sab82532.c

讲述linux的初始化过程

#endif
	}
	if (stat->sreg.isr1 & SAB82532_ISR1_CSC) {
		info->cts = readb(&info->regs->r.star) & SAB82532_STAR_CTS;
		info->icount.cts++;
		modem_change++;
#ifdef SERIAL_DEBUG_MODEM
		printk("CTS change: %d, CTS %s\n", info->icount.cts, info->cts ? "on" : "off");
#endif
	}
	if ((readb(&info->regs->r.pvr) & info->pvr_dsr_bit) ^ info->dsr) {
		info->dsr = (readb(&info->regs->r.pvr) & info->pvr_dsr_bit) ? 0 : 1;
		info->icount.dsr++;
		modem_change++;
#ifdef SERIAL_DEBUG_MODEM
		printk("DSR change: %d\n", info->icount.dsr);
#endif
	}
	if (modem_change)
		wake_up_interruptible(&info->delta_msr_wait);

	if ((info->flags & ASYNC_CHECK_CD) &&
	    (stat->sreg.isr0 & SAB82532_ISR0_CDSC)) {

#if (defined(SERIAL_DEBUG_OPEN) || defined(SERIAL_DEBUG_INTR))
		printk("ttys%d CD now %s...", info->line,
		       (info->dcd) ? "on" : "off");
#endif		

		if (info->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
			MOD_INC_USE_COUNT;
			if (schedule_task(&info->tqueue_hangup) == 0)
				MOD_DEC_USE_COUNT;
		}
	}

	if (info->flags & ASYNC_CTS_FLOW) {
		if (info->tty->hw_stopped) {
			if (info->cts) {

#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx start...");
#endif
				info->tty->hw_stopped = 0;
				sab82532_sched_event(info,
						     RS_EVENT_WRITE_WAKEUP);
				info->interrupt_mask1 &= ~(SAB82532_IMR1_XPR);
				writeb(info->interrupt_mask1, &info->regs->w.imr1);
				sab82532_start_tx(info);
			}
		} else {
			if (!(info->cts)) {

#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx stop...");
#endif
				info->tty->hw_stopped = 1;
			}
		}
	}
}

/*
 * This is the serial driver's generic interrupt routine
 */
static void sab82532_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct sab82532 *info = dev_id;
	union sab82532_irq_status status;

#ifdef SERIAL_DEBUG_INTR
	printk("sab82532_interrupt(%d)...", irq);
#endif

	status.stat = 0;
	if (readb(&info->regs->r.gis) & SAB82532_GIS_ISA0)
		status.sreg.isr0 = readb(&info->regs->r.isr0);
	if (readb(&info->regs->r.gis) & SAB82532_GIS_ISA1)
		status.sreg.isr1 = readb(&info->regs->r.isr1);

#ifdef SERIAL_DEBUG_INTR
	printk("%d<%02x.%02x>", info->line,
	       status.sreg.isr0, status.sreg.isr1);
#endif

	if (!status.stat)
		goto next;

	if (status.sreg.isr0 & (SAB82532_ISR0_TCD | SAB82532_ISR0_TIME |
				SAB82532_ISR0_RFO | SAB82532_ISR0_RPF))
		receive_chars(info, &status);
	if ((status.sreg.isr0 & SAB82532_ISR0_CDSC) ||
	    (status.sreg.isr1 & (SAB82532_ISR1_BRK | SAB82532_ISR1_CSC)))
		check_status(info, &status);
	if (status.sreg.isr1 & (SAB82532_ISR1_ALLS | SAB82532_ISR1_XPR))
		transmit_chars(info, &status);

next:
	info = info->next;
	status.stat = 0;
	if (readb(&info->regs->r.gis) & SAB82532_GIS_ISB0)
		status.sreg.isr0 = readb(&info->regs->r.isr0);
	if (readb(&info->regs->r.gis) & SAB82532_GIS_ISB1)
		status.sreg.isr1 = readb(&info->regs->r.isr1);

