[PATCH] sb1250-duart.c: SB1250 DUART serial support

[PATCH] sb1250-duart.c: SB1250 DUART serial support

[Maciej W. Rozycki]

 This is a driver for the SB1250 DUART, a dual serial port implementation 
included in the Broadcom family of SOCs descending from the SiByte SB1250 
MIPS64 chip multiprocessor.  It is a new implementation replacing the 
old-fashioned driver currently present in the linux-mips.org tree.  It 
supports all the usual features one would expect from a(n asynchronous) 
serial driver, including modem line control (as far as hardware supports 
it -- there is edge detection logic missing from the DCD and RI lines and 
the driver does not implement polling of these lines at the moment), the 
serial console, BREAK transmission and reception, including the magic 
SysRq.  The receive FIFO threshold is not maintained though.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
---
Hi,

 The driver was tested with a SWARM board which uses a BCM1250 SOC (which 
is dual MIPS64 CMP) and has both ports of the single DUART implemented 
wired externally.  Both were tested.  Testing included using the ports as 
terminal lines at 1200bps (which is the ports minimum), 115200bps and a 
couple of random speeds inbetween.  The modem lines were verified to 
operate correctly.  No testing was performed with a use as a network 
interface, like with SLIP or PPP.

 The driver builds succesfully and without warnings both as integrated and 
as modular.  There are a couple of -W warnings, but they are results of 
some inconsistencies (signedness mismatches) in the serial core.  It 
produces no sparse warnings.  There are a few benign warnings from 
patchcheck.pl, one of which is, I believe, a bug in the script itself 
(maintainers cc-ed):

printk() should include KERN_ facility level
#750: FILE: drivers/serial/sb1250-duart.c:675:
+		printk(err);

The <asm/io.h> warning is, I gather, not a problem and warnings about the 
_SB_MAKEMASK() macro should be addressed as a separate change.

 The driver runs correctly with a 64-bit SMP kernel in a big- and 
little-endian configuration (with spinlock debugging enabled).  Modular 
configuration was not tested at the run time.  UP configuration was not 
tested at all, but is not expected to give any troubles.

 I have asked for testing at the linux-mips list, but rather than results 
I have received some pressure to push the patch regardless.  So here it 
goes. ;-)

 Please apply.

  Maciej

patch-2.6.22-20070712-serial-sb1250-duart-28
diff -up --recursive --new-file linux-2.6.22-20070712.macro/arch/mips/sibyte/bcm1480/setup.c linux-2.6.22-20070712/arch/mips/sibyte/bcm1480/setup.c
--- linux-2.6.22-20070712.macro/arch/mips/sibyte/bcm1480/setup.c	2007-07-12 02:55:17.000000000 +0000
+++ linux-2.6.22-20070712/arch/mips/sibyte/bcm1480/setup.c	2007-07-12 14:26:21.000000000 +0000
@@ -31,6 +31,7 @@
 unsigned int sb1_pass;
 unsigned int soc_pass;
 unsigned int soc_type;
+EXPORT_SYMBOL(soc_type);
 unsigned int periph_rev;
 unsigned int zbbus_mhz;
 
diff -up --recursive --new-file linux-2.6.22-20070712.macro/arch/mips/sibyte/sb1250/setup.c linux-2.6.22-20070712/arch/mips/sibyte/sb1250/setup.c
--- linux-2.6.22-20070712.macro/arch/mips/sibyte/sb1250/setup.c	2007-07-12 02:55:17.000000000 +0000
+++ linux-2.6.22-20070712/arch/mips/sibyte/sb1250/setup.c	2007-07-12 14:26:21.000000000 +0000
@@ -31,6 +31,7 @@
 unsigned int sb1_pass;
 unsigned int soc_pass;
 unsigned int soc_type;
+EXPORT_SYMBOL(soc_type);
 unsigned int periph_rev;
 unsigned int zbbus_mhz;
 EXPORT_SYMBOL(zbbus_mhz);
diff -up --recursive --new-file linux-2.6.22-20070712.macro/drivers/serial/Kconfig linux-2.6.22-20070712/drivers/serial/Kconfig
--- linux-2.6.22-20070712.macro/drivers/serial/Kconfig	2007-07-12 02:55:29.000000000 +0000
+++ linux-2.6.22-20070712/drivers/serial/Kconfig	2007-07-12 17:34:55.000000000 +0000
@@ -324,6 +324,34 @@ config SERIAL_AMBA_PL011_CONSOLE
 	  your boot loader (lilo or loadlin) about how to pass options to the
 	  kernel at boot time.)
 
