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 #define GSM_NET_TX_TIMEOUT (HZ*10)
79 * struct gsm_mux_net - network interface
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[];
103 enum gsm_dlci_state {
105 DLCI_OPENING, /* Sending SABM not seen UA */
106 DLCI_OPEN, /* SABM/UA complete */
107 DLCI_CLOSING, /* Sending DISC not seen UA/DM */
111 DLCI_MODE_ABM, /* Normal Asynchronous Balanced Mode */
112 DLCI_MODE_ADM, /* Asynchronous Disconnected Mode */
116 * Each active data link has a gsm_dlci structure associated which ties
117 * the link layer to an optional tty (if the tty side is open). To avoid
118 * complexity right now these are only ever freed up when the mux is
121 * At the moment we don't free DLCI objects until the mux is torn down
122 * this avoid object life time issues but might be worth review later.
128 enum gsm_dlci_state state;
132 enum gsm_dlci_mode mode;
133 spinlock_t lock; /* Protects the internal state */
134 struct timer_list t1; /* Retransmit timer for SABM and UA */
136 /* Uplink tty if active */
137 struct tty_port port; /* The tty bound to this DLCI if there is one */
138 struct kfifo fifo; /* Queue fifo for the DLCI */
139 int adaption; /* Adaption layer in use */
141 u32 modem_rx; /* Our incoming virtual modem lines */
142 u32 modem_tx; /* Our outgoing modem lines */
143 bool dead; /* Refuse re-open */
145 bool throttled; /* Private copy of throttle state */
146 bool constipated; /* Throttle status for outgoing */
148 struct sk_buff *skb; /* Frame being sent */
149 struct sk_buff_head skb_list; /* Queued frames */
150 /* Data handling callback */
151 void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
152 void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
153 struct net_device *net; /* network interface, if created */
156 /* DLCI 0, 62/63 are special or reserved see gsmtty_open */
161 * DLCI 0 is used to pass control blocks out of band of the data
162 * flow (and with a higher link priority). One command can be outstanding
163 * at a time and we use this structure to manage them. They are created
164 * and destroyed by the user context, and updated by the receive paths
169 u8 cmd; /* Command we are issuing */
170 u8 *data; /* Data for the command in case we retransmit */
171 int len; /* Length of block for retransmission */
172 int done; /* Done flag */
173 int error; /* Error if any */
191 * Each GSM mux we have is represented by this structure. If we are
192 * operating as an ldisc then we use this structure as our ldisc
193 * state. We need to sort out lifetimes and locking with respect
194 * to the gsm mux array. For now we don't free DLCI objects that
195 * have been instantiated until the mux itself is terminated.
197 * To consider further: tty open versus mux shutdown.
201 struct tty_struct *tty; /* The tty our ldisc is bound to */
207 /* Events on the GSM channel */
208 wait_queue_head_t event;
210 /* Bits for GSM mode decoding */
214 enum gsm_mux_state state;
216 unsigned int address;
223 u8 *txframe; /* TX framing buffer */
225 /* Method for the receiver side */
226 void (*receive)(struct gsm_mux *gsm, u8 ch);
231 int initiator; /* Did we initiate connection */
232 bool dead; /* Has the mux been shut down */
233 struct gsm_dlci *dlci[NUM_DLCI];
234 bool constipated; /* Asked by remote to shut up */
237 unsigned int tx_bytes; /* TX data outstanding */
238 #define TX_THRESH_HI 8192
239 #define TX_THRESH_LO 2048
240 struct list_head tx_list; /* Pending data packets */
242 /* Control messages */
243 struct timer_list t2_timer; /* Retransmit timer for commands */
244 int cretries; /* Command retry counter */
245 struct gsm_control *pending_cmd;/* Our current pending command */
246 spinlock_t control_lock; /* Protects the pending command */
249 int adaption; /* 1 or 2 supported */
250 u8 ftype; /* UI or UIH */
251 int t1, t2; /* Timers in 1/100th of a sec */
252 int n2; /* Retry count */
254 /* Statistics (not currently exposed) */
255 unsigned long bad_fcs;
256 unsigned long malformed;
257 unsigned long io_error;
258 unsigned long bad_size;
259 unsigned long unsupported;
264 * Mux objects - needed so that we can translate a tty index into the
265 * relevant mux and DLCI.
268 #define MAX_MUX 4 /* 256 minors */
269 static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */
270 static DEFINE_SPINLOCK(gsm_mux_lock);
272 static struct tty_driver *gsm_tty_driver;
274 /* Save dlci open address */
275 static int addr_open[256] = { 0 };
276 /* Save dlci open count */
279 * This section of the driver logic implements the GSM encodings
280 * both the basic and the 'advanced'. Reliable transport is not
288 /* I is special: the rest are ..*/
299 /* Channel commands */
301 #define CMD_TEST 0x11
304 #define CMD_FCOFF 0x31
307 #define CMD_FCON 0x51
312 /* Virtual modem bits */
319 #define GSM0_SOF 0xF9
320 #define GSM1_SOF 0x7E
321 #define GSM1_ESCAPE 0x7D
322 #define GSM1_ESCAPE_BITS 0x20
325 #define ISO_IEC_646_MASK 0x7F
327 static const struct tty_port_operations gsm_port_ops;
330 * CRC table for GSM 0710
333 static const u8 gsm_fcs8[256] = {
334 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
335 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
336 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
337 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
338 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
339 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
340 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
341 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
342 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
343 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
344 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
345 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
346 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
347 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
348 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
349 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
350 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
351 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
352 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
353 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
354 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
355 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
356 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
357 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
358 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
359 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
360 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
361 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
362 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
363 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
364 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
365 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
368 #define INIT_FCS 0xFF
369 #define GOOD_FCS 0xCF
371 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
374 * gsm_fcs_add - update FCS
378 * Update the FCS to include c. Uses the algorithm in the specification
382 static inline u8 gsm_fcs_add(u8 fcs, u8 c)
384 return gsm_fcs8[fcs ^ c];
388 * gsm_fcs_add_block - update FCS for a block
391 * @len: length of buffer
393 * Update the FCS to include c. Uses the algorithm in the specification
397 static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
400 fcs = gsm_fcs8[fcs ^ *c++];
405 * gsm_read_ea - read a byte into an EA
406 * @val: variable holding value
407 * @c: byte going into the EA
409 * Processes one byte of an EA. Updates the passed variable
410 * and returns 1 if the EA is now completely read
413 static int gsm_read_ea(unsigned int *val, u8 c)
415 /* Add the next 7 bits into the value */
418 /* Was this the last byte of the EA 1 = yes*/
423 * gsm_encode_modem - encode modem data bits
424 * @dlci: DLCI to encode from
426 * Returns the correct GSM encoded modem status bits (6 bit field) for
427 * the current status of the DLCI and attached tty object
430 static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
433 /* FC is true flow control not modem bits */
436 if (dlci->modem_tx & TIOCM_DTR)
437 modembits |= MDM_RTC;
438 if (dlci->modem_tx & TIOCM_RTS)
439 modembits |= MDM_RTR;
440 if (dlci->modem_tx & TIOCM_RI)
442 if (dlci->modem_tx & TIOCM_CD)
448 * gsm_print_packet - display a frame for debug
449 * @hdr: header to print before decode
450 * @addr: address EA from the frame
451 * @cr: C/R bit from the frame
452 * @control: control including PF bit
453 * @data: following data bytes
454 * @dlen: length of data
456 * Displays a packet in human readable format for debugging purposes. The
457 * style is based on amateur radio LAP-B dump display.
460 static void gsm_print_packet(const char *hdr, int addr, int cr,
461 u8 control, const u8 *data, int dlen)
466 pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
468 switch (control & ~PF) {
488 if (!(control & 0x01)) {
489 pr_cont("I N(S)%d N(R)%d",
490 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
491 } else switch (control & 0x0F) {
493 pr_cont("RR(%d)", (control & 0xE0) >> 5);
496 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
499 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
502 pr_cont("[%02X]", control);
511 print_hex_dump_bytes("", DUMP_PREFIX_NONE, data, dlen);
516 * Link level transmission side
520 * gsm_stuff_frame - bytestuff a packet
521 * @input: input buffer
522 * @output: output buffer
523 * @len: length of input
525 * Expand a buffer by bytestuffing it. The worst case size change
526 * is doubling and the caller is responsible for handing out
527 * suitable sized buffers.
