/* * n_gsm.c GSM 0710 tty multiplexor * Copyright (c) 2009/10 Intel Corporation * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE * * * TO DO: * Mostly done: ioctls for setting modes/timing * Partly done: hooks so you can pull off frames to non tty devs * Restart DLCI 0 when it closes ? * Test basic encoding * Improve the tx engine * Resolve tx side locking by adding a queue_head and routing * all control traffic via it * General tidy/document * Review the locking/move to refcounts more (mux now moved to an * alloc/free model ready) * Use newest tty open/close port helpers and install hooks * What to do about power functions ? * Termios setting and negotiation * Do we need a 'which mux are you' ioctl to correlate mux and tty sets * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int debug; module_param(debug, int, 0600); #define T1 (HZ/10) #define T2 (HZ/3) #define N2 3 /* Use long timers for testing at low speed with debug on */ #ifdef DEBUG_TIMING #define T1 HZ #define T2 (2 * HZ) #endif /* * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte * limits so this is plenty */ #define MAX_MRU 512 #define MAX_MTU 512 /* * Each block of data we have queued to go out is in the form of * a gsm_msg which holds everything we need in a link layer independent * format */ struct gsm_msg { struct gsm_msg *next; u8 addr; /* DLCI address + flags */ u8 ctrl; /* Control byte + flags */ unsigned int len; /* Length of data block (can be zero) */ unsigned char *data; /* Points into buffer but not at the start */ unsigned char buffer[0]; }; /* * Each active data link has a gsm_dlci structure associated which ties * the link layer to an optional tty (if the tty side is open). To avoid * complexity right now these are only ever freed up when the mux is * shut down. * * At the moment we don't free DLCI objects until the mux is torn down * this avoid object life time issues but might be worth review later. */ struct gsm_dlci { struct gsm_mux *gsm; int addr; int state; #define DLCI_CLOSED 0 #define DLCI_OPENING 1 /* Sending SABM not seen UA */ #define DLCI_OPEN 2 /* SABM/UA complete */ #define DLCI_CLOSING 3 /* Sending DISC not seen UA/DM */ /* Link layer */ spinlock_t lock; /* Protects the internal state */ struct timer_list t1; /* Retransmit timer for SABM and UA */ int retries; /* Uplink tty if active */ struct tty_port port; /* The tty bound to this DLCI if there is one */ struct kfifo *fifo; /* Queue fifo for the DLCI */ struct kfifo _fifo; /* For new fifo API porting only */ int adaption; /* Adaption layer in use */ u32 modem_rx; /* Our incoming virtual modem lines */ u32 modem_tx; /* Our outgoing modem lines */ int dead; /* Refuse re-open */ /* Flow control */ int throttled; /* Private copy of throttle state */ int constipated; /* Throttle status for outgoing */ /* Packetised I/O */ struct sk_buff *skb; /* Frame being sent */ struct sk_buff_head skb_list; /* Queued frames */ /* Data handling callback */ void (*data)(struct gsm_dlci *dlci, u8 *data, int len); }; /* DLCI 0, 62/63 are special or reseved see gsmtty_open */ #define NUM_DLCI 64 /* * DLCI 0 is used to pass control blocks out of band of the data * flow (and with a higher link priority). One command can be outstanding * at a time and we use this structure to manage them. They are created * and destroyed by the user context, and updated by the receive paths * and timers */ struct gsm_control { u8 cmd; /* Command we are issuing */ u8 *data; /* Data for the command in case we retransmit */ int len; /* Length of block for retransmission */ int done; /* Done flag */ int error; /* Error if any */ }; /* * Each GSM mux we have is represented by this structure. If we are * operating as an ldisc then we use this structure as our ldisc * state. We need to sort out lifetimes and locking with respect * to the gsm mux array. For now we don't free DLCI objects that * have been instantiated until the mux itself is terminated. * * To consider further: tty open versus mux shutdown. */ struct gsm_mux { struct tty_struct *tty; /* The tty our ldisc is bound to */ spinlock_t lock; /* Events on the GSM channel */ wait_queue_head_t event; /* Bits for GSM mode decoding */ /* Framing Layer */ unsigned char *buf; int state; #define GSM_SEARCH 0 #define GSM_START 1 #define GSM_ADDRESS 2 #define GSM_CONTROL 3 #define GSM_LEN 4 #define GSM_DATA 5 #define GSM_FCS 6 #define GSM_OVERRUN 7 #define GSM_LEN0 8 #define GSM_LEN1 9 #define GSM_SSOF 10 unsigned int len; unsigned int address; unsigned int count; int escape; int encoding; u8 control; u8 fcs; u8 received_fcs; u8 *txframe; /* TX framing buffer */ /* Methods for the receiver side */ void (*receive)(struct gsm_mux *gsm, u8 ch); void (*error)(struct gsm_mux *gsm, u8 ch, u8 flag); /* And transmit side */ int (*output)(struct gsm_mux *mux, u8 *data, int len); /* Link Layer */ unsigned int mru; unsigned int mtu; int initiator; /* Did we initiate connection */ int dead; /* Has the mux been shut down */ struct gsm_dlci *dlci[NUM_DLCI]; int constipated; /* Asked by remote to shut up */ spinlock_t tx_lock; unsigned int tx_bytes; /* TX data outstanding */ #define TX_THRESH_HI 8192 #define TX_THRESH_LO 2048 struct gsm_msg *tx_head; /* Pending data packets */ struct gsm_msg *tx_tail; /* Control messages */ struct timer_list t2_timer; /* Retransmit timer for commands */ int cretries; /* Command retry counter */ struct gsm_control *pending_cmd;/* Our current pending command */ spinlock_t control_lock; /* Protects the pending command */ /* Configuration */ int adaption; /* 1 or 2 supported */ u8 ftype; /* UI or UIH */ int t1, t2; /* Timers in 1/100th of a sec */ int n2; /* Retry count */ /* Statistics (not currently exposed) */ unsigned long bad_fcs; unsigned long malformed; unsigned long io_error; unsigned long bad_size; unsigned long unsupported; }; /* * Mux objects - needed so that we can translate a tty index into the * relevant mux and DLCI. */ #define MAX_MUX 4 /* 256 minors */ static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */ static spinlock_t gsm_mux_lock; /* * This section of the driver logic implements the GSM encodings * both the basic and the 'advanced'. Reliable transport is not * supported. */ #define CR 0x02 #define EA 0x01 #define PF 0x10 /* I is special: the rest are ..*/ #define RR 0x01 #define UI 0x03 #define RNR 0x05 #define REJ 0x09 #define DM 0x0F #define SABM 0x2F #define DISC 0x43 #define UA 0x63 #define UIH 0xEF /* Channel commands */ #define CMD_NSC 0x09 #define CMD_TEST 0x11 #define CMD_PSC 0x21 #define CMD_RLS 0x29 #define CMD_FCOFF 0x31 #define CMD_PN 0x41 #define CMD_RPN 0x49 #define CMD_FCON 0x51 #define CMD_CLD 0x61 #define CMD_SNC 0x69 #define CMD_MSC 0x71 /* Virtual modem bits */ #define MDM_FC 0x01 #define MDM_RTC 0x02 #define MDM_RTR 0x04 #define MDM_IC 0x20 #define MDM_DV 0x40 #define GSM0_SOF 0xF9 #define GSM1_SOF 0x7E #define GSM1_ESCAPE 0x7D #define GSM1_ESCAPE_BITS 0x20 #define XON 0x11 #define XOFF 0x13 static const struct tty_port_operations gsm_port_ops; /* * CRC table for GSM 0710 */ static const u8 gsm_fcs8[256] = { 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75, 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B, 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69, 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67, 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D, 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43, 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51, 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F, 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05, 