x86: PAT avoid aliasing in /dev/mem read/write

[linux-2.6/mini2440.git] / drivers / char / viocons.c

/* -*- linux-c -*-
 *
 *  drivers/char/viocons.c
 *
 *  iSeries Virtual Terminal
 *
 *  Authors: Dave Boutcher <boutcher@us.ibm.com>
 *           Ryan Arnold <ryanarn@us.ibm.com>
 *           Colin Devilbiss <devilbis@us.ibm.com>
 *           Stephen Rothwell <sfr@au1.ibm.com>
 *
 * (C) Copyright 2000, 2001, 2002, 2003, 2004 IBM 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) anyu later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <linux/errno.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/console.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <asm/ioctls.h>
#include <linux/kd.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/sysrq.h>

#include <asm/firmware.h>
#include <asm/iseries/vio.h>
#include <asm/iseries/hv_lp_event.h>
#include <asm/iseries/hv_call_event.h>
#include <asm/iseries/hv_lp_config.h>
#include <asm/iseries/hv_call.h>

#ifdef CONFIG_VT
#error You must turn off CONFIG_VT to use CONFIG_VIOCONS
#endif

#define VIOTTY_MAGIC (0x0DCB)
#define VTTY_PORTS 10

#define VIOCONS_KERN_WARN       KERN_WARNING "viocons: "
#define VIOCONS_KERN_INFO       KERN_INFO "viocons: "

static DEFINE_SPINLOCK(consolelock);
static DEFINE_SPINLOCK(consoleloglock);

static int vio_sysrq_pressed;

#define VIOCHAR_NUM_BUF         16

/*
 * Our port information.  We store a pointer to one entry in the
 * tty_driver_data
 */
static struct port_info {
        int magic;
        struct tty_struct *tty;
        HvLpIndex lp;
        u8 vcons;
        u64 seq;        /* sequence number of last HV send */
        u64 ack;        /* last ack from HV */
/*
 * When we get writes faster than we can send it to the partition,
 * buffer the data here. Note that used is a bit map of used buffers.
 * It had better have enough bits to hold VIOCHAR_NUM_BUF the bitops assume
 * it is a multiple of unsigned long
 */
        unsigned long used;
        u8 *buffer[VIOCHAR_NUM_BUF];
        int bufferBytes[VIOCHAR_NUM_BUF];
        int curbuf;
        int bufferOverflow;
        int overflowMessage;
} port_info[VTTY_PORTS];

#define viochar_is_console(pi)  ((pi) == &port_info[0])
#define viochar_port(pi)        ((pi) - &port_info[0])

static void initDataEvent(struct viocharlpevent *viochar, HvLpIndex lp);

static struct tty_driver *viotty_driver;

static void hvlog(char *fmt, ...)
{
        int i;
        unsigned long flags;
        va_list args;
        static char buf[256];

        spin_lock_irqsave(&consoleloglock, flags);
        va_start(args, fmt);
        i = vscnprintf(buf, sizeof(buf) - 1, fmt, args);
        va_end(args);
        buf[i++] = '\r';
        HvCall_writeLogBuffer(buf, i);
        spin_unlock_irqrestore(&consoleloglock, flags);
}

static void hvlogOutput(const char *buf, int count)
{
        unsigned long flags;
        int begin;
        int index;
        static const char cr = '\r';

        begin = 0;
        spin_lock_irqsave(&consoleloglock, flags);
        for (index = 0; index < count; index++) {
                if (buf[index] == '\n') {
                        /*
                         * Start right after the last '\n' or at the zeroth
                         * array position and output the number of characters
                         * including the newline.
                         */
                        HvCall_writeLogBuffer(&buf[begin], index - begin + 1);
                        begin = index + 1;
                        HvCall_writeLogBuffer(&cr, 1);
                }
        }
        if ((index - begin) > 0)
                HvCall_writeLogBuffer(&buf[begin], index - begin);
        spin_unlock_irqrestore(&consoleloglock, flags);
}

/*
 * Make sure we're pointing to a valid port_info structure.  Shamelessly
 * plagerized from serial.c
 */
static inline int viotty_paranoia_check(struct port_info *pi,
                                        char *name, const char *routine)
{
        static const char *bad_pi_addr = VIOCONS_KERN_WARN
                "warning: bad address for port_info struct (%s) in %s\n";
        static const char *badmagic = VIOCONS_KERN_WARN
                "warning: bad magic number for port_info struct (%s) in %s\n";

        if ((pi < &port_info[0]) || (viochar_port(pi) > VTTY_PORTS)) {
                printk(bad_pi_addr, name, routine);
                return 1;
        }
        if (pi->magic != VIOTTY_MAGIC) {
                printk(badmagic, name, routine);
                return 1;
        }
        return 0;
}