#ifdef SERIAL_DEBUG_INTR
	printk("%d<%02x.%02x>", info->line,
	       status.sreg.isr0, status.sreg.isr1);
#endif

	if (!status.stat)
		goto done;

	if (status.sreg.isr0 & (SAB82532_ISR0_TCD | SAB82532_ISR0_TIME |
				SAB82532_ISR0_RFO | SAB82532_ISR0_RPF))
		receive_chars(info, &status);
	if ((status.sreg.isr0 & SAB82532_ISR0_CDSC) ||
	    (status.sreg.isr1 & (SAB82532_ISR1_BRK | SAB82532_ISR1_CSC)))
		check_status(info, &status);
	if (status.sreg.isr1 & (SAB82532_ISR1_ALLS | SAB82532_ISR1_XPR))
		transmit_chars(info, &status);

done:
#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * sab82532_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using sab82532_sched_event(), and they get done here.
 */
static void do_serial_bh(void)
{
	run_task_queue(&tq_serial);
}

static void do_softint(void *private_)
{
	struct sab82532	*info = (struct sab82532 *)private_;
	struct tty_struct *tty;

	tty = info->tty;
	if (!tty)
		return;

	if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &info->event)) {
		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
		    tty->ldisc.write_wakeup)
			(tty->ldisc.write_wakeup)(tty);
		wake_up_interruptible(&tty->write_wait);
	}
}

/*
 * This routine is called from the scheduler tqueue when the interrupt
 * routine has signalled that a hangup has occurred.  The path of
 * hangup processing is:
 *
 * 	serial interrupt routine -> (scheduler tqueue) ->
 * 	do_serial_hangup() -> tty->hangup() -> sab82532_hangup()
 * 
 */
static void do_serial_hangup(void *private_)
{
	struct sab82532	*info = (struct sab82532 *) private_;
	struct tty_struct *tty;

	tty = info->tty;
	if (tty)
		tty_hangup(tty);
	MOD_DEC_USE_COUNT;
}

static void
sab82532_init_line(struct sab82532 *info)
{
	unsigned char stat, tmp;

	/*
	 * Wait for any commands or immediate characters
	 */
	sab82532_cec_wait(info);
	sab82532_tec_wait(info);

	/*
	 * Clear the FIFO buffers.
	 */
	writeb(SAB82532_CMDR_RRES, &info->regs->w.cmdr);
	sab82532_cec_wait(info);
	writeb(SAB82532_CMDR_XRES, &info->regs->w.cmdr);

	/*
	 * Clear the interrupt registers.
	 */
	stat = readb(&info->regs->r.isr0);
	stat = readb(&info->regs->r.isr1);

	/*
	 * Now, initialize the UART 
	 */
	writeb(0, &info->regs->w.ccr0);				/* power-down */
	writeb(SAB82532_CCR0_MCE | SAB82532_CCR0_SC_NRZ |
	       SAB82532_CCR0_SM_ASYNC, &info->regs->w.ccr0);
	writeb(SAB82532_CCR1_ODS | SAB82532_CCR1_BCR | 7, &info->regs->w.ccr1);
	writeb(SAB82532_CCR2_BDF | SAB82532_CCR2_SSEL |
	       SAB82532_CCR2_TOE, &info->regs->w.ccr2);
	writeb(0, &info->regs->w.ccr3);
	writeb(SAB82532_CCR4_MCK4 | SAB82532_CCR4_EBRG, &info->regs->w.ccr4);
	writeb(SAB82532_MODE_RTS | SAB82532_MODE_FCTS |
	       SAB82532_MODE_RAC, &info->regs->w.mode);
	writeb(SAB82532_RFC_DPS | SAB82532_RFC_RFDF, &info->regs->w.rfc);
	switch (info->recv_fifo_size) {
		case 1:
			tmp = readb(&info->regs->w.rfc);
			tmp |= SAB82532_RFC_RFTH_1;
			writeb(tmp, &info->regs->w.rfc);
			break;
		case 4:
			tmp = readb(&info->regs->w.rfc);
			tmp |= SAB82532_RFC_RFTH_4;
			writeb(tmp, &info->regs->w.rfc);
			break;
		case 16:
			tmp = readb(&info->regs->w.rfc);
			tmp |= SAB82532_RFC_RFTH_16;
			writeb(tmp, &info->regs->w.rfc);
			break;
		default:
			info->recv_fifo_size = 32;
			/* fall through */
		case 32:
			tmp = readb(&info->regs->w.rfc);
			tmp |= SAB82532_RFC_RFTH_32;
			writeb(tmp, &info->regs->w.rfc);
			break;
	}
	tmp = readb(&info->regs->rw.ccr0);
	tmp |= SAB82532_CCR0_PU;	/* power-up */
	writeb(tmp, &info->regs->rw.ccr0);
}

