sab82532.c

讲述linux的初始化过程

	} else {
		info->timeout = 0;
		info->tec_timeout = SAB82532_MAX_TEC_TIMEOUT;
		info->cec_timeout = SAB82532_MAX_CEC_TIMEOUT;
	}
	info->timeout += HZ / 50;		/* Add .02 seconds of slop */

	/* CTS flow control flags */
	if (cflag & CRTSCTS)
		info->flags |= ASYNC_CTS_FLOW;
	else
		info->flags &= ~(ASYNC_CTS_FLOW);

	if (cflag & CLOCAL)
		info->flags &= ~(ASYNC_CHECK_CD);
	else
		info->flags |= ASYNC_CHECK_CD;
	if (info->tty)
		info->tty->hw_stopped = 0;

	/*
	 * Set up parity check flag
	 * XXX: not implemented, yet.
	 */
#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

	/*
	 * Characters to ignore
	 * XXX: not implemented, yet.
	 */

	/*
	 * !!! ignore all characters if CREAD is not set
	 * XXX: not implemented, yet.
	 */
	if ((cflag & CREAD) == 0)
		info->ignore_status_mask |= SAB82532_ISR0_RPF |
					    SAB82532_ISR0_TCD |
					    SAB82532_ISR0_TIME;

	save_flags(flags); cli();
	sab82532_cec_wait(info);
	sab82532_tec_wait(info);
	writeb(dafo, &info->regs->w.dafo);
	writeb(ebrg & 0xff, &info->regs->w.bgr);
	writeb(readb(&info->regs->rw.ccr2) & ~(0xc0), &info->regs->rw.ccr2);
	writeb(readb(&info->regs->rw.ccr2) | ((ebrg >> 2) & 0xc0), &info->regs->rw.ccr2);
	if (info->flags & ASYNC_CTS_FLOW) {
		writeb(readb(&info->regs->rw.mode) & ~(SAB82532_MODE_RTS), &info->regs->rw.mode);
		writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_FRTS, &info->regs->rw.mode);
		writeb(readb(&info->regs->rw.mode) & ~(SAB82532_MODE_FCTS), &info->regs->rw.mode);
		info->interrupt_mask1 &= ~(SAB82532_IMR1_CSC);
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
	} else {
		writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_RTS, &info->regs->rw.mode);
		writeb(readb(&info->regs->rw.mode) & ~(SAB82532_MODE_FRTS), &info->regs->rw.mode);
		writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_FCTS, &info->regs->rw.mode);
		info->interrupt_mask1 |= SAB82532_IMR1_CSC;
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
	}
	writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_RAC, &info->regs->rw.mode);
	restore_flags(flags);
}

static void sab82532_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "sab82532_put_char"))
		return;

	if (!tty || !info->xmit_buf)
		return;

	save_flags(flags); cli();
	if (info->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
		restore_flags(flags);
		return;
	}

	info->xmit_buf[info->xmit_head++] = ch;
	info->xmit_head &= SERIAL_XMIT_SIZE-1;
	info->xmit_cnt++;
	restore_flags(flags);
}

static void sab82532_flush_chars(struct tty_struct *tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "sab82532_flush_chars"))
		return;

	if (info->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
	    !info->xmit_buf)
		return;

	save_flags(flags); cli();
	info->interrupt_mask1 &= ~(SAB82532_IMR1_XPR);
	writeb(info->interrupt_mask1, &info->regs->w.imr1);
	sab82532_start_tx(info);
	restore_flags(flags);
}

static int sab82532_write(struct tty_struct * tty, int from_user,
			  const unsigned char *buf, int count)
{
	int c, ret = 0;
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "sab82532_write"))
		return 0;

	if (!tty || !info->xmit_buf || !tmp_buf)
		return 0;
	    
	if (from_user)
		down(&tmp_buf_sem);
	save_flags(flags);
	while (1) {
		cli();		
		c = MIN(count, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
				   SERIAL_XMIT_SIZE - info->xmit_head));
		if (c <= 0)
			break;

		if (from_user) {
			c -= copy_from_user(tmp_buf, buf, c);
			if (!c) {
				if (!ret)
					ret = -EFAULT;
				break;
			}
			c = MIN(c, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
				       SERIAL_XMIT_SIZE - info->xmit_head));
			memcpy(info->xmit_buf + info->xmit_head, tmp_buf, c);
		} else
			memcpy(info->xmit_buf + info->xmit_head, buf, c);
		info->xmit_head = (info->xmit_head + c) & (SERIAL_XMIT_SIZE-1);
		info->xmit_cnt += c;
		restore_flags(flags);
		buf += c;
		count -= c;
		ret += c;
	}
	if (from_user)
		up(&tmp_buf_sem);

	if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped) {
		info->interrupt_mask1 &= ~(SAB82532_IMR1_XPR);
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
		sab82532_start_tx(info);
	}