/*
 * Add data to our pending-send buffers.  
 *
 * NOTE: Don't use printk in here because it gets nastily recursive.
 * hvlog can be used to log to the hypervisor buffer
 */
static int buffer_add(struct port_info *pi, const char *buf, size_t len)
{
        size_t bleft;
        size_t curlen;
        const char *curbuf;
        int nextbuf;

        curbuf = buf;
        bleft = len;
        while (bleft > 0) {
                /*
                 * If there is no space left in the current buffer, we have
                 * filled everything up, so return.  If we filled the previous
                 * buffer we would already have moved to the next one.
                 */
                if (pi->bufferBytes[pi->curbuf] == VIOCHAR_MAX_DATA) {
                        hvlog ("\n\rviocons: No overflow buffer available for memcpy().\n");
                        pi->bufferOverflow++;
                        pi->overflowMessage = 1;
                        break;
                }

                /*
                 * Turn on the "used" bit for this buffer.  If it's already on,
                 * that's fine.
                 */
                set_bit(pi->curbuf, &pi->used);

                /*
                 * See if this buffer has been allocated.  If not, allocate it.
                 */
                if (pi->buffer[pi->curbuf] == NULL) {
                        pi->buffer[pi->curbuf] =
                            kmalloc(VIOCHAR_MAX_DATA, GFP_ATOMIC);
                        if (pi->buffer[pi->curbuf] == NULL) {
                                hvlog("\n\rviocons: kmalloc failed allocating spaces for buffer %d.",
                                        pi->curbuf);
                                break;
                        }
                }

                /* Figure out how much we can copy into this buffer. */
                if (bleft < (VIOCHAR_MAX_DATA - pi->bufferBytes[pi->curbuf]))
                        curlen = bleft;
                else
                        curlen = VIOCHAR_MAX_DATA - pi->bufferBytes[pi->curbuf];

                /* Copy the data into the buffer. */
                memcpy(pi->buffer[pi->curbuf] + pi->bufferBytes[pi->curbuf],
                                curbuf, curlen);

                pi->bufferBytes[pi->curbuf] += curlen;
                curbuf += curlen;
                bleft -= curlen;

                /*
                 * Now see if we've filled this buffer.  If not then
                 * we'll try to use it again later.  If we've filled it
                 * up then we'll advance the curbuf to the next in the
                 * circular queue.
                 */
                if (pi->bufferBytes[pi->curbuf] == VIOCHAR_MAX_DATA) {
                        nextbuf = (pi->curbuf + 1) % VIOCHAR_NUM_BUF;
                        /*
                         * Move to the next buffer if it hasn't been used yet
                         */
                        if (test_bit(nextbuf, &pi->used) == 0)
                                pi->curbuf = nextbuf;
                }
        }
        return len - bleft;
}

/*
 * Send pending data
 *
 * NOTE: Don't use printk in here because it gets nastily recursive.
 * hvlog can be used to log to the hypervisor buffer
 */
static void send_buffers(struct port_info *pi)
{
        HvLpEvent_Rc hvrc;
        int nextbuf;
        struct viocharlpevent *viochar;
        unsigned long flags;

        spin_lock_irqsave(&consolelock, flags);

        viochar = (struct viocharlpevent *)
            vio_get_event_buffer(viomajorsubtype_chario);

        /* Make sure we got a buffer */
        if (viochar == NULL) {
                hvlog("\n\rviocons: Can't get viochar buffer in sendBuffers().");
                spin_unlock_irqrestore(&consolelock, flags);
                return;
        }

        if (pi->used == 0) {
                hvlog("\n\rviocons: in sendbuffers(), but no buffers used.\n");
                vio_free_event_buffer(viomajorsubtype_chario, viochar);
                spin_unlock_irqrestore(&consolelock, flags);
                return;
        }

        /*
         * curbuf points to the buffer we're filling.  We want to
         * start sending AFTER this one.  
         */
        nextbuf = (pi->curbuf + 1) % VIOCHAR_NUM_BUF;

        /*
         * Loop until we find a buffer with the used bit on
         */
        while (test_bit(nextbuf, &pi->used) == 0)
                nextbuf = (nextbuf + 1) % VIOCHAR_NUM_BUF;

        initDataEvent(viochar, pi->lp);

