1 files changed, 1124 insertions, 0 deletions

diff --git a/drivers/serial/sn_console.c b/drivers/serial/sn_console.c
new file mode 100644
index 000000000000..ffaab9b90fd8
--- /dev/null
+++ b/drivers/serial/sn_console.c
@@ -0,0 +1,1124 @@
+/*
+ * C-Brick Serial Port (and console) driver for SGI Altix machines.
+ *
+ * This driver is NOT suitable for talking to the l1-controller for
+ * anything other than 'console activities' --- please use the l1
+ * driver for that.
+ *
+ *
+ * Copyright (c) 2004-2005 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like.  Any license provided herein, whether implied or
+ * otherwise, applies only to this software file.  Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
+ * Mountain View, CA  94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/NoticeExplan
+ */
+
+#include <linux/config.h>
+#include <linux/interrupt.h>
+#include <linux/tty.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/sysrq.h>
+#include <linux/circ_buf.h>
+#include <linux/serial_reg.h>
+#include <linux/delay.h> /* for mdelay */
+#include <linux/miscdevice.h>
+#include <linux/serial_core.h>
+
+#include <asm/io.h>
+#include <asm/sn/simulator.h>
+#include <asm/sn/sn_sal.h>
+
+/* number of characters we can transmit to the SAL console at a time */
+#define SN_SAL_MAX_CHARS 120
+
+/* 64K, when we're asynch, it must be at least printk's LOG_BUF_LEN to
+ * avoid losing chars, (always has to be a power of 2) */
+#define SN_SAL_BUFFER_SIZE (64 * (1 << 10))
+
+#define SN_SAL_UART_FIFO_DEPTH 16
+#define SN_SAL_UART_FIFO_SPEED_CPS 9600/10
+
+/* sn_transmit_chars() calling args */
+#define TRANSMIT_BUFFERED       0
+#define TRANSMIT_RAW            1
+
+/* To use dynamic numbers only and not use the assigned major and minor,
+ * define the following.. */
+                                  /* #define USE_DYNAMIC_MINOR 1 *//* use dynamic minor number */
+#define USE_DYNAMIC_MINOR 0     /* Don't rely on misc_register dynamic minor */
+
+/* Device name we're using */
+#define DEVICE_NAME "ttySG"
+#define DEVICE_NAME_DYNAMIC "ttySG0"    /* need full name for misc_register */
+/* The major/minor we are using, ignored for USE_DYNAMIC_MINOR */
+#define DEVICE_MAJOR 204
+#define DEVICE_MINOR 40
+
+#ifdef CONFIG_MAGIC_SYSRQ
+static char sysrq_serial_str[] = "\eSYS";
+static char *sysrq_serial_ptr = sysrq_serial_str;
+static unsigned long sysrq_requested;
+#endif /* CONFIG_MAGIC_SYSRQ */
+
+/*
+ * Port definition - this kinda drives it all
+ */
+struct sn_cons_port {
+        struct timer_list sc_timer;
+        struct uart_port sc_port;
+        struct sn_sal_ops {
+                int (*sal_puts_raw) (const char *s, int len);
+                int (*sal_puts) (const char *s, int len);
+                int (*sal_getc) (void);
+                int (*sal_input_pending) (void);
+                void (*sal_wakeup_transmit) (struct sn_cons_port *, int);
+        } *sc_ops;
+        unsigned long sc_interrupt_timeout;
+        int sc_is_asynch;
+};
+
+static struct sn_cons_port sal_console_port;
+static int sn_process_input;
+
+/* Only used if USE_DYNAMIC_MINOR is set to 1 */
+static struct miscdevice misc;  /* used with misc_register for dynamic */
+
+extern void early_sn_setup(void);
+
+#undef DEBUG
+#ifdef DEBUG
+static int sn_debug_printf(const char *fmt, ...);
+#define DPRINTF(x...) sn_debug_printf(x)
+#else
+#define DPRINTF(x...) do { } while (0)
+#endif
+
+/* Prototypes */
+static int snt_hw_puts_raw(const char *, int);
+static int snt_hw_puts_buffered(const char *, int);
+static int snt_poll_getc(void);
+static int snt_poll_input_pending(void);
+static int snt_intr_getc(void);
+static int snt_intr_input_pending(void);
+static void sn_transmit_chars(struct sn_cons_port *, int);
+
+/* A table for polling:
+ */
+static struct sn_sal_ops poll_ops = {
+        .sal_puts_raw = snt_hw_puts_raw,
+        .sal_puts = snt_hw_puts_raw,
+        .sal_getc = snt_poll_getc,
+        .sal_input_pending = snt_poll_input_pending
+};
+
+/* A table for interrupts enabled */
+static struct sn_sal_ops intr_ops = {
+        .sal_puts_raw = snt_hw_puts_raw,
+        .sal_puts = snt_hw_puts_buffered,
+        .sal_getc = snt_intr_getc,
+        .sal_input_pending = snt_intr_input_pending,
+        .sal_wakeup_transmit = sn_transmit_chars
+};
+
+/* the console does output in two distinctly different ways:
+ * synchronous (raw) and asynchronous (buffered).  initally, early_printk
+ * does synchronous output.  any data written goes directly to the SAL
+ * to be output (incidentally, it is internally buffered by the SAL)
+ * after interrupts and timers are initialized and available for use,
+ * the console init code switches to asynchronous output.  this is
+ * also the earliest opportunity to begin polling for console input.
