1 // SPDX-License-Identifier: GPL-2.0
3 * n_gsm.c GSM 0710 tty multiplexor
4 * Copyright (c) 2009/10 Intel Corporation
6 * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
9 * Mostly done: ioctls for setting modes/timing
10 * Partly done: hooks so you can pull off frames to non tty devs
11 * Restart DLCI 0 when it closes ?
12 * Improve the tx engine
13 * Resolve tx side locking by adding a queue_head and routing
14 * all control traffic via it
15 * General tidy/document
16 * Review the locking/move to refcounts more (mux now moved to an
17 * alloc/free model ready)
18 * Use newest tty open/close port helpers and install hooks
19 * What to do about power functions ?
20 * Termios setting and negotiation
21 * Do we need a 'which mux are you' ioctl to correlate mux and tty sets
25 #include <linux/types.h>
26 #include <linux/major.h>
27 #include <linux/errno.h>
28 #include <linux/signal.h>
29 #include <linux/fcntl.h>
30 #include <linux/sched/signal.h>
31 #include <linux/interrupt.h>
32 #include <linux/tty.h>
33 #include <linux/ctype.h>
35 #include <linux/string.h>
36 #include <linux/slab.h>
37 #include <linux/poll.h>
38 #include <linux/bitops.h>
39 #include <linux/file.h>
40 #include <linux/uaccess.h>
41 #include <linux/module.h>
42 #include <linux/timer.h>
43 #include <linux/tty_flip.h>
44 #include <linux/tty_driver.h>
45 #include <linux/serial.h>
46 #include <linux/kfifo.h>
47 #include <linux/skbuff.h>
50 #include <linux/netdevice.h>
51 #include <linux/etherdevice.h>
52 #include <linux/gsmmux.h>
55 module_param(debug, int, 0600);
57 /* Defaults: these are from the specification */
59 #define T1 10 /* 100mS */
60 #define T2 34 /* 333mS */
61 #define N2 3 /* Retry 3 times */
63 /* Use long timers for testing at low speed with debug on */
70 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
71 * limits so this is plenty
75 #define GSM_NET_TX_TIMEOUT (HZ*10)
78 * struct gsm_mux_net - network interface
79 * @struct gsm_dlci* dlci
81 * Created when net interface is initialized.
85 struct gsm_dlci *dlci;
89 * Each block of data we have queued to go out is in the form of
90 * a gsm_msg which holds everything we need in a link layer independent
95 struct list_head list;
96 u8 addr; /* DLCI address + flags */
97 u8 ctrl; /* Control byte + flags */
98 unsigned int len; /* Length of data block (can be zero) */
99 unsigned char *data; /* Points into buffer but not at the start */
100 unsigned char buffer[];
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 spinlock_t gsm_mux_lock;
272 static struct tty_driver *gsm_tty_driver;
275 * This section of the driver logic implements the GSM encodings
276 * both the basic and the 'advanced'. Reliable transport is not
284 /* I is special: the rest are ..*/
295 /* Channel commands */
297 #define CMD_TEST 0x11
300 #define CMD_FCOFF 0x31
303 #define CMD_FCON 0x51
308 /* Virtual modem bits */
315 #define GSM0_SOF 0xF9
316 #define GSM1_SOF 0x7E
317 #define GSM1_ESCAPE 0x7D
318 #define GSM1_ESCAPE_BITS 0x20
322 static const struct tty_port_operations gsm_port_ops;
325 * CRC table for GSM 0710
328 static const u8 gsm_fcs8[256] = {
329 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
330 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
331 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
332 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
333 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
334 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
335 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
336 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
337 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
338 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
339 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
340 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
341 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
342 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
343 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
344 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
345 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
346 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
347 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
348 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
349 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
350 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
351 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
352 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
353 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
354 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
355 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
356 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
357 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
358 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
359 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
360 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
363 #define INIT_FCS 0xFF
364 #define GOOD_FCS 0xCF
366 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
369 * gsm_fcs_add - update FCS
373 * Update the FCS to include c. Uses the algorithm in the specification
377 static inline u8 gsm_fcs_add(u8 fcs, u8 c)
379 return gsm_fcs8[fcs ^ c];
383 * gsm_fcs_add_block - update FCS for a block
386 * @len: length of buffer
388 * Update the FCS to include c. Uses the algorithm in the specification
392 static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
395 fcs = gsm_fcs8[fcs ^ *c++];
400 * gsm_read_ea - read a byte into an EA
401 * @val: variable holding value
402 * c: byte going into the EA
404 * Processes one byte of an EA. Updates the passed variable
405 * and returns 1 if the EA is now completely read
408 static int gsm_read_ea(unsigned int *val, u8 c)
410 /* Add the next 7 bits into the value */
413 /* Was this the last byte of the EA 1 = yes*/
418 * gsm_encode_modem - encode modem data bits
419 * @dlci: DLCI to encode from
421 * Returns the correct GSM encoded modem status bits (6 bit field) for
422 * the current status of the DLCI and attached tty object
425 static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
428 /* FC is true flow control not modem bits */
431 if (dlci->modem_tx & TIOCM_DTR)
432 modembits |= MDM_RTC;
433 if (dlci->modem_tx & TIOCM_RTS)
434 modembits |= MDM_RTR;
435 if (dlci->modem_tx & TIOCM_RI)
437 if (dlci->modem_tx & TIOCM_CD)
443 * gsm_print_packet - display a frame for debug
444 * @hdr: header to print before decode
445 * @addr: address EA from the frame
446 * @cr: C/R bit from the frame
447 * @control: control including PF bit
448 * @data: following data bytes
449 * @dlen: length of data
451 * Displays a packet in human readable format for debugging purposes. The
452 * style is based on amateur radio LAP-B dump display.
455 static void gsm_print_packet(const char *hdr, int addr, int cr,
456 u8 control, const u8 *data, int dlen)
461 pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
463 switch (control & ~PF) {
483 if (!(control & 0x01)) {
484 pr_cont("I N(S)%d N(R)%d",
485 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
486 } else switch (control & 0x0F) {
488 pr_cont("RR(%d)", (control & 0xE0) >> 5);
491 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
494 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
497 pr_cont("[%02X]", control);
506 print_hex_dump_bytes("", DUMP_PREFIX_NONE, data, dlen);
511 * Link level transmission side
515 * gsm_stuff_packet - bytestuff a packet
518 * @len: length of input
520 * Expand a buffer by bytestuffing it. The worst case size change
521 * is doubling and the caller is responsible for handing out
522 * suitable sized buffers.
525 static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
529 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
530 || *input == XON || *input == XOFF) {
531 *output++ = GSM1_ESCAPE;
532 *output++ = *input++ ^ GSM1_ESCAPE_BITS;
535 *output++ = *input++;
542 * gsm_send - send a control frame
544 * @addr: address for control frame
545 * @cr: command/response bit
546 * @control: control byte including PF bit
548 * Format up and transmit a control frame. These do not go via the
549 * queueing logic as they should be transmitted ahead of data when
552 * FIXME: Lock versus data TX path
555 static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
561 switch (gsm->encoding) {
564 cbuf[1] = (addr << 2) | (cr << 1) | EA;
566 cbuf[3] = EA; /* Length of data = 0 */
567 cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
573 /* Control frame + packing (but not frame stuffing) in mode 1 */
574 ibuf[0] = (addr << 2) | (cr << 1) | EA;
576 ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
577 /* Stuffing may double the size worst case */
578 len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
579 /* Now add the SOF markers */
581 cbuf[len + 1] = GSM1_SOF;
582 /* FIXME: we can omit the lead one in many cases */
589 gsmld_output(gsm, cbuf, len);
590 gsm_print_packet("-->", addr, cr, control, NULL, 0);
594 * gsm_response - send a control response
596 * @addr: address for control frame
597 * @control: control byte including PF bit
599 * Format up and transmit a link level response frame.
602 static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
604 gsm_send(gsm, addr, 0, control);
608 * gsm_command - send a control command
610 * @addr: address for control frame
611 * @control: control byte including PF bit
613 * Format up and transmit a link level command frame.