530 static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
534 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
535 || (*input & ISO_IEC_646_MASK) == XON
536 || (*input & ISO_IEC_646_MASK) == XOFF) {
537 *output++ = GSM1_ESCAPE;
538 *output++ = *input++ ^ GSM1_ESCAPE_BITS;
541 *output++ = *input++;
548 * gsm_send - send a control frame
550 * @addr: address for control frame
551 * @cr: command/response bit
552 * @control: control byte including PF bit
554 * Format up and transmit a control frame. These do not go via the
555 * queueing logic as they should be transmitted ahead of data when
558 * FIXME: Lock versus data TX path
561 static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
567 switch (gsm->encoding) {
570 cbuf[1] = (addr << 2) | (cr << 1) | EA;
572 cbuf[3] = EA; /* Length of data = 0 */
573 cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
579 /* Control frame + packing (but not frame stuffing) in mode 1 */
580 ibuf[0] = (addr << 2) | (cr << 1) | EA;
582 ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
583 /* Stuffing may double the size worst case */
584 len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
585 /* Now add the SOF markers */
587 cbuf[len + 1] = GSM1_SOF;
588 /* FIXME: we can omit the lead one in many cases */
595 gsmld_output(gsm, cbuf, len);
596 if (!gsm->initiator) {
597 cr = cr & gsm->initiator;
598 control = control & ~PF;
600 gsm_print_packet("-->", addr, cr, control, NULL, 0);
604 * gsm_response - send a control response
606 * @addr: address for control frame
607 * @control: control byte including PF bit
609 * Format up and transmit a link level response frame.
612 static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
614 gsm_send(gsm, addr, 1, control);
618 * gsm_command - send a control command
620 * @addr: address for control frame
621 * @control: control byte including PF bit
623 * Format up and transmit a link level command frame.
626 static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
628 gsm_send(gsm, addr, 1, control);
631 /* Data transmission */
633 #define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
636 * gsm_data_alloc - allocate data frame
638 * @addr: DLCI address
639 * @len: length excluding header and FCS
640 * @ctrl: control byte
642 * Allocate a new data buffer for sending frames with data. Space is left
643 * at the front for header bytes but that is treated as an implementation
644 * detail and not for the high level code to use
647 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
650 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
654 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */
658 INIT_LIST_HEAD(&m->list);
663 * gsm_data_kick - poke the queue
665 * @dlci: DLCI sending the data
667 * The tty device has called us to indicate that room has appeared in
668 * the transmit queue. Ram more data into the pipe if we have any
669 * If we have been flow-stopped by a CMD_FCOFF, then we can only
670 * send messages on DLCI0 until CMD_FCON
672 * FIXME: lock against link layer control transmissions
675 static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
677 struct gsm_msg *msg, *nmsg;
680 list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
681 if (gsm->constipated && msg->addr)
683 if (gsm->encoding != 0) {
684 gsm->txframe[0] = GSM1_SOF;
685 len = gsm_stuff_frame(msg->data,
686 gsm->txframe + 1, msg->len);
687 gsm->txframe[len + 1] = GSM1_SOF;
690 gsm->txframe[0] = GSM0_SOF;
691 memcpy(gsm->txframe + 1 , msg->data, msg->len);
692 gsm->txframe[msg->len + 1] = GSM0_SOF;
697 print_hex_dump_bytes("gsm_data_kick: ",
700 if (gsmld_output(gsm, gsm->txframe, len) <= 0)
702 /* FIXME: Can eliminate one SOF in many more cases */
703 gsm->tx_bytes -= msg->len;
705 list_del(&msg->list);
709 tty_port_tty_wakeup(&dlci->port);
713 for (i = 0; i < NUM_DLCI; i++)
715 tty_port_tty_wakeup(&gsm->dlci[i]->port);
721 * __gsm_data_queue - queue a UI or UIH frame
722 * @dlci: DLCI sending the data
723 * @msg: message queued
725 * Add data to the transmit queue and try and get stuff moving
726 * out of the mux tty if not already doing so. The Caller must hold
730 static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
732 struct gsm_mux *gsm = dlci->gsm;
734 u8 *fcs = dp + msg->len;
736 /* Fill in the header */
737 if (gsm->encoding == 0) {
739 *--dp = (msg->len << 1) | EA;
741 *--dp = (msg->len >> 7); /* bits 7 - 15 */
742 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
748 *--dp = (msg->addr << 2) | 2 | EA;
750 *--dp = (msg->addr << 2) | EA;
751 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
752 /* Ugly protocol layering violation */
753 if (msg->ctrl == UI || msg->ctrl == (UI|PF))
754 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
757 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
758 msg->data, msg->len);
760 /* Move the header back and adjust the length, also allow for the FCS
761 now tacked on the end */
762 msg->len += (msg->data - dp) + 1;
765 /* Add to the actual output queue */
766 list_add_tail(&msg->list, &gsm->tx_list);
767 gsm->tx_bytes += msg->len;
768 gsm_data_kick(gsm, dlci);
772 * gsm_data_queue - queue a UI or UIH frame
773 * @dlci: DLCI sending the data
774 * @msg: message queued
776 * Add data to the transmit queue and try and get stuff moving
777 * out of the mux tty if not already doing so. Take the
778 * the gsm tx lock and dlci lock.
781 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
784 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
785 __gsm_data_queue(dlci, msg);
786 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
790 * gsm_dlci_data_output - try and push data out of a DLCI
792 * @dlci: the DLCI to pull data from
794 * Pull data from a DLCI and send it into the transmit queue if there
795 * is data. Keep to the MRU of the mux. This path handles the usual tty
796 * interface which is a byte stream with optional modem data.
798 * Caller must hold the tx_lock of the mux.
801 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
805 int len, total_size, size;
806 int h = dlci->adaption - 1;
810 len = kfifo_len(&dlci->fifo);
814 /* MTU/MRU count only the data bits */
820 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
821 /* FIXME: need a timer or something to kick this so it can't
822 get stuck with no work outstanding and no buffer free */
826 switch (dlci->adaption) {
827 case 1: /* Unstructured */
829 case 2: /* Unstructed with modem bits.
830 Always one byte as we never send inline break data */
831 *dp++ = gsm_encode_modem(dlci);
834 WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);
835 __gsm_data_queue(dlci, msg);
838 /* Bytes of data we used up */
843 * gsm_dlci_data_output_framed - try and push data out of a DLCI
845 * @dlci: the DLCI to pull data from
847 * Pull data from a DLCI and send it into the transmit queue if there
848 * is data. Keep to the MRU of the mux. This path handles framed data
849 * queued as skbuffs to the DLCI.
851 * Caller must hold the tx_lock of the mux.
854 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
855 struct gsm_dlci *dlci)
860 int last = 0, first = 0;
863 /* One byte per frame is used for B/F flags */
864 if (dlci->adaption == 4)
867 /* dlci->skb is locked by tx_lock */
868 if (dlci->skb == NULL) {
869 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
870 if (dlci->skb == NULL)
874 len = dlci->skb->len + overhead;
876 /* MTU/MRU count only the data bits */
877 if (len > gsm->mtu) {
878 if (dlci->adaption == 3) {
879 /* Over long frame, bin it */
880 dev_kfree_skb_any(dlci->skb);
888 size = len + overhead;
889 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
891 /* FIXME: need a timer or something to kick this so it can't
892 get stuck with no work outstanding and no buffer free */
894 skb_queue_tail(&dlci->skb_list, dlci->skb);
900 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
901 /* Flag byte to carry the start/end info */
902 *dp++ = last << 7 | first << 6 | 1; /* EA */
905 memcpy(dp, dlci->skb->data, len);
906 skb_pull(dlci->skb, len);
907 __gsm_data_queue(dlci, msg);
909 dev_kfree_skb_any(dlci->skb);
916 * gsm_dlci_data_sweep - look for data to send
919 * Sweep the GSM mux channels in priority order looking for ones with
920 * data to send. We could do with optimising this scan a bit. We aim
921 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
922 * TX_THRESH_LO we get called again
924 * FIXME: We should round robin between groups and in theory you can
925 * renegotiate DLCI priorities with optional stuff. Needs optimising.
928 static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
931 /* Priority ordering: We should do priority with RR of the groups */
934 while (i < NUM_DLCI) {
935 struct gsm_dlci *dlci;
937 if (gsm->tx_bytes > TX_THRESH_HI)
940 if (dlci == NULL || dlci->constipated) {
944 if (dlci->adaption < 3 && !dlci->net)
945 len = gsm_dlci_data_output(gsm, dlci);
947 len = gsm_dlci_data_output_framed(gsm, dlci);
950 /* DLCI empty - try the next */
957 * gsm_dlci_data_kick - transmit if possible
958 * @dlci: DLCI to kick
960 * Transmit data from this DLCI if the queue is empty. We can't rely on
961 * a tty wakeup except when we filled the pipe so we need to fire off
962 * new data ourselves in other cases.
965 static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
970 if (dlci->constipated)
973 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
974 /* If we have nothing running then we need to fire up */
975 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
976 if (dlci->gsm->tx_bytes == 0) {
978 gsm_dlci_data_output_framed(dlci->gsm, dlci);
980 gsm_dlci_data_output(dlci->gsm, dlci);
983 gsm_dlci_data_sweep(dlci->gsm);
984 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
988 * Control message processing
993 * gsm_control_reply - send a response frame to a control
995 * @cmd: the command to use
996 * @data: data to follow encoded info
997 * @dlen: length of data
999 * Encode up and queue a UI/UIH frame containing our response.
