serial.c

arm平台上的uclinux系统全部源代码

/*
 *  linux/arch/arm/drivers/char/serial.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Extensively rewritten by Theodore Ts'o, 8/16/92 -- 9/14/92.  Now
 *  much more extensible to support other serial cards based on the
 *  16450/16550A UART's.  Added support for the AST FourPort and the
 *  Accent Async board.  
 *
 *  set_serial_info fixed to set the flags, custom divisor, and uart
 * 	type fields.  Fix suggested by Michael K. Johnson 12/12/92.
 *
 *  11/95: TIOCMIWAIT, TIOCGICOUNT by Angelo Haritsis <[e-mail]>
 *
 *  03/96: Modularised by Angelo Haritsis <[e-mail]>
 *
 *  rs_set_termios fixed to look also for changes of the input
 *      flags INPCK, BRKINT, PARMRK, IGNPAR and IGNBRK.
 *						Bernd Anh鋟pl 05/17/96.
 *
 * This module exports the following rs232 io functions:
 *
 *	int rs_init(void);
 * 	int rs_open(struct tty_struct * tty, struct file * filp)
 *
 *  Slight modifications for ARM Copyright (C) 1995, 1996 Russell King
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/serial_reg.h>
#include <linux/config.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/segment.h>
#include <asm/bitops.h>
#include <asm/serial.h>

static char *serial_name = "Serial driver";
static char *serial_version = "4.13";

DECLARE_TASK_QUEUE(tq_serial);

struct tty_driver serial_driver, callout_driver;
static int serial_refcount;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL	1
#define SERIAL_TYPE_CALLOUT	2

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

/*
 * Serial driver configuration section.  Here are the various options:
 *
 * CONFIG_HUB6
 *		Enables support for the venerable Bell Technologies
 *		HUB6 card.
 *
 * SERIAL_PARANOIA_CHECK
 * 		Check the magic number for the async_structure where
 * 		ever possible.
 */

#define SERIAL_PARANOIA_CHECK
#define CONFIG_SERIAL_NOPAUSE_IO
#define SERIAL_DO_RESTART

#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW

#define RS_STROBE_TIME (10*HZ)
#define RS_ISR_PASS_LIMIT 256

#define IRQ_T(info) ((info->flags & ASYNC_SHARE_IRQ) ? SA_SHIRQ : SA_INTERRUPT)

#define _INLINE_ inline

#if defined(MODULE) && defined(SERIAL_DEBUG_MCOUNT)
#define DBG_CNT(s) printk("(%s): [%x] refc=%d, serc=%d, ttyc=%d -> %s\n", \
 kdevname(tty->device), (info->flags), serial_refcount,info->count,tty->count,s)
#else
#define DBG_CNT(s)
#endif
  
/*
 * IRQ_timeout		- How long the timeout should be for each IRQ
 * 				should be after the IRQ has been active.
 */

static struct async_struct *IRQ_ports[NR_IRQS];
static struct rs_multiport_struct rs_multiport[NR_IRQS];
static int IRQ_timeout[NR_IRQS];
static volatile int rs_irq_triggered;
static volatile int rs_triggered;
static int rs_wild_int_mask;

static void autoconfig(struct async_struct * info);
static void change_speed(struct async_struct *info);

struct async_struct rs_table[] = {
	RS_UARTS
};

#define NR_PORTS	(sizeof(rs_table)/sizeof(struct async_struct))

static struct tty_struct *serial_table[NR_PORTS];
static struct termios *serial_termios[NR_PORTS];
static struct termios *serial_termios_locked[NR_PORTS];

#ifndef MIN
#define MIN(a,b)	((a) < (b) ? (a) : (b))
#endif

/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the memcpy_fromfs blocks while swapping in a page,
 * and some other program tries to do a serial write at the same time.
 * Since the lock will only come under contention when the system is
 * swapping and available memory is low, it makes sense to share one
 * buffer across all the serial ports, since it significantly saves
 * memory if large numbers of serial ports are open.
 */
static unsigned char *tmp_buf;
static struct semaphore tmp_buf_sem = MUTEX;

static inline int serial_paranoia_check(struct async_struct *info,
					kdev_t device, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for serial struct (%s) in %s\n";
	static const char *badinfo =
		"Warning: null async_struct for (%s) in %s\n";

	if (!info) {
		printk(badinfo, kdevname(device), routine);
		return 1;
	}
	if (info->magic != SERIAL_MAGIC) {
		printk(badmagic, kdevname(device), routine);
		return 1;
	}
#endif
	return 0;
}