616 static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
618 gsm_send(gsm, addr, 1, control);
621 /* Data transmission */
623 #define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
626 * gsm_data_alloc - allocate data frame
628 * @addr: DLCI address
629 * @len: length excluding header and FCS
630 * @ctrl: control byte
632 * Allocate a new data buffer for sending frames with data. Space is left
633 * at the front for header bytes but that is treated as an implementation
634 * detail and not for the high level code to use
637 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
640 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
644 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */
648 INIT_LIST_HEAD(&m->list);
653 * gsm_data_kick - poke the queue
656 * The tty device has called us to indicate that room has appeared in
657 * the transmit queue. Ram more data into the pipe if we have any
658 * If we have been flow-stopped by a CMD_FCOFF, then we can only
659 * send messages on DLCI0 until CMD_FCON
661 * FIXME: lock against link layer control transmissions
664 static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
666 struct gsm_msg *msg, *nmsg;
669 list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
670 if (gsm->constipated && msg->addr)
672 if (gsm->encoding != 0) {
673 gsm->txframe[0] = GSM1_SOF;
674 len = gsm_stuff_frame(msg->data,
675 gsm->txframe + 1, msg->len);
676 gsm->txframe[len + 1] = GSM1_SOF;
679 gsm->txframe[0] = GSM0_SOF;
680 memcpy(gsm->txframe + 1 , msg->data, msg->len);
681 gsm->txframe[msg->len + 1] = GSM0_SOF;
686 print_hex_dump_bytes("gsm_data_kick: ",
689 if (gsmld_output(gsm, gsm->txframe, len) < 0)
691 /* FIXME: Can eliminate one SOF in many more cases */
692 gsm->tx_bytes -= msg->len;
694 list_del(&msg->list);
698 tty_port_tty_wakeup(&dlci->port);
702 for (i = 0; i < NUM_DLCI; i++)
704 tty_port_tty_wakeup(&gsm->dlci[i]->port);
710 * __gsm_data_queue - queue a UI or UIH frame
711 * @dlci: DLCI sending the data
712 * @msg: message queued
714 * Add data to the transmit queue and try and get stuff moving
715 * out of the mux tty if not already doing so. The Caller must hold
719 static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
721 struct gsm_mux *gsm = dlci->gsm;
723 u8 *fcs = dp + msg->len;
725 /* Fill in the header */
726 if (gsm->encoding == 0) {
728 *--dp = (msg->len << 1) | EA;
730 *--dp = (msg->len >> 7); /* bits 7 - 15 */
731 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
737 *--dp = (msg->addr << 2) | 2 | EA;
739 *--dp = (msg->addr << 2) | EA;
740 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
741 /* Ugly protocol layering violation */
742 if (msg->ctrl == UI || msg->ctrl == (UI|PF))
743 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
746 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
747 msg->data, msg->len);
749 /* Move the header back and adjust the length, also allow for the FCS
750 now tacked on the end */
751 msg->len += (msg->data - dp) + 1;
754 /* Add to the actual output queue */
755 list_add_tail(&msg->list, &gsm->tx_list);
756 gsm->tx_bytes += msg->len;
757 gsm_data_kick(gsm, dlci);
761 * gsm_data_queue - queue a UI or UIH frame
762 * @dlci: DLCI sending the data
763 * @msg: message queued
765 * Add data to the transmit queue and try and get stuff moving
766 * out of the mux tty if not already doing so. Take the
767 * the gsm tx lock and dlci lock.
770 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
773 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
774 __gsm_data_queue(dlci, msg);
775 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
779 * gsm_dlci_data_output - try and push data out of a DLCI
781 * @dlci: the DLCI to pull data from
783 * Pull data from a DLCI and send it into the transmit queue if there
784 * is data. Keep to the MRU of the mux. This path handles the usual tty
785 * interface which is a byte stream with optional modem data.
787 * Caller must hold the tx_lock of the mux.
790 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
794 int len, total_size, size;
795 int h = dlci->adaption - 1;
799 len = kfifo_len(&dlci->fifo);
803 /* MTU/MRU count only the data bits */
809 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
810 /* FIXME: need a timer or something to kick this so it can't
811 get stuck with no work outstanding and no buffer free */
815 switch (dlci->adaption) {
816 case 1: /* Unstructured */
818 case 2: /* Unstructed with modem bits.
819 Always one byte as we never send inline break data */
820 *dp++ = gsm_encode_modem(dlci);
823 WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);
824 __gsm_data_queue(dlci, msg);
827 /* Bytes of data we used up */
832 * gsm_dlci_data_output_framed - try and push data out of a DLCI
834 * @dlci: the DLCI to pull data from
836 * Pull data from a DLCI and send it into the transmit queue if there
837 * is data. Keep to the MRU of the mux. This path handles framed data
838 * queued as skbuffs to the DLCI.
840 * Caller must hold the tx_lock of the mux.
843 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
844 struct gsm_dlci *dlci)
849 int last = 0, first = 0;
852 /* One byte per frame is used for B/F flags */
853 if (dlci->adaption == 4)
856 /* dlci->skb is locked by tx_lock */
857 if (dlci->skb == NULL) {
858 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
859 if (dlci->skb == NULL)
863 len = dlci->skb->len + overhead;
865 /* MTU/MRU count only the data bits */
866 if (len > gsm->mtu) {
867 if (dlci->adaption == 3) {
868 /* Over long frame, bin it */
869 dev_kfree_skb_any(dlci->skb);
877 size = len + overhead;
878 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
880 /* FIXME: need a timer or something to kick this so it can't
881 get stuck with no work outstanding and no buffer free */
883 skb_queue_tail(&dlci->skb_list, dlci->skb);
889 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
890 /* Flag byte to carry the start/end info */
891 *dp++ = last << 7 | first << 6 | 1; /* EA */
894 memcpy(dp, dlci->skb->data, len);
895 skb_pull(dlci->skb, len);
896 __gsm_data_queue(dlci, msg);
898 dev_kfree_skb_any(dlci->skb);
905 * gsm_dlci_data_sweep - look for data to send
908 * Sweep the GSM mux channels in priority order looking for ones with
909 * data to send. We could do with optimising this scan a bit. We aim
910 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
911 * TX_THRESH_LO we get called again
913 * FIXME: We should round robin between groups and in theory you can
914 * renegotiate DLCI priorities with optional stuff. Needs optimising.
917 static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
920 /* Priority ordering: We should do priority with RR of the groups */
923 while (i < NUM_DLCI) {
924 struct gsm_dlci *dlci;
926 if (gsm->tx_bytes > TX_THRESH_HI)
929 if (dlci == NULL || dlci->constipated) {
933 if (dlci->adaption < 3 && !dlci->net)
934 len = gsm_dlci_data_output(gsm, dlci);
936 len = gsm_dlci_data_output_framed(gsm, dlci);
939 /* DLCI empty - try the next */
946 * gsm_dlci_data_kick - transmit if possible
947 * @dlci: DLCI to kick
949 * Transmit data from this DLCI if the queue is empty. We can't rely on
950 * a tty wakeup except when we filled the pipe so we need to fire off
951 * new data ourselves in other cases.
954 static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
959 if (dlci->constipated)
962 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
963 /* If we have nothing running then we need to fire up */
964 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
965 if (dlci->gsm->tx_bytes == 0) {
967 gsm_dlci_data_output_framed(dlci->gsm, dlci);
969 gsm_dlci_data_output(dlci->gsm, dlci);
972 gsm_dlci_data_sweep(dlci->gsm);
973 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
977 * Control message processing
982 * gsm_control_reply - send a response frame to a control
984 * @cmd: the command to use
985 * @data: data to follow encoded info
986 * @dlen: length of data
988 * Encode up and queue a UI/UIH frame containing our response.
991 static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
995 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
998 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
999 msg->data[1] = (dlen << 1) | EA;
1000 memcpy(msg->data + 2, data, dlen);
1001 gsm_data_queue(gsm->dlci[0], msg);
1005 * gsm_process_modem - process received modem status
1006 * @tty: virtual tty bound to the DLCI
1007 * @dlci: DLCI to affect
1008 * @modem: modem bits (full EA)
1010 * Used when a modem control message or line state inline in adaption
1011 * layer 2 is processed. Sort out the local modem state and throttles
1014 static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1015 u32 modem, int clen)
1021 /* The modem status command can either contain one octet (v.24 signals)
1022 or two octets (v.24 signals + break signals). The length field will
1023 either be 2 or 3 respectively. This is specified in section
1024 5.4.6.3.7 of the 27.010 mux spec. */
1027 modem = modem & 0x7f;
1030 modem = (modem >> 7) & 0x7f;
1033 /* Flow control/ready to communicate */
1034 fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1035 if (fc && !dlci->constipated) {
1036 /* Need to throttle our output on this device */
1037 dlci->constipated = true;
1038 } else if (!fc && dlci->constipated) {
1039 dlci->constipated = false;
1040 gsm_dlci_data_kick(dlci);
1043 /* Map modem bits */
1044 if (modem & MDM_RTC)
1045 mlines |= TIOCM_DSR | TIOCM_DTR;
1046 if (modem & MDM_RTR)
1047 mlines |= TIOCM_RTS | TIOCM_CTS;
1053 /* Carrier drop -> hangup */
1055 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1060 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1061 dlci->modem_rx = mlines;
1065 * gsm_control_modem - modem status received
1067 * @data: data following command
1068 * @clen: command length
1070 * We have received a modem status control message. This is used by
1071 * the GSM mux protocol to pass virtual modem line status and optionally
1072 * to indicate break signals. Unpack it, convert to Linux representation
1073 * and if need be stuff a break message down the tty.
