ctctty.c

linux-2.6.15.6

/*
 * $Id: ctctty.c,v 1.29 2005/04/05 08:50:44 mschwide Exp $
 *
 * CTC / ESCON network driver, tty interface.
 *
 * Copyright (C) 2001 IBM Deutschland Entwicklung GmbH, IBM Corporation
 * Author(s): Fritz Elfert ([e-mail], [e-mail])
 *
 * 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.
 *
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/serial_reg.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <linux/devfs_fs_kernel.h>
#include "ctctty.h"
#include "ctcdbug.h"

#define CTC_TTY_MAJOR       43
#define CTC_TTY_MAX_DEVICES 64

#define CTC_ASYNC_MAGIC          0x49344C01 /* for paranoia-checking        */
#define CTC_ASYNC_INITIALIZED    0x80000000 /* port was initialized         */
#define CTC_ASYNC_NORMAL_ACTIVE  0x20000000 /* Normal device active         */
#define CTC_ASYNC_CLOSING        0x08000000 /* Serial port is closing       */
#define CTC_ASYNC_CTS_FLOW       0x04000000 /* Do CTS flow control          */
#define CTC_ASYNC_CHECK_CD       0x02000000 /* i.e., CLOCAL                 */
#define CTC_ASYNC_HUP_NOTIFY         0x0001 /* Notify tty on hangups/closes */
#define CTC_ASYNC_NETDEV_OPEN        0x0002 /* Underlying netdev is open    */
#define CTC_ASYNC_TX_LINESTAT        0x0004 /* Must send line status        */
#define CTC_ASYNC_SPLIT_TERMIOS      0x0008 /* Sep. termios for dialin/out  */
#define CTC_TTY_XMIT_SIZE              1024 /* Default bufsize for write    */
#define CTC_SERIAL_XMIT_MAX            4000 /* Maximum bufsize for write    */

/* Private data (similar to async_struct in <linux/serial.h>) */
typedef struct {
  int			magic;
  int			flags;		 /* defined in tty.h               */
  int			mcr;		 /* Modem control register         */
  int                   msr;             /* Modem status register          */
  int                   lsr;             /* Line status register           */
  int			line;
  int			count;		 /* # of fd on device              */
  int			blocked_open;	 /* # of blocked opens             */
  struct net_device     *netdev;
  struct sk_buff_head   tx_queue;        /* transmit queue                 */
  struct sk_buff_head   rx_queue;        /* receive queue                  */
  struct tty_struct 	*tty;            /* Pointer to corresponding tty   */
  wait_queue_head_t	open_wait;
  wait_queue_head_t	close_wait;
  struct semaphore      write_sem;
  struct tasklet_struct tasklet;
  struct timer_list     stoptimer;
} ctc_tty_info;

/* Description of one CTC-tty */
typedef struct {
  struct tty_driver  *ctc_tty_device;		   /* tty-device             */
  ctc_tty_info       info[CTC_TTY_MAX_DEVICES];	   /* Private data           */
} ctc_tty_driver;

static ctc_tty_driver *driver;

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

#define CTC_TTY_NAME "ctctty"

static __u32 ctc_tty_magic = CTC_ASYNC_MAGIC;
static int ctc_tty_shuttingdown = 0;

static spinlock_t ctc_tty_lock;

/* ctc_tty_try_read() is called from within ctc_tty_rcv_skb()
 * to stuff incoming data directly into a tty's flip-buffer. If the
 * flip buffer is full, the packet gets queued up.
 *
 * Return:
 *  1 = Success
 *  0 = Failure, data has to be buffered and later processed by
 *      ctc_tty_readmodem().
 */
static int
ctc_tty_try_read(ctc_tty_info * info, struct sk_buff *skb)
{
	int c;
	int len;
	struct tty_struct *tty;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if ((tty = info->tty)) {
		if (info->mcr & UART_MCR_RTS) {
			c = TTY_FLIPBUF_SIZE - tty->flip.count;
			len = skb->len;
			if (c >= len) {
				memcpy(tty->flip.char_buf_ptr, skb->data, len);
				memset(tty->flip.flag_buf_ptr, 0, len);
				tty->flip.count += len;
				tty->flip.char_buf_ptr += len;
				tty->flip.flag_buf_ptr += len;
				tty_flip_buffer_push(tty);
				kfree_skb(skb);
				return 1;
			}
		}
	}
	return 0;
}