1002 static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
1005 struct gsm_msg *msg;
1006 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
1009 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
1010 msg->data[1] = (dlen << 1) | EA;
1011 memcpy(msg->data + 2, data, dlen);
1012 gsm_data_queue(gsm->dlci[0], msg);
1016 * gsm_process_modem - process received modem status
1017 * @tty: virtual tty bound to the DLCI
1018 * @dlci: DLCI to affect
1019 * @modem: modem bits (full EA)
1020 * @clen: command length
1022 * Used when a modem control message or line state inline in adaption
1023 * layer 2 is processed. Sort out the local modem state and throttles
1026 static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1027 u32 modem, int clen)
1033 /* The modem status command can either contain one octet (v.24 signals)
1034 or two octets (v.24 signals + break signals). The length field will
1035 either be 2 or 3 respectively. This is specified in section
1036 5.4.6.3.7 of the 27.010 mux spec. */
1039 modem = modem & 0x7f;
1042 modem = (modem >> 7) & 0x7f;
1045 /* Flow control/ready to communicate */
1046 fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1047 if (fc && !dlci->constipated) {
1048 /* Need to throttle our output on this device */
1049 dlci->constipated = true;
1050 } else if (!fc && dlci->constipated) {
1051 dlci->constipated = false;
1052 gsm_dlci_data_kick(dlci);
1055 /* Map modem bits */
1056 if (modem & MDM_RTC)
1057 mlines |= TIOCM_DSR | TIOCM_DTR;
1058 if (modem & MDM_RTR)
1059 mlines |= TIOCM_RTS | TIOCM_CTS;
1065 /* Carrier drop -> hangup */
1067 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1072 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1073 dlci->modem_rx = mlines;
1077 * gsm_control_modem - modem status received
1079 * @data: data following command
1080 * @clen: command length
1082 * We have received a modem status control message. This is used by
1083 * the GSM mux protocol to pass virtual modem line status and optionally
1084 * to indicate break signals. Unpack it, convert to Linux representation
1085 * and if need be stuff a break message down the tty.
1088 static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1090 unsigned int addr = 0;
1091 unsigned int modem = 0;
1092 unsigned int brk = 0;
1093 struct gsm_dlci *dlci;
1095 const u8 *dp = data;
1096 struct tty_struct *tty;
1098 while (gsm_read_ea(&addr, *dp++) == 0) {
1103 /* Must be at least one byte following the EA */
1109 /* Closed port, or invalid ? */
1110 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1112 dlci = gsm->dlci[addr];
1114 while (gsm_read_ea(&modem, *dp++) == 0) {
1121 while (gsm_read_ea(&brk, *dp++) == 0) {
1127 modem |= (brk & 0x7f);
1129 tty = tty_port_tty_get(&dlci->port);
1130 gsm_process_modem(tty, dlci, modem, clen);
1135 gsm_control_reply(gsm, CMD_MSC, data, clen);
1139 * gsm_control_rls - remote line status
1142 * @clen: data length
1144 * The modem sends us a two byte message on the control channel whenever
1145 * it wishes to send us an error state from the virtual link. Stuff
1146 * this into the uplink tty if present
1149 static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1151 struct tty_port *port;
1152 unsigned int addr = 0;
1155 const u8 *dp = data;
1157 while (gsm_read_ea(&addr, *dp++) == 0) {
1162 /* Must be at least one byte following ea */
1167 /* Closed port, or invalid ? */
1168 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1172 if ((bits & 1) == 0)
1175 port = &gsm->dlci[addr]->port;
1178 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1180 tty_insert_flip_char(port, 0, TTY_PARITY);
1182 tty_insert_flip_char(port, 0, TTY_FRAME);
1184 tty_flip_buffer_push(port);
1186 gsm_control_reply(gsm, CMD_RLS, data, clen);
1189 static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1190 static void gsm_dlci_close(struct gsm_dlci *dlci);
1193 * gsm_control_message - DLCI 0 control processing
1195 * @command: the command EA
1196 * @data: data beyond the command/length EAs
1199 * Input processor for control messages from the other end of the link.
1200 * Processes the incoming request and queues a response frame or an
1201 * NSC response if not supported
1204 static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1205 const u8 *data, int clen)
1208 unsigned long flags;
1209 struct gsm_dlci *dlci;
1216 for (i = 0; i < addr_cnt; i++) {
1217 address = addr_open[i];
1218 dlci = gsm->dlci[address];
1219 gsm_dlci_close(dlci);
1223 /* Modem wishes to close down */
1224 dlci = gsm->dlci[0];
1228 gsm_dlci_close(dlci);
1230 gsm_response(gsm, 0, UA|PF);
1235 /* Modem wishes to test, reply with the data */
1236 gsm_control_reply(gsm, CMD_TEST, data, clen);
1239 /* Modem can accept data again */
1240 gsm->constipated = false;
1241 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1242 /* Kick the link in case it is idling */
1243 spin_lock_irqsave(&gsm->tx_lock, flags);
1244 gsm_data_kick(gsm, NULL);
1245 spin_unlock_irqrestore(&gsm->tx_lock, flags);
1248 /* Modem wants us to STFU */
1249 gsm->constipated = true;
1250 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1253 /* Out of band modem line change indicator for a DLCI */
1254 gsm_control_modem(gsm, data, clen);
1257 /* Out of band error reception for a DLCI */
1258 gsm_control_rls(gsm, data, clen);
1261 /* Modem wishes to enter power saving state */
1262 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1264 /* Optional unsupported commands */
1265 case CMD_PN: /* Parameter negotiation */
1266 case CMD_RPN: /* Remote port negotiation */
1267 case CMD_SNC: /* Service negotiation command */
1269 /* Reply to bad commands with an NSC */
1271 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1277 * gsm_control_response - process a response to our control
1279 * @command: the command (response) EA
1280 * @data: data beyond the command/length EA
1283 * Process a response to an outstanding command. We only allow a single
1284 * control message in flight so this is fairly easy. All the clean up
1285 * is done by the caller, we just update the fields, flag it as done
1289 static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1290 const u8 *data, int clen)
1292 struct gsm_control *ctrl;
1293 unsigned long flags;
1295 spin_lock_irqsave(&gsm->control_lock, flags);
1297 ctrl = gsm->pending_cmd;
1298 /* Does the reply match our command */
1300 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1301 /* Our command was replied to, kill the retry timer */
1302 del_timer(&gsm->t2_timer);
1303 gsm->pending_cmd = NULL;
1304 /* Rejected by the other end */
1305 if (command == CMD_NSC)
1306 ctrl->error = -EOPNOTSUPP;
1308 wake_up(&gsm->event);
1310 spin_unlock_irqrestore(&gsm->control_lock, flags);
1314 * gsm_control_transmit - send control packet
1316 * @ctrl: frame to send
1318 * Send out a pending control command (called under control lock)
1321 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1323 struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
1326 msg->data[0] = (ctrl->cmd << 1) | 2 | EA; /* command */
1327 memcpy(msg->data + 1, ctrl->data, ctrl->len);
1328 gsm_data_queue(gsm->dlci[0], msg);
1332 * gsm_control_retransmit - retransmit a control frame
1333 * @t: timer contained in our gsm object
1335 * Called off the T2 timer expiry in order to retransmit control frames
1336 * that have been lost in the system somewhere. The control_lock protects
1337 * us from colliding with another sender or a receive completion event.
1338 * In that situation the timer may still occur in a small window but
1339 * gsm->pending_cmd will be NULL and we just let the timer expire.
1342 static void gsm_control_retransmit(struct timer_list *t)
1344 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
1345 struct gsm_control *ctrl;
1346 unsigned long flags;
1347 spin_lock_irqsave(&gsm->control_lock, flags);
1348 ctrl = gsm->pending_cmd;
1351 if (gsm->cretries == 0) {
1352 gsm->pending_cmd = NULL;
1353 ctrl->error = -ETIMEDOUT;
1355 spin_unlock_irqrestore(&gsm->control_lock, flags);
1356 wake_up(&gsm->event);
1359 gsm_control_transmit(gsm, ctrl);
1360 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1362 spin_unlock_irqrestore(&gsm->control_lock, flags);
1366 * gsm_control_send - send a control frame on DLCI 0
1367 * @gsm: the GSM channel
1368 * @command: command to send including CR bit
1369 * @data: bytes of data (must be kmalloced)
1370 * @clen: length of the block to send
1372 * Queue and dispatch a control command. Only one command can be
1373 * active at a time. In theory more can be outstanding but the matching
1374 * gets really complicated so for now stick to one outstanding.
1377 static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1378 unsigned int command, u8 *data, int clen)
1380 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1382 unsigned long flags;
1386 wait_event(gsm->event, gsm->pending_cmd == NULL);
1387 spin_lock_irqsave(&gsm->control_lock, flags);
1388 if (gsm->pending_cmd != NULL) {
1389 spin_unlock_irqrestore(&gsm->control_lock, flags);
1392 ctrl->cmd = command;
1395 gsm->pending_cmd = ctrl;
1397 /* If DLCI0 is in ADM mode skip retries, it won't respond */
1398 if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
1401 gsm->cretries = gsm->n2;
1403 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1404 gsm_control_transmit(gsm, ctrl);
1405 spin_unlock_irqrestore(&gsm->control_lock, flags);
1410 * gsm_control_wait - wait for a control to finish
1412 * @control: control we are waiting on
1414 * Waits for the control to complete or time out. Frees any used
1415 * resources and returns 0 for success, or an error if the remote
1416 * rejected or ignored the request.
