serial.c ( File view )

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			/*
* 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.
*/
/*
* serial.c
* 该程序用于实现rs232 的输入输出功能
* void rs_write(struct tty_struct *queue);
* void rs_init(void);
* 以及与传输IO 有关系的所有中断处理程序。
*/

#include <linux/tty.h>		// tty 头文件,定义了有关tty_io,串行通信方面的参数、常数。
#include <linux/sched.h>	// 调度程序头文件,定义了任务结构task_struct、初始任务0 的数据,
// 还有一些有关描述符参数设置和获取的嵌入式汇编函数宏语句。
#include <asm/system.h>		// 段操作头文件。定义了有关段寄存器操作的嵌入式汇编函数。
#include <asm/io.h>		// io 头文件。定义硬件端口输入/输出宏汇编语句。

#define WAKEUP_CHARS (TTY_BUF_SIZE/4)	// 当写队列中含有WAKEUP_CHARS 个字符时,就开始发送。

extern void rs1_interrupt (void);	// 串行口1 的中断处理程序(rs_io.s, 34)。
extern void rs2_interrupt (void);	// 串行口2 的中断处理程序(rs_io.s, 38)。

//// 初始化串行端口
// port: 串口1 - 0x3F8,串口2 - 0x2F8。
static void
init (int port)
{

  outb_p (0x80, port + 3);	/* set DLAB of line control reg */
/* 设置线路控制寄存器的DLAB 位(位7) */
  outb_p (0x30, port);		/* LS of divisor (48 -> 2400 bps */
/* 发送波特率因子低字节,0x30->2400bps */
  outb_p (0x00, port + 1);	/* MS of divisor */
/* 发送波特率因子高字节,0x00 */
  outb_p (0x03, port + 3);	/* reset DLAB */
/* 复位DLAB 位,数据位为8 位 */
  outb_p (0x0b, port + 4);	/* set DTR,RTS, OUT_2 */
/* 设置DTR,RTS,辅助用户输出2 */
  outb_p (0x0d, port + 1);	/* enable all intrs but writes */
/* 除了写(写保持空)以外,允许所有中断源中断 */
  (void) inb (port);		/* read data port to reset things (?) */
/* 读数据口,以进行复位操作(?) */

}

//// 初始化串行中断程序和串行接口。
void
rs_init (void)
{

  set_intr_gate (0x24, rs1_interrupt);	// 设置串行口1 的中断门向量(硬件IRQ4 信号)。
  set_intr_gate (0x23, rs2_interrupt);	// 设置串行口2 的中断门向量(硬件IRQ3 信号)。
  init (tty_table[1].read_q.data);	// 初始化串行口1(.data 是端口号)。
  init (tty_table[2].read_q.data);	// 初始化串行口2。
  outb (inb_p (0x21) & 0xE7, 0x21);	// 允许主8259A 芯片的IRQ3,IRQ4 中断信号请求。

}

/*
* 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);
*/
/*
* 在tty_write()已将数据放入输出(写)队列时会调用下面的子程序。必须首先
* 检查写队列是否为空,并相应设置中断寄存器。
*/
//// 串行数据发送输出。
// 实际上只是开启串行发送保持寄存器已空中断标志,在UART 将数据发送出去后允许发中断信号。
void
rs_write (struct tty_struct *tty)
{

  cli ();			// 关中断。
// 如果写队列不空,则从0x3f9(或0x2f9) 首先读取中断允许寄存器内容,添上发送保持寄存器
// 中断允许标志(位1)后,再写回该寄存器。
  if (!EMPTY (tty->write_q))
    outb (inb_p (tty->write_q.data + 1) | 0x02, tty->write_q.data + 1);
  sti ();			// 开中断。

