mirror of https://gitee.com/openkylin/linux.git
351 lines
8.8 KiB
C
351 lines
8.8 KiB
C
/*
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* Tty port functions
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*/
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/tty.h>
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#include <linux/tty_driver.h>
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#include <linux/tty_flip.h>
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#include <linux/serial.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/wait.h>
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#include <linux/bitops.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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void tty_port_init(struct tty_port *port)
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{
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memset(port, 0, sizeof(*port));
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init_waitqueue_head(&port->open_wait);
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init_waitqueue_head(&port->close_wait);
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mutex_init(&port->mutex);
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spin_lock_init(&port->lock);
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port->close_delay = (50 * HZ) / 100;
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port->closing_wait = (3000 * HZ) / 100;
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}
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EXPORT_SYMBOL(tty_port_init);
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int tty_port_alloc_xmit_buf(struct tty_port *port)
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{
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/* We may sleep in get_zeroed_page() */
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mutex_lock(&port->mutex);
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if (port->xmit_buf == NULL)
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port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
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mutex_unlock(&port->mutex);
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if (port->xmit_buf == NULL)
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return -ENOMEM;
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return 0;
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}
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EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
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void tty_port_free_xmit_buf(struct tty_port *port)
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{
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mutex_lock(&port->mutex);
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if (port->xmit_buf != NULL) {
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free_page((unsigned long)port->xmit_buf);
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port->xmit_buf = NULL;
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}
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mutex_unlock(&port->mutex);
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}
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EXPORT_SYMBOL(tty_port_free_xmit_buf);
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/**
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* tty_port_tty_get - get a tty reference
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* @port: tty port
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*
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* Return a refcount protected tty instance or NULL if the port is not
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* associated with a tty (eg due to close or hangup)
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*/
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struct tty_struct *tty_port_tty_get(struct tty_port *port)
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{
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unsigned long flags;
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struct tty_struct *tty;
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spin_lock_irqsave(&port->lock, flags);
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tty = tty_kref_get(port->tty);
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spin_unlock_irqrestore(&port->lock, flags);
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return tty;
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}
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EXPORT_SYMBOL(tty_port_tty_get);
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/**
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* tty_port_tty_set - set the tty of a port
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* @port: tty port
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* @tty: the tty
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*
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* Associate the port and tty pair. Manages any internal refcounts.
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* Pass NULL to deassociate a port
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*/
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void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
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{
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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if (port->tty)
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tty_kref_put(port->tty);
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port->tty = tty_kref_get(tty);
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spin_unlock_irqrestore(&port->lock, flags);
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}
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EXPORT_SYMBOL(tty_port_tty_set);
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/**
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* tty_port_hangup - hangup helper
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* @port: tty port
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*
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* Perform port level tty hangup flag and count changes. Drop the tty
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* reference.
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*/
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void tty_port_hangup(struct tty_port *port)
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{
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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port->count = 0;
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port->flags &= ~ASYNC_NORMAL_ACTIVE;
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if (port->tty)
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tty_kref_put(port->tty);
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port->tty = NULL;
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spin_unlock_irqrestore(&port->lock, flags);
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wake_up_interruptible(&port->open_wait);
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}
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EXPORT_SYMBOL(tty_port_hangup);
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/**
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* tty_port_carrier_raised - carrier raised check
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* @port: tty port
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*
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* Wrapper for the carrier detect logic. For the moment this is used
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* to hide some internal details. This will eventually become entirely
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* internal to the tty port.
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*/
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int tty_port_carrier_raised(struct tty_port *port)
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{
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if (port->ops->carrier_raised == NULL)
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return 1;
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return port->ops->carrier_raised(port);
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}
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EXPORT_SYMBOL(tty_port_carrier_raised);
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/**
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* tty_port_raise_dtr_rts - Raise DTR/RTS
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* @port: tty port
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*
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* Wrapper for the DTR/RTS raise logic. For the moment this is used
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* to hide some internal details. This will eventually become entirely
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* internal to the tty port.
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*/
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void tty_port_raise_dtr_rts(struct tty_port *port)
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{
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if (port->ops->dtr_rts)
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port->ops->dtr_rts(port, 1);
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}
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EXPORT_SYMBOL(tty_port_raise_dtr_rts);
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/**
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* tty_port_lower_dtr_rts - Lower DTR/RTS
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* @port: tty port
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*
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* Wrapper for the DTR/RTS raise logic. For the moment this is used
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* to hide some internal details. This will eventually become entirely
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* internal to the tty port.
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*/
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void tty_port_lower_dtr_rts(struct tty_port *port)
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{
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if (port->ops->dtr_rts)
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port->ops->dtr_rts(port, 0);
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}
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EXPORT_SYMBOL(tty_port_lower_dtr_rts);
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/**
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* tty_port_block_til_ready - Waiting logic for tty open
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* @port: the tty port being opened
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* @tty: the tty device being bound
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* @filp: the file pointer of the opener
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*
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* Implement the core POSIX/SuS tty behaviour when opening a tty device.
