zs.c

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	spin_lock(&scc->zlock);
	zs_raw_stop_tx(zport);
	spin_unlock(&scc->zlock);
}

static void zs_raw_transmit_chars(struct zs_port *);

static void zs_start_tx(struct uart_port *uport)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;

	spin_lock(&scc->zlock);
	if (zport->tx_stopped) {
		zs_transmit_drain(zport, 0);
		zport->tx_stopped = 0;
		zs_raw_transmit_chars(zport);
	}
	spin_unlock(&scc->zlock);
}

static void zs_stop_rx(struct uart_port *uport)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;
	struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];

	spin_lock(&scc->zlock);
	zport->regs[15] &= ~BRKIE;
	zport->regs[1] &= ~(RxINT_MASK | TxINT_ENAB);
	zport->regs[1] |= RxINT_DISAB;

	if (zport != zport_a) {
		/* A-side DCD tracks RI and SYNC tracks DSR.  */
		zport_a->regs[15] &= ~(DCDIE | SYNCIE);
		write_zsreg(zport_a, R15, zport_a->regs[15]);
		if (!(zport_a->regs[15] & BRKIE)) {
			zport_a->regs[1] &= ~EXT_INT_ENAB;
			write_zsreg(zport_a, R1, zport_a->regs[1]);
		}

		/* This-side DCD tracks DCD and CTS tracks CTS.  */
		zport->regs[15] &= ~(DCDIE | CTSIE);
		zport->regs[1] &= ~EXT_INT_ENAB;
	} else {
		/* DCD tracks RI and SYNC tracks DSR for the B side.  */
		if (!(zport->regs[15] & (DCDIE | SYNCIE)))
			zport->regs[1] &= ~EXT_INT_ENAB;
	}

	write_zsreg(zport, R15, zport->regs[15]);
	write_zsreg(zport, R1, zport->regs[1]);
	spin_unlock(&scc->zlock);
}

static void zs_enable_ms(struct uart_port *uport)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;
	struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];

	if (zport == zport_a)
		return;

	spin_lock(&scc->zlock);

	/* Clear Ext interrupts if not being handled already.  */
	if (!(zport_a->regs[1] & EXT_INT_ENAB))
		write_zsreg(zport_a, R0, RES_EXT_INT);

	/* A-side DCD tracks RI and SYNC tracks DSR.  */
	zport_a->regs[1] |= EXT_INT_ENAB;
	zport_a->regs[15] |= DCDIE | SYNCIE;

	/* This-side DCD tracks DCD and CTS tracks CTS.  */
	zport->regs[15] |= DCDIE | CTSIE;

	zs_raw_xor_mctrl(zport);

	write_zsreg(zport_a, R1, zport_a->regs[1]);
	write_zsreg(zport_a, R15, zport_a->regs[15]);
	write_zsreg(zport, R15, zport->regs[15]);
	spin_unlock(&scc->zlock);
}

static void zs_break_ctl(struct uart_port *uport, int break_state)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;
	unsigned long flags;

	spin_lock_irqsave(&scc->zlock, flags);
	if (break_state == -1)
		zport->regs[5] |= SND_BRK;
	else
		zport->regs[5] &= ~SND_BRK;
	write_zsreg(zport, R5, zport->regs[5]);
	spin_unlock_irqrestore(&scc->zlock, flags);
}


/*
 * Interrupt handling routines.
 */
#define Rx_BRK 0x0100			/* BREAK event software flag.  */
#define Rx_SYS 0x0200			/* SysRq event software flag.  */

static void zs_receive_chars(struct zs_port *zport)
{
	struct uart_port *uport = &zport->port;
	struct zs_scc *scc = zport->scc;
	struct uart_icount *icount;
	unsigned int avail, status, ch, flag;
	int count;

	for (count = 16; count; count--) {
		spin_lock(&scc->zlock);
		avail = read_zsreg(zport, R0) & Rx_CH_AV;
		spin_unlock(&scc->zlock);
		if (!avail)
			break;

		spin_lock(&scc->zlock);
		status = read_zsreg(zport, R1) & (Rx_OVR | FRM_ERR | PAR_ERR);
		ch = read_zsdata(zport);
		spin_unlock(&scc->zlock);

		flag = TTY_NORMAL;

		icount = &uport->icount;
		icount->rx++;

		/* Handle the null char got when BREAK is removed.  */
		if (!ch)
			status |= zport->tty_break;
		if (unlikely(status &
			     (Rx_OVR | FRM_ERR | PAR_ERR | Rx_SYS | Rx_BRK))) {
			zport->tty_break = 0;

