/*

   * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)

   * Licensed under the GPL
   */

  #include "linux/completion.h"

  #include "linux/interrupt.h"

  #include "linux/list.h"

  #include "linux/mutex.h"

  #include "linux/slab.h"

  #include "linux/workqueue.h"

  #include "asm/atomic.h"

  #include "init.h"

  #include "irq_kern.h"

  #include "os.h"

  #include "port.h"

  
  struct port_list {
  	struct list_head list;
  	atomic_t wait_count;
  	int has_connection;
  	struct completion done;
  	int port;
  	int fd;
  	spinlock_t lock;
  	struct list_head pending;
  	struct list_head connections;
  };
  
  struct port_dev {
  	struct port_list *port;
  	int helper_pid;
  	int telnetd_pid;
  };
  
  struct connection {
  	struct list_head list;
  	int fd;
  	int helper_pid;
  	int socket[2];
  	int telnetd_pid;
  	struct port_list *port;
  };

  static irqreturn_t pipe_interrupt(int irq, void *data)

  {
  	struct connection *conn = data;
  	int fd;
  
  	fd = os_rcv_fd(conn->socket[0], &conn->helper_pid);

  	if (fd < 0) {
  		if (fd == -EAGAIN)

  			return IRQ_NONE;

  		printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d
  ",

  		       -fd);
  		os_close_file(conn->fd);
  	}
  
  	list_del(&conn->list);
  
  	conn->fd = fd;
  	list_add(&conn->list, &conn->port->connections);
  
  	complete(&conn->port->done);

  	return IRQ_HANDLED;

  }
  
  #define NO_WAITER_MSG \
      "****
  " \
      "There are currently no UML consoles waiting for port connections.
  " \
      "Either disconnect from one to make it available or activate some more
  " \
      "by enabling more consoles in the UML /etc/inittab.
  " \
      "****
  "
  
  static int port_accept(struct port_list *port)
  {
  	struct connection *conn;

  	int fd, socket[2], pid;

  
  	fd = port_connection(port->fd, socket, &pid);

  	if (fd < 0) {
  		if (fd != -EAGAIN)

  			printk(KERN_ERR "port_accept : port_connection "
  			       "returned %d
  ", -fd);
  		goto out;
  	}
  
  	conn = kmalloc(sizeof(*conn), GFP_ATOMIC);

  	if (conn == NULL) {

  		printk(KERN_ERR "port_accept : failed to allocate "
  		       "connection
  ");
  		goto out_close;
  	}

  	*conn = ((struct connection)

  		{ .list 	= LIST_HEAD_INIT(conn->list),
  		  .fd 		= fd,
  		  .socket  	= { socket[0], socket[1] },
  		  .telnetd_pid 	= pid,
  		  .port 	= port });

  	if (um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt,

  			  IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,

  			  "telnetd", conn)) {

  		printk(KERN_ERR "port_accept : failed to get IRQ for "
  		       "telnetd
  ");
  		goto out_free;
  	}

  	if (atomic_read(&port->wait_count) == 0) {

  		os_write_file(fd, NO_WAITER_MSG, sizeof(NO_WAITER_MSG));

  		printk(KERN_ERR "No one waiting for port
  ");

  	}
  	list_add(&conn->list, &port->pending);

  	return 1;

  
   out_free:
  	kfree(conn);
   out_close:
  	os_close_file(fd);

  	os_kill_process(pid, 1);

   out:

  	return 0;

  }

  static DEFINE_MUTEX(ports_mutex);

  static LIST_HEAD(ports);

  static void port_work_proc(struct work_struct *unused)

  {
  	struct port_list *port;
  	struct list_head *ele;
  	unsigned long flags;
  
  	local_irq_save(flags);

  	list_for_each(ele, &ports) {

  		port = list_entry(ele, struct port_list, list);

  		if (!port->has_connection)

  			continue;

  		reactivate_fd(port->fd, ACCEPT_IRQ);

  		while (port_accept(port))
  			;

  		port->has_connection = 0;
  	}
  	local_irq_restore(flags);
  }

  DECLARE_WORK(port_work, port_work_proc);

  static irqreturn_t port_interrupt(int irq, void *data)