        /*
         * While we have buffers with data, and our send window
         * is open, send them
         */
        while ((test_bit(nextbuf, &pi->used)) &&
               ((pi->seq - pi->ack) < VIOCHAR_WINDOW)) {
                viochar->len = pi->bufferBytes[nextbuf];
                viochar->event.xCorrelationToken = pi->seq++;
                viochar->event.xSizeMinus1 =
                        offsetof(struct viocharlpevent, data) + viochar->len;

                memcpy(viochar->data, pi->buffer[nextbuf], viochar->len);

                hvrc = HvCallEvent_signalLpEvent(&viochar->event);
                if (hvrc) {
                        /*
                         * MUST unlock the spinlock before doing a printk
                         */
                        vio_free_event_buffer(viomajorsubtype_chario, viochar);
                        spin_unlock_irqrestore(&consolelock, flags);

                        printk(VIOCONS_KERN_WARN
                               "error sending event! return code %d\n",
                               (int)hvrc);
                        return;
                }

                /*
                 * clear the used bit, zero the number of bytes in
                 * this buffer, and move to the next buffer
                 */
                clear_bit(nextbuf, &pi->used);
                pi->bufferBytes[nextbuf] = 0;
                nextbuf = (nextbuf + 1) % VIOCHAR_NUM_BUF;
        }

        /*
         * If we have emptied all the buffers, start at 0 again.
         * this will re-use any allocated buffers
         */
        if (pi->used == 0) {
                pi->curbuf = 0;

                if (pi->overflowMessage)
                        pi->overflowMessage = 0;

                if (pi->tty) {
                        tty_wakeup(pi->tty);
                }
        }

        vio_free_event_buffer(viomajorsubtype_chario, viochar);
        spin_unlock_irqrestore(&consolelock, flags);
}

/*
 * Our internal writer.  Gets called both from the console device and
 * the tty device.  the tty pointer will be NULL if called from the console.
 * Return total number of bytes "written".
 *
 * NOTE: Don't use printk in here because it gets nastily recursive.  hvlog
 * can be used to log to the hypervisor buffer
 */
static int internal_write(struct port_info *pi, const char *buf, size_t len)
{
        HvLpEvent_Rc hvrc;
        size_t bleft;
        size_t curlen;
        const char *curbuf;
        unsigned long flags;
        struct viocharlpevent *viochar;

        /*
         * Write to the hvlog of inbound data are now done prior to
         * calling internal_write() since internal_write() is only called in
         * the event that an lp event path is active, which isn't the case for
         * logging attempts prior to console initialization.
         *
         * If there is already data queued for this port, send it prior to
         * attempting to send any new data.
         */
        if (pi->used)
                send_buffers(pi);

        spin_lock_irqsave(&consolelock, flags);

        viochar = vio_get_event_buffer(viomajorsubtype_chario);
        if (viochar == NULL) {
                spin_unlock_irqrestore(&consolelock, flags);
                hvlog("\n\rviocons: Can't get vio buffer in internal_write().");
                return -EAGAIN;
        }
        initDataEvent(viochar, pi->lp);

        curbuf = buf;
        bleft = len;

        while ((bleft > 0) && (pi->used == 0) &&
               ((pi->seq - pi->ack) < VIOCHAR_WINDOW)) {
                if (bleft > VIOCHAR_MAX_DATA)
                        curlen = VIOCHAR_MAX_DATA;
                else
                        curlen = bleft;

                viochar->event.xCorrelationToken = pi->seq++;
                memcpy(viochar->data, curbuf, curlen);
                viochar->len = curlen;
                viochar->event.xSizeMinus1 =
                    offsetof(struct viocharlpevent, data) + curlen;

                hvrc = HvCallEvent_signalLpEvent(&viochar->event);
                if (hvrc) {
                        hvlog("viocons: error sending event! %d\n", (int)hvrc);
                        goto out;
                }
                curbuf += curlen;
                bleft -= curlen;
        }

        /* If we didn't send it all, buffer as much of it as we can. */
        if (bleft > 0)
                bleft -= buffer_add(pi, curbuf, bleft);
out:
        vio_free_event_buffer(viomajorsubtype_chario, viochar);
        spin_unlock_irqrestore(&consolelock, flags);
        return len - bleft;
}

static struct port_info *get_port_data(struct tty_struct *tty)
{
        unsigned long flags;
        struct port_info *pi;

        spin_lock_irqsave(&consolelock, flags);
        if (tty) {
                pi = (struct port_info *)tty->driver_data;
                if (!pi || viotty_paranoia_check(pi, tty->name,
                                             "get_port_data")) {
                        pi = NULL;
                }
        } else
                /*
                 * If this is the console device, use the lp from
                 * the first port entry
                 */
                pi = &port_info[0];
        spin_unlock_irqrestore(&consolelock, flags);
        return pi;
}

