--- /dev/null
+/*
+ * 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)
+{
+ 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|PF);
+ 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)
+ printk("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)
+ printk("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)
+ printk("%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);
+ if (gsm->fcs != GOOD_FCS) {
+ gsm->bad_fcs++;
+ if (debug & 4)
+ printk("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)
+{
+ 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; /* Address EA */
+ case GSM_ADDRESS:
+ 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_LEN;
+ break;
+ case GSM_LEN: /* 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;
+ 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->fcs = c;
+ gsm_queue(gsm);
+ /* And then back for the next frame */
+ gsm->state = GSM_SEARCH;
+ break;
+ }
+}
+
+/**
+ * gsm0_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 truely 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) {
+ printk("-->%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) {
+ printk("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:
+ printk(KERN_ERR "%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;
+
+ /* Queue poll */
+ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ gsm_data_kick(gsm);
+ if (gsm->tx_bytes < TX_THRESH_LO)
+ gsm_dlci_data_sweep(gsm);
+}
+
+/**
+ * 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->encoding = c->encapsulation;
+ gsm->adaption = c->adaption;
+
+ 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;
+ printk("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_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ return kfifo_len(dlci->fifo);
+}
+
+static void gsmtty_flush_buffer(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ /* Caution needed: If we implement reliable transport classes
+ then the data being transmitted can't simply be junked once
+ it has first hit the stack. Until then we can just blow it
+ away */
+ kfifo_reset(dlci->fifo);
+ /* Need to unhook this DLCI from the transmit queue logic */
+}
+
+static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
+{
+ /* The FIFO handles the queue so the kernel will do the right
+ thing waiting on chars_in_buffer before calling us. No work
+ to do here */
+}
+
+static int gsmtty_tiocmget(struct tty_struct *tty, struct file *filp)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ return dlci->modem_rx;
+}
+
+static int gsmtty_tiocmset(struct tty_struct *tty, struct file *filp,
+ unsigned int set, unsigned int clear)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ unsigned int modem_tx = dlci->modem_tx;
+
+ modem_tx &= clear;
+ modem_tx |= set;
+
+ if (modem_tx != dlci->modem_tx) {
+ dlci->modem_tx = modem_tx;
+ return gsmtty_modem_update(dlci, 0);
+ }
+ return 0;
+}
+
+
+static int gsmtty_ioctl(struct tty_struct *tty, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+ return -ENOIOCTLCMD;
+}
+
+static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
+{
+ /* For the moment its fixed. In actual fact the speed information
+ for the virtual channel can be propogated in both directions by
+ the RPN control message. This however rapidly gets nasty as we
+ then have to remap modem signals each way according to whether
+ our virtual cable is null modem etc .. */
+ tty_termios_copy_hw(tty->termios, old);
+}
+
+static void gsmtty_throttle(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (tty->termios->c_cflag & CRTSCTS)
+ dlci->modem_tx &= ~TIOCM_DTR;
+ dlci->throttled = 1;
+ /* Send an MSC with DTR cleared */
+ gsmtty_modem_update(dlci, 0);
+}
+
+static void gsmtty_unthrottle(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (tty->termios->c_cflag & CRTSCTS)
+ dlci->modem_tx |= TIOCM_DTR;
+ dlci->throttled = 0;
+ /* Send an MSC with DTR set */
+ gsmtty_modem_update(dlci, 0);
+}
+
+static int gsmtty_break_ctl(struct tty_struct *tty, int state)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ int encode = 0; /* Off */
+
+ if (state == -1) /* "On indefinitely" - we can't encode this
+ properly */
+ encode = 0x0F;
+ else if (state > 0) {
+ encode = state / 200; /* mS to encoding */
+ if (encode > 0x0F)
+ encode = 0x0F; /* Best effort */
+ }
+ return gsmtty_modem_update(dlci, encode);
+}
+
+static struct tty_driver *gsm_tty_driver;
+
+/* Virtual ttys for the demux */
+static const struct tty_operations gsmtty_ops = {
+ .open = gsmtty_open,
+ .close = gsmtty_close,
+ .write = gsmtty_write,
+ .write_room = gsmtty_write_room,
+ .chars_in_buffer = gsmtty_chars_in_buffer,
+ .flush_buffer = gsmtty_flush_buffer,
+ .ioctl = gsmtty_ioctl,
+ .throttle = gsmtty_throttle,
+ .unthrottle = gsmtty_unthrottle,
+ .set_termios = gsmtty_set_termios,
+ .hangup = gsmtty_hangup,
+ .wait_until_sent = gsmtty_wait_until_sent,
+ .tiocmget = gsmtty_tiocmget,
+ .tiocmset = gsmtty_tiocmset,
+ .break_ctl = gsmtty_break_ctl,
+};
+
+
+
+static int __init gsm_init(void)
+{
+ /* Fill in our line protocol discipline, and register it */
+ int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
+ if (status != 0) {
+ printk(KERN_ERR "n_gsm: can't register line discipline (err = %d)\n", status);
+ return status;
+ }
+
+ gsm_tty_driver = alloc_tty_driver(256);
+ if (!gsm_tty_driver) {
+ tty_unregister_ldisc(N_GSM0710);
+ printk(KERN_ERR "gsm_init: tty allocation failed.\n");
+ return -EINVAL;
+ }
+ gsm_tty_driver->owner = THIS_MODULE;
+ gsm_tty_driver->driver_name = "gsmtty";
+ gsm_tty_driver->name = "gsmtty";
+ gsm_tty_driver->major = 0; /* Dynamic */
+ gsm_tty_driver->minor_start = 0;
+ gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
+ gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
+ gsm_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
+ | TTY_DRIVER_HARDWARE_BREAK;
+ gsm_tty_driver->init_termios = tty_std_termios;
+ /* Fixme */
+ gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
+ tty_set_operations(gsm_tty_driver, &gsmtty_ops);
+
+ spin_lock_init(&gsm_mux_lock);
+
+ if (tty_register_driver(gsm_tty_driver)) {
+ put_tty_driver(gsm_tty_driver);
+ tty_unregister_ldisc(N_GSM0710);
+ printk(KERN_ERR "gsm_init: tty registration failed.\n");
+ return -EBUSY;
+ }
+ printk(KERN_INFO "gsm_init: loaded as %d,%d.\n", gsm_tty_driver->major, gsm_tty_driver->minor_start);
+ return 0;
+}
+
+static void __exit gsm_exit(void)
+{
+ int status = tty_unregister_ldisc(N_GSM0710);
+ if (status != 0)
+ printk(KERN_ERR "n_gsm: can't unregister line discipline (err = %d)\n", status);
+ tty_unregister_driver(gsm_tty_driver);
+ put_tty_driver(gsm_tty_driver);
+ printk(KERN_INFO "gsm_init: unloaded.\n");
+}
+
+module_init(gsm_init);
+module_exit(gsm_exit);
+
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_GSM0710);
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff