Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1307 insertions, 0 deletions

diff --git a/drivers/tty/serial/zs.c b/drivers/tty/serial/zs.c
new file mode 100644
index 0000000000..65ca4da6e3
--- /dev/null
+++ b/drivers/tty/serial/zs.c
@@ -0,0 +1,1307 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * zs.c: Serial port driver for IOASIC DECstations.
+ *
+ * Derived from drivers/sbus/char/sunserial.c by Paul Mackerras.
+ * Derived from drivers/macintosh/macserial.c by Harald Koerfgen.
+ *
+ * DECstation changes
+ * Copyright (C) 1998-2000 Harald Koerfgen
+ * Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007  Maciej W. Rozycki
+ *
+ * For the rest of the code the original Copyright applies:
+ * Copyright (C) 1996 Paul Mackerras (Paul.Mackerras@cs.anu.edu.au)
+ * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
+ *
+ *
+ * Note: for IOASIC systems the wiring is as follows:
+ *
+ * mouse/keyboard:
+ * DIN-7 MJ-4  signal        SCC
+ * 2     1     TxD       <-  A.TxD
+ * 3     4     RxD       ->  A.RxD
+ *
+ * EIA-232/EIA-423:
+ * DB-25 MMJ-6 signal        SCC
+ * 2     2     TxD       <-  B.TxD
+ * 3     5     RxD       ->  B.RxD
+ * 4           RTS       <- ~A.RTS
+ * 5           CTS       -> ~B.CTS
+ * 6     6     DSR       -> ~A.SYNC
+ * 8           CD        -> ~B.DCD
+ * 12          DSRS(DCE) -> ~A.CTS  (*)
+ * 15          TxC       ->  B.TxC
+ * 17          RxC       ->  B.RxC
+ * 20    1     DTR       <- ~A.DTR
+ * 22          RI        -> ~A.DCD
+ * 23          DSRS(DTE) <- ~B.RTS
+ *
+ * (*) EIA-232 defines the signal at this pin to be SCD, while DSRS(DCE)
+ *     is shared with DSRS(DTE) at pin 23.
+ *
+ * As you can immediately notice the wiring of the RTS, DTR and DSR signals
+ * is a bit odd.  This makes the handling of port B unnecessarily
+ * complicated and prevents the use of some automatic modes of operation.
+ */
+
+#include <linux/bug.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/irqflags.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/major.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/spinlock.h>
+#include <linux/sysrq.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/types.h>
+
+#include <linux/atomic.h>
+
+#include <asm/dec/interrupts.h>
+#include <asm/dec/ioasic_addrs.h>
+#include <asm/dec/system.h>
+
+#include "zs.h"
+
+
+MODULE_AUTHOR("Maciej W. Rozycki <macro@linux-mips.org>");
+MODULE_DESCRIPTION("DECstation Z85C30 serial driver");
+MODULE_LICENSE("GPL");
+
+
+static char zs_name[] __initdata = "DECstation Z85C30 serial driver version ";
+static char zs_version[] __initdata = "0.10";
+
+/*
+ * It would be nice to dynamically allocate everything that
+ * depends on ZS_NUM_SCCS, so we could support any number of
+ * Z85C30s, but for now...
+ */
+#define ZS_NUM_SCCS	2		/* Max # of ZS chips supported.  */
+#define ZS_NUM_CHAN	2		/* 2 channels per chip.  */
+#define ZS_CHAN_A	0		/* Index of the channel A.  */
+#define ZS_CHAN_B	1		/* Index of the channel B.  */
+#define ZS_CHAN_IO_SIZE 8		/* IOMEM space size.  */
+#define ZS_CHAN_IO_STRIDE 4		/* Register alignment.  */
+#define ZS_CHAN_IO_OFFSET 1		/* The SCC resides on the high byte
+					   of the 16-bit IOBUS.  */
+#define ZS_CLOCK        7372800 	/* Z85C30 PCLK input clock rate.  */
+
+#define to_zport(uport) container_of(uport, struct zs_port, port)
+
+struct zs_parms {
+	resource_size_t scc[ZS_NUM_SCCS];
+	int irq[ZS_NUM_SCCS];
+};
+
+static struct zs_scc zs_sccs[ZS_NUM_SCCS];
+
+static u8 zs_init_regs[ZS_NUM_REGS] __initdata = {
+	0,				/* write 0 */
+	PAR_SPEC,			/* write 1 */
+	0,				/* write 2 */
+	0,				/* write 3 */
+	X16CLK | SB1,			/* write 4 */
+	0,				/* write 5 */
+	0, 0, 0,			/* write 6, 7, 8 */
+	MIE | DLC | NV,			/* write 9 */
+	NRZ,				/* write 10 */
+	TCBR | RCBR,			/* write 11 */
+	0, 0,				/* BRG time constant, write 12 + 13 */
+	BRSRC | BRENABL,		/* write 14 */
+	0,				/* write 15 */
+};
+
+/*
+ * Debugging.
