serial.c

In the ffuart.tar.gz it has one file. The serial.c is the source codes of the FFUART as a console

	serial_icr_write(info, UART_ACR, info->ACR | UART_ACR_ICRRD);
	serial_out(info, UART_SCR, offset);
	value = serial_in(info, UART_ICR);
	serial_icr_write(info, UART_ACR, info->ACR);
	return value;
}

/*
 * ------------------------------------------------------------
 * 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(flags); cli();
	if (info->IER & UART_IER_THRI) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
	if (info->state->type == PORT_16C950) {
		info->ACR |= UART_ACR_TXDIS;
		serial_icr_write(info, UART_ACR, info->ACR);
	}
	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(flags); cli();
	if (info->xmit.head != info->xmit.tail
	    && info->xmit.buf
	    && !(info->IER & UART_IER_THRI)) {
		info->IER |= UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
	if (info->state->type == PORT_16C950) {
		info->ACR &= ~UART_ACR_TXDIS;
		serial_icr_write(info, UART_ACR, info->ACR);
	}
	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 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(&info->tqueue, &tq_serial);
	mark_bh(SERIAL_BH);
}

static _INLINE_ void receive_chars(struct async_struct *info,
				 int *status, struct pt_regs * regs)
{
	struct tty_struct *tty = info->tty;
	unsigned char ch;
	struct	async_icount *icount;
	int	max_count = 256;

	icount = &info->state->icount;
	do {
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			tty->flip.tqueue.routine((void *) tty);
			if (tty->flip.count >= TTY_FLIPBUF_SIZE)
				return;		// if TTY_DONT_FLIP is set
		}
		ch = serial_inp(info, UART_RX);
		*tty->flip.char_buf_ptr = ch;
		icount->rx++;
		
#ifdef SERIAL_DEBUG_INTR
		printk("DR%02x:%02x...", ch, *status);
#endif
		*tty->flip.flag_buf_ptr = 0;
		if (*status & (UART_LSR_BI | UART_LSR_PE |
			       UART_LSR_FE | UART_LSR_OE)) {
			/*
			 * For statistics only
			 */
			if (*status & UART_LSR_BI) {
				*status &= ~(UART_LSR_FE | UART_LSR_PE);
				icount->brk++;
				/*
				 * We do the SysRQ and SAK checking
				 * here because otherwise the break
				 * may get masked by ignore_status_mask
				 * or read_status_mask.
				 */
#if defined(CONFIG_SERIAL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
				if (info->line == sercons.index) {
					if (!break_pressed) {
						break_pressed = jiffies;
						goto ignore_char;
					}
					break_pressed = 0;
				}
#endif
				if (info->flags & ASYNC_SAK)
					do_SAK(tty);
			} else if (*status & UART_LSR_PE)
				icount->parity++;
			else if (*status & UART_LSR_FE)
				icount->frame++;
			if (*status & UART_LSR_OE)
				icount->overrun++;

			/*
			 * Mask off conditions which should be ignored.
			 */
			*status &= info->read_status_mask;

#ifdef CONFIG_SERIAL_CONSOLE
			if (info->line == sercons.index) {
				/* Recover the break flag from console xmit */
				*status |= lsr_break_flag;
				lsr_break_flag = 0;
			}
#endif
			if (*status & (UART_LSR_BI)) {
#ifdef SERIAL_DEBUG_INTR
				printk("handling break....");
#endif
				*tty->flip.flag_buf_ptr = TTY_BREAK;
			} 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;
		}
#if defined(CONFIG_SERIAL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
		if (break_pressed && info->line == sercons.index) {
			if (ch != 0 &&
			    time_before(jiffies, break_pressed + HZ*5)) {
				handle_sysrq(ch, regs, NULL, NULL);
				break_pressed = 0;
				goto ignore_char;
			}
			break_pressed = 0;
		}
#endif
		if ((*status & info->ignore_status_mask) == 0) {
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}
		if ((*status & UART_LSR_OE) &&
		    (tty->flip.count < TTY_FLIPBUF_SIZE)) {
			/*
			 * Overrun is special, since it's reported
			 * immediately, and doesn't affect the current
			 * character
			 */
			*tty->flip.flag_buf_ptr = TTY_OVERRUN;
			tty->flip.count++;
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
		}
#if defined(CONFIG_SERIAL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
	ignore_char:
#endif
		*status = serial_inp(info, UART_LSR);
	} while ((*status & UART_LSR_DR) && (max_count-- > 0));
#if (LINUX_VERSION_CODE > 131394) /* 2.1.66 */
	tty_flip_buffer_push(tty);
#else
	queue_task_irq_off(&tty->flip.tqueue, &tq_timer);
#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->state->icount.tx++;
		info->x_char = 0;
		if (intr_done)
			*intr_done = 0;
		return;
	}
	if (info->xmit.head == info->xmit.tail
	    || 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 + 1) & (SERIAL_XMIT_SIZE-1);
		info->state->icount.tx++;
		if (info->xmit.head == info->xmit.tail)
			break;
	} while (--count > 0);
	
	if (CIRC_CNT(info->xmit.head,
		     info->xmit.tail,
		     SERIAL_XMIT_SIZE) < 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.head == info->xmit.tail) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_IER, info->IER);
	}
}