	restore_flags(flags);
	return ret;
}

static int sab82532_write_room(struct tty_struct *tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	int ret;

	if (serial_paranoia_check(info, tty->device, "sab82532_write_room"))
		return 0;
	ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;
	if (ret < 0)
		ret = 0;
	return ret;
}

static int sab82532_chars_in_buffer(struct tty_struct *tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
				
	if (serial_paranoia_check(info, tty->device, "sab82532_chars_in_buffer"))
		return 0;
	return info->xmit_cnt;
}

static void sab82532_flush_buffer(struct tty_struct *tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;

	if (serial_paranoia_check(info, tty->device, "sab82532_flush_buffer"))
		return;
	cli();
	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
	sti();
	wake_up_interruptible(&tty->write_wait);
	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
	    tty->ldisc.write_wakeup)
		(tty->ldisc.write_wakeup)(tty);
}

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void sab82532_send_xchar(struct tty_struct *tty, char ch)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "sab82532_send_xchar"))
		return;

	save_flags(flags); cli();
	sab82532_tec_wait(info);
	writeb(ch, &info->regs->w.tic);
	restore_flags(flags);
}

/*
 * ------------------------------------------------------------
 * sab82532_throttle()
 * 
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void sab82532_throttle(struct tty_struct * tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
#ifdef SERIAL_DEBUG_THROTTLE
	char	buf[64];
	
	printk("throttle %s: %d....\n", _tty_name(tty, buf),
	       tty->ldisc.chars_in_buffer(tty));
#endif

	if (serial_paranoia_check(info, tty->device, "sab82532_throttle"))
		return;
	
	if (I_IXOFF(tty))
		sab82532_send_xchar(tty, STOP_CHAR(tty));
}

static void sab82532_unthrottle(struct tty_struct * tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
#ifdef SERIAL_DEBUG_THROTTLE
	char	buf[64];
	
	printk("unthrottle %s: %d....\n", _tty_name(tty, buf),
	       tty->ldisc.chars_in_buffer(tty));
#endif

	if (serial_paranoia_check(info, tty->device, "sab82532_unthrottle"))
		return;
	
	if (I_IXOFF(tty)) {
		if (info->x_char)
			info->x_char = 0;
		else
			sab82532_send_xchar(tty, START_CHAR(tty));
	}
}

/*
 * ------------------------------------------------------------
 * sab82532_ioctl() and friends
 * ------------------------------------------------------------
 */

static int get_serial_info(struct sab82532 *info,
			   struct serial_struct *retinfo)
{
	struct serial_struct tmp;
   
	if (!retinfo)
		return -EFAULT;
	memset(&tmp, 0, sizeof(tmp));
	tmp.type = info->type;
	tmp.line = info->line;
	tmp.port = (unsigned long)info->regs;
	tmp.irq = info->irq;
	tmp.flags = info->flags;
	tmp.xmit_fifo_size = info->xmit_fifo_size;
	tmp.baud_base = info->baud_base;
	tmp.close_delay = info->close_delay;
	tmp.closing_wait = info->closing_wait;
	tmp.custom_divisor = info->custom_divisor;
	tmp.hub6 = 0;
	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
		return -EFAULT;
	return 0;
}

static int set_serial_info(struct sab82532 *info,
			   struct serial_struct *new_info)
{
	return 0;
}


/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 * 	    is emptied.  On bus types like RS485, the transmitter must
 * 	    release the bus after transmitting. This must be done when
 * 	    the transmit shift register is empty, not be done when the
 * 	    transmit holding register is empty.  This functionality
 * 	    allows an RS485 driver to be written in user space. 
 */
static int get_lsr_info(struct sab82532 * info, unsigned int *value)
{
	unsigned int result;

	result = (!info->xmit_buf && info->all_sent) ? TIOCSER_TEMT : 0;
	return put_user(result, value);
}


static int get_modem_info(struct sab82532 * info, unsigned int *value)
{
	unsigned int result;

	result =  ((readb(&info->regs->r.mode) & SAB82532_MODE_RTS) ? 
		    ((readb(&info->regs->r.mode) & SAB82532_MODE_FRTS) ? 0 : TIOCM_RTS)
							    : TIOCM_RTS)
		| ((readb(&info->regs->r.pvr) & info->pvr_dtr_bit) ? 0 : TIOCM_DTR)
		| ((readb(&info->regs->r.vstr) & SAB82532_VSTR_CD) ? 0 : TIOCM_CAR)
		| ((readb(&info->regs->r.pvr) & info->pvr_dsr_bit) ? 0 : TIOCM_DSR)
		| ((readb(&info->regs->r.star) & SAB82532_STAR_CTS) ? TIOCM_CTS : 0);
	return put_user(result,value);
}

static int set_modem_info(struct sab82532 * info, unsigned int cmd,
			  unsigned int *value)
{
	int error;
	unsigned int arg;