+ */
+#undef ZS_DEBUG_REGS
+
+
+/*
+ * Reading and writing Z85C30 registers.
+ */
+static void recovery_delay(void)
+{
+	udelay(2);
+}
+
+static u8 read_zsreg(struct zs_port *zport, int reg)
+{
+	void __iomem *control = zport->port.membase + ZS_CHAN_IO_OFFSET;
+	u8 retval;
+
+	if (reg != 0) {
+		writeb(reg & 0xf, control);
+		fast_iob();
+		recovery_delay();
+	}
+	retval = readb(control);
+	recovery_delay();
+	return retval;
+}
+
+static void write_zsreg(struct zs_port *zport, int reg, u8 value)
+{
+	void __iomem *control = zport->port.membase + ZS_CHAN_IO_OFFSET;
+
+	if (reg != 0) {
+		writeb(reg & 0xf, control);
+		fast_iob(); recovery_delay();
+	}
+	writeb(value, control);
+	fast_iob();
+	recovery_delay();
+	return;
+}
+
+static u8 read_zsdata(struct zs_port *zport)
+{
+	void __iomem *data = zport->port.membase +
+			     ZS_CHAN_IO_STRIDE + ZS_CHAN_IO_OFFSET;
+	u8 retval;
+
+	retval = readb(data);
+	recovery_delay();
+	return retval;
+}
+
+static void write_zsdata(struct zs_port *zport, u8 value)
+{
+	void __iomem *data = zport->port.membase +
+			     ZS_CHAN_IO_STRIDE + ZS_CHAN_IO_OFFSET;
+
+	writeb(value, data);
+	fast_iob();
+	recovery_delay();
+	return;
+}
+
+#ifdef ZS_DEBUG_REGS
+void zs_dump(void)
+{
+	struct zs_port *zport;
+	int i, j;
+
+	for (i = 0; i < ZS_NUM_SCCS * ZS_NUM_CHAN; i++) {
+		zport = &zs_sccs[i / ZS_NUM_CHAN].zport[i % ZS_NUM_CHAN];
+
+		if (!zport->scc)
+			continue;
+
+		for (j = 0; j < 16; j++)
+			printk("W%-2d = 0x%02x\t", j, zport->regs[j]);
+		printk("\n");
+		for (j = 0; j < 16; j++)
+			printk("R%-2d = 0x%02x\t", j, read_zsreg(zport, j));
+		printk("\n\n");
+	}
+}
+#endif
+
+
+static void zs_spin_lock_cond_irq(spinlock_t *lock, int irq)
+{
+	if (irq)
+		spin_lock_irq(lock);
+	else
+		spin_lock(lock);
+}
+
+static void zs_spin_unlock_cond_irq(spinlock_t *lock, int irq)
+{
+	if (irq)
+		spin_unlock_irq(lock);
+	else
+		spin_unlock(lock);
+}
+
+static int zs_receive_drain(struct zs_port *zport)
+{
+	int loops = 10000;
+
+	while ((read_zsreg(zport, R0) & Rx_CH_AV) && --loops)
+		read_zsdata(zport);
+	return loops;
+}
+
+static int zs_transmit_drain(struct zs_port *zport, int irq)
+{
+	struct zs_scc *scc = zport->scc;
+	int loops = 10000;
+
+	while (!(read_zsreg(zport, R0) & Tx_BUF_EMP) && --loops) {
+		zs_spin_unlock_cond_irq(&scc->zlock, irq);
+		udelay(2);
+		zs_spin_lock_cond_irq(&scc->zlock, irq);
+	}
+	return loops;
+}
+
+static int zs_line_drain(struct zs_port *zport, int irq)
+{
+	struct zs_scc *scc = zport->scc;
+	int loops = 10000;
+
+	while (!(read_zsreg(zport, R1) & ALL_SNT) && --loops) {
+		zs_spin_unlock_cond_irq(&scc->zlock, irq);
+		udelay(2);
+		zs_spin_lock_cond_irq(&scc->zlock, irq);
+	}
+	return loops;
+}
+
+
+static void load_zsregs(struct zs_port *zport, u8 *regs, int irq)
+{
+	/* Let the current transmission finish.  */
+	zs_line_drain(zport, irq);
+	/* Load 'em up.  */
+	write_zsreg(zport, R3, regs[3] & ~RxENABLE);
+	write_zsreg(zport, R5, regs[5] & ~TxENAB);
+	write_zsreg(zport, R4, regs[4]);
+	write_zsreg(zport, R9, regs[9]);