1419 static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
1422 wait_event(gsm->event, control->done == 1);
1423 err = control->error;
1430 * DLCI level handling: Needs krefs
1434 * State transitions and timers
1438 * gsm_dlci_close - a DLCI has closed
1439 * @dlci: DLCI that closed
1441 * Perform processing when moving a DLCI into closed state. If there
1442 * is an attached tty this is hung up
1445 static void gsm_dlci_close(struct gsm_dlci *dlci)
1447 del_timer(&dlci->t1);
1449 pr_debug("DLCI %d goes closed.\n", dlci->addr);
1450 dlci->state = DLCI_CLOSED;
1451 if (dlci->addr != 0) {
1452 tty_port_tty_hangup(&dlci->port, false);
1453 kfifo_reset(&dlci->fifo);
1455 dlci->gsm->dead = true;
1456 /* Unregister gsmtty driver,report gsmtty dev remove uevent for user */
1457 tty_unregister_device(gsm_tty_driver, dlci->addr);
1458 wake_up(&dlci->gsm->event);
1459 /* A DLCI 0 close is a MUX termination so we need to kick that
1460 back to userspace somehow */
1464 * gsm_dlci_open - a DLCI has opened
1465 * @dlci: DLCI that opened
1467 * Perform processing when moving a DLCI into open state.
1470 static void gsm_dlci_open(struct gsm_dlci *dlci)
1472 /* Note that SABM UA .. SABM UA first UA lost can mean that we go
1474 del_timer(&dlci->t1);
1475 /* This will let a tty open continue */
1476 dlci->state = DLCI_OPEN;
1478 pr_debug("DLCI %d goes open.\n", dlci->addr);
1479 /* Register gsmtty driver,report gsmtty dev add uevent for user */
1480 tty_register_device(gsm_tty_driver, dlci->addr, NULL);
1481 wake_up(&dlci->gsm->event);
1485 * gsm_dlci_t1 - T1 timer expiry
1486 * @t: timer contained in the DLCI that opened
1488 * The T1 timer handles retransmits of control frames (essentially of
1489 * SABM and DISC). We resend the command until the retry count runs out
1490 * in which case an opening port goes back to closed and a closing port
1491 * is simply put into closed state (any further frames from the other
1492 * end will get a DM response)
1494 * Some control dlci can stay in ADM mode with other dlci working just
1495 * fine. In that case we can just keep the control dlci open after the
1496 * DLCI_OPENING retries time out.
1499 static void gsm_dlci_t1(struct timer_list *t)
1501 struct gsm_dlci *dlci = from_timer(dlci, t, t1);
1502 struct gsm_mux *gsm = dlci->gsm;
1504 switch (dlci->state) {
1507 if (dlci->retries) {
1508 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1509 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1510 } else if (!dlci->addr && gsm->control == (DM | PF)) {
1512 pr_info("DLCI %d opening in ADM mode.\n",
1514 dlci->mode = DLCI_MODE_ADM;
1515 gsm_dlci_open(dlci);
1517 gsm_dlci_close(dlci);
1523 if (dlci->retries) {
1524 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1525 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1527 gsm_dlci_close(dlci);
1530 pr_debug("%s: unhandled state: %d\n", __func__, dlci->state);
1536 * gsm_dlci_begin_open - start channel open procedure
1537 * @dlci: DLCI to open
1539 * Commence opening a DLCI from the Linux side. We issue SABM messages
1540 * to the modem which should then reply with a UA or ADM, at which point
1541 * we will move into open state. Opening is done asynchronously with retry
1542 * running off timers and the responses.
1545 static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
1547 struct gsm_mux *gsm = dlci->gsm;
1548 if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING)
1550 dlci->retries = gsm->n2;
1551 dlci->state = DLCI_OPENING;
1552 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1553 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1557 * gsm_dlci_begin_close - start channel open procedure
1558 * @dlci: DLCI to open
1560 * Commence closing a DLCI from the Linux side. We issue DISC messages
1561 * to the modem which should then reply with a UA, at which point we
1562 * will move into closed state. Closing is done asynchronously with retry
1563 * off timers. We may also receive a DM reply from the other end which
1564 * indicates the channel was already closed.
1567 static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
1569 struct gsm_mux *gsm = dlci->gsm;
1570 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
1572 dlci->retries = gsm->n2;
1573 dlci->state = DLCI_CLOSING;
1574 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1575 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1579 * gsm_dlci_data - data arrived
1581 * @data: block of bytes received
1582 * @clen: length of received block
1584 * A UI or UIH frame has arrived which contains data for a channel
1585 * other than the control channel. If the relevant virtual tty is
1586 * open we shovel the bits down it, if not we drop them.
1589 static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
1592 struct tty_port *port = &dlci->port;
1593 struct tty_struct *tty;
1594 unsigned int modem = 0;
1598 pr_debug("%d bytes for tty\n", len);
1599 switch (dlci->adaption) {
1600 /* Unsupported types */
1601 case 4: /* Packetised interruptible data */
1603 case 3: /* Packetised uininterruptible voice/data */
1605 case 2: /* Asynchronous serial with line state in each frame */
1606 while (gsm_read_ea(&modem, *data++) == 0) {
1611 tty = tty_port_tty_get(port);
1613 gsm_process_modem(tty, dlci, modem, clen);
1617 case 1: /* Line state will go via DLCI 0 controls only */
1619 tty_insert_flip_string(port, data, len);
1620 tty_flip_buffer_push(port);
1625 * gsm_dlci_command - data arrived on control channel
1627 * @data: block of bytes received
1628 * @len: length of received block
1630 * A UI or UIH frame has arrived which contains data for DLCI 0 the
1631 * control channel. This should contain a command EA followed by
1632 * control data bytes. The command EA contains a command/response bit
1633 * and we divide up the work accordingly.
1636 static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
1638 /* See what command is involved */
1639 unsigned int command = 0;
1641 if (gsm_read_ea(&command, *data++) == 1) {
1644 /* FIXME: this is properly an EA */
1646 /* Malformed command ? */
1650 gsm_control_message(dlci->gsm, command,
1653 gsm_control_response(dlci->gsm, command,
1661 * Allocate/Free DLCI channels
1665 * gsm_dlci_alloc - allocate a DLCI
1667 * @addr: address of the DLCI
1669 * Allocate and install a new DLCI object into the GSM mux.
1671 * FIXME: review locking races
1674 static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
1676 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
1679 spin_lock_init(&dlci->lock);
1680 mutex_init(&dlci->mutex);
1681 if (kfifo_alloc(&dlci->fifo, 4096, GFP_KERNEL) < 0) {
1686 skb_queue_head_init(&dlci->skb_list);
1687 timer_setup(&dlci->t1, gsm_dlci_t1, 0);
1688 tty_port_init(&dlci->port);
1689 dlci->port.ops = &gsm_port_ops;
1692 dlci->adaption = gsm->adaption;
1693 dlci->state = DLCI_CLOSED;
1695 dlci->data = gsm_dlci_data;
1697 dlci->data = gsm_dlci_command;
1698 gsm->dlci[addr] = dlci;
1703 * gsm_dlci_free - free DLCI
1704 * @port: tty port for DLCI to free
1710 static void gsm_dlci_free(struct tty_port *port)
1712 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
1714 del_timer_sync(&dlci->t1);
1715 dlci->gsm->dlci[dlci->addr] = NULL;
1716 kfifo_free(&dlci->fifo);
1717 while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
1718 dev_kfree_skb(dlci->skb);
1722 static inline void dlci_get(struct gsm_dlci *dlci)
1724 tty_port_get(&dlci->port);
1727 static inline void dlci_put(struct gsm_dlci *dlci)
1729 tty_port_put(&dlci->port);
1732 static void gsm_destroy_network(struct gsm_dlci *dlci);
1735 * gsm_dlci_release - release DLCI
1736 * @dlci: DLCI to destroy
1738 * Release a DLCI. Actual free is deferred until either
1739 * mux is closed or tty is closed - whichever is last.
1743 static void gsm_dlci_release(struct gsm_dlci *dlci)
1745 struct tty_struct *tty = tty_port_tty_get(&dlci->port);
1747 mutex_lock(&dlci->mutex);
1748 gsm_destroy_network(dlci);
1749 mutex_unlock(&dlci->mutex);
1753 tty_port_tty_set(&dlci->port, NULL);
1756 dlci->state = DLCI_CLOSED;
1761 * LAPBish link layer logic
1765 * gsm_queue - a GSM frame is ready to process
1766 * @gsm: pointer to our gsm mux
1768 * At this point in time a frame has arrived and been demangled from
1769 * the line encoding. All the differences between the encodings have
1770 * been handled below us and the frame is unpacked into the structures.
1771 * The fcs holds the header FCS but any data FCS must be added here.
1774 static void gsm_queue(struct gsm_mux *gsm)
1776 struct gsm_dlci *dlci;
1779 int i, j, k, address_tmp;
1780 /* We have to sneak a look at the packet body to do the FCS.
1781 A somewhat layering violation in the spec */
1783 if ((gsm->control & ~PF) == UI)
1784 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
1785 if (gsm->encoding == 0) {
1786 /* WARNING: gsm->received_fcs is used for
1787 gsm->encoding = 0 only.
