Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1271 insertions, 0 deletions

diff --git a/drivers/serial/ip22zilog.c b/drivers/serial/ip22zilog.c
new file mode 100644
index 000000000000..3ea46c069f6f
--- /dev/null
+++ b/drivers/serial/ip22zilog.c
@@ -0,0 +1,1271 @@
+/*
+ * Driver for Zilog serial chips found on SGI workstations and
+ * servers.  This driver could actually be made more generic.
+ *
+ * This is based on the drivers/serial/sunzilog.c code as of 2.6.0-test7 and the
+ * old drivers/sgi/char/sgiserial.c code which itself is based of the original
+ * drivers/sbus/char/zs.c code.  A lot of code has been simply moved over
+ * directly from there but much has been rewritten.  Credits therefore go out
+ * to David S. Miller, Eddie C. Dost, Pete Zaitcev, Ted Ts'o and Alex Buell
+ * for their work there.
+ *
+ *  Copyright (C) 2002 Ralf Baechle (ralf@linux-mips.org)
+ *  Copyright (C) 2002 David S. Miller (davem@redhat.com)
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/major.h>
+#include <linux/string.h>
+#include <linux/ptrace.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/circ_buf.h>
+#include <linux/serial.h>
+#include <linux/sysrq.h>
+#include <linux/console.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/sgialib.h>
+#include <asm/sgi/ioc.h>
+#include <asm/sgi/hpc3.h>
+#include <asm/sgi/ip22.h>
+
+#if defined(CONFIG_SERIAL_IP22_ZILOG_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/serial_core.h>
+
+#include "ip22zilog.h"
+
+void ip22_do_break(void);
+
+/*
+ * On IP22 we need to delay after register accesses but we do not need to
+ * flush writes.
+ */
+#define ZSDELAY()		udelay(5)
+#define ZSDELAY_LONG()		udelay(20)
+#define ZS_WSYNC(channel)	do { } while (0)
+
+#define NUM_IP22ZILOG		1
+#define NUM_CHANNELS		(NUM_IP22ZILOG * 2)
+
+#define ZS_CLOCK		3672000	/* Zilog input clock rate. */
+#define ZS_CLOCK_DIVISOR	16      /* Divisor this driver uses. */
+
+/*
+ * We wrap our port structure around the generic uart_port.
+ */
+struct uart_ip22zilog_port {
+	struct uart_port		port;
+
+	/* IRQ servicing chain.  */
+	struct uart_ip22zilog_port	*next;
+
+	/* Current values of Zilog write registers.  */
+	unsigned char			curregs[NUM_ZSREGS];
+
+	unsigned int			flags;
+#define IP22ZILOG_FLAG_IS_CONS		0x00000004
+#define IP22ZILOG_FLAG_IS_KGDB		0x00000008
+#define IP22ZILOG_FLAG_MODEM_STATUS	0x00000010
+#define IP22ZILOG_FLAG_IS_CHANNEL_A	0x00000020
+#define IP22ZILOG_FLAG_REGS_HELD	0x00000040
+#define IP22ZILOG_FLAG_TX_STOPPED	0x00000080
+#define IP22ZILOG_FLAG_TX_ACTIVE	0x00000100
+
+	unsigned int			cflag;
+
+	/* L1-A keyboard break state.  */
+	int				kbd_id;
+	int				l1_down;
+
+	unsigned char			parity_mask;
+	unsigned char			prev_status;
+};
+
+#define ZILOG_CHANNEL_FROM_PORT(PORT)	((struct zilog_channel *)((PORT)->membase))
+#define UART_ZILOG(PORT)		((struct uart_ip22zilog_port *)(PORT))
+#define IP22ZILOG_GET_CURR_REG(PORT, REGNUM)		\
+	(UART_ZILOG(PORT)->curregs[REGNUM])
+#define IP22ZILOG_SET_CURR_REG(PORT, REGNUM, REGVAL)	\
+	((UART_ZILOG(PORT)->curregs[REGNUM]) = (REGVAL))
+#define ZS_IS_CONS(UP)	((UP)->flags & IP22ZILOG_FLAG_IS_CONS)
+#define ZS_IS_KGDB(UP)	((UP)->flags & IP22ZILOG_FLAG_IS_KGDB)
+#define ZS_WANTS_MODEM_STATUS(UP)	((UP)->flags & IP22ZILOG_FLAG_MODEM_STATUS)
+#define ZS_IS_CHANNEL_A(UP)	((UP)->flags & IP22ZILOG_FLAG_IS_CHANNEL_A)
+#define ZS_REGS_HELD(UP)	((UP)->flags & IP22ZILOG_FLAG_REGS_HELD)
+#define ZS_TX_STOPPED(UP)	((UP)->flags & IP22ZILOG_FLAG_TX_STOPPED)
+#define ZS_TX_ACTIVE(UP)	((UP)->flags & IP22ZILOG_FLAG_TX_ACTIVE)
+
+/* Reading and writing Zilog8530 registers.  The delays are to make this
+ * driver work on the IP22 which needs a settling delay after each chip
+ * register access, other machines handle this in hardware via auxiliary
+ * flip-flops which implement the settle time we do in software.
+ *
+ * The port lock must be held and local IRQs must be disabled
+ * when {read,write}_zsreg is invoked.
+ */
+static unsigned char read_zsreg(struct zilog_channel *channel,
+				unsigned char reg)
+{
+	unsigned char retval;
+
+	writeb(reg, &channel->control);
+	ZSDELAY();
+	retval = readb(&channel->control);
+	ZSDELAY();
+
+	return retval;
+}
+
+static void write_zsreg(struct zilog_channel *channel,
+			unsigned char reg, unsigned char value)
+{
+	writeb(reg, &channel->control);
+	ZSDELAY();
+	writeb(value, &channel->control);
+	ZSDELAY();
+}
+
+static void ip22zilog_clear_fifo(struct zilog_channel *channel)
+{
+	int i;
+
+	for (i = 0; i < 32; i++) {
+		unsigned char regval;
+
+		regval = readb(&channel->control);
+		ZSDELAY();
+		if (regval & Rx_CH_AV)
+			break;
+
+		regval = read_zsreg(channel, R1);
+		readb(&channel->data);
+		ZSDELAY();
+
+		if (regval & (PAR_ERR | Rx_OVR | CRC_ERR)) {
+			writeb(ERR_RES, &channel->control);
+			ZSDELAY();
+			ZS_WSYNC(channel);
+		}
+	}
+}
+
+/* This function must only be called when the TX is not busy.  The UART
+ * port lock must be held and local interrupts disabled.
+ */
+static void __load_zsregs(struct zilog_channel *channel, unsigned char *regs)
+{
+	int i;
+
+	/* Let pending transmits finish.  */
+	for (i = 0; i < 1000; i++) {
+		unsigned char stat = read_zsreg(channel, R1);
+		if (stat & ALL_SNT)
+			break;
+		udelay(100);
+	}
+
+	writeb(ERR_RES, &channel->control);
+	ZSDELAY();
+	ZS_WSYNC(channel);
+
+	ip22zilog_clear_fifo(channel);
+
+	/* Disable all interrupts.  */
+	write_zsreg(channel, R1,
+		    regs[R1] & ~(RxINT_MASK | TxINT_ENAB | EXT_INT_ENAB));
+
+	/* Set parity, sync config, stop bits, and clock divisor.  */
+	write_zsreg(channel, R4, regs[R4]);
+
+	/* Set misc. TX/RX control bits.  */
+	write_zsreg(channel, R10, regs[R10]);
+
+	/* Set TX/RX controls sans the enable bits.  */
+	write_zsreg(channel, R3, regs[R3] & ~RxENAB);
+	write_zsreg(channel, R5, regs[R5] & ~TxENAB);
+
+	/* Synchronous mode config.  */
+	write_zsreg(channel, R6, regs[R6]);
+	write_zsreg(channel, R7, regs[R7]);
+
+	/* Don't mess with the interrupt vector (R2, unused by us) and
+	 * master interrupt control (R9).  We make sure this is setup
+	 * properly at probe time then never touch it again.
+	 */
+
+	/* Disable baud generator.  */
+	write_zsreg(channel, R14, regs[R14] & ~BRENAB);
+
+	/* Clock mode control.  */
+	write_zsreg(channel, R11, regs[R11]);
+
+	/* Lower and upper byte of baud rate generator divisor.  */
+	write_zsreg(channel, R12, regs[R12]);
+	write_zsreg(channel, R13, regs[R13]);
+	
+	/* Now rewrite R14, with BRENAB (if set).  */
+	write_zsreg(channel, R14, regs[R14]);
+
+	/* External status interrupt control.  */
+	write_zsreg(channel, R15, regs[R15]);
+
+	/* Reset external status interrupts.  */
+	write_zsreg(channel, R0, RES_EXT_INT);
+	write_zsreg(channel, R0, RES_EXT_INT);
+
+	/* Rewrite R3/R5, this time without enables masked.  */
+	write_zsreg(channel, R3, regs[R3]);
+	write_zsreg(channel, R5, regs[R5]);
+
+	/* Rewrite R1, this time without IRQ enabled masked.  */
+	write_zsreg(channel, R1, regs[R1]);
+}
+
+/* Reprogram the Zilog channel HW registers with the copies found in the
+ * software state struct.  If the transmitter is busy, we defer this update
+ * until the next TX complete interrupt.  Else, we do it right now.
+ *
+ * The UART port lock must be held and local interrupts disabled.
+ */
+static void ip22zilog_maybe_update_regs(struct uart_ip22zilog_port *up,
+				       struct zilog_channel *channel)
+{
+	if (!ZS_REGS_HELD(up)) {
+		if (ZS_TX_ACTIVE(up)) {
+			up->flags |= IP22ZILOG_FLAG_REGS_HELD;
+		} else {
+			__load_zsregs(channel, up->curregs);
+		}
+	}
+}
+
+static void ip22zilog_receive_chars(struct uart_ip22zilog_port *up,
+				   struct zilog_channel *channel,
+				   struct pt_regs *regs)
+{
+	struct tty_struct *tty = up->port.info->tty;	/* XXX info==NULL? */
+
+	while (1) {
+		unsigned char ch, r1;
+
+		if (unlikely(tty->flip.count >= TTY_FLIPBUF_SIZE)) {
+			tty->flip.work.func((void *)tty);
+			if (tty->flip.count >= TTY_FLIPBUF_SIZE)
+				return;		/* XXX Ignores SysRq when we need it most. Fix. */
+		}
+
+		r1 = read_zsreg(channel, R1);
+		if (r1 & (PAR_ERR | Rx_OVR | CRC_ERR)) {
+			writeb(ERR_RES, &channel->control);
+			ZSDELAY();
+			ZS_WSYNC(channel);
+		}
+
+		ch = readb(&channel->control);
+		ZSDELAY();
+
+		/* This funny hack depends upon BRK_ABRT not interfering
+		 * with the other bits we care about in R1.
+		 */
+		if (ch & BRK_ABRT)
+			r1 |= BRK_ABRT;
+
+		ch = readb(&channel->data);
+		ZSDELAY();
+
+		ch &= up->parity_mask;
+
+		if (ZS_IS_CONS(up) && (r1 & BRK_ABRT)) {
+			/* Wait for BREAK to deassert to avoid potentially
+			 * confusing the PROM.
+			 */
+			while (1) {
+				ch = readb(&channel->control);
+				ZSDELAY();
+				if (!(ch & BRK_ABRT))
+					break;
+			}
+			ip22_do_break();
+			return;
+		}
+
+		/* A real serial line, record the character and status.  */
+		*tty->flip.char_buf_ptr = ch;
+		*tty->flip.flag_buf_ptr = TTY_NORMAL;
+		up->port.icount.rx++;
+		if (r1 & (BRK_ABRT | PAR_ERR | Rx_OVR | CRC_ERR)) {
+			if (r1 & BRK_ABRT) {
+				r1 &= ~(PAR_ERR | CRC_ERR);
+				up->port.icount.brk++;
+				if (uart_handle_break(&up->port))
+					goto next_char;
+			}
+			else if (r1 & PAR_ERR)
+				up->port.icount.parity++;
+			else if (r1 & CRC_ERR)
+				up->port.icount.frame++;
+			if (r1 & Rx_OVR)
+				up->port.icount.overrun++;
+			r1 &= up->port.read_status_mask;
+			if (r1 & BRK_ABRT)
+				*tty->flip.flag_buf_ptr = TTY_BREAK;
+			else if (r1 & PAR_ERR)
+				*tty->flip.flag_buf_ptr = TTY_PARITY;
+			else if (r1 & CRC_ERR)
+				*tty->flip.flag_buf_ptr = TTY_FRAME;
+		}
+		if (uart_handle_sysrq_char(&up->port, ch, regs))
+			goto next_char;
+
+		if (up->port.ignore_status_mask == 0xff ||
+		    (r1 & up->port.ignore_status_mask) == 0) {
+			tty->flip.flag_buf_ptr++;
+			tty->flip.char_buf_ptr++;
+			tty->flip.count++;
+		}
+		if ((r1 & Rx_OVR) &&
+		    tty->flip.count < TTY_FLIPBUF_SIZE) {
+			*tty->flip.flag_buf_ptr = TTY_OVERRUN;
+			tty->flip.flag_buf_ptr++;
+			tty->flip.char_buf_ptr++;
+			tty->flip.count++;
+		}
+	next_char:
+		ch = readb(&channel->control);
+		ZSDELAY();
+		if (!(ch & Rx_CH_AV))
+			break;
+	}
+
+	tty_flip_buffer_push(tty);
+}
+
+static void ip22zilog_status_handle(struct uart_ip22zilog_port *up,
+				   struct zilog_channel *channel,
+				   struct pt_regs *regs)
+{
+	unsigned char status;
+
+	status = readb(&channel->control);
+	ZSDELAY();
+
+	writeb(RES_EXT_INT, &channel->control);
+	ZSDELAY();
+	ZS_WSYNC(channel);
+
+	if (ZS_WANTS_MODEM_STATUS(up)) {
+		if (status & SYNC)
+			up->port.icount.dsr++;
+
+		/* The Zilog just gives us an interrupt when DCD/CTS/etc. change.
+		 * But it does not tell us which bit has changed, we have to keep
+		 * track of this ourselves.
+		 */
+		if ((status & DCD) ^ up->prev_status)
+			uart_handle_dcd_change(&up->port,
+					       (status & DCD));
+		if ((status & CTS) ^ up->prev_status)
+			uart_handle_cts_change(&up->port,
+					       (status & CTS));
+
+		wake_up_interruptible(&up->port.info->delta_msr_wait);
+	}
+
+	up->prev_status = status;
+}
+
+static void ip22zilog_transmit_chars(struct uart_ip22zilog_port *up,
+				    struct zilog_channel *channel)
+{
+	struct circ_buf *xmit;
+
+	if (ZS_IS_CONS(up)) {
+		unsigned char status = readb(&channel->control);
+		ZSDELAY();
+
+		/* TX still busy?  Just wait for the next TX done interrupt.