+	write_zsreg(zport, R1, regs[1]);
+	write_zsreg(zport, R2, regs[2]);
+	write_zsreg(zport, R10, regs[10]);
+	write_zsreg(zport, R14, regs[14] & ~BRENABL);
+	write_zsreg(zport, R11, regs[11]);
+	write_zsreg(zport, R12, regs[12]);
+	write_zsreg(zport, R13, regs[13]);
+	write_zsreg(zport, R14, regs[14]);
+	write_zsreg(zport, R15, regs[15]);
+	if (regs[3] & RxENABLE)
+		write_zsreg(zport, R3, regs[3]);
+	if (regs[5] & TxENAB)
+		write_zsreg(zport, R5, regs[5]);
+	return;
+}
+
+
+/*
+ * Status handling routines.
+ */
+
+/*
+ * zs_tx_empty() -- get the transmitter empty status
+ *
+ * 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 unsigned int zs_tx_empty(struct uart_port *uport)
+{
+	struct zs_port *zport = to_zport(uport);
+	struct zs_scc *scc = zport->scc;
+	unsigned long flags;
+	u8 status;
+
+	spin_lock_irqsave(&scc->zlock, flags);
+	status = read_zsreg(zport, R1);
+	spin_unlock_irqrestore(&scc->zlock, flags);
+
+	return status & ALL_SNT ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int zs_raw_get_ab_mctrl(struct zs_port *zport_a,
+					struct zs_port *zport_b)
+{
+	u8 status_a, status_b;
+	unsigned int mctrl;
+
+	status_a = read_zsreg(zport_a, R0);
+	status_b = read_zsreg(zport_b, R0);
+
+	mctrl = ((status_b & CTS) ? TIOCM_CTS : 0) |
+		((status_b & DCD) ? TIOCM_CAR : 0) |
+		((status_a & DCD) ? TIOCM_RNG : 0) |
+		((status_a & SYNC_HUNT) ? TIOCM_DSR : 0);
+
+	return mctrl;
+}
+
+static unsigned int zs_raw_get_mctrl(struct zs_port *zport)
+{
+	struct zs_port *zport_a = &zport->scc->zport[ZS_CHAN_A];
+
+	return zport != zport_a ? zs_raw_get_ab_mctrl(zport_a, zport) : 0;
+}
+
+static unsigned int zs_raw_xor_mctrl(struct zs_port *zport)
+{
+	struct zs_port *zport_a = &zport->scc->zport[ZS_CHAN_A];
+	unsigned int mmask, mctrl, delta;
+	u8 mask_a, mask_b;
+
+	if (zport == zport_a)
+		return 0;
+
+	mask_a = zport_a->regs[15];
+	mask_b = zport->regs[15];
+
+	mmask = ((mask_b & CTSIE) ? TIOCM_CTS : 0) |
+		((mask_b & DCDIE) ? TIOCM_CAR : 0) |
+		((mask_a & DCDIE) ? TIOCM_RNG : 0) |
+		((mask_a & SYNCIE) ? TIOCM_DSR : 0);
+
+	mctrl = zport->mctrl;
+	if (mmask) {
+		mctrl &= ~mmask;
+		mctrl |= zs_raw_get_ab_mctrl(zport_a, zport) & mmask;
+	}
+
+	delta = mctrl ^ zport->mctrl;
+	if (delta)
+		zport->mctrl = mctrl;
+
+	return delta;
+}
+
+static unsigned int zs_get_mctrl(struct uart_port *uport)
+{
+	struct zs_port *zport = to_zport(uport);
+	struct zs_scc *scc = zport->scc;
+	unsigned int mctrl;
+
+	spin_lock(&scc->zlock);
+	mctrl = zs_raw_get_mctrl(zport);
+	spin_unlock(&scc->zlock);
+
+	return mctrl;
+}
+
+static void zs_set_mctrl(struct uart_port *uport, unsigned int mctrl)
+{
+	struct zs_port *zport = to_zport(uport);
+	struct zs_scc *scc = zport->scc;
+	struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
+	u8 oldloop, newloop;
+
+	spin_lock(&scc->zlock);
+	if (zport != zport_a) {
+		if (mctrl & TIOCM_DTR)
+			zport_a->regs[5] |= DTR;
+		else
+			zport_a->regs[5] &= ~DTR;
+		if (mctrl & TIOCM_RTS)
+			zport_a->regs[5] |= RTS;
+		else
+			zport_a->regs[5] &= ~RTS;
+		write_zsreg(zport_a, R5, zport_a->regs[5]);