/*
 * This is used to figure out the divisor speeds and the timeouts
 */
static int baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 0 };

static inline unsigned int serial_in(struct async_struct *info, int offset)
{
#ifdef CONFIG_HUB6
    if (info->hub6) {
	outb(info->hub6 - 1 + offset, info->port);
	return inb(info->port+1);
    } else
#endif
	return inb(info->port + offset);
}

static inline unsigned int serial_inp(struct async_struct *info, int offset)
{
#ifdef CONFIG_HUB6
    if (info->hub6) {
	outb(info->hub6 - 1 + offset, info->port);
	return inb_p(info->port+1);
    } else
#endif
#ifdef CONFIG_SERIAL_NOPAUSE_IO
	return inb(info->port + offset);
#else
	return inb_p(info->port + offset);
#endif
}

static inline void serial_out(struct async_struct *info, int offset, int value)
{
#ifdef CONFIG_HUB6
    if (info->hub6) {
	outb(info->hub6 - 1 + offset, info->port);
	outb(value, info->port+1);
    } else
#endif
	outb(value, info->port+offset);
}

static inline void serial_outp(struct async_struct *info, int offset,
			       int value)
{
#ifdef CONFIG_HUB6
    if (info->hub6) {
	outb(info->hub6 - 1 + offset, info->port);
	outb_p(value, info->port+1);
    } else
#endif
#ifdef CONFIG_SERIAL_NOPAUSE_IO
	outb(value, info->port+offset);
#else
    	outb_p(value, info->port+offset);
#endif
}

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "rs_stop"))
		return;
	
	save_flags_cli (flags);
	if (info->IER & UART_IER_THRI) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
	restore_flags(flags);
}

static void rs_start(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;
	
	if (serial_paranoia_check(info, tty->device, "rs_start"))
		return;
	
	save_flags_cli (flags);
	if (info->xmit_cnt && info->xmit_buf && !(info->IER & UART_IER_THRI)) {
		info->IER |= UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
	restore_flags(flags);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * rs_interrupt().  They were separated out for readability's sake.
 *
 * Note: rs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * rs_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 * 
 * gcc -S -DKERNEL -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer serial.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 * 				- Ted Ts'o ([e-mail]), 7-Mar-93
 * -----------------------------------------------------------------------
 */

/*
 * This is the serial driver's interrupt routine while we are probing
 * for submarines.
 */
static void rs_probe(int irq, void *dev_id, struct pt_regs * regs)
{
	rs_irq_triggered = irq;
	rs_triggered |= 1 << irq;
	return;
}

/*
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 */
static _INLINE_ void rs_sched_event(struct async_struct *info,
				  int event)
{
	info->event |= 1 << event;
	queue_task_irq_off(&info->tqueue, &tq_serial);
	mark_bh(SERIAL_BH);
}

static _INLINE_ void receive_chars(struct async_struct *info,
				 int *status)
{
	struct tty_struct *tty = info->tty;
	unsigned char ch;
	int ignored = 0;

	do {
		ch = serial_inp(info, UART_RX);
		if (*status & info->ignore_status_mask) {
			if (++ignored > 100)
				break;
			goto ignore_char;
		}
		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			break;
		tty->flip.count++;
		if (*status & (UART_LSR_BI)) {
#ifdef SERIAL_DEBUG_INTR
			printk("handling break....");
#endif
			*tty->flip.flag_buf_ptr++ = TTY_BREAK;
			if (info->flags & ASYNC_SAK)
				do_SAK(tty);
		} else if (*status & UART_LSR_PE)
			*tty->flip.flag_buf_ptr++ = TTY_PARITY;
		else if (*status & UART_LSR_FE)
			*tty->flip.flag_buf_ptr++ = TTY_FRAME;
		else if (*status & UART_LSR_OE) 
			*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
		else
			*tty->flip.flag_buf_ptr++ = 0;
		*tty->flip.char_buf_ptr++ = ch;
	ignore_char:
		*status = serial_inp(info, UART_LSR) & info->read_status_mask;
	} while (*status & UART_LSR_DR);
	queue_task_irq_off(&tty->flip.tqueue, &tq_timer);
#ifdef SERIAL_DEBUG_INTR
	printk("DR...");
#endif
}