/*
 * Initialize the common fields in a charLpEvent
 */
static void initDataEvent(struct viocharlpevent *viochar, HvLpIndex lp)
{
        struct HvLpEvent *hev = &viochar->event;

        memset(viochar, 0, sizeof(struct viocharlpevent));

        hev->flags = HV_LP_EVENT_VALID | HV_LP_EVENT_DEFERRED_ACK |
                HV_LP_EVENT_INT;
        hev->xType = HvLpEvent_Type_VirtualIo;
        hev->xSubtype = viomajorsubtype_chario | viochardata;
        hev->xSourceLp = HvLpConfig_getLpIndex();
        hev->xTargetLp = lp;
        hev->xSizeMinus1 = sizeof(struct viocharlpevent);
        hev->xSourceInstanceId = viopath_sourceinst(lp);
        hev->xTargetInstanceId = viopath_targetinst(lp);
}

/*
 * early console device write
 */
static void viocons_write_early(struct console *co, const char *s, unsigned count)
{
        hvlogOutput(s, count);
}

/*
 * console device write
 */
static void viocons_write(struct console *co, const char *s, unsigned count)
{
        int index;
        int begin;
        struct port_info *pi;

        static const char cr = '\r';

        /*
         * Check port data first because the target LP might be valid but
         * simply not active, in which case we want to hvlog the output.
         */
        pi = get_port_data(NULL);
        if (pi == NULL) {
                hvlog("\n\rviocons_write: unable to get port data.");
                return;
        }

        hvlogOutput(s, count);

        if (!viopath_isactive(pi->lp))
                return;

        /* 
         * Any newline character found will cause a
         * carriage return character to be emitted as well. 
         */
        begin = 0;
        for (index = 0; index < count; index++) {
                if (s[index] == '\n') {
                        /* 
                         * Newline found. Print everything up to and 
                         * including the newline
                         */
                        internal_write(pi, &s[begin], index - begin + 1);
                        begin = index + 1;
                        /* Emit a carriage return as well */
                        internal_write(pi, &cr, 1);
                }
        }

        /* If any characters left to write, write them now */
        if ((index - begin) > 0)
                internal_write(pi, &s[begin], index - begin);
}

/*
 * Work out the device associate with this console
 */
static struct tty_driver *viocons_device(struct console *c, int *index)
{
        *index = c->index;
        return viotty_driver;
}

/*
 * console device I/O methods
 */
static struct console viocons_early = {
        .name = "viocons",
        .write = viocons_write_early,
        .flags = CON_PRINTBUFFER,
        .index = -1,
};

static struct console viocons = {
        .name = "viocons",
        .write = viocons_write,
        .device = viocons_device,
        .flags = CON_PRINTBUFFER,
        .index = -1,
};

/*
 * TTY Open method
 */
static int viotty_open(struct tty_struct *tty, struct file *filp)
{
        int port;
        unsigned long flags;
        struct port_info *pi;

        port = tty->index;

        if ((port < 0) || (port >= VTTY_PORTS))
                return -ENODEV;

        spin_lock_irqsave(&consolelock, flags);

        pi = &port_info[port];
        /* If some other TTY is already connected here, reject the open */
        if ((pi->tty) && (pi->tty != tty)) {
                spin_unlock_irqrestore(&consolelock, flags);
                printk(VIOCONS_KERN_WARN
                       "attempt to open device twice from different ttys\n");
                return -EBUSY;
        }
        tty->driver_data = pi;
        pi->tty = tty;
        spin_unlock_irqrestore(&consolelock, flags);

        return 0;
}

/*
 * TTY Close method
 */
static void viotty_close(struct tty_struct *tty, struct file *filp)
{
        unsigned long flags;
        struct port_info *pi;

        spin_lock_irqsave(&consolelock, flags);
        pi = (struct port_info *)tty->driver_data;

        if (!pi || viotty_paranoia_check(pi, tty->name, "viotty_close")) {
                spin_unlock_irqrestore(&consolelock, flags);
                return;
        }
        if (tty->count == 1)
                pi->tty = NULL;
        spin_unlock_irqrestore(&consolelock, flags);
}

/*
 * TTY Write method
 */
static int viotty_write(struct tty_struct *tty, const unsigned char *buf,
                int count)
{
        struct port_info *pi;

        pi = get_port_data(tty);
        if (pi == NULL) {
                hvlog("\n\rviotty_write: no port data.");
                return -ENODEV;
        }

        if (viochar_is_console(pi))
                hvlogOutput(buf, count);