+	}
+
+	/* Rarely modified, so don't poke at hardware unless necessary. */
+	oldloop = zport->regs[14];
+	newloop = oldloop;
+	if (mctrl & TIOCM_LOOP)
+		newloop |= LOOPBAK;
+	else
+		newloop &= ~LOOPBAK;
+	if (newloop != oldloop) {
+		zport->regs[14] = newloop;
+		write_zsreg(zport, R14, zport->regs[14]);
+	}
+	spin_unlock(&scc->zlock);
+}
+
+static void zs_raw_stop_tx(struct zs_port *zport)
+{
+	write_zsreg(zport, R0, RES_Tx_P);
+	zport->tx_stopped = 1;
+}
+
+static void zs_stop_tx(struct uart_port *uport)
+{
+	struct zs_port *zport = to_zport(uport);
+	struct zs_scc *scc = zport->scc;
+
+	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;
+	int count;
+	u8 ch, flag;
+
+	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->state->port);
+}
+
+static void zs_raw_transmit_chars(struct zs_port *zport)
+{
+	struct circ_buf *xmit = &zport->port.state->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]);
+	uart_xmit_advance(&zport->port, 1);
+
+	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->state->port.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[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[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,
+			   const 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;
+
+	spin_lock_irqsave(&scc->zlock, flags);
+	irq = !irqs_disabled_flags(flags);
+
+	/* Byte size.  */
+	zport->regs[3] &= ~RxNBITS_MASK;
+	zport->regs[5] &= ~TxNBITS_MASK;
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		zport->regs[3] |= Rx5;
+		zport->regs[5] |= Tx5;
+		break;
+	case CS6:
+		zport->regs[3] |= Rx6;
+		zport->regs[5] |= Tx6;
+		break;
+	case CS7:
+		zport->regs[3] |= Rx7;
+		zport->regs[5] |= Tx7;
+		break;
+	case CS8:
+	default:
+		zport->regs[3] |= Rx8;
+		zport->regs[5] |= Tx8;
+		break;
+	}
+
+	/* Parity and stop bits.  */
+	zport->regs[4] &= ~(XCLK_MASK | SB_MASK | PAR_ENA | PAR_EVEN);
+	if (termios->c_cflag & CSTOPB)
+		zport->regs[4] |= SB2;
+	else
+		zport->regs[4] |= SB1;
+	if (termios->c_cflag & PARENB)
+		zport->regs[4] |= PAR_ENA;
+	if (!(termios->c_cflag & PARODD))
+		zport->regs[4] |= PAR_EVEN;
+	switch (zport->clk_mode) {
+	case 64:
+		zport->regs[4] |= X64CLK;
+		break;
+	case 32:
+		zport->regs[4] |= X32CLK;
+		break;
+	case 16:
+		zport->regs[4] |= X16CLK;
+		break;
+	case 1:
+		zport->regs[4] |= X1CLK;
+		break;
+	default:
+		BUG();
+	}
+
+	baud = uart_get_baud_rate(uport, termios, old_termios, 0,
+				  uport->uartclk / zport->clk_mode / 4);
+
+	brg = ZS_BPS_TO_BRG(baud, uport->uartclk / zport->clk_mode);
+	zport->regs[12] = brg & 0xff;
+	zport->regs[13] = (brg >> 8) & 0xff;
+
+	uart_update_timeout(uport, termios->c_cflag, baud);
+
+	uport->read_status_mask = Rx_OVR;
+	if (termios->c_iflag & INPCK)
+		uport->read_status_mask |= FRM_ERR | PAR_ERR;
+	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
+		uport->read_status_mask |= Rx_BRK;
+
+	uport->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		uport->ignore_status_mask |= FRM_ERR | PAR_ERR;
+	if (termios->c_iflag & IGNBRK) {
+		uport->ignore_status_mask |= Rx_BRK;