static int startup(struct sab82532 *info)
{
	unsigned long flags;
	unsigned long page;
	int retval = 0;

	page = get_free_page(GFP_KERNEL);
	if (!page)
		return -ENOMEM;

	save_flags(flags); cli();

	if (info->flags & ASYNC_INITIALIZED) {
		free_page(page);
		goto errout;
	}

	if (!info->regs) {
		if (info->tty)
			set_bit(TTY_IO_ERROR, &info->tty->flags);
		free_page(page);
		retval = -ENODEV;
		goto errout;
	}
	if (info->xmit_buf)
		free_page(page);
	else
		info->xmit_buf = (unsigned char *)page;

#ifdef SERIAL_DEBUG_OPEN
	printk("starting up serial port %d...", info->line);
#endif

	/*
	 * Initialize the Hardware
	 */
	sab82532_init_line(info);

	if (info->tty->termios->c_cflag & CBAUD) {
		u8 tmp;

		tmp = readb(&info->regs->rw.mode);
		tmp &= ~(SAB82532_MODE_FRTS);
		tmp |= SAB82532_MODE_RTS;
		writeb(tmp, &info->regs->rw.mode);

		tmp = readb(&info->regs->rw.pvr);
		tmp &= ~(info->pvr_dtr_bit);
		writeb(tmp, &info->regs->rw.pvr);
	}

	/*
	 * Finally, enable interrupts
	 */
	info->interrupt_mask0 = SAB82532_IMR0_PERR | SAB82532_IMR0_FERR |
				SAB82532_IMR0_PLLA;
	writeb(info->interrupt_mask0, &info->regs->w.imr0);
	info->interrupt_mask1 = SAB82532_IMR1_BRKT | SAB82532_IMR1_ALLS |
				SAB82532_IMR1_XOFF | SAB82532_IMR1_TIN |
				SAB82532_IMR1_CSC | SAB82532_IMR1_XON |
				SAB82532_IMR1_XPR;
	writeb(info->interrupt_mask1, &info->regs->w.imr1);
	info->all_sent = 1;

	if (info->tty)
		clear_bit(TTY_IO_ERROR, &info->tty->flags);
	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

	/*
	 * and set the speed of the serial port
	 */
	change_speed(info);

	info->flags |= ASYNC_INITIALIZED;
	restore_flags(flags);
	return 0;
	
errout:
	restore_flags(flags);
	return retval;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void shutdown(struct sab82532 *info)
{
	unsigned long flags;
	u8 tmp;

	if (!(info->flags & ASYNC_INITIALIZED))
		return;

#ifdef SERIAL_DEBUG_OPEN
	printk("Shutting down serial port %d...", info->line);
#endif

	save_flags(flags); cli(); /* Disable interrupts */

	/*
	 * clear delta_msr_wait queue to avoid mem leaks: we may free the irq
	 * here so the queue might never be waken up
	 */
	wake_up_interruptible(&info->delta_msr_wait);

	if (info->xmit_buf) {
		free_page((unsigned long)info->xmit_buf);
		info->xmit_buf = 0;
	}

#ifdef CONFIG_SERIAL_CONSOLE
	if (info->is_console) {
		info->interrupt_mask0 = SAB82532_IMR0_PERR | SAB82532_IMR0_FERR |
					SAB82532_IMR0_PLLA | SAB82532_IMR0_CDSC;
		writeb(info->interrupt_mask0, &info->regs->w.imr0);
		info->interrupt_mask1 = SAB82532_IMR1_BRKT | SAB82532_IMR1_ALLS |
					SAB82532_IMR1_XOFF | SAB82532_IMR1_TIN |
					SAB82532_IMR1_CSC | SAB82532_IMR1_XON |
					SAB82532_IMR1_XPR;
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
		if (info->tty)
			set_bit(TTY_IO_ERROR, &info->tty->flags);
		info->flags &= ~ASYNC_INITIALIZED;
		restore_flags(flags);
		return;
	}
#endif