1788 In this case it contain the last piece of data
1789 required to generate final CRC */
1790 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
1792 if (gsm->fcs != GOOD_FCS) {
1795 pr_debug("BAD FCS %02x\n", gsm->fcs);
1798 address = gsm->address >> 1;
1799 if (address >= NUM_DLCI)
1802 cr = gsm->address & 1; /* C/R bit */
1804 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1806 cr ^= 1 - gsm->initiator; /* Flip so 1 always means command */
1807 dlci = gsm->dlci[address];
1809 switch (gsm->control) {
1814 dlci = gsm_dlci_alloc(gsm, address);
1818 gsm_response(gsm, address, DM|PF);
1820 gsm_response(gsm, address, UA|PF);
1821 gsm_dlci_open(dlci);
1822 /* Save dlci open address */
1824 addr_open[addr_cnt] = address;
1832 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1833 gsm_response(gsm, address, DM|PF);
1836 /* Real close complete */
1839 for (i = 0; i < addr_cnt; i++) {
1840 address = addr_open[i];
1841 dlci = gsm->dlci[address];
1842 gsm_dlci_close(dlci);
1846 dlci = gsm->dlci[0];
1847 gsm_dlci_close(dlci);
1849 gsm_response(gsm, 0, UA|PF);
1851 gsm_response(gsm, address, UA|PF);
1852 gsm_dlci_close(dlci);
1853 /* clear dlci address */
1854 for (j = 0; j < addr_cnt; j++) {
1855 address_tmp = addr_open[j];
1856 if (address_tmp == address) {
1857 for (k = j; k < addr_cnt; k++)
1858 addr_open[k] = addr_open[k+1];
1867 if (cr == 0 || dlci == NULL)
1869 switch (dlci->state) {
1871 gsm_dlci_close(dlci);
1874 gsm_dlci_open(dlci);
1877 pr_debug("%s: unhandled state: %d\n", __func__,
1882 case DM: /* DM can be valid unsolicited */
1888 gsm_dlci_close(dlci);
1898 if (dlci == NULL || dlci->state != DLCI_OPEN) {
1899 gsm_command(gsm, address, DM|PF);
1902 dlci->data(dlci, gsm->buf, gsm->len);
1915 * gsm0_receive - perform processing for non-transparency
1916 * @gsm: gsm data for this ldisc instance
1919 * Receive bytes in gsm mode 0
1922 static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
1926 switch (gsm->state) {
1927 case GSM_SEARCH: /* SOF marker */
1928 if (c == GSM0_SOF) {
1929 gsm->state = GSM_ADDRESS;
1932 gsm->fcs = INIT_FCS;
1935 case GSM_ADDRESS: /* Address EA */
1936 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1937 if (gsm_read_ea(&gsm->address, c))
1938 gsm->state = GSM_CONTROL;
1940 case GSM_CONTROL: /* Control Byte */
1941 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1943 gsm->state = GSM_LEN0;
1945 case GSM_LEN0: /* Length EA */
1946 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1947 if (gsm_read_ea(&gsm->len, c)) {
1948 if (gsm->len > gsm->mru) {
1950 gsm->state = GSM_SEARCH;
1955 gsm->state = GSM_FCS;
1957 gsm->state = GSM_DATA;
1960 gsm->state = GSM_LEN1;
1963 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1965 gsm->len |= len << 7;
1966 if (gsm->len > gsm->mru) {
1968 gsm->state = GSM_SEARCH;
1973 gsm->state = GSM_FCS;
1975 gsm->state = GSM_DATA;
1977 case GSM_DATA: /* Data */
1978 gsm->buf[gsm->count++] = c;
1979 if (gsm->count == gsm->len)
1980 gsm->state = GSM_FCS;
1982 case GSM_FCS: /* FCS follows the packet */
1983 gsm->received_fcs = c;
1985 gsm->state = GSM_SSOF;
1988 if (c == GSM0_SOF) {
1989 gsm->state = GSM_SEARCH;
1994 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2000 * gsm1_receive - perform processing for non-transparency
2001 * @gsm: gsm data for this ldisc instance
2004 * Receive bytes in mode 1 (Advanced option)
2007 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
2009 if (c == GSM1_SOF) {
2010 /* EOF is only valid in frame if we have got to the data state
2011 and received at least one byte (the FCS) */
2012 if (gsm->state == GSM_DATA && gsm->count) {
2013 /* Extract the FCS */
2015 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
2016 gsm->len = gsm->count;
2018 gsm->state = GSM_START;
2021 /* Any partial frame was a runt so go back to start */
2022 if (gsm->state != GSM_START) {
2024 gsm->state = GSM_START;
2026 /* A SOF in GSM_START means we are still reading idling or
2031 if (c == GSM1_ESCAPE) {
2036 /* Only an unescaped SOF gets us out of GSM search */
2037 if (gsm->state == GSM_SEARCH)
2041 c ^= GSM1_ESCAPE_BITS;
2042 gsm->escape = false;
2044 switch (gsm->state) {
2045 case GSM_START: /* First byte after SOF */
2047 gsm->state = GSM_ADDRESS;
2048 gsm->fcs = INIT_FCS;
2050 case GSM_ADDRESS: /* Address continuation */
2051 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2052 if (gsm_read_ea(&gsm->address, c))
2053 gsm->state = GSM_CONTROL;
2055 case GSM_CONTROL: /* Control Byte */
2056 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2059 gsm->state = GSM_DATA;
2061 case GSM_DATA: /* Data */
2062 if (gsm->count > gsm->mru) { /* Allow one for the FCS */
2063 gsm->state = GSM_OVERRUN;
2066 gsm->buf[gsm->count++] = c;
2068 case GSM_OVERRUN: /* Over-long - eg a dropped SOF */
2071 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2077 * gsm_error - handle tty error
2080 * Handle an error in the receipt of data for a frame. Currently we just
2081 * go back to hunting for a SOF.
2083 * FIXME: better diagnostics ?
2086 static void gsm_error(struct gsm_mux *gsm)
2088 gsm->state = GSM_SEARCH;
2092 static int gsm_disconnect(struct gsm_mux *gsm)
2094 struct gsm_dlci *dlci = gsm->dlci[0];
2095 struct gsm_control *gc;
2100 /* In theory disconnecting DLCI 0 is sufficient but for some
2101 modems this is apparently not the case. */
2102 gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
2104 gsm_control_wait(gsm, gc);
2106 del_timer_sync(&gsm->t2_timer);
2107 /* Now we are sure T2 has stopped */
2109 gsm_dlci_begin_close(dlci);
2110 wait_event_interruptible(gsm->event,
2111 dlci->state == DLCI_CLOSED);
2113 if (signal_pending(current))
2120 * gsm_cleanup_mux - generic GSM protocol cleanup
2123 * Clean up the bits of the mux which are the same for all framing
2124 * protocols. Remove the mux from the mux table, stop all the timers
2125 * and then shut down each device hanging up the channels as we go.
2128 static void gsm_cleanup_mux(struct gsm_mux *gsm)
2131 struct gsm_dlci *dlci = gsm->dlci[0];
2132 struct gsm_msg *txq, *ntxq;
2136 spin_lock(&gsm_mux_lock);
2137 for (i = 0; i < MAX_MUX; i++) {
2138 if (gsm_mux[i] == gsm) {
2143 spin_unlock(&gsm_mux_lock);
2144 /* open failed before registering => nothing to do */
2148 del_timer_sync(&gsm->t2_timer);
2149 /* Now we are sure T2 has stopped */
2153 /* Free up any link layer users */
2154 mutex_lock(&gsm->mutex);
2155 for (i = 0; i < NUM_DLCI; i++)
2157 gsm_dlci_release(gsm->dlci[i]);
2158 mutex_unlock(&gsm->mutex);
2159 /* Now wipe the queues */
2160 list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2162 INIT_LIST_HEAD(&gsm->tx_list);
2166 * gsm_activate_mux - generic GSM setup
2169 * Set up the bits of the mux which are the same for all framing
2170 * protocols. Add the mux to the mux table so it can be opened and
2171 * finally kick off connecting to DLCI 0 on the modem.
2174 static int gsm_activate_mux(struct gsm_mux *gsm)
2176 struct gsm_dlci *dlci;
2179 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
2180 init_waitqueue_head(&gsm->event);
2181 spin_lock_init(&gsm->control_lock);
2182 spin_lock_init(&gsm->tx_lock);
2184 if (gsm->encoding == 0)
2185 gsm->receive = gsm0_receive;
2187 gsm->receive = gsm1_receive;
2189 spin_lock(&gsm_mux_lock);
2190 for (i = 0; i < MAX_MUX; i++) {
2191 if (gsm_mux[i] == NULL) {
2197 spin_unlock(&gsm_mux_lock);
2201 dlci = gsm_dlci_alloc(gsm, 0);
2204 gsm->dead = false; /* Tty opens are now permissible */
2209 * gsm_free_mux - free up a mux
2212 * Dispose of allocated resources for a dead mux
2214 static void gsm_free_mux(struct gsm_mux *gsm)
2216 kfree(gsm->txframe);
2222 * gsm_free_muxr - free up a mux
2223 * @ref: kreference to the mux to free
2225 * Dispose of allocated resources for a dead mux
2227 static void gsm_free_muxr(struct kref *ref)
2229 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2233 static inline void mux_get(struct gsm_mux *gsm)
2235 kref_get(&gsm->ref);
2238 static inline void mux_put(struct gsm_mux *gsm)
2240 kref_put(&gsm->ref, gsm_free_muxr);
2243 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
2245 return gsm->num * NUM_DLCI;
2248 static inline unsigned int mux_line_to_num(unsigned int line)
2250 return line / NUM_DLCI;
2254 * gsm_alloc_mux - allocate a mux
2256 * Creates a new mux ready for activation.