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B, 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19, 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17, 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D, 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33, 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21, 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F, 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95, 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B, 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89, 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87, 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD, 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3, 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1, 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF, 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5, 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB, 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9, 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7, 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD, 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3, 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1, 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF }; #define INIT_FCS 0xFF #define GOOD_FCS 0xCF /** * gsm_fcs_add - update FCS * @fcs: Current FCS * @c: Next data * * Update the FCS to include c. Uses the algorithm in the specification * notes. */ static inline u8 gsm_fcs_add(u8 fcs, u8 c) { return gsm_fcs8[fcs ^ c]; } /** * gsm_fcs_add_block - update FCS for a block * @fcs: Current FCS * @c: buffer of data * @len: length of buffer * * Update the FCS to include c. Uses the algorithm in the specification * notes. */ static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len) { while (len--) fcs = gsm_fcs8[fcs ^ *c++]; return fcs; } /** * gsm_read_ea - read a byte into an EA * @val: variable holding value * c: byte going into the EA * * Processes one byte of an EA. Updates the passed variable * and returns 1 if the EA is now completely read */ static int gsm_read_ea(unsigned int *val, u8 c) { /* Add the next 7 bits into the value */ *val <<= 7; *val |= c >> 1; /* Was this the last byte of the EA 1 = yes*/ return c & EA; } /** * gsm_encode_modem - encode modem data bits * @dlci: DLCI to encode from * * Returns the correct GSM encoded modem status bits (6 bit field) for * the current status of the DLCI and attached tty object */ static u8 gsm_encode_modem(const struct gsm_dlci *dlci) { u8 modembits = 0; /* FC is true flow control not modem bits */ if (dlci->throttled) modembits |= MDM_FC; if (dlci->modem_tx & TIOCM_DTR) modembits |= MDM_RTC; if (dlci->modem_tx & TIOCM_RTS) modembits |= MDM_RTR; if (dlci->modem_tx & TIOCM_RI) modembits |= MDM_IC; if (dlci->modem_tx & TIOCM_CD) modembits |= MDM_DV; return modembits; } /** * gsm_print_packet - display a frame for debug * @hdr: header to print before decode * @addr: address EA from the frame * @cr: C/R bit from the frame * @control: control including PF bit * @data: following data bytes * @dlen: length of data * * Displays a packet in human readable format for debugging purposes. The * style is based on amateur radio LAP-B dump display. */ static void gsm_print_packet(const char *hdr, int addr, int cr, u8 control, const u8 *data, int dlen) { if (!(debug & 1)) return; pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]); switch (control & ~PF) { case SABM: pr_cont("SABM"); break; case UA: pr_cont("UA"); break; case DISC: pr_cont("DISC"); break; case DM: pr_cont("DM"); break; case UI: pr_cont("UI"); break; case UIH: pr_cont("UIH"); break; default: if (!(control & 0x01)) { pr_cont("I N(S)%d N(R)%d", (control & 0x0E) >> 1, (control & 0xE) >> 5); } else switch (control & 0x0F) { case RR: pr_cont("RR(%d)", (control & 0xE0) >> 5); break; case RNR: pr_cont("RNR(%d)", (control & 0xE0) >> 5); break; case REJ: pr_cont("REJ(%d)", (control & 0xE0) >> 5); break; default: pr_cont("[%02X]", control); } } if (control & PF) pr_cont("(P)"); else pr_cont("(F)"); if (dlen) { int ct = 0; while (dlen--) { if (ct % 8 == 0) { pr_cont("\n"); pr_debug(" "); } pr_cont("%02X ", *data++); ct++; } } pr_cont("\n"); } /* * Link level transmission side */ /** * gsm_stuff_packet - bytestuff a packet * @ibuf: input * @obuf: output * @len: length of input * * Expand a buffer by bytestuffing it. The worst case size change * is doubling and the caller is responsible for handing out * suitable sized buffers. */ static int gsm_stuff_frame(const u8 *input, u8 *output, int len) { int olen = 0; while (len--) { if (*input == GSM1_SOF || *input == GSM1_ESCAPE || *input == XON || *input == XOFF) { *output++ = GSM1_ESCAPE; *output++ = *input++ ^ GSM1_ESCAPE_BITS; olen++; } else *output++ = *input++; olen++; } return olen; } static void hex_packet(const unsigned char *p, int len) { int i; for (i = 0; i < len; i++) { if (i && (i % 16) == 0) { pr_cont("\n"); pr_debug(""); } pr_cont("%02X ", *p++); } pr_cont("\n"); } /** * gsm_send - send a control frame * @gsm: our GSM mux * @addr: address for control frame * @cr: command/response bit * @control: control byte including PF bit * * Format up and transmit a control frame. These do not go via the * queueing logic as they should be transmitted ahead of data when * they are needed. * * FIXME: Lock versus data TX path */ static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control) { int len; u8 cbuf[10]; u8 ibuf[3]; switch (gsm->encoding) { case 0: cbuf[0] = GSM0_SOF; cbuf[1] = (addr << 2) | (cr << 1) | EA; cbuf[2] = control; cbuf[3] = EA; /* Length of data = 0 */ cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3); cbuf[5] = GSM0_SOF; len = 6; break; case 1: case 2: /* Control frame + packing (but not frame stuffing) in mode 1 */ ibuf[0] = (addr << 2) | (cr << 1) | EA; ibuf[1] = control; ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2); /* Stuffing may double the size worst case */ len = gsm_stuff_frame(ibuf, cbuf + 1, 3); /* Now add the SOF markers */ cbuf[0] = GSM1_SOF; cbuf[len + 1] = GSM1_SOF; /* FIXME: we can omit the lead one in many cases */ len += 2; break; default: WARN_ON(1); return; } gsm->output(gsm, cbuf, len); gsm_print_packet("-->", addr, cr, control, NULL, 0); } /** * gsm_response - send a control response * @gsm: our GSM mux * @addr: address for control frame * @control: control byte including PF bit * * Format up and transmit a link level response frame. */ static inline void gsm_response(struct gsm_mux *gsm, int addr, int control) { gsm_send(gsm, addr, 0, control); } /** * gsm_command - send a control command * @gsm: our GSM mux * @addr: address for control frame * @control: control byte including PF bit * * Format up and transmit a link level command frame. */ static inline void gsm_command(struct gsm_mux *gsm, int addr, int control) { gsm_send(gsm, addr, 1, control); } /* Data transmission */ #define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */ /** * gsm_data_alloc - allocate data frame * @gsm: GSM mux * @addr: DLCI address * @len: length excluding header and FCS * @ctrl: control byte * * Allocate a new data buffer for sending frames with data. Space is left * at the front for header bytes but that is treated as an implementation * detail and not for the high level code to use */ static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len, u8 ctrl) { struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN, GFP_ATOMIC); if (m == NULL) return