+config SERIAL_SB1250_DUART
+	tristate "BCM1xxx on-chip DUART serial support"
+	depends on SIBYTE_SB1xxx_SOC=y
+	select SERIAL_CORE
+	default y
+	---help---
+	  Support for the asynchronous serial interface (DUART) included in
+	  the BCM1250 and derived System-On-a-Chip (SOC) devices.  Note that
+	  the letter D in DUART stands for "dual", which is how the device
+	  is implemented.  Depending on the SOC configuration there may be
+	  one or more DUARTs available of which all are handled.
+
+	  If unsure, say Y.  To compile this driver as a module, choose M here:
+	  the module will be called sb1250-duart.
+
+config SERIAL_SB1250_DUART_CONSOLE
+	bool "Support for console on a BCM1xxx DUART serial port"
+	depends on SERIAL_SB1250_DUART=y
+	select SERIAL_CORE_CONSOLE
+	default y
+	---help---
+	  If you say Y here, it will be possible to use a serial port as the
+	  system console (the system console is the device which receives all
+	  kernel messages and warnings and which allows logins in single user
+	  mode).
+
+	  If unsure, say Y.
+
 config SERIAL_ATMEL
 	bool "AT91 / AT32 on-chip serial port support"
 	depends on (ARM && ARCH_AT91) || AVR32
diff -up --recursive --new-file linux-2.6.22-20070712.macro/drivers/serial/Makefile linux-2.6.22-20070712/drivers/serial/Makefile
--- linux-2.6.22-20070712.macro/drivers/serial/Makefile	2007-07-12 02:55:29.000000000 +0000
+++ linux-2.6.22-20070712/drivers/serial/Makefile	2007-07-12 14:26:21.000000000 +0000
@@ -23,6 +23,7 @@ obj-$(CONFIG_SERIAL_8250_MCA) += 8250_mc
 obj-$(CONFIG_SERIAL_8250_AU1X00) += 8250_au1x00.o
 obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
 obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
+obj-$(CONFIG_SERIAL_SB1250_DUART) += sb1250-duart.o
 obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
 obj-$(CONFIG_SERIAL_PXA) += pxa.o
 obj-$(CONFIG_SERIAL_PNX8XXX) += pnx8xxx_uart.o
diff -up --recursive --new-file linux-2.6.22-20070712.macro/drivers/serial/sb1250-duart.c linux-2.6.22-20070712/drivers/serial/sb1250-duart.c
--- linux-2.6.22-20070712.macro/drivers/serial/sb1250-duart.c	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.22-20070712/drivers/serial/sb1250-duart.c	2007-07-11 02:17:35.000000000 +0000
@@ -0,0 +1,972 @@
+/*
+ *	drivers/serial/sb1250-duart.c
+ *
+ *	Support for the asynchronous serial interface (DUART) included
+ *	in the BCM1250 and derived System-On-a-Chip (SOC) devices.
+ *
+ *	Copyright (c) 2007  Maciej W. Rozycki
+ *
+ *	Derived from drivers/char/sb1250_duart.c for which the following
+ *	copyright applies:
+ *
+ *	Copyright (c) 2000, 2001, 2002, 2003, 2004  Broadcom Corporation
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *	References:
+ *
+ *	"BCM1250/BCM1125/BCM1125H User Manual", Broadcom Corporation
+ */
+
+#if defined(CONFIG_SERIAL_SB1250_DUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/kernel.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/types.h>
+
+#include <asm/atomic.h>
+#include <asm/io.h>
+#include <asm/war.h>
+
+#include <asm/sibyte/sb1250.h>
+#include <asm/sibyte/sb1250_uart.h>
+#include <asm/sibyte/swarm.h>
+
+
+#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
+#include <asm/sibyte/bcm1480_regs.h>
+#include <asm/sibyte/bcm1480_int.h>
+
+#define SBD_CHANREGS(line)	A_BCM1480_DUART_CHANREG((line), 0)
+#define SBD_CTRLREGS(line)	A_BCM1480_DUART_CTRLREG((line), 0)
+#define SBD_INT(line)		(K_BCM1480_INT_UART_0 + (line))
+
+#elif defined(CONFIG_SIBYTE_SB1250) || defined(CONFIG_SIBYTE_BCM112X)
+#include <asm/sibyte/sb1250_regs.h>
+#include <asm/sibyte/sb1250_int.h>
+
+#define SBD_CHANREGS(line)	A_DUART_CHANREG((line), 0)
+#define SBD_CTRLREGS(line)	A_DUART_CTRLREG(0)
+#define SBD_INT(line)		(K_INT_UART_0 + (line))
+
+#else
+#error invalid SB1250 UART configuration
+
+#endif
+
+
+MODULE_AUTHOR("Maciej W. Rozycki <macro@linux-mips.org>");
+MODULE_DESCRIPTION("BCM1xxx on-chip DUART serial driver");
+MODULE_LICENSE("GPL");
+
+
+#define DUART_MAX_CHIP 2
+#define DUART_MAX_SIDE 2
+
+/*
+ * Per-port state.
+ */
+struct sbd_port {
+	struct sbd_duart	*duart;
+	struct uart_port	port;
+	unsigned char __iomem	*memctrl;
+	int			tx_stopped;
+	int			initialised;
+};
+
+/*
+ * Per-DUART state for the shared register space.
+ */
+struct sbd_duart {
+	struct sbd_port		sport[2];
+	unsigned long		mapctrl;
+	atomic_t		map_guard;
+};
+
+#define to_sport(uport) container_of(uport, struct sbd_port, port)
+
+static struct sbd_duart sbd_duarts[DUART_MAX_CHIP];
+
+#define __unused __attribute__((__unused__))
+
+
+/*
+ * Reading and writing SB1250 DUART registers.
+ *
+ * There are three register spaces: two per-channel ones and
+ * a shared one.  We have to define accessors appropriately.
+ * All registers are 64-bit and all but the Baud Rate Clock
+ * registers only define 8 least significant bits.  There is
+ * also a workaround to take into account.  Raw accessors use
+ * the full register width, but cooked ones truncate it
+ * intentionally so that the rest of the driver does not care.
+ */
+static u64 __read_sbdchn(struct sbd_port *sport, int reg)
+{
+	void __iomem *csr = sport->port.membase + reg;
+
+	return __raw_readq(csr);
+}
+
+static u64 __read_sbdshr(struct sbd_port *sport, int reg)
+{
+	void __iomem *csr = sport->memctrl + reg;
+
+	return __raw_readq(csr);
+}
+
+static void __write_sbdchn(struct sbd_port *sport, int reg, u64 value)
+{
+	void __iomem *csr = sport->port.membase + reg;
+
+	__raw_writeq(value, csr);
+}
+
+static void __write_sbdshr(struct sbd_port *sport, int reg, u64 value)
+{
+	void __iomem *csr = sport->memctrl + reg;
+
+	__raw_writeq(value, csr);
+}
+
+/*
+ * In bug 1956, we get glitches that can mess up uart registers.  This
+ * "read-mode-reg after any register access" is an accepted workaround.
+ */
+static void __war_sbd1956(struct sbd_port *sport)
+{
+	__read_sbdchn(sport, R_DUART_MODE_REG_1);
+	__read_sbdchn(sport, R_DUART_MODE_REG_2);
+}
+
+static unsigned char read_sbdchn(struct sbd_port *sport, int reg)
+{
+	unsigned char retval;
+
+	retval = __read_sbdchn(sport, reg);
+	if (SIBYTE_1956_WAR)
+		__war_sbd1956(sport);
+	return retval;
+}
+
+static unsigned char read_sbdshr(struct sbd_port *sport, int reg)
+{
+	unsigned char retval;
+
+	retval = __read_sbdshr(sport, reg);
+	if (SIBYTE_1956_WAR)
+		__war_sbd1956(sport);
+	return retval;
+}
+
+static void write_sbdchn(struct sbd_port *sport, int reg, unsigned int value)
+{
+	__write_sbdchn(sport, reg, value);
+	if (SIBYTE_1956_WAR)
+		__war_sbd1956(sport);
+}
+
+static void write_sbdshr(struct sbd_port *sport, int reg, unsigned int value)
+{
+	__write_sbdshr(sport, reg, value);
+	if (SIBYTE_1956_WAR)
+		__war_sbd1956(sport);
+}
+
+
+static int sbd_receive_ready(struct sbd_port *sport)
+{
+	return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_RX_RDY;
+}
+
+static int sbd_receive_drain(struct sbd_port *sport)
+{
+	int loops = 10000;
+
+	while (sbd_receive_ready(sport) && loops--)
+		read_sbdchn(sport, R_DUART_RX_HOLD);
+	return loops;
+}
+
+static int __unused sbd_transmit_ready(struct sbd_port *sport)
+{
+	return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_TX_RDY;
+}
+
+static int __unused sbd_transmit_drain(struct sbd_port *sport)
+{
+	int loops = 10000;
+
+	while (!sbd_transmit_ready(sport) && loops--)
+		udelay(2);
+	return loops;
+}
+
+static int sbd_transmit_empty(struct sbd_port *sport)
+{
+	return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_TX_EMT;
+}
+
+static int sbd_line_drain(struct sbd_port *sport)
+{
+	int loops = 10000;
+
+	while (!sbd_transmit_empty(sport) && loops--)
+		udelay(2);
+	return loops;
+}
+
+
+static unsigned int sbd_tx_empty(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	return sbd_transmit_empty(sport) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int sbd_get_mctrl(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+	unsigned int mctrl, status;
+
+	status = read_sbdshr(sport, R_DUART_IN_PORT);
+	status >>= (uport->line) % 2;
+	mctrl = (!(status & M_DUART_IN_PIN0_VAL) ? TIOCM_CTS : 0) |
+		(!(status & M_DUART_IN_PIN4_VAL) ? TIOCM_CAR : 0) |
+		(!(status & M_DUART_RIN0_PIN) ? TIOCM_RNG : 0) |
+		(!(status & M_DUART_IN_PIN2_VAL) ? TIOCM_DSR : 0);
+	return mctrl;
+}
+
+static void sbd_set_mctrl(struct uart_port *uport, unsigned int mctrl)
+{
+	struct sbd_port *sport = to_sport(uport);
+	unsigned int clr = 0, set = 0, mode2;
+
+	if (mctrl & TIOCM_DTR)
+		set |= M_DUART_SET_OPR2;
+	else
+		clr |= M_DUART_CLR_OPR2;
+	if (mctrl & TIOCM_RTS)
+		set |= M_DUART_SET_OPR0;
+	else
+		clr |= M_DUART_CLR_OPR0;
+	clr <<= (uport->line) % 2;
+	set <<= (uport->line) % 2;
+
+	mode2 = read_sbdchn(sport, R_DUART_MODE_REG_2);
+	mode2 &= ~M_DUART_CHAN_MODE;
+	if (mctrl & TIOCM_LOOP)
+		mode2 |= V_DUART_CHAN_MODE_LCL_LOOP;
+	else
+		mode2 |= V_DUART_CHAN_MODE_NORMAL;
+
+	write_sbdshr(sport, R_DUART_CLEAR_OPR, clr);
+	write_sbdshr(sport, R_DUART_SET_OPR, set);
+	write_sbdchn(sport, R_DUART_MODE_REG_2, mode2);
+}
+
+static void sbd_stop_tx(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS);
+	sport->tx_stopped = 1;
+};
+
+static void sbd_start_tx(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+	unsigned int mask;
+
+	/* Enable tx interrupts.  */
+	mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
+	mask |= M_DUART_IMR_TX;
+	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask);
+
+	/* Go!, go!, go!...  */
+	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_EN);
+	sport->tx_stopped = 0;
+};
+
+static void sbd_stop_rx(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), 0);
+};
+
+static void sbd_enable_ms(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	write_sbdchn(sport, R_DUART_AUXCTL_X,
+		     M_DUART_CIN_CHNG_ENA | M_DUART_CTS_CHNG_ENA);
+}
+
+static void sbd_break_ctl(struct uart_port *uport, int break_state)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	if (break_state == -1)
+		write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_START_BREAK);
+	else
+		write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_STOP_BREAK);
+}
+
+
+static void sbd_receive_chars(struct sbd_port *sport)
+{
+	struct uart_port *uport = &sport->port;
+	struct uart_icount *icount;
+	unsigned int status, ch, flag;
+	int count;
+
+	for (count = 16; count; count--) {
+		status = read_sbdchn(sport, R_DUART_STATUS);
+		if (!(status & M_DUART_RX_RDY))
+			break;
+
+		ch = read_sbdchn(sport, R_DUART_RX_HOLD);
+
+		flag = TTY_NORMAL;
+
+		icount = &uport->icount;
+		icount->rx++;
+
+		if (unlikely(status &
+			     (M_DUART_RCVD_BRK | M_DUART_FRM_ERR |
+			      M_DUART_PARITY_ERR | M_DUART_OVRUN_ERR))) {
+			if (status & M_DUART_RCVD_BRK) {
+				icount->brk++;
+				if (uart_handle_break(uport))
+					continue;
+			} else if (status & M_DUART_FRM_ERR)
+				icount->frame++;
+			else if (status & M_DUART_PARITY_ERR)
+				icount->parity++;
+			if (status & M_DUART_OVRUN_ERR)
+				icount->overrun++;
+
+			status &= uport->read_status_mask;
+			if (status & M_DUART_RCVD_BRK)
+				flag = TTY_BREAK;
+			else if (status & M_DUART_FRM_ERR)
+				flag = TTY_FRAME;
+			else if (status & M_DUART_PARITY_ERR)
+				flag = TTY_PARITY;
+		}
+
+		if (uart_handle_sysrq_char(uport, ch))
+			continue;
+
+		uart_insert_char(uport, status, M_DUART_OVRUN_ERR, ch, flag);
+	}
+
+	tty_flip_buffer_push(uport->info->tty);
+}
+
+static void sbd_transmit_chars(struct sbd_port *sport)
+{
+	struct uart_port *uport = &sport->port;
+	struct circ_buf *xmit = &sport->port.info->xmit;
+	unsigned int mask;
+	int stop_tx;
+
+	/* XON/XOFF chars.  */
+	if (sport->port.x_char) {
+		write_sbdchn(sport, R_DUART_TX_HOLD, sport->port.x_char);
+		sport->port.icount.tx++;
+		sport->port.x_char = 0;
+		return;
+	}
+
+	/* If nothing to do or stopped or hardware stopped.  */
+	stop_tx = (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port));
+
+	/* Send char.  */
+	if (!stop_tx) {
+		write_sbdchn(sport, R_DUART_TX_HOLD, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		sport->port.icount.tx++;
+
+		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+			uart_write_wakeup(&sport->port);
+	}
+
+	/* Are we are done?  */
+	if (stop_tx || uart_circ_empty(xmit)) {
+		/* Disable tx interrupts.  */
+		mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
+		mask &= ~M_DUART_IMR_TX;
+		write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask);
+	}
+}
+
+static void sbd_status_handle(struct sbd_port *sport)
+{
+	struct uart_port *uport = &sport->port;
+	unsigned int delta;
+
+	delta = read_sbdshr(sport, R_DUART_INCHREG((uport->line) % 2));
+	delta >>= (uport->line) % 2;
+
+	if (delta & (M_DUART_IN_PIN0_VAL << S_DUART_IN_PIN_CHNG))
+		uart_handle_cts_change(uport, !(delta & M_DUART_IN_PIN0_VAL));
+
+	if (delta & (M_DUART_IN_PIN2_VAL << S_DUART_IN_PIN_CHNG))
+		uport->icount.dsr++;
+
+	if (delta & ((M_DUART_IN_PIN2_VAL | M_DUART_IN_PIN0_VAL) <<
+		     S_DUART_IN_PIN_CHNG))
+		wake_up_interruptible(&uport->info->delta_msr_wait);
+}
+
+static irqreturn_t sbd_interrupt(int irq, void *dev_id)
+{
+	struct sbd_port *sport = dev_id;
+	struct uart_port *uport = &sport->port;
+	irqreturn_t status = IRQ_NONE;
+	unsigned int intstat;
+	int count;
+
+	for (count = 16; count; count--) {
+		intstat = read_sbdshr(sport,
+				      R_DUART_ISRREG((uport->line) % 2));
+		intstat &= read_sbdshr(sport,
+				       R_DUART_IMRREG((uport->line) % 2));
+		intstat &= M_DUART_ISR_ALL;
+		if (!intstat)
+			break;
+
+		if (intstat & M_DUART_ISR_RX)
+			sbd_receive_chars(sport);
+		if (intstat & M_DUART_ISR_IN)
+			sbd_status_handle(sport);
+		if (intstat & M_DUART_ISR_TX)
+			sbd_transmit_chars(sport);
+
+		status = IRQ_HANDLED;
+	}
+
+	return status;
+}
+
+
+static int sbd_startup(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+	unsigned int mode1;