+ * after console initialization, console output and tty (serial port)
+ * output is buffered and sent to the SAL asynchronously (either by
+ * timer callback or by UART interrupt) */
+
+/* routines for running the console in polling mode */
+
+/**
+ * snt_poll_getc - Get a character from the console in polling mode
+ *
+ */
+static int snt_poll_getc(void)
+{
+        int ch;
+
+        ia64_sn_console_getc(&ch);
+        return ch;
+}
+
+/**
+ * snt_poll_input_pending - Check if any input is waiting - polling mode.
+ *
+ */
+static int snt_poll_input_pending(void)
+{
+        int status, input;
+
+        status = ia64_sn_console_check(&input);
+        return !status && input;
+}
+
+/* routines for an interrupt driven console (normal) */
+
+/**
+ * snt_intr_getc - Get a character from the console, interrupt mode
+ *
+ */
+static int snt_intr_getc(void)
+{
+        return ia64_sn_console_readc();
+}
+
+/**
+ * snt_intr_input_pending - Check if input is pending, interrupt mode
+ *
+ */
+static int snt_intr_input_pending(void)
+{
+        return ia64_sn_console_intr_status() & SAL_CONSOLE_INTR_RECV;
+}
+
+/* these functions are polled and interrupt */
+
+/**
+ * snt_hw_puts_raw - Send raw string to the console, polled or interrupt mode
+ * @s: String
+ * @len: Length
+ *
+ */
+static int snt_hw_puts_raw(const char *s, int len)
+{
+        /* this will call the PROM and not return until this is done */
+        return ia64_sn_console_putb(s, len);
+}
+
+/**
+ * snt_hw_puts_buffered - Send string to console, polled or interrupt mode
+ * @s: String
+ * @len: Length
+ *
+ */
+static int snt_hw_puts_buffered(const char *s, int len)
+{
+        /* queue data to the PROM */
+        return ia64_sn_console_xmit_chars((char *)s, len);
+}
+
+/* uart interface structs
+ * These functions are associated with the uart_port that the serial core
+ * infrastructure calls.
+ *
+ * Note: Due to how the console works, many routines are no-ops.
+ */
+
+/**
+ * snp_type - What type of console are we?
+ * @port: Port to operate with (we ignore since we only have one port)
+ *
+ */
+static const char *snp_type(struct uart_port *port)
+{
+        return ("SGI SN L1");
+}
+
+/**
+ * snp_tx_empty - Is the transmitter empty?  We pretend we're always empty
+ * @port: Port to operate on (we ignore since we only have one port)
+ *
+ */
+static unsigned int snp_tx_empty(struct uart_port *port)
+{
+        return 1;
+}
+
+/**
+ * snp_stop_tx - stop the transmitter - no-op for us
+ * @port: Port to operat eon - we ignore - no-op function
+ * @tty_stop: Set to 1 if called via uart_stop
+ *
+ */
+static void snp_stop_tx(struct uart_port *port, unsigned int tty_stop)
+{
+}
+
+/**
+ * snp_release_port - Free i/o and resources for port - no-op for us
+ * @port: Port to operate on - we ignore - no-op function
+ *
+ */
+static void snp_release_port(struct uart_port *port)
+{
+}
+
+/**
+ * snp_enable_ms - Force modem status interrupts on - no-op for us
+ * @port: Port to operate on - we ignore - no-op function
+ *
+ */
+static void snp_enable_ms(struct uart_port *port)
+{
+}
+
+/**
+ * snp_shutdown - shut down the port - free irq and disable - no-op for us
+ * @port: Port to shut down - we ignore
+ *
+ */
+static void snp_shutdown(struct uart_port *port)
+{
+}
+
+/**
+ * snp_set_mctrl - set control lines (dtr, rts, etc) - no-op for our console
+ * @port: Port to operate on - we ignore
+ * @mctrl: Lines to set/unset - we ignore
+ *
+ */
+static void snp_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+/**
+ * snp_get_mctrl - get contorl line info, we just return a static value
+ * @port: port to operate on - we only have one port so we ignore this
+ *
+ */