NULL; m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */ m->len = len; m->addr = addr; m->ctrl = ctrl; m->next = NULL; return m; } /** * gsm_data_kick - poke the queue * @gsm: GSM Mux * * The tty device has called us to indicate that room has appeared in * the transmit queue. Ram more data into the pipe if we have any * * FIXME: lock against link layer control transmissions */ static void gsm_data_kick(struct gsm_mux *gsm) { struct gsm_msg *msg = gsm->tx_head; int len; int skip_sof = 0; /* FIXME: We need to apply this solely to data messages */ if (gsm->constipated) return; while (gsm->tx_head != NULL) { msg = gsm->tx_head; if (gsm->encoding != 0) { gsm->txframe[0] = GSM1_SOF; len = gsm_stuff_frame(msg->data, gsm->txframe + 1, msg->len); gsm->txframe[len + 1] = GSM1_SOF; len += 2; } else { gsm->txframe[0] = GSM0_SOF; memcpy(gsm->txframe + 1 , msg->data, msg->len); gsm->txframe[msg->len + 1] = GSM0_SOF; len = msg->len + 2; } if (debug & 4) { pr_debug("gsm_data_kick:\n"); hex_packet(gsm->txframe, len); } if (gsm->output(gsm, gsm->txframe + skip_sof, len - skip_sof) < 0) break; /* FIXME: Can eliminate one SOF in many more cases */ gsm->tx_head = msg->next; if (gsm->tx_head == NULL) gsm->tx_tail = NULL; gsm->tx_bytes -= msg->len; kfree(msg); /* For a burst of frames skip the extra SOF within the burst */ skip_sof = 1; } } /** * __gsm_data_queue - queue a UI or UIH frame * @dlci: DLCI sending the data * @msg: message queued * * Add data to the transmit queue and try and get stuff moving * out of the mux tty if not already doing so. The Caller must hold * the gsm tx lock. */ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) { struct gsm_mux *gsm = dlci->gsm; u8 *dp = msg->data; u8 *fcs = dp + msg->len; /* Fill in the header */ if (gsm->encoding == 0) { if (msg->len < 128) *--dp = (msg->len << 1) | EA; else { *--dp = (msg->len >> 7); /* bits 7 - 15 */ *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */ } } *--dp = msg->ctrl; if (gsm->initiator) *--dp = (msg->addr << 2) | 2 | EA; else *--dp = (msg->addr << 2) | EA; *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp); /* Ugly protocol layering violation */ if (msg->ctrl == UI || msg->ctrl == (UI|PF)) *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len); *fcs = 0xFF - *fcs; gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl, msg->data, msg->len); /* Move the header back and adjust the length, also allow for the FCS now tacked on the end */ msg->len += (msg->data - dp) + 1; msg->data = dp; /* Add to the actual output queue */ if (gsm->tx_tail) gsm->tx_tail->next = msg; else gsm->tx_head = msg; gsm->tx_tail = msg; gsm->tx_bytes += msg->len; gsm_data_kick(gsm); } /** * gsm_data_queue - queue a UI or UIH frame * @dlci: DLCI sending the data * @msg: message queued * * Add data to the transmit queue and try and get stuff moving * out of the mux tty if not already doing so. Take the * the gsm tx lock and dlci lock. */ static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) { unsigned long flags; spin_lock_irqsave(&dlci->gsm->tx_lock, flags); __gsm_data_queue(dlci, msg); spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags); } /** * gsm_dlci_data_output - try and push data out of a DLCI * @gsm: mux * @dlci: the DLCI to pull data from * * Pull data from a DLCI and send it into the transmit queue if there * is data. Keep to the MRU of the mux. This path handles the usual tty * interface which is a byte stream with optional modem data. * * Caller must hold the tx_lock of the mux. */ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci) { struct gsm_msg *msg; u8 *dp; int len, size; int h = dlci->adaption - 1; len = kfifo_len(dlci->fifo); if (len == 0) return 0; /* MTU/MRU count only the data bits */ if (len > gsm->mtu) len = gsm->mtu; size = len + h; msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype); /* FIXME: need a timer or something to kick this so it can't get stuck with no work outstanding and no buffer free */ if (msg == NULL) return -ENOMEM; dp = msg->data; switch (dlci->adaption) { case 1: /* Unstructured */ break; case 2: /* Unstructed with modem bits. Always one byte as we never send inline break data */ *dp += gsm_encode_modem(dlci); len--; break; } WARN_ON(kfifo_out_locked(dlci->fifo, dp , len, &dlci->lock) != len); __gsm_data_queue(dlci, msg); /* Bytes of data we used up */ return size; } /** * gsm_dlci_data_output_framed - try and push data out of a DLCI * @gsm: mux * @dlci: the DLCI to pull data from * * Pull data from a DLCI and send it into the transmit queue if there * is data. Keep to the MRU of the mux. This path handles framed data * queued as skbuffs to the DLCI. * * Caller must hold the tx_lock of the mux. */ static int gsm_dlci_data_output_framed(struct gsm_mux *gsm, struct gsm_dlci *dlci) { struct gsm_msg *msg; u8 *dp; int len, size; int last = 0, first = 0; int overhead = 0; /* One byte per frame is used for B/F flags */ if (dlci->adaption == 4) overhead = 1; /* dlci->skb is locked by tx_lock */ if (dlci->skb == NULL) { dlci->skb = skb_dequeue(&dlci->skb_list); if (dlci->skb == NULL) return 0; first = 1; } len = dlci->skb->len + overhead; /* MTU/MRU count only the data bits */ if (len > gsm->mtu) { if (dlci->adaption == 3) { /* Over long frame, bin it */ kfree_skb(dlci->skb); dlci->skb = NULL; return 0; } len = gsm->mtu; } else last = 1; size = len + overhead; msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype); /* FIXME: need a timer or something to kick this so it can't get stuck with no work outstanding and no buffer free */ if (msg == NULL) return -ENOMEM; dp = msg->data; if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */ /* Flag byte to carry the start/end info */ *dp++ = last << 7 | first << 6 | 1; /* EA */ len--; } memcpy(dp, skb_pull(dlci->skb, len), len); __gsm_data_queue(dlci, msg); if (last) dlci->skb = NULL; return size; } /** * gsm_dlci_data_sweep - look for data to send * @gsm: the GSM mux * * Sweep the GSM mux channels in priority order looking for ones with * data to send. We could do with optimising this scan a bit. We aim * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit * TX_THRESH_LO we get called again * * FIXME: We should round robin between groups and in theory you can * renegotiate DLCI priorities with optional stuff. Needs optimising. */ static void gsm_dlci_data_sweep(struct gsm_mux *gsm) { int len; /* Priority ordering: We should do priority with RR of the groups */ int i = 1; while (i < NUM_DLCI) { struct gsm_dlci *dlci; if (gsm->tx_bytes > TX_THRESH_HI) break; dlci = gsm->dlci[i]; if (dlci == NULL || dlci->constipated) { i++; continue; } if (dlci->adaption < 3) len = gsm_dlci_data_output(gsm, dlci); else len = gsm_dlci_data_output_framed(gsm, dlci); if (len < 0) break; /* DLCI empty - try the next */ if (len == 0) i++; } } /** * gsm_dlci_data_kick - transmit if possible * @dlci: DLCI to kick * * Transmit data from this DLCI if the queue is empty. We can't rely on * a tty wakeup except when we filled the pipe so we need to fire off * new data ourselves in other cases. */ static void gsm_dlci_data_kick(struct gsm_dlci *dlci) { unsigned long flags; spin_lock_irqsave(&dlci->gsm->tx_lock, flags); /* If we have nothing running then we need to fire up */ if (dlci->gsm->tx_bytes == 0) gsm_dlci_data_output(dlci->gsm, dlci); else if (dlci->gsm->tx_bytes < TX_THRESH_LO) gsm_dlci_data_sweep(dlci->gsm); spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags); } /* * Control message processing */ /** * gsm_control_reply - send a response frame to a control * @gsm: gsm channel * @cmd: the command