+	int ret;
+
+	ret = request_irq(sport->port.irq, sbd_interrupt,
+			  IRQF_SHARED, "sb1250-duart", sport);
+	if (ret)
+		return ret;
+
+	/* Clear the receive FIFO.  */
+	sbd_receive_drain(sport);
+
+	/* Clear the interrupt registers.  */
+	write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_RESET_BREAK_INT);
+	read_sbdshr(sport, R_DUART_INCHREG((uport->line) % 2));
+
+	/* Set rx/tx interrupt to FIFO available.  */
+	mode1 = read_sbdchn(sport, R_DUART_MODE_REG_1);
+	mode1 &= ~(M_DUART_RX_IRQ_SEL_RXFULL | M_DUART_TX_IRQ_SEL_TXEMPT);
+	write_sbdchn(sport, R_DUART_MODE_REG_1, mode1);
+
+	/* Disable tx, enable rx.  */
+	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS | M_DUART_RX_EN);
+	sport->tx_stopped = 1;
+
+	/* Enable interrupts.  */
+	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2),
+		     M_DUART_IMR_IN | M_DUART_IMR_RX);
+
+	return 0;
+}
+
+static void sbd_shutdown(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS | M_DUART_RX_DIS);
+	sport->tx_stopped = 1;
+	free_irq(sport->port.irq, sport);
+}
+
+
+static void sbd_init_port(struct sbd_port *sport)
+{
+	struct uart_port *uport = &sport->port;
+
+	if (sport->initialised)
+		return;
+
+	/* There is no DUART reset feature, so just set some sane defaults.  */
+	write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_RESET_TX);
+	write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_RESET_RX);
+	write_sbdchn(sport, R_DUART_MODE_REG_1, V_DUART_BITS_PER_CHAR_8);
+	write_sbdchn(sport, R_DUART_MODE_REG_2, 0);
+	write_sbdchn(sport, R_DUART_FULL_CTL,
+		     V_DUART_INT_TIME(0) | V_DUART_SIG_FULL(15));
+	write_sbdchn(sport, R_DUART_OPCR_X, 0);
+	write_sbdchn(sport, R_DUART_AUXCTL_X, 0);
+	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), 0);
+
+	sport->initialised = 1;
+}
+
+static void sbd_set_termios(struct uart_port *uport, struct ktermios *termios,
+			    struct ktermios *old_termios)
+{
+	struct sbd_port *sport = to_sport(uport);
+	unsigned int mode1 = 0, mode2 = 0, aux = 0;
+	unsigned int mode1mask = 0, mode2mask = 0, auxmask = 0;
+	unsigned int oldmode1, oldmode2, oldaux;
+	unsigned int baud, brg;
+	unsigned int command;
+
+	mode1mask |= ~(M_DUART_PARITY_MODE | M_DUART_PARITY_TYPE_ODD |
+		       M_DUART_BITS_PER_CHAR);
+	mode2mask |= ~M_DUART_STOP_BIT_LEN_2;
+	auxmask |= ~M_DUART_CTS_CHNG_ENA;
+
+	/* Byte size.  */
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+	case CS6:
+		/* Unsupported, leave unchanged.  */
+		mode1mask |= M_DUART_PARITY_MODE;
+		break;
+	case CS7:
+		mode1 |= V_DUART_BITS_PER_CHAR_7;
+		break;
+	case CS8:
+	default:
+		mode1 |= V_DUART_BITS_PER_CHAR_8;
+		break;
+	}
+
+	/* Parity and stop bits.  */
+	if (termios->c_cflag & CSTOPB)
+		mode2 |= M_DUART_STOP_BIT_LEN_2;
+	else
+		mode2 |= M_DUART_STOP_BIT_LEN_1;
+	if (termios->c_cflag & PARENB)
+		mode1 |= V_DUART_PARITY_MODE_ADD;
+	else
+		mode1 |= V_DUART_PARITY_MODE_NONE;
+	if (termios->c_cflag & PARODD)
+		mode1 |= M_DUART_PARITY_TYPE_ODD;
+	else
+		mode1 |= M_DUART_PARITY_TYPE_EVEN;
+
+	baud = uart_get_baud_rate(uport, termios, old_termios, 1200, 5000000);
+	brg = V_DUART_BAUD_RATE(baud);
+	/* The actual lower bound is 1221bps, so compensate.  */
+	if (brg > M_DUART_CLK_COUNTER)
+		brg = M_DUART_CLK_COUNTER;
+
+	uart_update_timeout(uport, termios->c_cflag, baud);
+
+	uport->read_status_mask = M_DUART_OVRUN_ERR;
+	if (termios->c_iflag & INPCK)
+		uport->read_status_mask |= M_DUART_FRM_ERR |
+					   M_DUART_PARITY_ERR;
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		uport->read_status_mask |= M_DUART_RCVD_BRK;
+
+	uport->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		uport->ignore_status_mask |= M_DUART_FRM_ERR |
+					     M_DUART_PARITY_ERR;
+	if (termios->c_iflag & IGNBRK) {
+		uport->ignore_status_mask |= M_DUART_RCVD_BRK;
+		if (termios->c_iflag & IGNPAR)
+			uport->ignore_status_mask |= M_DUART_OVRUN_ERR;
+	}
+
+	if (termios->c_cflag & CREAD)
+		command = M_DUART_RX_EN;
+	else
+		command = M_DUART_RX_DIS;
+
+	if (termios->c_cflag & CRTSCTS)
+		aux |= M_DUART_CTS_CHNG_ENA;
+	else
+		aux &= ~M_DUART_CTS_CHNG_ENA;
+
+	spin_lock(&uport->lock);
+
+	if (sport->tx_stopped)
+		command |= M_DUART_TX_DIS;
+	else
+		command |= M_DUART_TX_EN;
+
+	oldmode1 = read_sbdchn(sport, R_DUART_MODE_REG_1) & mode1mask;
+	oldmode2 = read_sbdchn(sport, R_DUART_MODE_REG_2) & mode2mask;
+	oldaux = read_sbdchn(sport, R_DUART_AUXCTL_X) & auxmask;
+
+	if (!sport->tx_stopped)
+		sbd_line_drain(sport);
+	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS | M_DUART_RX_DIS);
+
+	write_sbdchn(sport, R_DUART_MODE_REG_1, mode1 | oldmode1);
+	write_sbdchn(sport, R_DUART_MODE_REG_2, mode2 | oldmode2);
+	write_sbdchn(sport, R_DUART_CLK_SEL, brg);
+	write_sbdchn(sport, R_DUART_AUXCTL_X, aux | oldaux);
+
+	write_sbdchn(sport, R_DUART_CMD, command);
+
+	spin_unlock(&uport->lock);
+}
+
+
+static const char *sbd_type(struct uart_port *uport)
+{
+	return "SB1250 DUART";
+}
+
+static void sbd_release_port(struct uart_port *uport)
+{
+	struct sbd_port *sport = to_sport(uport);
+	struct sbd_duart *duart = sport->duart;
+	int map_guard;
+
+	iounmap(sport->memctrl);
+	sport->memctrl = NULL;
+	iounmap(uport->membase);
+	uport->membase = NULL;
+
+	map_guard = atomic_add_return(-1, &duart->map_guard);
+	if (!map_guard)
+		release_mem_region(duart->mapctrl, DUART_CHANREG_SPACING);
+	release_mem_region(uport->mapbase, DUART_CHANREG_SPACING);
+}
+
+static int sbd_map_port(struct uart_port *uport)
+{
+	static const char *err = KERN_ERR "sbd: Cannot map MMIO\n";
+	struct sbd_port *sport = to_sport(uport);
+	struct sbd_duart *duart = sport->duart;
+
+	if (!uport->membase)
+		uport->membase = ioremap_nocache(uport->mapbase,
+						 DUART_CHANREG_SPACING);
+	if (!uport->membase) {
+		printk(err);
+		return -ENOMEM;
+	}
+
+	if (!sport->memctrl)
+		sport->memctrl = ioremap_nocache(duart->mapctrl,
+						 DUART_CHANREG_SPACING);
+	if (!sport->memctrl) {
+		printk(err);
+		iounmap(uport->membase);
+		uport->membase = NULL;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int sbd_request_port(struct uart_port *uport)
+{
+	static const char *err = KERN_ERR
+				 "sbd: Unable to reserve MMIO resource\n";
+	struct sbd_duart *duart = to_sport(uport)->duart;
+	int map_guard;
+	int ret = 0;
+
+	if (!request_mem_region(uport->mapbase, DUART_CHANREG_SPACING,
+				"sb1250-duart")) {
+		printk(err);
+		return -EBUSY;
+	}
+	map_guard = atomic_add_return(1, &duart->map_guard);
+	if (map_guard == 1) {
+		if (!request_mem_region(duart->mapctrl, DUART_CHANREG_SPACING,
+					"sb1250-duart")) {
+			atomic_add(-1, &duart->map_guard);
+			printk(err);
+			ret = -EBUSY;
+		}
+	}
+	if (!ret) {
+		ret = sbd_map_port(uport);
+		if (ret) {
+			map_guard = atomic_add_return(-1, &duart->map_guard);
+			if (!map_guard)
+				release_mem_region(duart->mapctrl,
+						   DUART_CHANREG_SPACING);
+		}
+	}
+	if (ret) {
+		release_mem_region(uport->mapbase, DUART_CHANREG_SPACING);
+		return ret;
+	}
+	return 0;
+}
+
+static void sbd_config_port(struct uart_port *uport, int flags)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	if (flags & UART_CONFIG_TYPE) {
+		if (sbd_request_port(uport))
+			return;
+
+		uport->type = PORT_SB1250_DUART;
+
+		sbd_init_port(sport);
+	}
+}
+
+static int sbd_verify_port(struct uart_port *uport, struct serial_struct *ser)
+{
+	int ret = 0;
+
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_SB1250_DUART)
+		ret = -EINVAL;
+	if (ser->irq != uport->irq)
+		ret = -EINVAL;
+	if (ser->baud_base != uport->uartclk / 16)
+		ret = -EINVAL;
+	return ret;
+}
+
+
+static struct uart_ops sbd_ops = {
+	.tx_empty	= sbd_tx_empty,
+	.set_mctrl	= sbd_set_mctrl,
+	.get_mctrl	= sbd_get_mctrl,
+	.stop_tx	= sbd_stop_tx,
+	.start_tx	= sbd_start_tx,
+	.stop_rx	= sbd_stop_rx,
+	.enable_ms	= sbd_enable_ms,
+	.break_ctl	= sbd_break_ctl,
+	.startup	= sbd_startup,
+	.shutdown	= sbd_shutdown,
+	.set_termios	= sbd_set_termios,
+	.type		= sbd_type,
+	.release_port	= sbd_release_port,
+	.request_port	= sbd_request_port,
+	.config_port	= sbd_config_port,
+	.verify_port	= sbd_verify_port,
+};
+
+/* Initialize SB1250 DUART port structures.  */
+static void __init sbd_probe_duarts(void)
+{
+	static int probed;
+	int chip, side;
+	int max_lines, line;
+
+	if (probed)
+		return;
+
+	/* Set the number of available units based on the SOC type.  */
+	switch (soc_type) {
+	case K_SYS_SOC_TYPE_BCM1x55:
+	case K_SYS_SOC_TYPE_BCM1x80:
+		max_lines = 4;
+		break;
+	default:
+		/* Assume at least two serial ports at the normal address.  */
+		max_lines = 2;
+		break;
+	}
+
+	probed = 1;
+
+	for (chip = 0, line = 0; chip < DUART_MAX_CHIP && line < max_lines;
+	     chip++) {
+		sbd_duarts[chip].mapctrl = SBD_CTRLREGS(line);
+
+		for (side = 0; side < DUART_MAX_SIDE && line < max_lines;
+		     side++, line++) {
+			struct sbd_port *sport = &sbd_duarts[chip].sport[side];
+			struct uart_port *uport = &sport->port;
+
+			sport->duart	= &sbd_duarts[chip];
+
+			uport->irq	= SBD_INT(line);
+			uport->uartclk	= 100000000 / 20 * 16;
+			uport->fifosize	= 16;
+			uport->iotype	= UPIO_MEM;
+			uport->flags	= UPF_BOOT_AUTOCONF;
+			uport->ops	= &sbd_ops;
+			uport->line	= line;
+			uport->mapbase	= SBD_CHANREGS(line);
+		}
+	}
+}
+
+
+#ifdef CONFIG_SERIAL_SB1250_DUART_CONSOLE
+/*
+ * Serial console stuff.  Very basic, polling driver for doing serial
+ * console output.  The console_sem is held by the caller, so we
+ * shouldn't be interrupted for more console activity.
+ */
+static void sbd_console_putchar(struct uart_port *uport, int ch)
+{
+	struct sbd_port *sport = to_sport(uport);
+
+	sbd_transmit_drain(sport);
+	write_sbdchn(sport, R_DUART_TX_HOLD, ch);
+}
+
+static void sbd_console_write(struct console *co, const char *s,
+			      unsigned int count)
+{
+	int chip = co->index / DUART_MAX_SIDE;
+	int side = co->index % DUART_MAX_SIDE;
+	struct sbd_port *sport = &sbd_duarts[chip].sport[side];
+	struct uart_port *uport = &sport->port;
+	unsigned long flags;
+	unsigned int mask;
+
+	/* Disable transmit interrupts and enable the transmitter. */
+	spin_lock_irqsave(&uport->lock, flags);
+	mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
+	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2),
+		     mask & ~M_DUART_IMR_TX);
+	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_EN);
+	spin_unlock_irqrestore(&uport->lock, flags);
+
+	uart_console_write(&sport->port, s, count, sbd_console_putchar);
+
+	/* Restore transmit interrupts and the transmitter enable. */
+	spin_lock_irqsave(&uport->lock, flags);
+	sbd_line_drain(sport);
+	if (sport->tx_stopped)
+		write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS);
+	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask);
+	spin_unlock_irqrestore(&uport->lock, flags);
+}
+
+static int __init sbd_console_setup(struct console *co, char *options)
+{
+	int chip = co->index / DUART_MAX_SIDE;
+	int side = co->index % DUART_MAX_SIDE;
+	struct sbd_port *sport = &sbd_duarts[chip].sport[side];
+	struct uart_port *uport = &sport->port;
+	int baud = 115200;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+	int ret;
+
+	if (!sport->duart)
+		return -ENXIO;
+
+	ret = sbd_map_port(uport);
+	if (ret)
+		return ret;
+
+	sbd_init_port(sport);
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+	return uart_set_options(uport, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver sbd_reg;
+static struct console sbd_console = {
+	.name	= "duart",
+	.write	= sbd_console_write,
+	.device	= uart_console_device,
+	.setup	= sbd_console_setup,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1,
+	.data	= &sbd_reg
+};
+
+static int __init sbd_serial_console_init(void)
+{
+	sbd_probe_duarts();
+	register_console(&sbd_console);
+
+	return 0;
+}
+
+console_initcall(sbd_serial_console_init);
+
+#define SERIAL_SB1250_DUART_CONSOLE	&sbd_console
+#else
+#define SERIAL_SB1250_DUART_CONSOLE	NULL
+#endif /* CONFIG_SERIAL_SB1250_DUART_CONSOLE */
+
+
+static struct uart_driver sbd_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= "serial",
+	.dev_name	= "duart",
+	.major		= TTY_MAJOR,
+	.minor		= SB1250_DUART_MINOR_BASE,
+	.nr		= DUART_MAX_CHIP * DUART_MAX_SIDE,
+	.cons		= SERIAL_SB1250_DUART_CONSOLE,
+};
+
+/* Set up the driver and register it.  */
+static int __init sbd_init(void)
+{
+	int i, ret;
+
+	sbd_probe_duarts();
+
+	ret = uart_register_driver(&sbd_reg);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < DUART_MAX_CHIP * DUART_MAX_SIDE; i++) {
+		struct sbd_duart *duart = &sbd_duarts[i / DUART_MAX_SIDE];
+		struct sbd_port *sport = &duart->sport[i % DUART_MAX_SIDE];
+		struct uart_port *uport = &sport->port;
+
+		if (sport->duart)
+			uart_add_one_port(&sbd_reg, uport);
+	}
+
+	return 0;
+}
+
+/* Unload the driver.  Unregister stuff, get ready to go away.  */
+static void __exit sbd_exit(void)
+{
+	int i;
+
+	for (i = DUART_MAX_CHIP * DUART_MAX_SIDE - 1; i >= 0; i--) {
+		struct sbd_duart *duart = &sbd_duarts[i / DUART_MAX_SIDE];
+		struct sbd_port *sport = &duart->sport[i % DUART_MAX_SIDE];
+		struct uart_port *uport = &sport->port;
+
+		if (sport->duart)
+			uart_remove_one_port(&sbd_reg, uport);
+	}
+
+	uart_unregister_driver(&sbd_reg);
+}
+
+module_init(sbd_init);
+module_exit(sbd_exit);
diff -up --recursive --new-file linux-2.6.22-20070712.macro/include/asm-mips/sibyte/bcm1480_regs.h linux-2.6.22-20070712/include/asm-mips/sibyte/bcm1480_regs.h
--- linux-2.6.22-20070712.macro/include/asm-mips/sibyte/bcm1480_regs.h	2007-07-12 02:55:37.000000000 +0000
+++ linux-2.6.22-20070712/include/asm-mips/sibyte/bcm1480_regs.h	2007-07-12 14:26:21.000000000 +0000
@@ -220,17 +220,25 @@
 #define A_BCM1480_DUART(chan)               ((((chan)&2) == 0)? A_BCM1480_DUART0 : A_BCM1480_DUART1)
 