+		if (termios->c_iflag & IGNPAR)
+			uport->ignore_status_mask |= Rx_OVR;
+	}
+
+	if (termios->c_cflag & CREAD)
+		zport->regs[3] |= RxENABLE;
+	else
+		zport->regs[3] &= ~RxENABLE;
+
+	if (zport != zport_a) {
+		if (!(termios->c_cflag & CLOCAL)) {
+			zport->regs[15] |= DCDIE;
+		} else
+			zport->regs[15] &= ~DCDIE;
+		if (termios->c_cflag & CRTSCTS) {
+			zport->regs[15] |= CTSIE;
+		} else
+			zport->regs[15] &= ~CTSIE;
+		zs_raw_xor_mctrl(zport);
+	}
+
+	/* Load up the new values.  */
+	load_zsregs(zport, zport->regs, irq);
+
+	spin_unlock_irqrestore(&scc->zlock, flags);
+}
+
+/*
+ * Hack alert!
+ * Required solely so that the initial PROM-based console
+ * works undisturbed in parallel with this one.
+ */
+static void zs_pm(struct uart_port *uport, unsigned int state,
+		  unsigned int oldstate)
+{
+	struct zs_port *zport = to_zport(uport);
+
+	if (state < 3)
+		zport->regs[5] |= TxENAB;
+	else
+		zport->regs[5] &= ~TxENAB;
+	write_zsreg(zport, R5, zport->regs[5]);
+}
+
+
+static const char *zs_type(struct uart_port *uport)
+{
+	return "Z85C30 SCC";
+}
+
+static void zs_release_port(struct uart_port *uport)
+{
+	iounmap(uport->membase);
+	uport->membase = NULL;
+	release_mem_region(uport->mapbase, ZS_CHAN_IO_SIZE);
+}
+
+static int zs_map_port(struct uart_port *uport)
+{
+	if (!uport->membase)
+		uport->membase = ioremap(uport->mapbase,
+						 ZS_CHAN_IO_SIZE);
+	if (!uport->membase) {
+		printk(KERN_ERR "zs: Cannot map MMIO\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static int zs_request_port(struct uart_port *uport)
+{
+	int ret;
+
+	if (!request_mem_region(uport->mapbase, ZS_CHAN_IO_SIZE, "scc")) {
+		printk(KERN_ERR "zs: Unable to reserve MMIO resource\n");
+		return -EBUSY;
+	}
+	ret = zs_map_port(uport);
+	if (ret) {
+		release_mem_region(uport->mapbase, ZS_CHAN_IO_SIZE);
+		return ret;
+	}
+	return 0;
+}
+
+static void zs_config_port(struct uart_port *uport, int flags)
+{
+	struct zs_port *zport = to_zport(uport);
+
+	if (flags & UART_CONFIG_TYPE) {
+		if (zs_request_port(uport))
+			return;
+
+		uport->type = PORT_ZS;
+
+		zs_reset(zport);
+	}
+}
+
+static int zs_verify_port(struct uart_port *uport, struct serial_struct *ser)
+{
+	struct zs_port *zport = to_zport(uport);
+	int ret = 0;
+
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_ZS)
+		ret = -EINVAL;
+	if (ser->irq != uport->irq)
+		ret = -EINVAL;
+	if (ser->baud_base != uport->uartclk / zport->clk_mode / 4)
+		ret = -EINVAL;
+	return ret;
+}
+
+
+static const struct uart_ops zs_ops = {
+	.tx_empty	= zs_tx_empty,
+	.set_mctrl	= zs_set_mctrl,
+	.get_mctrl	= zs_get_mctrl,
+	.stop_tx	= zs_stop_tx,
+	.start_tx	= zs_start_tx,
+	.stop_rx	= zs_stop_rx,
+	.enable_ms	= zs_enable_ms,
+	.break_ctl	= zs_break_ctl,
+	.startup	= zs_startup,
+	.shutdown	= zs_shutdown,
+	.set_termios	= zs_set_termios,
+	.pm		= zs_pm,
+	.type		= zs_type,
+	.release_port	= zs_release_port,
+	.request_port	= zs_request_port,
+	.config_port	= zs_config_port,
+	.verify_port	= zs_verify_port,
+};
+
+/*
+ * Initialize Z85C30 port structures.