        /*
         * If the path to this LP is closed, don't bother doing anything more.
         * just dump the data on the floor and return count.  For some reason
         * some user level programs will attempt to probe available tty's and
         * they'll attempt a viotty_write on an invalid port which maps to an
         * invalid target lp.  If this is the case then ignore the
         * viotty_write call and, since the viopath isn't active to this
         * partition, return count.
         */
        if (!viopath_isactive(pi->lp))
                return count;

        return internal_write(pi, buf, count);
}

/*
 * TTY put_char method
 */
static void viotty_put_char(struct tty_struct *tty, unsigned char ch)
{
        struct port_info *pi;

        pi = get_port_data(tty);
        if (pi == NULL)
                return;

        /* This will append '\r' as well if the char is '\n' */
        if (viochar_is_console(pi))
                hvlogOutput(&ch, 1);

        if (viopath_isactive(pi->lp))
                internal_write(pi, &ch, 1);
}

/*
 * TTY write_room method
 */
static int viotty_write_room(struct tty_struct *tty)
{
        int i;
        int room = 0;
        struct port_info *pi;
        unsigned long flags;

        spin_lock_irqsave(&consolelock, flags);
        pi = (struct port_info *)tty->driver_data;
        if (!pi || viotty_paranoia_check(pi, tty->name, "viotty_write_room")) {
                spin_unlock_irqrestore(&consolelock, flags);
                return 0;
        }

        /* If no buffers are used, return the max size. */
        if (pi->used == 0) {
                spin_unlock_irqrestore(&consolelock, flags);
                return VIOCHAR_MAX_DATA * VIOCHAR_NUM_BUF;
        }

        /*
         * We retain the spinlock because we want to get an accurate
         * count and it can change on us between each operation if we
         * don't hold the spinlock.
         */
        for (i = 0; ((i < VIOCHAR_NUM_BUF) && (room < VIOCHAR_MAX_DATA)); i++)
                room += (VIOCHAR_MAX_DATA - pi->bufferBytes[i]);
        spin_unlock_irqrestore(&consolelock, flags);

        if (room > VIOCHAR_MAX_DATA)
                room = VIOCHAR_MAX_DATA;
        return room;
}

/*
 * TTY chars_in_buffer method
 */
static int viotty_chars_in_buffer(struct tty_struct *tty)
{
        return 0;
}

static int viotty_ioctl(struct tty_struct *tty, struct file *file,
                        unsigned int cmd, unsigned long arg)
{
        switch (cmd) {
        /*
         * the ioctls below read/set the flags usually shown in the leds
         * don't use them - they will go away without warning
         */
        case KDGETLED:
        case KDGKBLED:
                return put_user(0, (char *)arg);

        case KDSKBLED:
                return 0;
        }

        return n_tty_ioctl(tty, file, cmd, arg);
}

/*
 * Handle an open charLpEvent.  Could be either interrupt or ack
 */
static void vioHandleOpenEvent(struct HvLpEvent *event)
{
        unsigned long flags;
        struct viocharlpevent *cevent = (struct viocharlpevent *)event;
        u8 port = cevent->virtual_device;
        struct port_info *pi;
        int reject = 0;

        if (hvlpevent_is_ack(event)) {
                if (port >= VTTY_PORTS)
                        return;

                spin_lock_irqsave(&consolelock, flags);
                /* Got the lock, don't cause console output */

                pi = &port_info[port];
                if (event->xRc == HvLpEvent_Rc_Good) {
                        pi->seq = pi->ack = 0;
                        /*
                         * This line allows connections from the primary
                         * partition but once one is connected from the
                         * primary partition nothing short of a reboot
                         * of linux will allow access from the hosting
                         * partition again without a required iSeries fix.
                         */
                        pi->lp = event->xTargetLp;
                }

                spin_unlock_irqrestore(&consolelock, flags);
                if (event->xRc != HvLpEvent_Rc_Good)
                        printk(VIOCONS_KERN_WARN
                               "handle_open_event: event->xRc == (%d).\n",
                               event->xRc);

                if (event->xCorrelationToken != 0) {
                        atomic_t *aptr= (atomic_t *)event->xCorrelationToken;
                        atomic_set(aptr, 1);
                } else
                        printk(VIOCONS_KERN_WARN
                               "weird...got open ack without atomic\n");
                return;
        }