  {
  	struct port_list *port = data;
  
  	port->has_connection = 1;
  	schedule_work(&port_work);

  	return IRQ_HANDLED;
  }

  
  void *port_data(int port_num)
  {
  	struct list_head *ele;
  	struct port_list *port;
  	struct port_dev *dev = NULL;
  	int fd;

  	mutex_lock(&ports_mutex);

  	list_for_each(ele, &ports) {

  		port = list_entry(ele, struct port_list, list);

  		if (port->port == port_num)
  			goto found;

  	}
  	port = kmalloc(sizeof(struct port_list), GFP_KERNEL);

  	if (port == NULL) {

  		printk(KERN_ERR "Allocation of port list failed
  ");
  		goto out;
  	}
  
  	fd = port_listen_fd(port_num);

  	if (fd < 0) {

  		printk(KERN_ERR "binding to port %d failed, errno = %d
  ",
  		       port_num, -fd);
  		goto out_free;
  	}

  
  	if (um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt,

  			  IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,

  			  "port", port)) {

  		printk(KERN_ERR "Failed to get IRQ for port %d
  ", port_num);
  		goto out_close;
  	}

  	*port = ((struct port_list)

  		{ .list 	 	= LIST_HEAD_INIT(port->list),
  		  .wait_count		= ATOMIC_INIT(0),
  		  .has_connection 	= 0,
  		  .port 	 	= port_num,
  		  .fd  			= fd,
  		  .pending 		= LIST_HEAD_INIT(port->pending),
  		  .connections 		= LIST_HEAD_INIT(port->connections) });
  	spin_lock_init(&port->lock);
  	init_completion(&port->done);
  	list_add(&port->list, &ports);
  
   found:
  	dev = kmalloc(sizeof(struct port_dev), GFP_KERNEL);

  	if (dev == NULL) {

  		printk(KERN_ERR "Allocation of port device entry failed
  ");
  		goto out;
  	}
  
  	*dev = ((struct port_dev) { .port  		= port,
  				    .helper_pid  	= -1,
  				    .telnetd_pid  	= -1 });
  	goto out;

   out_close:
  	os_close_file(fd);

   out_free:
  	kfree(port);

   out:

  	mutex_unlock(&ports_mutex);

  	return dev;

  }
  
  int port_wait(void *data)
  {
  	struct port_dev *dev = data;
  	struct connection *conn;
  	struct port_list *port = dev->port;
  	int fd;

  	atomic_inc(&port->wait_count);

  	while (1) {

  		fd = -ERESTARTSYS;

  		if (wait_for_completion_interruptible(&port->done))

  			goto out;

  
  		spin_lock(&port->lock);

  		conn = list_entry(port->connections.next, struct connection,

  				  list);
  		list_del(&conn->list);
  		spin_unlock(&port->lock);
  
  		os_shutdown_socket(conn->socket[0], 1, 1);
  		os_close_file(conn->socket[0]);
  		os_shutdown_socket(conn->socket[1], 1, 1);

  		os_close_file(conn->socket[1]);

  
  		/* This is done here because freeing an IRQ can't be done
  		 * within the IRQ handler.  So, pipe_interrupt always ups
  		 * the semaphore regardless of whether it got a successful

  		 * connection.  Then we loop here throwing out failed

  		 * connections until a good one is found.
  		 */

  		free_irq(TELNETD_IRQ, conn);

  		if (conn->fd >= 0)
  			break;

  		os_close_file(conn->fd);
  		kfree(conn);
  	}
  
  	fd = conn->fd;
  	dev->helper_pid = conn->helper_pid;
  	dev->telnetd_pid = conn->telnetd_pid;
  	kfree(conn);
   out:
  	atomic_dec(&port->wait_count);
  	return fd;
  }
  
  void port_remove_dev(void *d)
  {
  	struct port_dev *dev = d;

  	if (dev->helper_pid != -1)

  		os_kill_process(dev->helper_pid, 0);

  	if (dev->telnetd_pid != -1)

  		os_kill_process(dev->telnetd_pid, 1);
  	dev->helper_pid = -1;
  	dev->telnetd_pid = -1;
  }
  
  void port_kern_free(void *d)
  {
  	struct port_dev *dev = d;
  
  	port_remove_dev(dev);
  	kfree(dev);
  }
  
  static void free_port(void)
  {
  	struct list_head *ele;
  	struct port_list *port;

  	list_for_each(ele, &ports) {

  		port = list_entry(ele, struct port_list, list);
  		free_irq_by_fd(port->fd);
  		os_close_file(port->fd);
  	}
  }
  
  __uml_exitcall(free_port);