 #define BCM1480_DUART_CHANREG_SPACING       0x100
-#define A_BCM1480_DUART_CHANREG(chan,reg)   (A_BCM1480_DUART(chan) \
-                                     + BCM1480_DUART_CHANREG_SPACING*((chan)&1) \
-                                     + (reg))
-#define R_BCM1480_DUART_CHANREG(chan,reg)   (BCM1480_DUART_CHANREG_SPACING*((chan)&1) + (reg))
-
-#define R_BCM1480_DUART_IMRREG(chan)	    (R_DUART_IMR_A + ((chan)&1)*DUART_IMRISR_SPACING)
-#define R_BCM1480_DUART_ISRREG(chan)	    (R_DUART_ISR_A + ((chan)&1)*DUART_IMRISR_SPACING)
-
-#define A_BCM1480_DUART_IMRREG(chan)	    (A_BCM1480_DUART(chan) + R_BCM1480_DUART_IMRREG(chan))
-#define A_BCM1480_DUART_ISRREG(chan)	    (A_BCM1480_DUART(chan) + R_BCM1480_DUART_ISRREG(chan))
-#define A_BCM1480_DUART_IN_PORT(chan)       (A_BCM1480_DUART(chan) + R_DUART_INP_ORT)
+#define A_BCM1480_DUART_CHANREG(chan, reg)				\
+	(A_BCM1480_DUART(chan) +					\
+	 BCM1480_DUART_CHANREG_SPACING * (((chan) & 1) + 1) + (reg))
+#define A_BCM1480_DUART_CTRLREG(chan, reg)				\
+	(A_BCM1480_DUART(chan) +					\
+	 BCM1480_DUART_CHANREG_SPACING * 3 + (reg))
+
+#define R_BCM1480_DUART_IMRREG(chan)					\
+	(R_DUART_IMR_A + ((chan) & 1) * DUART_IMRISR_SPACING)
+#define R_BCM1480_DUART_ISRREG(chan)					\
+	(R_DUART_ISR_A + ((chan) & 1) * DUART_IMRISR_SPACING)
+
+#define A_BCM1480_DUART_IMRREG(chan)					\
+	(A_BCM1480_DUART_CTRLREG((chan), R_BCM1480_DUART_IMRREG(chan)))
+#define A_BCM1480_DUART_ISRREG(chan)					\
+	(A_BCM1480_DUART_CTRLREG((chan), R_BCM1480_DUART_ISRREG(chan)))
+
+#define A_BCM1480_DUART_IN_PORT(chan)					\
+	(A_BCM1480_DUART_CTRLREG((chan), R_DUART_IN_PORT))
 
