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/*
* PPP synchronous tty channel driver for Linux.
*
* This is a ppp channel driver that can be used with tty device drivers
* that are frame oriented, such as synchronous HDLC devices.
*
* Complete PPP frames without encoding/decoding are exchanged between
* the channel driver and the device driver.
*
* The async map IOCTL codes are implemented to keep the user mode
* applications happy if they call them. Synchronous PPP does not use
* the async maps.
*
* Copyright 1999 Paul Mackerras.
*
* Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* This driver provides the encapsulation and framing for sending
* and receiving PPP frames over sync serial lines. It relies on
* the generic PPP layer to give it frames to send and to process
* received frames. It implements the PPP line discipline.
*
* Part of the code in this driver was inspired by the old async-only
* PPP driver, written by Michael Callahan and Al Longyear, and
* subsequently hacked by Paul Mackerras.
*
* ==FILEVERSION 20040616==
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/tty.h>
#include <linux/netdevice.h>
#include <linux/poll.h>
#include <linux/ppp_defs.h>
#include <linux/if_ppp.h>
#include <linux/ppp_channel.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#define PPP_VERSION "2.4.2"
/* Structure for storing local state. */
struct syncppp {
struct tty_struct *tty;
unsigned int flags;
unsigned int rbits;
int mru;
spinlock_t xmit_lock;
spinlock_t recv_lock;
unsigned long xmit_flags;
u32 xaccm[8];
u32 raccm;
unsigned int bytes_sent;
unsigned int bytes_rcvd;
struct sk_buff *tpkt;
unsigned long last_xmit;
struct sk_buff_head rqueue;
struct tasklet_struct tsk;
atomic_t refcnt;
struct completion dead_cmp;
struct ppp_channel chan; /* interface to generic ppp layer */
};
/* Bit numbers in xmit_flags */
#define XMIT_WAKEUP 0
#define XMIT_FULL 1
/* Bits in rbits */
#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
#define PPPSYNC_MAX_RQLEN 32 /* arbitrary */
/*
* Prototypes.
*/
static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *);
static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd,
unsigned long arg);
static void ppp_sync_process(unsigned long arg);
static int ppp_sync_push(struct syncppp *ap);
static void ppp_sync_flush_output(struct syncppp *ap);
static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
char *flags, int count);
static struct ppp_channel_ops sync_ops = {
ppp_sync_send,
ppp_sync_ioctl
};
/*
* Utility procedures to print a buffer in hex/ascii
*/
static void
ppp_print_hex (register __u8 * out, const __u8 * in, int count)
{
register __u8 next_ch;
static const char hex[] = "0123456789ABCDEF";
while (count-- > 0) {
next_ch = *in++;
*out++ = hex[(next_ch >> 4) & 0x0F];
*out++ = hex[next_ch & 0x0F];
++out;
}
}
static void
ppp_print_char (register __u8 * out, const __u8 * in, int count)
{
register __u8 next_ch;
while (count-- > 0) {
next_ch = *in++;
if (next_ch < 0x20 || next_ch > 0x7e)
*out++ = '.';
else {
*out++ = next_ch;
if (next_ch == '%') /* printk/syslogd has a bug !! */
*out++ = '%';
}
}
*out = '\0';
}
static void
ppp_print_buffer (const char *name, const __u8 *buf, int count)
{
__u8 line[44];
if (name != NULL)
printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count);
while (count > 8) {
memset (line, 32, 44);
ppp_print_hex (line, buf, 8);
ppp_print_char (&line[8 * 3], buf, 8);
printk(KERN_DEBUG "%s\n", line);
count -= 8;
buf += 8;
}
if (count > 0) {
memset (line, 32, 44);
ppp_print_hex (line, buf, count);
ppp_print_char (&line[8 * 3], buf, count);
printk(KERN_DEBUG "%s\n", line);
}
}
/*
* Routines implementing the synchronous PPP line discipline.
*/
/*
* We have a potential race on dereferencing tty->disc_data,
* because the tty layer provides no locking at all - thus one
* cpu could be running ppp_synctty_receive while another
* calls ppp_synctty_close, which zeroes tty->disc_data and
* frees the memory that ppp_synctty_receive is using. The best
* way to fix this is to use a rwlock in the tty struct, but for now
* we use a single global rwlock for all ttys in ppp line discipline.
*
* FIXME: Fixed in tty_io nowdays.
*/
static DEFINE_RWLOCK(disc_data_lock);
static struct syncppp *sp_get(struct tty_struct *tty)
{
struct syncppp *ap;
read_lock(&disc_data_lock);
ap = tty->disc_data;
if (ap != NULL)
atomic_inc(&ap->refcnt);
read_unlock(&disc_data_lock);
return ap;
}
static void sp_put(struct syncppp *ap)
{
if (atomic_dec_and_test(&ap->refcnt))
complete(&ap->dead_cmp);
}
/*
* Called when a tty is put into sync-PPP line discipline.
*/
static int
ppp_sync_open(struct tty_struct *tty)
{
struct syncppp *ap;
int err;
if (tty->ops->write == NULL)
return -EOPNOTSUPP;
ap = kzalloc(sizeof(*ap), GFP_KERNEL);
err = -ENOMEM;
if (!ap)
goto
|