0) {
1235 /* Must be at least one byte following ea */
1240 /* Closed port, or invalid ? */
1241 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1245 if ((bits & 1) == 0)
1248 port = &gsm->dlci[addr]->port;
1251 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1253 tty_insert_flip_char(port, 0, TTY_PARITY);
1255 tty_insert_flip_char(port, 0, TTY_FRAME);
1257 tty_flip_buffer_push(port);
1259 gsm_control_reply(gsm, CMD_RLS, data, clen);
1262 static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1263 static void gsm_dlci_close(struct gsm_dlci *dlci);
1266 * gsm_control_message - DLCI 0 control processing
1268 * @command: the command EA
1269 * @data: data beyond the command/length EAs
1272 * Input processor for control messages from the other end of the link.
1273 * Processes the incoming request and queues a response frame or an
1274 * NSC response if not supported
1277 static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1278 const u8 *data, int clen)
1281 unsigned long flags;
1282 struct gsm_dlci *dlci;
1289 for (i = 0; i < addr_cnt; i++) {
1290 address = addr_open[i];
1291 dlci = gsm->dlci[address];
1292 gsm_dlci_close(dlci);
1296 /* Modem wishes to close down */
1297 dlci = gsm->dlci[0];
1301 gsm_dlci_close(dlci);
1303 gsm_response(gsm, 0, UA|PF);
1308 /* Modem wishes to test, reply with the data */
1309 gsm_control_reply(gsm, CMD_TEST, data, clen);
1312 /* Modem can accept data again */
1313 gsm->constipated = false;
1314 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1315 /* Kick the link in case it is idling */
1316 spin_lock_irqsave(&gsm->tx_lock, flags);
1317 gsm_data_kick(gsm, NULL);
1318 spin_unlock_irqrestore(&gsm->tx_lock, flags);
1321 /* Modem wants us to STFU */
1322 gsm->constipated = true;
1323 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1326 /* Out of band modem line change indicator for a DLCI */
1327 gsm_control_modem(gsm, data, clen);
1330 /* Out of band error reception for a DLCI */
1331 gsm_control_rls(gsm, data, clen);
1334 /* Modem wishes to enter power saving state */
1335 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1337 /* Optional unsupported commands */
1338 case CMD_PN: /* Parameter negotiation */
1339 case CMD_RPN: /* Remote port negotiation */
1340 case CMD_SNC: /* Service negotiation command */
1342 /* Reply to bad commands with an NSC */
1344 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1350 * gsm_control_response - process a response to our control
1352 * @command: the command (response) EA
1353 * @data: data beyond the command/length EA
1356 * Process a response to an outstanding command. We only allow a single
1357 * control message in flight so this is fairly easy. All the clean up
1358 * is done by the caller, we just update the fields, flag it as done
1362 static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1363 const u8 *data, int clen)
1365 struct gsm_control *ctrl;
1366 unsigned long flags;
1368 spin_lock_irqsave(&gsm->control_lock, flags);
1370 ctrl = gsm->pending_cmd;
1371 /* Does the reply match our command */
1373 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1374 /* Our command was replied to, kill the retry timer */
1375 del_timer(&gsm->t2_timer);
1376 gsm->pending_cmd = NULL;
1377 /* Rejected by the other end */
1378 if (command == CMD_NSC)
1379 ctrl->error = -EOPNOTSUPP;
1381 wake_up(&gsm->event);
1383 spin_unlock_irqrestore(&gsm->control_lock, flags);
1387 * gsm_control_transmit - send control packet
1389 * @ctrl: frame to send
1391 * Send out a pending control command (called under control lock)
1394 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1396 struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 2, gsm->ftype);
1399 msg->data[0] = (ctrl->cmd << 1) | CR | EA; /* command */
1400 msg->data[1] = (ctrl->len << 1) | EA;
1401 memcpy(msg->data + 2, ctrl->data, ctrl->len);
1402 gsm_data_queue(gsm->dlci[0], msg);
1406 * gsm_control_retransmit - retransmit a control frame
1407 * @t: timer contained in our gsm object
1409 * Called off the T2 timer expiry in order to retransmit control frames
1410 * that have been lost in the system somewhere. The control_lock protects
1411 * us from colliding with another sender or a receive completion event.
1412 * In that situation the timer may still occur in a small window but
1413 * gsm->pending_cmd will be NULL and we just let the timer expire.
1416 static void gsm_control_retransmit(struct timer_list *t)
1418 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
1419 struct gsm_control *ctrl;
1420 unsigned long flags;
1421 spin_lock_irqsave(&gsm->control_lock, flags);
1422 ctrl = gsm->pending_cmd;
1424 if (gsm->cretries == 0) {
1425 gsm->pending_cmd = NULL;
1426 ctrl->error = -ETIMEDOUT;
1428 spin_unlock_irqrestore(&gsm->control_lock, flags);
1429 wake_up(&gsm->event);
1433 gsm_control_transmit(gsm, ctrl);
1434 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1436 spin_unlock_irqrestore(&gsm->control_lock, flags);
1440 * gsm_control_send - send a control frame on DLCI 0
1441 * @gsm: the GSM channel
1442 * @command: command to send including CR bit
1443 * @data: bytes of data (must be kmalloced)
1444 * @clen: length of the block to send
1446 * Queue and dispatch a control command. Only one command can be
1447 * active at a time. In theory more can be outstanding but the matching
1448 * gets really complicated so for now stick to one outstanding.
1451 static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1452 unsigned int command, u8 *data, int clen)
1454 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1456 unsigned long flags;
1460 wait_event(gsm->event, gsm->pending_cmd == NULL);
1461 spin_lock_irqsave(&gsm->control_lock, flags);
1462 if (gsm->pending_cmd != NULL) {
1463 spin_unlock_irqrestore(&gsm->control_lock, flags);
1466 ctrl->cmd = command;
1469 gsm->pending_cmd = ctrl;
1471 /* If DLCI0 is in ADM mode skip retries, it won't respond */
1472 if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
1475 gsm->cretries = gsm->n2;
1477 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1478 gsm_control_transmit(gsm, ctrl);
1479 spin_unlock_irqrestore(&gsm->control_lock, flags);
1484 * gsm_control_wait - wait for a control to finish
1486 * @control: control we are waiting on
1488 * Waits for the control to complete or time out. Frees any used
1489 * resources and returns 0 for success, or an error if the remote
1490 * rejected or ignored the request.