+		 *
+		 * It can occur because of how we do serial console writes.  It would
+		 * be nice to transmit console writes just like we normally would for
+		 * a TTY line. (ie. buffered and TX interrupt driven).  That is not
+		 * easy because console writes cannot sleep.  One solution might be
+		 * to poll on enough port->xmit space becomming free.  -DaveM
+		 */
+		if (!(status & Tx_BUF_EMP))
+			return;
+	}
+
+	up->flags &= ~IP22ZILOG_FLAG_TX_ACTIVE;
+
+	if (ZS_REGS_HELD(up)) {
+		__load_zsregs(channel, up->curregs);
+		up->flags &= ~IP22ZILOG_FLAG_REGS_HELD;
+	}
+
+	if (ZS_TX_STOPPED(up)) {
+		up->flags &= ~IP22ZILOG_FLAG_TX_STOPPED;
+		goto ack_tx_int;
+	}
+
+	if (up->port.x_char) {
+		up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
+		writeb(up->port.x_char, &channel->data);
+		ZSDELAY();
+		ZS_WSYNC(channel);
+
+		up->port.icount.tx++;
+		up->port.x_char = 0;
+		return;
+	}
+
+	if (up->port.info == NULL)
+		goto ack_tx_int;
+	xmit = &up->port.info->xmit;
+	if (uart_circ_empty(xmit)) {
+		uart_write_wakeup(&up->port);
+		goto ack_tx_int;
+	}
+	if (uart_tx_stopped(&up->port))
+		goto ack_tx_int;
+
+	up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
+	writeb(xmit->buf[xmit->tail], &channel->data);
+	ZSDELAY();
+	ZS_WSYNC(channel);
+
+	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+	up->port.icount.tx++;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&up->port);
+
+	return;
+
+ack_tx_int:
+	writeb(RES_Tx_P, &channel->control);
+	ZSDELAY();
+	ZS_WSYNC(channel);
+}
+
+static irqreturn_t ip22zilog_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct uart_ip22zilog_port *up = dev_id;
+
+	while (up) {
+		struct zilog_channel *channel
+			= ZILOG_CHANNEL_FROM_PORT(&up->port);
+		unsigned char r3;
+
+		spin_lock(&up->port.lock);
+		r3 = read_zsreg(channel, R3);
+
+		/* Channel A */
+		if (r3 & (CHAEXT | CHATxIP | CHARxIP)) {
+			writeb(RES_H_IUS, &channel->control);
+			ZSDELAY();
+			ZS_WSYNC(channel);
+
+			if (r3 & CHARxIP)
+				ip22zilog_receive_chars(up, channel, regs);
+			if (r3 & CHAEXT)
+				ip22zilog_status_handle(up, channel, regs);
+			if (r3 & CHATxIP)
+				ip22zilog_transmit_chars(up, channel);
+		}
+		spin_unlock(&up->port.lock);
+
+		/* Channel B */
+		up = up->next;
+		channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+
+		spin_lock(&up->port.lock);
+		if (r3 & (CHBEXT | CHBTxIP | CHBRxIP)) {
+			writeb(RES_H_IUS, &channel->control);
+			ZSDELAY();
+			ZS_WSYNC(channel);
+
+			if (r3 & CHBRxIP)
+				ip22zilog_receive_chars(up, channel, regs);
+			if (r3 & CHBEXT)
+				ip22zilog_status_handle(up, channel, regs);
+			if (r3 & CHBTxIP)
+				ip22zilog_transmit_chars(up, channel);
+		}
+		spin_unlock(&up->port.lock);
+
+		up = up->next;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/* A convenient way to quickly get R0 status.  The caller must _not_ hold the
+ * port lock, it is acquired here.
+ */
+static __inline__ unsigned char ip22zilog_read_channel_status(struct uart_port *port)
+{
+	struct zilog_channel *channel;
+	unsigned long flags;
+	unsigned char status;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	channel = ZILOG_CHANNEL_FROM_PORT(port);
+	status = readb(&channel->control);
+	ZSDELAY();
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return status;
+}
+
+/* The port lock is not held.  */
+static unsigned int ip22zilog_tx_empty(struct uart_port *port)
+{
+	unsigned char status;
+	unsigned int ret;
+
+	status = ip22zilog_read_channel_status(port);
+	if (status & Tx_BUF_EMP)
+		ret = TIOCSER_TEMT;
+	else
+		ret = 0;
+
+	return ret;
+}
+
+/* The port lock is not held.  */
+static unsigned int ip22zilog_get_mctrl(struct uart_port *port)
+{
+	unsigned char status;
+	unsigned int ret;
+
+	status = ip22zilog_read_channel_status(port);
+
+	ret = 0;
+	if (status & DCD)
+		ret |= TIOCM_CAR;
+	if (status & SYNC)
+		ret |= TIOCM_DSR;
+	if (status & CTS)
+		ret |= TIOCM_CTS;
+
+	return ret;
+}
+
+/* The port lock is held and interrupts are disabled.  */
+static void ip22zilog_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
+	unsigned char set_bits, clear_bits;
+
+	set_bits = clear_bits = 0;
+
+	if (mctrl & TIOCM_RTS)
+		set_bits |= RTS;
+	else
+		clear_bits |= RTS;
+	if (mctrl & TIOCM_DTR)
+		set_bits |= DTR;
+	else
+		clear_bits |= DTR;
+
+	/* NOTE: Not subject to 'transmitter active' rule.  */ 
+	up->curregs[R5] |= set_bits;
+	up->curregs[R5] &= ~clear_bits;
+	write_zsreg(channel, R5, up->curregs[R5]);
+}
+
+/* The port lock is held and interrupts are disabled.  */
+static void ip22zilog_stop_tx(struct uart_port *port, unsigned int tty_stop)
+{
+	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+
+	up->flags |= IP22ZILOG_FLAG_TX_STOPPED;
+}
+
+/* The port lock is held and interrupts are disabled.  */
+static void ip22zilog_start_tx(struct uart_port *port, unsigned int tty_start)
+{
+	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
+	unsigned char status;
+
+	up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
+	up->flags &= ~IP22ZILOG_FLAG_TX_STOPPED;
+
+	status = readb(&channel->control);
+	ZSDELAY();
+
+	/* TX busy?  Just wait for the TX done interrupt.  */
+	if (!(status & Tx_BUF_EMP))
+		return;
+
+	/* Send the first character to jump-start the TX done
+	 * IRQ sending engine.