	/* Disable Interrupts */
	info->interrupt_mask0 = 0xff;
	writeb(info->interrupt_mask0, &info->regs->w.imr0);
	info->interrupt_mask1 = 0xff;
	writeb(info->interrupt_mask1, &info->regs->w.imr1);

	if (!info->tty || (info->tty->termios->c_cflag & HUPCL)) {
		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);
		writeb(readb(&info->regs->rw.pvr) | info->pvr_dtr_bit, &info->regs->rw.pvr);
	}

	/* Disable break condition */
	tmp = readb(&info->regs->rw.dafo);
	tmp &= ~(SAB82532_DAFO_XBRK);
	writeb(tmp, &info->regs->rw.dafo);

	/* Disable Receiver */	
	tmp = readb(&info->regs->rw.mode);
	tmp &= ~(SAB82532_MODE_RAC);
	writeb(tmp, &info->regs->rw.mode);

	/* Power Down */	
	tmp = readb(&info->regs->rw.ccr0);
	tmp &= ~(SAB82532_CCR0_PU);
	writeb(tmp, &info->regs->rw.ccr0);

	if (info->tty)
		set_bit(TTY_IO_ERROR, &info->tty->flags);

	info->flags &= ~ASYNC_INITIALIZED;
	restore_flags(flags);
}

/*
 * This routine is called to set the UART divisor registers to match
 * the specified baud rate for a serial port.
 */
static void change_speed(struct sab82532 *info)
{
	unsigned long	flags;
	unsigned int	ebrg;
	tcflag_t	cflag;
	unsigned char	dafo;
	int		i, bits;

	if (!info->tty || !info->tty->termios)
		return;
	cflag = info->tty->termios->c_cflag;

	/* Byte size and parity */
	switch (cflag & CSIZE) {
	      case CS5: dafo = SAB82532_DAFO_CHL5; bits = 7; break;
	      case CS6: dafo = SAB82532_DAFO_CHL6; bits = 8; break;
	      case CS7: dafo = SAB82532_DAFO_CHL7; bits = 9; break;
	      case CS8: dafo = SAB82532_DAFO_CHL8; bits = 10; break;
	      /* Never happens, but GCC is too dumb to figure it out */
	      default:  dafo = SAB82532_DAFO_CHL5; bits = 7; break;
	}

	if (cflag & CSTOPB) {
		dafo |= SAB82532_DAFO_STOP;
		bits++;
	}

	if (cflag & PARENB) {
		dafo |= SAB82532_DAFO_PARE;
		bits++;
	}

	if (cflag & PARODD) {
#ifdef CMSPAR
		if (cflag & CMSPAR)
			dafo |= SAB82532_DAFO_PAR_MARK;
		else
#endif
			dafo |= SAB82532_DAFO_PAR_ODD;
	} else {
#ifdef CMSPAR
		if (cflag & CMSPAR)
			dafo |= SAB82532_DAFO_PAR_SPACE;
		else
#endif
			dafo |= SAB82532_DAFO_PAR_EVEN;
	}

	/* Determine EBRG values based on baud rate */
	i = cflag & CBAUD;
	if (i & CBAUDEX) {
		i &= ~(CBAUDEX);
		if ((i < 1) || ((i + 15) >= NR_EBRG_VALUES))
			info->tty->termios->c_cflag &= ~CBAUDEX;
		else
			i += 15;
	}
	ebrg = ebrg_table[i].n;
	ebrg |= (ebrg_table[i].m << 6);

	info->baud = ebrg_table[i].baud;
	if (info->baud) {
		info->timeout = (info->xmit_fifo_size * HZ * bits) / info->baud;
		info->tec_timeout = (10 * 1000000) / info->baud;
		info->cec_timeout = info->tec_timeout >> 2;