1493 static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
1496 wait_event(gsm->event, control->done == 1);
1497 err = control->error;
1504 * DLCI level handling: Needs krefs
1508 * State transitions and timers
1512 * gsm_dlci_close - a DLCI has closed
1513 * @dlci: DLCI that closed
1515 * Perform processing when moving a DLCI into closed state. If there
1516 * is an attached tty this is hung up
1519 static void gsm_dlci_close(struct gsm_dlci *dlci)
1521 unsigned long flags;
1523 del_timer(&dlci->t1);
1525 pr_debug("DLCI %d goes closed.\n", dlci->addr);
1526 dlci->state = DLCI_CLOSED;
1527 if (dlci->addr != 0) {
1528 tty_port_tty_hangup(&dlci->port, false);
1529 spin_lock_irqsave(&dlci->lock, flags);
1530 kfifo_reset(&dlci->fifo);
1531 spin_unlock_irqrestore(&dlci->lock, flags);
1532 /* Ensure that gsmtty_open() can return. */
1533 tty_port_set_initialized(&dlci->port, 0);
1534 wake_up_interruptible(&dlci->port.open_wait);
1536 dlci->gsm->dead = true;
1537 wake_up(&dlci->gsm->event);
1538 /* A DLCI 0 close is a MUX termination so we need to kick that
1539 back to userspace somehow */
1543 * gsm_dlci_open - a DLCI has opened
1544 * @dlci: DLCI that opened
1546 * Perform processing when moving a DLCI into open state.
1549 static void gsm_dlci_open(struct gsm_dlci *dlci)
1551 /* Note that SABM UA .. SABM UA first UA lost can mean that we go
1553 del_timer(&dlci->t1);
1554 /* This will let a tty open continue */
1555 dlci->state = DLCI_OPEN;
1557 pr_debug("DLCI %d goes open.\n", dlci->addr);
1558 /* Send current modem state */
1560 gsm_modem_update(dlci, 0);
1561 wake_up(&dlci->gsm->event);
1565 * gsm_dlci_t1 - T1 timer expiry
1566 * @t: timer contained in the DLCI that opened
1568 * The T1 timer handles retransmits of control frames (essentially of
1569 * SABM and DISC). We resend the command until the retry count runs out
1570 * in which case an opening port goes back to closed and a closing port
1571 * is simply put into closed state (any further frames from the other
1572 * end will get a DM response)
1574 * Some control dlci can stay in ADM mode with other dlci working just
1575 * fine. In that case we can just keep the control dlci open after the
1576 * DLCI_OPENING retries time out.
1579 static void gsm_dlci_t1(struct timer_list *t)
1581 struct gsm_dlci *dlci = from_timer(dlci, t, t1);
1582 struct gsm_mux *gsm = dlci->gsm;
1584 switch (dlci->state) {
1587 if (dlci->retries) {
1588 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1589 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1590 } else if (!dlci->addr && gsm->control == (DM | PF)) {
1592 pr_info("DLCI %d opening in ADM mode.\n",
1594 dlci->mode = DLCI_MODE_ADM;
1595 gsm_dlci_open(dlci);
1597 gsm_dlci_begin_close(dlci); /* prevent half open link */
1603 if (dlci->retries) {
1604 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1605 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1607 gsm_dlci_close(dlci);
1610 pr_debug("%s: unhandled state: %d\n", __func__, dlci->state);
1616 * gsm_dlci_begin_open - start channel open procedure
1617 * @dlci: DLCI to open
1619 * Commence opening a DLCI from the Linux side. We issue SABM messages
1620 * to the modem which should then reply with a UA or ADM, at which point
1621 * we will move into open state. Opening is done asynchronously with retry
1622 * running off timers and the responses.
1625 static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
1627 struct gsm_mux *gsm = dlci->gsm;
1628 if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING)
1630 dlci->retries = gsm->n2;
1631 dlci->state = DLCI_OPENING;
1632 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1633 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1637 * gsm_dlci_begin_close - start channel open procedure
1638 * @dlci: DLCI to open
1640 * Commence closing a DLCI from the Linux side. We issue DISC messages
1641 * to the modem which should then reply with a UA, at which point we
1642 * will move into closed state. Closing is done asynchronously with retry
1643 * off timers. We may also receive a DM reply from the other end which
1644 * indicates the channel was already closed.
1647 static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
1649 struct gsm_mux *gsm = dlci->gsm;
1650 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
1652 dlci->retries = gsm->n2;
1653 dlci->state = DLCI_CLOSING;
1654 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1655 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1659 * gsm_dlci_data - data arrived
1661 * @data: block of bytes received
1662 * @clen: length of received block
1664 * A UI or UIH frame has arrived which contains data for a channel
1665 * other than the control channel. If the relevant virtual tty is
1666 * open we shovel the bits down it, if not we drop them.
1669 static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
1672 struct tty_port *port = &dlci->port;
1673 struct tty_struct *tty;
1674 unsigned int modem = 0;
1679 pr_debug("%d bytes for tty\n", len);
1680 switch (dlci->adaption) {
1681 /* Unsupported types */
1682 case 4: /* Packetised interruptible data */
1684 case 3: /* Packetised uininterruptible voice/data */
1686 case 2: /* Asynchronous serial with line state in each frame */
1687 while (gsm_read_ea(&modem, *data++) == 0) {
1695 tty = tty_port_tty_get(port);
1697 gsm_process_modem(tty, dlci, modem, slen);
1702 case 1: /* Line state will go via DLCI 0 controls only */
1704 tty_insert_flip_string(port, data, len);
1705 tty_flip_buffer_push(port);
1710 * gsm_dlci_command - data arrived on control channel
1712 * @data: block of bytes received
1713 * @len: length of received block
1715 * A UI or UIH frame has arrived which contains data for DLCI 0 the
1716 * control channel. This should contain a command EA followed by
1717 * control data bytes. The command EA contains a command/response bit
1718 * and we divide up the work accordingly.
1721 static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
1723 /* See what command is involved */
1724 unsigned int command = 0;
1726 if (gsm_read_ea(&command, *data++) == 1) {
1729 /* FIXME: this is properly an EA */
1731 /* Malformed command ? */
1735 gsm_control_message(dlci->gsm, command,
1738 gsm_control_response(dlci->gsm, command,
1746 * Allocate/Free DLCI channels
1750 * gsm_dlci_alloc - allocate a DLCI
1752 * @addr: address of the DLCI
1754 * Allocate and install a new DLCI object into the GSM mux.
1756 * FIXME: review locking races
1759 static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
1761 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
1764 spin_lock_init(&dlci->lock);
1765 mutex_init(&dlci->mutex);
1766 if (kfifo_alloc(&dlci->fifo, TX_SIZE, GFP_KERNEL) < 0) {
1771 skb_queue_head_init(&dlci->skb_list);
1772 timer_setup(&dlci->t1, gsm_dlci_t1, 0);
1773 tty_port_init(&dlci->port);
1774 dlci->port.ops = &gsm_port_ops;
1777 dlci->adaption = gsm->adaption;
1778 dlci->state = DLCI_CLOSED;
1780 dlci->data = gsm_dlci_data;
1782 dlci->data = gsm_dlci_command;
1783 gsm->dlci[addr] = dlci;
1788 * gsm_dlci_free - free DLCI
1789 * @port: tty port for DLCI to free
1795 static void gsm_dlci_free(struct tty_port *port)
1797 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
1799 del_timer_sync(&dlci->t1);
1800 dlci->gsm->dlci[dlci->addr] = NULL;
1801 kfifo_free(&dlci->fifo);
1802 while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
1803 dev_kfree_skb(dlci->skb);
1807 static inline void dlci_get(struct gsm_dlci *dlci)
1809 tty_port_get(&dlci->port);
1812 static inline void dlci_put(struct gsm_dlci *dlci)
1814 tty_port_put(&dlci->port);
1817 static void gsm_destroy_network(struct gsm_dlci *dlci);
1820 * gsm_dlci_release - release DLCI
1821 * @dlci: DLCI to destroy
1823 * Release a DLCI. Actual free is deferred until either
1824 * mux is closed or tty is closed - whichever is last.
