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-rw-r--r--drivers/tty/n_gsm.c3830
1 files changed, 3830 insertions, 0 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
new file mode 100644
index 000000000..6b6abce6b
--- /dev/null
+++ b/drivers/tty/n_gsm.c
@@ -0,0 +1,3830 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * n_gsm.c GSM 0710 tty multiplexor
+ * Copyright (c) 2009/10 Intel Corporation
+ *
+ * * 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 --ยด
+ *
+ * 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/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 <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 BIT(0) /* Data transmission dump. */
+#define DBG_CD_ON BIT(1) /* Always assume CD line on. */
+#define DBG_DATA BIT(2) /* Data transmission details. */
+#define DBG_ERRORS BIT(3) /* Details for fail conditions. */
+#define DBG_TTY BIT(4) /* Transmission statistics for DLCI TTYs. */
+#define DBG_PAYLOAD BIT(5) /* Limits DBG_DUMP to payload frames. */
+
+/* Defaults: these are from the specification */
+
+#define T1 10 /* 100mS */
+#define T2 34 /* 333mS */
+#define N2 3 /* Retry 3 times */
+
+/* Use long timers for testing at low speed with debug on */
+#ifdef DEBUG_TIMING
+#define T1 100
+#define T2 200
+#endif
+
+/*
+ * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
+ * limits so this is plenty
+ */
+#define MAX_MRU 1500
+#define MAX_MTU 1500
+/* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */
+#define PROT_OVERHEAD 7
+#define GSM_NET_TX_TIMEOUT (HZ*10)
+
+/*
+ * struct gsm_mux_net - network interface
+ *
+ * Created when net interface is initialized.
+ */
+struct gsm_mux_net {
+ struct kref ref;
+ struct gsm_dlci *dlci;
+};
+
+/*
+ * Each block of data we have queued to go out is in the form of
+ * a gsm_msg which holds everything we need in a link layer independent
+ * format
+ */
+
+struct gsm_msg {
+ struct list_head list;
+ 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[];
+};
+
+enum gsm_dlci_state {
+ DLCI_CLOSED,
+ DLCI_OPENING, /* Sending SABM not seen UA */
+ DLCI_OPEN, /* SABM/UA complete */
+ DLCI_CLOSING, /* Sending DISC not seen UA/DM */
+};
+
+enum gsm_dlci_mode {
+ DLCI_MODE_ABM, /* Normal Asynchronous Balanced Mode */
+ DLCI_MODE_ADM, /* Asynchronous Disconnected 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 {
+ struct gsm_mux *gsm;
+ int addr;
+ enum gsm_dlci_state state;
+ struct mutex mutex;
+
+ /* Link layer */
+ enum gsm_dlci_mode mode;
+ 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 */
+#define TX_SIZE 4096 /* Must be power of 2. */
+ struct kfifo fifo; /* Queue fifo for the DLCI */
+ int adaption; /* Adaption layer in use */
+ int prev_adaption;
+ u32 modem_rx; /* Our incoming virtual modem lines */
+ u32 modem_tx; /* Our outgoing modem lines */
+ bool dead; /* Refuse re-open */
+ /* Flow control */
+ bool throttled; /* Private copy of throttle state */
+ bool 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, const u8 *data, int len);
+ void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
+ struct net_device *net; /* network interface, if created */
+};
+
+/* Total number of supported devices */
+#define GSM_TTY_MINORS 256
+
+/* DLCI 0, 62/63 are special or reserved 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 */
+};
+
+enum gsm_encoding {
+ GSM_BASIC_OPT,
+ GSM_ADV_OPT,
+};
+
+enum gsm_mux_state {
+ GSM_SEARCH,
+ GSM_START,
+ GSM_ADDRESS,
+ GSM_CONTROL,
+ GSM_LEN,
+ GSM_DATA,
+ GSM_FCS,
+ GSM_OVERRUN,
+ GSM_LEN0,
+ GSM_LEN1,
+ GSM_SSOF,
+};
+
+/*
+ * 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;
+ struct mutex mutex;
+ unsigned int num;
+ struct kref ref;
+
+ /* Events on the GSM channel */
+ wait_queue_head_t event;
+
+ /* ldisc send work */
+ struct work_struct tx_work;
+
+ /* Bits for GSM mode decoding */
+
+ /* Framing Layer */
+ unsigned char *buf;
+ enum gsm_mux_state state;
+ unsigned int len;
+ unsigned int address;
+ unsigned int count;
+ bool escape;
+ enum gsm_encoding encoding;
+ u8 control;
+ u8 fcs;
+ u8 *txframe; /* TX framing buffer */
+
+ /* Method for the receiver side */
+ void (*receive)(struct gsm_mux *gsm, u8 ch);
+
+ /* Link Layer */
+ unsigned int mru;
+ unsigned int mtu;
+ int initiator; /* Did we initiate connection */
+ bool dead; /* Has the mux been shut down */
+ struct gsm_dlci *dlci[NUM_DLCI];
+ int old_c_iflag; /* termios c_iflag value before attach */
+ bool constipated; /* Asked by remote to shut up */
+ bool has_devices; /* Devices were registered */
+
+ spinlock_t tx_lock;
+ unsigned int tx_bytes; /* TX data outstanding */
+#define TX_THRESH_HI 8192
+#define TX_THRESH_LO 2048
+ struct list_head tx_ctrl_list; /* Pending control packets */
+ struct list_head tx_data_list; /* Pending data packets */
+
+ /* Control messages */
+ struct timer_list kick_timer; /* Kick TX queuing on timeout */
+ 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 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 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
+#define ISO_IEC_646_MASK 0x7F
+
+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
+
+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 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)
+{
+ 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_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)
+{
+ unsigned int len = 0;
+
+ for (; dlen > 0; dlen--) {
+ len++;
+ if (gsm_read_ea(val, *data++))
+ break;
+ }
+ return len;
+}
+
+/**
+ * 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 || dlci->gsm->initiator)
+ modembits |= MDM_DV;
+ return modembits;
+}
+
+static void gsm_hex_dump_bytes(const char *fname, const u8 *data,
+ unsigned long len)
+{
+ char *prefix;
+
+ if (!fname) {
+ print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, data, len,
+ true);
+ return;
+ }
+
+ prefix = kasprintf(GFP_ATOMIC, "%s: ", fname);
+ if (!prefix)
+ return;
+ print_hex_dump(KERN_INFO, prefix, DUMP_PREFIX_OFFSET, 16, 1, data, len,
+ true);
+ kfree(prefix);
+}
+
+/**
+ * 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)
+{
+ struct device *dev;
+ int i;
+ unsigned int base;
+
+ if (!driver || index >= MAX_MUX)
+ return -EINVAL;
+
+ base = index * NUM_DLCI; /* first minor for this index */
+ for (i = 1; i < NUM_DLCI; i++) {
+ /* Don't register device 0 - this is the control channel
+ * and not a usable tty interface
+ */
+ dev = tty_register_device(gsm_tty_driver, base + i, NULL);
+ if (IS_ERR(dev)) {
+ if (debug & DBG_ERRORS)
+ pr_info("%s failed to register device minor %u",
+ __func__, base + i);
+ for (i--; i >= 1; i--)
+ tty_unregister_device(gsm_tty_driver, base + i);
+ return PTR_ERR(dev);
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * 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)
+{
+ int i;
+ unsigned int base;
+
+ if (!driver || index >= MAX_MUX)
+ return;
+
+ base = index * NUM_DLCI; /* first minor for this index */
+ for (i = 1; i < NUM_DLCI; i++) {