+static unsigned int snp_get_mctrl(struct uart_port *port)
+{
+        return TIOCM_CAR | TIOCM_RNG | TIOCM_DSR | TIOCM_CTS;
+}
+
+/**
+ * snp_stop_rx - Stop the receiver - we ignor ethis
+ * @port: Port to operate on - we ignore
+ *
+ */
+static void snp_stop_rx(struct uart_port *port)
+{
+}
+
+/**
+ * snp_start_tx - Start transmitter
+ * @port: Port to operate on
+ * @tty_stop: Set to 1 if called via uart_start
+ *
+ */
+static void snp_start_tx(struct uart_port *port, unsigned int tty_stop)
+{
+        if (sal_console_port.sc_ops->sal_wakeup_transmit)
+                sal_console_port.sc_ops->sal_wakeup_transmit(&sal_console_port,
+                                                             TRANSMIT_BUFFERED);
+
+}
+
+/**
+ * snp_break_ctl - handle breaks - ignored by us
+ * @port: Port to operate on
+ * @break_state: Break state
+ *
+ */
+static void snp_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+/**
+ * snp_startup - Start up the serial port - always return 0 (We're always on)
+ * @port: Port to operate on
+ *
+ */
+static int snp_startup(struct uart_port *port)
+{
+        return 0;
+}
+
+/**
+ * snp_set_termios - set termios stuff - we ignore these
+ * @port: port to operate on
+ * @termios: New settings
+ * @termios: Old
+ *
+ */
+static void
+snp_set_termios(struct uart_port *port, struct termios *termios,
+                struct termios *old)
+{
+}
+
+/**
+ * snp_request_port - allocate resources for port - ignored by us
+ * @port: port to operate on
+ *
+ */
+static int snp_request_port(struct uart_port *port)
+{
+        return 0;
+}
+
+/**
+ * snp_config_port - allocate resources, set up - we ignore,  we're always on
+ * @port: Port to operate on
+ * @flags: flags used for port setup
+ *
+ */
+static void snp_config_port(struct uart_port *port, int flags)
+{
+}
+
+/* Associate the uart functions above - given to serial core */
+
+static struct uart_ops sn_console_ops = {
+        .tx_empty = snp_tx_empty,
+        .set_mctrl = snp_set_mctrl,
+        .get_mctrl = snp_get_mctrl,
+        .stop_tx = snp_stop_tx,
+        .start_tx = snp_start_tx,
+        .stop_rx = snp_stop_rx,
+        .enable_ms = snp_enable_ms,
+        .break_ctl = snp_break_ctl,
+        .startup = snp_startup,
+        .shutdown = snp_shutdown,
+        .set_termios = snp_set_termios,
+        .pm = NULL,
+        .type = snp_type,
+        .release_port = snp_release_port,
+        .request_port = snp_request_port,
+        .config_port = snp_config_port,
+        .verify_port = NULL,
+};
+
+/* End of uart struct functions and defines */
+
+#ifdef DEBUG
+
+/**
+ * sn_debug_printf - close to hardware debugging printf
+ * @fmt: printf format
+ *
+ * This is as "close to the metal" as we can get, used when the driver
+ * itself may be broken.
+ *
+ */
+static int sn_debug_printf(const char *fmt, ...)
+{
+        static char printk_buf[1024];
+        int printed_len;
+        va_list args;
+
+        va_start(args, fmt);
+        printed_len = vsnprintf(printk_buf, sizeof(printk_buf), fmt, args);
+
+        if (!sal_console_port.sc_ops) {
+                sal_console_port.sc_ops = &poll_ops;
+                early_sn_setup();
+        }
+        sal_console_port.sc_ops->sal_puts_raw(printk_buf, printed_len);
+
+        va_end(args);
+        return printed_len;
+}
+#endif                          /* DEBUG */
+
+/*
+ * Interrupt handling routines.
+ */
+
+/**
+ * sn_receive_chars - Grab characters, pass them to tty layer
+ * @port: Port to operate on
+ * @regs: Saved registers (needed by uart_handle_sysrq_char)
+ * @flags: irq flags
+ *
+ * Note: If we're not registered with the serial core infrastructure yet,
+ * we don't try to send characters to it...