	error = get_user(arg, value);
	if (error)
		return error;
	switch (cmd) {
	case TIOCMBIS: 
		if (arg & TIOCM_RTS) {
			writeb(readb(&info->regs->rw.mode) & ~(SAB82532_MODE_FRTS), &info->regs->rw.mode);
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_RTS, &info->regs->rw.mode);
		}
		if (arg & TIOCM_DTR) {
			writeb(readb(&info->regs->rw.pvr) & ~(info->pvr_dtr_bit), &info->regs->rw.pvr);
		}
		break;
	case TIOCMBIC:
		if (arg & TIOCM_RTS) {
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_FRTS, &info->regs->rw.mode);
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_RTS, &info->regs->rw.mode);
		}
		if (arg & TIOCM_DTR) {
			writeb(readb(&info->regs->rw.pvr) | info->pvr_dtr_bit, &info->regs->rw.pvr);
		}
		break;
	case TIOCMSET:
		if (arg & TIOCM_RTS) {
			writeb(readb(&info->regs->rw.mode) & ~(SAB82532_MODE_FRTS), &info->regs->rw.mode);
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_RTS, &info->regs->rw.mode);
		} else {
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_FRTS, &info->regs->rw.mode);
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_RTS, &info->regs->rw.mode);
		}
		if (arg & TIOCM_DTR) {
			writeb(readb(&info->regs->rw.pvr) & ~(info->pvr_dtr_bit), &info->regs->rw.pvr);
		} else {
			writeb(readb(&info->regs->rw.pvr) | info->pvr_dtr_bit, &info->regs->rw.pvr);
		}
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

/*
 * This routine sends a break character out the serial port.
 */
static void sab82532_break(struct tty_struct *tty, int break_state)
{
	struct sab82532 * info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "sab82532_break"))
		return;

	if (!info->regs)
		return;

#ifdef SERIAL_DEBUG_SEND_BREAK
	printk("sab82532_break(%d) jiff=%lu...", break_state, jiffies);
#endif
	save_flags(flags); cli();
	if (break_state == -1)
		writeb(readb(&info->regs->rw.dafo) | SAB82532_DAFO_XBRK, &info->regs->rw.dafo);
	else
		writeb(readb(&info->regs->rw.dafo) & ~(SAB82532_DAFO_XBRK), &info->regs->rw.dafo);
	restore_flags(flags);
}


static int sab82532_ioctl(struct tty_struct *tty, struct file * file,
		    unsigned int cmd, unsigned long arg)
{
	int error;
	struct sab82532 * info = (struct sab82532 *)tty->driver_data;
	struct async_icount cprev, cnow;	/* kernel counter temps */
	struct serial_icounter_struct *p_cuser;	/* user space */

	if (serial_paranoia_check(info, tty->device, "sab82532_ioctl"))
		return -ENODEV;

	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGWILD)  &&
	    (cmd != TIOCSERSWILD) && (cmd != TIOCSERGSTRUCT) &&
	    (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
		    return -EIO;
	}
	
	switch (cmd) {
		case TIOCGSOFTCAR:
			return put_user(C_CLOCAL(tty) ? 1 : 0, (int *) arg);
		case TIOCSSOFTCAR:
			error = get_user(arg, (unsigned int *) arg);
			if (error)
				return error;
			tty->termios->c_cflag =
				((tty->termios->c_cflag & ~CLOCAL) |
				 (arg ? CLOCAL : 0));
			return 0;
		case TIOCMGET:
			return get_modem_info(info, (unsigned int *) arg);
		case TIOCMBIS:
		case TIOCMBIC:
		case TIOCMSET:
			return set_modem_info(info, cmd, (unsigned int *) arg);
		case TIOCGSERIAL:
			return get_serial_info(info,
					       (struct serial_struct *) arg);
		case TIOCSSERIAL:
			return set_serial_info(info,
					       (struct serial_struct *) arg);

		case TIOCSERGETLSR: /* Get line status register */
			return get_lsr_info(info, (unsigned int *) arg);

		case TIOCSERGSTRUCT:
			if (copy_to_user((struct sab82532 *) arg,
					 info, sizeof(struct sab82532)))
				return -EFAULT;
			return 0;
				
		/*
		 * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
		 * - mask passed in arg for lines of interest
 		 *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
		 * Caller should use TIOCGICOUNT to see which one it was
		 */
		 case TIOCMIWAIT:
			cli();
			/* note the counters on entry */
			cprev = info->icount;
			sti();
			while (1) {
				interruptible_sleep_on(&info->delta_msr_wait);
				/* see if a signal did it */
				if (signal_pending(current))
					return -ERESTARTSYS;
				cli();
				cnow = info->icount; /* atomic copy */
				sti();
				if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr && 
				    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
					return -EIO; /* no change => error */
				if ( ((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
				     ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
				     ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
				     ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts)) ) {
					return 0;
				}
				cprev = cnow;
			}
			/* NOTREACHED */

		/* 
		 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)