Linux-2.6.12-rc2

[linux-flexiantxendom0-natty.git] / drivers / serial / sn_console.c

/*
 * 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);