+ *
+ */
+static void
+sn_receive_chars(struct sn_cons_port *port, struct pt_regs *regs,
+                 unsigned long flags)
+{
+        int ch;
+        struct tty_struct *tty;
+
+        if (!port) {
+                printk(KERN_ERR "sn_receive_chars - port NULL so can't receieve\n");
+                return;
+        }
+
+        if (!port->sc_ops) {
+                printk(KERN_ERR "sn_receive_chars - port->sc_ops  NULL so can't receieve\n");
+                return;
+        }
+
+        if (port->sc_port.info) {
+                /* The serial_core stuffs are initilized, use them */
+                tty = port->sc_port.info->tty;
+        }
+        else {
+                /* Not registered yet - can't pass to tty layer.  */
+                tty = NULL;
+        }
+
+        while (port->sc_ops->sal_input_pending()) {
+                ch = port->sc_ops->sal_getc();
+                if (ch < 0) {
+                        printk(KERN_ERR "sn_console: An error occured while "
+                               "obtaining data from the console (0x%0x)\n", ch);
+                        break;
+                }
+#ifdef CONFIG_MAGIC_SYSRQ
+                if (sysrq_requested) {
+                        unsigned long sysrq_timeout = sysrq_requested + HZ*5;
+
+                        sysrq_requested = 0;
+                        if (ch && time_before(jiffies, sysrq_timeout)) {
+                                spin_unlock_irqrestore(&port->sc_port.lock, flags);
+                                handle_sysrq(ch, regs, NULL);
+                                spin_lock_irqsave(&port->sc_port.lock, flags);
+                                /* ignore actual sysrq command char */
+                                continue;
+                        }
+                }
+                if (ch == *sysrq_serial_ptr) {
+                        if (!(*++sysrq_serial_ptr)) {
+                                sysrq_requested = jiffies;
+                                sysrq_serial_ptr = sysrq_serial_str;
+                        }
+                        /*
+                         * ignore the whole sysrq string except for the
+                         * leading escape
+                         */
+                        if (ch != '\e')
+                                continue;
+                }
+                else
+                        sysrq_serial_ptr = sysrq_serial_str;
+#endif /* CONFIG_MAGIC_SYSRQ */
+
+                /* record the character to pass up to the tty layer */
+                if (tty) {
+                        *tty->flip.char_buf_ptr = ch;
+                        *tty->flip.flag_buf_ptr = TTY_NORMAL;
+                        tty->flip.char_buf_ptr++;
+                        tty->flip.count++;
+                        if (tty->flip.count == TTY_FLIPBUF_SIZE)
+                                break;
+                }
+                port->sc_port.icount.rx++;
+        }
+
+        if (tty)
+                tty_flip_buffer_push(tty);
+}
+
+/**
+ * sn_transmit_chars - grab characters from serial core, send off
+ * @port: Port to operate on
+ * @raw: Transmit raw or buffered
+ *
+ * Note: If we're early, before we're registered with serial core, the
+ * writes are going through sn_sal_console_write because that's how
+ * register_console has been set up.  We currently could have asynch
+ * polls calling this function due to sn_sal_switch_to_asynch but we can
+ * ignore them until we register with the serial core stuffs.
+ *
+ */
+static void sn_transmit_chars(struct sn_cons_port *port, int raw)
+{
+        int xmit_count, tail, head, loops, ii;
+        int result;
+        char *start;
+        struct circ_buf *xmit;
+
+        if (!port)
+                return;
+
+        BUG_ON(!port->sc_is_asynch);
+
+        if (port->sc_port.info) {
+                /* We're initilized, using serial core infrastructure */
+                xmit = &port->sc_port.info->xmit;
+        } else {
+                /* Probably sn_sal_switch_to_asynch has been run but serial core isn't
+                 * initilized yet.  Just return.  Writes are going through
+                 * sn_sal_console_write (due to register_console) at this time.
+                 */
+                return;
+        }
+
+        if (uart_circ_empty(xmit) || uart_tx_stopped(&port->sc_port)) {
+                /* Nothing to do. */
+                return;
+        }
+
+        head = xmit->head;
+        tail = xmit->tail;
+        start = &xmit->buf[tail];
+
+        /* twice around gets the tail to the end of the buffer and
+         * then to the head, if needed */
+        loops = (head < tail) ? 2 : 1;
+
+        for (ii = 0; ii < loops; ii++) {
+                xmit_count = (head < tail) ?