+ /* Don't unregister device 0 - this is the control
+ * channel and not a usable tty interface
+ */
+ tty_unregister_device(gsm_tty_driver, base + i);
+ }
+}
+
+/**
+ * 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)
+{
+ if (!(debug & DBG_DUMP))
+ return;
+ /* Only show user payload frames if debug & DBG_PAYLOAD */
+ if (!(debug & DBG_PAYLOAD) && addr != 0)
+ if ((control & ~PF) == UI || (control & ~PF) == UIH)
+ return;
+
+ pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
+
+ switch (control & ~PF) {
+ case SABM:
+ pr_cont("SABM");
+ break;
+ case UA:
+ pr_cont("UA");
+ break;
+ case DISC:
+ pr_cont("DISC");
+ break;
+ case DM:
+ pr_cont("DM");
+ break;
+ case UI:
+ pr_cont("UI");
+ break;
+ case UIH:
+ pr_cont("UIH");
+ break;
+ default:
+ if (!(control & 0x01)) {
+ pr_cont("I N(S)%d N(R)%d",
+ (control & 0x0E) >> 1, (control & 0xE0) >> 5);
+ } else switch (control & 0x0F) {
+ case RR:
+ pr_cont("RR(%d)", (control & 0xE0) >> 5);
+ break;
+ case RNR:
+ pr_cont("RNR(%d)", (control & 0xE0) >> 5);
+ break;
+ case REJ:
+ pr_cont("REJ(%d)", (control & 0xE0) >> 5);
+ break;
+ default:
+ pr_cont("[%02X]", control);
+ }
+ }
+
+ if (control & PF)
+ pr_cont("(P)");
+ else
+ pr_cont("(F)");
+
+ gsm_hex_dump_bytes(NULL, data, 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)
+{
+ int olen = 0;
+ while (len--) {
+ if (*input == GSM1_SOF || *input == GSM1_ESCAPE
+ || (*input & ISO_IEC_646_MASK) == XON
+ || (*input & ISO_IEC_646_MASK) == XOFF) {
+ *output++ = GSM1_ESCAPE;
+ *output++ = *input++ ^ GSM1_ESCAPE_BITS;
+ olen++;
+ } else
+ *output++ = *input++;
+ olen++;
+ }
+ return olen;
+}
+
+/**
+ * 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)
+{
+ struct gsm_msg *msg;
+ u8 *dp;
+ int ocr;
+ unsigned long flags;
+
+ msg = gsm_data_alloc(gsm, addr, 0, control);
+ if (!msg)
+ return -ENOMEM;
+
+ /* toggle C/R coding if not initiator */
+ ocr = cr ^ (gsm->initiator ? 0 : 1);
+
+ msg->data -= 3;
+ dp = msg->data;
+ *dp++ = (addr << 2) | (ocr << 1) | EA;
+ *dp++ = control;
+
+ if (gsm->encoding == GSM_BASIC_OPT)
+ *dp++ = EA; /* Length of data = 0 */
+
+ *dp = 0xFF - gsm_fcs_add_block(INIT_FCS, msg->data, dp - msg->data);
+ msg->len = (dp - msg->data) + 1;
+
+ gsm_print_packet("Q->", addr, cr, control, NULL, 0);
+
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ list_add_tail(&msg->list, &gsm->tx_ctrl_list);
+ gsm->tx_bytes += msg->len;
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
+
+ return 0;
+}
+
+/**
+ * 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)
+{
+ struct gsm_msg *msg, *nmsg;
+ int addr = dlci->addr;
+ unsigned long flags;
+
+ /* Clear DLCI write fifo first */
+ spin_lock_irqsave(&dlci->lock, flags);
+ kfifo_reset(&dlci->fifo);
+ spin_unlock_irqrestore(&dlci->lock, flags);
+
+ /* Clear data packets in MUX write queue */
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
+ if (msg->addr != addr)
+ continue;
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ }
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+}
+
+/**
+ * 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;
+ INIT_LIST_HEAD(&m->list);
+ return m;
+}
+
+/**
+ * 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)
+{
+ int len, ret;
+
+
+ if (gsm->encoding == GSM_BASIC_OPT) {
+ gsm->txframe[0] = GSM0_SOF;
+ memcpy(gsm->txframe + 1, msg->data, msg->len);
+ gsm->txframe[msg->len + 1] = GSM0_SOF;
+ len = msg->len + 2;
+ } else {
+ gsm->txframe[0] = GSM1_SOF;
+ len = gsm_stuff_frame(msg->data, gsm->txframe + 1, msg->len);
+ gsm->txframe[len + 1] = GSM1_SOF;
+ len += 2;
+ }
+
+ if (debug & DBG_DATA)
+ gsm_hex_dump_bytes(__func__, gsm->txframe, len);
+ gsm_print_packet("-->", msg->addr, gsm->initiator, msg->ctrl, msg->data,
+ msg->len);
+
+ ret = gsmld_output(gsm, gsm->txframe, len);
+ if (ret <= 0)
+ return ret;
+ /* FIXME: Can eliminate one SOF in many more cases */
+ gsm->tx_bytes -= msg->len;
+
+ return 0;
+}
+
+/**
+ * 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)
+{
+ unsigned int cmd;
+
+ if (msg->addr > 0)
+ return false;
+
+ switch (msg->ctrl & ~PF) {
+ case UI:
+ case UIH:
+ cmd = 0;
+ if (gsm_read_ea_val(&cmd, msg->data + 2, msg->len - 2) < 1)
+ break;
+ switch (cmd & ~PF) {
+ case CMD_FCOFF:
+ case CMD_FCON:
+ return true;
+ }
+ break;
+ }
+
+ return false;
+}
+
+/**
+ * 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)
+{
+ struct gsm_msg *msg, *nmsg;
+ struct gsm_dlci *dlci;
+ int ret;
+
+ clear_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
+
+ /* Serialize control messages and control channel messages first */
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_ctrl_list, list) {
+ if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg))
+ continue;
+ ret = gsm_send_packet(gsm, msg);
+ switch (ret) {
+ case -ENOSPC:
+ return -ENOSPC;
+ case -ENODEV:
+ /* ldisc not open */
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ default:
+ if (ret >= 0) {
+ list_del(&msg->list);
+ kfree(msg);
+ }
+ break;
+ }
+ }
+
+ if (gsm->constipated)
+ return -EAGAIN;
+
+ /* Serialize other channels */
+ if (list_empty(&gsm->tx_data_list))
+ return 0;
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
+ dlci = gsm->dlci[msg->addr];
+ /* Send only messages for DLCIs with valid state */
+ if (dlci->state != DLCI_OPEN) {
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ }
+ ret = gsm_send_packet(gsm, msg);
+ switch (ret) {
+ case -ENOSPC:
+ return -ENOSPC;
+ case -ENODEV:
+ /* ldisc not open */
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ default:
+ if (ret >= 0) {
+ list_del(&msg->list);
+ kfree(msg);
+ }
+ break;
+ }
+ }
+
+ return 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 == GSM_BASIC_OPT) {
+ if (msg->len < 128)
+ *--dp = (msg->len << 1) | EA;
+ else {
+ *--dp = (msg->len >> 7); /* bits 7 - 15 */
+ *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
+ }
+ }
+
+ *--dp = msg->ctrl;
+ if (gsm->initiator)
+ *--dp = (msg->addr << 2) | CR | 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 */
+ switch (msg->ctrl & ~PF) {
+ case UI:
+ case UIH:
+ if (msg->addr > 0) {
+ list_add_tail(&msg->list, &gsm->tx_data_list);
+ break;
+ }
+ fallthrough;
+ default:
+ list_add_tail(&msg->list, &gsm->tx_ctrl_list);
+ break;
+ }
+ gsm->tx_bytes += msg->len;
+
+ gsmld_write_trigger(gsm);
+ mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
+}
+
+/**
+ * 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 h, len, size;
+
+ /* for modem bits without break data */
+ h = ((dlci->adaption == 1) ? 0 : 1);
+
+ len = kfifo_len(&dlci->fifo);
+ if (len == 0)
+ return 0;
+
+ /* MTU/MRU count only the data bits but watch adaption mode */
+ if ((len + h) > gsm->mtu)
+ len = gsm->mtu - h;
+
+ size = len + h;
+
+ msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
+ if (!msg)
+ return -ENOMEM;
+ dp = msg->data;
+ switch (dlci->adaption) {
+ case 1: /* Unstructured */
+ break;
+ case 2: /* Unstructured with modem bits.
