text: /*
   * Input device TTY line discipline
   *
   * Copyright (c) 1999-2002 Vojtech Pavlik
   *
   * This is a module that converts a tty line into a much simpler
   * 'serial io port' abstraction that the input device drivers use.
   */
  
  /*
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   */
  
  #include <asm/uaccess.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/serio.h>
  #include <linux/tty.h>
  #include <linux/compat.h>
  
  MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  MODULE_DESCRIPTION("Input device TTY line discipline");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_LDISC(N_MOUSE);
  
  #define SERPORT_BUSY	1
  #define SERPORT_ACTIVE	2
  #define SERPORT_DEAD	3
  
  struct serport {
  	struct tty_struct *tty;
  	wait_queue_head_t wait;
  	struct serio *serio;
  	struct serio_device_id id;
  	spinlock_t lock;
  	unsigned long flags;
  };
  
  /*
   * Callback functions from the serio code.
   */
  
  static int serport_serio_write(struct serio *serio, unsigned char data)
  {
  	struct serport *serport = serio->port_data;
  	return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
  }
  
  static int serport_serio_open(struct serio *serio)
  {
  	struct serport *serport = serio->port_data;
  	unsigned long flags;
  
  	spin_lock_irqsave(&serport->lock, flags);
  	set_bit(SERPORT_ACTIVE, &serport->flags);
  	spin_unlock_irqrestore(&serport->lock, flags);
  
  	return 0;
  }
  
  
  static void serport_serio_close(struct serio *serio)
  {
  	struct serport *serport = serio->port_data;
  	unsigned long flags;
  
  	spin_lock_irqsave(&serport->lock, flags);
  	clear_bit(SERPORT_ACTIVE, &serport->flags);
  	spin_unlock_irqrestore(&serport->lock, flags);
  }
  
  /*
   * serport_ldisc_open() is the routine that is called upon setting our line
   * discipline on a tty. It prepares the serio struct.
   */
  
  static int serport_ldisc_open(struct tty_struct *tty)
  {
  	struct serport *serport;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	serport = kzalloc(sizeof(struct serport), GFP_KERNEL);
  	if (!serport)
  		return -ENOMEM;
  
  	serport->tty = tty;
  	spin_lock_init(&serport->lock);
  	init_waitqueue_head(&serport->wait);
  
  	tty->disc_data = serport;
  	tty->receive_room = 256;
  	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  
  	return 0;
  }
  
  /*
   * serport_ldisc_close() is the opposite of serport_ldisc_open()
   */
  
  static void serport_ldisc_close(struct tty_struct *tty)
  {
  	struct serport *serport = (struct serport *) tty->disc_data;
  
  	kfree(serport);
  }
  
  /*
   * serport_ldisc_receive() is called by the low level tty driver when characters
   * are ready for us. We forward the characters and flags, one by one to the
   * 'interrupt' routine.
   */
  
  static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
  {
  	struct serport *serport = (struct serport*) tty->disc_data;
  	unsigned long flags;
  	unsigned int ch_flags = 0;
  	int i;
  
  	spin_lock_irqsave(&serport->lock, flags);
  
  	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
  		goto out;
  
  	for (i = 0; i < count; i++) {
  		if (fp) {
  			switch (fp[i]) {
  			case TTY_FRAME:
  				ch_flags = SERIO_FRAME;
  				break;
  
  			case TTY_PARITY:
  				ch_flags = SERIO_PARITY;
  				break;
  
  			default:
  				ch_flags = 0;
  				break;
  			}
  		}
  
  		serio_interrupt(serport->serio, cp[i], ch_flags);
  	}
  
  out:
  	spin_unlock_irqrestore(&serport->lock, flags);
  }
  
  /*
   * serport_ldisc_read() just waits indefinitely if everything goes well.
   * However, when the serio driver closes the serio port, it finishes,
   * returning 0 characters.
   */
  
  static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
  {
  	struct serport *serport = (struct serport*) tty->disc_data;
  	struct serio *serio;
  
  	if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
  		return -EBUSY;
  
  	serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
  	if (!serio)
  		return -ENOMEM;
  