to use * @data: data to follow encoded info * @dlen: length of data * * Encode up and queue a UI/UIH frame containing our response. */ static void gsm_control_reply(struct gsm_mux *gsm, int cmd, u8 *data, int dlen) { struct gsm_msg *msg; msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype); if (msg == NULL) return; msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */ msg->data[1] = (dlen << 1) | EA; memcpy(msg->data + 2, data, dlen); gsm_data_queue(gsm->dlci[0], msg); } /** * gsm_process_modem - process received modem status * @tty: virtual tty bound to the DLCI * @dlci: DLCI to affect * @modem: modem bits (full EA) * * Used when a modem control message or line state inline in adaption * layer 2 is processed. Sort out the local modem state and throttles */ static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci, u32 modem) { int mlines = 0; u8 brk = modem >> 6; /* Flow control/ready to communicate */ if (modem & MDM_FC) { /* Need to throttle our output on this device */ dlci->constipated = 1; } if (modem & MDM_RTC) { mlines |= TIOCM_DSR | TIOCM_DTR; dlci->constipated = 0; gsm_dlci_data_kick(dlci); } /* Map modem bits */ if (modem & MDM_RTR) mlines |= TIOCM_RTS | TIOCM_CTS; if (modem & MDM_IC) mlines |= TIOCM_RI; if (modem & MDM_DV) mlines |= TIOCM_CD; /* Carrier drop -> hangup */ if (tty) { if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD)) if (!(tty->termios->c_cflag & CLOCAL)) tty_hangup(tty); if (brk & 0x01) tty_insert_flip_char(tty, 0, TTY_BREAK); } dlci->modem_rx = mlines; } /** * gsm_control_modem - modem status received * @gsm: GSM channel * @data: data following command * @clen: command length * * We have received a modem status control message. This is used by * the GSM mux protocol to pass virtual modem line status and optionally * to indicate break signals. Unpack it, convert to Linux representation * and if need be stuff a break message down the tty. */ static void gsm_control_modem(struct gsm_mux *gsm, u8 *data, int clen) { unsigned int addr = 0; unsigned int modem = 0; struct gsm_dlci *dlci; int len = clen; u8 *dp = data; struct tty_struct *tty; while (gsm_read_ea(&addr, *dp++) == 0) { len--; if (len == 0) return; } /* Must be at least one byte following the EA */ len--; if (len <= 0) return; addr >>= 1; /* Closed port, or invalid ? */ if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL) return; dlci = gsm->dlci[addr]; while (gsm_read_ea(&modem, *dp++) == 0) { len--; if (len == 0) return; } tty = tty_port_tty_get(&dlci->port); gsm_process_modem(tty, dlci, modem); if (tty) { tty_wakeup(tty); tty_kref_put(tty); } gsm_control_reply(gsm, CMD_MSC, data, clen); } /** * gsm_control_rls - remote line status * @gsm: GSM channel * @data: data bytes * @clen: data length * * The modem sends us a two byte message on the control channel whenever * it wishes to send us an error state from the virtual link. Stuff * this into the uplink tty if present */ static void gsm_control_rls(struct gsm_mux *gsm, u8 *data, int clen) { struct tty_struct *tty; unsigned int addr = 0 ; u8 bits; int len = clen; u8 *dp = data; while (gsm_read_ea(&addr, *dp++) == 0) { len--; if (len == 0) return; } /* Must be at least one byte following ea */ len--; if (len <= 0) return; addr >>= 1; /* Closed port, or invalid ? */ if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL) return; /* No error ? */ bits = *dp; if ((bits & 1) == 0) return; /* See if we have an uplink tty */ tty = tty_port_tty_get(&gsm->dlci[addr]->port); if (tty) { if (bits & 2) tty_insert_flip_char(tty, 0, TTY_OVERRUN); if (bits & 4) tty_insert_flip_char(tty, 0, TTY_PARITY); if (bits & 8) tty_insert_flip_char(tty, 0, TTY_FRAME); tty_flip_buffer_push(tty); tty_kref_put(tty); } gsm_control_reply(gsm, CMD_RLS, data, clen); } static void gsm_dlci_begin_close(struct gsm_dlci *dlci); /** * gsm_control_message - DLCI 0 control processing * @gsm: our GSM mux * @command: the command EA * @data: data beyond the command/length EAs * @clen: length * * Input processor for control messages from the other end of the link. * Processes the incoming request and queues a response frame or an * NSC response if not supported */ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command, u8 *data, int clen) { u8 buf[1]; switch (command) { case CMD_CLD: { struct gsm_dlci *dlci = gsm->dlci[0]; /* Modem wishes to close down */ if (dlci) { dlci->dead = 1; gsm->dead = 1; gsm_dlci_begin_close(dlci); } } break; case CMD_TEST: /* Modem wishes to test, reply with the data */ gsm_control_reply(gsm, CMD_TEST, data, clen); break; case CMD_FCON: /* Modem wants us to STFU */ gsm->constipated = 1; gsm_control_reply(gsm, CMD_FCON, NULL, 0); break; case CMD_FCOFF: /* Modem can accept data again */ gsm->constipated = 0; gsm_control_reply(gsm, CMD_FCOFF, NULL, 0); /* Kick the link in case it is idling */ gsm_data_kick(gsm); break; case CMD_MSC: /* Out of band modem line change indicator for a DLCI */ gsm_control_modem(gsm, data, clen); break; case CMD_RLS: /* Out of band error reception for a DLCI */ gsm_control_rls(gsm, data, clen); break; case CMD_PSC: /* Modem wishes to enter power saving state */ gsm_control_reply(gsm, CMD_PSC, NULL, 0); break; /* Optional unsupported commands */ case CMD_PN: /* Parameter negotiation */ case CMD_RPN: /* Remote port negotiation */ case CMD_SNC: /* Service negotiation command */ default: /* Reply to bad commands with an NSC */ buf[0] = command; gsm_control_reply(gsm, CMD_NSC, buf, 1); break; } } /** * gsm_control_response - process a response to our control * @gsm: our GSM mux * @command: the command (response) EA * @data: data beyond the command/length EA * @clen: length * * Process a response to an outstanding command. We only allow a single * control message in flight so this is fairly easy. All the clean up * is done by the caller, we just update the fields, flag it as done * and return */ static void gsm_control_response(struct gsm_mux *gsm, unsigned int command, u8 *data, int clen) { struct gsm_control *ctrl; unsigned long flags; spin_lock_irqsave(&gsm->control_lock, flags); ctrl = gsm->pending_cmd; /* Does the reply match our command */ command |= 1; if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) { /* Our command was replied to, kill the retry timer */ del_timer(&gsm->t2_timer); gsm->pending_cmd = NULL; /* Rejected by the other end */ if (command == CMD_NSC) ctrl->error = -EOPNOTSUPP; ctrl->done = 1; wake_up(&gsm->event); } spin_unlock_irqrestore(&gsm->control_lock, flags); } /** * gsm_control_transmit - send control packet * @gsm: gsm mux * @ctrl: frame to send * * Send out a pending control command (called under control lock) */ static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl) { struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype); if (msg == NULL) return; msg->data[0] = (ctrl->cmd << 1) | 2 | EA; /* command */ memcpy(msg->data + 1, ctrl->data, ctrl->len); gsm_data_queue(gsm->dlci[0], msg); } /** * gsm_control_retransmit - retransmit a control frame * @data: pointer to our gsm object * * Called off the T2 timer expiry in order to retransmit control frames * that have been lost in the system somewhere. The control_lock protects * us from colliding with another sender or a receive completion event. * In that situation the timer may still occur in a small window but * gsm->pending_cmd will be NULL and we just let the timer expire. */ static void gsm_control_retransmit(unsigned long data) { struct gsm_mux *gsm = (struct gsm_mux *)data; struct gsm_control *ctrl; unsigned long flags; spin_lock_irqsave(&gsm->control_lock, flags); ctrl = gsm->pending_cmd; if (ctrl) { gsm->cretries--; if (gsm->cretries == 0) { gsm->pending_cmd = NULL; ctrl->error = -ETIMEDOUT; ctrl->done = 1; spin_unlock_irqrestore(&gsm->control_lock, flags); wake_up(&gsm->event); return; } gsm_control_transmit(gsm, ctrl); mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100); } spin_unlock_irqrestore(&gsm->control_lock, flags); } /** * gsm_control_send - send a control frame on DLCI 0 * @gsm: the GSM channel * @command: command to send including CR bit * @data: bytes of data (must be kmalloced) * @len: length of the block to send * * Queue and dispatch a control command. Only one command can be * active at a time. In theory more can be outstanding but the matching * gets really complicated so for now stick to one outstanding. */ static struct gsm_control *gsm_control_send(struct gsm_mux *gsm, unsigned int command, u8 *data, int clen) { struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control), GFP_KERNEL); unsigned long flags; if (ctrl == NULL) return NULL; retry: wait_event(gsm->event, gsm->pending_cmd == NULL); spin_lock_irqsave(&gsm->control_lock, flags); if (gsm->pending_cmd != NULL) { spin_unlock_irqrestore(&gsm->control_lock, flags); goto retry; } ctrl->cmd = command; ctrl->data = data; ctrl->len = clen; gsm->pending_cmd = ctrl; gsm->cretries = gsm->n2; mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100); gsm_control_transmit(gsm, ctrl); spin_unlock_irqrestore(&gsm->control_lock, flags); return ctrl; } /** * gsm_control_wait - wait for a control to finish * @gsm: GSM mux * @control: control we are waiting on * * Waits for the control to complete or time out. Frees any used * resources and returns 0 for success, or an error if the remote * rejected or ignored the request. */ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control) { int err; wait_event(gsm->event, control->done == 1); err = control->error; kfree(control); return err; } /* * DLCI level handling: Needs krefs */ /* * State transitions and timers */ /** * gsm_dlci_close - a DLCI has closed * @dlci: DLCI that closed * * Perform processing when moving a DLCI into closed state. If there * is an attached tty this is hung up */ static void gsm_dlci_close(struct gsm_dlci *dlci) { del_timer(&dlci->t1); if (debug & 8) pr_debug("DLCI %d goes closed.\n", dlci->addr); dlci->state = DLCI_CLOSED; if (dlci->addr != 0) { struct tty_struct *tty = tty_port_tty_get(&dlci->port); if (tty) { tty_hangup(tty); tty_kref_put(tty); } kfifo_reset(dlci->fifo); } else dlci->gsm->dead = 1; wake_up(&dlci->gsm->event); /* A DLCI 0 close is a MUX termination so we need to kick that back to userspace somehow */ } /** * gsm_dlci_open - a DLCI has opened * @dlci: DLCI that opened * * Perform processing when moving a DLCI into open state. */ static void gsm_dlci_open(struct gsm_dlci *dlci) { /* Note that SABM UA .. SABM UA first UA lost can mean that we go open -> open */ del_timer(&dlci->t1); /* This will let a tty open continue */ dlci->state = DLCI_OPEN; if (debug & 8) pr_debug("DLCI %d goes open.\n", dlci->addr); wake_up(&dlci->gsm->event); } /** * gsm_dlci_t1 - T1 timer expiry * @dlci: DLCI that opened * * The T1 timer handles retransmits of control frames (essentially of * SABM and DISC). We resend the command until the retry count runs out * in which case an opening port goes back to closed and a closing port * is simply put into closed state (any further frames from the other * end will get a DM response) */ static void gsm_dlci_t1(unsigned long data) { struct gsm_dlci *dlci = (struct gsm_dlci *)data; struct gsm_mux *gsm = dlci->gsm; switch (dlci->state) { case DLCI_OPENING: dlci->retries--; if (dlci->retries) { gsm_command(dlci->gsm, dlci->addr, SABM|PF); mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); } else gsm_dlci_close(dlci); break; case DLCI_CLOSING: dlci->retries--; if (dlci->retries) { gsm_command(dlci->gsm, dlci->addr, DISC|PF); mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); } else gsm_dlci_close(dlci); break; } } /** * gsm_dlci_begin_open - start channel open procedure * @dlci: DLCI to open * * Commence opening a DLCI from the Linux side. We issue SABM messages * to the modem which should then reply with a UA, at which point we * will move into open state. Opening is done asynchronously with retry * running off timers and the responses. */ static void gsm_dlci_begin_open(struct gsm_dlci *dlci) { struct gsm_mux *gsm = dlci->gsm; if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING) return; dlci->retries = gsm->n2; dlci->state = DLCI_OPENING; gsm_command(dlci->gsm, dlci->addr, SABM|PF); mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); } /** * gsm_dlci_begin_close - start channel open procedure * @dlci: DLCI to open * * Commence closing a DLCI from the Linux side. We issue DISC messages * to the modem which should then reply with a UA, at which point we * will move into closed state. Closing is done asynchronously with retry * off timers. We may also receive a DM reply from the other end which * indicates the channel was already closed. */ static void gsm_dlci_begin_close(struct gsm_dlci *dlci) { struct gsm_mux *gsm = dlci->gsm; if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING) return; dlci->retries = gsm->n2; dlci->state = DLCI_CLOSING; gsm_command(dlci->gsm, dlci->addr, DISC|PF); mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); } /** * gsm_dlci_data - data arrived * @dlci: channel * @data: block of bytes received * @len: length of received block * * A UI or UIH frame has arrived which contains data for a channel * other than the control channel. If the relevant virtual tty is * open we shovel the bits down it, if not we drop them. */ static void gsm_dlci_data(struct gsm_dlci *dlci, u8 *data, int len) { /* krefs .. */ struct tty_port *port = &dlci->port; struct tty_struct *tty = tty_port_tty_get(port); unsigned int modem = 0; if (debug & 16) pr_debug("%d bytes for tty %p\n", len, tty); if (tty) { switch (dlci->adaption) { /* Unsupported types */ /* Packetised interruptible data */ case 4: break; /* Packetised uininterruptible voice/data */ case 3: break; /* Asynchronous serial with line state in each frame */ case 2: while (gsm_read_ea(&modem, *data++) == 0) { len--; if (len == 0) return; } gsm_process_modem(tty, dlci, modem); /* Line state will go via DLCI 0 controls only */ case 1: default: tty_insert_flip_string(tty, data, len); tty_flip_buffer_push(tty); } tty_kref_put(tty); } } /** * gsm_dlci_control - data arrived on control channel * @dlci: channel * @data: block of bytes received * @len: length of received block * * A UI or UIH frame has arrived which contains data for DLCI 0 the * control channel. This should contain a command EA followed by * control data bytes. The command EA contains a command/response bit * and we divide up the work accordingly. */ static void gsm_dlci_command(struct gsm_dlci *dlci, u8 *data, int len) { /* See what command is involved */ unsigned int command = 0; while (len-- > 0) { if (gsm_read_ea(&command, *data++) == 1) { int clen = *data++; len--; /* FIXME: this is properly an EA */ clen >>= 1; /* Malformed command ? */ if (clen > len) return; if (command & 1) gsm_control_message(dlci->gsm, command, data, clen); else gsm_control_response(dlci->gsm, command, data, clen); return; } } } /* * Allocate/Free DLCI channels */ /** * gsm_dlci_alloc - allocate a DLCI * @gsm: GSM mux * @addr: address of the DLCI * * Allocate and install a new DLCI object into the GSM mux. * * FIXME: review locking races */ static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr) { struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC); if (dlci == NULL) return NULL; spin_lock_init(&dlci->lock); dlci->fifo = &dlci->_fifo; if (kfifo_alloc(&dlci->_fifo, 4096, GFP_KERNEL) < 0) { kfree(dlci); return NULL; } skb_queue_head_init(&dlci->skb_list); init_timer(&dlci->t1); dlci->t1.function = gsm_dlci_t1; dlci->t1.data = (unsigned long)dlci; tty_port_init(&dlci->port); dlci->port.ops = &gsm_port_ops; dlci->gsm = gsm; dlci->addr = addr; dlci->adaption = gsm->adaption; dlci->state = DLCI_CLOSED; if (addr) dlci->data = gsm_dlci_data; else dlci->data = gsm_dlci_command; gsm->dlci[addr] = dlci; return dlci; } /** * gsm_dlci_free - release DLCI * @dlci: DLCI to destroy * * Free up a DLCI. Currently to keep the lifetime rules sane we only * clean up DLCI objects when the MUX closes rather than as the port * is closed down on both the tty and mux levels. * * Can sleep. */ static void gsm_dlci_free(struct gsm_dlci *dlci) { struct tty_struct *tty = tty_port_tty_get(&dlci->port); if (tty) { tty_vhangup(tty); tty_kref_put(tty); } del_timer_sync(&dlci->t1); dlci->gsm->dlci[dlci->addr] = NULL; kfifo_free(dlci->fifo); kfree(dlci); } /* * LAPBish link layer logic */ /** * gsm_queue - a GSM frame is ready to process * @gsm: pointer to our gsm mux * * At this point in time a frame has arrived and been demangled from * the line encoding. All the differences between the encodings have * been handled below us and the frame is unpacked into the structures. * The fcs holds the header FCS but any data FCS must be added here. */ static void gsm_queue(struct gsm_mux *gsm) { struct gsm_dlci *dlci; u8 cr; int address; /* We have to sneak a look at the packet body to do the FCS. A somewhat layering violation in the spec */ if ((gsm->control & ~PF) == UI) gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len); /* generate final CRC with received FCS */ gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs); if (gsm->fcs != GOOD_FCS) { gsm->bad_fcs++; if (debug & 4) pr_debug("BAD FCS %02x\n", gsm->fcs); return; } address = gsm->address >> 1; if (address >= NUM_DLCI) goto invalid; cr = gsm->address & 1; /* C/R bit */ gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len); cr ^= 1 - gsm->initiator; /* Flip so 1 always means command */ dlci = gsm->dlci[address]; switch (gsm->control) { case SABM|PF: if (cr == 0) goto invalid; if (dlci == NULL) dlci = gsm_dlci_alloc(gsm, address); if (dlci == NULL) return; if (dlci->dead) gsm_response(gsm, address, DM); else { gsm_response(gsm, address, UA); gsm_dlci_open(dlci); } break; case DISC|PF: if (cr == 0) goto invalid; if (dlci == NULL || dlci->state == DLCI_CLOSED) { gsm_response(gsm, address, DM); return; } /* Real close complete */ gsm_response(gsm, address, UA); gsm_dlci_close(dlci); break; case UA: case UA|PF: if (cr == 0 || dlci == NULL) break; switch (dlci->state) { case DLCI_CLOSING: gsm_dlci_close(dlci); break; case DLCI_OPENING: gsm_dlci_open(dlci); break; } break; case DM: /* DM can be valid unsolicited */ case DM|PF: if (cr) goto invalid; if (dlci == NULL) return; gsm_dlci_close(dlci); break; case UI: case UI|PF: case UIH: case UIH|PF: #if 0 if (cr) goto invalid; #endif if (dlci == NULL || dlci->state != DLCI_OPEN) { gsm_command(gsm, address, DM|PF); return; } dlci->data(dlci, gsm->buf, gsm->len); break; default: goto invalid; } return; invalid: gsm->malformed++; return; } /** * gsm0_receive - perform processing for non-transparency * @gsm: gsm data for this ldisc instance * @c: character * * Receive bytes in gsm mode 0 */ static void gsm0_receive(struct gsm_mux *gsm, unsigned char c) { unsigned int len; switch (gsm->state) { case GSM_SEARCH: /* SOF marker */ if (c == GSM0_SOF) { gsm->state = GSM_ADDRESS; gsm->address = 0; gsm->len = 0; gsm->fcs = INIT_FCS; } break; case GSM_ADDRESS: /* Address EA */ gsm->fcs = gsm_fcs_add(gsm->fcs, c); if (gsm_read_ea(&gsm->address, c)) gsm->state = GSM_CONTROL; break; case GSM_CONTROL: /* Control Byte */ gsm->fcs = gsm_fcs_add(gsm->fcs, c); gsm->control = c; gsm->state = GSM_LEN0; break; case GSM_LEN0: /* Length EA */ gsm->fcs = gsm_fcs_add(gsm->fcs, c); if (gsm_read_ea(&gsm->len, c)) { if (gsm->len > gsm->mru) { gsm->bad_size++; gsm->state = GSM_SEARCH; break; } gsm->count = 0; if (!gsm->len) gsm->state = GSM_FCS; else gsm->state = GSM_DATA; break; } gsm->state = GSM_LEN1; break; case GSM_LEN1: gsm->fcs = gsm_fcs_add(gsm->fcs, c); len = c; gsm->len |= len << 7; if (gsm->len > gsm->mru) { gsm->bad_size++; gsm->state = GSM_SEARCH; break; } gsm->count = 0; if (!gsm->len) gsm->state = GSM_FCS; else gsm->state = GSM_DATA; break; case GSM_DATA: /* Data */ gsm->buf[gsm->count++] = c; if (gsm->count == gsm->len) gsm->state = GSM_FCS; break; case GSM_FCS: /* FCS follows the packet */ gsm->received_fcs = c; if (c == GSM0_SOF) { gsm->state = GSM_SEARCH; break; } gsm_queue(gsm); gsm->state = GSM_SSOF; break; case GSM_SSOF: if (c == GSM0_SOF) { gsm->state = GSM_SEARCH; break; } break; } } /** * gsm1_receive - perform processing for non-transparency * @gsm: gsm data for this ldisc instance * @c: character * * Receive bytes in mode 1 (Advanced option) */ static void gsm1_receive(struct gsm_mux *gsm, unsigned char c) { if (c == GSM1_SOF) { /* EOF is only valid in frame if we have got to the data state and received at least one byte (the FCS) */ if (gsm->state == GSM_DATA && gsm->count) { /* Extract the FCS */ gsm->count--; gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]); gsm->len = gsm->count; gsm_queue(gsm); gsm->state = GSM_START; return; } /* Any partial frame was a runt so go back to start */ if (gsm->state != GSM_START) { gsm->malformed++; gsm->state = GSM_START; } /* A SOF in GSM_START means we are still reading idling or framing bytes */ return; } if (c == GSM1_ESCAPE) { gsm->escape = 1; return; } /* Only an unescaped SOF gets us out of GSM search */ if (gsm->state == GSM_SEARCH) return; if (gsm->escape) { c ^= GSM1_ESCAPE_BITS; gsm->escape = 0; } switch (gsm->state) { case GSM_START: /* First byte after SOF */ gsm->address = 0; gsm->state = GSM_ADDRESS; gsm->fcs = INIT_FCS; /* Drop through */ case GSM_ADDRESS: /* Address continuation */ gsm->fcs = gsm_fcs_add(gsm->fcs, c); if (gsm_read_ea(&gsm->address, c)) gsm->state = GSM_CONTROL; break; case GSM_CONTROL: /* Control Byte */ gsm->fcs = gsm_fcs_add(gsm->fcs, c); gsm->control = c; gsm->count = 0; gsm->state = GSM_DATA; break; case GSM_DATA: /* Data */ if (gsm->count > gsm->mru) { /* Allow one for the FCS */ gsm->state = GSM_OVERRUN; gsm->bad_size++; } else gsm->buf[gsm->count++] = c; break; case GSM_OVERRUN: /* Over-long - eg a dropped SOF */ break; } } /** * gsm_error - handle tty error * @gsm: ldisc data * @data: byte received (may be invalid) * @flag: error received * * Handle an error in the receipt of data for a frame. Currently we just * go back to hunting for a SOF. * * FIXME: better diagnostics ? */ static void gsm_error(struct gsm_mux *gsm, unsigned char data, unsigned char flag) { gsm->state = GSM_SEARCH; gsm->io_error++; } /** * gsm_cleanup_mux - generic GSM protocol cleanup * @gsm: our mux * * Clean up the bits of the mux which are the same for all framing * protocols. Remove the mux from the mux table, stop all the timers * and then shut down each device hanging up the channels as we go. */ void gsm_cleanup_mux(struct gsm_mux *gsm) { int i; struct gsm_dlci *dlci = gsm->dlci[0]; struct gsm_msg *txq; gsm->dead = 1; spin_lock(&gsm_mux_lock); for (i = 0; i < MAX_MUX; i++) { if (gsm_mux[i] == gsm) { gsm_mux[i] = NULL; break; } } spin_unlock(&gsm_mux_lock); WARN_ON(i == MAX_MUX); del_timer_sync(&gsm->t2_timer); /* Now we are sure T2 has stopped */ if (dlci) { dlci->dead = 1; gsm_dlci_begin_close(dlci); wait_event_interruptible(gsm->event, dlci->state == DLCI_CLOSED); } /* Free up any link layer users */ for (i = 0; i < NUM_DLCI; i++) if (gsm->dlci[i]) gsm_dlci_free(gsm->dlci[i]); /* Now wipe the queues */ for (txq = gsm->tx_head; txq != NULL; txq = gsm->tx_head) { gsm->tx_head = txq->next; kfree(txq); } gsm->tx_tail = NULL; } EXPORT_SYMBOL_GPL(gsm_cleanup_mux); /** * gsm_activate_mux - generic GSM setup * @gsm: our mux * * Set up the bits of the mux which are the same for all framing * protocols. Add the mux to the mux table so it can be opened and * finally kick off connecting to DLCI 0 on the modem. */ int gsm_activate_mux(struct gsm_mux *gsm) { struct gsm_dlci *dlci; int i = 0; init_timer(&gsm->t2_timer); gsm->t2_timer.function = gsm_control_retransmit; gsm->t2_timer.data = (unsigned long)gsm; init_waitqueue_head(&gsm->event); spin_lock_init(&gsm->control_lock); spin_lock_init(&gsm->tx_lock); if (gsm->encoding == 0) gsm->receive = gsm0_receive; else gsm->receive = gsm1_receive; gsm->error = gsm_error; spin_lock(&gsm_mux_lock); for (i = 0; i < MAX_MUX; i++) { if (gsm_mux[i] == NULL) { gsm_mux[i] = gsm; break; } } spin_unlock(&gsm_mux_lock); if (i == MAX_MUX) return -EBUSY; dlci = gsm_dlci_alloc(gsm, 0); if (dlci == NULL) return -ENOMEM; gsm->dead = 0; /* Tty opens are now permissible */ return 0; } EXPORT_SYMBOL_GPL(gsm_activate_mux); /** * gsm_free_mux - free up a mux * @mux: mux to free * * Dispose of allocated resources for a dead mux. No refcounting * at present so the mux must be truly dead. */ void gsm_free_mux(struct gsm_mux *gsm) { kfree(gsm->txframe); kfree(gsm->buf); kfree(gsm); } EXPORT_SYMBOL_GPL(gsm_free_mux); /** * gsm_alloc_mux - allocate a mux * * Creates a new mux ready for activation. */ struct gsm_mux *gsm_alloc_mux(void) { struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL); if (gsm == NULL) return NULL; gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL); if (gsm->buf == NULL) { kfree(gsm); return NULL; } gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL); if (gsm->txframe == NULL) { kfree(gsm->buf); kfree(gsm); return NULL; } spin_lock_init(&gsm->lock); gsm->t1 = T1; gsm->t2 = T2; gsm->n2 = N2; gsm->ftype = UIH; gsm->initiator = 0; gsm->adaption = 1; gsm->encoding = 1; gsm->mru = 64; /* Default to encoding 1 so these should be 64 */ gsm->mtu = 64; gsm->dead = 1; /* Avoid early tty opens */ return gsm; } EXPORT_SYMBOL_GPL(gsm_alloc_mux); /** * gsmld_output - write to link * @gsm: our mux * @data: bytes to output * @len: size * * Write a block of data from the GSM mux to the data channel. This * will eventually be serialized from above but at the moment isn't. */ static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len) { if (tty_write_room(gsm->tty) < len) { set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags); return -ENOSPC; } if (debug & 4) { pr_debug("-->%d bytes out\n", len); hex_packet(data, len); } gsm->tty->ops->write(gsm->tty, data, len); return len; } /** * gsmld_attach_gsm - mode set up * @tty: our tty structure * @gsm: our mux * * Set up the MUX for basic mode and commence connecting to the * modem. Currently called from the line discipline set up but * will need moving to an ioctl path. */ static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm) { int ret; gsm->tty = tty_kref_get(tty); gsm->output = gsmld_output; ret = gsm_activate_mux(gsm); if (ret != 0) tty_kref_put(gsm->tty); return ret; } /** * gsmld_detach_gsm - stop doing 0710 mux * @tty: tty atttached to the mux * @gsm: mux * * Shutdown and then clean up the resources used by the line discipline */ static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm) { WARN_ON(tty != gsm->tty); gsm_cleanup_mux(gsm); tty_kref_put(gsm->tty); gsm->tty = NULL; } static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count) { struct gsm_mux *gsm = tty->disc_data; const unsigned char *dp; char *f; int i; char buf[64]; char flags; if (debug & 4) { pr_debug("Inbytes %dd\n", count); hex_packet(cp, count); } for (i = count, dp = cp, f = fp; i; i--, dp++) { flags = *f++; switch (flags) { case TTY_NORMAL: gsm->receive(gsm, *dp); break; case TTY_OVERRUN: case TTY_BREAK: case TTY_PARITY: case TTY_FRAME: gsm->error(gsm, *dp, flags); break; default: WARN_ONCE("%s: unknown flag %d\n", tty_name(tty, buf), flags); break; } } /* FASYNC if needed ? */ /* If clogged call tty_throttle(tty); */ } /** * gsmld_chars_in_buffer - report available bytes * @tty: tty device * * Report the number of characters buffered to be delivered to user * at this instant in time. * * Locking: gsm lock */ static ssize_t gsmld_chars_in_buffer(struct tty_struct *tty) { return 0; } /** * gsmld_flush_buffer - clean input queue * @tty: terminal device * * Flush the input buffer. Called when the line discipline is * being closed, when the tty layer wants the buffer flushed (eg * at hangup). */ static void gsmld_flush_buffer(struct tty_struct *tty) { } /** * gsmld_close - close the ldisc for this tty * @tty: device * * Called from the terminal layer when this line discipline is * being shut down, either because of a close or becsuse of a * discipline change. The function will not be called while other * ldisc methods are in progress. */ static void gsmld_close(struct tty_struct *tty) { struct gsm_mux *gsm = tty->disc_data; gsmld_detach_gsm(tty, gsm); gsmld_flush_buffer(tty); /* Do other clean up here */ gsm_free_mux(gsm); } /** * gsmld_open - open an ldisc * @tty: terminal to open * * Called when this line discipline is being attached to the * terminal device. Can sleep. Called serialized so that no * other events will occur in parallel. No further open will occur * until a close. */ static int gsmld_open(struct tty_struct *tty) { struct gsm_mux *gsm; if (tty->ops->write == NULL) return -EINVAL; /* Attach our ldisc data */ gsm = gsm_alloc_mux(); if (gsm == NULL) return -ENOMEM; tty->disc_data = gsm; tty->receive_room = 65536; /* Attach the initial passive connection */ gsm->encoding = 1; return gsmld_attach_gsm(tty, gsm); } /** * gsmld_write_wakeup - asynchronous I/O notifier * @tty: tty device * * Required for the ptys, serial driver etc. since processes * that attach themselves to the master and rely on ASYNC * IO must be woken up */ static void gsmld_write_wakeup(struct tty_struct *tty) { struct gsm_mux *gsm = tty->disc_data; unsigned long flags; /* Queue poll */ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); gsm_data_kick(gsm); if (gsm->tx_bytes < TX_THRESH_LO) { spin_lock_irqsave(&gsm->tx_lock, flags); gsm_dlci_data_sweep(gsm); spin_unlock_irqrestore(&gsm->tx_lock, flags); } } /** * gsmld_read - read function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer * @nr: size of I/O * * Perform reads for the line discipline. We are guaranteed that the * line discipline will not be closed under us but we may get multiple * parallel readers and must handle this ourselves. We may also get * a hangup. Always called in user context, may sleep. * * This code must be sure never to sleep through a hangup. */ static ssize_t gsmld_read(struct tty_struct *tty, struct file *file, unsigned char __user *buf, size_t nr) { return -EOPNOTSUPP; } /** * gsmld_write - write function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer * @nr: size of I/O * * Called when the owner of the device wants to send a frame * itself (or some other control