+ * Always one byte as we never send inline break data
+ */
+ *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
+ break;
+ default:
+ pr_err("%s: unsupported adaption %d\n", __func__,
+ dlci->adaption);
+ break;
+ }
+
+ WARN_ON(len != kfifo_out_locked(&dlci->fifo, dp, len,
+ &dlci->lock));
+
+ /* Notify upper layer about available send space. */
+ tty_port_tty_wakeup(&dlci->port);
+
+ __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_tail(&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 */
+ dev_kfree_skb_any(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);
+ if (msg == NULL) {
+ skb_queue_tail(&dlci->skb_list, dlci->skb);
+ dlci->skb = 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, dlci->skb->data, len);
+ skb_pull(dlci->skb, len);
+ __gsm_data_queue(dlci, msg);
+ if (last) {
+ dev_kfree_skb_any(dlci->skb);
+ dlci->skb = NULL;
+ }
+ return size;
+}
+
+/**
+ * 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)
+{
+ u8 *dp = NULL;
+ struct gsm_msg *msg;
+ int size = 0;
+
+ /* for modem bits without break data */
+ switch (dlci->adaption) {
+ case 1: /* Unstructured */
+ break;
+ case 2: /* Unstructured with modem bits. */
+ size++;
+ if (brk > 0)
+ size++;
+ break;
+ default:
+ pr_err("%s: unsupported adaption %d\n", __func__,
+ dlci->adaption);
+ return -EINVAL;
+ }
+
+ msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
+ if (!msg) {
+ pr_err("%s: gsm_data_alloc error", __func__);
+ return -ENOMEM;
+ }
+ dp = msg->data;
+ switch (dlci->adaption) {
+ case 1: /* Unstructured */
+ break;
+ case 2: /* Unstructured with modem bits. */
+ if (brk == 0) {
+ *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
+ } else {
+ *dp++ = gsm_encode_modem(dlci) << 1;
+ *dp++ = (brk << 4) | 2 | EA; /* Length, Break, EA */
+ }
+ break;
+ default:
+ /* Handled above */
+ break;
+ }
+
+ __gsm_data_queue(dlci, msg);
+ 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 int gsm_dlci_data_sweep(struct gsm_mux *gsm)
+{
+ /* Priority ordering: We should do priority with RR of the groups */
+ int i, len, ret = 0;
+ bool sent;
+ struct gsm_dlci *dlci;
+
+ while (gsm->tx_bytes < TX_THRESH_HI) {
+ for (sent = false, i = 1; i < NUM_DLCI; i++) {
+ dlci = gsm->dlci[i];
+ /* skip unused or blocked channel */
+ if (!dlci || dlci->constipated)
+ continue;
+ /* skip channels with invalid state */
+ if (dlci->state != DLCI_OPEN)
+ continue;
+ /* count the sent data per adaption */
+ if (dlci->adaption < 3 && !dlci->net)
+ len = gsm_dlci_data_output(gsm, dlci);
+ else
+ len = gsm_dlci_data_output_framed(gsm, dlci);
+ /* on error exit */
+ if (len < 0)
+ return ret;
+ if (len > 0) {
+ ret++;
+ sent = true;
+ /* The lower DLCs can starve the higher DLCs! */
+ break;
+ }
+ /* try next */
+ }
+ if (!sent)
+ break;
+ };
+
+ return ret;
+}
+
+/**
+ * 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;
+ int sweep;
+
+ if (dlci->constipated)
+ return;
+
+ spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
+ /* If we have nothing running then we need to fire up */
+ sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
+ if (dlci->gsm->tx_bytes == 0) {
+ if (dlci->net)
+ gsm_dlci_data_output_framed(dlci->gsm, dlci);
+ else
+ gsm_dlci_data_output(dlci->gsm, dlci);
+ }
+ if (sweep)
+ gsm_dlci_data_sweep(dlci->gsm);
+ spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
+}
+
+/*
+ * 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)
+{
+ struct gsm_msg *msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
+
+ if (msg == NULL)
+ return -ENOMEM;
+
+ msg->data[0] = (cmd << 1) | CR | EA; /* Set C/R */
+ msg->data[1] = (dlen << 1) | EA;
+ memcpy(msg->data + 2, data, dlen);
+ gsm_data_queue(gsm->dlci[0], msg);
+
+ return 0;
+}
+
+/**
+ * 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)
+{
+ struct gsm_msg *msg;
+ msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
+ if (msg == NULL)
+ return;
+ msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
+ msg->data[1] = (dlen << 1) | EA;
+ memcpy(msg->data + 2, data, dlen);
+ gsm_data_queue(gsm->dlci[0], msg);
+}
+
+/**
+ * gsm_process_modem - process received modem status
+ * @tty: virtual tty bound to the DLCI
+ * @dlci: DLCI to affect
+ * @modem: modem bits (full EA)
+ * @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)
+{
+ int mlines = 0;
+ u8 brk = 0;
+ int fc;
+
+ /* The modem status command can either contain one octet (V.24 signals)
+ * or two octets (V.24 signals + break signals). This is specified in
+ * section 5.4.6.3.7 of the 07.10 mux spec.
+ */
+
+ if (slen == 1)
+ modem = modem & 0x7f;
+ else {
+ brk = modem & 0x7f;
+ modem = (modem >> 7) & 0x7f;
+ }
+
+ /* Flow control/ready to communicate */
+ fc = (modem & MDM_FC) || !(modem & MDM_RTR);
+ if (fc && !dlci->constipated) {
+ /* Need to throttle our output on this device */
+ dlci->constipated = true;
+ } else if (!fc && dlci->constipated) {
+ dlci->constipated = false;
+ gsm_dlci_data_kick(dlci);
+ }
+
+ /* Map modem bits */
+ if (modem & MDM_RTC)
+ mlines |= TIOCM_DSR | TIOCM_DTR;
+ 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 (!C_CLOCAL(tty))
+ tty_hangup(tty);
+ }
+ if (brk & 0x01)
+ tty_insert_flip_char(&dlci->port, 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, const u8 *data, int clen)
+{
+ unsigned int addr = 0;
+ unsigned int modem = 0;
+ struct gsm_dlci *dlci;
+ int len = clen;
+ int cl = clen;
+ const u8 *dp = data;
+ struct tty_struct *tty;
+
+ len = gsm_read_ea_val(&addr, data, cl);
+ if (len < 1)
+ return;
+
+ addr >>= 1;
+ /* Closed port, or invalid ? */
+ if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
+ return;
+ dlci = gsm->dlci[addr];
+
+ /* Must be at least one byte following the EA */
+ if ((cl - len) < 1)
+ return;
+
+ dp += len;
+ cl -= len;
+
+ /* get the modem status */
+ len = gsm_read_ea_val(&modem, dp, cl);
+ if (len < 1)
+ return;
+
+ tty = tty_port_tty_get(&dlci->port);
+ gsm_process_modem(tty, dlci, modem, cl);
+ 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, const u8 *data, int clen)
+{
+ struct tty_port *port;
+ unsigned int addr = 0;
+ u8 bits;
+ int len = clen;
+ const 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;
+
+ port = &gsm->dlci[addr]->port;
+
+ if (bits & 2)
+ tty_insert_flip_char(port, 0, TTY_OVERRUN);
+ if (bits & 4)
+ tty_insert_flip_char(port, 0, TTY_PARITY);
+ if (bits & 8)
+ tty_insert_flip_char(port, 0, TTY_FRAME);
+
+ tty_flip_buffer_push(port);
+
+ 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,
+ const 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 = true;
+ gsm->dead = true;
+ 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 can accept data again */
+ gsm->constipated = false;
+ gsm_control_reply(gsm, CMD_FCON, NULL, 0);
+ /* Kick the link in case it is idling */
+ gsmld_write_trigger(gsm);
+ break;
+ case CMD_FCOFF:
+ /* Modem wants us to STFU */
+ gsm->constipated = true;
+ gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
+ break;
+ case CMD_MSC:
+ /* Out of band modem line change indicator for a DLCI */
+ gsm_control_modem(gsm, data, clen);
+ break;
+ case CMD_RLS:
+ /* Out of band error reception for a DLCI */
+ gsm_control_rls(gsm, data, clen);
+ break;
+ case CMD_PSC:
+ /* Modem wishes to enter power saving state */
+ gsm_control_reply(gsm, CMD_PSC, NULL, 0);
+ break;
+ /* Optional unsupported commands */