1076 static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1078 unsigned int addr = 0;
1079 unsigned int modem = 0;
1080 unsigned int brk = 0;
1081 struct gsm_dlci *dlci;
1083 const u8 *dp = data;
1084 struct tty_struct *tty;
1086 while (gsm_read_ea(&addr, *dp++) == 0) {
1091 /* Must be at least one byte following the EA */
1097 /* Closed port, or invalid ? */
1098 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1100 dlci = gsm->dlci[addr];
1102 while (gsm_read_ea(&modem, *dp++) == 0) {
1109 while (gsm_read_ea(&brk, *dp++) == 0) {
1115 modem |= (brk & 0x7f);
1117 tty = tty_port_tty_get(&dlci->port);
1118 gsm_process_modem(tty, dlci, modem, clen);
1123 gsm_control_reply(gsm, CMD_MSC, data, clen);
1127 * gsm_control_rls - remote line status
1130 * @clen: data length
1132 * The modem sends us a two byte message on the control channel whenever
1133 * it wishes to send us an error state from the virtual link. Stuff
1134 * this into the uplink tty if present
1137 static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1139 struct tty_port *port;
1140 unsigned int addr = 0;
1143 const u8 *dp = data;
1145 while (gsm_read_ea(&addr, *dp++) == 0) {
1150 /* Must be at least one byte following ea */
1155 /* Closed port, or invalid ? */
1156 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1160 if ((bits & 1) == 0)
1163 port = &gsm->dlci[addr]->port;
1166 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1168 tty_insert_flip_char(port, 0, TTY_PARITY);
1170 tty_insert_flip_char(port, 0, TTY_FRAME);
1172 tty_flip_buffer_push(port);
1174 gsm_control_reply(gsm, CMD_RLS, data, clen);
1177 static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1180 * gsm_control_message - DLCI 0 control processing
1182 * @command: the command EA
1183 * @data: data beyond the command/length EAs
1186 * Input processor for control messages from the other end of the link.
1187 * Processes the incoming request and queues a response frame or an
1188 * NSC response if not supported
1191 static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1192 const u8 *data, int clen)
1195 unsigned long flags;
1199 struct gsm_dlci *dlci = gsm->dlci[0];
1200 /* Modem wishes to close down */
1204 gsm_dlci_begin_close(dlci);
1209 /* Modem wishes to test, reply with the data */
1210 gsm_control_reply(gsm, CMD_TEST, data, clen);
1213 /* Modem can accept data again */
1214 gsm->constipated = false;
1215 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1216 /* Kick the link in case it is idling */
1217 spin_lock_irqsave(&gsm->tx_lock, flags);
1218 gsm_data_kick(gsm, NULL);
1219 spin_unlock_irqrestore(&gsm->tx_lock, flags);
1222 /* Modem wants us to STFU */
1223 gsm->constipated = true;
1224 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1227 /* Out of band modem line change indicator for a DLCI */
1228 gsm_control_modem(gsm, data, clen);
1231 /* Out of band error reception for a DLCI */
1232 gsm_control_rls(gsm, data, clen);
1235 /* Modem wishes to enter power saving state */
1236 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1238 /* Optional unsupported commands */
1239 case CMD_PN: /* Parameter negotiation */
1240 case CMD_RPN: /* Remote port negotiation */
1241 case CMD_SNC: /* Service negotiation command */
1243 /* Reply to bad commands with an NSC */
1245 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1251 * gsm_control_response - process a response to our control
1253 * @command: the command (response) EA
1254 * @data: data beyond the command/length EA
1257 * Process a response to an outstanding command. We only allow a single
1258 * control message in flight so this is fairly easy. All the clean up
1259 * is done by the caller, we just update the fields, flag it as done
1263 static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1264 const u8 *data, int clen)
1266 struct gsm_control *ctrl;
1267 unsigned long flags;
1269 spin_lock_irqsave(&gsm->control_lock, flags);
1271 ctrl = gsm->pending_cmd;
1272 /* Does the reply match our command */
1274 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1275 /* Our command was replied to, kill the retry timer */
1276 del_timer(&gsm->t2_timer);
1277 gsm->pending_cmd = NULL;
1278 /* Rejected by the other end */
1279 if (command == CMD_NSC)
1280 ctrl->error = -EOPNOTSUPP;
1282 wake_up(&gsm->event);
1284 spin_unlock_irqrestore(&gsm->control_lock, flags);
1288 * gsm_control_transmit - send control packet
1290 * @ctrl: frame to send
1292 * Send out a pending control command (called under control lock)
1295 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1297 struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
1300 msg->data[0] = (ctrl->cmd << 1) | 2 | EA; /* command */
1301 memcpy(msg->data + 1, ctrl->data, ctrl->len);
1302 gsm_data_queue(gsm->dlci[0], msg);
1306 * gsm_control_retransmit - retransmit a control frame
1307 * @data: pointer to our gsm object
1309 * Called off the T2 timer expiry in order to retransmit control frames
1310 * that have been lost in the system somewhere. The control_lock protects
1311 * us from colliding with another sender or a receive completion event.
1312 * In that situation the timer may still occur in a small window but
1313 * gsm->pending_cmd will be NULL and we just let the timer expire.
1316 static void gsm_control_retransmit(struct timer_list *t)
1318 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
1319 struct gsm_control *ctrl;
1320 unsigned long flags;
1321 spin_lock_irqsave(&gsm->control_lock, flags);
1322 ctrl = gsm->pending_cmd;
1325 if (gsm->cretries == 0) {
1326 gsm->pending_cmd = NULL;
1327 ctrl->error = -ETIMEDOUT;
1329 spin_unlock_irqrestore(&gsm->control_lock, flags);
1330 wake_up(&gsm->event);
1333 gsm_control_transmit(gsm, ctrl);
1334 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1336 spin_unlock_irqrestore(&gsm->control_lock, flags);
1340 * gsm_control_send - send a control frame on DLCI 0
1341 * @gsm: the GSM channel
1342 * @command: command to send including CR bit
1343 * @data: bytes of data (must be kmalloced)
1344 * @len: length of the block to send
1346 * Queue and dispatch a control command. Only one command can be
1347 * active at a time. In theory more can be outstanding but the matching
1348 * gets really complicated so for now stick to one outstanding.
1351 static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1352 unsigned int command, u8 *data, int clen)
1354 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1356 unsigned long flags;
1360 wait_event(gsm->event, gsm->pending_cmd == NULL);
1361 spin_lock_irqsave(&gsm->control_lock, flags);
1362 if (gsm->pending_cmd != NULL) {
1363 spin_unlock_irqrestore(&gsm->control_lock, flags);
1366 ctrl->cmd = command;
1369 gsm->pending_cmd = ctrl;
1371 /* If DLCI0 is in ADM mode skip retries, it won't respond */
1372 if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
1375 gsm->cretries = gsm->n2;
1377 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1378 gsm_control_transmit(gsm, ctrl);
1379 spin_unlock_irqrestore(&gsm->control_lock, flags);
1384 * gsm_control_wait - wait for a control to finish
1386 * @control: control we are waiting on
1388 * Waits for the control to complete or time out. Frees any used
1389 * resources and returns 0 for success, or an error if the remote
1390 * rejected or ignored the request.
1393 static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
1396 wait_event(gsm->event, control->done == 1);
1397 err = control->error;
1404 * DLCI level handling: Needs krefs
1408 * State transitions and timers
1412 * gsm_dlci_close - a DLCI has closed
1413 * @dlci: DLCI that closed
1415 * Perform processing when moving a DLCI into closed state. If there
1416 * is an attached tty this is hung up
1419 static void gsm_dlci_close(struct gsm_dlci *dlci)
1421 del_timer(&dlci->t1);
1423 pr_debug("DLCI %d goes closed.\n", dlci->addr);
1424 dlci->state = DLCI_CLOSED;
1425 if (dlci->addr != 0) {
1426 tty_port_tty_hangup(&dlci->port, false);
1427 kfifo_reset(&dlci->fifo);
1429 dlci->gsm->dead = true;
1430 wake_up(&dlci->gsm->event);
1431 /* A DLCI 0 close is a MUX termination so we need to kick that
1432 back to userspace somehow */
1436 * gsm_dlci_open - a DLCI has opened
1437 * @dlci: DLCI that opened
1439 * Perform processing when moving a DLCI into open state.