1828 static void gsm_dlci_release(struct gsm_dlci *dlci)
1830 struct tty_struct *tty = tty_port_tty_get(&dlci->port);
1832 mutex_lock(&dlci->mutex);
1833 gsm_destroy_network(dlci);
1834 mutex_unlock(&dlci->mutex);
1836 /* We cannot use tty_hangup() because in tty_kref_put() the tty
1837 * driver assumes that the hangup queue is free and reuses it to
1838 * queue release_one_tty() -> NULL pointer panic in
1839 * process_one_work().
1843 tty_port_tty_set(&dlci->port, NULL);
1846 dlci->state = DLCI_CLOSED;
1851 * LAPBish link layer logic
1855 * gsm_queue - a GSM frame is ready to process
1856 * @gsm: pointer to our gsm mux
1858 * At this point in time a frame has arrived and been demangled from
1859 * the line encoding. All the differences between the encodings have
1860 * been handled below us and the frame is unpacked into the structures.
1861 * The fcs holds the header FCS but any data FCS must be added here.
1864 static void gsm_queue(struct gsm_mux *gsm)
1866 struct gsm_dlci *dlci;
1869 int i, j, k, address_tmp;
1871 if (gsm->fcs != GOOD_FCS) {
1874 pr_debug("BAD FCS %02x\n", gsm->fcs);
1877 address = gsm->address >> 1;
1878 if (address >= NUM_DLCI)
1881 cr = gsm->address & 1; /* C/R bit */
1882 cr ^= gsm->initiator ? 0 : 1; /* Flip so 1 always means command */
1884 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1886 dlci = gsm->dlci[address];
1888 switch (gsm->control) {
1893 dlci = gsm_dlci_alloc(gsm, address);
1897 gsm_response(gsm, address, DM|PF);
1899 gsm_response(gsm, address, UA|PF);
1900 gsm_dlci_open(dlci);
1901 /* Save dlci open address */
1903 addr_open[addr_cnt] = address;
1911 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1912 gsm_response(gsm, address, DM|PF);
1915 /* Real close complete */
1918 for (i = 0; i < addr_cnt; i++) {
1919 address = addr_open[i];
1920 dlci = gsm->dlci[address];
1921 gsm_dlci_close(dlci);
1925 dlci = gsm->dlci[0];
1926 gsm_dlci_close(dlci);
1928 gsm_response(gsm, 0, UA|PF);
1930 gsm_response(gsm, address, UA|PF);
1931 gsm_dlci_close(dlci);
1932 /* clear dlci address */
1933 for (j = 0; j < addr_cnt; j++) {
1934 address_tmp = addr_open[j];
1935 if (address_tmp == address) {
1936 for (k = j; k < addr_cnt; k++)
1937 addr_open[k] = addr_open[k+1];
1945 if (cr == 0 || dlci == NULL)
1947 switch (dlci->state) {
1949 gsm_dlci_close(dlci);
1952 gsm_dlci_open(dlci);
1955 pr_debug("%s: unhandled state: %d\n", __func__,
1960 case DM: /* DM can be valid unsolicited */
1966 gsm_dlci_close(dlci);
1976 if (dlci == NULL || dlci->state != DLCI_OPEN) {
1977 gsm_command(gsm, address, DM|PF);
1980 dlci->data(dlci, gsm->buf, gsm->len);
1993 * gsm0_receive - perform processing for non-transparency
1994 * @gsm: gsm data for this ldisc instance
1997 * Receive bytes in gsm mode 0
2000 static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
2004 switch (gsm->state) {
2005 case GSM_SEARCH: /* SOF marker */
2006 if (c == GSM0_SOF) {
2007 gsm->state = GSM_ADDRESS;
2010 gsm->fcs = INIT_FCS;
2013 case GSM_ADDRESS: /* Address EA */
2014 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2015 if (gsm_read_ea(&gsm->address, c))
2016 gsm->state = GSM_CONTROL;
2018 case GSM_CONTROL: /* Control Byte */
2019 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2021 gsm->state = GSM_LEN0;
2023 case GSM_LEN0: /* Length EA */
2024 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2025 if (gsm_read_ea(&gsm->len, c)) {
2026 if (gsm->len > gsm->mru) {
2028 gsm->state = GSM_SEARCH;
2033 gsm->state = GSM_FCS;
2035 gsm->state = GSM_DATA;
2038 gsm->state = GSM_LEN1;
2041 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2043 gsm->len |= len << 7;
2044 if (gsm->len > gsm->mru) {
2046 gsm->state = GSM_SEARCH;
2051 gsm->state = GSM_FCS;
2053 gsm->state = GSM_DATA;
2055 case GSM_DATA: /* Data */
2056 gsm->buf[gsm->count++] = c;
2057 if (gsm->count == gsm->len) {
2058 /* Calculate final FCS for UI frames over all data */
2059 if ((gsm->control & ~PF) != UIH) {
2060 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
2063 gsm->state = GSM_FCS;
2066 case GSM_FCS: /* FCS follows the packet */
2067 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2068 gsm->state = GSM_SSOF;
2071 gsm->state = GSM_SEARCH;
2078 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2084 * gsm1_receive - perform processing for non-transparency
2085 * @gsm: gsm data for this ldisc instance
2088 * Receive bytes in mode 1 (Advanced option)
2091 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
2093 /* handle XON/XOFF */
2094 if ((c & ISO_IEC_646_MASK) == XON) {
2095 gsm->constipated = true;
2097 } else if ((c & ISO_IEC_646_MASK) == XOFF) {
2098 gsm->constipated = false;
2099 /* Kick the link in case it is idling */
2100 gsm_data_kick(gsm, NULL);
2103 if (c == GSM1_SOF) {
2104 /* EOF is only valid in frame if we have got to the data state */
2105 if (gsm->state == GSM_DATA) {
2106 if (gsm->count < 1) {
2109 gsm->state = GSM_START;
2112 /* Remove the FCS from data */
2114 if ((gsm->control & ~PF) != UIH) {
2115 /* Calculate final FCS for UI frames over all
2118 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
2121 /* Add the FCS itself to test against GOOD_FCS */
2122 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
2123 gsm->len = gsm->count;
2125 gsm->state = GSM_START;
2128 /* Any partial frame was a runt so go back to start */
2129 if (gsm->state != GSM_START) {
2130 if (gsm->state != GSM_SEARCH)
2132 gsm->state = GSM_START;
2134 /* A SOF in GSM_START means we are still reading idling or
2139 if (c == GSM1_ESCAPE) {
2144 /* Only an unescaped SOF gets us out of GSM search */
2145 if (gsm->state == GSM_SEARCH)
2149 c ^= GSM1_ESCAPE_BITS;
2150 gsm->escape = false;
2152 switch (gsm->state) {
2153 case GSM_START: /* First byte after SOF */
2155 gsm->state = GSM_ADDRESS;
2156 gsm->fcs = INIT_FCS;
2158 case GSM_ADDRESS: /* Address continuation */
2159 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2160 if (gsm_read_ea(&gsm->address, c))
2161 gsm->state = GSM_CONTROL;
2163 case GSM_CONTROL: /* Control Byte */
2164 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2167 gsm->state = GSM_DATA;
2169 case GSM_DATA: /* Data */
2170 if (gsm->count > gsm->mru) { /* Allow one for the FCS */
2171 gsm->state = GSM_OVERRUN;
2174 gsm->buf[gsm->count++] = c;
2176 case GSM_OVERRUN: /* Over-long - eg a dropped SOF */
2179 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2185 * gsm_error - handle tty error
2187 * @data: byte received (may be invalid)
2188 * @flag: error received
2190 * Handle an error in the receipt of data for a frame. Currently we just
2191 * go back to hunting for a SOF.