+ case CMD_PN: /* Parameter negotiation */
+ case CMD_RPN: /* Remote port negotiation */
+ case CMD_SNC: /* Service negotiation command */
+ default:
+ /* Reply to bad commands with an NSC */
+ buf[0] = command;
+ gsm_control_reply(gsm, CMD_NSC, buf, 1);
+ break;
+ }
+}
+
+/**
+ * gsm_control_response - process a response to our control
+ * @gsm: our GSM mux
+ * @command: the command (response) EA
+ * @data: data beyond the command/length EA
+ * @clen: length
+ *
+ * Process a response to an outstanding command. We only allow a single
+ * control message in flight so this is fairly easy. All the clean up
+ * is done by the caller, we just update the fields, flag it as done
+ * and return
+ */
+
+static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
+ const 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)
+{
+ gsm_control_command(gsm, ctrl->cmd, ctrl->data, ctrl->len);
+}
+
+/**
+ * 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)
+{
+ struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
+ struct gsm_control *ctrl;
+ unsigned long flags;
+ spin_lock_irqsave(&gsm->control_lock, flags);
+ ctrl = gsm->pending_cmd;
+ if (ctrl) {
+ if (gsm->cretries == 0 || !gsm->dlci[0] || gsm->dlci[0]->dead) {
+ gsm->pending_cmd = NULL;
+ ctrl->error = -ETIMEDOUT;
+ ctrl->done = 1;
+ spin_unlock_irqrestore(&gsm->control_lock, flags);
+ wake_up(&gsm->event);
+ return;
+ }
+ gsm->cretries--;
+ 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)
+ * @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)
+{
+ struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
+ GFP_ATOMIC);
+ 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;
+
+ /* If DLCI0 is in ADM mode skip retries, it won't respond */
+ if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
+ gsm->cretries = 0;
+ else
+ 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 & DBG_ERRORS)
+ pr_debug("DLCI %d goes closed.\n", dlci->addr);
+ dlci->state = DLCI_CLOSED;
+ /* Prevent us from sending data before the link is up again */
+ dlci->constipated = true;
+ if (dlci->addr != 0) {
+ tty_port_tty_hangup(&dlci->port, false);
+ gsm_dlci_clear_queues(dlci->gsm, dlci);
+ /* Ensure that gsmtty_open() can return. */
+ tty_port_set_initialized(&dlci->port, 0);
+ wake_up_interruptible(&dlci->port.open_wait);
+ } else
+ dlci->gsm->dead = true;
+ /* A DLCI 0 close is a MUX termination so we need to kick that
+ back to userspace somehow */
+ gsm_dlci_data_kick(dlci);
+ wake_up(&dlci->gsm->event);
+}
+
+/**
+ * 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;
+ dlci->constipated = false;
+ if (debug & DBG_ERRORS)
+ pr_debug("DLCI %d goes open.\n", dlci->addr);
+ /* Send current modem state */
+ if (dlci->addr)
+ gsm_modem_update(dlci, 0);
+ gsm_dlci_data_kick(dlci);
+ wake_up(&dlci->gsm->event);
+}
+
+/**
+ * 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)
+{
+ struct gsm_dlci *dlci = from_timer(dlci, t, t1);
+ struct gsm_mux *gsm = dlci->gsm;
+
+ switch (dlci->state) {
+ case DLCI_OPENING:
+ if (dlci->retries) {
+ dlci->retries--;
+ gsm_command(dlci->gsm, dlci->addr, SABM|PF);
+ mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
+ } else if (!dlci->addr && gsm->control == (DM | PF)) {
+ if (debug & DBG_ERRORS)
+ pr_info("DLCI %d opening in ADM mode.\n",
+ dlci->addr);
+ dlci->mode = DLCI_MODE_ADM;
+ gsm_dlci_open(dlci);
+ } else {
+ gsm_dlci_begin_close(dlci); /* prevent half open link */
+ }
+
+ break;
+ case DLCI_CLOSING:
+ if (dlci->retries) {
+ 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;
+ default:
+ pr_debug("%s: unhandled state: %d\n", __func__, dlci->state);
+ 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 or ADM, 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_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)
+{
+ switch (dlci->state) {
+ case DLCI_CLOSED:
+ case DLCI_CLOSING:
+ dlci->state = DLCI_OPENING;
+ break;
+ default:
+ break;
+ }
+}
+
+/**
+ * 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
+ * @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)
+{
+ /* krefs .. */
+ struct tty_port *port = &dlci->port;
+ struct tty_struct *tty;
+ unsigned int modem = 0;
+ int len;
+
+ if (debug & DBG_TTY)
+ pr_debug("%d bytes for tty\n", clen);
+ switch (dlci->adaption) {
+ /* Unsupported types */
+ case 4: /* Packetised interruptible data */
+ break;
+ case 3: /* Packetised uininterruptible voice/data */
+ break;
+ case 2: /* Asynchronous serial with line state in each frame */
+ len = gsm_read_ea_val(&modem, data, clen);
+ if (len < 1)
+ return;
+ tty = tty_port_tty_get(port);
+ if (tty) {
+ gsm_process_modem(tty, dlci, modem, len);
+ tty_wakeup(tty);
+ tty_kref_put(tty);
+ }
+ /* Skip processed modem data */
+ data += len;
+ clen -= len;
+ fallthrough;
+ case 1: /* Line state will go via DLCI 0 controls only */
+ default:
+ tty_insert_flip_string(port, data, clen);
+ tty_flip_buffer_push(port);
+ }
+}
+
+/**
+ * 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)
+{
+ /* See what command is involved */
+ unsigned int command = 0;
+ unsigned int clen = 0;
+ unsigned int dlen;
+
+ /* read the command */
+ dlen = gsm_read_ea_val(&command, data, len);
+ len -= dlen;
+ data += dlen;
+
+ /* read any control data */
+ dlen = gsm_read_ea_val(&clen, data, len);
+ len -= dlen;
+ data += dlen;
+
+ /* 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);
+}
+
+/**
+ * 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)
+{
+ struct gsm_mux *gsm = from_timer(gsm, t, kick_timer);
+ unsigned long flags;
+ int sent = 0;
+
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ /* If we have nothing running then we need to fire up */
+ if (gsm->tx_bytes < TX_THRESH_LO)
+ sent = gsm_dlci_data_sweep(gsm);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+ if (sent && debug & DBG_DATA)
+ pr_info("%s TX queue stalled\n", __func__);
+}
+
+/*
+ * 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);
+ mutex_init(&dlci->mutex);
+ if (kfifo_alloc(&dlci->fifo, TX_SIZE, GFP_KERNEL) < 0) {
+ kfree(dlci);
+ return NULL;
+ }
+
+ skb_queue_head_init(&dlci->skb_list);
+ timer_setup(&dlci->t1, gsm_dlci_t1, 0);
+ 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;
+ /* Prevent us from sending data before the link is up */
+ dlci->constipated = true;
+ } else {
+ dlci->data = gsm_dlci_command;
+ }
+ gsm->dlci[addr] = dlci;
+ return dlci;
+}
+
+/**
+ * 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)
+{
+ struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
+
+ del_timer_sync(&dlci->t1);
+ dlci->gsm->dlci[dlci->addr] = NULL;
+ kfifo_free(&dlci->fifo);
+ while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
+ dev_kfree_skb(dlci->skb);
+ kfree(dlci);
+}
+
+static inline void dlci_get(struct gsm_dlci *dlci)
+{
+ tty_port_get(&dlci->port);
+}
+
+static inline void dlci_put(struct gsm_dlci *dlci)
+{
+ tty_port_put(&dlci->port);
+}
+
+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)
+{
+ struct tty_struct *tty = tty_port_tty_get(&dlci->port);
+ if (tty) {
+ mutex_lock(&dlci->mutex);
+ gsm_destroy_network(dlci);
+ mutex_unlock(&dlci->mutex);
+
+ /* We cannot use tty_hangup() because in tty_kref_put() the tty
+ * driver assumes that the hangup queue is free and reuses it to
+ * queue release_one_tty() -> NULL pointer panic in
+ * process_one_work().