 /*
  * These constants are the absolute addresses.
diff -up --recursive --new-file linux-2.6.22-20070712.macro/include/asm-mips/sibyte/sb1250_regs.h linux-2.6.22-20070712/include/asm-mips/sibyte/sb1250_regs.h
--- linux-2.6.22-20070712.macro/include/asm-mips/sibyte/sb1250_regs.h	2007-07-12 02:55:37.000000000 +0000
+++ linux-2.6.22-20070712/include/asm-mips/sibyte/sb1250_regs.h	2007-07-12 14:26:21.000000000 +0000
@@ -272,59 +272,69 @@
     ********************************************************************* */
 
 
-#if SIBYTE_HDR_FEATURE_1250_112x		/* This MC only on 1250 & 112x */
+#if SIBYTE_HDR_FEATURE_1250_112x    /* This MC only on 1250 & 112x */
 #define R_DUART_NUM_PORTS           2
 
 #define A_DUART                     0x0010060000
 
 #define DUART_CHANREG_SPACING       0x100
-#define A_DUART_CHANREG(chan,reg)   (A_DUART + DUART_CHANREG_SPACING*(chan) + (reg))
-#define R_DUART_CHANREG(chan,reg)   (DUART_CHANREG_SPACING*(chan) + (reg))
+
+#define A_DUART_CHANREG(chan, reg)					\
+	(A_DUART + DUART_CHANREG_SPACING * ((chan) + 1) + (reg))
 #endif	/* 1250 & 112x */
 
-#define R_DUART_MODE_REG_1	    0x100
-#define R_DUART_MODE_REG_2	    0x110
-#define R_DUART_STATUS              0x120
-#define R_DUART_CLK_SEL             0x130
-#define R_DUART_CMD                 0x150
-#define R_DUART_RX_HOLD             0x160
-#define R_DUART_TX_HOLD             0x170
+#define R_DUART_MODE_REG_1	    0x000
+#define R_DUART_MODE_REG_2	    0x010
+#define R_DUART_STATUS		    0x020
+#define R_DUART_CLK_SEL		    0x030
+#define R_DUART_CMD		    0x050
+#define R_DUART_RX_HOLD		    0x060
+#define R_DUART_TX_HOLD		    0x070
 
 #if SIBYTE_HDR_FEATURE(1250, PASS2) || SIBYTE_HDR_FEATURE(112x, PASS1) || SIBYTE_HDR_FEATURE_CHIP(1480)
-#define R_DUART_FULL_CTL	    0x140
-#define R_DUART_OPCR_X		    0x180
-#define R_DUART_AUXCTL_X	    0x190
-#endif /* 1250 PASS2 || 112x PASS1 || 1480*/
+#define R_DUART_FULL_CTL	    0x040
+#define R_DUART_OPCR_X		    0x080
+#define R_DUART_AUXCTL_X	    0x090
+#endif /* 1250 PASS2 || 112x PASS1 || 1480 */
 