2193 * FIXME: better diagnostics ?
2196 static void gsm_error(struct gsm_mux *gsm,
2197 unsigned char data, unsigned char flag)
2199 gsm->state = GSM_SEARCH;
2204 * gsm_cleanup_mux - generic GSM protocol cleanup
2206 * @disc: disconnect link?
2208 * Clean up the bits of the mux which are the same for all framing
2209 * protocols. Remove the mux from the mux table, stop all the timers
2210 * and then shut down each device hanging up the channels as we go.
2213 static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
2216 struct gsm_dlci *dlci = gsm->dlci[0];
2217 struct gsm_msg *txq, *ntxq;
2220 mutex_lock(&gsm->mutex);
2223 if (disc && dlci->state != DLCI_CLOSED) {
2224 gsm_dlci_begin_close(dlci);
2225 wait_event(gsm->event, dlci->state == DLCI_CLOSED);
2230 /* Finish outstanding timers, making sure they are done */
2231 del_timer_sync(&gsm->t2_timer);
2233 /* Free up any link layer users and finally the control channel */
2234 for (i = NUM_DLCI - 1; i >= 0; i--)
2236 gsm_dlci_release(gsm->dlci[i]);
2237 mutex_unlock(&gsm->mutex);
2238 /* Now wipe the queues */
2239 tty_ldisc_flush(gsm->tty);
2240 list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2242 INIT_LIST_HEAD(&gsm->tx_list);
2246 * gsm_activate_mux - generic GSM setup
2249 * Set up the bits of the mux which are the same for all framing
2250 * protocols. Add the mux to the mux table so it can be opened and
2251 * finally kick off connecting to DLCI 0 on the modem.
2254 static int gsm_activate_mux(struct gsm_mux *gsm)
2256 struct gsm_dlci *dlci;
2258 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
2259 init_waitqueue_head(&gsm->event);
2260 spin_lock_init(&gsm->control_lock);
2261 spin_lock_init(&gsm->tx_lock);
2263 if (gsm->encoding == 0)
2264 gsm->receive = gsm0_receive;
2266 gsm->receive = gsm1_receive;
2268 dlci = gsm_dlci_alloc(gsm, 0);
2271 gsm->dead = false; /* Tty opens are now permissible */
2276 * gsm_free_mux - free up a mux
2279 * Dispose of allocated resources for a dead mux
2281 static void gsm_free_mux(struct gsm_mux *gsm)
2285 for (i = 0; i < MAX_MUX; i++) {
2286 if (gsm == gsm_mux[i]) {
2291 mutex_destroy(&gsm->mutex);
2292 kfree(gsm->txframe);
2298 * gsm_free_muxr - free up a mux
2299 * @ref: kreference to the mux to free
2301 * Dispose of allocated resources for a dead mux
2303 static void gsm_free_muxr(struct kref *ref)
2305 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2309 static inline void mux_get(struct gsm_mux *gsm)
2311 unsigned long flags;
2313 spin_lock_irqsave(&gsm_mux_lock, flags);
2314 kref_get(&gsm->ref);
2315 spin_unlock_irqrestore(&gsm_mux_lock, flags);
2318 static inline void mux_put(struct gsm_mux *gsm)
2320 unsigned long flags;
2322 spin_lock_irqsave(&gsm_mux_lock, flags);
2323 kref_put(&gsm->ref, gsm_free_muxr);
2324 spin_unlock_irqrestore(&gsm_mux_lock, flags);
2327 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
2329 return gsm->num * NUM_DLCI;
2332 static inline unsigned int mux_line_to_num(unsigned int line)
2334 return line / NUM_DLCI;
2338 * gsm_alloc_mux - allocate a mux
2340 * Creates a new mux ready for activation.
2343 static struct gsm_mux *gsm_alloc_mux(void)
2346 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2349 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2350 if (gsm->buf == NULL) {
2354 gsm->txframe = kmalloc(2 * (MAX_MTU + PROT_OVERHEAD - 1), GFP_KERNEL);
2355 if (gsm->txframe == NULL) {
2360 spin_lock_init(&gsm->lock);
2361 mutex_init(&gsm->mutex);
2362 kref_init(&gsm->ref);
2363 INIT_LIST_HEAD(&gsm->tx_list);
2371 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
2373 gsm->dead = true; /* Avoid early tty opens */
2375 /* Store the instance to the mux array or abort if no space is
2378 spin_lock(&gsm_mux_lock);
2379 for (i = 0; i < MAX_MUX; i++) {
2386 spin_unlock(&gsm_mux_lock);
2388 mutex_destroy(&gsm->mutex);
2389 kfree(gsm->txframe);
2398 static void gsm_copy_config_values(struct gsm_mux *gsm,
2399 struct gsm_config *c)
2401 memset(c, 0, sizeof(*c));
2402 c->adaption = gsm->adaption;
2403 c->encapsulation = gsm->encoding;
2404 c->initiator = gsm->initiator;
2407 c->t3 = 0; /* Not supported */
2409 if (gsm->ftype == UIH)
2413 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
2419 static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
2423 int need_restart = 0;
2425 /* Stuff we don't support yet - UI or I frame transport, windowing */
2426 if ((c->adaption != 1 && c->adaption != 2) || c->k)
2428 /* Check the MRU/MTU range looks sane */
2429 if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2433 if (c->encapsulation > 1) /* Basic, advanced, no I */
2435 if (c->initiator > 1)
2437 if (c->i == 0 || c->i > 2) /* UIH and UI only */
2440 * See what is needed for reconfiguration
2444 if (c->t1 != 0 && c->t1 != gsm->t1)
2446 if (c->t2 != 0 && c->t2 != gsm->t2)
2448 if (c->encapsulation != gsm->encoding)
2450 if (c->adaption != gsm->adaption)
2453 if (c->initiator != gsm->initiator)
2455 if (c->mru != gsm->mru)
2457 if (c->mtu != gsm->mtu)
2461 * Close down what is needed, restart and initiate the new
2462 * configuration. On the first time there is no DLCI[0]
2463 * and closing or cleaning up is not necessary.