1442 static void gsm_dlci_open(struct gsm_dlci *dlci)
1444 /* Note that SABM UA .. SABM UA first UA lost can mean that we go
1446 del_timer(&dlci->t1);
1447 /* This will let a tty open continue */
1448 dlci->state = DLCI_OPEN;
1450 pr_debug("DLCI %d goes open.\n", dlci->addr);
1451 wake_up(&dlci->gsm->event);
1455 * gsm_dlci_t1 - T1 timer expiry
1456 * @dlci: DLCI that opened
1458 * The T1 timer handles retransmits of control frames (essentially of
1459 * SABM and DISC). We resend the command until the retry count runs out
1460 * in which case an opening port goes back to closed and a closing port
1461 * is simply put into closed state (any further frames from the other
1462 * end will get a DM response)
1464 * Some control dlci can stay in ADM mode with other dlci working just
1465 * fine. In that case we can just keep the control dlci open after the
1466 * DLCI_OPENING retries time out.
1469 static void gsm_dlci_t1(struct timer_list *t)
1471 struct gsm_dlci *dlci = from_timer(dlci, t, t1);
1472 struct gsm_mux *gsm = dlci->gsm;
1474 switch (dlci->state) {
1477 if (dlci->retries) {
1478 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1479 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1480 } else if (!dlci->addr && gsm->control == (DM | PF)) {
1482 pr_info("DLCI %d opening in ADM mode.\n",
1484 dlci->mode = DLCI_MODE_ADM;
1485 gsm_dlci_open(dlci);
1487 gsm_dlci_close(dlci);
1493 if (dlci->retries) {
1494 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1495 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1497 gsm_dlci_close(dlci);
1500 pr_debug("%s: unhandled state: %d\n", __func__, dlci->state);
1506 * gsm_dlci_begin_open - start channel open procedure
1507 * @dlci: DLCI to open
1509 * Commence opening a DLCI from the Linux side. We issue SABM messages
1510 * to the modem which should then reply with a UA or ADM, at which point
1511 * we will move into open state. Opening is done asynchronously with retry
1512 * running off timers and the responses.
1515 static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
1517 struct gsm_mux *gsm = dlci->gsm;
1518 if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING)
1520 dlci->retries = gsm->n2;
1521 dlci->state = DLCI_OPENING;
1522 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1523 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1527 * gsm_dlci_begin_close - start channel open procedure
1528 * @dlci: DLCI to open
1530 * Commence closing a DLCI from the Linux side. We issue DISC messages
1531 * to the modem which should then reply with a UA, at which point we
1532 * will move into closed state. Closing is done asynchronously with retry
1533 * off timers. We may also receive a DM reply from the other end which
1534 * indicates the channel was already closed.
1537 static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
1539 struct gsm_mux *gsm = dlci->gsm;
1540 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
1542 dlci->retries = gsm->n2;
1543 dlci->state = DLCI_CLOSING;
1544 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1545 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1549 * gsm_dlci_data - data arrived
1551 * @data: block of bytes received
1552 * @len: length of received block
1554 * A UI or UIH frame has arrived which contains data for a channel
1555 * other than the control channel. If the relevant virtual tty is
1556 * open we shovel the bits down it, if not we drop them.
1559 static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
1562 struct tty_port *port = &dlci->port;
1563 struct tty_struct *tty;
1564 unsigned int modem = 0;
1568 pr_debug("%d bytes for tty\n", len);
1569 switch (dlci->adaption) {
1570 /* Unsupported types */
1571 case 4: /* Packetised interruptible data */
1573 case 3: /* Packetised uininterruptible voice/data */
1575 case 2: /* Asynchronous serial with line state in each frame */
1576 while (gsm_read_ea(&modem, *data++) == 0) {
1581 tty = tty_port_tty_get(port);
1583 gsm_process_modem(tty, dlci, modem, clen);
1587 case 1: /* Line state will go via DLCI 0 controls only */
1589 tty_insert_flip_string(port, data, len);
1590 tty_flip_buffer_push(port);
1595 * gsm_dlci_control - data arrived on control channel
1597 * @data: block of bytes received
1598 * @len: length of received block
1600 * A UI or UIH frame has arrived which contains data for DLCI 0 the
1601 * control channel. This should contain a command EA followed by
1602 * control data bytes. The command EA contains a command/response bit
1603 * and we divide up the work accordingly.
1606 static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
1608 /* See what command is involved */
1609 unsigned int command = 0;
1611 if (gsm_read_ea(&command, *data++) == 1) {
1614 /* FIXME: this is properly an EA */
1616 /* Malformed command ? */
1620 gsm_control_message(dlci->gsm, command,
1623 gsm_control_response(dlci->gsm, command,
1631 * Allocate/Free DLCI channels
1635 * gsm_dlci_alloc - allocate a DLCI
1637 * @addr: address of the DLCI
1639 * Allocate and install a new DLCI object into the GSM mux.
1641 * FIXME: review locking races
1644 static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
1646 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
1649 spin_lock_init(&dlci->lock);
1650 mutex_init(&dlci->mutex);
1651 if (kfifo_alloc(&dlci->fifo, 4096, GFP_KERNEL) < 0) {
1656 skb_queue_head_init(&dlci->skb_list);
1657 timer_setup(&dlci->t1, gsm_dlci_t1, 0);
1658 tty_port_init(&dlci->port);
1659 dlci->port.ops = &gsm_port_ops;
1662 dlci->adaption = gsm->adaption;
1663 dlci->state = DLCI_CLOSED;
1665 dlci->data = gsm_dlci_data;
1667 dlci->data = gsm_dlci_command;
1668 gsm->dlci[addr] = dlci;
1673 * gsm_dlci_free - free DLCI
1674 * @dlci: DLCI to free
1680 static void gsm_dlci_free(struct tty_port *port)
1682 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
1684 del_timer_sync(&dlci->t1);
1685 dlci->gsm->dlci[dlci->addr] = NULL;
1686 kfifo_free(&dlci->fifo);
1687 while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
1688 dev_kfree_skb(dlci->skb);
1692 static inline void dlci_get(struct gsm_dlci *dlci)
1694 tty_port_get(&dlci->port);
1697 static inline void dlci_put(struct gsm_dlci *dlci)
1699 tty_port_put(&dlci->port);
1702 static void gsm_destroy_network(struct gsm_dlci *dlci);
1705 * gsm_dlci_release - release DLCI
1706 * @dlci: DLCI to destroy
1708 * Release a DLCI. Actual free is deferred until either
1709 * mux is closed or tty is closed - whichever is last.
1713 static void gsm_dlci_release(struct gsm_dlci *dlci)
1715 struct tty_struct *tty = tty_port_tty_get(&dlci->port);
1717 mutex_lock(&dlci->mutex);
1718 gsm_destroy_network(dlci);
1719 mutex_unlock(&dlci->mutex);
1723 tty_port_tty_set(&dlci->port, NULL);
1726 dlci->state = DLCI_CLOSED;
1731 * LAPBish link layer logic
1735 * gsm_queue - a GSM frame is ready to process
1736 * @gsm: pointer to our gsm mux
1738 * At this point in time a frame has arrived and been demangled from
1739 * the line encoding. All the differences between the encodings have
1740 * been handled below us and the frame is unpacked into the structures.
1741 * The fcs holds the header FCS but any data FCS must be added here.
1744 static void gsm_queue(struct gsm_mux *gsm)
1746 struct gsm_dlci *dlci;
1749 /* We have to sneak a look at the packet body to do the FCS.
1750 A somewhat layering violation in the spec */
1752 if ((gsm->control & ~PF) == UI)
1753 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
1754 if (gsm->encoding == 0) {
1755 /* WARNING: gsm->received_fcs is used for
1756 gsm->encoding = 0 only.
1757 In this case it contain the last piece of data
1758 required to generate final CRC */
1759 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
1761 if (gsm->fcs != GOOD_FCS) {
1764 pr_debug("BAD FCS %02x\n", gsm->fcs);
1767 address = gsm->address >> 1;
1768 if (address >= NUM_DLCI)
1771 cr = gsm->address & 1; /* C/R bit */
1773 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1775 cr ^= 1 - gsm->initiator; /* Flip so 1 always means command */
1776 dlci = gsm->dlci[address];
1778 switch (gsm->control) {
1783 dlci = gsm_dlci_alloc(gsm, address);
1787 gsm_response(gsm, address, DM);
1789 gsm_response(gsm, address, UA);
1790 gsm_dlci_open(dlci);
1796 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1797 gsm_response(gsm, address, DM);
1800 /* Real close complete */
1801 gsm_response(gsm, address, UA);
1802 gsm_dlci_close(dlci);
1806 if (cr == 0 || dlci == NULL)
1808 switch (dlci->state) {
1810 gsm_dlci_close(dlci);
1813 gsm_dlci_open(dlci);
1816 pr_debug("%s: unhandled state: %d\n", __func__,
1821 case DM: /* DM can be valid unsolicited */
1827 gsm_dlci_close(dlci);
1837 if (dlci == NULL || dlci->state != DLCI_OPEN) {
1838 gsm_command(gsm, address, DM|PF);
1841 dlci->data(dlci, gsm->buf, gsm->len);
1854 * gsm0_receive - perform processing for non-transparency
1855 * @gsm: gsm data for this ldisc instance
1858 * Receive bytes in gsm mode 0
1861 static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
1865 switch (gsm->state) {
1866 case GSM_SEARCH: /* SOF marker */
1867 if (c == GSM0_SOF) {
1868 gsm->state = GSM_ADDRESS;
1871 gsm->fcs = INIT_FCS;
1874 case GSM_ADDRESS: /* Address EA */
1875 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1876 if (gsm_read_ea(&gsm->address, c))
1877 gsm->state = GSM_CONTROL;
1879 case GSM_CONTROL: /* Control Byte */
1880 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1882 gsm->state = GSM_LEN0;
1884 case GSM_LEN0: /* Length EA */
1885 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1886 if (gsm_read_ea(&gsm->len, c)) {
1887 if (gsm->len > gsm->mru) {
1889 gsm->state = GSM_SEARCH;
1894 gsm->state = GSM_FCS;
1896 gsm->state = GSM_DATA;
1899 gsm->state = GSM_LEN1;
1902 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1904 gsm->len |= len << 7;
1905 if (gsm->len > gsm->mru) {
1907 gsm->state = GSM_SEARCH;
1912 gsm->state = GSM_FCS;
1914 gsm->state = GSM_DATA;
1916 case GSM_DATA: /* Data */
1917 gsm->buf[gsm->count++] = c;
1918 if (gsm->count == gsm->len)
1919 gsm->state = GSM_FCS;
1921 case GSM_FCS: /* FCS follows the packet */
1922 gsm->received_fcs = c;
1924 gsm->state = GSM_SSOF;
1927 if (c == GSM0_SOF) {
1928 gsm->state = GSM_SEARCH;
1933 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
1939 * gsm1_receive - perform processing for non-transparency
1940 * @gsm: gsm data for this ldisc instance
1943 * Receive bytes in mode 1 (Advanced option)
1946 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
1948 if (c == GSM1_SOF) {
1949 /* EOF is only valid in frame if we have got to the data state
1950 and received at least one byte (the FCS) */
1951 if (gsm->state == GSM_DATA && gsm->count) {
1952 /* Extract the FCS */
1954 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
1955 gsm->len = gsm->count;
1957 gsm->state = GSM_START;
1960 /* Any partial frame was a runt so go back to start */
1961 if (gsm->state != GSM_START) {
1963 gsm->state = GSM_START;
1965 /* A SOF in GSM_START means we are still reading idling or
1970 if (c == GSM1_ESCAPE) {
1975 /* Only an unescaped SOF gets us out of GSM search */
1976 if (gsm->state == GSM_SEARCH)
1980 c ^= GSM1_ESCAPE_BITS;
1981 gsm->escape = false;
1983 switch (gsm->state) {
1984 case GSM_START: /* First byte after SOF */
1986 gsm->state = GSM_ADDRESS;
1987 gsm->fcs = INIT_FCS;
1989 case GSM_ADDRESS: /* Address continuation */
1990 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1991 if (gsm_read_ea(&gsm->address, c))
1992 gsm->state = GSM_CONTROL;
1994 case GSM_CONTROL: /* Control Byte */
1995 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1998 gsm->state = GSM_DATA;
2000 case GSM_DATA: /* Data */
2001 if (gsm->count > gsm->mru) { /* Allow one for the FCS */
2002 gsm->state = GSM_OVERRUN;
2005 gsm->buf[gsm->count++] = c;
2007 case GSM_OVERRUN: /* Over-long - eg a dropped SOF */
2010 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2016 * gsm_error - handle tty error
2018 * @data: byte received (may be invalid)
2019 * @flag: error received
2021 * Handle an error in the receipt of data for a frame. Currently we just
2022 * go back to hunting for a SOF.
2024 * FIXME: better diagnostics ?
2027 static void gsm_error(struct gsm_mux *gsm,
2028 unsigned char data, unsigned char flag)
2030 gsm->state = GSM_SEARCH;
2034 static int gsm_disconnect(struct gsm_mux *gsm)
2036 struct gsm_dlci *dlci = gsm->dlci[0];
2037 struct gsm_control *gc;
2042 /* In theory disconnecting DLCI 0 is sufficient but for some
2043 modems this is apparently not the case. */
2044 gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
2046 gsm_control_wait(gsm, gc);
2048 del_timer_sync(&gsm->t2_timer);
2049 /* Now we are sure T2 has stopped */
2051 gsm_dlci_begin_close(dlci);
2052 wait_event_interruptible(gsm->event,
2053 dlci->state == DLCI_CLOSED);
2055 if (signal_pending(current))
2062 * gsm_cleanup_mux - generic GSM protocol cleanup
2065 * Clean up the bits of the mux which are the same for all framing
2066 * protocols. Remove the mux from the mux table, stop all the timers
2067 * and then shut down each device hanging up the channels as we go.
2070 static void gsm_cleanup_mux(struct gsm_mux *gsm)
2073 struct gsm_dlci *dlci = gsm->dlci[0];
2074 struct gsm_msg *txq, *ntxq;
2078 spin_lock(&gsm_mux_lock);
2079 for (i = 0; i < MAX_MUX; i++) {
2080 if (gsm_mux[i] == gsm) {
2085 spin_unlock(&gsm_mux_lock);
2086 /* open failed before registering => nothing to do */
2090 del_timer_sync(&gsm->t2_timer);
2091 /* Now we are sure T2 has stopped */
2095 /* Free up any link layer users */
2096 mutex_lock(&gsm->mutex);
2097 for (i = 0; i < NUM_DLCI; i++)
2099 gsm_dlci_release(gsm->dlci[i]);
2100 mutex_unlock(&gsm->mutex);
2101 /* Now wipe the queues */
2102 list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2104 INIT_LIST_HEAD(&gsm->tx_list);
2108 * gsm_activate_mux - generic GSM setup
2111 * Set up the bits of the mux which are the same for all framing
2112 * protocols. Add the mux to the mux table so it can be opened and
2113 * finally kick off connecting to DLCI 0 on the modem.
2116 static int gsm_activate_mux(struct gsm_mux *gsm)
2118 struct gsm_dlci *dlci;
2121 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
2122 init_waitqueue_head(&gsm->event);
2123 spin_lock_init(&gsm->control_lock);
2124 spin_lock_init(&gsm->tx_lock);
2126 if (gsm->encoding == 0)
2127 gsm->receive = gsm0_receive;
2129 gsm->receive = gsm1_receive;
2131 spin_lock(&gsm_mux_lock);
2132 for (i = 0; i < MAX_MUX; i++) {
2133 if (gsm_mux[i] == NULL) {
2139 spin_unlock(&gsm_mux_lock);
2143 dlci = gsm_dlci_alloc(gsm, 0);
2146 gsm->dead = false; /* Tty opens are now permissible */
2151 * gsm_free_mux - free up a mux
2154 * Dispose of allocated resources for a dead mux
2156 static void gsm_free_mux(struct gsm_mux *gsm)
2158 kfree(gsm->txframe);
2164 * gsm_free_muxr - free up a mux
2167 * Dispose of allocated resources for a dead mux
2169 static void gsm_free_muxr(struct kref *ref)
2171 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2175 static inline void mux_get(struct gsm_mux *gsm)
2177 kref_get(&gsm->ref);
2180 static inline void mux_put(struct gsm_mux *gsm)
2182 kref_put(&gsm->ref, gsm_free_muxr);
2185 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
2187 return gsm->num * NUM_DLCI;
2190 static inline unsigned int mux_line_to_num(unsigned int line)
2192 return line / NUM_DLCI;
2196 * gsm_alloc_mux - allocate a mux
2198 * Creates a new mux ready for activation.
