// SPDX-License-Identifier: GPL-2.0 /* * n_gsm.c GSM 0710 tty multiplexor * Copyright (c) 2009/10 Intel Corporation * Copyright (c) 2022/23 Siemens Mobility GmbH * * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE * * * Outgoing path: * tty -> DLCI fifo -> scheduler -> GSM MUX data queue ---o-> ldisc * control message -> GSM MUX control queue --´ * * Incoming path: * ldisc -> gsm_queue() -o--> tty * `-> gsm_control_response() * * 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 ? * 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/signal.h> #include <linux/interrupt.h> #include <linux/tty.h> #include <linux/bitfield.h> #include <linux/ctype.h> #include <linux/mm.h> #include <linux/math.h> #include <linux/nospec.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 <net/arp.h> #include <linux/ip.h> #include <linux/netdevice.h> #include <linux/etherdevice.h> #include <linux/gsmmux.h> #include "tty.h" static int debug; module_param(debug, int, 0600); /* Module debug bits */ #define DBG_DUMP … #define DBG_CD_ON … #define DBG_DATA … #define DBG_ERRORS … #define DBG_TTY … #define DBG_PAYLOAD … /* Defaults: these are from the specification */ #define T1 … #define T2 … #define T3 … #define N2 … #define K … #define MAX_T3 … #define MAX_WINDOW_SIZE … /* Use long timers for testing at low speed with debug on */ #ifdef DEBUG_TIMING #define T1 … #define T2 … #endif /* * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte * limits so this is plenty */ #define MAX_MRU … #define MAX_MTU … #define MIN_MTU … /* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */ #define PROT_OVERHEAD … #define GSM_NET_TX_TIMEOUT … /* * struct gsm_mux_net - network interface * * Created when net interface is initialized. */ struct gsm_mux_net { … }; /* * 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 { … }; enum gsm_dlci_state { … }; enum gsm_dlci_mode { … }; /* * 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 { … }; /* * Parameter bits used for parameter negotiation according to 3GPP 27.010 * chapter 5.4.6.3.1. */ struct gsm_dlci_param_bits { … }; static_assert(…); #define PN_D_FIELD_DLCI … #define PN_I_CL_FIELD_FTYPE … #define PN_I_CL_FIELD_ADAPTION … #define PN_P_FIELD_PRIO … #define PN_T_FIELD_T1 … #define PN_N_FIELD_N1 … #define PN_NA_FIELD_N2 … #define PN_K_FIELD_K … /* Total number of supported devices */ #define GSM_TTY_MINORS … /* DLCI 0, 62/63 are special or reserved see gsmtty_open */ #define NUM_DLCI … /* * 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 { … }; enum gsm_encoding { … }; enum gsm_mux_state { … }; /* * 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 { … }; /* * Mux objects - needed so that we can translate a tty index into the * relevant mux and DLCI. */ #define MAX_MUX … static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */ static DEFINE_SPINLOCK(gsm_mux_lock); static struct tty_driver *gsm_tty_driver; /* * This section of the driver logic implements the GSM encodings * both the basic and the 'advanced'. Reliable transport is not * supported. */ #define CR … #define EA … #define PF … /* I is special: the rest are ..*/ #define RR … #define UI … #define RNR … #define REJ … #define DM … #define SABM … #define DISC … #define UA … #define UIH … /* Channel commands */ #define CMD_NSC … #define CMD_TEST … #define CMD_PSC … #define CMD_RLS … #define CMD_FCOFF … #define CMD_PN … #define CMD_RPN … #define CMD_FCON … #define CMD_CLD … #define CMD_SNC … #define CMD_MSC … /* Virtual modem bits */ #define MDM_FC … #define MDM_RTC … #define MDM_RTR … #define MDM_IC … #define MDM_DV … #define GSM0_SOF … #define GSM1_SOF … #define GSM1_ESCAPE … #define GSM1_ESCAPE_BITS … #define XON … #define XOFF … #define ISO_IEC_646_MASK … static const struct tty_port_operations gsm_port_ops; /* * CRC table for GSM 0710 */ static const u8 gsm_fcs8[256] = …; #define INIT_FCS … #define GOOD_FCS … static void gsm_dlci_close(struct gsm_dlci *dlci); static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len); static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk); static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len, u8 ctrl); static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg); static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr); static void gsmld_write_trigger(struct gsm_mux *gsm); static void gsmld_write_task(struct work_struct *work); /** * 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) { … } /** * 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) { … } /** * 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) { … } /** * gsm_read_ea_val - read a value until EA * @val: variable holding value * @data: buffer of data * @dlen: length of data * * Processes an EA value. Updates the passed variable and * returns the processed data length. */ static unsigned int gsm_read_ea_val(unsigned int *val, const u8 *data, int dlen) { … } /** * 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) { … } static void gsm_hex_dump_bytes(const char *fname, const u8 *data, unsigned long len) { … } /** * gsm_encode_params - encode DLCI parameters * @dlci: DLCI to encode from * @params: buffer to fill with the encoded parameters * * Encodes the parameters according to GSM 07.10 section 5.4.6.3.1 * table 3. */ static int gsm_encode_params(const struct gsm_dlci *dlci, struct gsm_dlci_param_bits *params) { … } /** * gsm_register_devices - register all tty devices for a given mux index * * @driver: the tty driver that describes the tty devices * @index: the mux number is used to calculate the minor numbers of the * ttys for this mux and may differ from