[PATCH] ppc64: iSeries virtual console

From: Stephen Rothwell <sfr@canb.auug.org.au>

This is a forward port of a 2.4 driver that has been present in a couple of
(enterprise) distributions for some time.  It works for me :-), I even get
console output :-) This makes the machine almost usable - next we will get
virtual disk.

It has been considerably tidied up, but if you have any further worries
with it, let me know.

drivers/char/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_SH_SCI)		+= sh-sci.o generic_serial.o
 obj-$(CONFIG_HVC_CONSOLE)	+= hvc_console.o
 obj-$(CONFIG_RAW_DRIVER)	+= raw.o
 obj-$(CONFIG_SGI_L1_SERIAL)	+= sn_serial.o
+obj-$(CONFIG_VIOCONS) += viocons.o
 
 obj-$(CONFIG_PRINTER) += lp.o
 obj-$(CONFIG_TIPAR) += tipar.o

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 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/config.h>
+#include <linux/version.h>
+#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/iSeries/vio.h>
+
+#include <asm/iSeries/HvLpEvent.h>
+#include <asm/iSeries/HvCallEvent.h>
+#include <asm/iSeries/HvLpConfig.h>
+#include <asm/iSeries/HvCall.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 VIOTTY_SERIAL_START 65
+
+static spinlock_t consolelock = SPIN_LOCK_UNLOCKED;
+static spinlock_t consoleloglock = SPIN_LOCK_UNLOCKED;
+
+#ifdef CONFIG_MAGIC_SYSRQ
+static int vio_sysrq_pressed;
+extern int sysrq_enabled;
+#endif
+
+/*
+ * The structure of the events that flow between us and OS/400.  You can't
+ * mess with this unless the OS/400 side changes too
+ */
+struct viocharlpevent {
+	struct HvLpEvent event;
+	u32 reserved;
+	u16 version;
+	u16 subtype_result_code;
+	u8 virtual_device;
+	u8 len;
+	u8 data[VIOCHAR_MAX_DATA];
+};
+
+/*
+ * This is a place where we handle the distribution of memory
+ * for copy_from_user() calls.  The buffer_available array is to
+ * help us determine which buffer to use.
+ */
+#define VIOCHAR_NUM_CFU_BUFFERS	7
+static struct viocharlpevent viocons_cfu_buffer[VIOCHAR_NUM_CFU_BUFFERS];
+static atomic_t viocons_cfu_buffer_available[VIOCHAR_NUM_CFU_BUFFERS];
+
+#define VIOCHAR_WINDOW		10
+#define VIOCHAR_HIGHWATERMARK	3
+
+enum viocharsubtype {
+	viocharopen = 0x0001,
+	viocharclose = 0x0002,
+	viochardata = 0x0003,
+	viocharack = 0x0004,
+	viocharconfig = 0x0005
+};
+
+enum viochar_rc {
+	viochar_rc_ebusy = 1
+};
+
+#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 struct tty_driver *viottyS_driver;
+
+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 = vsnprintf(buf, sizeof(buf) - 1, fmt, args);
+	va_end(args);
+	buf[i++] = '\r';
+	HvCall_writeLogBuffer(buf, i);
+	spin_unlock_irqrestore(&consoleloglock, flags);
+}
+
+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 = KERN_WARNING_VIO
+		"Warning: bad address for port_info struct (%s) in %s\n";
+	static const char *badmagic = KERN_WARNING_VIO
+		"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;
+}
+
+/*
+ * This function should ONLY be called once from viocons_init2
+ */
+static void viocons_init_cfu_buffer(void)
+{
+	int i;
+
+	for (i = 1; i < VIOCHAR_NUM_CFU_BUFFERS; i++)
+		atomic_set(&viocons_cfu_buffer_available[i], 1);
+}
+
+static struct viocharlpevent *viocons_get_cfu_buffer(void)
+{
+	int i;
+
+	/*
+	 * Grab the first available buffer.  It doesn't matter if we
+	 * are interrupted during this array traversal as long as we
+	 * get an available space.