 
 /*
  * The IMR and ISR can't be addressed with A_DUART_CHANREG,
- * so use this macro instead.
+ * so use these macros instead.
  */
 
-#define R_DUART_AUX_CTRL            0x310
-#define R_DUART_ISR_A               0x320
-#define R_DUART_IMR_A               0x330
-#define R_DUART_ISR_B               0x340
-#define R_DUART_IMR_B               0x350
-#define R_DUART_OUT_PORT            0x360
-#define R_DUART_OPCR                0x370
-#define R_DUART_IN_PORT             0x380
-
-#define R_DUART_SET_OPR		    0x3B0
-#define R_DUART_CLEAR_OPR	    0x3C0
-
-#define DUART_IMRISR_SPACING        0x20
-
-#if SIBYTE_HDR_FEATURE_1250_112x		/* This MC only on 1250 & 112x */
-#define R_DUART_IMRREG(chan)	    (R_DUART_IMR_A + (chan)*DUART_IMRISR_SPACING)
-#define R_DUART_ISRREG(chan)	    (R_DUART_ISR_A + (chan)*DUART_IMRISR_SPACING)
-
-#define A_DUART_IMRREG(chan)	    (A_DUART + R_DUART_IMRREG(chan))
-#define A_DUART_ISRREG(chan)	    (A_DUART + R_DUART_ISRREG(chan))
+#if SIBYTE_HDR_FEATURE_1250_112x    /* This MC only on 1250 & 112x */
+#define DUART_IMRISR_SPACING	    0x20
+#define DUART_INCHNG_SPACING	    0x10
+
+#define A_DUART_CTRLREG(reg)						\
+	(A_DUART + DUART_CHANREG_SPACING * 3 + (reg))
+
+#define R_DUART_IMRREG(chan)						\
+	(R_DUART_IMR_A + (chan) * DUART_IMRISR_SPACING)
+#define R_DUART_ISRREG(chan)						\
+	(R_DUART_ISR_A + (chan) * DUART_IMRISR_SPACING)
+#define R_DUART_INCHREG(chan)						\
+	(R_DUART_IN_CHNG_A + (chan) * DUART_INCHNG_SPACING)
+
+#define A_DUART_IMRREG(chan)	    A_DUART_CTRLREG(R_DUART_IMRREG(chan))
+#define A_DUART_ISRREG(chan)	    A_DUART_CTRLREG(R_DUART_ISRREG(chan))
+#define A_DUART_INCHREG(chan)	    A_DUART_CTRLREG(R_DUART_INCHREG(chan))
 #endif	/* 1250 & 112x */
 
-
+#define R_DUART_AUX_CTRL	    0x010
+#define R_DUART_ISR_A		    0x020
+#define R_DUART_IMR_A		    0x030
+#define R_DUART_ISR_B		    0x040
+#define R_DUART_IMR_B		    0x050
+#define R_DUART_OUT_PORT	    0x060
+#define R_DUART_OPCR		    0x070
+#define R_DUART_IN_PORT		    0x080
+
+#define R_DUART_SET_OPR		    0x0B0
+#define R_DUART_CLEAR_OPR	    0x0C0
+#define R_DUART_IN_CHNG_A	    0x0D0
+#define R_DUART_IN_CHNG_B	    0x0E0
 
 
 /*
diff -up --recursive --new-file linux-2.6.22-20070712.macro/include/asm-mips/sibyte/sb1250_uart.h linux-2.6.22-20070712/include/asm-mips/sibyte/sb1250_uart.h
--- linux-2.6.22-20070712.macro/include/asm-mips/sibyte/sb1250_uart.h	2007-07-12 02:55:37.000000000 +0000
+++ linux-2.6.22-20070712/include/asm-mips/sibyte/sb1250_uart.h	2007-07-12 14:26:21.000000000 +0000
@@ -75,7 +75,8 @@
 #define V_DUART_PARITY_MODE_ADD_FIXED V_DUART_PARITY_MODE(K_DUART_PARITY_MODE_ADD_FIXED)
 #define V_DUART_PARITY_MODE_NONE      V_DUART_PARITY_MODE(K_DUART_PARITY_MODE_NONE)
 
-#define M_DUART_ERR_MODE            _SB_MAKEMASK1(5)    /* must be zero */
+#define M_DUART_TX_IRQ_SEL_TXRDY    0
+#define M_DUART_TX_IRQ_SEL_TXEMPT   _SB_MAKEMASK1(5)
 
 #define M_DUART_RX_IRQ_SEL_RXRDY    0
 #define M_DUART_RX_IRQ_SEL_RXFULL   _SB_MAKEMASK1(6)
@@ -246,10 +247,13 @@
 
 #define M_DUART_ISR_BRK_A           _SB_MAKEMASK1(2)
 #define M_DUART_ISR_IN_A            _SB_MAKEMASK1(3)
+#define M_DUART_ISR_ALL_A	    _SB_MAKEMASK(4,0)
+
 #define M_DUART_ISR_TX_B            _SB_MAKEMASK1(4)
 #define M_DUART_ISR_RX_B            _SB_MAKEMASK1(5)
 #define M_DUART_ISR_BRK_B           _SB_MAKEMASK1(6)
 #define M_DUART_ISR_IN_B            _SB_MAKEMASK1(7)
+#define M_DUART_ISR_ALL_B	    _SB_MAKEMASK(4,4)
 
 /*
  * DUART Channel A Interrupt Status Register (Table 10-17)
@@ -262,6 +266,7 @@
 #define M_DUART_ISR_RX              _SB_MAKEMASK1(1)
 #define M_DUART_ISR_BRK             _SB_MAKEMASK1(2)
 #define M_DUART_ISR_IN              _SB_MAKEMASK1(3)
+#define M_DUART_ISR_ALL		    _SB_MAKEMASK(4,0)
 #define M_DUART_ISR_RESERVED        _SB_MAKEMASK(4,4)
 
 /*
diff -up --recursive --new-file linux-2.6.22-20070712.macro/include/linux/serial_core.h linux-2.6.22-20070712/include/linux/serial_core.h
--- linux-2.6.22-20070712.macro/include/linux/serial_core.h	2007-07-12 02:55:45.000000000 +0000
+++ linux-2.6.22-20070712/include/linux/serial_core.h	2007-07-12 14:30:44.000000000 +0000
@@ -142,6 +142,9 @@
 /* Micrel KS8695 */
 #define PORT_KS8695	76
 
+/* Broadcom SB1250, etc. SOC */
+#define PORT_SB1250_DUART	77
+
 
 #ifdef __KERNEL__
 

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Ralf Baechle]

On Thu, Jul 12, 2007 at 06:39:00PM +0100, Maciej W. Rozycki wrote:

>  This is a driver for the SB1250 DUART, a dual serial port implementation 
> included in the Broadcom family of SOCs descending from the SiByte SB1250 
> MIPS64 chip multiprocessor.  It is a new implementation replacing the 
> old-fashioned driver currently present in the linux-mips.org tree.  It 
> supports all the usual features one would expect from a(n asynchronous) 
> serial driver, including modem line control (as far as hardware supports 
> it -- there is edge detection logic missing from the DCD and RI lines and 
> the driver does not implement polling of these lines at the moment), the 
> serial console, BREAK transmission and reception, including the magic 
> SysRq.  The receive FIFO threshold is not maintained though.
> 
> Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>

I'm all in favor of this patch sine the old drivers/char/ serial driver
has been slowly decaying while the kernel around it is changing.  It would
also make the kernel.org kernel finally usable for the Sibyte machines, so
it's an improvment even if it doesn't have half a decade of testing under
the belt, thus ACK.

  Ralf

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Andy Whitcroft]

Maciej W. Rozycki wrote:
>  This is a driver for the SB1250 DUART, a dual serial port implementation 
> included in the Broadcom family of SOCs descending from the SiByte SB1250 
> MIPS64 chip multiprocessor.  It is a new implementation replacing the 
> old-fashioned driver currently present in the linux-mips.org tree.  It 
> supports all the usual features one would expect from a(n asynchronous) 
> serial driver, including modem line control (as far as hardware supports 
> it -- there is edge detection logic missing from the DCD and RI lines and 
> the driver does not implement polling of these lines at the moment), the 
> serial console, BREAK transmission and reception, including the magic 
> SysRq.  The receive FIFO threshold is not maintained though.
> 
> Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
> ---
> Hi,
> 
>  The driver was tested with a SWARM board which uses a BCM1250 SOC (which 
> is dual MIPS64 CMP) and has both ports of the single DUART implemented 
> wired externally.  Both were tested.  Testing included using the ports as 
> terminal lines at 1200bps (which is the ports minimum), 115200bps and a 
> couple of random speeds inbetween.  The modem lines were verified to 
> operate correctly.  No testing was performed with a use as a network 
> interface, like with SLIP or PPP.
> 
>  The driver builds succesfully and without warnings both as integrated and 
> as modular.  There are a couple of -W warnings, but they are results of 
> some inconsistencies (signedness mismatches) in the serial core.  It 
> produces no sparse warnings.  There are a few benign warnings from 
> patchcheck.pl, one of which is, I believe, a bug in the script itself 
> (maintainers cc-ed):
> 
> printk() should include KERN_ facility level
> #750: FILE: drivers/serial/sb1250-duart.c:675:
> +		printk(err);

Heh, yeah Ingo pointed this style out.  This is a wrapper where the
facility will be supplied by the caller (I assume).  The thought there
was that only complain on printks which had a string literal as their
first arguement.  That gets us very high accuracy and eliminates these
falsies.