/* ctc_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.
 */
static int
ctc_tty_readmodem(ctc_tty_info *info)
{
	int ret = 1;
	struct tty_struct *tty;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if ((tty = info->tty)) {
		if (info->mcr & UART_MCR_RTS) {
			int c = TTY_FLIPBUF_SIZE - tty->flip.count;
			struct sk_buff *skb;
			
			if ((c > 0) && (skb = skb_dequeue(&info->rx_queue))) {
				int len = skb->len;
				if (len > c)
					len = c;
				memcpy(tty->flip.char_buf_ptr, skb->data, len);
				skb_pull(skb, len);
				memset(tty->flip.flag_buf_ptr, 0, len);
				tty->flip.count += len;
				tty->flip.char_buf_ptr += len;
				tty->flip.flag_buf_ptr += len;
				tty_flip_buffer_push(tty);
				if (skb->len > 0)
					skb_queue_head(&info->rx_queue, skb);
				else {
					kfree_skb(skb);
					ret = !skb_queue_empty(&info->rx_queue);
				}
			}
		}
	}
	return ret;
}

void
ctc_tty_setcarrier(struct net_device *netdev, int on)
{
	int i;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if ((!driver) || ctc_tty_shuttingdown)
		return;
	for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
		if (driver->info[i].netdev == netdev) {
			ctc_tty_info *info = &driver->info[i];
			if (on)
				info->msr |= UART_MSR_DCD;
			else
				info->msr &= ~UART_MSR_DCD;
			if ((info->flags & CTC_ASYNC_CHECK_CD) && (!on))
				tty_hangup(info->tty);
		}
}

void
ctc_tty_netif_rx(struct sk_buff *skb)
{
	int i;
	ctc_tty_info *info = NULL;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if (!skb)
		return;
	if ((!skb->dev) || (!driver) || ctc_tty_shuttingdown) {
		dev_kfree_skb(skb);
		return;
	}
	for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
		if (driver->info[i].netdev == skb->dev) {
			info = &driver->info[i];
			break;
		}
	if (!info) {
		dev_kfree_skb(skb);
		return;
	}
	if (skb->len < 6) {
		dev_kfree_skb(skb);
		return;
	}
	if (memcmp(skb->data, &ctc_tty_magic, sizeof(__u32))) {
		dev_kfree_skb(skb);
		return;
	}
	skb_pull(skb, sizeof(__u32));

	i = *((int *)skb->data);
	skb_pull(skb, sizeof(info->mcr));
	if (i & UART_MCR_RTS) {
		info->msr |= UART_MSR_CTS;
		if (info->flags & CTC_ASYNC_CTS_FLOW)
			info->tty->hw_stopped = 0;
	} else {
		info->msr &= ~UART_MSR_CTS;
		if (info->flags & CTC_ASYNC_CTS_FLOW)
			info->tty->hw_stopped = 1;
	}
	if (i & UART_MCR_DTR)
		info->msr |= UART_MSR_DSR;
	else
		info->msr &= ~UART_MSR_DSR;
	if (skb->len <= 0) {
		kfree_skb(skb);
		return;
	}
	/* Try to deliver directly via tty-flip-buf if queue is empty */
	if (skb_queue_empty(&info->rx_queue))
		if (ctc_tty_try_read(info, skb))
			return;
	/* Direct deliver failed or queue wasn't empty.
	 * Queue up for later dequeueing via timer-irq.
	 */
	skb_queue_tail(&info->rx_queue, skb);
	/* Schedule dequeuing */
	tasklet_schedule(&info->tasklet);
}

static int
ctc_tty_tint(ctc_tty_info * info)
{
	struct sk_buff *skb = skb_dequeue(&info->tx_queue);
	int stopped = (info->tty->hw_stopped || info->tty->stopped);
	int wake = 1;
	int rc;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (!info->netdev) {
		if (skb)
			kfree_skb(skb);
		return 0;
	}
	if (info->flags & CTC_ASYNC_TX_LINESTAT) {
		int skb_res = info->netdev->hard_header_len +
			sizeof(info->mcr) + sizeof(__u32);
		/* If we must update line status,
		 * create an empty dummy skb and insert it.
		 */
		if (skb)
			skb_queue_head(&info->tx_queue, skb);