+	 */
+	for (i = 0; i < VIOCHAR_NUM_CFU_BUFFERS; i++)
+		if (atomic_dec_if_positive(&viocons_cfu_buffer_available[i])
+				== 0 )
+			return &viocons_cfu_buffer[i];
+	hvlog("\n\rviocons: viocons_get_cfu_buffer : no free buffers found");
+	return NULL;
+}
+
+static void viocons_free_cfu_buffer(struct viocharlpevent *buffer)
+{
+	int i;
+
+	i = buffer - &viocons_cfu_buffer[0];
+	if (i >= (sizeof(viocons_cfu_buffer) / sizeof(viocons_cfu_buffer[0]))) {
+		hvlog("\n\rviocons: viocons_free_cfu_buffer : buffer pointer not found in list.");
+		return;
+	}
+	if (atomic_read(&viocons_cfu_buffer_available[i]) != 0) {
+		hvlog("\n\rviocons: WARNING : returning unallocated cfu buffer.");
+		return;
+	}
+	atomic_set(&viocons_cfu_buffer_available[i], 1);
+}
+
+/*
+ * 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(KERN_WARNING_VIO
+			       "console 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) {
+			if ((pi->tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
+			    (pi->tty->ldisc.write_wakeup))
+				(pi->tty->ldisc.write_wakeup)(pi->tty);
+			wake_up_interruptible(&pi->tty->write_wait);
+		}
+	}
+
+	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, struct viocharlpevent *viochar)
+{
+	HvLpEvent_Rc hvrc;
+	size_t bleft;
+	size_t curlen;
+	const char *curbuf;
+	unsigned long flags;
+	int copy_needed = (viochar == NULL);
+
+	/*
+	 * 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);
+
+	/*
+	 * If the internal_write() was passed a pointer to a
+	 * viocharlpevent then we don't need to allocate a new one
+	 * (this is the case where we are internal_writing user space
+	 * data).  If we aren't writing user space data then we need
+	 * to get an event from viopath.
+	 */
+	if (copy_needed) {
+		/* This one is fetched from the viopath data structure */
+		viochar = (struct viocharlpevent *)
+			vio_get_event_buffer(viomajorsubtype_chario);
+		/* Make sure we got a buffer */
+		if (viochar == NULL) {
+			spin_unlock_irqrestore(&consolelock, flags);
+			hvlog("\n\rviocons: Can't get viochar 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++;
+
+		if (copy_needed) {
+			memcpy(viochar->data, curbuf, curlen);
+			viochar->len = curlen;
+		}
+
+		viochar->event.xSizeMinus1 =
+		    offsetof(struct viocharlpevent, data) + curlen;
+
+		hvrc = HvCallEvent_signalLpEvent(&viochar->event);
+		if (hvrc) {
+			spin_unlock_irqrestore(&consolelock, flags);
+			if (copy_needed)
+				vio_free_event_buffer(viomajorsubtype_chario, viochar);
+
+			hvlog("viocons: error sending event! %d\n", (int)hvrc);
+			return len - bleft;
+		}
+
+		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);
+	/*
+	 * Since we grabbed it from the viopath data structure, return
+	 * it to the data structure.
+	 */
+	if (copy_needed)
+		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)
+{
+	memset(viochar, 0, sizeof(struct viocharlpevent));
+
+	viochar->event.xFlags.xValid = 1;
+	viochar->event.xFlags.xFunction = HvLpEvent_Function_Int;
+	viochar->event.xFlags.xAckInd = HvLpEvent_AckInd_NoAck;
+	viochar->event.xFlags.xAckType = HvLpEvent_AckType_DeferredAck;
+	viochar->event.xType = HvLpEvent_Type_VirtualIo;
+	viochar->event.xSubtype = viomajorsubtype_chario | viochardata;
+	viochar->event.xSourceLp = HvLpConfig_getLpIndex();
+	viochar->event.xTargetLp = lp;
+	viochar->event.xSizeMinus1 = sizeof(struct viocharlpevent);
+	viochar->event.xSourceInstanceId = viopath_sourceinst(lp);
+	viochar->event.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)) {
+		/*
+		 * This is a VERY noisy trace message in the case where the
+		 * path manager is not active or in the case where this
+		 * function is called prior to viocons initialization.  It is
+		 * being commented out for the sake of a clear trace buffer.
+		 */
+#if 0
+		 hvlog("\n\rviocons_write: path not active to lp %d", pi->lp);
+#endif
+		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,
+					NULL);
+			begin = index + 1;
+			/* Emit a carriage return as well */
+			internal_write(pi, &cr, 1, NULL);
+		}
+	}
+
+	/* If any characters left to write, write them now */
+	if ((index - begin) > 0)
+		internal_write(pi, &s[begin], index - begin, NULL);
+}
+
+/*
+ * 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 = "ttyS",
+	.write = viocons_write_early,
+	.flags = CON_PRINTBUFFER,
+	.index = -1,
+};
+
+static struct console viocons = {
+	.name = "ttyS",
+	.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 >= VIOTTY_SERIAL_START)
+		port -= VIOTTY_SERIAL_START;
+
+	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(KERN_WARNING_VIO
+		       "console 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, int from_user,
+			const unsigned char *buf, int count)
+{
+	int ret;
+	int total = 0;
+	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)) {
+		/* Noisy trace.  Commented unless needed. */
+#if 0
+		 hvlog("\n\rviotty_write: viopath NOT active for lp %d.",pi->lp);
+#endif
+		return count;
+	}
+
+	/*
+	 * If the viotty_write is invoked from user space we want to do the
+	 * copy_from_user() into an event buffer from the cfu buffer before
+	 * internal_write() is called because internal_write may need to buffer
+	 * data which will need to grab a spin_lock and we shouldn't
+	 * copy_from_user() while holding a spin_lock.  Should internal_write()
+	 * not need to buffer data then it'll just use the event we created here
+	 * rather than checking one out from vio_get_event_buffer().