2465 if (need_close || need_restart)
2466 gsm_cleanup_mux(gsm, true);
2468 gsm->initiator = c->initiator;
2471 gsm->encoding = c->encapsulation;
2472 gsm->adaption = c->adaption;
2486 * FIXME: We need to separate activation/deactivation from adding
2487 * and removing from the mux array
2490 ret = gsm_activate_mux(gsm);
2494 gsm_dlci_begin_open(gsm->dlci[0]);
2500 * gsmld_output - write to link
2502 * @data: bytes to output
2505 * Write a block of data from the GSM mux to the data channel. This
2506 * will eventually be serialized from above but at the moment isn't.
2509 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2511 if (tty_write_room(gsm->tty) < len) {
2512 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2516 gsm_hex_dump_bytes(__func__, data, len);
2517 return gsm->tty->ops->write(gsm->tty, data, len);
2521 * gsmld_attach_gsm - mode set up
2522 * @tty: our tty structure
2525 * Set up the MUX for basic mode and commence connecting to the
2526 * modem. Currently called from the line discipline set up but
2527 * will need moving to an ioctl path.
2530 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2535 gsm->tty = tty_kref_get(tty);
2536 /* Turn off tty XON/XOFF handling to handle it explicitly. */
2537 gsm->old_c_iflag = tty->termios.c_iflag;
2538 tty->termios.c_iflag &= (IXON | IXOFF);
2539 ret = gsm_activate_mux(gsm);
2541 tty_kref_put(gsm->tty);
2543 /* Don't register device 0 - this is the control channel and not
2544 a usable tty interface */
2545 base = mux_num_to_base(gsm); /* Base for this MUX */
2546 for (i = 1; i < NUM_DLCI; i++) {
2549 dev = tty_register_device(gsm_tty_driver,
2552 for (i--; i >= 1; i--)
2553 tty_unregister_device(gsm_tty_driver,
2555 return PTR_ERR(dev);
2564 * gsmld_detach_gsm - stop doing 0710 mux
2565 * @tty: tty attached to the mux
2568 * Shutdown and then clean up the resources used by the line discipline
2571 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2573 unsigned int base = mux_num_to_base(gsm); /* Base for this MUX */
2576 WARN_ON(tty != gsm->tty);
2577 for (i = 1; i < NUM_DLCI; i++)
2578 tty_unregister_device(gsm_tty_driver, base + i);
2579 /* Restore tty XON/XOFF handling. */
2580 gsm->tty->termios.c_iflag = gsm->old_c_iflag;
2581 tty_kref_put(gsm->tty);
2585 static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2586 const char *fp, int count)
2588 struct gsm_mux *gsm = tty->disc_data;
2589 char flags = TTY_NORMAL;
2592 gsm_hex_dump_bytes(__func__, cp, count);
2594 for (; count; count--, cp++) {
2599 gsm->receive(gsm, *cp);
2605 gsm_error(gsm, *cp, flags);
2608 WARN_ONCE(1, "%s: unknown flag %d\n",
2609 tty_name(tty), flags);
2613 /* FASYNC if needed ? */
2614 /* If clogged call tty_throttle(tty); */
2618 * gsmld_flush_buffer - clean input queue
2619 * @tty: terminal device
2621 * Flush the input buffer. Called when the line discipline is
2622 * being closed, when the tty layer wants the buffer flushed (eg
2626 static void gsmld_flush_buffer(struct tty_struct *tty)
2631 * gsmld_close - close the ldisc for this tty
2634 * Called from the terminal layer when this line discipline is
2635 * being shut down, either because of a close or becsuse of a
2636 * discipline change. The function will not be called while other
2637 * ldisc methods are in progress.
2640 static void gsmld_close(struct tty_struct *tty)
2642 struct gsm_mux *gsm = tty->disc_data;
2644 /* The ldisc locks and closes the port before calling our close. This
2645 * means we have no way to do a proper disconnect. We will not bother
2648 gsm_cleanup_mux(gsm, false);
2650 gsmld_detach_gsm(tty, gsm);
2652 gsmld_flush_buffer(tty);
2653 /* Do other clean up here */
2658 * gsmld_open - open an ldisc
2659 * @tty: terminal to open
2661 * Called when this line discipline is being attached to the
2662 * terminal device. Can sleep. Called serialized so that no
2663 * other events will occur in parallel. No further open will occur
2667 static int gsmld_open(struct tty_struct *tty)
2669 struct gsm_mux *gsm;
2672 if (tty->ops->write == NULL)
2675 /* Attach our ldisc data */
2676 gsm = gsm_alloc_mux();
2680 tty->disc_data = gsm;
2681 tty->receive_room = 65536;
2683 /* Attach the initial passive connection */
2686 ret = gsmld_attach_gsm(tty, gsm);
2688 gsm_cleanup_mux(gsm, false);
2695 * gsmld_write_wakeup - asynchronous I/O notifier
2698 * Required for the ptys, serial driver etc. since processes
2699 * that attach themselves to the master and rely on ASYNC
2700 * IO must be woken up
2703 static void gsmld_write_wakeup(struct tty_struct *tty)
2705 struct gsm_mux *gsm = tty->disc_data;
2706 unsigned long flags;
2709 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2710 spin_lock_irqsave(&gsm->tx_lock, flags);
2711 gsm_data_kick(gsm, NULL);
2712 if (gsm->tx_bytes < TX_THRESH_LO) {
2713 gsm_dlci_data_sweep(gsm);
2715 spin_unlock_irqrestore(&gsm->tx_lock, flags);
2719 * gsmld_read - read function for tty
2721 * @file: file object
2722 * @buf: userspace buffer pointer
2727 * Perform reads for the line discipline. We are guaranteed that the
2728 * line discipline will not be closed under us but we may get multiple
2729 * parallel readers and must handle this ourselves. We may also get
2730 * a hangup. Always called in user context, may sleep.
2732 * This code must be sure never to sleep through a hangup.
