diff options
Diffstat (limited to 'drivers/char/n_gsm.c')
| -rw-r--r-- | drivers/char/n_gsm.c | 2763 |
1 files changed, 2763 insertions, 0 deletions
diff --git a/drivers/char/n_gsm.c b/drivers/char/n_gsm.c new file mode 100644 index 00000000000..c4161d5e053 --- /dev/null +++ b/drivers/char/n_gsm.c @@ -0,0 +1,2763 @@ +/* + * 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 <linux/types.h> +#include <linux/major.h> +#include <linux/errno.h> +#include <linux/signal.h> +#include <linux/fcntl.h> +#include <linux/sched.h> +#include <linux/interrupt.h> +#include <linux/tty.h> +#include <linux/timer.h> +#include <linux/ctype.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/slab.h> +#include <linux/poll.h> +#include <linux/bitops.h> +#include <linux/file.h> +#include <linux/uaccess.h> +#include <linux/module.h> +#include <linux/timer.h> +#include <linux/tty_flip.h> +#include <linux/tty_driver.h> +#include <linux/serial.h> +#include <linux/kfifo.h> +#include <linux/skbuff.h> +#include <linux/gsmmux.h> + +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-arbitary 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 independant + * 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 + unsigned int len; + unsigned int address; + unsigned int count; + int escape; + int encoding; + u8 control; + u8 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; + + printk(KERN_INFO "%s %d) %c: ", hdr, addr, "RC"[cr]); + + switch (control & ~PF) { + case SABM: + printk(KERN_CONT "SABM"); + break; + case UA: + printk(KERN_CONT "UA"); + break; + case DISC: + printk(KERN_CONT "DISC"); + break; + case DM: + printk(KERN_CONT "DM"); + break; + case UI: + printk(KERN_CONT "UI"); + break; + case UIH: + printk(KERN_CONT "UIH"); + break; + default: + if (!(control & 0x01)) { + printk(KERN_CONT "I N(S)%d N(R)%d", + (control & 0x0E) >> 1, (control & 0xE)>> 5); + } else switch (control & 0x0F) { + case RR: + printk("RR(%d)", (control & 0xE0) >> 5); + break; + case RNR: + printk("RNR(%d)", (control & 0xE0) >> 5); + break; + case REJ: + printk("REJ(%d)", (control & 0xE0) >> 5); + break; + default: + printk(KERN_CONT "[%02X]", control); + } + } + + if (control & PF) + printk(KERN_CONT "(P)"); + else + printk(KERN_CONT "(F)"); + + if (dlen) { + int ct = 0; + while (dlen--) { + if (ct % 8 == 0) + printk(KERN_CONT "\n "); + printk(KERN_CONT "%02X ", *data++); + ct++; + } + } + printk(KERN_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) + printk("\n"); + printk("%02X ", *p++); + } + printk("\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) { + printk("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 >> 6) | EA; + *--dp = (msg->len & 127) << 1; + } + } + + *--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; + unsigned long flags; + + spin_lock_irqsave(&gsm->tx_lock, flags); + 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) + return; + /* DLCI empty - try the next */ + if (len == 0) + i++; + } + spin_unlock_irqrestore(&gsm->tx_lock, flags); +} + +/** + * 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); + 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 negotation */ + case CMD_SNC: /* Service negotation 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) +{</ |