+	 */
+	if (from_user) {
+		struct viocharlpevent *viochar;
+		int curlen;
+		const char *curbuf = buf;
+
+		viochar = viocons_get_cfu_buffer();
+		if (viochar == NULL)
+			return -EAGAIN;
+		initDataEvent(viochar, pi->lp);
+		while (count > 0) {
+			if (count > VIOCHAR_MAX_DATA)
+				curlen = VIOCHAR_MAX_DATA;
+			else
+				curlen = count;
+			viochar->len = curlen;
+			ret = copy_from_user(viochar->data, curbuf, curlen);
+			if (ret)
+				break;
+			ret = internal_write(pi, viochar->data,
+					viochar->len, viochar);
+			total += ret;
+			if (ret != curlen)
+				break;
+			count -= curlen;
+			curbuf += curlen;
+		}
+		viocons_free_cfu_buffer(viochar);
+	} else
+		total = internal_write(pi, buf, count, NULL);
+	return total;
+}
+
+/*
+ * 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, NULL);
+}
+
+/*
+ * TTY flush_chars method
+ */
+static void viotty_flush_chars(struct tty_struct *tty)
+{
+}
+
+/*
+ * 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_room method
+ */
+static int viotty_chars_in_buffer(struct tty_struct *tty)
+{
+	return 0;
+}
+
+static void viotty_flush_buffer(struct tty_struct *tty)
+{
+}
+
+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);
+}
+
+static void viotty_throttle(struct tty_struct *tty)
+{
+}
+
+static void viotty_unthrottle(struct tty_struct *tty)
+{
+}
+
+static void viotty_set_termios(struct tty_struct *tty,
+		struct termios *old_termios)
+{
+}
+
+static void viotty_stop(struct tty_struct *tty)
+{
+}
+
+static void viotty_start(struct tty_struct *tty)
+{
+}
+
+static void viotty_hangup(struct tty_struct *tty)
+{
+}
+
+static void viotty_break(struct tty_struct *tty, int break_state)
+{
+}
+
+static void viotty_send_xchar(struct tty_struct *tty, char ch)
+{
+}
+
+static void viotty_wait_until_sent(struct tty_struct *tty, int timeout)
+{
+}
+
+/*
+ * 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 (event->xFlags.xFunction == HvLpEvent_Function_Ack) {
+		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(KERN_WARNING_VIO
+			       "viocons: event->xRc != HvLpEvent_Rc_Good, event->xRc == (%d).\n",
+			       event->xRc);
+
+		if (event->xCorrelationToken != 0) {
+			atomic_t *aptr= (atomic_t *)event->xCorrelationToken;
+			atomic_set(aptr, 1);
+		} else
+			printk(KERN_WARNING_VIO
+			       "viocons: wierd...got open ack without atomic\n");
+		return;
+	}
+
+	/* This had better require an ack, otherwise complain */
+	if (event->xFlags.xAckInd != HvLpEvent_AckInd_DoAck) {
+		printk(KERN_WARNING_VIO
+		       "console: 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(KERN_WARNING_VIO
+			"viocons: console open rejected : bad virtual tty.\n");
+	else if (reject == 2)
+		printk(KERN_WARNING_VIO
+			"viocons: console 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 (event->xFlags.xFunction == HvLpEvent_Function_Int) {
+		if (port >= VTTY_PORTS) {
+			printk(KERN_WARNING_VIO "viocons: 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(KERN_INFO_VIO
+		       "console close from %d\n", event->xSourceLp);
+	} else
+		printk(KERN_WARNING_VIO
+		       "console 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(KERN_INFO_VIO
+		       "console window resized to %d: %d: %d: %d\n",
+		       cevent->data[1], cevent->data[2],
+		       cevent->data[3], cevent->data[4]);
+	else
+		printk(KERN_WARNING_VIO "console 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;
+	u8 port = cevent->virtual_device;
+
+	if (port >= VTTY_PORTS) {
+		printk(KERN_WARNING_VIO
+		       "console 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(KERN_WARNING_VIO "no tty for virtual device %d\n", port);
+		return;
+	}
+
+	if (tty->magic != TTY_MAGIC) {
+		spin_unlock_irqrestore(&consolelock, flags);
+		printk(KERN_WARNING_VIO "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.