+ */
+ tty_vhangup(tty);
+
+ tty_port_tty_set(&dlci->port, NULL);
+ tty_kref_put(tty);
+ }
+ dlci->state = DLCI_CLOSED;
+ dlci_put(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;
+
+ if (gsm->fcs != GOOD_FCS) {
+ gsm->bad_fcs++;
+ if (debug & DBG_DATA)
+ pr_debug("BAD FCS %02x\n", gsm->fcs);
+ return;
+ }
+ address = gsm->address >> 1;
+ if (address >= NUM_DLCI)
+ goto invalid;
+
+ cr = gsm->address & 1; /* C/R bit */
+ cr ^= gsm->initiator ? 0 : 1; /* Flip so 1 always means command */
+
+ gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
+
+ dlci = gsm->dlci[address];
+
+ switch (gsm->control) {
+ case SABM|PF:
+ if (cr == 1)
+ goto invalid;
+ if (dlci == NULL)
+ dlci = gsm_dlci_alloc(gsm, address);
+ if (dlci == NULL)
+ return;
+ if (dlci->dead)
+ gsm_response(gsm, address, DM|PF);
+ else {
+ gsm_response(gsm, address, UA|PF);
+ gsm_dlci_open(dlci);
+ }
+ break;
+ case DISC|PF:
+ if (cr == 1)
+ goto invalid;
+ if (dlci == NULL || dlci->state == DLCI_CLOSED) {
+ gsm_response(gsm, address, DM|PF);
+ return;
+ }
+ /* Real close complete */
+ gsm_response(gsm, address, UA|PF);
+ gsm_dlci_close(dlci);
+ break;
+ 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;
+ default:
+ pr_debug("%s: unhandled state: %d\n", __func__,
+ dlci->state);
+ 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 (dlci == NULL || dlci->state != DLCI_OPEN) {
+ gsm_response(gsm, address, DM|PF);
+ return;
+ }
+ dlci->data(dlci, gsm->buf, gsm->len);
+ break;
+ default:
+ goto invalid;
+ }
+ return;
+invalid:
+ gsm->malformed++;
+ return;
+}
+
+
+/**
+ * gsm0_receive - perform processing for non-transparency
+ * @gsm: gsm data for this ldisc instance
+ * @c: character
+ *
+ * Receive bytes in gsm mode 0
+ */
+
+static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
+{
+ unsigned int len;
+
+ switch (gsm->state) {
+ case GSM_SEARCH: /* SOF marker */
+ if (c == GSM0_SOF) {
+ gsm->state = GSM_ADDRESS;
+ gsm->address = 0;
+ gsm->len = 0;
+ gsm->fcs = INIT_FCS;
+ }
+ break;
+ case GSM_ADDRESS: /* Address EA */
+ gsm->fcs = gsm_fcs_add(gsm->fcs, c);
+ if (gsm_read_ea(&gsm->address, c))
+ gsm->state = GSM_CONTROL;
+ break;
+ case GSM_CONTROL: /* Control Byte */
+ gsm->fcs = gsm_fcs_add(gsm->fcs, c);
+ gsm->control = c;
+ gsm->state = GSM_LEN0;
+ break;
+ case GSM_LEN0: /* Length EA */
+ gsm->fcs = gsm_fcs_add(gsm->fcs, c);
+ if (gsm_read_ea(&gsm->len, c)) {
+ if (gsm->len > gsm->mru) {
+ gsm->bad_size++;
+ gsm->state = GSM_SEARCH;
+ break;
+ }
+ gsm->count = 0;
+ if (!gsm->len)
+ gsm->state = GSM_FCS;
+ else
+ gsm->state = GSM_DATA;
+ break;
+ }
+ gsm->state = GSM_LEN1;
+ break;
+ case GSM_LEN1:
+ gsm->fcs = gsm_fcs_add(gsm->fcs, c);
+ len = c;
+ gsm->len |= len << 7;
+ if (gsm->len > gsm->mru) {
+ gsm->bad_size++;
+ gsm->state = GSM_SEARCH;
+ break;
+ }
+ gsm->count = 0;
+ if (!gsm->len)
+ gsm->state = GSM_FCS;
+ else
+ gsm->state = GSM_DATA;
+ break;
+ case GSM_DATA: /* Data */
+ gsm->buf[gsm->count++] = c;
+ if (gsm->count == gsm->len) {
+ /* Calculate final FCS for UI frames over all data */
+ if ((gsm->control & ~PF) != UIH) {
+ gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
+ gsm->count);
+ }
+ gsm->state = GSM_FCS;
+ }
+ break;
+ case GSM_FCS: /* FCS follows the packet */
+ gsm->fcs = gsm_fcs_add(gsm->fcs, c);
+ gsm->state = GSM_SSOF;
+ break;
+ case GSM_SSOF:
+ gsm->state = GSM_SEARCH;
+ if (c == GSM0_SOF)
+ gsm_queue(gsm);
+ else
+ gsm->bad_size++;
+ break;
+ default:
+ pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
+ break;
+ }
+}
+
+/**
+ * gsm1_receive - perform processing for non-transparency
+ * @gsm: gsm data for this ldisc instance
+ * @c: character
+ *
+ * Receive bytes in mode 1 (Advanced option)
+ */
+
+static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
+{
+ /* handle XON/XOFF */
+ if ((c & ISO_IEC_646_MASK) == XON) {
+ gsm->constipated = true;
+ return;
+ } else if ((c & ISO_IEC_646_MASK) == XOFF) {
+ gsm->constipated = false;
+ /* Kick the link in case it is idling */
+ gsmld_write_trigger(gsm);
+ return;
+ }
+ if (c == GSM1_SOF) {
+ /* EOF is only valid in frame if we have got to the data state */
+ if (gsm->state == GSM_DATA) {
+ if (gsm->count < 1) {
+ /* Missing FSC */
+ gsm->malformed++;
+ gsm->state = GSM_START;
+ return;
+ }
+ /* Remove the FCS from data */
+ gsm->count--;
+ if ((gsm->control & ~PF) != UIH) {
+ /* Calculate final FCS for UI frames over all
+ * data but FCS
+ */
+ gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
+ gsm->count);
+ }
+ /* Add the FCS itself to test against GOOD_FCS */
+ 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) {
+ if (gsm->state != GSM_SEARCH)
+ 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 = true;
+ 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 = false;
+ }
+ switch (gsm->state) {
+ case GSM_START: /* First byte after SOF */
+ gsm->address = 0;
+ gsm->state = GSM_ADDRESS;
+ gsm->fcs = INIT_FCS;
+ fallthrough;
+ 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;
+ default:
+ pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
+ break;
+ }
+}
+
+/**
+ * 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->state = GSM_SEARCH;
+ gsm->io_error++;
+}
+
+/**
+ * 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)
+{
+ int i;
+ struct gsm_dlci *dlci;
+ struct gsm_msg *txq, *ntxq;
+
+ gsm->dead = true;
+ mutex_lock(&gsm->mutex);
+
+ dlci = gsm->dlci[0];
+ if (dlci) {
+ if (disc && dlci->state != DLCI_CLOSED) {
+ gsm_dlci_begin_close(dlci);
+ wait_event(gsm->event, dlci->state == DLCI_CLOSED);
+ }
+ dlci->dead = true;
+ }
+
+ /* Finish outstanding timers, making sure they are done */
+ del_timer_sync(&gsm->kick_timer);
+ del_timer_sync(&gsm->t2_timer);
+
+ /* Finish writing to ldisc */
+ flush_work(&gsm->tx_work);
+
+ /* Free up any link layer users and finally the control channel */
+ if (gsm->has_devices) {
+ gsm_unregister_devices(gsm_tty_driver, gsm->num);
+ gsm->has_devices = false;
+ }
+ for (i = NUM_DLCI - 1; i >= 0; i--)
+ if (gsm->dlci[i])
+ gsm_dlci_release(gsm->dlci[i]);
+ mutex_unlock(&gsm->mutex);
+ /* Now wipe the queues */
+ tty_ldisc_flush(gsm->tty);
+ list_for_each_entry_safe(txq, ntxq, &gsm->tx_ctrl_list, list)
+ kfree(txq);
+ INIT_LIST_HEAD(&gsm->tx_ctrl_list);
+ list_for_each_entry_safe(txq, ntxq, &gsm->tx_data_list, list)
+ kfree(txq);
+ INIT_LIST_HEAD(&gsm->tx_data_list);
+}
+
+/**
+ * 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)
+{
+ struct gsm_dlci *dlci;
+ int ret;
+
+ dlci = gsm_dlci_alloc(gsm, 0);
+ if (dlci == NULL)
+ return -ENOMEM;
+
+ if (gsm->encoding == GSM_BASIC_OPT)
+ gsm->receive = gsm0_receive;
+ else
+ gsm->receive = gsm1_receive;
+
+ ret = gsm_register_devices(gsm_tty_driver, gsm->num);
+ if (ret)
+ return ret;
+
+ gsm->has_devices = true;
+ gsm->dead = false; /* Tty opens are now permissible */
+ return 0;
+}
+
+/**
+ * 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)
+{
+ int i;
+
+ for (i = 0; i < MAX_MUX; i++) {
+ if (gsm == gsm_mux[i]) {
+ gsm_mux[i] = NULL;
+ break;
+ }
+ }
+ mutex_destroy(&gsm->mutex);
+ kfree(gsm->txframe);
+ kfree(gsm->buf);
+ kfree(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)
+{
+ struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
+ gsm_free_mux(gsm);
+}
+
+static inline void mux_get(struct gsm_mux *gsm)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&gsm_mux_lock, flags);
+ kref_get(&gsm->ref);
+ spin_unlock_irqrestore(&gsm_mux_lock, flags);
+}
+
+static inline void mux_put(struct gsm_mux *gsm)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&gsm_mux_lock, flags);
+ kref_put(&gsm->ref, gsm_free_muxr);
+ spin_unlock_irqrestore(&gsm_mux_lock, flags);
+}
+
+static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
+{
+ return gsm->num * NUM_DLCI;
+}
+
+static inline unsigned int mux_line_to_num(unsigned int line)
+{
+ return line / NUM_DLCI;
+}
+
+/**
+ * gsm_alloc_mux - allocate a mux
+ *
+ * Creates a new mux ready for activation.