        /* This had better require an ack, otherwise complain */
        if (!hvlpevent_need_ack(event)) {
                printk(VIOCONS_KERN_WARN "viocharopen without ack bit!\n");
                return;
        }

        spin_lock_irqsave(&consolelock, flags);
        /* Got the lock, don't cause console output */

        /* Make sure this is a good virtual tty */
        if (port >= VTTY_PORTS) {
                event->xRc = HvLpEvent_Rc_SubtypeError;
                cevent->subtype_result_code = viorc_openRejected;
                /*
                 * Flag state here since we can't printk while holding
                 * a spinlock.
                 */
                reject = 1;
        } else {
                pi = &port_info[port];
                if ((pi->lp != HvLpIndexInvalid) &&
                                (pi->lp != event->xSourceLp)) {
                        /*
                         * If this is tty is already connected to a different
                         * partition, fail.
                         */
                        event->xRc = HvLpEvent_Rc_SubtypeError;
                        cevent->subtype_result_code = viorc_openRejected;
                        reject = 2;
                } else {
                        pi->lp = event->xSourceLp;
                        event->xRc = HvLpEvent_Rc_Good;
                        cevent->subtype_result_code = viorc_good;
                        pi->seq = pi->ack = 0;
                        reject = 0;
                }
        }

        spin_unlock_irqrestore(&consolelock, flags);

        if (reject == 1)
                printk(VIOCONS_KERN_WARN "open rejected: bad virtual tty.\n");
        else if (reject == 2)
                printk(VIOCONS_KERN_WARN
                        "open rejected: console in exclusive use by another partition.\n");

        /* Return the acknowledgement */
        HvCallEvent_ackLpEvent(event);
}

/*
 * Handle a close charLpEvent.  This should ONLY be an Interrupt because the
 * virtual console should never actually issue a close event to the hypervisor
 * because the virtual console never goes away.  A close event coming from the
 * hypervisor simply means that there are no client consoles connected to the
 * virtual console.
 *
 * Regardless of the number of connections masqueraded on the other side of
 * the hypervisor ONLY ONE close event should be called to accompany the ONE
 * open event that is called.  The close event should ONLY be called when NO
 * MORE connections (masqueraded or not) exist on the other side of the
 * hypervisor.
 */
static void vioHandleCloseEvent(struct HvLpEvent *event)
{
        unsigned long flags;
        struct viocharlpevent *cevent = (struct viocharlpevent *)event;
        u8 port = cevent->virtual_device;

        if (hvlpevent_is_int(event)) {
                if (port >= VTTY_PORTS) {
                        printk(VIOCONS_KERN_WARN
                                        "close message from invalid virtual device.\n");
                        return;
                }

                /* For closes, just mark the console partition invalid */
                spin_lock_irqsave(&consolelock, flags);
                /* Got the lock, don't cause console output */

                if (port_info[port].lp == event->xSourceLp)
                        port_info[port].lp = HvLpIndexInvalid;

                spin_unlock_irqrestore(&consolelock, flags);
                printk(VIOCONS_KERN_INFO "close from %d\n", event->xSourceLp);
        } else
                printk(VIOCONS_KERN_WARN
                                "got unexpected close acknowlegement\n");
}

/*
 * Handle a config charLpEvent.  Could be either interrupt or ack
 */
static void vioHandleConfig(struct HvLpEvent *event)
{
        struct viocharlpevent *cevent = (struct viocharlpevent *)event;

        HvCall_writeLogBuffer(cevent->data, cevent->len);

        if (cevent->data[0] == 0x01)
                printk(VIOCONS_KERN_INFO "window resized to %d: %d: %d: %d\n",
                       cevent->data[1], cevent->data[2],
                       cevent->data[3], cevent->data[4]);
        else
                printk(VIOCONS_KERN_WARN "unknown config event\n");
}

/*
 * Handle a data charLpEvent. 
 */
static void vioHandleData(struct HvLpEvent *event)
{
        struct tty_struct *tty;
        unsigned long flags;
        struct viocharlpevent *cevent = (struct viocharlpevent *)event;
        struct port_info *pi;
        int index;
        int num_pushed;
        u8 port = cevent->virtual_device;

        if (port >= VTTY_PORTS) {
                printk(VIOCONS_KERN_WARN "data on invalid virtual device %d\n",
                                port);
                return;
        }

        /*
         * Hold the spinlock so that we don't take an interrupt that
         * changes tty between the time we fetch the port_info
         * pointer and the time we paranoia check.
         */
        spin_lock_irqsave(&consolelock, flags);
        pi = &port_info[port];

