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linux / linux / kernel / git / torvalds / linux / 3bfd8fcab548659e3a77000b2302c62a47ab2824 / . / drivers / tty / n_gsm.c
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// 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 = gsm->dlci[0];
struct gsm_msg *txq, *ntxq;
gsm->dead = true;
mutex_lock(&gsm->mutex);
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. */