+                    (UART_XMIT_SIZE - tail) : (head - tail);
+
+                if (xmit_count > 0) {
+                        if (raw == TRANSMIT_RAW)
+                                result =
+                                    port->sc_ops->sal_puts_raw(start,
+                                                               xmit_count);
+                        else
+                                result =
+                                    port->sc_ops->sal_puts(start, xmit_count);
+#ifdef DEBUG
+                        if (!result)
+                                DPRINTF("`");
+#endif
+                        if (result > 0) {
+                                xmit_count -= result;
+                                port->sc_port.icount.tx += result;
+                                tail += result;
+                                tail &= UART_XMIT_SIZE - 1;
+                                xmit->tail = tail;
+                                start = &xmit->buf[tail];
+                        }
+                }
+        }
+
+        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+                uart_write_wakeup(&port->sc_port);
+
+        if (uart_circ_empty(xmit))
+                snp_stop_tx(&port->sc_port, 0); /* no-op for us */
+}
+
+/**
+ * sn_sal_interrupt - Handle console interrupts
+ * @irq: irq #, useful for debug statements
+ * @dev_id: our pointer to our port (sn_cons_port which contains the uart port)
+ * @regs: Saved registers, used by sn_receive_chars for uart_handle_sysrq_char
+ *
+ */
+static irqreturn_t sn_sal_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+        struct sn_cons_port *port = (struct sn_cons_port *)dev_id;
+        unsigned long flags;
+        int status = ia64_sn_console_intr_status();
+
+        if (!port)
+                return IRQ_NONE;
+
+        spin_lock_irqsave(&port->sc_port.lock, flags);
+        if (status & SAL_CONSOLE_INTR_RECV) {
+                sn_receive_chars(port, regs, flags);
+        }
+        if (status & SAL_CONSOLE_INTR_XMIT) {
+                sn_transmit_chars(port, TRANSMIT_BUFFERED);
+        }
+        spin_unlock_irqrestore(&port->sc_port.lock, flags);
+        return IRQ_HANDLED;
+}
+
+/**
+ * sn_sal_connect_interrupt - Request interrupt, handled by sn_sal_interrupt
+ * @port: Our sn_cons_port (which contains the uart port)
+ *
+ * returns the console irq if interrupt is successfully registered, else 0
+ *
+ */
+static int sn_sal_connect_interrupt(struct sn_cons_port *port)
+{
+        if (request_irq(SGI_UART_VECTOR, sn_sal_interrupt,
+                        SA_INTERRUPT | SA_SHIRQ,
+                        "SAL console driver", port) >= 0) {
+                return SGI_UART_VECTOR;
+        }
+
+        printk(KERN_INFO "sn_console: console proceeding in polled mode\n");
+        return 0;
+}
+
+/**
+ * sn_sal_timer_poll - this function handles polled console mode
+ * @data: A pointer to our sn_cons_port (which contains the uart port)
+ *
+ * data is the pointer that init_timer will store for us.  This function is
+ * associated with init_timer to see if there is any console traffic.
+ * Obviously not used in interrupt mode
+ *
+ */
+static void sn_sal_timer_poll(unsigned long data)
+{
+        struct sn_cons_port *port = (struct sn_cons_port *)data;
+        unsigned long flags;
+
+        if (!port)
+                return;
+
+        if (!port->sc_port.irq) {
+                spin_lock_irqsave(&port->sc_port.lock, flags);
+                if (sn_process_input)
+                        sn_receive_chars(port, NULL, flags);
+                sn_transmit_chars(port, TRANSMIT_RAW);
+                spin_unlock_irqrestore(&port->sc_port.lock, flags);
+                mod_timer(&port->sc_timer,
+                          jiffies + port->sc_interrupt_timeout);
+        }
+}
+
+/*
+ * Boot-time initialization code
+ */
+
+/**
+ * sn_sal_switch_to_asynch - Switch to async mode (as opposed to synch)
+ * @port: Our sn_cons_port (which contains the uart port)
+ *
+ * So this is used by sn_sal_serial_console_init (early on, before we're
+ * registered with serial core).  It's also used by sn_sal_module_init
+ * right after we've registered with serial core.  The later only happens
+ * if we didn't already come through here via sn_sal_serial_console_init.
+ *
+ */
+static void __init sn_sal_switch_to_asynch(struct sn_cons_port *port)
+{
+        unsigned long flags;
+
+        if (!port)
+                return;
+
+        DPRINTF("sn_console: about to switch to asynchronous console\n");
+
+        /* without early_printk, we may be invoked late enough to race
+         * with other cpus doing console IO at this point, however
+         * console interrupts will never be enabled */
+        spin_lock_irqsave(&port->sc_port.lock, flags);
+
+        /* early_printk invocation may have done this for us */
+        if (!port->sc_ops)
+                port->sc_ops = &poll_ops;
+
+        /* we can't turn on the console interrupt (as request_irq
+         * calls kmalloc, which isn't set up yet), so we rely on a
+         * timer to poll for input and push data from the console
+         * buffer.