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

	if (status & UART_MSR_ANY_DELTA) {
		icount = &info->state->icount;
		/* update input line counters */
		if (status & UART_MSR_TERI)
			icount->rng++;
		if (status & UART_MSR_DDSR)
			icount->dsr++;
		if (status & UART_MSR_DDCD) {
			icount->dcd++;
#ifdef CONFIG_HARD_PPS
			if ((info->flags & ASYNC_HARDPPS_CD) &&
			    (status & UART_MSR_DCD))
				hardpps();
#endif
		}
		if (status & UART_MSR_DCTS)
			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("doing serial hangup...");
#endif
			if (info->tty)
				tty_hangup(info->tty);
		}
	}
	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);
			}
		}
	}
}

#ifdef CONFIG_SERIAL_SHARE_IRQ
/*
 * 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;
#ifdef CONFIG_SERIAL_MULTIPORT	
	int first_multi = 0;
	struct rs_multiport_struct *multi;
#endif

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

	info = IRQ_ports[irq];
	if (!info)
		return;

#ifdef CONFIG_SERIAL_MULTIPORT	
	multi = &rs_multiport[irq];
	if (multi->port_monitor)
		first_multi = inb(multi->port_monitor);
#endif

	do {
		if (!info->tty ||
		    (serial_in(info, UART_IIR) & UART_IIR_NO_INT)) {
			if (!end_mark)
				end_mark = info;
			goto next;
		}
#ifdef SERIAL_DEBUG_INTR
		printk("IIR = %x...", serial_in(info, UART_IIR));
#endif
		end_mark = 0;

		info->last_active = jiffies;

		status = serial_inp(info, UART_LSR);
#ifdef SERIAL_DEBUG_INTR
		printk("status = %x...", status);
#endif
		if (status & UART_LSR_DR)
			receive_chars(info, &status, regs);
		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 */
			}
			continue;
		}
	} while (end_mark != info);
#ifdef CONFIG_SERIAL_MULTIPORT	
	if (multi->port_monitor)
		printk("rs port monitor (normal) irq %d: 0x%x, 0x%x\n",
		       info->state->irq, first_multi,
		       inb(multi->port_monitor));
#endif
#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}
#endif /* #ifdef CONFIG_SERIAL_SHARE_IRQ */


/*
 * This is the serial driver's interrupt routine for a single port
 */
static void rs_interrupt_single(int irq, void *dev_id, struct pt_regs * regs)
{
	int status;
	int pass_counter = 0;
	struct async_struct * info;
#ifdef CONFIG_SERIAL_MULTIPORT	
	int first_multi = 0;
	struct rs_multiport_struct *multi;
#endif
	
#ifdef SERIAL_DEBUG_INTR
	printk("rs_interrupt_single(%d)...", irq);
#endif

	info = IRQ_ports[irq];
	if (!info || !info->tty)
		return;

#ifdef CONFIG_SERIAL_MULTIPORT	
	multi = &rs_multiport[irq];
	if (multi->port_monitor)
		first_multi = inb(multi->port_monitor);
#endif

	do {
		status = serial_inp(info, UART_LSR);
#ifdef SERIAL_DEBUG_INTR
		printk("status = %x...", status);
#endif
		if (status & UART_LSR_DR)
			receive_chars(info, &status, regs);
		check_modem_status(info);
		if (status & UART_LSR_THRE)
			transmit_chars(info, 0);
		if (pass_counter++ > RS_ISR_PASS_LIMIT) {
#if 0
			printk("rs_single loop break.\n");
#endif
			break;
		}
#ifdef SERIAL_DEBUG_INTR
		printk("IIR = %x...", serial_in(info, UART_IIR));
#endif
	} while (!(serial_in(info, UART_IIR) & UART_IIR_NO_INT));
	info->last_active = jiffies;
#ifdef CONFIG_SERIAL_MULTIPORT	
	if (multi->port_monitor)
		printk("rs port monitor (single) irq %d: 0x%x, 0x%x\n",
		       info->state->irq, first_multi,
		       inb(multi->port_monitor));
#endif
#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}

#ifdef CONFIG_SERIAL_MULTIPORT	
/*
 * This is the serial driver's for multiport boards
 */
static void rs_interrupt_multi(int irq, void *dev_id, struct pt_regs * regs)
{
	int status;
	struct async_struct * info;
	int pass_counter = 0;
	int first_multi= 0;
	struct rs_multiport_struct *multi;

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

	info = IRQ_ports[irq];
	if (!info)
		return;
	multi = &rs_multiport[irq];
	if (!multi->port1) {
		/* Should never happen */
		printk("rs_interrupt_multi: NULL port1!\n");
		return;
	}
	if (multi->port_monitor)
		first_multi = inb(multi->port_monitor);
	
	while (1) {
		if (!info->tty ||
		    (serial_in(info, UART_IIR) & UART_IIR_NO_INT))
			goto next;