2201 static struct gsm_mux *gsm_alloc_mux(void)
2203 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2206 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2207 if (gsm->buf == NULL) {
2211 gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
2212 if (gsm->txframe == NULL) {
2217 spin_lock_init(&gsm->lock);
2218 mutex_init(&gsm->mutex);
2219 kref_init(&gsm->ref);
2220 INIT_LIST_HEAD(&gsm->tx_list);
2228 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
2230 gsm->dead = true; /* Avoid early tty opens */
2235 static void gsm_copy_config_values(struct gsm_mux *gsm,
2236 struct gsm_config *c)
2238 memset(c, 0, sizeof(*c));
2239 c->adaption = gsm->adaption;
2240 c->encapsulation = gsm->encoding;
2241 c->initiator = gsm->initiator;
2244 c->t3 = 0; /* Not supported */
2246 if (gsm->ftype == UIH)
2250 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
2256 static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
2259 int need_restart = 0;
2261 /* Stuff we don't support yet - UI or I frame transport, windowing */
2262 if ((c->adaption != 1 && c->adaption != 2) || c->k)
2264 /* Check the MRU/MTU range looks sane */
2265 if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2269 if (c->encapsulation > 1) /* Basic, advanced, no I */
2271 if (c->initiator > 1)
2273 if (c->i == 0 || c->i > 2) /* UIH and UI only */
2276 * See what is needed for reconfiguration
2280 if (c->t1 != 0 && c->t1 != gsm->t1)
2282 if (c->t2 != 0 && c->t2 != gsm->t2)
2284 if (c->encapsulation != gsm->encoding)
2286 if (c->adaption != gsm->adaption)
2289 if (c->initiator != gsm->initiator)
2291 if (c->mru != gsm->mru)
2293 if (c->mtu != gsm->mtu)
2297 * Close down what is needed, restart and initiate the new
2301 if (need_close || need_restart) {
2304 ret = gsm_disconnect(gsm);
2310 gsm_cleanup_mux(gsm);
2312 gsm->initiator = c->initiator;
2315 gsm->encoding = c->encapsulation;
2316 gsm->adaption = c->adaption;
2330 * FIXME: We need to separate activation/deactivation from adding
2331 * and removing from the mux array
2334 gsm_activate_mux(gsm);
2335 if (gsm->initiator && need_close)
2336 gsm_dlci_begin_open(gsm->dlci[0]);
2341 * gsmld_output - write to link
2343 * @data: bytes to output
2346 * Write a block of data from the GSM mux to the data channel. This
2347 * will eventually be serialized from above but at the moment isn't.
2350 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2352 if (tty_write_room(gsm->tty) < len) {
2353 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2357 print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET,
2359 gsm->tty->ops->write(gsm->tty, data, len);
2364 * gsmld_attach_gsm - mode set up
2365 * @tty: our tty structure
2368 * Set up the MUX for basic mode and commence connecting to the
2369 * modem. Currently called from the line discipline set up but
2370 * will need moving to an ioctl path.
2373 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2378 gsm->tty = tty_kref_get(tty);
2379 ret = gsm_activate_mux(gsm);
2381 tty_kref_put(gsm->tty);
2383 /* Don't register device 0 - this is the control channel and not
2384 a usable tty interface */
2385 base = mux_num_to_base(gsm); /* Base for this MUX */
2386 for (i = 1; i < NUM_DLCI; i++)
2387 tty_register_device(gsm_tty_driver, base + i, NULL);
2394 * gsmld_detach_gsm - stop doing 0710 mux
2395 * @tty: tty attached to the mux
2398 * Shutdown and then clean up the resources used by the line discipline
2401 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2403 unsigned int base = mux_num_to_base(gsm); /* Base for this MUX */
2406 WARN_ON(tty != gsm->tty);
2407 for (i = 1; i < NUM_DLCI; i++)
2408 tty_unregister_device(gsm_tty_driver, base + i);
2409 gsm_cleanup_mux(gsm);
2410 tty_kref_put(gsm->tty);
2414 static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2415 char *fp, int count)
2417 struct gsm_mux *gsm = tty->disc_data;
2418 const unsigned char *dp;
2421 char flags = TTY_NORMAL;
2424 print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
2427 for (i = count, dp = cp, f = fp; i; i--, dp++) {
2432 gsm->receive(gsm, *dp);
2438 gsm_error(gsm, *dp, flags);
2441 WARN_ONCE(1, "%s: unknown flag %d\n",
2442 tty_name(tty), flags);
2446 /* FASYNC if needed ? */
2447 /* If clogged call tty_throttle(tty); */
2451 * gsmld_flush_buffer - clean input queue
2452 * @tty: terminal device
2454 * Flush the input buffer. Called when the line discipline is
2455 * being closed, when the tty layer wants the buffer flushed (eg
2459 static void gsmld_flush_buffer(struct tty_struct *tty)
2464 * gsmld_close - close the ldisc for this tty
2467 * Called from the terminal layer when this line discipline is
2468 * being shut down, either because of a close or becsuse of a
2469 * discipline change. The function will not be called while other
2470 * ldisc methods are in progress.
2473 static void gsmld_close(struct tty_struct *tty)
2475 struct gsm_mux *gsm = tty->disc_data;
2477 gsmld_detach_gsm(tty, gsm);
2479 gsmld_flush_buffer(tty);
2480 /* Do other clean up here */
2485 * gsmld_open - open an ldisc
2486 * @tty: terminal to open
2488 * Called when this line discipline is being attached to the
2489 * terminal device. Can sleep. Called serialized so that no
2490 * other events will occur in parallel. No further open will occur
2494 static int gsmld_open(struct tty_struct *tty)
2496 struct gsm_mux *gsm;
2499 if (tty->ops->write == NULL)
2502 /* Attach our ldisc data */
2503 gsm = gsm_alloc_mux();
2507 tty->disc_data = gsm;
2508 tty->receive_room = 65536;
2510 /* Attach the initial passive connection */
2513 ret = gsmld_attach_gsm(tty, gsm);
2515 gsm_cleanup_mux(gsm);
2522 * gsmld_write_wakeup - asynchronous I/O notifier
2525 * Required for the ptys, serial driver etc. since processes
2526 * that attach themselves to the master and rely on ASYNC
2527 * IO must be woken up
2530 static void gsmld_write_wakeup(struct tty_struct *tty)
2532 struct gsm_mux *gsm = tty->disc_data;
2533 unsigned long flags;
2536 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2537 spin_lock_irqsave(&gsm->tx_lock, flags);
2538 gsm_data_kick(gsm, NULL);
2539 if (gsm->tx_bytes < TX_THRESH_LO) {
2540 gsm_dlci_data_sweep(gsm);
2542 spin_unlock_irqrestore(&gsm->tx_lock, flags);
2546 * gsmld_read - read function for tty
2548 * @file: file object
2549 * @buf: userspace buffer pointer
2552 * Perform reads for the line discipline. We are guaranteed that the
2553 * line discipline will not be closed under us but we may get multiple
2554 * parallel readers and must handle this ourselves. We may also get
2555 * a hangup. Always called in user context, may sleep.
2557 * This code must be sure never to sleep through a hangup.
2560 static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2561 unsigned char __user *buf, size_t nr)
2567 * gsmld_write - write function for tty
2569 * @file: file object
2570 * @buf: userspace buffer pointer
2573 * Called when the owner of the device wants to send a frame
2574 * itself (or some other control data). The data is transferred
2575 * as-is and must be properly framed and checksummed as appropriate
2576 * by userspace. Frames are either sent whole or not at all as this
2577 * avoids pain user side.
2580 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2581 const unsigned char *buf, size_t nr)
2583 int space = tty_write_room(tty);
2585 return tty->ops->write(tty, buf, nr);
2586 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2591 * gsmld_poll - poll method for N_GSM0710
2592 * @tty: terminal device
2593 * @file: file accessing it
2596 * Called when the line discipline is asked to poll() for data or
2597 * for special events. This code is not serialized with respect to
2598 * other events save open/close.
2600 * This code must be sure never to sleep through a hangup.