+         */
+        init_timer(&port->sc_timer);
+        port->sc_timer.function = sn_sal_timer_poll;
+        port->sc_timer.data = (unsigned long)port;
+
+        if (IS_RUNNING_ON_SIMULATOR())
+                port->sc_interrupt_timeout = 6;
+        else {
+                /* 960cps / 16 char FIFO = 60HZ
+                 * HZ / (SN_SAL_FIFO_SPEED_CPS / SN_SAL_FIFO_DEPTH) */
+                port->sc_interrupt_timeout =
+                    HZ * SN_SAL_UART_FIFO_DEPTH / SN_SAL_UART_FIFO_SPEED_CPS;
+        }
+        mod_timer(&port->sc_timer, jiffies + port->sc_interrupt_timeout);
+
+        port->sc_is_asynch = 1;
+        spin_unlock_irqrestore(&port->sc_port.lock, flags);
+}
+
+/**
+ * sn_sal_switch_to_interrupts - Switch to interrupt driven mode
+ * @port: Our sn_cons_port (which contains the uart port)
+ *
+ * In sn_sal_module_init, after we're registered with serial core and
+ * the port is added, this function is called to switch us to interrupt
+ * mode.  We were previously in asynch/polling mode (using init_timer).
+ *
+ * We attempt to switch to interrupt mode here by calling
+ * sn_sal_connect_interrupt.  If that works out, we enable receive interrupts.
+ */
+static void __init sn_sal_switch_to_interrupts(struct sn_cons_port *port)
+{
+        int irq;
+        unsigned long flags;
+
+        if (!port)
+                return;
+
+        DPRINTF("sn_console: switching to interrupt driven console\n");
+
+        spin_lock_irqsave(&port->sc_port.lock, flags);
+
+        irq = sn_sal_connect_interrupt(port);
+
+        if (irq) {
+                port->sc_port.irq = irq;
+                port->sc_ops = &intr_ops;
+
+                /* turn on receive interrupts */
+                ia64_sn_console_intr_enable(SAL_CONSOLE_INTR_RECV);
+        }
+        spin_unlock_irqrestore(&port->sc_port.lock, flags);
+}
+
+/*
+ * Kernel console definitions
+ */
+
+static void sn_sal_console_write(struct console *, const char *, unsigned);
+static int __init sn_sal_console_setup(struct console *, char *);
+extern struct uart_driver sal_console_uart;
+extern struct tty_driver *uart_console_device(struct console *, int *);
+
+static struct console sal_console = {
+        .name = DEVICE_NAME,
+        .write = sn_sal_console_write,
+        .device = uart_console_device,
+        .setup = sn_sal_console_setup,
+        .index = -1,            /* unspecified */
+        .data = &sal_console_uart,
+};
+
+#define SAL_CONSOLE     &sal_console
+
+struct uart_driver sal_console_uart = {
+        .owner = THIS_MODULE,
+        .driver_name = "sn_console",
+        .dev_name = DEVICE_NAME,
+        .major = 0,             /* major/minor set at registration time per USE_DYNAMIC_MINOR */
+        .minor = 0,
+        .nr = 1,                /* one port */
+        .cons = SAL_CONSOLE,
+};
+
+/**
+ * sn_sal_module_init - When the kernel loads us, get us rolling w/ serial core
+ *
+ * Before this is called, we've been printing kernel messages in a special
+ * early mode not making use of the serial core infrastructure.  When our
+ * driver is loaded for real, we register the driver and port with serial
+ * core and try to enable interrupt driven mode.
