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	unsigned int used;
16	unsigned int size;
17	unsigned int commit;
18	unsigned int lookahead;		/* Lazy update on recv, can become less than "read" */
19	unsigned int read;
20	bool flags;
21	/* Data points here */
22	u8 data[] __aligned(sizeof(unsigned long));
23};
24
25static inline u8 *char_buf_ptr(struct tty_buffer *b, unsigned int ofs)
26{
27	return b->data + ofs;
28}
29
30static inline u8 *flag_buf_ptr(struct tty_buffer *b, unsigned int ofs)
31{
32	return char_buf_ptr(b, ofs) + b->size;
33}
34
35struct tty_bufhead {
36	struct tty_buffer *head;	/* Queue head */
37	struct work_struct work;
38	struct mutex	   lock;
39	atomic_t	   priority;
40	struct tty_buffer sentinel;
41	struct llist_head free;		/* Free queue head */
42	atomic_t	   mem_used;    /* In-use buffers excluding free list */
43	int		   mem_limit;
44	struct tty_buffer *tail;	/* Active buffer */
45};
46
47/*
48 * When a break, frame error, or parity error happens, these codes are
49 * stuffed into the flags buffer.
50 */
51#define TTY_NORMAL	0
52#define TTY_BREAK	1
53#define TTY_FRAME	2
54#define TTY_PARITY	3
55#define TTY_OVERRUN	4
56
57#endif
58