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* Handles:
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* - hangup (both before and during)
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* - non blocking open
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* - rts/dtr/dcd
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* - signals
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* - port flags and counts
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*
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* The passed tty_port must implement the carrier_raised method if it can
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* do carrier detect and the dtr_rts method if it supports software
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* management of these lines. Note that the dtr/rts raise is done each
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* iteration as a hangup may have previously dropped them while we wait.
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*/
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int tty_port_block_til_ready(struct tty_port *port,
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struct tty_struct *tty, struct file *filp)
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{
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int do_clocal = 0, retval;
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unsigned long flags;
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DECLARE_WAITQUEUE(wait, current);
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int cd;
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/* block if port is in the process of being closed */
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if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
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wait_event_interruptible(port->close_wait,
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!(port->flags & ASYNC_CLOSING));
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if (port->flags & ASYNC_HUP_NOTIFY)
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return -EAGAIN;
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else
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return -ERESTARTSYS;
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}
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/* if non-blocking mode is set we can pass directly to open unless
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the port has just hung up or is in another error state */
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if ((filp->f_flags & O_NONBLOCK) ||
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(tty->flags & (1 << TTY_IO_ERROR))) {
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port->flags |= ASYNC_NORMAL_ACTIVE;
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return 0;
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}
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if (C_CLOCAL(tty))
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do_clocal = 1;
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/* Block waiting until we can proceed. We may need to wait for the
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carrier, but we must also wait for any close that is in progress
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before the next open may complete */
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retval = 0;
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/* The port lock protects the port counts */
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spin_lock_irqsave(&port->lock, flags);
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if (!tty_hung_up_p(filp))
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port->count--;
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port->blocked_open++;
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spin_unlock_irqrestore(&port->lock, flags);
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while (1) {
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/* Indicate we are open */
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if (tty->termios->c_cflag & CBAUD)
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tty_port_raise_dtr_rts(port);
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prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
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/* Check for a hangup or uninitialised port. Return accordingly */
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if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
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if (port->flags & ASYNC_HUP_NOTIFY)
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retval = -EAGAIN;
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else
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retval = -ERESTARTSYS;
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break;
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}
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/* Probe the carrier. For devices with no carrier detect this
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will always return true */
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cd = tty_port_carrier_raised(port);
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if (!(port->flags & ASYNC_CLOSING) &&
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(do_clocal || cd))
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break;
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if (signal_pending(current)) {
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retval = -ERESTARTSYS;
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break;
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}
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schedule();
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}
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finish_wait(&port->open_wait, &wait);
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/* Update counts. A parallel hangup will have set count to zero and
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we must not mess that up further */
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spin_lock_irqsave(&port->lock, flags);
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if (!tty_hung_up_p(filp))
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port->count++;
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port->blocked_open--;
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if (retval == 0)
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port->flags |= ASYNC_NORMAL_ACTIVE;
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spin_unlock_irqrestore(&port->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL(tty_port_block_til_ready);
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int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, struct file *filp)
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{
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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if (tty_hung_up_p(filp)) {
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spin_unlock_irqrestore(&port->lock, flags);
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return 0;
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}
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if( tty->count == 1 && port->count != 1) {
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printk(KERN_WARNING
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"tty_port_close_start: tty->count = 1 port count = %d.\n",
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port->count);
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port->count = 1;
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}
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if (--port->count < 0) {
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printk(KERN_WARNING "tty_port_close_start: count = %d\n",
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port->count);
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port->count = 0;
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}
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if (port->count) {
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spin_unlock_irqrestore(&port->lock, flags);
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return 0;
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}
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port->flags |= ASYNC_CLOSING;
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tty->closing = 1;
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spin_unlock_irqrestore(&port->lock, flags);
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/* Don't block on a stalled port, just pull the chain */
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if (tty->flow_stopped)
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tty_driver_flush_buffer(tty);
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if (port->flags & ASYNC_INITIALIZED &&
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port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
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tty_wait_until_sent(tty, port->closing_wait);
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if (port->drain_delay) {
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unsigned int bps = tty_get_baud_rate(tty);
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long timeout;
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if (bps > 1200)
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timeout = max_t(long, (HZ * 10 * port->drain_delay) / bps,
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HZ / 10);
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else
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timeout = 2 * HZ;
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schedule_timeout_interruptible(timeout);
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}
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return 1;
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}
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EXPORT_SYMBOL(tty_port_close_start);
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void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
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{
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unsigned long flags;
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tty_ldisc_flush(tty);
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if (tty->termios->c_cflag & HUPCL)
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tty_port_lower_dtr_rts(port);
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spin_lock_irqsave(&port->lock, flags);
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tty->closing = 0;
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if (port->blocked_open) {
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spin_unlock_irqrestore(&port->lock, flags);
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if (port->close_delay) {
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msleep_interruptible(
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jiffies_to_msecs(port->close_delay));
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}
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spin_lock_irqsave(&port->lock, flags);
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wake_up_interruptible(&port->open_wait);
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}
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port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING);
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wake_up_interruptible(&port->close_wait);
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spin_unlock_irqrestore(&port->lock, flags);
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}
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EXPORT_SYMBOL(tty_port_close_end);
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