+ */
+static int __init zs_probe_sccs(void)
+{
+	static int probed;
+	struct zs_parms zs_parms;
+	int chip, side, irq;
+	int n_chips = 0;
+	int i;
+
+	if (probed)
+		return 0;
+
+	irq = dec_interrupt[DEC_IRQ_SCC0];
+	if (irq >= 0) {
+		zs_parms.scc[n_chips] = IOASIC_SCC0;
+		zs_parms.irq[n_chips] = dec_interrupt[DEC_IRQ_SCC0];
+		n_chips++;
+	}
+	irq = dec_interrupt[DEC_IRQ_SCC1];
+	if (irq >= 0) {
+		zs_parms.scc[n_chips] = IOASIC_SCC1;
+		zs_parms.irq[n_chips] = dec_interrupt[DEC_IRQ_SCC1];
+		n_chips++;
+	}
+	if (!n_chips)
+		return -ENXIO;
+
+	probed = 1;
+
+	for (chip = 0; chip < n_chips; chip++) {
+		spin_lock_init(&zs_sccs[chip].zlock);
+		for (side = 0; side < ZS_NUM_CHAN; side++) {
+			struct zs_port *zport = &zs_sccs[chip].zport[side];
+			struct uart_port *uport = &zport->port;
+
+			zport->scc	= &zs_sccs[chip];
+			zport->clk_mode	= 16;
+
+			uport->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ZS_CONSOLE);
+			uport->irq	= zs_parms.irq[chip];
+			uport->uartclk	= ZS_CLOCK;
+			uport->fifosize	= 1;
+			uport->iotype	= UPIO_MEM;
+			uport->flags	= UPF_BOOT_AUTOCONF;
+			uport->ops	= &zs_ops;
+			uport->line	= chip * ZS_NUM_CHAN + side;
+			uport->mapbase	= dec_kn_slot_base +
+					  zs_parms.scc[chip] +
+					  (side ^ ZS_CHAN_B) * ZS_CHAN_IO_SIZE;
+
+			for (i = 0; i < ZS_NUM_REGS; i++)
+				zport->regs[i] = zs_init_regs[i];
+		}
+	}
+
+	return 0;
+}
+
+
+#ifdef CONFIG_SERIAL_ZS_CONSOLE
+static void zs_console_putchar(struct uart_port *uport, unsigned char ch)
+{
+	struct zs_port *zport = to_zport(uport);
+	struct zs_scc *scc = zport->scc;
+	int irq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&scc->zlock, flags);
+	irq = !irqs_disabled_flags(flags);
+	if (zs_transmit_drain(zport, irq))
+		write_zsdata(zport, ch);
+	spin_unlock_irqrestore(&scc->zlock, flags);
+}
+
+/*
+ * Print a string to the serial port trying not to disturb
+ * any possible real use of the port...