2259 static struct gsm_mux *gsm_alloc_mux(void)
2261 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2264 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2265 if (gsm->buf == NULL) {
2269 gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
2270 if (gsm->txframe == NULL) {
2275 spin_lock_init(&gsm->lock);
2276 mutex_init(&gsm->mutex);
2277 kref_init(&gsm->ref);
2278 INIT_LIST_HEAD(&gsm->tx_list);
2286 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
2288 gsm->dead = true; /* Avoid early tty opens */
2293 static void gsm_copy_config_values(struct gsm_mux *gsm,
2294 struct gsm_config *c)
2296 memset(c, 0, sizeof(*c));
2297 c->adaption = gsm->adaption;
2298 c->encapsulation = gsm->encoding;
2299 c->initiator = gsm->initiator;
2302 c->t3 = 0; /* Not supported */
2304 if (gsm->ftype == UIH)
2308 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
2314 static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
2317 int need_restart = 0;
2319 /* Stuff we don't support yet - UI or I frame transport, windowing */
2320 if ((c->adaption != 1 && c->adaption != 2) || c->k)
2322 /* Check the MRU/MTU range looks sane */
2323 if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2327 if (c->encapsulation > 1) /* Basic, advanced, no I */
2329 if (c->initiator > 1)
2331 if (c->i == 0 || c->i > 2) /* UIH and UI only */
2334 * See what is needed for reconfiguration
2338 if (c->t1 != 0 && c->t1 != gsm->t1)
2340 if (c->t2 != 0 && c->t2 != gsm->t2)
2342 if (c->encapsulation != gsm->encoding)
2344 if (c->adaption != gsm->adaption)
2347 if (c->initiator != gsm->initiator)
2349 if (c->mru != gsm->mru)
2351 if (c->mtu != gsm->mtu)
2355 * Close down what is needed, restart and initiate the new
2359 if (gsm->initiator && (need_close || need_restart)) {
2362 ret = gsm_disconnect(gsm);
2368 gsm_cleanup_mux(gsm);
2370 gsm->initiator = c->initiator;
2373 gsm->encoding = c->encapsulation;
2374 gsm->adaption = c->adaption;
2388 * FIXME: We need to separate activation/deactivation from adding
2389 * and removing from the mux array
2392 gsm_activate_mux(gsm);
2393 if (gsm->initiator && need_close)
2394 gsm_dlci_begin_open(gsm->dlci[0]);
2399 * gsmld_output - write to link
2401 * @data: bytes to output
2404 * Write a block of data from the GSM mux to the data channel. This
2405 * will eventually be serialized from above but at the moment isn't.
2408 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2410 if (tty_write_room(gsm->tty) < len) {
2411 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2415 print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET,
2417 return gsm->tty->ops->write(gsm->tty, data, len);
2421 * gsmld_attach_gsm - mode set up
2422 * @tty: our tty structure
2425 * Set up the MUX for basic mode and commence connecting to the
2426 * modem. Currently called from the line discipline set up but
2427 * will need moving to an ioctl path.
2430 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2435 gsm->tty = tty_kref_get(tty);
2436 ret = gsm_activate_mux(gsm);
2438 tty_kref_put(gsm->tty);
2440 /* Don't register device 0 - this is the control channel and not
2441 a usable tty interface */
2442 if (gsm->initiator) {
2443 base = mux_num_to_base(gsm); /* Base for this MUX */
2444 for (i = 1; i < NUM_DLCI; i++) {
2447 dev = tty_register_device(gsm_tty_driver,
2450 for (i--; i >= 1; i--)
2451 tty_unregister_device(gsm_tty_driver,
2453 return PTR_ERR(dev);
2463 * gsmld_detach_gsm - stop doing 0710 mux
2464 * @tty: tty attached to the mux
2467 * Shutdown and then clean up the resources used by the line discipline
2470 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2472 unsigned int base = mux_num_to_base(gsm); /* Base for this MUX */
2475 WARN_ON(tty != gsm->tty);
2476 if (gsm->initiator) {
2477 for (i = 1; i < NUM_DLCI; i++)
2478 tty_unregister_device(gsm_tty_driver, base + i);
2480 gsm_cleanup_mux(gsm);
2481 tty_kref_put(gsm->tty);
2485 static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2486 const char *fp, int count)
2488 struct gsm_mux *gsm = tty->disc_data;
2489 char flags = TTY_NORMAL;
2492 print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
2495 for (; count; count--, cp++) {
2500 gsm->receive(gsm, *cp);
2509 WARN_ONCE(1, "%s: unknown flag %d\n",
2510 tty_name(tty), flags);
2514 /* FASYNC if needed ? */
2515 /* If clogged call tty_throttle(tty); */
2519 * gsmld_flush_buffer - clean input queue
2520 * @tty: terminal device
2522 * Flush the input buffer. Called when the line discipline is
2523 * being closed, when the tty layer wants the buffer flushed (eg
2527 static void gsmld_flush_buffer(struct tty_struct *tty)
2532 * gsmld_close - close the ldisc for this tty
2535 * Called from the terminal layer when this line discipline is
2536 * being shut down, either because of a close or becsuse of a
2537 * discipline change. The function will not be called while other
2538 * ldisc methods are in progress.
2541 static void gsmld_close(struct tty_struct *tty)
2543 struct gsm_mux *gsm = tty->disc_data;
2545 gsmld_detach_gsm(tty, gsm);
2547 gsmld_flush_buffer(tty);
2548 /* Do other clean up here */
2553 * gsmld_open - open an ldisc
2554 * @tty: terminal to open
2556 * Called when this line discipline is being attached to the
2557 * terminal device. Can sleep. Called serialized so that no
2558 * other events will occur in parallel. No further open will occur
2562 static int gsmld_open(struct tty_struct *tty)
2564 struct gsm_mux *gsm;
2567 if (tty->ops->write == NULL)
2570 /* Attach our ldisc data */
2571 gsm = gsm_alloc_mux();
2575 tty->disc_data = gsm;
2576 tty->receive_room = 65536;
2578 /* Attach the initial passive connection */
2581 ret = gsmld_attach_gsm(tty, gsm);
2583 gsm_cleanup_mux(gsm);
2590 * gsmld_write_wakeup - asynchronous I/O notifier
2593 * Required for the ptys, serial driver etc. since processes
2594 * that attach themselves to the master and rely on ASYNC
2595 * IO must be woken up
2598 static void gsmld_write_wakeup(struct tty_struct *tty)
2600 struct gsm_mux *gsm = tty->disc_data;
2601 unsigned long flags;
2604 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2605 spin_lock_irqsave(&gsm->tx_lock, flags);
2606 gsm_data_kick(gsm, NULL);
2607 if (gsm->tx_bytes < TX_THRESH_LO) {
2608 gsm_dlci_data_sweep(gsm);
2610 spin_unlock_irqrestore(&gsm->tx_lock, flags);
2614 * gsmld_read - read function for tty
2616 * @file: file object
2617 * @buf: userspace buffer pointer
2622 * Perform reads for the line discipline. We are guaranteed that the
2623 * line discipline will not be closed under us but we may get multiple
2624 * parallel readers and must handle this ourselves. We may also get
2625 * a hangup. Always called in user context, may sleep.
2627 * This code must be sure never to sleep through a hangup.
2630 static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2631 unsigned char *buf, size_t nr,
2632 void **cookie, unsigned long offset)
2638 * gsmld_write - write function for tty
2640 * @file: file object
2641 * @buf: userspace buffer pointer
2644 * Called when the owner of the device wants to send a frame
2645 * itself (or some other control data). The data is transferred
2646 * as-is and must be properly framed and checksummed as appropriate
2647 * by userspace. Frames are either sent whole or not at all as this
2648 * avoids pain user side.
2651 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2652 const unsigned char *buf, size_t nr)
2654 int space = tty_write_room(tty);
2656 return tty->ops->write(tty, buf, nr);
2657 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2662 * gsmld_poll - poll method for N_GSM0710
2663 * @tty: terminal device
2664 * @file: file accessing it
2667 * Called when the line discipline is asked to poll() for data or
2668 * for special events. This code is not serialized with respect to
2669 * other events save open/close.
2671 * This code must be sure never to sleep through a hangup.