+	 */
+	if (port->x_char) {
+		writeb(port->x_char, &channel->data);
+		ZSDELAY();
+		ZS_WSYNC(channel);
+
+		port->icount.tx++;
+		port->x_char = 0;
+	} else {
+		struct circ_buf *xmit = &port->info->xmit;
+
+		writeb(xmit->buf[xmit->tail], &channel->data);
+		ZSDELAY();
+		ZS_WSYNC(channel);
+
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+
+		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+			uart_write_wakeup(&up->port);
+	}
+}
+
+/* The port lock is held and interrupts are disabled.  */
+static void ip22zilog_stop_rx(struct uart_port *port)
+{
+	struct uart_ip22zilog_port *up = UART_ZILOG(port);
+	struct zilog_channel *channel;
+
+	if (ZS_IS_CONS(up))
+		return;
+
+	channel = ZILOG_CHANNEL_FROM_PORT(port);
+
+	/* Disable all RX interrupts.  */
+	up->curregs[R1] &= ~RxINT_MASK;
+	ip22zilog_maybe_update_regs(up, channel);
+}
+
+/* The port lock is held.  */
+static void ip22zilog_enable_ms(struct uart_port *port)
+{
+	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
+	unsigned char new_reg;
+
+	new_reg = up->curregs[R15] | (DCDIE | SYNCIE | CTSIE);
+	if (new_reg != up->curregs[R15]) {
+		up->curregs[R15] = new_reg;
+
+		/* NOTE: Not subject to 'transmitter active' rule.  */ 
+		write_zsreg(channel, R15, up->curregs[R15]);
+	}
+}
+
+/* The port lock is not held.  */
+static void ip22zilog_break_ctl(struct uart_port *port, int break_state)
+{
+	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
+	unsigned char set_bits, clear_bits, new_reg;
+	unsigned long flags;
+
+	set_bits = clear_bits = 0;
+
+	if (break_state)
+		set_bits |= SND_BRK;
+	else
+		clear_bits |= SND_BRK;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	new_reg = (up->curregs[R5] | set_bits) & ~clear_bits;
+	if (new_reg != up->curregs[R5]) {
+		up->curregs[R5] = new_reg;
+
+		/* NOTE: Not subject to 'transmitter active' rule.  */ 
+		write_zsreg(channel, R5, up->curregs[R5]);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void __ip22zilog_startup(struct uart_ip22zilog_port *up)
+{
+	struct zilog_channel *channel;
+
+	channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+	up->prev_status = readb(&channel->control);
+
+	/* Enable receiver and transmitter.  */
+	up->curregs[R3] |= RxENAB;
+	up->curregs[R5] |= TxENAB;
+
+	up->curregs[R1] |= EXT_INT_ENAB | INT_ALL_Rx | TxINT_ENAB;
+	ip22zilog_maybe_update_regs(up, channel);
+}
+
+static int ip22zilog_startup(struct uart_port *port)
+{
+	struct uart_ip22zilog_port *up = UART_ZILOG(port);
+	unsigned long flags;
+
+	if (ZS_IS_CONS(up))
+		return 0;
+
+	spin_lock_irqsave(&port->lock, flags);
+	__ip22zilog_startup(up);
+	spin_unlock_irqrestore(&port->lock, flags);
+	return 0;
+}
+
+/*
+ * The test for ZS_IS_CONS is explained by the following e-mail:
+ *****
+ * From: Russell King <rmk@arm.linux.org.uk>
+ * Date: Sun, 8 Dec 2002 10:18:38 +0000
+ *
+ * On Sun, Dec 08, 2002 at 02:43:36AM -0500, Pete Zaitcev wrote:
+ * > I boot my 2.5 boxes using "console=ttyS0,9600" argument,
+ * > and I noticed that something is not right with reference
+ * > counting in this case. It seems that when the console
+ * > is open by kernel initially, this is not accounted
+ * > as an open, and uart_startup is not called.
+ *
+ * That is correct.  We are unable to call uart_startup when the serial
+ * console is initialised because it may need to allocate memory (as
+ * request_irq does) and the memory allocators may not have been
+ * initialised.
+ *
+ * 1. initialise the port into a state where it can send characters in the
+ *    console write method.
+ *
+ * 2. don't do the actual hardware shutdown in your shutdown() method (but
+ *    do the normal software shutdown - ie, free irqs etc)
+ *****
+ */
+static void ip22zilog_shutdown(struct uart_port *port)
+{
+	struct uart_ip22zilog_port *up = UART_ZILOG(port);
+	struct zilog_channel *channel;
+	unsigned long flags;
+
+	if (ZS_IS_CONS(up))
+		return;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	channel = ZILOG_CHANNEL_FROM_PORT(port);
+
+	/* Disable receiver and transmitter.  */
+	up->curregs[R3] &= ~RxENAB;
+	up->curregs[R5] &= ~TxENAB;
+
+	/* Disable all interrupts and BRK assertion.  */
+	up->curregs[R1] &= ~(EXT_INT_ENAB | TxINT_ENAB | RxINT_MASK);
+	up->curregs[R5] &= ~SND_BRK;
+	ip22zilog_maybe_update_regs(up, channel);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* Shared by TTY driver and serial console setup.  The port lock is held
+ * and local interrupts are disabled.
