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 lookahead;		/* Lazy update on recv, can become less than "read" */
19 	int read;
20 	int flags;
21 	/* Data points here */
22 	unsigned long data[];
23 };
24 
25 /* Values for .flags field of tty_buffer */
26 #define TTYB_NORMAL	1	/* buffer has no flags buffer */
27 
char_buf_ptr(struct tty_buffer * b,int ofs)28 static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
29 {
30 	return ((unsigned char *)b->data) + ofs;
31 }
32 
flag_buf_ptr(struct tty_buffer * b,int ofs)33 static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
34 {
35 	return (char *)char_buf_ptr(b, ofs) + b->size;
36 }
37 
38 struct tty_bufhead {
39 	struct tty_buffer *head;	/* Queue head */
40 	struct work_struct work;
41 	struct mutex	   lock;
42 	atomic_t	   priority;
43 	struct tty_buffer sentinel;
44 	struct llist_head free;		/* Free queue head */
45 	atomic_t	   mem_used;    /* In-use buffers excluding free list */
46 	int		   mem_limit;
47 	struct tty_buffer *tail;	/* Active buffer */
48 };
49 
50 /*
51  * When a break, frame error, or parity error happens, these codes are
52  * stuffed into the flags buffer.
53  */
54 #define TTY_NORMAL	0
55 #define TTY_BREAK	1
56 #define TTY_FRAME	2
57 #define TTY_PARITY	3
58 #define TTY_OVERRUN	4
59 
60 #endif
61