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 return ((unsigned char *)b->data) + ofs; 30 } 31 32 static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs) 33 { 34 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 60