+ *
+ */
+static int __init sn_sal_module_init(void)
+{
+        int retval;
+
+        if (!ia64_platform_is("sn2"))
+                return -ENODEV;
+
+        printk(KERN_INFO "sn_console: Console driver init\n");
+
+        if (USE_DYNAMIC_MINOR == 1) {
+                misc.minor = MISC_DYNAMIC_MINOR;
+                misc.name = DEVICE_NAME_DYNAMIC;
+                retval = misc_register(&misc);
+                if (retval != 0) {
+                        printk
+                            ("Failed to register console device using misc_register.\n");
+                        return -ENODEV;
+                }
+                sal_console_uart.major = MISC_MAJOR;
+                sal_console_uart.minor = misc.minor;
+        } else {
+                sal_console_uart.major = DEVICE_MAJOR;
+                sal_console_uart.minor = DEVICE_MINOR;
+        }
+
+        /* We register the driver and the port before switching to interrupts
+         * or async above so the proper uart structures are populated */
+
+        if (uart_register_driver(&sal_console_uart) < 0) {
+                printk
+                    ("ERROR sn_sal_module_init failed uart_register_driver, line %d\n",
+                     __LINE__);
+                return -ENODEV;
+        }
+
+        spin_lock_init(&sal_console_port.sc_port.lock);
+
+        /* Setup the port struct with the minimum needed */
+        sal_console_port.sc_port.membase = (char *)1;   /* just needs to be non-zero */
+        sal_console_port.sc_port.type = PORT_16550A;
+        sal_console_port.sc_port.fifosize = SN_SAL_MAX_CHARS;
+        sal_console_port.sc_port.ops = &sn_console_ops;
+        sal_console_port.sc_port.line = 0;
+
+        if (uart_add_one_port(&sal_console_uart, &sal_console_port.sc_port) < 0) {
+                /* error - not sure what I'd do - so I'll do nothing */
+                printk(KERN_ERR "%s: unable to add port\n", __FUNCTION__);
+        }
+
+        /* when this driver is compiled in, the console initialization
+         * will have already switched us into asynchronous operation
+         * before we get here through the module initcalls */
+        if (!sal_console_port.sc_is_asynch) {
+                sn_sal_switch_to_asynch(&sal_console_port);
+        }
+
+        /* at this point (module_init) we can try to turn on interrupts */
+        if (!IS_RUNNING_ON_SIMULATOR()) {
+                sn_sal_switch_to_interrupts(&sal_console_port);
+        }
+        sn_process_input = 1;
+        return 0;
+}
+
+/**
+ * sn_sal_module_exit - When we're unloaded, remove the driver/port
+ *
+ */
+static void __exit sn_sal_module_exit(void)
+{
+        del_timer_sync(&sal_console_port.sc_timer);
+        uart_remove_one_port(&sal_console_uart, &sal_console_port.sc_port);
+        uart_unregister_driver(&sal_console_uart);
+        misc_deregister(&misc);
+}
+
+module_init(sn_sal_module_init);
+module_exit(sn_sal_module_exit);
+
+/**
+ * puts_raw_fixed - sn_sal_console_write helper for adding \r's as required
+ * @puts_raw : puts function to do the writing
+ * @s: input string
+ * @count: length
+ *
+ * We need a \r ahead of every \n for direct writes through
+ * ia64_sn_console_putb (what sal_puts_raw below actually does).
+ *
+ */
+
+static void puts_raw_fixed(int (*puts_raw) (const char *s, int len),
+                           const char *s, int count)
+{
+        const char *s1;
+
+        /* Output '\r' before each '\n' */
+        while ((s1 = memchr(s, '\n', count)) != NULL) {
+                puts_raw(s, s1 - s);
+                puts_raw("\r\n", 2);
+                count -= s1 + 1 - s;
+                s = s1 + 1;
+        }
+        puts_raw(s, count);
+}
+
+/**
+ * sn_sal_console_write - Print statements before serial core available
+ * @console: Console to operate on - we ignore since we have just one
+ * @s: String to send
+ * @count: length
+ *
+ * This is referenced in the console struct.  It is used for early
+ * console printing before we register with serial core and for things
+ * such as kdb.  The console_lock must be held when we get here.
+ *
+ * This function has some code for trying to print output even if the lock
+ * is held.  We try to cover the case where a lock holder could have died.
+ * We don't use this special case code if we're not registered with serial
+ * core yet.  After we're registered with serial core, the only time this
+ * function would be used is for high level kernel output like magic sys req,
+ * kdb, and printk's.
+ */
+static void
+sn_sal_console_write(struct console *co, const char *s, unsigned count)
+{
+        unsigned long flags = 0;
+        struct sn_cons_port *port = &sal_console_port;
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
+        static int stole_lock = 0;
+#endif
+
+        BUG_ON(!port->sc_is_asynch);
+
+        /* We can't look at the xmit buffer if we're not registered with serial core
+         *  yet.  So only do the fancy recovery after registering
+         */
+        if (port->sc_port.info) {
+
+                /* somebody really wants this output, might be an
+                 * oops, kdb, panic, etc.  make sure they get it. */
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
+                if (spin_is_locked(&port->sc_port.lock)) {
+                        int lhead = port->sc_port.info->xmit.head;
+                        int ltail = port->sc_port.info->xmit.tail;
+                        int counter, got_lock = 0;
+
+                        /*
+                         * We attempt to determine if someone has died with the
+                         * lock. We wait ~20 secs after the head and tail ptrs
+                         * stop moving and assume the lock holder is not functional
+                         * and plow ahead. If the lock is freed within the time out
+                         * period we re-get the lock and go ahead normally. We also
+                         * remember if we have plowed ahead so that we don't have
+                         * to wait out the time out period again - the asumption
+                         * is that we will time out again.