2601 * Called without the kernel lock held - fine
2604 static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
2608 struct gsm_mux *gsm = tty->disc_data;
2610 poll_wait(file, &tty->read_wait, wait);
2611 poll_wait(file, &tty->write_wait, wait);
2612 if (tty_hung_up_p(file))
2614 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2615 mask |= EPOLLOUT | EPOLLWRNORM;
2621 static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
2622 unsigned int cmd, unsigned long arg)
2624 struct gsm_config c;
2625 struct gsm_mux *gsm = tty->disc_data;
2629 case GSMIOC_GETCONF:
2630 gsm_copy_config_values(gsm, &c);
2631 if (copy_to_user((void __user *)arg, &c, sizeof(c)))
2634 case GSMIOC_SETCONF:
2635 if (copy_from_user(&c, (void __user *)arg, sizeof(c)))
2637 return gsm_config(gsm, &c);
2638 case GSMIOC_GETFIRST:
2639 base = mux_num_to_base(gsm);
2640 return put_user(base + 1, (__u32 __user *)arg);
2642 return n_tty_ioctl_helper(tty, file, cmd, arg);
2651 static int gsm_mux_net_open(struct net_device *net)
2653 pr_debug("%s called\n", __func__);
2654 netif_start_queue(net);
2658 static int gsm_mux_net_close(struct net_device *net)
2660 netif_stop_queue(net);
2664 static void dlci_net_free(struct gsm_dlci *dlci)
2670 dlci->adaption = dlci->prev_adaption;
2671 dlci->data = dlci->prev_data;
2672 free_netdev(dlci->net);
2675 static void net_free(struct kref *ref)
2677 struct gsm_mux_net *mux_net;
2678 struct gsm_dlci *dlci;
2680 mux_net = container_of(ref, struct gsm_mux_net, ref);
2681 dlci = mux_net->dlci;
2684 unregister_netdev(dlci->net);
2685 dlci_net_free(dlci);
2689 static inline void muxnet_get(struct gsm_mux_net *mux_net)
2691 kref_get(&mux_net->ref);
2694 static inline void muxnet_put(struct gsm_mux_net *mux_net)
2696 kref_put(&mux_net->ref, net_free);
2699 static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
2700 struct net_device *net)
2702 struct gsm_mux_net *mux_net = netdev_priv(net);
2703 struct gsm_dlci *dlci = mux_net->dlci;
2704 muxnet_get(mux_net);
2706 skb_queue_head(&dlci->skb_list, skb);
2707 net->stats.tx_packets++;
2708 net->stats.tx_bytes += skb->len;
2709 gsm_dlci_data_kick(dlci);
2710 /* And tell the kernel when the last transmit started. */
2711 netif_trans_update(net);
2712 muxnet_put(mux_net);
2713 return NETDEV_TX_OK;
2716 /* called when a packet did not ack after watchdogtimeout */
2717 static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue)
2719 /* Tell syslog we are hosed. */
2720 dev_dbg(&net->dev, "Tx timed out.\n");
2722 /* Update statistics */
2723 net->stats.tx_errors++;
2726 static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2727 const unsigned char *in_buf, int size)
2729 struct net_device *net = dlci->net;
2730 struct sk_buff *skb;
2731 struct gsm_mux_net *mux_net = netdev_priv(net);
2732 muxnet_get(mux_net);
2734 /* Allocate an sk_buff */
2735 skb = dev_alloc_skb(size + NET_IP_ALIGN);
2737 /* We got no receive buffer. */
2738 net->stats.rx_dropped++;
2739 muxnet_put(mux_net);
2742 skb_reserve(skb, NET_IP_ALIGN);
2743 skb_put_data(skb, in_buf, size);
2746 skb->protocol = htons(ETH_P_IP);
2748 /* Ship it off to the kernel */
2751 /* update out statistics */
2752 net->stats.rx_packets++;
2753 net->stats.rx_bytes += size;
2754 muxnet_put(mux_net);
2758 static void gsm_mux_net_init(struct net_device *net)
2760 static const struct net_device_ops gsm_netdev_ops = {
2761 .ndo_open = gsm_mux_net_open,
2762 .ndo_stop = gsm_mux_net_close,
2763 .ndo_start_xmit = gsm_mux_net_start_xmit,
2764 .ndo_tx_timeout = gsm_mux_net_tx_timeout,
2767 net->netdev_ops = &gsm_netdev_ops;
2769 /* fill in the other fields */
2770 net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2771 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2772 net->type = ARPHRD_NONE;
2773 net->tx_queue_len = 10;
2777 /* caller holds the dlci mutex */
2778 static void gsm_destroy_network(struct gsm_dlci *dlci)
2780 struct gsm_mux_net *mux_net;
2782 pr_debug("destroy network interface\n");
2785 mux_net = netdev_priv(dlci->net);
2786 muxnet_put(mux_net);
2790 /* caller holds the dlci mutex */
2791 static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2795 struct net_device *net;
2796 struct gsm_mux_net *mux_net;
2798 if (!capable(CAP_NET_ADMIN))
2801 /* Already in a non tty mode */
2802 if (dlci->adaption > 2)
2805 if (nc->protocol != htons(ETH_P_IP))
2806 return -EPROTONOSUPPORT;
2808 if (nc->adaption != 3 && nc->adaption != 4)
2809 return -EPROTONOSUPPORT;
2811 pr_debug("create network interface\n");
2814 if (nc->if_name[0] != '\0')
2815 netname = nc->if_name;
2816 net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
2817 NET_NAME_UNKNOWN, gsm_mux_net_init);
2819 pr_err("alloc_netdev failed\n");
2822 net->mtu = dlci->gsm->mtu;
2824 net->max_mtu = dlci->gsm->mtu;
2825 mux_net = netdev_priv(net);
2826 mux_net->dlci = dlci;
2827 kref_init(&mux_net->ref);
2828 strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
2830 /* reconfigure dlci for network */
2831 dlci->prev_adaption = dlci->adaption;
2832 dlci->prev_data = dlci->data;
2833 dlci->adaption = nc->adaption;
2834 dlci->data = gsm_mux_rx_netchar;
2837 pr_debug("register netdev\n");
2838 retval = register_netdev(net);
2840 pr_err("network register fail %d\n", retval);
2841 dlci_net_free(dlci);
2844 return net->ifindex; /* return network index */
2847 /* Line discipline for real tty */
2848 static struct tty_ldisc_ops tty_ldisc_packet = {
2849 .owner = THIS_MODULE,
2850 .magic = TTY_LDISC_MAGIC,
2853 .close = gsmld_close,
2854 .flush_buffer = gsmld_flush_buffer,
2856 .write = gsmld_write,
2857 .ioctl = gsmld_ioctl,
2859 .receive_buf = gsmld_receive_buf,
2860 .write_wakeup = gsmld_write_wakeup
2869 static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
2872 struct gsm_control *ctrl;
2878 modembits[0] = len << 1 | EA; /* Data bytes */
2879 modembits[1] = dlci->addr << 2 | 3; /* DLCI, EA, 1 */
2880 modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
2882 modembits[3] = brk << 4 | 2 | EA; /* Valid, EA */
2883 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
2886 return gsm_control_wait(dlci->gsm, ctrl);
2889 static int gsm_carrier_raised(struct tty_port *port)
2891 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2892 struct gsm_mux *gsm = dlci->gsm;
2894 /* Not yet open so no carrier info */
2895 if (dlci->state != DLCI_OPEN)
2901 * Basic mode with control channel in ADM mode may not respond
2902 * to CMD_MSC at all and modem_rx is empty.
2904 if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
2908 return dlci->modem_rx & TIOCM_CD;
2911 static void gsm_dtr_rts(struct tty_port *port, int onoff)
2913 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2914 unsigned int modem_tx = dlci->modem_tx;
2916 modem_tx |= TIOCM_DTR | TIOCM_RTS;
2918 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
2919 if (modem_tx != dlci->modem_tx) {
2920 dlci->modem_tx = modem_tx;
2921 gsmtty_modem_update(dlci, 0);
2925 static const struct tty_port_operations gsm_port_ops = {
2926 .carrier_raised = gsm_carrier_raised,
2927 .dtr_rts = gsm_dtr_rts,
2928 .destruct = gsm_dlci_free,
2931 static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
2933 struct gsm_mux *gsm;
2934 struct gsm_dlci *dlci;
2935 unsigned int line = tty->index;
2936 unsigned int mux = mux_line_to_num(line);
2944 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
2945 if (gsm_mux[mux] == NULL)
2947 if (line == 0 || line > 61) /* 62/63 reserved */
2952 /* If DLCI 0 is not yet fully open return an error.
