ADD file via upload

0/linux/kernel/chr_drv/serial.c

@@ -0,0 +1,59 @@
+/*
+ *  linux/kernel/serial.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+/*
+ *	serial.c
+ *
+ * This module implements the rs232 io functions
+ *	void rs_write(struct tty_struct * queue);
+ *	void rs_init(void);
+ * and all interrupts pertaining to serial IO.
+ */
+
+#include <linux/tty.h>
+#include <linux/sched.h>
+#include <asm/system.h>
+#include <asm/io.h>
+
+#define WAKEUP_CHARS (TTY_BUF_SIZE/4)
+
+extern void rs1_interrupt(void);
+extern void rs2_interrupt(void);
+
+static void init(int port)
+{
+	outb_p(0x80,port+3);	/* set DLAB of line control reg */
+	outb_p(0x30,port);	/* LS of divisor (48 -> 2400 bps */
+	outb_p(0x00,port+1);	/* MS of divisor */
+	outb_p(0x03,port+3);	/* reset DLAB */
+	outb_p(0x0b,port+4);	/* set DTR,RTS, OUT_2 */
+	outb_p(0x0d,port+1);	/* enable all intrs but writes */
+	(void)inb(port);	/* read data port to reset things (?) */
+}
+
+void rs_init(void)
+{
+	set_intr_gate(0x24,rs1_interrupt);
+	set_intr_gate(0x23,rs2_interrupt);
+	init(tty_table[1].read_q.data);
+	init(tty_table[2].read_q.data);
+	outb(inb_p(0x21)&0xE7,0x21);
+}
+
+/*
+ * This routine gets called when tty_write has put something into
+ * the write_queue. It must check wheter the queue is empty, and
+ * set the interrupt register accordingly
+ *
+ *	void _rs_write(struct tty_struct * tty);
+ */
+void rs_write(struct tty_struct * tty)
+{
+	cli();
+	if (!EMPTY(tty->write_q))
+		outb(inb_p(tty->write_q.data+1)|0x02,tty->write_q.data+1);
+	sti();
+}