+ */
+
+static struct gsm_mux *gsm_alloc_mux(void)
+{
+ int i;
+ 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_MTU + PROT_OVERHEAD - 1), GFP_KERNEL);
+ if (gsm->txframe == NULL) {
+ kfree(gsm->buf);
+ kfree(gsm);
+ return NULL;
+ }
+ spin_lock_init(&gsm->lock);
+ mutex_init(&gsm->mutex);
+ kref_init(&gsm->ref);
+ INIT_LIST_HEAD(&gsm->tx_ctrl_list);
+ INIT_LIST_HEAD(&gsm->tx_data_list);
+ timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
+ timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
+ INIT_WORK(&gsm->tx_work, gsmld_write_task);
+ init_waitqueue_head(&gsm->event);
+ spin_lock_init(&gsm->control_lock);
+ spin_lock_init(&gsm->tx_lock);
+
+ gsm->t1 = T1;
+ gsm->t2 = T2;
+ gsm->n2 = N2;
+ gsm->ftype = UIH;
+ gsm->adaption = 1;
+ gsm->encoding = GSM_ADV_OPT;
+ gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
+ gsm->mtu = 64;
+ gsm->dead = true; /* Avoid early tty opens */
+
+ /* Store the instance to the mux array or abort if no space is
+ * available.
+ */
+ spin_lock(&gsm_mux_lock);
+ for (i = 0; i < MAX_MUX; i++) {
+ if (!gsm_mux[i]) {
+ gsm_mux[i] = gsm;
+ gsm->num = i;
+ break;
+ }
+ }
+ spin_unlock(&gsm_mux_lock);
+ if (i == MAX_MUX) {
+ mutex_destroy(&gsm->mutex);
+ kfree(gsm->txframe);
+ kfree(gsm->buf);
+ kfree(gsm);
+ return NULL;
+ }
+
+ return gsm;
+}
+
+static void gsm_copy_config_values(struct gsm_mux *gsm,
+ struct gsm_config *c)
+{
+ memset(c, 0, sizeof(*c));
+ c->adaption = gsm->adaption;
+ c->encapsulation = gsm->encoding;
+ c->initiator = gsm->initiator;
+ c->t1 = gsm->t1;
+ c->t2 = gsm->t2;
+ c->t3 = 0; /* Not supported */
+ c->n2 = gsm->n2;
+ if (gsm->ftype == UIH)
+ c->i = 1;
+ else
+ c->i = 2;
+ pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
+ c->mru = gsm->mru;
+ c->mtu = gsm->mtu;
+ c->k = 0;
+}
+
+static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
+{
+ int ret = 0;
+ 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 > 255)
+ 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. On the first time there is no DLCI[0]
+ * and closing or cleaning up is not necessary.
+ */
+ if (need_close || need_restart)
+ gsm_cleanup_mux(gsm, true);
+
+ gsm->initiator = c->initiator;
+ gsm->mru = c->mru;
+ gsm->mtu = c->mtu;
+ gsm->encoding = c->encapsulation ? GSM_ADV_OPT : GSM_BASIC_OPT;
+ gsm->adaption = c->adaption;
+ gsm->n2 = c->n2;
+
+ if (c->i == 1)
+ gsm->ftype = UIH;
+ else if (c->i == 2)
+ gsm->ftype = UI;
+
+ if (c->t1)
+ gsm->t1 = c->t1;
+ if (c->t2)
+ gsm->t2 = c->t2;
+
+ /*
+ * FIXME: We need to separate activation/deactivation from adding
+ * and removing from the mux array
+ */
+ if (gsm->dead) {
+ ret = gsm_activate_mux(gsm);
+ if (ret)
+ return ret;
+ if (gsm->initiator)
+ gsm_dlci_begin_open(gsm->dlci[0]);
+ }
+ return 0;
+}
+
+/**
+ * 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 & DBG_DATA)
+ gsm_hex_dump_bytes(__func__, data, len);
+ return gsm->tty->ops->write(gsm->tty, data, len);
+}
+
+
+/**
+ * gsmld_write_trigger - schedule ldisc write task
+ * @gsm: our mux
+ */
+static void gsmld_write_trigger(struct gsm_mux *gsm)
+{
+ if (!gsm || !gsm->dlci[0] || gsm->dlci[0]->dead)
+ return;
+ schedule_work(&gsm->tx_work);
+}
+
+
+/**
+ * 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)
+{
+ struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work);
+ unsigned long flags;
+ int i, ret;
+
+ /* All outstanding control channel and control messages and one data
+ * frame is sent.
+ */
+ ret = -ENODEV;
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ if (gsm->tty)
+ ret = gsm_data_kick(gsm);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+ if (ret >= 0)
+ for (i = 0; i < NUM_DLCI; i++)
+ if (gsm->dlci[i])
+ tty_port_tty_wakeup(&gsm->dlci[i]->port);
+}
+
+/**
+ * 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)
+{
+ gsm->tty = tty_kref_get(tty);
+ /* Turn off tty XON/XOFF handling to handle it explicitly. */
+ gsm->old_c_iflag = tty->termios.c_iflag;
+ tty->termios.c_iflag &= (IXON | IXOFF);
+}
+
+/**
+ * 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)
+{
+ WARN_ON(tty != gsm->tty);
+ /* Restore tty XON/XOFF handling. */
+ gsm->tty->termios.c_iflag = gsm->old_c_iflag;
+ tty_kref_put(gsm->tty);
+ gsm->tty = NULL;
+}
+
+static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+ const char *fp, int count)
+{
+ struct gsm_mux *gsm = tty->disc_data;
+ char flags = TTY_NORMAL;
+
+ if (debug & DBG_DATA)
+ gsm_hex_dump_bytes(__func__, cp, count);
+
+ for (; count; count--, cp++) {
+ if (fp)
+ flags = *fp++;
+ switch (flags) {
+ case TTY_NORMAL:
+ if (gsm->receive)
+ gsm->receive(gsm, *cp);
+ break;
+ case TTY_OVERRUN:
+ case TTY_BREAK:
+ case TTY_PARITY:
+ case TTY_FRAME:
+ gsm_error(gsm);
+ break;
+ default:
+ WARN_ONCE(1, "%s: unknown flag %d\n",
+ tty_name(tty), flags);
+ break;
+ }
+ }
+ /* FASYNC if needed ? */
+ /* If clogged call tty_throttle(tty); */
+}
+
+/**
+ * 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;
+
+ /* The ldisc locks and closes the port before calling our close. This
+ * means we have no way to do a proper disconnect. We will not bother
+ * to do one.