2735 static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2736 unsigned char *buf, size_t nr,
2737 void **cookie, unsigned long offset)
2743 * gsmld_write - write function for tty
2745 * @file: file object
2746 * @buf: userspace buffer pointer
2749 * Called when the owner of the device wants to send a frame
2750 * itself (or some other control data). The data is transferred
2751 * as-is and must be properly framed and checksummed as appropriate
2752 * by userspace. Frames are either sent whole or not at all as this
2753 * avoids pain user side.
2756 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2757 const unsigned char *buf, size_t nr)
2759 int space = tty_write_room(tty);
2761 return tty->ops->write(tty, buf, nr);
2762 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2767 * gsmld_poll - poll method for N_GSM0710
2768 * @tty: terminal device
2769 * @file: file accessing it
2772 * Called when the line discipline is asked to poll() for data or
2773 * for special events. This code is not serialized with respect to
2774 * other events save open/close.
2776 * This code must be sure never to sleep through a hangup.
2777 * Called without the kernel lock held - fine
2780 static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
2784 struct gsm_mux *gsm = tty->disc_data;
2786 poll_wait(file, &tty->read_wait, wait);
2787 poll_wait(file, &tty->write_wait, wait);
2788 if (tty_hung_up_p(file))
2790 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2791 mask |= EPOLLOUT | EPOLLWRNORM;
2797 static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
2798 unsigned int cmd, unsigned long arg)
2800 struct gsm_config c;
2801 struct gsm_mux *gsm = tty->disc_data;
2805 case GSMIOC_GETCONF:
2806 gsm_copy_config_values(gsm, &c);
2807 if (copy_to_user((void __user *)arg, &c, sizeof(c)))
2810 case GSMIOC_SETCONF:
2811 if (copy_from_user(&c, (void __user *)arg, sizeof(c)))
2813 return gsm_config(gsm, &c);
2814 case GSMIOC_GETFIRST:
2815 base = mux_num_to_base(gsm);
2816 return put_user(base + 1, (__u32 __user *)arg);
2818 return n_tty_ioctl_helper(tty, file, cmd, arg);
2827 static int gsm_mux_net_open(struct net_device *net)
2829 pr_debug("%s called\n", __func__);
2830 netif_start_queue(net);
2834 static int gsm_mux_net_close(struct net_device *net)
2836 netif_stop_queue(net);
2840 static void dlci_net_free(struct gsm_dlci *dlci)
2846 dlci->adaption = dlci->prev_adaption;
2847 dlci->data = dlci->prev_data;
2848 free_netdev(dlci->net);
2851 static void net_free(struct kref *ref)
2853 struct gsm_mux_net *mux_net;
2854 struct gsm_dlci *dlci;
2856 mux_net = container_of(ref, struct gsm_mux_net, ref);
2857 dlci = mux_net->dlci;
2860 unregister_netdev(dlci->net);
2861 dlci_net_free(dlci);
2865 static inline void muxnet_get(struct gsm_mux_net *mux_net)
2867 kref_get(&mux_net->ref);
2870 static inline void muxnet_put(struct gsm_mux_net *mux_net)
2872 kref_put(&mux_net->ref, net_free);
2875 static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
2876 struct net_device *net)
2878 struct gsm_mux_net *mux_net = netdev_priv(net);
2879 struct gsm_dlci *dlci = mux_net->dlci;
2880 muxnet_get(mux_net);
2882 skb_queue_head(&dlci->skb_list, skb);
2883 net->stats.tx_packets++;
2884 net->stats.tx_bytes += skb->len;
2885 gsm_dlci_data_kick(dlci);
2886 /* And tell the kernel when the last transmit started. */
2887 netif_trans_update(net);
2888 muxnet_put(mux_net);
2889 return NETDEV_TX_OK;
2892 /* called when a packet did not ack after watchdogtimeout */
2893 static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue)
2895 /* Tell syslog we are hosed. */
2896 dev_dbg(&net->dev, "Tx timed out.\n");
2898 /* Update statistics */
2899 net->stats.tx_errors++;
2902 static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2903 const unsigned char *in_buf, int size)
2905 struct net_device *net = dlci->net;
2906 struct sk_buff *skb;
2907 struct gsm_mux_net *mux_net = netdev_priv(net);
2908 muxnet_get(mux_net);
2910 /* Allocate an sk_buff */
2911 skb = dev_alloc_skb(size + NET_IP_ALIGN);
2913 /* We got no receive buffer. */
2914 net->stats.rx_dropped++;
2915 muxnet_put(mux_net);
2918 skb_reserve(skb, NET_IP_ALIGN);
2919 skb_put_data(skb, in_buf, size);
2922 skb->protocol = htons(ETH_P_IP);
2924 /* Ship it off to the kernel */
2927 /* update out statistics */
2928 net->stats.rx_packets++;
2929 net->stats.rx_bytes += size;
2930 muxnet_put(mux_net);
2934 static void gsm_mux_net_init(struct net_device *net)
2936 static const struct net_device_ops gsm_netdev_ops = {
2937 .ndo_open = gsm_mux_net_open,
2938 .ndo_stop = gsm_mux_net_close,
2939 .ndo_start_xmit = gsm_mux_net_start_xmit,
2940 .ndo_tx_timeout = gsm_mux_net_tx_timeout,
2943 net->netdev_ops = &gsm_netdev_ops;
2945 /* fill in the other fields */
2946 net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2947 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2948 net->type = ARPHRD_NONE;
2949 net->tx_queue_len = 10;
2953 /* caller holds the dlci mutex */
2954 static void gsm_destroy_network(struct gsm_dlci *dlci)
2956 struct gsm_mux_net *mux_net;
2958 pr_debug("destroy network interface\n");
2961 mux_net = netdev_priv(dlci->net);
2962 muxnet_put(mux_net);
2966 /* caller holds the dlci mutex */
2967 static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2971 struct net_device *net;
2972 struct gsm_mux_net *mux_net;
2974 if (!capable(CAP_NET_ADMIN))
2977 /* Already in a non tty mode */
2978 if (dlci->adaption > 2)
2981 if (nc->protocol != htons(ETH_P_IP))
2982 return -EPROTONOSUPPORT;
2984 if (nc->adaption != 3 && nc->adaption != 4)
2985 return -EPROTONOSUPPORT;
2987 pr_debug("create network interface\n");
2990 if (nc->if_name[0] != '\0')
2991 netname = nc->if_name;
2992 net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
2993 NET_NAME_UNKNOWN, gsm_mux_net_init);
2995 pr_err("alloc_netdev failed\n");
2998 net->mtu = dlci->gsm->mtu;
3000 net->max_mtu = dlci->gsm->mtu;
3001 mux_net = netdev_priv(net);
3002 mux_net->dlci = dlci;
3003 kref_init(&mux_net->ref);
3004 strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
3006 /* reconfigure dlci for network */
3007 dlci->prev_adaption = dlci->adaption;
3008 dlci->prev_data = dlci->data;
3009 dlci->adaption = nc->adaption;
3010 dlci->data = gsm_mux_rx_netchar;
3013 pr_debug("register netdev\n");
3014 retval = register_netdev(net);
3016 pr_err("network register fail %d\n", retval);
3017 dlci_net_free(dlci);
3020 return net->ifindex; /* return network index */
3023 /* Line discipline for real tty */
3024 static struct tty_ldisc_ops tty_ldisc_packet = {
3025 .owner = THIS_MODULE,
3029 .close = gsmld_close,
3030 .flush_buffer = gsmld_flush_buffer,
3032 .write = gsmld_write,
3033 .ioctl = gsmld_ioctl,
3035 .receive_buf = gsmld_receive_buf,
3036 .write_wakeup = gsmld_write_wakeup
3044 * gsm_modem_upd_via_data - send modem bits via convergence layer
3046 * @brk: break signal
3048 * Send an empty frame to signal mobile state changes and to transmit the
3049 * break signal for adaption 2.