> 
> The <asm/io.h> warning is, I gather, not a problem and warnings about the 
> _SB_MAKEMASK() macro should be addressed as a separate change.

I think I tend to agree that the MAKEMASK ones are separate.  Good to
see someone using their common sense in the face of whinging by the tool.

You will be pleased to know that the latest version of the tool is
throwing a new batch of errors on your patch :)  Included at the end of
the email.

>  The driver runs correctly with a 64-bit SMP kernel in a big- and 
> little-endian configuration (with spinlock debugging enabled).  Modular 
> configuration was not tested at the run time.  UP configuration was not 
> tested at all, but is not expected to give any troubles.
> 
>  I have asked for testing at the linux-mips list, but rather than results 
> I have received some pressure to push the patch regardless.  So here it 
> goes. ;-)

-apw

WARNING: declaring multiple variables together should be avoided
#372: FILE: drivers/serial/sb1250-duart.c:246:
+	unsigned int mctrl, status;

WARNING: declaring multiple variables together should be avoided
#386: FILE: drivers/serial/sb1250-duart.c:260:
+	unsigned int clr = 0, set = 0, mode2;

WARNING: declaring multiple variables together should be avoided
#464: FILE: drivers/serial/sb1250-duart.c:338:
+	unsigned int status, ch, flag;

WARNING: declaring multiple variables together should be avoided
#667: FILE: drivers/serial/sb1250-duart.c:541:
+	unsigned int mode1 = 0, mode2 = 0, aux = 0;

WARNING: declaring multiple variables together should be avoided
#668: FILE: drivers/serial/sb1250-duart.c:542:
+	unsigned int mode1mask = 0, mode2mask = 0, auxmask = 0;

WARNING: declaring multiple variables together should be avoided
#669: FILE: drivers/serial/sb1250-duart.c:543:
+	unsigned int oldmode1, oldmode2, oldaux;

WARNING: declaring multiple variables together should be avoided
#670: FILE: drivers/serial/sb1250-duart.c:544:
+	unsigned int baud, brg;

WARNING: declaring multiple variables together should be avoided
#907: FILE: drivers/serial/sb1250-duart.c:781:
+	int chip, side;

WARNING: declaring multiple variables together should be avoided
#908: FILE: drivers/serial/sb1250-duart.c:782:
+	int max_lines, line;

WARNING: declaring multiple variables together should be avoided
#1060: FILE: drivers/serial/sb1250-duart.c:934:
+	int i, ret;

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Maciej W. Rozycki]

On Thu, 12 Jul 2007, Andy Whitcroft wrote:

> > printk() should include KERN_ facility level
> > #750: FILE: drivers/serial/sb1250-duart.c:675:
> > +		printk(err);
> 
> Heh, yeah Ingo pointed this style out.  This is a wrapper where the
> facility will be supplied by the caller (I assume).  The thought there

 Actually "err" is "static const char *", except it is used twice in the 
function, so rather than cluttering the source with two identical strings 
and relying on GCC merging them I did it explicitly.

> was that only complain on printks which had a string literal as their
> first arguement.  That gets us very high accuracy and eliminates these
> falsies.

 That would be my suggestion too, if you asked me.  But as did not, I do 
not either.

> I think I tend to agree that the MAKEMASK ones are separate.  Good to
> see someone using their common sense in the face of whinging by the tool.

 Thanks for appreciation. ;-)

> WARNING: declaring multiple variables together should be avoided
> #372: FILE: drivers/serial/sb1250-duart.c:246:
> +	unsigned int mctrl, status;

 Well, this is probably superfluous -- why would anyone prefer:

	int r0;
	int r1;
	int r2;
	int r3;
	int r4;

to:

	int r0, r1, r2, r3, r4;

unconditionally?  I agree clustering variable declarations may obfuscate 
the code, but then again, a bit of common sense should be used.  It 
usually makes sense to group related variables together and declare other 
ones separately.

 And obviously if somebody writes unreadable code, then it is hard to 
change the habit with a script no matter how much you try.

  Maciej

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Andrew Morton]

On Thu, 12 Jul 2007 18:39:00 +0100 (BST)
"Maciej W. Rozycki" <macro@linux-mips.org> wrote:

>  This is a driver for the SB1250 DUART, a dual serial port implementation 
> included in the Broadcom family of SOCs descending from the SiByte SB1250 
> MIPS64 chip multiprocessor.  It is a new implementation replacing the 
> old-fashioned driver currently present in the linux-mips.org tree.  It 
> supports all the usual features one would expect from a(n asynchronous) 
> serial driver, including modem line control (as far as hardware supports 
> it -- there is edge detection logic missing from the DCD and RI lines and 
> the driver does not implement polling of these lines at the moment), the 
> serial console, BREAK transmission and reception, including the magic 
> SysRq.  The receive FIFO threshold is not maintained though.
> 
> ...
>
> +
> +#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
> +#include <asm/sibyte/bcm1480_regs.h>
> +#include <asm/sibyte/bcm1480_int.h>
> +
> +#define SBD_CHANREGS(line)	A_BCM1480_DUART_CHANREG((line), 0)
> +#define SBD_CTRLREGS(line)	A_BCM1480_DUART_CTRLREG((line), 0)
> +#define SBD_INT(line)		(K_BCM1480_INT_UART_0 + (line))
> +
> +#elif defined(CONFIG_SIBYTE_SB1250) || defined(CONFIG_SIBYTE_BCM112X)
> +#include <asm/sibyte/sb1250_regs.h>
> +#include <asm/sibyte/sb1250_int.h>
> +
> +#define SBD_CHANREGS(line)	A_DUART_CHANREG((line), 0)
> +#define SBD_CTRLREGS(line)	A_DUART_CTRLREG(0)
> +#define SBD_INT(line)		(K_INT_UART_0 + (line))
> +
> +#else
> +#error invalid SB1250 UART configuration
> +
> +#endif

If the #error can trigger, the Kconfig is broken, yes?  (No action is
required though - it's always good to have checks)

> +#define to_sport(uport) container_of(uport, struct sbd_port, port)

That didn't need to be implemented as a macro.

> +#define __unused __attribute__((__unused__))

Please use the generic implementations here.  `grep unused
include/linux/compiler*.h'.

> +/*
> + * In bug 1956, we get glitches that can mess up uart registers.  This
> + * "read-mode-reg after any register access" is an accepted workaround.
> + */

<looks in bugzilla.kernel.org>

<wonders how a uart driver can fix an smbfs bug>

Perhaps a reference to where that bug number came from?

> +static void __war_sbd1956(struct sbd_port *sport)
> +{
> +	__read_sbdchn(sport, R_DUART_MODE_REG_1);
> +	__read_sbdchn(sport, R_DUART_MODE_REG_2);
> +}
>
> ...
>
> +static struct uart_ops sbd_ops = {

I suppose if we made this const, something would blow up.




There is no power management support in this driver.

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Alistair John Strachan]

On Thursday 12 July 2007 19:16:20 Maciej W. Rozycki wrote:
> On Thu, 12 Jul 2007, Andy Whitcroft wrote:
[snip]
> > WARNING: declaring multiple variables together should be avoided
> > #372: FILE: drivers/serial/sb1250-duart.c:246:
> > +	unsigned int mctrl, status;
>
>  Well, this is probably superfluous -- why would anyone prefer:
>
> 	int r0;
> 	int r1;
> 	int r2;
> 	int r3;
> 	int r4;
>
> to:
>
> 	int r0, r1, r2, r3, r4;
>
> unconditionally?

Imagine you're working on a piece of kernel code that has a lot of parallel 
churn. Conflicts on lines like "int a,b,c,d;" are more likely to cause Andrew 
et al pain, which I guess is the rationale for discouraging it. Conversely, 
if the variables are kept separate, diff handles it fine.

I think as long as the variables are logically grouped, the pain is minimised, 
but there's a few good reasons for the verbose style.

-- 
Cheers,
Alistair.

137/1 Warrender Park Road, Edinburgh, UK.