data). The data is transferred * as-is and must be properly framed and checksummed as appropriate * by userspace. Frames are either sent whole or not at all as this * avoids pain user side. */ static ssize_t gsmld_write(struct tty_struct *tty, struct file *file, const unsigned char *buf, size_t nr) { int space = tty_write_room(tty); if (space >= nr) return tty->ops->write(tty, buf, nr); set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); return -ENOBUFS; } /** * gsmld_poll - poll method for N_GSM0710 * @tty: terminal device * @file: file accessing it * @wait: poll table * * Called when the line discipline is asked to poll() for data or * for special events. This code is not serialized with respect to * other events save open/close. * * This code must be sure never to sleep through a hangup. * Called without the kernel lock held - fine */ static unsigned int gsmld_poll(struct tty_struct *tty, struct file *file, poll_table *wait) { unsigned int mask = 0; struct gsm_mux *gsm = tty->disc_data; poll_wait(file, &tty->read_wait, wait); poll_wait(file, &tty->write_wait, wait); if (tty_hung_up_p(file)) mask |= POLLHUP; if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0) mask |= POLLOUT | POLLWRNORM; if (gsm->dead) mask |= POLLHUP; return mask; } static int gsmld_config(struct tty_struct *tty, struct gsm_mux *gsm, struct gsm_config *c) { int need_close = 0; int need_restart = 0; /* Stuff we don't support yet - UI or I frame transport, windowing */ if ((c->adaption != 1 && c->adaption != 2) || c->k) return -EOPNOTSUPP; /* Check the MRU/MTU range looks sane */ if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8) return -EINVAL; if (c->n2 < 3) return -EINVAL; if (c->encapsulation > 1) /* Basic, advanced, no I */ return -EINVAL; if (c->initiator > 1) return -EINVAL; if (c->i == 0 || c->i > 2) /* UIH and UI only */ return -EINVAL; /* * See what is needed for reconfiguration */ /* Timing fields */ if (c->t1 != 0 && c->t1 != gsm->t1) need_restart = 1; if (c->t2 != 0 && c->t2 != gsm->t2) need_restart = 1; if (c->encapsulation != gsm->encoding) need_restart = 1; if (c->adaption != gsm->adaption) need_restart = 1; /* Requires care */ if (c->initiator != gsm->initiator) need_close = 1; if (c->mru != gsm->mru) need_restart = 1; if (c->mtu != gsm->mtu) need_restart = 1; /* * Close down what is needed, restart and initiate the new * configuration */ if (need_close || need_restart) { gsm_dlci_begin_close(gsm->dlci[0]); /* This will timeout if the link is down due to N2 expiring */ wait_event_interruptible(gsm->event, gsm->dlci[0]->state == DLCI_CLOSED); if (signal_pending(current)) return -EINTR; } if (need_restart) gsm_cleanup_mux(gsm); gsm->initiator = c->initiator; gsm->mru = c->mru; gsm->mtu = c->mtu; gsm->encoding = c->encapsulation; gsm->adaption = c->adaption; gsm->n2 = c->n2; if (c->i == 1) gsm->ftype = UIH; else if (c->i == 2) gsm->ftype = UI; if (c->t1) gsm->t1 = c->t1; if (c->t2) gsm->t2 = c->t2; /* FIXME: We need to separate activation/deactivation from adding and removing from the mux array */ if (need_restart) gsm_activate_mux(gsm); if (gsm->initiator && need_close) gsm_dlci_begin_open(gsm->dlci[0]); return 0; } static int gsmld_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg) { struct gsm_config c; struct gsm_mux *gsm = tty->disc_data; switch (cmd) { case GSMIOC_GETCONF: memset(&c, 0, sizeof(c)); c.adaption = gsm->adaption; c.encapsulation = gsm->encoding; c.initiator = gsm->initiator; c.t1 = gsm->t1; c.t2 = gsm->t2; c.t3 = 0; /* Not supported */ c.n2 = gsm->n2; if (gsm->ftype == UIH) c.i = 1; else c.i = 2; pr_debug("Ftype %d i %d\n", gsm->ftype, c.i); c.mru = gsm->mru; c.mtu = gsm->mtu; c.k = 0; if (copy_to_user((void *)arg, &c, sizeof(c))) return -EFAULT; return 0; case GSMIOC_SETCONF: if (copy_from_user(&c, (void *)arg, sizeof(c))) return -EFAULT; return gsmld_config(tty, gsm, &c); default: return n_tty_ioctl_helper(tty, file, cmd, arg); } } /* Line discipline for real tty */ struct tty_ldisc_ops tty_ldisc_packet = { .owner = THIS_MODULE, .magic = TTY_LDISC_MAGIC, .name = "n_gsm", .open = gsmld_open, .close = gsmld_close, .flush_buffer = gsmld_flush_buffer, .chars_in_buffer = gsmld_chars_in_buffer, .read = gsmld_read, .write = gsmld_write, .ioctl = gsmld_ioctl, .poll = gsmld_poll, .receive_buf = gsmld_receive_buf, .write_wakeup = gsmld_write_wakeup }; /* * Virtual tty side */ #define TX_SIZE 512 static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk) { u8 modembits[5]; struct gsm_control *ctrl; int len = 2; if (brk) len++; modembits[0] = len << 1 | EA; /* Data bytes */ modembits[1] = dlci->addr << 2 | 3; /* DLCI, EA, 1 */ modembits[2] = gsm_encode_modem(dlci) << 1 | EA; if (brk) modembits[3] = brk << 4 | 2 | EA; /* Valid, EA */ ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1); if (ctrl == NULL) return -ENOMEM; return gsm_control_wait(dlci->gsm, ctrl); } static int gsm_carrier_raised(struct tty_port *port) { struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port); /* Not yet open so no carrier info */ if (dlci->state != DLCI_OPEN) return 0; if (debug & 2) return 1; return dlci->modem_rx & TIOCM_CD; } static void gsm_dtr_rts(struct tty_port *port, int onoff) { struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port); unsigned int modem_tx = dlci->modem_tx; if (onoff) modem_tx |= TIOCM_DTR | TIOCM_RTS; else modem_tx &= ~(TIOCM_DTR | TIOCM_RTS); if (modem_tx != dlci->modem_tx) { dlci->modem_tx = modem_tx; gsmtty_modem_update(dlci, 0); } } static const struct tty_port_operations gsm_port_ops = { .carrier_raised = gsm_carrier_raised, .dtr_rts = gsm_dtr_rts, }; static int gsmtty_open(struct tty_struct *tty, struct file *filp) { struct gsm_mux *gsm; struct gsm_dlci *dlci; struct tty_port *port; unsigned int line = tty->index; unsigned int mux = line >> 6; line = line & 0x3F; if (mux >= MAX_MUX) return -ENXIO; /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */ if (gsm_mux[mux] == NULL) return -EUNATCH; if (line == 0 || line > 61) /* 62/63 reserved */ return -ECHRNG; gsm = gsm_mux[mux]; if (gsm->dead) return -EL2HLT; dlci = gsm->dlci[line]; if (dlci == NULL) dlci = gsm_dlci_alloc(gsm, line); if (dlci == NULL) return -ENOMEM; port = &dlci->port; port->count++; tty->driver_data = dlci; tty_port_tty_set(port, tty); dlci->modem_rx = 0; /* We could in theory open and close before we wait - eg if we get a DM straight back. This is ok as that will have caused a hangup */ set_bit(ASYNCB_INITIALIZED, &port->flags); /* Start sending off SABM messages */ gsm_dlci_begin_open(dlci); /* And wait for virtual carrier */ return tty_port_block_til_ready(port, tty, filp); } static void gsmtty_close(struct tty_struct *tty, struct file *filp) { struct gsm_dlci *dlci = tty->driver_data; if (dlci == NULL) return; if (tty_port_close_start(&dlci->port, tty, filp) == 0) return; gsm_dlci_begin_close(dlci); tty_port_close_end(&dlci->port, tty); tty_port_tty_set(&dlci->port, NULL); } static void gsmtty_hangup(struct tty_struct *tty) { struct gsm_dlci *dlci = tty->driver_data; tty_port_hangup(&dlci->port); gsm_dlci_begin_close(dlci); } static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf, int len) { struct gsm_dlci *dlci = tty->driver_data; /* Stuff the bytes into the fifo queue */ int sent = kfifo_in_locked(dlci->fifo, buf, len, &dlci->lock); /* Need to kick the channel */ gsm_dlci_data_kick(dlci); return sent; } static int gsmtty_write_room(struct tty_struct *tty) { struct gsm_dlci *dlci = tty->driver_data; return TX_SIZE - kfifo_len(dlci->fifo); } static int gsmtty_chars_in_buffer(struct tty_str