  	strlcpy(serio->name, "Serial port", sizeof(serio->name));
  	snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty));
  	serio->id = serport->id;
  	serio->id.type = SERIO_RS232;
  	serio->write = serport_serio_write;
  	serio->open = serport_serio_open;
  	serio->close = serport_serio_close;
  	serio->port_data = serport;
  	serio->dev.parent = tty->dev;
  
  	serio_register_port(serport->serio);
  	printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty));
  
  	wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
  	serio_unregister_port(serport->serio);
  	serport->serio = NULL;
  
  	clear_bit(SERPORT_DEAD, &serport->flags);
  	clear_bit(SERPORT_BUSY, &serport->flags);
  
  	return 0;
  }
  
  static void serport_set_type(struct tty_struct *tty, unsigned long type)
  {
  	struct serport *serport = tty->disc_data;
  
  	serport->id.proto = type & 0x000000ff;
  	serport->id.id    = (type & 0x0000ff00) >> 8;
  	serport->id.extra = (type & 0x00ff0000) >> 16;
  }
  
  /*
   * serport_ldisc_ioctl() allows to set the port protocol, and device ID
   */
  
  static int serport_ldisc_ioctl(struct tty_struct *tty, struct file *file,
  			       unsigned int cmd, unsigned long arg)
  {
  	if (cmd == SPIOCSTYPE) {
  		unsigned long type;
  
  		if (get_user(type, (unsigned long __user *) arg))
  			return -EFAULT;
  
  		serport_set_type(tty, type);
  		return 0;
  	}
  
  	return -EINVAL;
  }
  
  #ifdef CONFIG_COMPAT
  #define COMPAT_SPIOCSTYPE	_IOW('q', 0x01, compat_ulong_t)
  static long serport_ldisc_compat_ioctl(struct tty_struct *tty,
  				       struct file *file,
  				       unsigned int cmd, unsigned long arg)
  {
  	if (cmd == COMPAT_SPIOCSTYPE) {
  		void __user *uarg = compat_ptr(arg);
  		compat_ulong_t compat_type;
  
  		if (get_user(compat_type, (compat_ulong_t __user *)uarg))
  			return -EFAULT;
  
  		serport_set_type(tty, compat_type);
  		return 0;
  	}
  
  	return -EINVAL;
  }
  #endif
  
  static int serport_ldisc_hangup(struct tty_struct *tty)
  {
  	struct serport *serport = (struct serport *) tty->disc_data;
  	unsigned long flags;
  
  	spin_lock_irqsave(&serport->lock, flags);
  	set_bit(SERPORT_DEAD, &serport->flags);
  	spin_unlock_irqrestore(&serport->lock, flags);
  
  	wake_up_interruptible(&serport->wait);
  	return 0;
  }
  
  static void serport_ldisc_write_wakeup(struct tty_struct * tty)
  {
  	struct serport *serport = (struct serport *) tty->disc_data;
  	unsigned long flags;
  
  	spin_lock_irqsave(&serport->lock, flags);
  	if (test_bit(SERPORT_ACTIVE, &serport->flags))
  		serio_drv_write_wakeup(serport->serio);
  	spin_unlock_irqrestore(&serport->lock, flags);
  }
  
  /*
   * The line discipline structure.
   */
  
  static struct tty_ldisc_ops serport_ldisc = {
  	.owner =	THIS_MODULE,
  	.name =		"input",
  	.open =		serport_ldisc_open,
  	.close =	serport_ldisc_close,
  	.read =		serport_ldisc_read,
  	.ioctl =	serport_ldisc_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl =	serport_ldisc_compat_ioctl,
  #endif
  	.receive_buf =	serport_ldisc_receive,
  	.hangup =	serport_ldisc_hangup,
  	.write_wakeup =	serport_ldisc_write_wakeup
  };
  
  /*
   * The functions for insering/removing us as a module.
   */
  
  static int __init serport_init(void)
  {
  	int retval;
  	retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
  	if (retval)
  		printk(KERN_ERR "serport.c: Error registering line discipline.\n");
  
  	return  retval;
  }
  
  static void __exit serport_exit(void)
  {
  	tty_unregister_ldisc(N_MOUSE);
  }
  
  module_init(serport_init);
  module_exit(serport_exit);
  