static _INLINE_ void transmit_chars(struct async_struct *info, int *intr_done)
{
	int count;
	
	if (info->x_char) {
		serial_outp(info, UART_TX, info->x_char);
		info->x_char = 0;
		if (intr_done)
			*intr_done = 0;
		return;
	}
	if ((info->xmit_cnt <= 0) || info->tty->stopped ||
	    info->tty->hw_stopped) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
		return;
	}
	
	count = info->xmit_fifo_size;
	do {
		serial_out(info, UART_TX, info->xmit_buf[info->xmit_tail++]);
		info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
		if (--info->xmit_cnt <= 0)
			break;
	} while (--count > 0);
	
	if (info->xmit_cnt < WAKEUP_CHARS)
		rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);

#ifdef SERIAL_DEBUG_INTR
	printk("THRE...");
#endif
	if (intr_done)
		*intr_done = 0;

	if (info->xmit_cnt <= 0) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
}

static _INLINE_ void check_modem_status(struct async_struct *info)
{
	int	status;
	
	status = serial_in(info, UART_MSR);

	if (status & UART_MSR_ANY_DELTA) {
		/* update input line counters */
		if (status & UART_MSR_TERI)
			info->icount.rng++;
		if (status & UART_MSR_DDSR)
			info->icount.dsr++;
		if (status & UART_MSR_DDCD)
			info->icount.dcd++;
		if (status & UART_MSR_DCTS)
			info->icount.cts++;
		wake_up_interruptible(&info->delta_msr_wait);
	}

	if ((info->flags & ASYNC_CHECK_CD) && (status & UART_MSR_DDCD)) {
#if (defined(SERIAL_DEBUG_OPEN) || defined(SERIAL_DEBUG_INTR))
		printk("ttys%d CD now %s...", info->line,
		       (status & UART_MSR_DCD) ? "on" : "off");
#endif		
		if (status & UART_MSR_DCD)
			wake_up_interruptible(&info->open_wait);
		else if (!((info->flags & ASYNC_CALLOUT_ACTIVE) &&
			   (info->flags & ASYNC_CALLOUT_NOHUP))) {
#ifdef SERIAL_DEBUG_OPEN
			printk("scheduling hangup...");
#endif
			queue_task_irq_off(&info->tqueue_hangup,
					   &tq_scheduler);
		}
	}
	if (info->flags & ASYNC_CTS_FLOW) {
		if (info->tty->hw_stopped) {
			if (status & UART_MSR_CTS) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx start...");
#endif
				info->tty->hw_stopped = 0;
				info->IER |= UART_IER_THRI;
				serial_out(info, UART_IER, info->IER);
				rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);
				return;
			}
		} else {
			if (!(status & UART_MSR_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx stop...");
#endif
				info->tty->hw_stopped = 1;
				info->IER &= ~UART_IER_THRI;
				serial_out(info, UART_IER, info->IER);
			}
		}
	}
}

/*
 * This is the serial driver's generic interrupt routine
 */
static void rs_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	int status;
	struct async_struct * info;
	int pass_counter = 0;
	struct async_struct *end_mark = 0;
	int first_multi = 0;
	struct rs_multiport_struct *multi;

#ifdef SERIAL_DEBUG_INTR
	printk("rs_interrupt(%d)...", irq);
#endif
	
	info = IRQ_ports[irq];
	if (!info)
		return;
	
	multi = &rs_multiport[irq];
	if (multi->port_monitor)
		first_multi = inb(multi->port_monitor);

	do {
		if (!info->tty ||
		    (serial_in(info, UART_IIR) & UART_IIR_NO_INT)) {
			if (!end_mark)
				end_mark = info;
			goto next;
		}
		end_mark = 0;

		info->last_active = jiffies;

		status = serial_inp(info, UART_LSR) & info->read_status_mask;
#ifdef SERIAL_DEBUG_INTR
		printk("status = %x...", status);
#endif
		if (status & UART_LSR_DR)
			receive_chars(info, &status);
		check_modem_status(info);
		if (status & UART_LSR_THRE)
			transmit_chars(info, 0);

	next:
		info = info->next_port;
		if (!info) {
			info = IRQ_ports[irq];
			if (pass_counter++ > RS_ISR_PASS_LIMIT) {
#if 0
				printk("rs loop break\n");
#endif
				break; 	/* Prevent infinite loops */