+ */
+ gsm_cleanup_mux(gsm, false);
+
+ gsmld_detach_gsm(tty, gsm);
+
+ gsmld_flush_buffer(tty);
+ /* Do other clean up here */
+ mux_put(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 = GSM_ADV_OPT;
+ gsmld_attach_gsm(tty, gsm);
+
+ return 0;
+}
+
+/**
+ * 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 */
+ gsmld_write_trigger(gsm);
+}
+
+/**
+ * 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,
+ unsigned char *buf, size_t nr,
+ void **cookie, unsigned long offset)
+{
+ 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)
+{
+ struct gsm_mux *gsm = tty->disc_data;
+ unsigned long flags;
+ int space;
+ int ret;
+
+ if (!gsm)
+ return -ENODEV;
+
+ ret = -ENOBUFS;
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ space = tty_write_room(tty);
+ if (space >= nr)
+ ret = tty->ops->write(tty, buf, nr);
+ else
+ set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+ return ret;
+}
+
+/**
+ * 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)
+{
+ __poll_t mask = 0;
+ struct gsm_mux *gsm = tty->disc_data;
+
+ poll_wait(file, &tty->read_wait, wait);
+ poll_wait(file, &tty->write_wait, wait);
+
+ if (gsm->dead)
+ mask |= EPOLLHUP;
+ if (tty_hung_up_p(file))
+ mask |= EPOLLHUP;
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+ mask |= EPOLLHUP;
+ if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
+ mask |= EPOLLOUT | EPOLLWRNORM;
+ return mask;
+}
+
+static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd,
+ unsigned long arg)
+{
+ struct gsm_config c;
+ struct gsm_mux *gsm = tty->disc_data;
+ unsigned int base;
+
+ switch (cmd) {
+ case GSMIOC_GETCONF:
+ gsm_copy_config_values(gsm, &c);
+ if (copy_to_user((void __user *)arg, &c, sizeof(c)))
+ return -EFAULT;
+ return 0;
+ case GSMIOC_SETCONF:
+ if (copy_from_user(&c, (void __user *)arg, sizeof(c)))
+ return -EFAULT;
+ return gsm_config(gsm, &c);
+ case GSMIOC_GETFIRST:
+ base = mux_num_to_base(gsm);
+ return put_user(base + 1, (__u32 __user *)arg);
+ default:
+ return n_tty_ioctl_helper(tty, cmd, arg);
+ }
+}
+
+/*
+ * Network interface
+ *
+ */
+
+static int gsm_mux_net_open(struct net_device *net)
+{
+ pr_debug("%s called\n", __func__);
+ netif_start_queue(net);
+ return 0;
+}
+
+static int gsm_mux_net_close(struct net_device *net)
+{
+ netif_stop_queue(net);
+ return 0;
+}
+
+static void dlci_net_free(struct gsm_dlci *dlci)
+{
+ if (!dlci->net) {
+ WARN_ON(1);
+ return;
+ }
+ dlci->adaption = dlci->prev_adaption;
+ dlci->data = dlci->prev_data;
+ free_netdev(dlci->net);
+ dlci->net = NULL;
+}
+static void net_free(struct kref *ref)
+{
+ struct gsm_mux_net *mux_net;
+ struct gsm_dlci *dlci;
+
+ mux_net = container_of(ref, struct gsm_mux_net, ref);
+ dlci = mux_net->dlci;
+
+ if (dlci->net) {
+ unregister_netdev(dlci->net);
+ dlci_net_free(dlci);
+ }
+}
+
+static inline void muxnet_get(struct gsm_mux_net *mux_net)
+{
+ kref_get(&mux_net->ref);
+}
+
+static inline void muxnet_put(struct gsm_mux_net *mux_net)
+{
+ kref_put(&mux_net->ref, net_free);
+}
+
+static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
+ struct net_device *net)
+{
+ struct gsm_mux_net *mux_net = netdev_priv(net);
+ struct gsm_dlci *dlci = mux_net->dlci;
+ muxnet_get(mux_net);
+
+ skb_queue_head(&dlci->skb_list, skb);
+ net->stats.tx_packets++;
+ net->stats.tx_bytes += skb->len;
+ gsm_dlci_data_kick(dlci);
+ /* And tell the kernel when the last transmit started. */
+ netif_trans_update(net);
+ muxnet_put(mux_net);
+ return NETDEV_TX_OK;
+}
+
+/* called when a packet did not ack after watchdogtimeout */
+static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue)
+{
+ /* Tell syslog we are hosed. */
+ dev_dbg(&net->dev, "Tx timed out.\n");
+
+ /* Update statistics */
+ net->stats.tx_errors++;
+}
+
+static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
+ const unsigned char *in_buf, int size)
+{
+ struct net_device *net = dlci->net;
+ struct sk_buff *skb;
+ struct gsm_mux_net *mux_net = netdev_priv(net);
+ muxnet_get(mux_net);
+
+ /* Allocate an sk_buff */
+ skb = dev_alloc_skb(size + NET_IP_ALIGN);
+ if (!skb) {
+ /* We got no receive buffer. */
+ net->stats.rx_dropped++;
+ muxnet_put(mux_net);
+ return;
+ }
+ skb_reserve(skb, NET_IP_ALIGN);
+ skb_put_data(skb, in_buf, size);
+
+ skb->dev = net;
+ skb->protocol = htons(ETH_P_IP);
+
+ /* Ship it off to the kernel */
+ netif_rx(skb);
+
+ /* update out statistics */
+ net->stats.rx_packets++;
+ net->stats.rx_bytes += size;
+ muxnet_put(mux_net);
+ return;
+}
+
+static void gsm_mux_net_init(struct net_device *net)
+{
+ static const struct net_device_ops gsm_netdev_ops = {
+ .ndo_open = gsm_mux_net_open,
+ .ndo_stop = gsm_mux_net_close,
+ .ndo_start_xmit = gsm_mux_net_start_xmit,
+ .ndo_tx_timeout = gsm_mux_net_tx_timeout,
+ };
+
+ net->netdev_ops = &gsm_netdev_ops;
+
+ /* fill in the other fields */
+ net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
+ net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
+ net->type = ARPHRD_NONE;
+ net->tx_queue_len = 10;
+}
+
+
+/* caller holds the dlci mutex */
+static void gsm_destroy_network(struct gsm_dlci *dlci)
+{
+ struct gsm_mux_net *mux_net;
+
+ pr_debug("destroy network interface\n");
+ if (!dlci->net)
+ return;
+ mux_net = netdev_priv(dlci->net);
+ muxnet_put(mux_net);
+}
+
+
+/* caller holds the dlci mutex */
+static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
+{
+ char *netname;
+ int retval = 0;
+ struct net_device *net;
+ struct gsm_mux_net *mux_net;
+
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
+ /* Already in a non tty mode */
+ if (dlci->adaption > 2)
+ return -EBUSY;
+
+ if (nc->protocol != htons(ETH_P_IP))
+ return -EPROTONOSUPPORT;
+
+ if (nc->adaption != 3 && nc->adaption != 4)
+ return -EPROTONOSUPPORT;
+
+ pr_debug("create network interface\n");
+
+ netname = "gsm%d";
+ if (nc->if_name[0] != '\0')
+ netname = nc->if_name;
+ net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
+ NET_NAME_UNKNOWN, gsm_mux_net_init);
+ if (!net) {
+ pr_err("alloc_netdev failed\n");
+ return -ENOMEM;
+ }
+ net->mtu = dlci->gsm->mtu;
+ net->min_mtu = 8;
+ net->max_mtu = dlci->gsm->mtu;
+ mux_net = netdev_priv(net);
+ mux_net->dlci = dlci;
+ kref_init(&mux_net->ref);
+ strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
+
+ /* reconfigure dlci for network */
+ dlci->prev_adaption = dlci->adaption;
+ dlci->prev_data = dlci->data;
+ dlci->adaption = nc->adaption;
+ dlci->data = gsm_mux_rx_netchar;
+ dlci->net = net;
+
+ pr_debug("register netdev\n");
+ retval = register_netdev(net);
+ if (retval) {
+ pr_err("network register fail %d\n", retval);
+ dlci_net_free(dlci);
+ return retval;
+ }
+ return net->ifindex; /* return network index */
+}
+
+/* Line discipline for real tty */
+static struct tty_ldisc_ops tty_ldisc_packet = {
+ .owner = THIS_MODULE,
+ .num = N_GSM0710,
+ .name = "n_gsm",
+ .open = gsmld_open,
+ .close = gsmld_close,
+ .flush_buffer = gsmld_flush_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
+ */
+
+/**
+ * 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)
+{
+ struct gsm_mux *gsm = dlci->gsm;
+ unsigned long flags;
+
+ if (dlci->state != DLCI_OPEN || dlci->adaption != 2)
+ return;
+
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ gsm_dlci_modem_output(gsm, dlci, brk);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+}
+
+/**
+ * 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)
+{
+ u8 modembits[3];
+ struct gsm_control *ctrl;
+ int len = 2;
+
+ if (dlci->gsm->encoding != GSM_BASIC_OPT)
+ return 0;
+
+ modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */
+ if (!brk) {
+ modembits[1] = (gsm_encode_modem(dlci) << 1) | EA;
+ } else {
+ modembits[1] = gsm_encode_modem(dlci) << 1;
+ modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */
+ len++;
+ }
+ ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len);
+ if (ctrl == NULL)
+ return -ENOMEM;
+ return gsm_control_wait(dlci->gsm, ctrl);
+}
+
+/**
+ * gsm_modem_update - send modem status line state
+ * @dlci: channel
+ * @brk: break signal
+ */
+
+static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
+{
+ if (dlci->gsm->dead)
+ return -EL2HLT;
+ if (dlci->adaption == 2) {
+ /* Send convergence layer type 2 empty data frame. */
+ gsm_modem_upd_via_data(dlci, brk);
+ return 0;
+ } else if (dlci->gsm->encoding == GSM_BASIC_OPT) {
+ /* Send as MSC control message. */
+ return gsm_modem_upd_via_msc(dlci, brk);
+ }
+
+ /* Modem status lines are not supported. */
+ return -EPROTONOSUPPORT;
+}
+
+static int gsm_carrier_raised(struct tty_port *port)
+{
+ struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
+ struct gsm_mux *gsm = dlci->gsm;
+
+ /* Not yet open so no carrier info */
+ if (dlci->state != DLCI_OPEN)
+ return 0;
+ if (debug & DBG_CD_ON)
+ return 1;
+
+ /*
+ * Basic mode with control channel in ADM mode may not respond
+ * to CMD_MSC at all and modem_rx is empty.