			/* Reset the error indication.  */
			if (status & (Rx_OVR | FRM_ERR | PAR_ERR)) {
				spin_lock(&scc->zlock);
				write_zsreg(zport, R0, ERR_RES);
				spin_unlock(&scc->zlock);
			}

			if (status & (Rx_SYS | Rx_BRK)) {
				icount->brk++;
				/* SysRq discards the null char.  */
				if (status & Rx_SYS)
					continue;
			} else if (status & FRM_ERR)
				icount->frame++;
			else if (status & PAR_ERR)
				icount->parity++;
			if (status & Rx_OVR)
				icount->overrun++;

			status &= uport->read_status_mask;
			if (status & Rx_BRK)
				flag = TTY_BREAK;
			else if (status & FRM_ERR)
				flag = TTY_FRAME;
			else if (status & PAR_ERR)
				flag = TTY_PARITY;
		}

		if (uart_handle_sysrq_char(uport, ch))
			continue;

		uart_insert_char(uport, status, Rx_OVR, ch, flag);
	}

	tty_flip_buffer_push(uport->info->tty);
}

static void zs_raw_transmit_chars(struct zs_port *zport)
{
	struct circ_buf *xmit = &zport->port.info->xmit;

	/* XON/XOFF chars.  */
	if (zport->port.x_char) {
		write_zsdata(zport, zport->port.x_char);
		zport->port.icount.tx++;
		zport->port.x_char = 0;
		return;
	}

	/* If nothing to do or stopped or hardware stopped.  */
	if (uart_circ_empty(xmit) || uart_tx_stopped(&zport->port)) {
		zs_raw_stop_tx(zport);
		return;
	}

	/* Send char.  */
	write_zsdata(zport, xmit->buf[xmit->tail]);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	zport->port.icount.tx++;

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&zport->port);

	/* Are we are done?  */
	if (uart_circ_empty(xmit))
		zs_raw_stop_tx(zport);
}

static void zs_transmit_chars(struct zs_port *zport)
{
	struct zs_scc *scc = zport->scc;

	spin_lock(&scc->zlock);
	zs_raw_transmit_chars(zport);
	spin_unlock(&scc->zlock);
}

static void zs_status_handle(struct zs_port *zport, struct zs_port *zport_a)
{
	struct uart_port *uport = &zport->port;
	struct zs_scc *scc = zport->scc;
	unsigned int delta;
	u8 status, brk;

	spin_lock(&scc->zlock);

	/* Get status from Read Register 0.  */
	status = read_zsreg(zport, R0);

	if (zport->regs[15] & BRKIE) {
		brk = status & BRK_ABRT;
		if (brk && !zport->brk) {
			spin_unlock(&scc->zlock);
			if (uart_handle_break(uport))
				zport->tty_break = Rx_SYS;
			else
				zport->tty_break = Rx_BRK;
			spin_lock(&scc->zlock);
		}
		zport->brk = brk;
	}

	if (zport != zport_a) {
		delta = zs_raw_xor_mctrl(zport);
		spin_unlock(&scc->zlock);

		if (delta & TIOCM_CTS)
			uart_handle_cts_change(uport,
					       zport->mctrl & TIOCM_CTS);
		if (delta & TIOCM_CAR)
			uart_handle_dcd_change(uport,
					       zport->mctrl & TIOCM_CAR);
		if (delta & TIOCM_RNG)
			uport->icount.dsr++;
		if (delta & TIOCM_DSR)
			uport->icount.rng++;

		if (delta)
			wake_up_interruptible(&uport->info->delta_msr_wait);

		spin_lock(&scc->zlock);
	}

	/* Clear the status condition...  */
	write_zsreg(zport, R0, RES_EXT_INT);

	spin_unlock(&scc->zlock);
}

/*
 * This is the Z85C30 driver's generic interrupt routine.
 */
static irqreturn_t zs_interrupt(int irq, void *dev_id)
{
	struct zs_scc *scc = dev_id;
	struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
	struct zs_port *zport_b = &scc->zport[ZS_CHAN_B];
	irqreturn_t status = IRQ_NONE;
	u8 zs_intreg;
	int count;

	/*
	 * NOTE: The read register 3, which holds the irq status,
	 *       does so for both channels on each chip.  Although
	 *       the status value itself must be read from the A
	 *       channel and is only valid when read from channel A.
	 *       Yes... broken hardware...
	 */
	for (count = 16; count; count--) {
		spin_lock(&scc->zlock);
		zs_intreg = read_zsreg(zport_a, R3);
		spin_unlock(&scc->zlock);
		if (!zs_intreg)
			break;