        /*
         * Change 05/01/2003 - Ryan Arnold: If a partition other than
         * the current exclusive partition tries to send us data
         * events then just drop them on the floor because we don't
         * want his stinking data.  He isn't authorized to receive
         * data because he wasn't the first one to get the console,
         * therefore he shouldn't be allowed to send data either.
         * This will work without an iSeries fix.
         */
        if (pi->lp != event->xSourceLp) {
                spin_unlock_irqrestore(&consolelock, flags);
                return;
        }

        tty = pi->tty;
        if (tty == NULL) {
                spin_unlock_irqrestore(&consolelock, flags);
                printk(VIOCONS_KERN_WARN "no tty for virtual device %d\n",
                                port);
                return;
        }

        if (tty->magic != TTY_MAGIC) {
                spin_unlock_irqrestore(&consolelock, flags);
                printk(VIOCONS_KERN_WARN "tty bad magic\n");
                return;
        }

        /*
         * Just to be paranoid, make sure the tty points back to this port
         */
        pi = (struct port_info *)tty->driver_data;
        if (!pi || viotty_paranoia_check(pi, tty->name, "vioHandleData")) {
                spin_unlock_irqrestore(&consolelock, flags);
                return;
        }
        spin_unlock_irqrestore(&consolelock, flags);

        /*
         * Change 07/21/2003 - Ryan Arnold: functionality added to
         * support sysrq utilizing ^O as the sysrq key.  The sysrq
         * functionality will only work if built into the kernel and
         * then only if sysrq is enabled through the proc filesystem.
         */
        num_pushed = 0;
        for (index = 0; index < cevent->len; index++) {
                /*
                 * Will be optimized away if !CONFIG_MAGIC_SYSRQ:
                 */
                if (sysrq_on()) {
                        /* 0x0f is the ascii character for ^O */
                        if (cevent->data[index] == '\x0f') {
                                vio_sysrq_pressed = 1;
                                /*
                                 * continue because we don't want to add
                                 * the sysrq key into the data string.
                                 */
                                continue;
                        } else if (vio_sysrq_pressed) {
                                handle_sysrq(cevent->data[index], tty);
                                vio_sysrq_pressed = 0;
                                /*
                                 * continue because we don't want to add
                                 * the sysrq sequence into the data string.
                                 */
                                continue;
                        }
                }
                /*
                 * The sysrq sequence isn't included in this check if
                 * sysrq is enabled and compiled into the kernel because
                 * the sequence will never get inserted into the buffer.
                 * Don't attempt to copy more data into the buffer than we
                 * have room for because it would fail without indication.
                 */
                if(tty_insert_flip_char(tty, cevent->data[index], TTY_NORMAL) == 0) {
                        printk(VIOCONS_KERN_WARN "input buffer overflow!\n");
                        break;
                }
                num_pushed++;
        }

        if (num_pushed)
                tty_flip_buffer_push(tty);
}

/*
 * Handle an ack charLpEvent. 
 */
static void vioHandleAck(struct HvLpEvent *event)
{
        struct viocharlpevent *cevent = (struct viocharlpevent *)event;
        unsigned long flags;
        u8 port = cevent->virtual_device;

        if (port >= VTTY_PORTS) {
                printk(VIOCONS_KERN_WARN "data on invalid virtual device\n");
                return;
        }

        spin_lock_irqsave(&consolelock, flags);
        port_info[port].ack = event->xCorrelationToken;
        spin_unlock_irqrestore(&consolelock, flags);

        if (port_info[port].used)
                send_buffers(&port_info[port]);
}

/*
 * Handle charLpEvents and route to the appropriate routine
 */
static void vioHandleCharEvent(struct HvLpEvent *event)
{
        int charminor;

        if (event == NULL)
                return;

        charminor = event->xSubtype & VIOMINOR_SUBTYPE_MASK;
        switch (charminor) {
        case viocharopen:
                vioHandleOpenEvent(event);
                break;
        case viocharclose:
                vioHandleCloseEvent(event);
                break;
        case viochardata:
                vioHandleData(event);
                break;
        case viocharack:
                vioHandleAck(event);
                break;
        case viocharconfig:
                vioHandleConfig(event);
                break;
        default:
                if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
                        event->xRc = HvLpEvent_Rc_InvalidSubtype;
                        HvCallEvent_ackLpEvent(event);
                }
        }
}

