Viewing file:  tty_buffer.h (1.29 KB) -rw-r--r--
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_TTY_BUFFER_H
#define _LINUX_TTY_BUFFER_H
#include <linux/atomic.h>
#include <linux/llist.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
struct tty_buffer {
union {
struct tty_buffer *next;
struct llist_node free;
};
unsigned int used;
unsigned int size;
unsigned int commit;
unsigned int lookahead; /* Lazy update on recv, can become less than "read" */
unsigned int read;
bool flags;
/* Data points here */
u8 data[] __aligned(sizeof(unsigned long));
};
static inline u8 *char_buf_ptr(struct tty_buffer *b, unsigned int ofs)
{
return b->data + ofs;
}
static inline u8 *flag_buf_ptr(struct tty_buffer *b, unsigned int ofs)
{
return char_buf_ptr(b, ofs) + b->size;
}
struct tty_bufhead {
struct tty_buffer *head; /* Queue head */
struct work_struct work;
struct mutex lock;
atomic_t priority;
struct tty_buffer sentinel;
struct llist_head free; /* Free queue head */
atomic_t mem_used; /* In-use buffers excluding free list */
int mem_limit;
struct tty_buffer *tail; /* Active buffer */
};
/*
* When a break, frame error, or parity error happens, these codes are
* stuffed into the flags buffer.
*/
#define TTY_NORMAL 0
#define TTY_BREAK 1
#define TTY_FRAME 2
#define TTY_PARITY 3
#define TTY_OVERRUN 4
#endif
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