+ */
+ if (gsm->encoding == GSM_BASIC_OPT &&
+ gsm->dlci[0]->mode == DLCI_MODE_ADM && !dlci->modem_rx)
+ 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;
+ gsm_modem_update(dlci, 0);
+ }
+}
+
+static const struct tty_port_operations gsm_port_ops = {
+ .carrier_raised = gsm_carrier_raised,
+ .dtr_rts = gsm_dtr_rts,
+ .destruct = gsm_dlci_free,
+};
+
+static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ struct gsm_mux *gsm;
+ struct gsm_dlci *dlci;
+ unsigned int line = tty->index;
+ unsigned int mux = mux_line_to_num(line);
+ bool alloc = false;
+ int ret;
+
+ 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;
+ /* If DLCI 0 is not yet fully open return an error.
+ This is ok from a locking
+ perspective as we don't have to worry about this
+ if DLCI0 is lost */
+ mutex_lock(&gsm->mutex);
+ if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
+ mutex_unlock(&gsm->mutex);
+ return -EL2NSYNC;
+ }
+ dlci = gsm->dlci[line];
+ if (dlci == NULL) {
+ alloc = true;
+ dlci = gsm_dlci_alloc(gsm, line);
+ }
+ if (dlci == NULL) {
+ mutex_unlock(&gsm->mutex);
+ return -ENOMEM;
+ }
+ ret = tty_port_install(&dlci->port, driver, tty);
+ if (ret) {
+ if (alloc)
+ dlci_put(dlci);
+ mutex_unlock(&gsm->mutex);
+ return ret;
+ }
+
+ dlci_get(dlci);
+ dlci_get(gsm->dlci[0]);
+ mux_get(gsm);
+ tty->driver_data = dlci;
+ mutex_unlock(&gsm->mutex);
+
+ return 0;
+}
+
+static int gsmtty_open(struct tty_struct *tty, struct file *filp)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ struct tty_port *port = &dlci->port;
+ struct gsm_mux *gsm = dlci->gsm;
+
+ port->count++;
+ 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 */
+ tty_port_set_initialized(port, 1);
+ /* Start sending off SABM messages */
+ if (gsm->initiator)
+ gsm_dlci_begin_open(dlci);
+ else
+ gsm_dlci_set_opening(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 (dlci->state == DLCI_CLOSED)
+ return;
+ mutex_lock(&dlci->mutex);
+ gsm_destroy_network(dlci);
+ mutex_unlock(&dlci->mutex);
+ if (tty_port_close_start(&dlci->port, tty, filp) == 0)
+ return;
+ gsm_dlci_begin_close(dlci);
+ if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
+ tty_port_lower_dtr_rts(&dlci->port);
+ tty_port_close_end(&dlci->port, tty);
+ tty_port_tty_set(&dlci->port, NULL);
+ return;
+}
+
+static void gsmtty_hangup(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return;
+ tty_port_hangup(&dlci->port);
+ gsm_dlci_begin_close(dlci);
+}
+
+static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
+ int len)
+{
+ int sent;
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return -EINVAL;
+ /* Stuff the bytes into the fifo queue */
+ sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock);
+ /* Need to kick the channel */
+ gsm_dlci_data_kick(dlci);
+ return sent;
+}
+
+static unsigned int gsmtty_write_room(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return 0;
+ return kfifo_avail(&dlci->fifo);
+}
+
+static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return 0;
+ return kfifo_len(&dlci->fifo);
+}
+
+static void gsmtty_flush_buffer(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ unsigned long flags;
+
+ if (dlci->state == DLCI_CLOSED)
+ return;
+ /* 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 */
+ spin_lock_irqsave(&dlci->lock, flags);
+ kfifo_reset(&dlci->fifo);
+ spin_unlock_irqrestore(&dlci->lock, flags);
+ /* 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 gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return -EINVAL;
+ return dlci->modem_rx;
+}
+
+static int gsmtty_tiocmset(struct tty_struct *tty,
+ unsigned int set, unsigned int clear)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ unsigned int modem_tx = dlci->modem_tx;
+
+ if (dlci->state == DLCI_CLOSED)
+ return -EINVAL;
+ modem_tx &= ~clear;
+ modem_tx |= set;
+
+ if (modem_tx != dlci->modem_tx) {
+ dlci->modem_tx = modem_tx;
+ return gsm_modem_update(dlci, 0);
+ }
+ return 0;
+}
+
+
+static int gsmtty_ioctl(struct tty_struct *tty,
+ unsigned int cmd, unsigned long arg)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ struct gsm_netconfig nc;
+ int index;
+
+ if (dlci->state == DLCI_CLOSED)
+ return -EINVAL;
+ switch (cmd) {
+ case GSMIOC_ENABLE_NET:
+ if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
+ return -EFAULT;
+ nc.if_name[IFNAMSIZ-1] = '\0';
+ /* return net interface index or error code */
+ mutex_lock(&dlci->mutex);
+ index = gsm_create_network(dlci, &nc);
+ mutex_unlock(&dlci->mutex);
+ if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
+ return -EFAULT;
+ return index;
+ case GSMIOC_DISABLE_NET:
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+ mutex_lock(&dlci->mutex);
+ gsm_destroy_network(dlci);
+ mutex_unlock(&dlci->mutex);
+ return 0;
+ default:
+ return -ENOIOCTLCMD;
+ }
+}
+
+static void gsmtty_set_termios(struct tty_struct *tty,
+ const struct ktermios *old)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return;
+ /* 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 (dlci->state == DLCI_CLOSED)
+ return;
+ if (C_CRTSCTS(tty))
+ dlci->modem_tx &= ~TIOCM_RTS;
+ dlci->throttled = true;
+ /* Send an MSC with RTS cleared */
+ gsm_modem_update(dlci, 0);
+}
+
+static void gsmtty_unthrottle(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ if (dlci->state == DLCI_CLOSED)
+ return;
+ if (C_CRTSCTS(tty))
+ dlci->modem_tx |= TIOCM_RTS;
+ dlci->throttled = false;
+ /* Send an MSC with RTS set */
+ gsm_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 (dlci->state == DLCI_CLOSED)
+ return -EINVAL;
+
+ 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 gsm_modem_update(dlci, encode);
+}
+
+static void gsmtty_cleanup(struct tty_struct *tty)
+{
+ struct gsm_dlci *dlci = tty->driver_data;
+ struct gsm_mux *gsm = dlci->gsm;
+
+ dlci_put(dlci);
+ dlci_put(gsm->dlci[0]);
+ mux_put(gsm);
+}
+
+/* Virtual ttys for the demux */
+static const struct tty_operations gsmtty_ops = {
+ .install = gsmtty_install,
+ .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,
+ .cleanup = gsmtty_cleanup,
+};
+
+
+
+static int __init gsm_init(void)
+{
+ /* Fill in our line protocol discipline, and register it */
+ int status = tty_register_ldisc(&tty_ldisc_packet);
+ if (status != 0) {
+ pr_err("n_gsm: can't register line discipline (err = %d)\n",
+ status);
+ return status;
+ }
+
+ gsm_tty_driver = tty_alloc_driver(GSM_TTY_MINORS, TTY_DRIVER_REAL_RAW |
+ TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_HARDWARE_BREAK);
+ if (IS_ERR(gsm_tty_driver)) {
+ pr_err("gsm_init: tty allocation failed.\n");
+ status = PTR_ERR(gsm_tty_driver);
+ goto err_unreg_ldisc;
+ }
+ 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->init_termios = tty_std_termios;
+ /* Fixme */
+ gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
+ tty_set_operations(gsm_tty_driver, &gsmtty_ops);
+
+ if (tty_register_driver(gsm_tty_driver)) {
+ pr_err("gsm_init: tty registration failed.\n");
+ status = -EBUSY;
+ goto err_put_driver;
+ }
+ pr_debug("gsm_init: loaded as %d,%d.\n",
+ gsm_tty_driver->major, gsm_tty_driver->minor_start);
+ return 0;
+err_put_driver:
+ tty_driver_kref_put(gsm_tty_driver);
+err_unreg_ldisc:
+ tty_unregister_ldisc(&tty_ldisc_packet);
+ return status;
+}
+
+static void __exit gsm_exit(void)
+{
+ tty_unregister_ldisc(&tty_ldisc_packet);
+ tty_unregister_driver(gsm_tty_driver);
+ tty_driver_kref_put(gsm_tty_driver);
+}
+
+module_init(gsm_init);
+module_exit(gsm_exit);
+
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_GSM0710);