isdn_tty.c

讲述linux的初始化过程

/* $Id: isdn_tty.c,v 1.94 2000/11/25 17:00:59 kai Exp $

 * Linux ISDN subsystem, tty functions and AT-command emulator (linklevel).
 *
 * Copyright 1994-1999  by Fritz Elfert ([e-mail])
 * Copyright 1995,96    by Thinking Objects Software GmbH Wuerzburg
 *
 * 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, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */
#undef ISDN_TTY_STAT_DEBUG

#define __NO_VERSION__
#include <linux/config.h>
#include <linux/module.h>
#include <linux/isdn.h>
#include "isdn_common.h"
#include "isdn_tty.h"
#ifdef CONFIG_ISDN_AUDIO
#include "isdn_audio.h"
#define VBUF 0x3e0
#define VBUFX (VBUF/16)
#endif

#define FIX_FILE_TRANSFER
#define	DUMMY_HAYES_AT

/* Prototypes */

static int isdn_tty_edit_at(const char *, int, modem_info *, int);
static void isdn_tty_check_esc(const u_char *, u_char, int, int *, int *, int);
static void isdn_tty_modem_reset_regs(modem_info *, int);
static void isdn_tty_cmd_ATA(modem_info *);
static void isdn_tty_flush_buffer(struct tty_struct *);
static void isdn_tty_modem_result(int, modem_info *);
#ifdef CONFIG_ISDN_AUDIO
static int isdn_tty_countDLE(unsigned char *, int);
#endif

/* Leave this unchanged unless you know what you do! */
#define MODEM_PARANOIA_CHECK
#define MODEM_DO_RESTART

#ifdef CONFIG_DEVFS_FS
static char *isdn_ttyname_ttyI = "isdn/ttyI%d";
static char *isdn_ttyname_cui = "isdn/cui%d";
#else
static char *isdn_ttyname_ttyI = "ttyI";
static char *isdn_ttyname_cui = "cui";
#endif

static int bit2si[8] =
{1, 5, 7, 7, 7, 7, 7, 7};
static int si2bit[8] =
{4, 1, 4, 4, 4, 4, 4, 4};

char *isdn_tty_revision = "$Revision: 1.94 $";


/* isdn_tty_try_read() is called from within isdn_tty_rcv_skb()
 * to stuff incoming data directly into a tty's flip-buffer. This
 * is done to speed up tty-receiving if the receive-queue is empty.
 * This routine MUST be called with interrupts off.
 * Return:
 *  1 = Success
 *  0 = Failure, data has to be buffered and later processed by
 *      isdn_tty_readmodem().
 */
static int
isdn_tty_try_read(modem_info * info, struct sk_buff *skb)
{
	int c;
	int len;
	struct tty_struct *tty;

	if (info->online) {
		if ((tty = info->tty)) {
			if (info->mcr & UART_MCR_RTS) {
				c = TTY_FLIPBUF_SIZE - tty->flip.count;
				len = skb->len
#ifdef CONFIG_ISDN_AUDIO
					+ ISDN_AUDIO_SKB_DLECOUNT(skb)
#endif
					;
				if (c >= len) {
#ifdef CONFIG_ISDN_AUDIO
					if (ISDN_AUDIO_SKB_DLECOUNT(skb))
						while (skb->len--) {
							if (*skb->data == DLE)
								tty_insert_flip_char(tty, DLE, 0);
							tty_insert_flip_char(tty, *skb->data++, 0);
					} else {
#endif
						memcpy(tty->flip.char_buf_ptr,
						       skb->data, len);
						tty->flip.count += len;
						tty->flip.char_buf_ptr += len;
						memset(tty->flip.flag_buf_ptr, 0, len);
						tty->flip.flag_buf_ptr += len;
#ifdef CONFIG_ISDN_AUDIO
					}
#endif
					if (info->emu.mdmreg[REG_CPPP] & BIT_CPPP)
						tty->flip.flag_buf_ptr[len - 1] = 0xff;
					queue_task(&tty->flip.tqueue, &tq_timer);
					kfree_skb(skb);
					return 1;
				}
			}
		}
	}
	return 0;
}