		skb = dev_alloc_skb(skb_res);
		if (!skb) {
			printk(KERN_WARNING
			       "ctc_tty: Out of memory in %s%d tint\n",
			       CTC_TTY_NAME, info->line);
			return 1;
		}
		skb_reserve(skb, skb_res);
		stopped = 0;
		wake = 0;
	}
	if (!skb)
		return 0;
	if (stopped) {
		skb_queue_head(&info->tx_queue, skb);
		return 1;
	}
#if 0
	if (skb->len > 0)
		printk(KERN_DEBUG "tint: %d %02x\n", skb->len, *(skb->data));
	else
		printk(KERN_DEBUG "tint: %d STAT\n", skb->len);
#endif
	memcpy(skb_push(skb, sizeof(info->mcr)), &info->mcr, sizeof(info->mcr));
	memcpy(skb_push(skb, sizeof(__u32)), &ctc_tty_magic, sizeof(__u32));
	rc = info->netdev->hard_start_xmit(skb, info->netdev);
	if (rc) {
		skb_pull(skb, sizeof(info->mcr) + sizeof(__u32));
		if (skb->len > 0)
			skb_queue_head(&info->tx_queue, skb);
		else
			kfree_skb(skb);
	} else {
		struct tty_struct *tty = info->tty;

		info->flags &= ~CTC_ASYNC_TX_LINESTAT;
		if (tty) {
			tty_wakeup(tty);
		}
	}
	return (skb_queue_empty(&info->tx_queue) ? 0 : 1);
}

/************************************************************
 *
 * Modem-functions
 *
 * mostly "stolen" from original Linux-serial.c and friends.
 *
 ************************************************************/

static inline int
ctc_tty_paranoia_check(ctc_tty_info * info, char *name, const char *routine)
{
#ifdef MODEM_PARANOIA_CHECK
	if (!info) {
		printk(KERN_WARNING "ctc_tty: null info_struct for %s in %s\n",
		       name, routine);
		return 1;
	}
	if (info->magic != CTC_ASYNC_MAGIC) {
		printk(KERN_WARNING "ctc_tty: bad magic for info struct %s in %s\n",
		       name, routine);
		return 1;
	}
#endif
	return 0;
}

static void
ctc_tty_inject(ctc_tty_info *info, char c)
{
	int skb_res;
	struct sk_buff *skb;
	
	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_shuttingdown)
		return;
	skb_res = info->netdev->hard_header_len + sizeof(info->mcr) +
		sizeof(__u32) + 1;
	skb = dev_alloc_skb(skb_res);
	if (!skb) {
		printk(KERN_WARNING
		       "ctc_tty: Out of memory in %s%d tx_inject\n",
		       CTC_TTY_NAME, info->line);
		return;
	}
	skb_reserve(skb, skb_res);
	*(skb_put(skb, 1)) = c;
	skb_queue_head(&info->tx_queue, skb);
	tasklet_schedule(&info->tasklet);
}

static void
ctc_tty_transmit_status(ctc_tty_info *info)
{
	DBF_TEXT(trace, 5, __FUNCTION__);
	if (ctc_tty_shuttingdown)
		return;
	info->flags |= CTC_ASYNC_TX_LINESTAT;
	tasklet_schedule(&info->tasklet);
}

static void
ctc_tty_change_speed(ctc_tty_info * info)
{
	unsigned int cflag;
	unsigned int quot;
	int i;

	DBF_TEXT(trace, 3, __FUNCTION__);
	if (!info->tty || !info->tty->termios)
		return;
	cflag = info->tty->termios->c_cflag;

	quot = i = cflag & CBAUD;
	if (i & CBAUDEX) {
		i &= ~CBAUDEX;
		if (i < 1 || i > 2)
			info->tty->termios->c_cflag &= ~CBAUDEX;
		else
			i += 15;
	}
	if (quot) {
		info->mcr |= UART_MCR_DTR;
		info->mcr |= UART_MCR_RTS;
		ctc_tty_transmit_status(info);
	} else {
		info->mcr &= ~UART_MCR_DTR;
		info->mcr &= ~UART_MCR_RTS;
		ctc_tty_transmit_status(info);
		return;
	}

	/* CTS flow control flag and modem status interrupts */
	if (cflag & CRTSCTS) {
		info->flags |= CTC_ASYNC_CTS_FLOW;
	} else
		info->flags &= ~CTC_ASYNC_CTS_FLOW;
	if (cflag & CLOCAL)
		info->flags &= ~CTC_ASYNC_CHECK_CD;
	else {
		info->flags |= CTC_ASYNC_CHECK_CD;
	}
}

static int
ctc_tty_startup(ctc_tty_info * info)
{
	DBF_TEXT(trace, 3, __FUNCTION__);
	if (info->flags & CTC_ASYNC_INITIALIZED)
		return 0;
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "starting up %s%d ...\n", CTC_TTY_NAME, info->line);