linux-imx

// SPDX-License-Identifier: GPL-2.0

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/kmod.h>

#include <linux/sched.h>

#include <linux/interrupt.h>

#include <linux/tty.h>

#include <linux/tty_driver.h>

#include <linux/file.h>

#include <linux/mm.h>

#include <linux/string.h>

#include <linux/slab.h>

#include <linux/poll.h>

#include <linux/proc_fs.h>

#include <linux/module.h>

#include <linux/device.h>

#include <linux/wait.h>

#include <linux/bitops.h>

#include <linux/seq_file.h>

#include <linux/uaccess.h>

#include <linux/ratelimit.h>

​

#undef LDISC_DEBUG_HANGUP

​

#ifdef LDISC_DEBUG_HANGUP

#define tty_ldisc_debug(tty, f, args...)    tty_debug(tty, f, ##args)

#else

#define tty_ldisc_debug(tty, f, args...)

#endif

​

/* lockdep nested classes for tty->ldisc_sem */

enum {

    LDISC_SEM_NORMAL,

    LDISC_SEM_OTHER,

};

​

​

/*

 *  This guards the refcounted line discipline lists. The lock

 *  must be taken with irqs off because there are hangup path

 *  callers who will do ldisc lookups and cannot sleep.

 */

​

static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock);

/* Line disc dispatch table */

static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];

​

/**

 *  tty_register_ldisc  -   install a line discipline

 *  @disc: ldisc number

 *  @new_ldisc: pointer to the ldisc object

 *

 *  Installs a new line discipline into the kernel. The discipline

 *  is set up as unreferenced and then made available to the kernel

 *  from this point onwards.

 *

 *  Locking:

 *      takes tty_ldiscs_lock to guard against ldisc races

 */

​

int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc)

{

    unsigned long flags;

    int ret = 0;

​

    if (disc < N_TTY || disc >= NR_LDISCS)

        return -EINVAL;

​

    raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);

    tty_ldiscs[disc] = new_ldisc;

    new_ldisc->num = disc;

    new_ldisc->refcount = 0;

    raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);

​

    return ret;

}

EXPORT_SYMBOL(tty_register_ldisc);

​

/**

 *  tty_unregister_ldisc    -   unload a line discipline

 *  @disc: ldisc number

 *  @new_ldisc: pointer to the ldisc object

 *

 *  Remove a line discipline from the kernel providing it is not

 *  currently in use.

 *

 *  Locking:

 *      takes tty_ldiscs_lock to guard against ldisc races

 */

​

int tty_unregister_ldisc(int disc)

{