+ */
+static void
+ip22zilog_convert_to_zs(struct uart_ip22zilog_port *up, unsigned int cflag,
+		       unsigned int iflag, int brg)
+{
+
+	up->curregs[R10] = NRZ;
+	up->curregs[R11] = TCBR | RCBR;
+
+	/* Program BAUD and clock source. */
+	up->curregs[R4] &= ~XCLK_MASK;
+	up->curregs[R4] |= X16CLK;
+	up->curregs[R12] = brg & 0xff;
+	up->curregs[R13] = (brg >> 8) & 0xff;
+	up->curregs[R14] = BRENAB;
+
+	/* Character size, stop bits, and parity. */
+	up->curregs[3] &= ~RxN_MASK;
+	up->curregs[5] &= ~TxN_MASK;
+	switch (cflag & CSIZE) {
+	case CS5:
+		up->curregs[3] |= Rx5;
+		up->curregs[5] |= Tx5;
+		up->parity_mask = 0x1f;
+		break;
+	case CS6:
+		up->curregs[3] |= Rx6;
+		up->curregs[5] |= Tx6;
+		up->parity_mask = 0x3f;
+		break;
+	case CS7:
+		up->curregs[3] |= Rx7;
+		up->curregs[5] |= Tx7;
+		up->parity_mask = 0x7f;
+		break;
+	case CS8:
+	default:
+		up->curregs[3] |= Rx8;
+		up->curregs[5] |= Tx8;
+		up->parity_mask = 0xff;
+		break;
+	};
+	up->curregs[4] &= ~0x0c;
+	if (cflag & CSTOPB)
+		up->curregs[4] |= SB2;
+	else
+		up->curregs[4] |= SB1;
+	if (cflag & PARENB)
+		up->curregs[4] |= PAR_ENAB;
+	else
+		up->curregs[4] &= ~PAR_ENAB;
+	if (!(cflag & PARODD))
+		up->curregs[4] |= PAR_EVEN;
+	else
+		up->curregs[4] &= ~PAR_EVEN;
+
+	up->port.read_status_mask = Rx_OVR;
+	if (iflag & INPCK)
+		up->port.read_status_mask |= CRC_ERR | PAR_ERR;
+	if (iflag & (BRKINT | PARMRK))
+		up->port.read_status_mask |= BRK_ABRT;
+
+	up->port.ignore_status_mask = 0;
+	if (iflag & IGNPAR)
+		up->port.ignore_status_mask |= CRC_ERR | PAR_ERR;
+	if (iflag & IGNBRK) {
+		up->port.ignore_status_mask |= BRK_ABRT;
+		if (iflag & IGNPAR)
+			up->port.ignore_status_mask |= Rx_OVR;
+	}
+
+	if ((cflag & CREAD) == 0)
+		up->port.ignore_status_mask = 0xff;
+}
+
+/* The port lock is not held.  */
+static void
+ip22zilog_set_termios(struct uart_port *port, struct termios *termios,
+		      struct termios *old)
+{
+	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	unsigned long flags;
+	int baud, brg;
+
+	baud = uart_get_baud_rate(port, termios, old, 1200, 76800);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	brg = BPS_TO_BRG(baud, ZS_CLOCK / ZS_CLOCK_DIVISOR);
+
+	ip22zilog_convert_to_zs(up, termios->c_cflag, termios->c_iflag, brg);
+
+	if (UART_ENABLE_MS(&up->port, termios->c_cflag))
+		up->flags |= IP22ZILOG_FLAG_MODEM_STATUS;
+	else
+		up->flags &= ~IP22ZILOG_FLAG_MODEM_STATUS;
+
+	up->cflag = termios->c_cflag;
+
+	ip22zilog_maybe_update_regs(up, ZILOG_CHANNEL_FROM_PORT(port));
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+static const char *ip22zilog_type(struct uart_port *port)
+{
+	return "IP22-Zilog";
+}
+
+/* We do not request/release mappings of the registers here, this
+ * happens at early serial probe time.
+ */
+static void ip22zilog_release_port(struct uart_port *port)
+{
+}
+
+static int ip22zilog_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+/* These do not need to do anything interesting either.  */
+static void ip22zilog_config_port(struct uart_port *port, int flags)
+{
+}
+
+/* We do not support letting the user mess with the divisor, IRQ, etc. */
+static int ip22zilog_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	return -EINVAL;
+}
+
+static struct uart_ops ip22zilog_pops = {
+	.tx_empty	=	ip22zilog_tx_empty,
+	.set_mctrl	=	ip22zilog_set_mctrl,
+	.get_mctrl	=	ip22zilog_get_mctrl,
+	.stop_tx	=	ip22zilog_stop_tx,
+	.start_tx	=	ip22zilog_start_tx,
+	.stop_rx	=	ip22zilog_stop_rx,
+	.enable_ms	=	ip22zilog_enable_ms,
+	.break_ctl	=	ip22zilog_break_ctl,
+	.startup	=	ip22zilog_startup,
+	.shutdown	=	ip22zilog_shutdown,
+	.set_termios	=	ip22zilog_set_termios,
+	.type		=	ip22zilog_type,
+	.release_port	=	ip22zilog_release_port,
+	.request_port	=	ip22zilog_request_port,
+	.config_port	=	ip22zilog_config_port,
+	.verify_port	=	ip22zilog_verify_port,
+};
+
+static struct uart_ip22zilog_port *ip22zilog_port_table;
+static struct zilog_layout **ip22zilog_chip_regs;
+
+static struct uart_ip22zilog_port *ip22zilog_irq_chain;
+static int zilog_irq = -1;
+
+static void * __init alloc_one_table(unsigned long size)
+{
+	void *ret;
+
+	ret = kmalloc(size, GFP_KERNEL);
+	if (ret != NULL)
+		memset(ret, 0, size);
+
+	return ret;
+}
+
+static void __init ip22zilog_alloc_tables(void)
+{
+	ip22zilog_port_table = (struct uart_ip22zilog_port *)