+                         */
+
+                        for (counter = 0; counter < 150; mdelay(125), counter++) {
+                                if (!spin_is_locked(&port->sc_port.lock)
+                                    || stole_lock) {
+                                        if (!stole_lock) {
+                                                spin_lock_irqsave(&port->
+                                                                  sc_port.lock,
+                                                                  flags);
+                                                got_lock = 1;
+                                        }
+                                        break;
+                                } else {
+                                        /* still locked */
+                                        if ((lhead !=
+                                             port->sc_port.info->xmit.head)
+                                            || (ltail !=
+                                                port->sc_port.info->xmit.
+                                                tail)) {
+                                                lhead =
+                                                    port->sc_port.info->xmit.
+                                                    head;
+                                                ltail =
+                                                    port->sc_port.info->xmit.
+                                                    tail;
+                                                counter = 0;
+                                        }
+                                }
+                        }
+                        /* flush anything in the serial core xmit buffer, raw */
+                        sn_transmit_chars(port, 1);
+                        if (got_lock) {
+                                spin_unlock_irqrestore(&port->sc_port.lock,
+                                                       flags);
+                                stole_lock = 0;
+                        } else {
+                                /* fell thru */
+                                stole_lock = 1;
+                        }
+                        puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
+                } else {
+                        stole_lock = 0;
+#endif
+                        spin_lock_irqsave(&port->sc_port.lock, flags);
+                        sn_transmit_chars(port, 1);
+                        spin_unlock_irqrestore(&port->sc_port.lock, flags);
+
+                        puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
+                }
+#endif
+        }
+        else {
+                /* Not yet registered with serial core - simple case */
+                puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
+        }
+}
+
+
+/**
+ * sn_sal_console_setup - Set up console for early printing
+ * @co: Console to work with
+ * @options: Options to set
+ *
+ * Altix console doesn't do anything with baud rates, etc, anyway.
+ *
+ * This isn't required since not providing the setup function in the
+ * console struct is ok.  However, other patches like KDB plop something
+ * here so providing it is easier.
+ *
+ */
+static int __init sn_sal_console_setup(struct console *co, char *options)
+{
+        return 0;
+}
+
+/**
+ * sn_sal_console_write_early - simple early output routine
+ * @co - console struct
+ * @s - string to print
+ * @count - count
+ *
+ * Simple function to provide early output, before even
+ * sn_sal_serial_console_init is called.  Referenced in the
+ * console struct registerd in sn_serial_console_early_setup.
+ *
+ */
+static void __init
+sn_sal_console_write_early(struct console *co, const char *s, unsigned count)
+{
+        puts_raw_fixed(sal_console_port.sc_ops->sal_puts_raw, s, count);
+}
+
+/* Used for very early console printing - again, before
+ * sn_sal_serial_console_init is run */
+static struct console sal_console_early __initdata = {
+        .name = "sn_sal",
+        .write = sn_sal_console_write_early,
+        .flags = CON_PRINTBUFFER,
+        .index = -1,
+};
+
+/**
+ * sn_serial_console_early_setup - Sets up early console output support
+ *
+ * Register a console early on...  This is for output before even
+ * sn_sal_serial_cosnole_init is called.  This function is called from
+ * setup.c.  This allows us to do really early polled writes. When
+ * sn_sal_serial_console_init is called, this console is unregistered
+ * and a new one registered.
+ */
+int __init sn_serial_console_early_setup(void)
+{
+        if (!ia64_platform_is("sn2"))
+                return -1;
+
+        sal_console_port.sc_ops = &poll_ops;
+        early_sn_setup();       /* Find SAL entry points */
+        register_console(&sal_console_early);
+
+        return 0;
+}
+
+/**
+ * sn_sal_serial_console_init - Early console output - set up for register
+ *
+ * This function is called when regular console init happens.  Because we
+ * support even earlier console output with sn_serial_console_early_setup
+ * (called from setup.c directly), this function unregisters the really
+ * early console.
+ *
+ * Note: Even if setup.c doesn't register sal_console_early, unregistering
+ * it here doesn't hurt anything.
+ *
+ */
+static int __init sn_sal_serial_console_init(void)
+{
+        if (ia64_platform_is("sn2")) {
+                sn_sal_switch_to_asynch(&sal_console_port);
+                DPRINTF("sn_sal_serial_console_init : register console\n");
+                register_console(&sal_console);
+                unregister_console(&sal_console_early);
+        }
+        return 0;
+}
+
+console_initcall(sn_sal_serial_console_init);