2953 This is ok from a locking
2954 perspective as we don't have to worry about this
2956 mutex_lock(&gsm->mutex);
2957 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
2958 mutex_unlock(&gsm->mutex);
2961 dlci = gsm->dlci[line];
2964 dlci = gsm_dlci_alloc(gsm, line);
2967 mutex_unlock(&gsm->mutex);
2970 ret = tty_port_install(&dlci->port, driver, tty);
2974 mutex_unlock(&gsm->mutex);
2979 dlci_get(gsm->dlci[0]);
2981 tty->driver_data = dlci;
2982 mutex_unlock(&gsm->mutex);
2987 static int gsmtty_open(struct tty_struct *tty, struct file *filp)
2989 struct gsm_dlci *dlci = tty->driver_data;
2990 struct tty_port *port = &dlci->port;
2993 tty_port_tty_set(port, tty);
2996 /* We could in theory open and close before we wait - eg if we get
2997 a DM straight back. This is ok as that will have caused a hangup */
2998 tty_port_set_initialized(port, 1);
2999 /* Start sending off SABM messages */
3000 gsm_dlci_begin_open(dlci);
3001 /* And wait for virtual carrier */
3002 return tty_port_block_til_ready(port, tty, filp);
3005 static void gsmtty_close(struct tty_struct *tty, struct file *filp)
3007 struct gsm_dlci *dlci = tty->driver_data;
3011 if (dlci->state == DLCI_CLOSED)
3013 mutex_lock(&dlci->mutex);
3014 gsm_destroy_network(dlci);
3015 mutex_unlock(&dlci->mutex);
3016 if (tty_port_close_start(&dlci->port, tty, filp) == 0)
3018 gsm_dlci_begin_close(dlci);
3019 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
3020 tty_port_lower_dtr_rts(&dlci->port);
3021 tty_port_close_end(&dlci->port, tty);
3022 tty_port_tty_set(&dlci->port, NULL);
3026 static void gsmtty_hangup(struct tty_struct *tty)
3028 struct gsm_dlci *dlci = tty->driver_data;
3029 if (dlci->state == DLCI_CLOSED)
3031 tty_port_hangup(&dlci->port);
3032 gsm_dlci_begin_close(dlci);
3035 static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
3039 struct gsm_dlci *dlci = tty->driver_data;
3040 if (dlci->state == DLCI_CLOSED)
3042 /* Stuff the bytes into the fifo queue */
3043 sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock);
3044 /* Need to kick the channel */
3045 gsm_dlci_data_kick(dlci);
3049 static int gsmtty_write_room(struct tty_struct *tty)
3051 struct gsm_dlci *dlci = tty->driver_data;
3052 if (dlci->state == DLCI_CLOSED)
3054 return TX_SIZE - kfifo_len(&dlci->fifo);
3057 static int gsmtty_chars_in_buffer(struct tty_struct *tty)
3059 struct gsm_dlci *dlci = tty->driver_data;
3060 if (dlci->state == DLCI_CLOSED)
3062 return kfifo_len(&dlci->fifo);
3065 static void gsmtty_flush_buffer(struct tty_struct *tty)
3067 struct gsm_dlci *dlci = tty->driver_data;
3068 if (dlci->state == DLCI_CLOSED)
3070 /* Caution needed: If we implement reliable transport classes
3071 then the data being transmitted can't simply be junked once
3072 it has first hit the stack. Until then we can just blow it
3074 kfifo_reset(&dlci->fifo);
3075 /* Need to unhook this DLCI from the transmit queue logic */
3078 static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3080 /* The FIFO handles the queue so the kernel will do the right
3081 thing waiting on chars_in_buffer before calling us. No work
3085 static int gsmtty_tiocmget(struct tty_struct *tty)
3087 struct gsm_dlci *dlci = tty->driver_data;
3088 if (dlci->state == DLCI_CLOSED)
3090 return dlci->modem_rx;
3093 static int gsmtty_tiocmset(struct tty_struct *tty,
3094 unsigned int set, unsigned int clear)
3096 struct gsm_dlci *dlci = tty->driver_data;
3097 unsigned int modem_tx = dlci->modem_tx;
3099 if (dlci->state == DLCI_CLOSED)
3104 if (modem_tx != dlci->modem_tx) {
3105 dlci->modem_tx = modem_tx;
3106 return gsmtty_modem_update(dlci, 0);
3112 static int gsmtty_ioctl(struct tty_struct *tty,
3113 unsigned int cmd, unsigned long arg)
3115 struct gsm_dlci *dlci = tty->driver_data;
3116 struct gsm_netconfig nc;
3119 if (dlci->state == DLCI_CLOSED)
3122 case GSMIOC_ENABLE_NET:
3123 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3125 nc.if_name[IFNAMSIZ-1] = '\0';
3126 /* return net interface index or error code */
3127 mutex_lock(&dlci->mutex);
3128 index = gsm_create_network(dlci, &nc);
3129 mutex_unlock(&dlci->mutex);
3130 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3133 case GSMIOC_DISABLE_NET:
3134 if (!capable(CAP_NET_ADMIN))
3136 mutex_lock(&dlci->mutex);
3137 gsm_destroy_network(dlci);
3138 mutex_unlock(&dlci->mutex);
3141 return -ENOIOCTLCMD;
3145 static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3147 struct gsm_dlci *dlci = tty->driver_data;
3148 if (dlci->state == DLCI_CLOSED)
3150 /* For the moment its fixed. In actual fact the speed information
3151 for the virtual channel can be propogated in both directions by
3152 the RPN control message. This however rapidly gets nasty as we
3153 then have to remap modem signals each way according to whether
3154 our virtual cable is null modem etc .. */
3155 tty_termios_copy_hw(&tty->termios, old);
3158 static void gsmtty_throttle(struct tty_struct *tty)
3160 struct gsm_dlci *dlci = tty->driver_data;
3161 if (dlci->state == DLCI_CLOSED)
3164 dlci->modem_tx &= ~TIOCM_DTR;
3165 dlci->throttled = true;
3166 /* Send an MSC with DTR cleared */
3167 gsmtty_modem_update(dlci, 0);
3170 static void gsmtty_unthrottle(struct tty_struct *tty)
3172 struct gsm_dlci *dlci = tty->driver_data;
3173 if (dlci->state == DLCI_CLOSED)
3176 dlci->modem_tx |= TIOCM_DTR;
3177 dlci->throttled = false;
3178 /* Send an MSC with DTR set */
3179 gsmtty_modem_update(dlci, 0);
3182 static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3184 struct gsm_dlci *dlci = tty->driver_data;
3185 int encode = 0; /* Off */
3186 if (dlci->state == DLCI_CLOSED)
3189 if (state == -1) /* "On indefinitely" - we can't encode this
3192 else if (state > 0) {
3193 encode = state / 200; /* mS to encoding */
3195 encode = 0x0F; /* Best effort */
3197 return gsmtty_modem_update(dlci, encode);
3200 static void gsmtty_cleanup(struct tty_struct *tty)
3202 struct gsm_dlci *dlci = tty->driver_data;
3203 struct gsm_mux *gsm = dlci->gsm;
3206 dlci_put(gsm->dlci[0]);
3210 /* Virtual ttys for the demux */
3211 static const struct tty_operations gsmtty_ops = {
3212 .install = gsmtty_install,
3213 .open = gsmtty_open,
3214 .close = gsmtty_close,
3215 .write = gsmtty_write,
3216 .write_room = gsmtty_write_room,
3217 .chars_in_buffer = gsmtty_chars_in_buffer,
3218 .flush_buffer = gsmtty_flush_buffer,
3219 .ioctl = gsmtty_ioctl,
3220 .throttle = gsmtty_throttle,
3221 .unthrottle = gsmtty_unthrottle,
3222 .set_termios = gsmtty_set_termios,
3223 .hangup = gsmtty_hangup,
3224 .wait_until_sent = gsmtty_wait_until_sent,
3225 .tiocmget = gsmtty_tiocmget,
3226 .tiocmset = gsmtty_tiocmset,
3227 .break_ctl = gsmtty_break_ctl,
3228 .cleanup = gsmtty_cleanup,
3233 static int __init gsm_init(void)
3235 /* Fill in our line protocol discipline, and register it */
3236 int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
3238 pr_err("n_gsm: can't register line discipline (err = %d)\n",
3243 gsm_tty_driver = alloc_tty_driver(256);
3244 if (!gsm_tty_driver) {
3245 tty_unregister_ldisc(N_GSM0710);
3246 pr_err("gsm_init: tty allocation failed.\n");
3249 gsm_tty_driver->driver_name = "gsmtty";
3250 gsm_tty_driver->name = "gsmtty";
3251 gsm_tty_driver->major = 0; /* Dynamic */
3252 gsm_tty_driver->minor_start = 0;
3253 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
3254 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3255 gsm_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
3256 | TTY_DRIVER_HARDWARE_BREAK;
3257 gsm_tty_driver->init_termios = tty_std_termios;
3259 gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3260 tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3262 spin_lock_init(&gsm_mux_lock);
3264 if (tty_register_driver(gsm_tty_driver)) {
3265 put_tty_driver(gsm_tty_driver);
3266 tty_unregister_ldisc(N_GSM0710);
3267 pr_err("gsm_init: tty registration failed.\n");
3270 pr_debug("gsm_init: loaded as %d,%d.\n",
3271 gsm_tty_driver->major, gsm_tty_driver->minor_start);
3275 static void __exit gsm_exit(void)
3277 int status = tty_unregister_ldisc(N_GSM0710);
3279 pr_err("n_gsm: can't unregister line discipline (err = %d)\n",
3281 tty_unregister_driver(gsm_tty_driver);
3282 put_tty_driver(gsm_tty_driver);
3285 module_init(gsm_init);
3286 module_exit(gsm_exit);
3289 MODULE_LICENSE("GPL");
3290 MODULE_ALIAS_LDISC(N_GSM0710);