the position in the * mux array. */ static int gsm_register_devices(struct tty_driver *driver, unsigned int index) { … } /** * gsm_unregister_devices - unregister all tty devices for a given mux index * * @driver: the tty driver that describes the tty devices * @index: the mux number is used to calculate the minor numbers of the * ttys for this mux and may differ from the position in the * mux array. */ static void gsm_unregister_devices(struct tty_driver *driver, unsigned int index) { … } /** * gsm_print_packet - display a frame for debug * @hdr: header to print before decode * @addr: address EA from the frame * @cr: C/R bit seen as initiator * @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) { … } /* * Link level transmission side */ /** * gsm_stuff_frame - bytestuff a packet * @input: input buffer * @output: output buffer * @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) { … } /** * gsm_send - send a control frame * @gsm: our GSM mux * @addr: address for control frame * @cr: command/response bit seen as initiator * @control: control byte including PF bit * * Format up and transmit a control frame. These should be transmitted * ahead of data when they are needed. */ static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control) { … } /** * gsm_dlci_clear_queues - remove outstanding data for a DLCI * @gsm: mux * @dlci: clear for this DLCI * * Clears the data queues for a given DLCI. */ static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci) { … } /** * 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_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) { … } /* Data transmission */ #define HDR_LEN … /** * 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) { … } /** * gsm_send_packet - sends a single packet * @gsm: GSM Mux * @msg: packet to send * * The given packet is encoded and sent out. No memory is freed. * The caller must hold the gsm tx lock. */ static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg) { … } /** * gsm_is_flow_ctrl_msg - checks if flow control message * @msg: message to check * * Returns true if the given message is a flow control command of the * control channel. False is returned in any other case. */ static bool gsm_is_flow_ctrl_msg(struct gsm_msg *msg) { … } /** * 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. * If we have been flow-stopped by a CMD_FCOFF, then we can only * send messages on DLCI0 until CMD_FCON. The caller must hold * the gsm tx lock. */ static int gsm_data_kick(struct gsm_mux *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. The Caller must hold * the gsm tx lock. */ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) { … } /** * 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) { … } /** * 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) { … } /** * 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) { … } /** * gsm_dlci_modem_output - try and push modem status out of a DLCI * @gsm: mux * @dlci: the DLCI to pull modem status from * @brk: break signal * * Push an empty frame in to the transmit queue to update the modem status * bits and to transmit an optional break. * * Caller must hold the tx_lock of the mux. */ static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci, u8 brk) { … } /** * 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 int gsm_dlci_data_sweep(struct gsm_mux *gsm) { … } /** * 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) { … } /* * Control message processing */ /** * gsm_control_command - send a command 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 command. */ static int gsm_control_command(struct gsm_mux *gsm, int cmd, const u8 *data, int dlen) { … } /** * 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, const u8 *data, int dlen) { … } /** * gsm_process_modem - process received modem status * @tty: virtual tty bound to the DLCI * @dlci: DLCI to affect * @modem: modem bits (full EA) * @slen: number of signal octets * * 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 slen) { … } /** * gsm_process_negotiation - process received parameters * @gsm: GSM channel * @addr: DLCI address * @cr: command/response * @params: encoded parameters from the parameter negotiation message * * Used when the response for our parameter negotiation command was * received. */ static int gsm_process_negotiation(struct gsm_mux *gsm, unsigned int addr, unsigned int cr, const struct gsm_dlci_param_bits *params) { … } /** * 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, const u8 *data, int clen) { … } /** * gsm_control_negotiation - parameter negotiation received * @gsm: GSM channel * @cr: command/response flag * @data: data following command * @dlen: data length * * We have received a parameter negotiation message. This is used by * the GSM mux protocol to configure protocol parameters for a new DLCI. */ static void gsm_control_negotiation(struct gsm_mux *gsm, unsigned int cr, const u8 *data, unsigned int dlen) { … } /** * 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, const u8 *data, int 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, const u8 *data, int clen) { … } /** * 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, const u8 *data, int clen) { … } /** * gsm_control_keep_alive - check timeout or start keep-alive * @t: timer contained in our gsm object * * Called off the keep-alive timer expiry signaling that our link * partner is not responding anymore. Link will be closed. * This is also called to startup our timer. */ static void gsm_control_keep_alive(struct timer_list *t) { … } /** * 