3052 static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk)
3054 struct gsm_mux *gsm = dlci->gsm;
3055 unsigned long flags;
3057 if (dlci->state != DLCI_OPEN || dlci->adaption != 2)
3060 spin_lock_irqsave(&gsm->tx_lock, flags);
3061 gsm_dlci_modem_output(gsm, dlci, brk);
3062 spin_unlock_irqrestore(&gsm->tx_lock, flags);
3066 * gsm_modem_upd_via_msc - send modem bits via control frame
3068 * @brk: break signal
3071 static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk)
3074 struct gsm_control *ctrl;
3077 if (dlci->gsm->encoding != 0)
3080 modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */
3082 modembits[1] = (gsm_encode_modem(dlci) << 1) | EA;
3084 modembits[1] = gsm_encode_modem(dlci) << 1;
3085 modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */
3088 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len);
3091 return gsm_control_wait(dlci->gsm, ctrl);
3095 * gsm_modem_update - send modem status line state
3097 * @brk: break signal
3100 static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
3102 if (dlci->adaption == 2) {
3103 /* Send convergence layer type 2 empty data frame. */
3104 gsm_modem_upd_via_data(dlci, brk);
3106 } else if (dlci->gsm->encoding == 0) {
3107 /* Send as MSC control message. */
3108 return gsm_modem_upd_via_msc(dlci, brk);
3111 /* Modem status lines are not supported. */
3112 return -EPROTONOSUPPORT;
3115 static int gsm_carrier_raised(struct tty_port *port)
3117 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
3118 struct gsm_mux *gsm = dlci->gsm;
3120 /* Not yet open so no carrier info */
3121 if (dlci->state != DLCI_OPEN)
3127 * Basic mode with control channel in ADM mode may not respond
3128 * to CMD_MSC at all and modem_rx is empty.
3130 if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
3134 return dlci->modem_rx & TIOCM_CD;
3137 static void gsm_dtr_rts(struct tty_port *port, int onoff)
3139 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
3140 unsigned int modem_tx = dlci->modem_tx;
3142 modem_tx |= TIOCM_DTR | TIOCM_RTS;
3144 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
3145 if (modem_tx != dlci->modem_tx) {
3146 dlci->modem_tx = modem_tx;
3147 gsm_modem_update(dlci, 0);
3151 static const struct tty_port_operations gsm_port_ops = {
3152 .carrier_raised = gsm_carrier_raised,
3153 .dtr_rts = gsm_dtr_rts,
3154 .destruct = gsm_dlci_free,
3157 static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
3159 struct gsm_mux *gsm;
3160 struct gsm_dlci *dlci;
3161 unsigned int line = tty->index;
3162 unsigned int mux = mux_line_to_num(line);
3170 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
3171 if (gsm_mux[mux] == NULL)
3173 if (line == 0 || line > 61) /* 62/63 reserved */
3178 /* If DLCI 0 is not yet fully open return an error.
3179 This is ok from a locking
3180 perspective as we don't have to worry about this
3182 mutex_lock(&gsm->mutex);
3183 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
3184 mutex_unlock(&gsm->mutex);
3187 dlci = gsm->dlci[line];
3190 dlci = gsm_dlci_alloc(gsm, line);
3193 mutex_unlock(&gsm->mutex);
3196 ret = tty_port_install(&dlci->port, driver, tty);
3200 mutex_unlock(&gsm->mutex);
3205 dlci_get(gsm->dlci[0]);
3207 tty->driver_data = dlci;
3208 mutex_unlock(&gsm->mutex);
3213 static int gsmtty_open(struct tty_struct *tty, struct file *filp)
3215 struct gsm_dlci *dlci = tty->driver_data;
3216 struct tty_port *port = &dlci->port;
3219 tty_port_tty_set(port, tty);
3222 /* We could in theory open and close before we wait - eg if we get
3223 a DM straight back. This is ok as that will have caused a hangup */
3224 tty_port_set_initialized(port, 1);
3225 /* Start sending off SABM messages */
3226 gsm_dlci_begin_open(dlci);
3227 /* And wait for virtual carrier */
3228 return tty_port_block_til_ready(port, tty, filp);
3231 static void gsmtty_close(struct tty_struct *tty, struct file *filp)
3233 struct gsm_dlci *dlci = tty->driver_data;
3237 if (dlci->state == DLCI_CLOSED)
3239 mutex_lock(&dlci->mutex);
3240 gsm_destroy_network(dlci);
3241 mutex_unlock(&dlci->mutex);
3242 if (tty_port_close_start(&dlci->port, tty, filp) == 0)
3244 gsm_dlci_begin_close(dlci);
3245 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
3246 tty_port_lower_dtr_rts(&dlci->port);
3247 tty_port_close_end(&dlci->port, tty);
3248 tty_port_tty_set(&dlci->port, NULL);
3252 static void gsmtty_hangup(struct tty_struct *tty)
3254 struct gsm_dlci *dlci = tty->driver_data;
3255 if (dlci->state == DLCI_CLOSED)
3257 tty_port_hangup(&dlci->port);
3258 gsm_dlci_begin_close(dlci);
3261 static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
3265 struct gsm_dlci *dlci = tty->driver_data;
3266 if (dlci->state == DLCI_CLOSED)
3268 /* Stuff the bytes into the fifo queue */
3269 sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock);
3270 /* Need to kick the channel */
3271 gsm_dlci_data_kick(dlci);
3275 static unsigned int gsmtty_write_room(struct tty_struct *tty)
3277 struct gsm_dlci *dlci = tty->driver_data;
3278 if (dlci->state == DLCI_CLOSED)
3280 return kfifo_avail(&dlci->fifo);
3283 static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty)
3285 struct gsm_dlci *dlci = tty->driver_data;
3286 if (dlci->state == DLCI_CLOSED)
3288 return kfifo_len(&dlci->fifo);
3291 static void gsmtty_flush_buffer(struct tty_struct *tty)
3293 struct gsm_dlci *dlci = tty->driver_data;
3294 unsigned long flags;
3296 if (dlci->state == DLCI_CLOSED)
3298 /* Caution needed: If we implement reliable transport classes
3299 then the data being transmitted can't simply be junked once