/* isdn_tty_readmodem() is called periodically from within timer-interrupt.
 * It tries getting received data from the receive queue an stuff it into
 * the tty's flip-buffer.
 */
void
isdn_tty_readmodem(void)
{
	int resched = 0;
	int midx;
	int i;
	int c;
	int r;
	ulong flags;
	struct tty_struct *tty;
	modem_info *info;

	for (i = 0; i < ISDN_MAX_CHANNELS; i++) {
		if ((midx = dev->m_idx[i]) >= 0) {
			info = &dev->mdm.info[midx];
			if (info->online) {
				r = 0;
#ifdef CONFIG_ISDN_AUDIO
				isdn_audio_eval_dtmf(info);
				if ((info->vonline & 1) && (info->emu.vpar[1]))
					isdn_audio_eval_silence(info);
#endif
				if ((tty = info->tty)) {
					if (info->mcr & UART_MCR_RTS) {
						c = TTY_FLIPBUF_SIZE - tty->flip.count;
						if (c > 0) {
							save_flags(flags);
							cli();
							r = isdn_readbchan(info->isdn_driver, info->isdn_channel,
									   tty->flip.char_buf_ptr,
									   tty->flip.flag_buf_ptr, c, 0);
							/* CISCO AsyncPPP Hack */
							if (!(info->emu.mdmreg[REG_CPPP] & BIT_CPPP))
								memset(tty->flip.flag_buf_ptr, 0, r);
							tty->flip.count += r;
							tty->flip.flag_buf_ptr += r;
							tty->flip.char_buf_ptr += r;
							if (r)
								queue_task(&tty->flip.tqueue, &tq_timer);
							restore_flags(flags);
						}
					} else
						r = 1;
				} else
					r = 1;
				if (r) {
					info->rcvsched = 0;
					resched = 1;
				} else
					info->rcvsched = 1;
			}
		}
	}
	if (!resched)
		isdn_timer_ctrl(ISDN_TIMER_MODEMREAD, 0);
}

int
isdn_tty_rcv_skb(int i, int di, int channel, struct sk_buff *skb)
{
	ulong flags;
	int midx;
#ifdef CONFIG_ISDN_AUDIO
	int ifmt;
#endif
	modem_info *info;

	if ((midx = dev->m_idx[i]) < 0) {
		/* if midx is invalid, packet is not for tty */
		return 0;
	}
	info = &dev->mdm.info[midx];
#ifdef CONFIG_ISDN_AUDIO
	ifmt = 1;
	
