1 files changed, 57 insertions, 0 deletions
diff --git a/include/linux/tty_buffer.h b/include/linux/tty_buffer.h
new file mode 100644
index 000000000..31125e3be
--- /dev/null
+++ b/include/linux/tty_buffer.h
@@ -0,0 +1,57 @@
+/* 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