3300 it has first hit the stack. Until then we can just blow it
3302 spin_lock_irqsave(&dlci->lock, flags);
3303 kfifo_reset(&dlci->fifo);
3304 spin_unlock_irqrestore(&dlci->lock, flags);
3305 /* Need to unhook this DLCI from the transmit queue logic */
3308 static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3310 /* The FIFO handles the queue so the kernel will do the right
3311 thing waiting on chars_in_buffer before calling us. No work
3315 static int gsmtty_tiocmget(struct tty_struct *tty)
3317 struct gsm_dlci *dlci = tty->driver_data;
3318 if (dlci->state == DLCI_CLOSED)
3320 return dlci->modem_rx;
3323 static int gsmtty_tiocmset(struct tty_struct *tty,
3324 unsigned int set, unsigned int clear)
3326 struct gsm_dlci *dlci = tty->driver_data;
3327 unsigned int modem_tx = dlci->modem_tx;
3329 if (dlci->state == DLCI_CLOSED)
3334 if (modem_tx != dlci->modem_tx) {
3335 dlci->modem_tx = modem_tx;
3336 return gsm_modem_update(dlci, 0);
3342 static int gsmtty_ioctl(struct tty_struct *tty,
3343 unsigned int cmd, unsigned long arg)
3345 struct gsm_dlci *dlci = tty->driver_data;
3346 struct gsm_netconfig nc;
3349 if (dlci->state == DLCI_CLOSED)
3352 case GSMIOC_ENABLE_NET:
3353 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3355 nc.if_name[IFNAMSIZ-1] = '\0';
3356 /* return net interface index or error code */
3357 mutex_lock(&dlci->mutex);
3358 index = gsm_create_network(dlci, &nc);
3359 mutex_unlock(&dlci->mutex);
3360 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3363 case GSMIOC_DISABLE_NET:
3364 if (!capable(CAP_NET_ADMIN))
3366 mutex_lock(&dlci->mutex);
3367 gsm_destroy_network(dlci);
3368 mutex_unlock(&dlci->mutex);
3371 return -ENOIOCTLCMD;
3375 static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3377 struct gsm_dlci *dlci = tty->driver_data;
3378 if (dlci->state == DLCI_CLOSED)
3380 /* For the moment its fixed. In actual fact the speed information
3381 for the virtual channel can be propogated in both directions by
3382 the RPN control message. This however rapidly gets nasty as we
3383 then have to remap modem signals each way according to whether
3384 our virtual cable is null modem etc .. */
3385 tty_termios_copy_hw(&tty->termios, old);
3388 static void gsmtty_throttle(struct tty_struct *tty)
3390 struct gsm_dlci *dlci = tty->driver_data;
3391 if (dlci->state == DLCI_CLOSED)
3394 dlci->modem_tx &= ~TIOCM_RTS;
3395 dlci->throttled = true;
3396 /* Send an MSC with RTS cleared */
3397 gsm_modem_update(dlci, 0);
3400 static void gsmtty_unthrottle(struct tty_struct *tty)
3402 struct gsm_dlci *dlci = tty->driver_data;
3403 if (dlci->state == DLCI_CLOSED)
3406 dlci->modem_tx |= TIOCM_RTS;
3407 dlci->throttled = false;
3408 /* Send an MSC with RTS set */
3409 gsm_modem_update(dlci, 0);
3412 static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3414 struct gsm_dlci *dlci = tty->driver_data;
3415 int encode = 0; /* Off */
3416 if (dlci->state == DLCI_CLOSED)
3419 if (state == -1) /* "On indefinitely" - we can't encode this
3422 else if (state > 0) {
3423 encode = state / 200; /* mS to encoding */
3425 encode = 0x0F; /* Best effort */
3427 return gsm_modem_update(dlci, encode);
3430 static void gsmtty_cleanup(struct tty_struct *tty)
3432 struct gsm_dlci *dlci = tty->driver_data;
3433 struct gsm_mux *gsm = dlci->gsm;
3436 dlci_put(gsm->dlci[0]);
3440 /* Virtual ttys for the demux */
3441 static const struct tty_operations gsmtty_ops = {
3442 .install = gsmtty_install,
3443 .open = gsmtty_open,
3444 .close = gsmtty_close,
3445 .write = gsmtty_write,
3446 .write_room = gsmtty_write_room,
3447 .chars_in_buffer = gsmtty_chars_in_buffer,
3448 .flush_buffer = gsmtty_flush_buffer,
3449 .ioctl = gsmtty_ioctl,
3450 .throttle = gsmtty_throttle,
3451 .unthrottle = gsmtty_unthrottle,
3452 .set_termios = gsmtty_set_termios,
3453 .hangup = gsmtty_hangup,
3454 .wait_until_sent = gsmtty_wait_until_sent,
3455 .tiocmget = gsmtty_tiocmget,
3456 .tiocmset = gsmtty_tiocmset,
3457 .break_ctl = gsmtty_break_ctl,
3458 .cleanup = gsmtty_cleanup,
3463 static int __init gsm_init(void)
3465 /* Fill in our line protocol discipline, and register it */
3466 int status = tty_register_ldisc(&tty_ldisc_packet);
3468 pr_err("n_gsm: can't register line discipline (err = %d)\n",
3473 gsm_tty_driver = tty_alloc_driver(256, TTY_DRIVER_REAL_RAW |
3474 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_HARDWARE_BREAK);
3475 if (IS_ERR(gsm_tty_driver)) {
3476 pr_err("gsm_init: tty allocation failed.\n");
3477 status = PTR_ERR(gsm_tty_driver);
3478 goto err_unreg_ldisc;
3480 gsm_tty_driver->driver_name = "gsmtty";
3481 gsm_tty_driver->name = "gsmtty";
3482 gsm_tty_driver->major = 0; /* Dynamic */
3483 gsm_tty_driver->minor_start = 0;
3484 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
3485 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3486 gsm_tty_driver->init_termios = tty_std_termios;
3488 gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3489 tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3491 if (tty_register_driver(gsm_tty_driver)) {
3492 pr_err("gsm_init: tty registration failed.\n");
3494 goto err_put_driver;
3496 pr_debug("gsm_init: loaded as %d,%d.\n",
3497 gsm_tty_driver->major, gsm_tty_driver->minor_start);
3500 tty_driver_kref_put(gsm_tty_driver);
3502 tty_unregister_ldisc(&tty_ldisc_packet);
3506 static void __exit gsm_exit(void)
3508 tty_unregister_ldisc(&tty_ldisc_packet);
3509 tty_unregister_driver(gsm_tty_driver);
3510 tty_driver_kref_put(gsm_tty_driver);
3513 module_init(gsm_init);
3514 module_exit(gsm_exit);
3517 MODULE_LICENSE("GPL");
3518 MODULE_ALIAS_LDISC(N_GSM0710);