+ */
+static void zs_console_write(struct console *co, const char *s,
+			     unsigned int count)
+{
+	int chip = co->index / ZS_NUM_CHAN, side = co->index % ZS_NUM_CHAN;
+	struct zs_port *zport = &zs_sccs[chip].zport[side];
+	struct zs_scc *scc = zport->scc;
+	unsigned long flags;
+	u8 txint, txenb;
+	int irq;
+
+	/* Disable transmit interrupts and enable the transmitter. */
+	spin_lock_irqsave(&scc->zlock, flags);
+	txint = zport->regs[1];
+	txenb = zport->regs[5];
+	if (txint & TxINT_ENAB) {
+		zport->regs[1] = txint & ~TxINT_ENAB;
+		write_zsreg(zport, R1, zport->regs[1]);
+	}
+	if (!(txenb & TxENAB)) {
+		zport->regs[5] = txenb | TxENAB;
+		write_zsreg(zport, R5, zport->regs[5]);
+	}
+	spin_unlock_irqrestore(&scc->zlock, flags);
+
+	uart_console_write(&zport->port, s, count, zs_console_putchar);
+
+	/* Restore transmit interrupts and the transmitter enable. */
+	spin_lock_irqsave(&scc->zlock, flags);
+	irq = !irqs_disabled_flags(flags);
+	zs_line_drain(zport, irq);
+	if (!(txenb & TxENAB)) {
+		zport->regs[5] &= ~TxENAB;
+		write_zsreg(zport, R5, zport->regs[5]);
+	}
+	if (txint & TxINT_ENAB) {
+		zport->regs[1] |= TxINT_ENAB;
+		write_zsreg(zport, R1, zport->regs[1]);
+
+		/* Resume any transmission as the TxIP bit won't be set.  */
+		if (!zport->tx_stopped)
+			zs_raw_transmit_chars(zport);
+	}
+	spin_unlock_irqrestore(&scc->zlock, flags);
+}
+
+/*
+ * Setup serial console baud/bits/parity.  We do two things here:
+ * - construct a cflag setting for the first uart_open()
+ * - initialise the serial port
+ * Return non-zero if we didn't find a serial port.
+ */
+static int __init zs_console_setup(struct console *co, char *options)
+{
+	int chip = co->index / ZS_NUM_CHAN, side = co->index % ZS_NUM_CHAN;
+	struct zs_port *zport = &zs_sccs[chip].zport[side];
+	struct uart_port *uport = &zport->port;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+	int ret;
+
+	ret = zs_map_port(uport);
+	if (ret)
+		return ret;
+
+	zs_reset(zport);
+	zs_pm(uport, 0, -1);
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+	return uart_set_options(uport, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver zs_reg;
+static struct console zs_console = {
+	.name	= "ttyS",
+	.write	= zs_console_write,
+	.device	= uart_console_device,
+	.setup	= zs_console_setup,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1,
+	.data	= &zs_reg,
+};
+
+/*
+ *	Register console.
+ */
+static int __init zs_serial_console_init(void)
+{
+	int ret;
+
+	ret = zs_probe_sccs();
+	if (ret)
+		return ret;
+	register_console(&zs_console);
+
+	return 0;
+}
+
+console_initcall(zs_serial_console_init);
+
+#define SERIAL_ZS_CONSOLE	&zs_console
+#else
+#define SERIAL_ZS_CONSOLE	NULL
+#endif /* CONFIG_SERIAL_ZS_CONSOLE */
+
+static struct uart_driver zs_reg = {
+	.owner			= THIS_MODULE,
+	.driver_name		= "serial",
+	.dev_name		= "ttyS",
+	.major			= TTY_MAJOR,
+	.minor			= 64,
+	.nr			= ZS_NUM_SCCS * ZS_NUM_CHAN,
+	.cons			= SERIAL_ZS_CONSOLE,
+};
+
+/* zs_init inits the driver. */
+static int __init zs_init(void)
+{
+	int i, ret;
+
+	pr_info("%s%s\n", zs_name, zs_version);
+
+	/* Find out how many Z85C30 SCCs we have.  */
+	ret = zs_probe_sccs();
+	if (ret)
+		return ret;
+
+	ret = uart_register_driver(&zs_reg);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ZS_NUM_SCCS * ZS_NUM_CHAN; i++) {
+		struct zs_scc *scc = &zs_sccs[i / ZS_NUM_CHAN];
+		struct zs_port *zport = &scc->zport[i % ZS_NUM_CHAN];
+		struct uart_port *uport = &zport->port;
+
+		if (zport->scc)
+			uart_add_one_port(&zs_reg, uport);
+	}
+
+	return 0;
+}
+
+static void __exit zs_exit(void)
+{
+	int i;
+
+	for (i = ZS_NUM_SCCS * ZS_NUM_CHAN - 1; i >= 0; i--) {
+		struct zs_scc *scc = &zs_sccs[i / ZS_NUM_CHAN];
+		struct zs_port *zport = &scc->zport[i % ZS_NUM_CHAN];
+		struct uart_port *uport = &zport->port;
+
+		if (zport->scc)
+			uart_remove_one_port(&zs_reg, uport);
+	}
+
+	uart_unregister_driver(&zs_reg);
+}
+
+module_init(zs_init);
+module_exit(zs_exit);