+		alloc_one_table(NUM_CHANNELS * sizeof(struct uart_ip22zilog_port));
+	ip22zilog_chip_regs = (struct zilog_layout **)
+		alloc_one_table(NUM_IP22ZILOG * sizeof(struct zilog_layout *));
+
+	if (ip22zilog_port_table == NULL || ip22zilog_chip_regs == NULL) {
+		panic("IP22-Zilog: Cannot allocate IP22-Zilog tables.");
+	}
+}
+
+/* Get the address of the registers for IP22-Zilog instance CHIP.  */
+static struct zilog_layout * __init get_zs(int chip)
+{
+	unsigned long base;
+
+	if (chip < 0 || chip >= NUM_IP22ZILOG) {
+		panic("IP22-Zilog: Illegal chip number %d in get_zs.", chip);
+	}
+
+	/* Not probe-able, hard code it. */
+	base = (unsigned long) &sgioc->uart;
+
+	zilog_irq = SGI_SERIAL_IRQ;
+	request_mem_region(base, 8, "IP22-Zilog");
+
+	return (struct zilog_layout *) base;
+}
+
+#define ZS_PUT_CHAR_MAX_DELAY	2000	/* 10 ms */
+
+#ifdef CONFIG_SERIAL_IP22_ZILOG_CONSOLE
+static void ip22zilog_put_char(struct zilog_channel *channel, unsigned char ch)
+{
+	int loops = ZS_PUT_CHAR_MAX_DELAY;
+
+	/* This is a timed polling loop so do not switch the explicit
+	 * udelay with ZSDELAY as that is a NOP on some platforms.  -DaveM
+	 */
+	do {
+		unsigned char val = readb(&channel->control);
+		if (val & Tx_BUF_EMP) {
+			ZSDELAY();
+			break;
+		}
+		udelay(5);
+	} while (--loops);
+
+	writeb(ch, &channel->data);
+	ZSDELAY();
+	ZS_WSYNC(channel);
+}
+
+static void
+ip22zilog_console_write(struct console *con, const char *s, unsigned int count)
+{
+	struct uart_ip22zilog_port *up = &ip22zilog_port_table[con->index];
+	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+	unsigned long flags;
+	int i;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	for (i = 0; i < count; i++, s++) {
+		ip22zilog_put_char(channel, *s);
+		if (*s == 10)
+			ip22zilog_put_char(channel, 13);
+	}
+	udelay(2);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+void
+ip22serial_console_termios(struct console *con, char *options)
+{
+	int baud = 9600, bits = 8, cflag;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	cflag = CREAD | HUPCL | CLOCAL;
+
+	switch (baud) {
+		case 150: cflag |= B150; break;
+		case 300: cflag |= B300; break;
+		case 600: cflag |= B600; break;
+		case 1200: cflag |= B1200; break;
+		case 2400: cflag |= B2400; break;
+		case 4800: cflag |= B4800; break;
+		case 9600: cflag |= B9600; break;
+		case 19200: cflag |= B19200; break;
+		case 38400: cflag |= B38400; break;
+		default: baud = 9600; cflag |= B9600; break;
+	}
+
+	con->cflag = cflag | CS8;			/* 8N1 */
+}
+
+static int __init ip22zilog_console_setup(struct console *con, char *options)
+{
+	struct uart_ip22zilog_port *up = &ip22zilog_port_table[con->index];
+	unsigned long flags;
+	int baud, brg;
+
+	printk("Console: ttyS%d (IP22-Zilog)\n", con->index);
+
+	/* Get firmware console settings.  */
+	ip22serial_console_termios(con, options);
+
+	/* Firmware console speed is limited to 150-->38400 baud so
+	 * this hackish cflag thing is OK.
+	 */
+	switch (con->cflag & CBAUD) {
+	case B150: baud = 150; break;
+	case B300: baud = 300; break;
+	case B600: baud = 600; break;
+	case B1200: baud = 1200; break;
+	case B2400: baud = 2400; break;
+	case B4800: baud = 4800; break;
+	default: case B9600: baud = 9600; break;
+	case B19200: baud = 19200; break;
+	case B38400: baud = 38400; break;
+	};
+
+	brg = BPS_TO_BRG(baud, ZS_CLOCK / ZS_CLOCK_DIVISOR);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	up->curregs[R15] = BRKIE;
+	ip22zilog_convert_to_zs(up, con->cflag, 0, brg);
+
+	__ip22zilog_startup(up);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	return 0;
+}
+
+static struct uart_driver ip22zilog_reg;
+
+static struct console ip22zilog_console = {
+	.name	=	"ttyS",
+	.write	=	ip22zilog_console_write,
+	.device	=	uart_console_device,
+	.setup	=	ip22zilog_console_setup,
+	.flags	=	CON_PRINTBUFFER,
+	.index	=	-1,
+	.data	=	&ip22zilog_reg,
+};
+#endif /* CONFIG_SERIAL_IP22_ZILOG_CONSOLE */
+
+static struct uart_driver ip22zilog_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= "serial",
+	.devfs_name	= "tts/",
+	.dev_name	= "ttyS",
+	.major		= TTY_MAJOR,
+	.minor		= 64,
+	.nr		= NUM_CHANNELS,
+#ifdef CONFIG_SERIAL_IP22_ZILOG_CONSOLE
+	.cons		= &ip22zilog_console,
+#endif
+};
+
+static void __init ip22zilog_prepare(void)
+{
+	struct uart_ip22zilog_port *up;
+	struct zilog_layout *rp;
+	int channel, chip;
+
+	/*
+	 * Temporary fix.
