Line data    Source code

       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             : 
      10             : struct 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             : 
      27             : static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
      28             : {
      29           0 :         return ((unsigned char *)b->data) + ofs;
      30             : }
      31             : 
      32             : static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
      33             : {
      34           0 :         return (char *)char_buf_ptr(b, ofs) + b->size;
      35             : }
      36             : 
      37             : struct 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