	if ((info->vonline) && (!info->emu.vpar[4]))
		isdn_audio_calc_dtmf(info, skb->data, skb->len, ifmt);
	if ((info->vonline & 1) && (info->emu.vpar[1]))
		isdn_audio_calc_silence(info, skb->data, skb->len, ifmt);
#endif
	if ((info->online < 2)
#ifdef CONFIG_ISDN_AUDIO
	    && (!(info->vonline & 1))
#endif
		) {
		/* If Modem not listening, drop data */
		kfree_skb(skb);
		return 1;
	}
	if (info->emu.mdmreg[REG_T70] & BIT_T70) {
		if (info->emu.mdmreg[REG_T70] & BIT_T70_EXT) {
			/* T.70 decoding: throw away the T.70 header (2 or 4 bytes)   */
			if (skb->data[0] == 3) /* pure data packet -> 4 byte headers  */
				skb_pull(skb, 4);
			else
				if (skb->data[0] == 1) /* keepalive packet -> 2 byte hdr  */
					skb_pull(skb, 2);
		} else
			/* T.70 decoding: Simply throw away the T.70 header (4 bytes) */
			if ((skb->data[0] == 1) && ((skb->data[1] == 0) || (skb->data[1] == 1)))
				skb_pull(skb, 4);
	}
#ifdef CONFIG_ISDN_AUDIO
	if (skb_headroom(skb) < sizeof(isdn_audio_skb)) {
		printk(KERN_WARNING
		       "isdn_audio: insufficient skb_headroom, dropping\n");
		kfree_skb(skb);
		return 1;
	}
	ISDN_AUDIO_SKB_DLECOUNT(skb) = 0;
	ISDN_AUDIO_SKB_LOCK(skb) = 0;
	if (info->vonline & 1) {
		/* voice conversion/compression */
		switch (info->emu.vpar[3]) {
			case 2:
			case 3:
			case 4:
				/* adpcm
				 * Since compressed data takes less
				 * space, we can overwrite the buffer.
				 */
				skb_trim(skb, isdn_audio_xlaw2adpcm(info->adpcmr,
								    ifmt,
								    skb->data,
								    skb->data,
								    skb->len));
				break;
			case 5:
				/* a-law */
				if (!ifmt)
					isdn_audio_ulaw2alaw(skb->data, skb->len);
				break;
			case 6:
				/* u-law */
				if (ifmt)
					isdn_audio_alaw2ulaw(skb->data, skb->len);
				break;
		}
		ISDN_AUDIO_SKB_DLECOUNT(skb) =
			isdn_tty_countDLE(skb->data, skb->len);
	}
#ifdef CONFIG_ISDN_TTY_FAX
	else {
		if (info->faxonline & 2) {
			isdn_tty_fax_bitorder(info, skb);
			ISDN_AUDIO_SKB_DLECOUNT(skb) =
				isdn_tty_countDLE(skb->data, skb->len);
		}
	}
#endif
#endif
	/* Try to deliver directly via tty-flip-buf if queue is empty */
	save_flags(flags);
	cli();
	if (skb_queue_empty(&dev->drv[di]->rpqueue[channel]))
		if (isdn_tty_try_read(info, skb)) {
			restore_flags(flags);
			return 1;
		}
	/* Direct deliver failed or queue wasn't empty.
	 * Queue up for later dequeueing via timer-irq.
	 */
	__skb_queue_tail(&dev->drv[di]->rpqueue[channel], skb);
	dev->drv[di]->rcvcount[channel] +=
		(skb->len
#ifdef CONFIG_ISDN_AUDIO
		 + ISDN_AUDIO_SKB_DLECOUNT(skb)
#endif
			);
	restore_flags(flags);
	/* Schedule dequeuing */
	if ((dev->modempoll) && (info->rcvsched))
		isdn_timer_ctrl(ISDN_TIMER_MODEMREAD, 1);
	return 1;
}

void
isdn_tty_cleanup_xmit(modem_info * info)
{
	struct sk_buff *skb;
	unsigned long flags;

	save_flags(flags);
	cli();
	if (skb_queue_len(&info->xmit_queue))
		while ((skb = skb_dequeue(&info->xmit_queue)))
			kfree_skb(skb);
#ifdef CONFIG_ISDN_AUDIO
	if (skb_queue_len(&info->dtmf_queue))
		while ((skb = skb_dequeue(&info->dtmf_queue)))
			kfree_skb(skb);
#endif
	restore_flags(flags);
}

static void
isdn_tty_tint(modem_info * info)
{
	struct sk_buff *skb = skb_dequeue(&info->xmit_queue);
	int len,
	 slen;

	if (!skb)
		return;
	len = skb->len;
	if ((slen = isdn_writebuf_skb_stub(info->isdn_driver,
					   info->isdn_channel, 1, skb)) == len) {
		struct tty_struct *tty = info->tty;
		info->send_outstanding++;
		info->msr &= ~UART_MSR_CTS;
		info->lsr &= ~UART_LSR_TEMT;
		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
		    tty->ldisc.write_wakeup)
			(tty->ldisc.write_wakeup) (tty);
		wake_up_interruptible(&tty->write_wait);
		return;
	}
	if (slen < 0) {
		/* Error: no channel, already shutdown, or wrong parameter */
		dev_kfree_skb(skb);
		return;
	}
	skb_queue_head(&info->xmit_queue, skb);
}