		/*
		 * We do not like losing characters, so we prioritise
		 * interrupt sources a little bit differently than
		 * the SCC would, was it allowed to.
		 */
		if (zs_intreg & CHBRxIP)
			zs_receive_chars(zport_b);
		if (zs_intreg & CHARxIP)
			zs_receive_chars(zport_a);
		if (zs_intreg & CHBEXT)
			zs_status_handle(zport_b, zport_a);
		if (zs_intreg & CHAEXT)
			zs_status_handle(zport_a, zport_a);
		if (zs_intreg & CHBTxIP)
			zs_transmit_chars(zport_b);
		if (zs_intreg & CHATxIP)
			zs_transmit_chars(zport_a);

		status = IRQ_HANDLED;
	}

	return status;
}


/*
 * Finally, routines used to initialize the serial port.
 */
static int zs_startup(struct uart_port *uport)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;
	unsigned long flags;
	int irq_guard;
	int ret;

	irq_guard = atomic_add_return(1, &scc->irq_guard);
	if (irq_guard == 1) {
		ret = request_irq(zport->port.irq, zs_interrupt,
				  IRQF_SHARED, "scc", scc);
		if (ret) {
			atomic_add(-1, &scc->irq_guard);
			printk(KERN_ERR "zs: can't get irq %d\n",
			       zport->port.irq);
			return ret;
		}
	}

	spin_lock_irqsave(&scc->zlock, flags);

	/* Clear the receive FIFO.  */
	zs_receive_drain(zport);

	/* Clear the interrupt registers.  */
	write_zsreg(zport, R0, ERR_RES);
	write_zsreg(zport, R0, RES_Tx_P);
	/* But Ext only if not being handled already.  */
	if (!(zport->regs[1] & EXT_INT_ENAB))
		write_zsreg(zport, R0, RES_EXT_INT);

	/* Finally, enable sequencing and interrupts.  */
	zport->regs[1] &= ~RxINT_MASK;
	zport->regs[1] |= RxINT_ALL | TxINT_ENAB | EXT_INT_ENAB;
	zport->regs[3] |= RxENABLE;
	zport->regs[5] |= TxENAB;
	zport->regs[15] |= BRKIE;
	write_zsreg(zport, R1, zport->regs[1]);
	write_zsreg(zport, R3, zport->regs[3]);
	write_zsreg(zport, R5, zport->regs[5]);
	write_zsreg(zport, R15, zport->regs[15]);

	/* Record the current state of RR0.  */
	zport->mctrl = zs_raw_get_mctrl(zport);
	zport->brk = read_zsreg(zport, R0) & BRK_ABRT;

	zport->tx_stopped = 1;

	spin_unlock_irqrestore(&scc->zlock, flags);

	return 0;
}

static void zs_shutdown(struct uart_port *uport)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;
	unsigned long flags;
	int irq_guard;

	spin_lock_irqsave(&scc->zlock, flags);

	zport->regs[5] &= ~TxENAB;
	zport->regs[3] &= ~RxENABLE;
	write_zsreg(zport, R5, zport->regs[5]);
	write_zsreg(zport, R3, zport->regs[3]);

	spin_unlock_irqrestore(&scc->zlock, flags);

	irq_guard = atomic_add_return(-1, &scc->irq_guard);
	if (!irq_guard)
		free_irq(zport->port.irq, scc);
}


static void zs_reset(struct zs_port *zport)
{
	struct zs_scc *scc = zport->scc;
	int irq;
	unsigned long flags;

	spin_lock_irqsave(&scc->zlock, flags);
	irq = !irqs_disabled_flags(flags);
	if (!scc->initialised) {
		/* Reset the pointer first, just in case...  */
		read_zsreg(zport, R0);
		/* And let the current transmission finish.  */
		zs_line_drain(zport, irq);
		write_zsreg(zport, R9, FHWRES);
		udelay(10);
		write_zsreg(zport, R9, 0);
		scc->initialised = 1;
	}
	load_zsregs(zport, zport->regs, irq);
	spin_unlock_irqrestore(&scc->zlock, flags);
}

static void zs_set_termios(struct uart_port *uport, struct ktermios *termios,
			   struct ktermios *old_termios)
{
	struct zs_port *zport = to_zport(uport);
	struct zs_scc *scc = zport->scc;
	struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
	int irq;
	unsigned int baud, brg;
	unsigned long flags;