+	 */
+	for (channel = 0; channel < NUM_CHANNELS; channel++)
+		spin_lock_init(&ip22zilog_port_table[channel].port.lock);
+
+	ip22zilog_irq_chain = &ip22zilog_port_table[NUM_CHANNELS - 1];
+        up = &ip22zilog_port_table[0];
+	for (channel = NUM_CHANNELS - 1 ; channel > 0; channel--)
+		up[channel].next = &up[channel - 1];
+	up[channel].next = NULL;
+
+	for (chip = 0; chip < NUM_IP22ZILOG; chip++) {
+		if (!ip22zilog_chip_regs[chip]) {
+			ip22zilog_chip_regs[chip] = rp = get_zs(chip);
+
+			up[(chip * 2) + 0].port.membase = (char *) &rp->channelB;
+			up[(chip * 2) + 1].port.membase = (char *) &rp->channelA;
+
+			/* In theory mapbase is the physical address ...  */
+			up[(chip * 2) + 0].port.mapbase =
+				(unsigned long) ioremap((unsigned long) &rp->channelB, 8);
+			up[(chip * 2) + 1].port.mapbase =
+				(unsigned long) ioremap((unsigned long) &rp->channelA, 8);
+		}
+
+		/* Channel A */
+		up[(chip * 2) + 0].port.iotype = UPIO_MEM;
+		up[(chip * 2) + 0].port.irq = zilog_irq;
+		up[(chip * 2) + 0].port.uartclk = ZS_CLOCK;
+		up[(chip * 2) + 0].port.fifosize = 1;
+		up[(chip * 2) + 0].port.ops = &ip22zilog_pops;
+		up[(chip * 2) + 0].port.type = PORT_IP22ZILOG;
+		up[(chip * 2) + 0].port.flags = 0;
+		up[(chip * 2) + 0].port.line = (chip * 2) + 0;
+		up[(chip * 2) + 0].flags = 0;
+
+		/* Channel B */
+		up[(chip * 2) + 1].port.iotype = UPIO_MEM;
+		up[(chip * 2) + 1].port.irq = zilog_irq;
+		up[(chip * 2) + 1].port.uartclk = ZS_CLOCK;
+		up[(chip * 2) + 1].port.fifosize = 1;
+		up[(chip * 2) + 1].port.ops = &ip22zilog_pops;
+		up[(chip * 2) + 1].port.type = PORT_IP22ZILOG;
+		up[(chip * 2) + 1].port.flags |= IP22ZILOG_FLAG_IS_CHANNEL_A;
+		up[(chip * 2) + 1].port.line = (chip * 2) + 1;
+		up[(chip * 2) + 1].flags = 0;
+	}
+}
+
+static void __init ip22zilog_init_hw(void)
+{
+	int i;
+
+	for (i = 0; i < NUM_CHANNELS; i++) {
+		struct uart_ip22zilog_port *up = &ip22zilog_port_table[i];
+		struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+		unsigned long flags;
+		int baud, brg;
+
+		spin_lock_irqsave(&up->port.lock, flags);
+
+		if (ZS_IS_CHANNEL_A(up)) {
+			write_zsreg(channel, R9, FHWRES);
+			ZSDELAY_LONG();
+			(void) read_zsreg(channel, R0);
+		}
+
+		/* Normal serial TTY. */
+		up->parity_mask = 0xff;
+		up->curregs[R1] = EXT_INT_ENAB | INT_ALL_Rx | TxINT_ENAB;
+		up->curregs[R4] = PAR_EVEN | X16CLK | SB1;
+		up->curregs[R3] = RxENAB | Rx8;
+		up->curregs[R5] = TxENAB | Tx8;
+		up->curregs[R9] = NV | MIE;
+		up->curregs[R10] = NRZ;
+		up->curregs[R11] = TCBR | RCBR;
+		baud = 9600;
+		brg = BPS_TO_BRG(baud, ZS_CLOCK / ZS_CLOCK_DIVISOR);
+		up->curregs[R12] = (brg & 0xff);
+		up->curregs[R13] = (brg >> 8) & 0xff;
+		up->curregs[R14] = BRENAB;
+		__load_zsregs(channel, up->curregs);
+	        /* set master interrupt enable */
+	        write_zsreg(channel, R9, up->curregs[R9]);
+
+		spin_unlock_irqrestore(&up->port.lock, flags);
+	}
+}
+
+static int __init ip22zilog_ports_init(void)
+{
+	int ret;
+
+	printk(KERN_INFO "Serial: IP22 Zilog driver (%d chips).\n", NUM_IP22ZILOG);
+
+	ip22zilog_prepare();
+
+	if (request_irq(zilog_irq, ip22zilog_interrupt, 0,
+			"IP22-Zilog", ip22zilog_irq_chain)) {
+		panic("IP22-Zilog: Unable to register zs interrupt handler.\n");
+	}
+
+	ip22zilog_init_hw();
+
+	ret = uart_register_driver(&ip22zilog_reg);
+	if (ret == 0) {
+		int i;
+
+		for (i = 0; i < NUM_CHANNELS; i++) {
+			struct uart_ip22zilog_port *up = &ip22zilog_port_table[i];
+
+			uart_add_one_port(&ip22zilog_reg, &up->port);
+		}
+	}
+
+	return ret;
+}
+
+static int __init ip22zilog_init(void)
+{
+	/* IP22 Zilog setup is hard coded, no probing to do.  */
+	ip22zilog_alloc_tables();
+	ip22zilog_ports_init();
+
+	return 0;
+}
+
+static void __exit ip22zilog_exit(void)
+{
+	int i;
+
+	for (i = 0; i < NUM_CHANNELS; i++) {
+		struct uart_ip22zilog_port *up = &ip22zilog_port_table[i];
+
+		uart_remove_one_port(&ip22zilog_reg, &up->port);
+	}
+
+	uart_unregister_driver(&ip22zilog_reg);
+}
+
+module_init(ip22zilog_init);
+module_exit(ip22zilog_exit);
+
+/* David wrote it but I'm to blame for the bugs ...  */
+MODULE_AUTHOR("Ralf Baechle <ralf@linux-mips.org>");
+MODULE_DESCRIPTION("SGI Zilog serial port driver");
+MODULE_LICENSE("GPL");