2672 * Called without the kernel lock held - fine
2675 static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
2679 struct gsm_mux *gsm = tty->disc_data;
2681 poll_wait(file, &tty->read_wait, wait);
2682 poll_wait(file, &tty->write_wait, wait);
2683 if (tty_hung_up_p(file))
2685 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2686 mask |= EPOLLOUT | EPOLLWRNORM;
2692 static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd,
2695 struct gsm_config c;
2696 struct gsm_mux *gsm = tty->disc_data;
2700 case GSMIOC_GETCONF:
2701 gsm_copy_config_values(gsm, &c);
2702 if (copy_to_user((void __user *)arg, &c, sizeof(c)))
2705 case GSMIOC_SETCONF:
2706 if (copy_from_user(&c, (void __user *)arg, sizeof(c)))
2708 return gsm_config(gsm, &c);
2709 case GSMIOC_GETFIRST:
2710 base = mux_num_to_base(gsm);
2711 return put_user(base + 1, (__u32 __user *)arg);
2713 return n_tty_ioctl_helper(tty, cmd, arg);
2722 static int gsm_mux_net_open(struct net_device *net)
2724 pr_debug("%s called\n", __func__);
2725 netif_start_queue(net);
2729 static int gsm_mux_net_close(struct net_device *net)
2731 netif_stop_queue(net);
2735 static void dlci_net_free(struct gsm_dlci *dlci)
2741 dlci->adaption = dlci->prev_adaption;
2742 dlci->data = dlci->prev_data;
2743 free_netdev(dlci->net);
2746 static void net_free(struct kref *ref)
2748 struct gsm_mux_net *mux_net;
2749 struct gsm_dlci *dlci;
2751 mux_net = container_of(ref, struct gsm_mux_net, ref);
2752 dlci = mux_net->dlci;
2755 unregister_netdev(dlci->net);
2756 dlci_net_free(dlci);
2760 static inline void muxnet_get(struct gsm_mux_net *mux_net)
2762 kref_get(&mux_net->ref);
2765 static inline void muxnet_put(struct gsm_mux_net *mux_net)
2767 kref_put(&mux_net->ref, net_free);
2770 static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
2771 struct net_device *net)
2773 struct gsm_mux_net *mux_net = netdev_priv(net);
2774 struct gsm_dlci *dlci = mux_net->dlci;
2775 muxnet_get(mux_net);
2777 skb_queue_head(&dlci->skb_list, skb);
2778 net->stats.tx_packets++;
2779 net->stats.tx_bytes += skb->len;
2780 gsm_dlci_data_kick(dlci);
2781 /* And tell the kernel when the last transmit started. */
2782 netif_trans_update(net);
2783 muxnet_put(mux_net);
2784 return NETDEV_TX_OK;
2787 /* called when a packet did not ack after watchdogtimeout */
2788 static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue)
2790 /* Tell syslog we are hosed. */
2791 dev_dbg(&net->dev, "Tx timed out.\n");
2793 /* Update statistics */
2794 net->stats.tx_errors++;
2797 static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2798 const unsigned char *in_buf, int size)
2800 struct net_device *net = dlci->net;
2801 struct sk_buff *skb;
2802 struct gsm_mux_net *mux_net = netdev_priv(net);
2803 muxnet_get(mux_net);
2805 /* Allocate an sk_buff */
2806 skb = dev_alloc_skb(size + NET_IP_ALIGN);
2808 /* We got no receive buffer. */
2809 net->stats.rx_dropped++;
2810 muxnet_put(mux_net);
2813 skb_reserve(skb, NET_IP_ALIGN);
2814 skb_put_data(skb, in_buf, size);
2817 skb->protocol = htons(ETH_P_IP);
2819 /* Ship it off to the kernel */
2822 /* update out statistics */
2823 net->stats.rx_packets++;
2824 net->stats.rx_bytes += size;
2825 muxnet_put(mux_net);
2829 static void gsm_mux_net_init(struct net_device *net)
2831 static const struct net_device_ops gsm_netdev_ops = {
2832 .ndo_open = gsm_mux_net_open,
2833 .ndo_stop = gsm_mux_net_close,
2834 .ndo_start_xmit = gsm_mux_net_start_xmit,
2835 .ndo_tx_timeout = gsm_mux_net_tx_timeout,
2838 net->netdev_ops = &gsm_netdev_ops;
2840 /* fill in the other fields */
2841 net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2842 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2843 net->type = ARPHRD_NONE;
2844 net->tx_queue_len = 10;
2848 /* caller holds the dlci mutex */
2849 static void gsm_destroy_network(struct gsm_dlci *dlci)
2851 struct gsm_mux_net *mux_net;
2853 pr_debug("destroy network interface\n");
2856 mux_net = netdev_priv(dlci->net);
2857 muxnet_put(mux_net);
2861 /* caller holds the dlci mutex */
2862 static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2866 struct net_device *net;
2867 struct gsm_mux_net *mux_net;
2869 if (!capable(CAP_NET_ADMIN))
2872 /* Already in a non tty mode */
2873 if (dlci->adaption > 2)
2876 if (nc->protocol != htons(ETH_P_IP))
2877 return -EPROTONOSUPPORT;
2879 if (nc->adaption != 3 && nc->adaption != 4)
2880 return -EPROTONOSUPPORT;
2882 pr_debug("create network interface\n");
2885 if (nc->if_name[0] != '\0')
2886 netname = nc->if_name;
2887 net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
2888 NET_NAME_UNKNOWN, gsm_mux_net_init);
2890 pr_err("alloc_netdev failed\n");
2893 net->mtu = dlci->gsm->mtu;
2895 net->max_mtu = dlci->gsm->mtu;
2896 mux_net = netdev_priv(net);
2897 mux_net->dlci = dlci;
2898 kref_init(&mux_net->ref);
2899 strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
2901 /* reconfigure dlci for network */
2902 dlci->prev_adaption = dlci->adaption;
2903 dlci->prev_data = dlci->data;
2904 dlci->adaption = nc->adaption;
2905 dlci->data = gsm_mux_rx_netchar;
2908 pr_debug("register netdev\n");
2909 retval = register_netdev(net);
2911 pr_err("network register fail %d\n", retval);
2912 dlci_net_free(dlci);
2915 return net->ifindex; /* return network index */
2918 /* Line discipline for real tty */
2919 static struct tty_ldisc_ops tty_ldisc_packet = {
2920 .owner = THIS_MODULE,
2924 .close = gsmld_close,
2925 .flush_buffer = gsmld_flush_buffer,
2927 .write = gsmld_write,
2928 .ioctl = gsmld_ioctl,
2930 .receive_buf = gsmld_receive_buf,
2931 .write_wakeup = gsmld_write_wakeup
2940 static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
2943 struct gsm_control *ctrl;
2949 modembits[0] = len << 1 | EA; /* Data bytes */
2950 modembits[1] = dlci->addr << 2 | 3; /* DLCI, EA, 1 */
2951 modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
2953 modembits[3] = brk << 4 | 2 | EA; /* Valid, EA */
2954 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
2957 return gsm_control_wait(dlci->gsm, ctrl);
2960 static int gsm_carrier_raised(struct tty_port *port)
2962 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2963 struct gsm_mux *gsm = dlci->gsm;
2965 /* Not yet open so no carrier info */
2966 if (dlci->state != DLCI_OPEN)
2972 * Basic mode with control channel in ADM mode may not respond
2973 * to CMD_MSC at all and modem_rx is empty.
2975 if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
2979 return dlci->modem_rx & TIOCM_CD;
2982 static void gsm_dtr_rts(struct tty_port *port, int onoff)
2984 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2985 unsigned int modem_tx = dlci->modem_tx;
2987 modem_tx |= TIOCM_DTR | TIOCM_RTS;
2989 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
2990 if (modem_tx != dlci->modem_tx) {
2991 dlci->modem_tx = modem_tx;
2992 gsmtty_modem_update(dlci, 0);
2996 static const struct tty_port_operations gsm_port_ops = {
2997 .carrier_raised = gsm_carrier_raised,
2998 .dtr_rts = gsm_dtr_rts,
2999 .destruct = gsm_dlci_free,
3002 static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
3004 struct gsm_mux *gsm;
3005 struct gsm_dlci *dlci;
3006 unsigned int line = tty->index;
3007 unsigned int mux = mux_line_to_num(line);
3015 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
3016 if (gsm_mux[mux] == NULL)
3018 if (line == 0 || line > 61) /* 62/63 reserved */
3023 /* If DLCI 0 is not yet fully open return an error.