/*
 * Send an open event
 */
static int send_open(HvLpIndex remoteLp, void *sem)
{
        return HvCallEvent_signalLpEventFast(remoteLp,
                        HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_chario | viocharopen,
                        HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
                        viopath_sourceinst(remoteLp),
                        viopath_targetinst(remoteLp),
                        (u64)(unsigned long)sem, VIOVERSION << 16,
                        0, 0, 0, 0);
}

static const struct tty_operations serial_ops = {
        .open = viotty_open,
        .close = viotty_close,
        .write = viotty_write,
        .put_char = viotty_put_char,
        .write_room = viotty_write_room,
        .chars_in_buffer = viotty_chars_in_buffer,
        .ioctl = viotty_ioctl,
};

static int __init viocons_init2(void)
{
        atomic_t wait_flag;
        int rc;

        if (!firmware_has_feature(FW_FEATURE_ISERIES))
                return -ENODEV;

        /* +2 for fudge */
        rc = viopath_open(HvLpConfig_getPrimaryLpIndex(),
                        viomajorsubtype_chario, VIOCHAR_WINDOW + 2);
        if (rc)
                printk(VIOCONS_KERN_WARN "error opening to primary %d\n", rc);

        if (viopath_hostLp == HvLpIndexInvalid)
                vio_set_hostlp();

        /*
         * And if the primary is not the same as the hosting LP, open to the 
         * hosting lp
         */
        if ((viopath_hostLp != HvLpIndexInvalid) &&
            (viopath_hostLp != HvLpConfig_getPrimaryLpIndex())) {
                printk(VIOCONS_KERN_INFO "open path to hosting (%d)\n",
                                viopath_hostLp);
                rc = viopath_open(viopath_hostLp, viomajorsubtype_chario,
                                VIOCHAR_WINDOW + 2);    /* +2 for fudge */
                if (rc)
                        printk(VIOCONS_KERN_WARN
                                "error opening to partition %d: %d\n",
                                viopath_hostLp, rc);
        }

        if (vio_setHandler(viomajorsubtype_chario, vioHandleCharEvent) < 0)
                printk(VIOCONS_KERN_WARN
                                "error seting handler for console events!\n");

        /*
         * First, try to open the console to the hosting lp.
         * Wait on a semaphore for the response.
         */
        atomic_set(&wait_flag, 0);
        if ((viopath_isactive(viopath_hostLp)) &&
            (send_open(viopath_hostLp, (void *)&wait_flag) == 0)) {
                printk(VIOCONS_KERN_INFO "hosting partition %d\n",
                        viopath_hostLp);
                while (atomic_read(&wait_flag) == 0)
                        mb();
                atomic_set(&wait_flag, 0);
        }

        /*
         * If we don't have an active console, try the primary
         */
        if ((!viopath_isactive(port_info[0].lp)) &&
            (viopath_isactive(HvLpConfig_getPrimaryLpIndex())) &&
            (send_open(HvLpConfig_getPrimaryLpIndex(), (void *)&wait_flag)
             == 0)) {
                printk(VIOCONS_KERN_INFO "opening console to primary partition\n");
                while (atomic_read(&wait_flag) == 0)
                        mb();
        }

        /* Initialize the tty_driver structure */
        viotty_driver = alloc_tty_driver(VTTY_PORTS);
        viotty_driver->owner = THIS_MODULE;
        viotty_driver->driver_name = "vioconsole";
        viotty_driver->name = "tty";
        viotty_driver->name_base = 1;
        viotty_driver->major = TTY_MAJOR;
        viotty_driver->minor_start = 1;
        viotty_driver->type = TTY_DRIVER_TYPE_CONSOLE;
        viotty_driver->subtype = 1;
        viotty_driver->init_termios = tty_std_termios;
        viotty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
        tty_set_operations(viotty_driver, &serial_ops);

        if (tty_register_driver(viotty_driver)) {
                printk(VIOCONS_KERN_WARN "couldn't register console driver\n");
                put_tty_driver(viotty_driver);
                viotty_driver = NULL;
        }

        unregister_console(&viocons_early);
        register_console(&viocons);

        return 0;
}

static int __init viocons_init(void)
{
        int i;

        if (!firmware_has_feature(FW_FEATURE_ISERIES))
                return -ENODEV;

        printk(VIOCONS_KERN_INFO "registering console\n");
        for (i = 0; i < VTTY_PORTS; i++) {
                port_info[i].lp = HvLpIndexInvalid;
                port_info[i].magic = VIOTTY_MAGIC;
        }
        HvCall_setLogBufferFormatAndCodepage(HvCall_LogBuffer_ASCII, 437);
        add_preferred_console("viocons", 0, NULL);
        register_console(&viocons_early);
        return 0;
}

console_initcall(viocons_init);
module_init(viocons_init2);