drivers/char/tty_port.c

   1 /*
   2  * Tty port functions
   3  */
   4
   5 #include <linux/types.h>
   6 #include <linux/errno.h>
   7 #include <linux/tty.h>
   8 #include <linux/tty_driver.h>
   9 #include <linux/tty_flip.h>
  10 #include <linux/timer.h>
  11 #include <linux/string.h>
  12 #include <linux/slab.h>
  13 #include <linux/sched.h>
  14 #include <linux/init.h>
  15 #include <linux/wait.h>
  16 #include <linux/bitops.h>
  17 #include <linux/delay.h>
  18 #include <linux/module.h>
  19
  20 void tty_port_init(struct tty_port *port)
  21 {
  22         memset(port, 0, sizeof(*port));
  23         init_waitqueue_head(&port->open_wait);
  24         init_waitqueue_head(&port->close_wait);
  25         mutex_init(&port->mutex);
  26         spin_lock_init(&port->lock);
  27         port->close_delay = (50 * HZ) / 100;
  28         port->closing_wait = (3000 * HZ) / 100;
  29 }
  30 EXPORT_SYMBOL(tty_port_init);
  31
  32 int tty_port_alloc_xmit_buf(struct tty_port *port)
  33 {
  34         /* We may sleep in get_zeroed_page() */
  35         mutex_lock(&port->mutex);
  36         if (port->xmit_buf == NULL)
  37                 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
  38         mutex_unlock(&port->mutex);
  39         if (port->xmit_buf == NULL)
  40                 return -ENOMEM;
  41         return 0;
  42 }
  43 EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
  44
  45 void tty_port_free_xmit_buf(struct tty_port *port)
  46 {
  47         mutex_lock(&port->mutex);
  48         if (port->xmit_buf != NULL) {
  49                 free_page((unsigned long)port->xmit_buf);
  50                 port->xmit_buf = NULL;
  51         }
  52         mutex_unlock(&port->mutex);
  53 }
  54 EXPORT_SYMBOL(tty_port_free_xmit_buf);
  55
  56
  57 /**
  58  *      tty_port_tty_get        -       get a tty reference
  59  *      @port: tty port
  60  *
  61  *      Return a refcount protected tty instance or NULL if the port is not
  62  *      associated with a tty (eg due to close or hangup)
  63  */
  64
  65 struct tty_struct *tty_port_tty_get(struct tty_port *port)
  66 {
  67         unsigned long flags;
  68         struct tty_struct *tty;
  69
  70         spin_lock_irqsave(&port->lock, flags);
  71         tty = tty_kref_get(port->tty);
  72         spin_unlock_irqrestore(&port->lock, flags);
  73         return tty;
  74 }
  75 EXPORT_SYMBOL(tty_port_tty_get);
  76
  77 /**
  78  *      tty_port_tty_set        -       set the tty of a port
  79  *      @port: tty port
  80  *      @tty: the tty
  81  *
  82  *      Associate the port and tty pair. Manages any internal refcounts.
  83  *      Pass NULL to deassociate a port
  84  */
  85
  86 void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
  87 {
  88         unsigned long flags;
  89
  90         spin_lock_irqsave(&port->lock, flags);
  91         if (port->tty)
  92                 tty_kref_put(port->tty);
  93         port->tty = tty_kref_get(tty);
  94         spin_unlock_irqrestore(&port->lock, flags);
  95 }
  96 EXPORT_SYMBOL(tty_port_tty_set);
  97
  98 /**
  99  *      tty_port_carrier_raised -       carrier raised check
 100  *      @port: tty port
 101  *
 102  *      Wrapper for the carrier detect logic. For the moment this is used
 103  *      to hide some internal details. This will eventually become entirely
 104  *      internal to the tty port.
 105  */
 106
 107 int tty_port_carrier_raised(struct tty_port *port)
 108 {
 109         if (port->ops->carrier_raised == NULL)
 110                 return 1;
 111         return port->ops->carrier_raised(port);
 112 }
 113 EXPORT_SYMBOL(tty_port_carrier_raised);