3024 This is ok from a locking
3025 perspective as we don't have to worry about this
3027 mutex_lock(&gsm->mutex);
3028 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
3029 mutex_unlock(&gsm->mutex);
3032 dlci = gsm->dlci[line];
3035 dlci = gsm_dlci_alloc(gsm, line);
3038 mutex_unlock(&gsm->mutex);
3041 ret = tty_port_install(&dlci->port, driver, tty);
3045 mutex_unlock(&gsm->mutex);
3050 dlci_get(gsm->dlci[0]);
3052 tty->driver_data = dlci;
3053 mutex_unlock(&gsm->mutex);
3058 static int gsmtty_open(struct tty_struct *tty, struct file *filp)
3060 struct gsm_dlci *dlci = tty->driver_data;
3061 struct tty_port *port = &dlci->port;
3062 struct gsm_mux *gsm = dlci->gsm;
3065 tty_port_tty_set(port, tty);
3068 /* We could in theory open and close before we wait - eg if we get
3069 a DM straight back. This is ok as that will have caused a hangup */
3070 tty_port_set_initialized(port, 1);
3071 /* Start sending off SABM messages */
3073 gsm_dlci_begin_open(dlci);
3074 /* And wait for virtual carrier */
3075 return tty_port_block_til_ready(port, tty, filp);
3078 static void gsmtty_close(struct tty_struct *tty, struct file *filp)
3080 struct gsm_dlci *dlci = tty->driver_data;
3084 if (dlci->state == DLCI_CLOSED)
3086 mutex_lock(&dlci->mutex);
3087 gsm_destroy_network(dlci);
3088 mutex_unlock(&dlci->mutex);
3089 if (tty_port_close_start(&dlci->port, tty, filp) == 0)
3091 gsm_dlci_begin_close(dlci);
3092 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
3093 tty_port_lower_dtr_rts(&dlci->port);
3094 tty_port_close_end(&dlci->port, tty);
3095 tty_port_tty_set(&dlci->port, NULL);
3099 static void gsmtty_hangup(struct tty_struct *tty)
3101 struct gsm_dlci *dlci = tty->driver_data;
3102 if (dlci->state == DLCI_CLOSED)
3104 tty_port_hangup(&dlci->port);
3105 gsm_dlci_begin_close(dlci);
3108 static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
3112 struct gsm_dlci *dlci = tty->driver_data;
3113 if (dlci->state == DLCI_CLOSED)
3115 /* Stuff the bytes into the fifo queue */
3116 sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock);
3117 /* Need to kick the channel */
3118 gsm_dlci_data_kick(dlci);
3122 static unsigned int gsmtty_write_room(struct tty_struct *tty)
3124 struct gsm_dlci *dlci = tty->driver_data;
3125 if (dlci->state == DLCI_CLOSED)
3127 return TX_SIZE - kfifo_len(&dlci->fifo);
3130 static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty)
3132 struct gsm_dlci *dlci = tty->driver_data;
3133 if (dlci->state == DLCI_CLOSED)
3135 return kfifo_len(&dlci->fifo);
3138 static void gsmtty_flush_buffer(struct tty_struct *tty)
3140 struct gsm_dlci *dlci = tty->driver_data;
3141 if (dlci->state == DLCI_CLOSED)
3143 /* Caution needed: If we implement reliable transport classes
3144 then the data being transmitted can't simply be junked once
3145 it has first hit the stack. Until then we can just blow it
3147 kfifo_reset(&dlci->fifo);
3148 /* Need to unhook this DLCI from the transmit queue logic */
3151 static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3153 /* The FIFO handles the queue so the kernel will do the right
3154 thing waiting on chars_in_buffer before calling us. No work
3158 static int gsmtty_tiocmget(struct tty_struct *tty)
3160 struct gsm_dlci *dlci = tty->driver_data;
3161 if (dlci->state == DLCI_CLOSED)
3163 return dlci->modem_rx;
3166 static int gsmtty_tiocmset(struct tty_struct *tty,
3167 unsigned int set, unsigned int clear)
3169 struct gsm_dlci *dlci = tty->driver_data;
3170 unsigned int modem_tx = dlci->modem_tx;
3172 if (dlci->state == DLCI_CLOSED)
3177 if (modem_tx != dlci->modem_tx) {
3178 dlci->modem_tx = modem_tx;
3179 return gsmtty_modem_update(dlci, 0);
3185 static int gsmtty_ioctl(struct tty_struct *tty,
3186 unsigned int cmd, unsigned long arg)
3188 struct gsm_dlci *dlci = tty->driver_data;
3189 struct gsm_netconfig nc;
3192 if (dlci->state == DLCI_CLOSED)
3195 case GSMIOC_ENABLE_NET:
3196 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3198 nc.if_name[IFNAMSIZ-1] = '\0';
3199 /* return net interface index or error code */
3200 mutex_lock(&dlci->mutex);
3201 index = gsm_create_network(dlci, &nc);
3202 mutex_unlock(&dlci->mutex);
3203 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3206 case GSMIOC_DISABLE_NET:
3207 if (!capable(CAP_NET_ADMIN))
3209 mutex_lock(&dlci->mutex);
3210 gsm_destroy_network(dlci);
3211 mutex_unlock(&dlci->mutex);
3214 return -ENOIOCTLCMD;
3218 static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3220 struct gsm_dlci *dlci = tty->driver_data;
3221 if (dlci->state == DLCI_CLOSED)
3223 /* For the moment its fixed. In actual fact the speed information
3224 for the virtual channel can be propogated in both directions by
3225 the RPN control message. This however rapidly gets nasty as we
3226 then have to remap modem signals each way according to whether
3227 our virtual cable is null modem etc .. */
3228 tty_termios_copy_hw(&tty->termios, old);
3231 static void gsmtty_throttle(struct tty_struct *tty)
3233 struct gsm_dlci *dlci = tty->driver_data;
3234 if (dlci->state == DLCI_CLOSED)
3237 dlci->modem_tx &= ~TIOCM_DTR;
3238 dlci->throttled = true;
3239 /* Send an MSC with DTR cleared */
3240 gsmtty_modem_update(dlci, 0);
3243 static void gsmtty_unthrottle(struct tty_struct *tty)
3245 struct gsm_dlci *dlci = tty->driver_data;
3246 if (dlci->state == DLCI_CLOSED)
3249 dlci->modem_tx |= TIOCM_DTR;
3250 dlci->throttled = false;
3251 /* Send an MSC with DTR set */
3252 gsmtty_modem_update(dlci, 0);
3255 static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3257 struct gsm_dlci *dlci = tty->driver_data;
3258 int encode = 0; /* Off */
3259 if (dlci->state == DLCI_CLOSED)
3262 if (state == -1) /* "On indefinitely" - we can't encode this
3265 else if (state > 0) {
3266 encode = state / 200; /* mS to encoding */
3268 encode = 0x0F; /* Best effort */
3270 return gsmtty_modem_update(dlci, encode);
3273 static void gsmtty_cleanup(struct tty_struct *tty)
3275 struct gsm_dlci *dlci = tty->driver_data;
3276 struct gsm_mux *gsm = dlci->gsm;
3279 dlci_put(gsm->dlci[0]);
3283 /* Virtual ttys for the demux */
3284 static const struct tty_operations gsmtty_ops = {
3285 .install = gsmtty_install,
3286 .open = gsmtty_open,
3287 .close = gsmtty_close,
3288 .write = gsmtty_write,
3289 .write_room = gsmtty_write_room,
3290 .chars_in_buffer = gsmtty_chars_in_buffer,
3291 .flush_buffer = gsmtty_flush_buffer,
3292 .ioctl = gsmtty_ioctl,
3293 .throttle = gsmtty_throttle,
3294 .unthrottle = gsmtty_unthrottle,
3295 .set_termios = gsmtty_set_termios,
3296 .hangup = gsmtty_hangup,
3297 .wait_until_sent = gsmtty_wait_until_sent,
3298 .tiocmget = gsmtty_tiocmget,
3299 .tiocmset = gsmtty_tiocmset,
3300 .break_ctl = gsmtty_break_ctl,
3301 .cleanup = gsmtty_cleanup,
3306 static int __init gsm_init(void)
3308 /* Fill in our line protocol discipline, and register it */
3309 int status = tty_register_ldisc(&tty_ldisc_packet);
3311 pr_err("n_gsm: can't register line discipline (err = %d)\n",
3316 gsm_tty_driver = tty_alloc_driver(256, TTY_DRIVER_REAL_RAW |
3317 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_HARDWARE_BREAK);
3318 if (IS_ERR(gsm_tty_driver)) {
3319 pr_err("gsm_init: tty allocation failed.\n");
3320 status = PTR_ERR(gsm_tty_driver);
3321 goto err_unreg_ldisc;
3323 gsm_tty_driver->driver_name = "gsmtty";
3324 gsm_tty_driver->name = "gsmtty";
3325 gsm_tty_driver->major = 0; /* Dynamic */
3326 gsm_tty_driver->minor_start = 0;
3327 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
3328 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3329 gsm_tty_driver->init_termios = tty_std_termios;
3331 gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3332 tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3334 if (tty_register_driver(gsm_tty_driver)) {
3335 pr_err("gsm_init: tty registration failed.\n");
3337 goto err_put_driver;
3339 pr_debug("gsm_init: loaded as %d,%d.\n",
3340 gsm_tty_driver->major, gsm_tty_driver->minor_start);
3343 tty_driver_kref_put(gsm_tty_driver);
3345 tty_unregister_ldisc(&tty_ldisc_packet);
3349 static void __exit gsm_exit(void)
3351 tty_unregister_ldisc(&tty_ldisc_packet);
3352 tty_unregister_driver(gsm_tty_driver);
3353 tty_driver_kref_put(gsm_tty_driver);
3356 module_init(gsm_init);
3357 module_exit(gsm_exit);
3360 MODULE_LICENSE("GPL");
3361 MODULE_ALIAS_LDISC(N_GSM0710);