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 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
25 static inline u8 *char_buf_ptr(struct tty_buffer *b, unsigned int ofs)
26 {
27 return b->data + ofs;
28 }
29
30 static inline u8 *flag_buf_ptr(struct tty_buffer *b, unsigned int ofs)
31 {
32 return char_buf_ptr(b, ofs) + b->size;
33 }
34
35 struct 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
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