LXR linux/include/linux/tty

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_TTY_BUFFER_H
   3#define _LINUX_TTY_BUFFER_H
   4
   5#include <linux/atomic.h>
   6#include <linux/llist.h>
   7#include <linux/mutex.h>
   8#include <linux/workqueue.h>
   9
  10struct tty_buffer {
  11        union {
  12                struct tty_buffer *next;
  13                struct llist_node free;
  14        };
  15        int used;
  16        int size;
  17        int commit;
  18        int read;
  19        int flags;
  20        /* Data points here */
  21        unsigned long data[];
  22};
  23
  24/* Values for .flags field of tty_buffer */
  25#define TTYB_NORMAL     1       /* buffer has no flags buffer */
  26
  27static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
  28{
  29        return ((unsigned char *)b->data) + ofs;
  30}
  31
  32static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
  33{
  34        return (char *)char_buf_ptr(b, ofs) + b->size;
  35}
  36
  37struct tty_bufhead {
  38        struct tty_buffer *head;        /* Queue head */
  39        struct work_struct work;
  40        struct mutex       lock;
  41        atomic_t           priority;
  42        struct tty_buffer sentinel;
  43        struct llist_head free;         /* Free queue head */
  44        atomic_t           mem_used;    /* In-use buffers excluding free list */
  45        int                mem_limit;
  46        struct tty_buffer *tail;        /* Active buffer */
  47};
  48
  49/*
  50 * When a break, frame error, or parity error happens, these codes are
  51 * stuffed into the flags buffer.
  52 */
  53#define TTY_NORMAL      0
  54#define TTY_BREAK       1
  55#define TTY_FRAME       2
  56#define TTY_PARITY      3
  57#define TTY_OVERRUN     4
  58
  59#endif
  60