}
			
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linux0.00 B0% 04-10-07
<boot>0.00 B04-10-07 15:01
bootsect.s12.49 kB08-01-04 21:38
head.s13.22 kB08-01-04 21:38
setup.s12.42 kB08-01-04 21:38
<fs>0.00 B04-10-07 15:01
bitmap.c8.46 kB02-09-04 13:12
block_dev.c3.95 kB02-09-04 13:12
buffer.c17.71 kB02-09-04 13:12
char_dev.c4.09 kB02-09-04 13:12
exec.c18.90 kB02-09-04 13:12
fcntl.c3.33 kB02-09-04 13:12
file_dev.c4.82 kB02-09-04 13:12
file_table.c209.00 B02-09-04 13:12
inode.c14.92 kB02-09-04 13:12
ioctl.c1.94 kB02-09-04 13:12
Makefile6.80 kB08-01-04 21:45
namei.c37.20 kB02-09-04 13:12
open.c10.00 kB02-09-04 13:12
pipe.c5.42 kB02-09-04 13:12
read_write.c5.86 kB02-09-04 13:12
stat.c2.69 kB02-09-04 13:12
super.c13.57 kB02-09-04 13:12
truncate.c2.46 kB02-09-04 13:12
<include>0.00 B04-10-07 15:01
a.out.h8.22 kB02-09-04 13:14
<asm>0.00 B04-10-07 15:01
io.h772.00 B02-09-04 13:14
memory.h1.03 kB08-01-04 22:13
segment.h2.50 kB02-09-04 13:14
system.h4.08 kB02-09-04 13:14
const.h589.00 B02-09-04 13:14
ctype.h1.68 kB02-09-04 13:14
errno.h2.30 kB02-09-04 13:14
fcntl.h3.30 kB02-09-04 13:14
<linux>0.00 B04-10-07 15:01
config.h2.16 kB02-09-04 13:14
fs.h9.72 kB02-09-04 13:14
hdreg.h2.94 kB02-09-04 13:14
head.h760.00 B02-09-04 13:14
kernel.h1.44 kB02-09-04 13:14
mm.h473.00 B02-09-04 13:14
sched.h13.25 kB02-09-04 13:14
sys.h5.41 kB02-09-04 13:14
tty.h3.93 kB02-09-04 13:14
signal.h4.01 kB02-09-04 13:14
stdarg.h1.77 kB02-09-04 13:14
stddef.h378.00 B02-09-04 13:14
string.h21.75 kB02-09-04 13:14
<sys>0.00 B04-10-07 15:01
stat.h2.37 kB02-09-04 13:14
times.h377.00 B02-09-04 13:14
types.h1.10 kB02-09-04 13:14
utsname.h423.00 B02-09-04 13:14
wait.h1.48 kB02-09-04 13:14
termios.h13.58 kB02-09-04 13:14
time.h1.81 kB02-09-04 13:14
unistd.h9.21 kB02-09-04 13:14
utime.h392.00 B02-09-04 13:14
<init>0.00 B04-10-07 15:01
main.c12.52 kB02-09-04 13:12
<kernel>0.00 B04-10-07 15:01
asm.s5.10 kB08-01-04 22:48
<blk_drv>0.00 B04-10-07 15:01
blk.h5.69 kB02-09-04 13:14
floppy.c23.49 kB02-09-04 13:12
hd.c17.14 kB02-09-04 13:12
ll_rw_blk.c7.59 kB02-09-04 13:12
Makefile4.25 kB08-01-04 22:53
ramdisk.c6.13 kB02-09-04 13:12
<chr_drv>0.00 B04-10-07 15:01
console.c30.91 kB02-09-04 13:12
keyboard.S21.04 kB08-01-04 22:59
Makefile4.81 kB08-01-04 22:59
rs_io.s5.75 kB08-01-04 22:59
serial.c2.91 kB02-09-04 13:12
tty_io.c18.40 kB02-09-04 13:12
tty_ioctl.c10.70 kB02-09-04 13:12
exit.c8.08 kB02-09-04 13:12
fork.c6.78 kB15-07-07 22:10
<math>0.00 B04-10-07 15:01
Makefile3.21 kB08-01-04 23:01
math_emulate.c2.08 kB02-09-04 13:12
mktime.c2.72 kB02-09-04 13:12
panic.c952.00 B02-09-04 13:12
printk.c1.75 kB02-09-04 13:12
sched.c18.57 kB16-07-07 21:23
signal.c5.61 kB02-09-04 13:12
sys.c7.62 kB02-09-04 13:12
system_call.s12.53 kB08-01-04 22:48
traps.c8.29 kB04-10-07 14:57
vsprintf.c9.96 kB02-09-04 13:12
<lib>0.00 B04-10-07 15:01
close.c397.00 B02-09-04 13:12
ctype.c1.72 kB02-09-04 13:12
dup.c401.00 B02-09-04 13:12
errno.c66.00 B02-09-04 13:12
execve.c607.00 B02-09-04 13:12
Makefile4.83 kB08-01-04 22:30
malloc.c13.50 kB02-09-04 13:12
open.c1.22 kB02-09-04 13:12
setsid.c382.00 B02-09-04 13:12
string.c199.00 B02-09-04 13:12
wait.c774.00 B02-09-04 13:12
write.c545.00 B02-09-04 13:12
_exit.c616.00 B02-09-04 13:12
Makefile8.58 kB08-01-04 22:21
<mm>0.00 B04-10-07 15:01
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page.s842.00 B08-01-04 22:34
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