#ifdef CONFIG_ISDN_AUDIO
static int
isdn_tty_countDLE(unsigned char *buf, int len)
{
	int count = 0;

	while (len--)
		if (*buf++ == DLE)
			count++;
	return count;
}

/* This routine is called from within isdn_tty_write() to perform
 * DLE-decoding when sending audio-data.
 */
static int
isdn_tty_handleDLEdown(modem_info * info, atemu * m, int len)
{
	unsigned char *p = &info->xmit_buf[info->xmit_count];
	int count = 0;

	while (len > 0) {
		if (m->lastDLE) {
			m->lastDLE = 0;
			switch (*p) {
				case DLE:
					/* Escape code */
					if (len > 1)
						memmove(p, p + 1, len - 1);
					p--;
					count++;
					break;
				case ETX:
					/* End of data */
					info->vonline |= 4;
					return count;
				case DC4:
					/* Abort RX */
					info->vonline &= ~1;
#ifdef ISDN_DEBUG_MODEM_VOICE
					printk(KERN_DEBUG
					       "DLEdown: got DLE-DC4, send DLE-ETX on ttyI%d\n",
					       info->line);
#endif
					isdn_tty_at_cout("\020\003", info);
					if (!info->vonline) {
#ifdef ISDN_DEBUG_MODEM_VOICE
						printk(KERN_DEBUG
						       "DLEdown: send VCON on ttyI%d\n",
						       info->line);
#endif
						isdn_tty_at_cout("\r\nVCON\r\n", info);
					}
					/* Fall through */
				case 'q':
				case 's':
					/* Silence */
					if (len > 1)
						memmove(p, p + 1, len - 1);
					p--;
					break;
			}
		} else {
			if (*p == DLE)
				m->lastDLE = 1;
			else
				count++;
		}
		p++;
		len--;
	}
	if (len < 0) {
		printk(KERN_WARNING "isdn_tty: len<0 in DLEdown\n");
		return 0;
	}
	return count;
}

/* This routine is called from within isdn_tty_write() when receiving
 * audio-data. It interrupts receiving, if an character other than
 * ^S or ^Q is sent.
 */
static int
isdn_tty_end_vrx(const char *buf, int c, int from_user)
{
	char ch;

	while (c--) {
		if (from_user)
			get_user(ch, buf);
		else
			ch = *buf;
		if ((ch != 0x11) && (ch != 0x13))
			return 1;
		buf++;
	}
	return 0;
}

static int voice_cf[7] =
{0, 0, 4, 3, 2, 0, 0};

#endif                          /* CONFIG_ISDN_AUDIO */

/* isdn_tty_senddown() is called either directly from within isdn_tty_write()
 * or via timer-interrupt from within isdn_tty_modem_xmit(). It pulls
 * outgoing data from the tty's xmit-buffer, handles voice-decompression or
 * T.70 if necessary, and finally queues it up for sending via isdn_tty_tint.
 */
static void
isdn_tty_senddown(modem_info * info)
{
	int buflen;
	int skb_res;
#ifdef CONFIG_ISDN_AUDIO
	int audio_len;
#endif
	struct sk_buff *skb;

#ifdef CONFIG_ISDN_AUDIO
	if (info->vonline & 4) {
		info->vonline &= ~6;
		if (!info->vonline) {
#ifdef ISDN_DEBUG_MODEM_VOICE
			printk(KERN_DEBUG
			       "senddown: send VCON on ttyI%d\n",
			       info->line);
#endif
			isdn_tty_at_cout("\r\nVCON\r\n", info);
		}
	}
#endif
	if (!(buflen = info->xmit_count))
		return;
 	if ((info->emu.mdmreg[REG_CTS] & BIT_CTS) != 0)
		info->msr &= ~UART_MSR_CTS;
	info->lsr &= ~UART_LSR_TEMT;	
	/* info->xmit_count is modified here and in isdn_tty_write().
	 * So we return here if isdn_tty_write() is in the
	 * critical section.
	 */
	atomic_inc(&info->xmit_lock);
	if (!(atomic_dec_and_test(&info->xmit_lock)))