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Andrew Morton]

On Thu, 12 Jul 2007 20:15:11 +0100
Alistair John Strachan <alistair@devzero.co.uk> wrote:

> On Thursday 12 July 2007 19:16:20 Maciej W. Rozycki wrote:
> > On Thu, 12 Jul 2007, Andy Whitcroft wrote:
> [snip]
> > > WARNING: declaring multiple variables together should be avoided
> > > #372: FILE: drivers/serial/sb1250-duart.c:246:
> > > +	unsigned int mctrl, status;
> >
> >  Well, this is probably superfluous -- why would anyone prefer:
> >
> > 	int r0;
> > 	int r1;
> > 	int r2;
> > 	int r3;
> > 	int r4;
> >
> > to:
> >
> > 	int r0, r1, r2, r3, r4;
> >
> > unconditionally?
> 
> Imagine you're working on a piece of kernel code that has a lot of parallel 
> churn. Conflicts on lines like "int a,b,c,d;" are more likely to cause Andrew 
> et al pain, which I guess is the rationale for discouraging it. Conversely, 
> if the variables are kept separate, diff handles it fine.

That, plus the first style leaves room for useful code comments.  The lack
of which is often a maintainability bug.

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Andrew Sharp]

On Thu, 12 Jul 2007 11:47:12 -0700 Andrew Morton
<akpm@linux-foundation.org> wrote:

> On Thu, 12 Jul 2007 18:39:00 +0100 (BST)
> "Maciej W. Rozycki" <macro@linux-mips.org> wrote:
> 
> >  This is a driver for the SB1250 DUART, a dual serial port
> > implementation included in the Broadcom family of SOCs descending
> > from the SiByte SB1250 MIPS64 chip multiprocessor.  It is a new
> > implementation replacing the old-fashioned driver currently present
> > in the linux-mips.org tree.  It supports all the usual features one
> > would expect from a(n asynchronous) serial driver, including modem
> > line control (as far as hardware supports it -- there is edge
> > detection logic missing from the DCD and RI lines and the driver
> > does not implement polling of these lines at the moment), the
> > serial console, BREAK transmission and reception, including the
> > magic SysRq.  The receive FIFO threshold is not maintained though.
> > 
> > ...
> >
> > +
> > +#if defined(CONFIG_SIBYTE_BCM1x55) ||
> > defined(CONFIG_SIBYTE_BCM1x80) +#include <asm/sibyte/bcm1480_regs.h>
> > +#include <asm/sibyte/bcm1480_int.h>
> > +
> > +#define SBD_CHANREGS(line)	A_BCM1480_DUART_CHANREG((line),
> > 0) +#define SBD_CTRLREGS(line)
> > A_BCM1480_DUART_CTRLREG((line), 0) +#define
> > SBD_INT(line)		(K_BCM1480_INT_UART_0 + (line)) +
> > +#elif defined(CONFIG_SIBYTE_SB1250) ||
> > defined(CONFIG_SIBYTE_BCM112X) +#include <asm/sibyte/sb1250_regs.h>
> > +#include <asm/sibyte/sb1250_int.h>
> > +
> > +#define SBD_CHANREGS(line)	A_DUART_CHANREG((line), 0)
> > +#define SBD_CTRLREGS(line)	A_DUART_CTRLREG(0)
> > +#define SBD_INT(line)		(K_INT_UART_0 + (line))
> > +
> > +#else
> > +#error invalid SB1250 UART configuration
> > +
> > +#endif
> 
> If the #error can trigger, the Kconfig is broken, yes?  (No action is
> required though - it's always good to have checks)
> 
> > +#define to_sport(uport) container_of(uport, struct sbd_port, port)
> 
> That didn't need to be implemented as a macro.
> 
> > +#define __unused __attribute__((__unused__))
> 
> Please use the generic implementations here.  `grep unused
> include/linux/compiler*.h'.
> 
> > +/*
> > + * In bug 1956, we get glitches that can mess up uart registers.
> > This
> > + * "read-mode-reg after any register access" is an accepted
> > workaround.
> > + */
> 
> <looks in bugzilla.kernel.org>
> 
> <wonders how a uart driver can fix an smbfs bug>
> 
> Perhaps a reference to where that bug number came from?

It's a Sibyte errata/WAR number as I recall.

> > +static void __war_sbd1956(struct sbd_port *sport)
> > +{
> > +	__read_sbdchn(sport, R_DUART_MODE_REG_1);
> > +	__read_sbdchn(sport, R_DUART_MODE_REG_2);
> > +}
> >
> > ...
> >
> > +static struct uart_ops sbd_ops = {
> 
> I suppose if we made this const, something would blow up.
> 
> 
> 
> 
> There is no power management support in this driver.
> 

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Maciej W. Rozycki]

On Thu, 12 Jul 2007, Andrew Morton wrote:

> On Thu, 12 Jul 2007 18:39:00 +0100 (BST)
> "Maciej W. Rozycki" <macro@linux-mips.org> wrote:
> 
> >  This is a driver for the SB1250 DUART, a dual serial port implementation 
> > included in the Broadcom family of SOCs descending from the SiByte SB1250 
> > MIPS64 chip multiprocessor.  It is a new implementation replacing the 
> > old-fashioned driver currently present in the linux-mips.org tree.  It 
> > supports all the usual features one would expect from a(n asynchronous) 
> > serial driver, including modem line control (as far as hardware supports 
> > it -- there is edge detection logic missing from the DCD and RI lines and 
> > the driver does not implement polling of these lines at the moment), the 
> > serial console, BREAK transmission and reception, including the magic 
> > SysRq.  The receive FIFO threshold is not maintained though.
> > 
> > ...
> >
> > +
> > +#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
> > +#include <asm/sibyte/bcm1480_regs.h>
> > +#include <asm/sibyte/bcm1480_int.h>
> > +
> > +#define SBD_CHANREGS(line)	A_BCM1480_DUART_CHANREG((line), 0)
> > +#define SBD_CTRLREGS(line)	A_BCM1480_DUART_CTRLREG((line), 0)
> > +#define SBD_INT(line)		(K_BCM1480_INT_UART_0 + (line))
> > +
> > +#elif defined(CONFIG_SIBYTE_SB1250) || defined(CONFIG_SIBYTE_BCM112X)
> > +#include <asm/sibyte/sb1250_regs.h>
> > +#include <asm/sibyte/sb1250_int.h>
> > +
> > +#define SBD_CHANREGS(line)	A_DUART_CHANREG((line), 0)
> > +#define SBD_CTRLREGS(line)	A_DUART_CTRLREG(0)
> > +#define SBD_INT(line)		(K_INT_UART_0 + (line))
> > +
> > +#else
> > +#error invalid SB1250 UART configuration
> > +
> > +#endif
> 
> If the #error can trigger, the Kconfig is broken, yes?  (No action is
> required though - it's always good to have checks)

 It should not trigger, because to the best of my knowledge all the chip 
variations we support are covered above.  Ultimately, this should become a 
platform device, where this will become a non-issue.  The conditions have 
been copied verbatim from the original driver.

> > +#define to_sport(uport) container_of(uport, struct sbd_port, port)
> 
> That didn't need to be implemented as a macro.

 Like the last time -- everybody seems to implement it as such.  If you 
think that should be changed, I could see if I find some time to grep the 
tree and reimplement all the to_*() macros.

> > +#define __unused __attribute__((__unused__))
> 
> Please use the generic implementations here.  `grep unused
> include/linux/compiler*.h'.

 Any changes there in the last few days?  Hmm, I must have missed them...  
I'll fix it up next week.

> > +/*
> > + * In bug 1956, we get glitches that can mess up uart registers.  This
> > + * "read-mode-reg after any register access" is an accepted workaround.
> > + */
> 
> <looks in bugzilla.kernel.org>
> 
> <wonders how a uart driver can fix an smbfs bug>
> 
> Perhaps a reference to where that bug number came from?

 Again, copied verbatim from the original driver.  It must be a chip 
erratum.  Which is not publicly available, but I think it is still better 
to have it referred to from here than not at all, in case someone wants to 
pester Broadcom about this one.  I can s/bug/erratum/, but I am not sure 
if it won't confuse them then if contacted. ;-)

> > +static void __war_sbd1956(struct sbd_port *sport)
> > +{
> > +	__read_sbdchn(sport, R_DUART_MODE_REG_1);
> > +	__read_sbdchn(sport, R_DUART_MODE_REG_2);
> > +}
> >
> > ...
> >
> > +static struct uart_ops sbd_ops = {
> 
> I suppose if we made this const, something would blow up.

 No problem at the moment -- I'll change it.  Though I have a strong 
suspicion .startup may have to be overridden at the run time at one point 
because of the way the port #1 is wired on the SWARM board (but nowhere 
else) -- the port is shared with a sound device (if it sounds odd, I can 
provide an overview of the hardware configuration).  Then again, perhaps I 
will do it in a different way...

> There is no power management support in this driver.

 Like nowhere in the chip.

  Maciej

Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

[Ralf Baechle]

On Thu, Jul 12, 2007 at 11:47:12AM -0700, Andrew Morton wrote:

> There is no power management support in this driver.

There is hardly anything software could do to safe power on Sibyte SOCs.
Just like most other MIPS SOCs power managment is mostly left to the
hardware which does it by using extensive clockgating and other design
techniques.  As a SW person I can't protest that approach :-)

  Ralf