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) { … } /** * gsm_control_retransmit - retransmit a control frame * @t: timer contained in 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(struct timer_list *t) { … } /** * 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) * @clen: 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) { … } /** * 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) { … } /* * 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) { … } /** * 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) { … } /** * gsm_dlci_negotiate - start parameter negotiation * @dlci: DLCI to open * * Starts the parameter negotiation for the new DLCI. This needs to be done * before the DLCI initialized the channel via SABM. */ static int gsm_dlci_negotiate(struct gsm_dlci *dlci) { … } /** * gsm_dlci_t1 - T1 timer expiry * @t: timer contained in the 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) * * Some control dlci can stay in ADM mode with other dlci working just * fine. In that case we can just keep the control dlci open after the * DLCI_OPENING retries time out. */ static void gsm_dlci_t1(struct timer_list *t) { … } /** * 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 or ADM, at which point * we will move into open state. Opening is done asynchronously with retry * running off timers and the responses. * Parameter negotiation is performed before SABM if required. */ static void gsm_dlci_begin_open(struct gsm_dlci *dlci) { … } /** * gsm_dlci_set_opening - change state to opening * @dlci: DLCI to open * * Change internal state to wait for DLCI open from initiator side. * We set off timers and responses upon reception of an SABM. */ static void gsm_dlci_set_opening(struct gsm_dlci *dlci) { … } /** * gsm_dlci_set_wait_config - wait for channel configuration * @dlci: DLCI to configure * * Wait for a DLCI configuration from the application. */ static void gsm_dlci_set_wait_config(struct gsm_dlci *dlci) { … } /** * 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) { … } /** * gsm_dlci_data - data arrived * @dlci: channel * @data: block of bytes received * @clen: 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, const u8 *data, int clen) { … } /** * gsm_dlci_command - 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, const u8 *data, int len) { … } /** * gsm_kick_timer - transmit if possible * @t: timer contained in our gsm object * * Transmit data from DLCIs 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_kick_timer(struct timer_list *t) { … } /** * gsm_dlci_copy_config_values - copy DLCI configuration * @dlci: source DLCI * @dc: configuration structure to fill */ static void gsm_dlci_copy_config_values(struct gsm_dlci *dlci, struct gsm_dlci_config *dc) { … } /** * gsm_dlci_config - configure DLCI from configuration * @dlci: DLCI to configure * @dc: DLCI configuration * @open: open DLCI after configuration? */ static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, int open) { … } /* * 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) { … } /** * gsm_dlci_free - free DLCI * @port: tty port for DLCI to free * * Free up a DLCI. * * Can sleep. */ static void gsm_dlci_free(struct tty_port *port) { … } static inline void dlci_get(struct gsm_dlci *dlci) { … } static inline void dlci_put(struct gsm_dlci *dlci) { … } static void gsm_destroy_network(struct gsm_dlci *dlci); /** * gsm_dlci_release - release DLCI * @dlci: DLCI to destroy * * Release a DLCI. Actual free is deferred until either * mux is closed or tty is closed - whichever is last. * * Can sleep. */ static void gsm_dlci_release(struct gsm_dlci *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) { … } /** * gsm0_receive_state_check_and_fix - check and correct receive state * @gsm: gsm data for this ldisc instance * * Ensures that the current receive state is valid for basic option mode. */ static void gsm0_receive_state_check_and_fix(struct gsm_mux *gsm) { … } /** * 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, u8 c) { … } /** * gsm1_receive_state_check_and_fix - check and correct receive state * @gsm: gsm data for this ldisc instance * * Ensures that the current receive state is valid for advanced option mode. */ static void gsm1_receive_state_check_and_fix(struct gsm_mux *gsm) { … } /** * 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, u8 c) { … } /** * gsm_error - handle tty error * @gsm: ldisc data * * 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) { … } /** * gsm_cleanup_mux - generic GSM protocol cleanup * @gsm: our mux * @disc: disconnect link? * * 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. */ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc) { … } /** * 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. */ static int gsm_activate_mux(struct gsm_mux *gsm) { … } /** * gsm_free_mux - free up a mux * @gsm: mux to free * * Dispose of allocated resources for a dead mux */ static void gsm_free_mux(struct gsm_mux *gsm) { … } /** * gsm_free_muxr - free up a mux * @ref: kreference to the mux to free * * Dispose of allocated resources for a dead mux */ static void gsm_free_muxr(struct kref *ref) { … } static inline void mux_get(struct gsm_mux *gsm) { … } static inline void mux_put(struct gsm_mux *gsm) { … } static inline unsigned int mux_num_to_base(struct gsm_mux *gsm) { … } static inline unsigned int mux_line_to_num(unsigned int line) { … } /** * gsm_alloc_mux - allocate a mux * * Creates a new mux ready for activation. */ static struct gsm_mux *gsm_alloc_mux(void) { … } static void gsm_copy_config_values(struct gsm_mux *gsm, struct gsm_config *c) { … } static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c) { … } static void gsm_copy_config_ext_values(struct gsm_mux *gsm, struct gsm_config_ext *ce) { … } static int gsm_config_ext(struct gsm_mux *gsm, struct gsm_config_ext *ce) { … } /** * 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) { … } /** * gsmld_write_trigger - schedule ldisc write task * @gsm: our mux */ static void gsmld_write_trigger(struct gsm_mux *gsm) { … } /** * gsmld_write_task - ldisc write task * @work: our tx write work * * Writes out data to the ldisc if possible. We are doing this here to * avoid dead-locking. This returns if no space or data is left for output. */ static void gsmld_write_task(struct work_struct *work) { … } /** * 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 void gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm) { … } /** * gsmld_detach_gsm - stop doing 0710 mux * @tty: tty attached 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) { … } static void gsmld_receive_buf(struct tty_struct *tty, const u8 *cp, const u8 *fp, size_t count) { … } /** * 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) { … } /** * 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) { … } /** * 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) { … } /** * gsmld_read - read function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer * @nr: size of I/O * @cookie: unused * @offset: unused * * 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, u8 *buf, size_t nr, void **cookie, unsigned long offset) { … } /** * 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 u8 *buf, size_t nr) { … } /** * 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 __poll_t gsmld_poll(struct tty_struct *tty, struct file *file, poll_table *wait) { … } static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) { … } /* * Network interface * */ static int gsm_mux_net_open(struct net_device *net) { … } static int gsm_mux_net_close(struct net_device *net) { … } static void dlci_net_free(struct gsm_dlci *dlci) { … } static void net_free(struct kref *ref) { … } static inline void muxnet_get(struct gsm_mux_net *mux_net) { … } static inline void muxnet_put(struct gsm_mux_net *mux_net) { … } static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb, struct net_device *net) { … } /* called when a packet did not ack after watchdogtimeout */ static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue) { … } static void gsm_mux_rx_netchar(struct gsm_dlci *dlci, const u8 *in_buf, int size) { … } static void gsm_mux_net_init(struct net_device *net) { … } /* caller holds the dlci mutex */ static void gsm_destroy_network(struct gsm_dlci *dlci) { … } /* caller holds the dlci mutex */ static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc) { … } /* Line discipline for real tty */ static struct tty_ldisc_ops tty_ldisc_packet = …; /* * Virtual tty side */ /** * gsm_modem_upd_via_data - send modem bits via convergence layer * @dlci: channel * @brk: break signal * * Send an empty frame to signal mobile state changes and to transmit the * break signal for adaption 2. */ static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk) { … } /** * gsm_modem_upd_via_msc - send modem bits via control frame * @dlci: channel * @brk: break signal */ static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk) { … } /** * gsm_modem_update - send modem status line state * @dlci: channel * @brk: break signal */ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk) { … } /** * gsm_wait_modem_change - wait for modem status line change * @dlci: channel * @mask: modem status line bits * * The function returns if: * - any given modem status line bit changed * - the wait event function got interrupted (e.g. by a signal) * - the underlying DLCI was closed * - the underlying ldisc device was removed */ static int gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask) { … } static bool gsm_carrier_raised(struct tty_port *port) { … } static void gsm_dtr_rts(struct tty_port *port, bool active) { … } static const struct tty_port_operations gsm_port_ops = …; static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty) { … } static int gsmtty_open(struct tty_struct *tty, struct file *filp) { … } static void gsmtty_close(struct tty_struct *tty, struct file *filp) { … } static void gsmtty_hangup(struct tty_struct *tty) { … } static ssize_t gsmtty_write(struct tty_struct *tty, const u8 *buf, size_t len) { … } static unsigned int gsmtty_write_room(struct tty_struct *tty) { … } static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty) { … } static void gsmtty_flush_buffer(struct tty_struct *tty) { … } static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout) { … } static int gsmtty_tiocmget(struct tty_struct *tty) { … } static int gsmtty_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear) { … } static int gsmtty_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) { … } static void gsmtty_set_termios(struct tty_struct *tty, const struct ktermios *old) { … } static void gsmtty_throttle(struct tty_struct *tty) { … } static void gsmtty_unthrottle(struct tty_struct *tty) { … } static int gsmtty_break_ctl(struct tty_struct *tty, int state) { … } static void gsmtty_cleanup(struct tty_struct *tty) { … } /* Virtual ttys for the demux */ static const struct tty_operations gsmtty_ops = …; static int __init gsm_init(void) { … } static void __exit gsm_exit(void) { … } module_init(…) …; module_exit(gsm_exit); MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS_LDISC(…);
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