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