+	 */
+	for (index = 0; index < cevent->len; index++) {
+#ifdef CONFIG_MAGIC_SYSRQ
+		if (sysrq_enabled) {
+			/* 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], NULL, tty);
+				vio_sysrq_pressed = 0;
+				/*
+				 * continue because we don't want to add
+				 * the sysrq sequence into the data string.
+				 */
+				continue;
+			}
+		}
+#endif
+		/*
+		 * 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->flip.count + 1) > TTY_FLIPBUF_SIZE) {
+			printk(KERN_WARNING_VIO
+					"console input buffer overflow!\n");
+			break;
+		}
+		tty_insert_flip_char(tty, cevent->data[index], TTY_NORMAL);
+	}
+
+	/* if cevent->len == 0 then no data was added to the buffer and flip.count == 0 */
+	if (tty->flip.count)
+		/* The next call resets flip.count when the data is flushed. */
+		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(KERN_WARNING_VIO
+		       "viocons: 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 ((event->xFlags.xFunction == HvLpEvent_Function_Int) &&
+		    (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck)) {
+			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 struct tty_operations serial_ops = {
+	.open = viotty_open,
+	.close = viotty_close,
+	.write = viotty_write,
+	.put_char = viotty_put_char,
+	.flush_chars = viotty_flush_chars,
+	.write_room = viotty_write_room,
+	.chars_in_buffer = viotty_chars_in_buffer,
+	.flush_buffer = viotty_flush_buffer,
+	.ioctl = viotty_ioctl,
+	.throttle = viotty_throttle,
+	.unthrottle = viotty_unthrottle,
+	.set_termios = viotty_set_termios,
+	.stop = viotty_stop,
+	.start = viotty_start,
+	.hangup = viotty_hangup,
+	.break_ctl = viotty_break,
+	.send_xchar = viotty_send_xchar,
+	.wait_until_sent = viotty_wait_until_sent,
+};
+
+static int __init viocons_init2(void)
+{
+	atomic_t wait_flag;
+	int rc;
+
+	/* Now open to the primary LP */
+	printk(KERN_INFO_VIO "console open path to primary\n");
+	/* +2 for fudge */
+	rc = viopath_open(HvLpConfig_getPrimaryLpIndex(),
+			viomajorsubtype_chario, VIOCHAR_WINDOW + 2);
+	if (rc)
+		printk(KERN_WARNING_VIO "console 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(KERN_INFO_VIO "console open path to hosting (%d)\n",
+				viopath_hostLp);
+		rc = viopath_open(viopath_hostLp, viomajorsubtype_chario,
+				VIOCHAR_WINDOW + 2);	/* +2 for fudge */
+		if (rc)
+			printk(KERN_WARNING_VIO
+				"console error opening to partition %d: %d\n",
+				viopath_hostLp, rc);
+	}
+
+	if (vio_setHandler(viomajorsubtype_chario, vioHandleCharEvent) < 0)
+		printk(KERN_WARNING_VIO
+				"Error seting handler for console events!\n");
+
+	printk(KERN_INFO_VIO "console major number is %d\n", TTY_MAJOR);
+
+	/* 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(KERN_INFO_VIO
+			"opening console to 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(KERN_INFO_VIO "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->devfs_name = "vcs/";
+	viotty_driver->name = "tty";
+	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);
+
+	viottyS_driver = alloc_tty_driver(VTTY_PORTS);
+	viottyS_driver->owner = THIS_MODULE;
+	viottyS_driver->driver_name = "vioconsole";
+	viottyS_driver->devfs_name = "tts/";
+	viottyS_driver->name = "ttyS";
+	viottyS_driver->major = TTY_MAJOR;
+	viottyS_driver->minor_start = VIOTTY_SERIAL_START;
+	viottyS_driver->type = TTY_DRIVER_TYPE_SERIAL;
+	viottyS_driver->subtype = 1;
+	viottyS_driver->init_termios = tty_std_termios;
+	viottyS_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
+	tty_set_operations(viottyS_driver, &serial_ops);
+
+	if (tty_register_driver(viotty_driver)) {
+		printk(KERN_WARNING_VIO "Couldn't register console driver\n");
+		put_tty_driver(viotty_driver);
+		viotty_driver = NULL;
+	}
+
+	if (tty_register_driver(viottyS_driver)) {
+		printk(KERN_WARNING_VIO "Couldn't register console S driver\n");
+		put_tty_driver(viottyS_driver);
+		viottyS_driver = NULL;
+	}
+
+	viocons_init_cfu_buffer();
+
+	unregister_console(&viocons_early);
+	register_console(&viocons);
+
+	return 0;
+}
+
+static int __init viocons_init(void)
+{
+	int i;
+
+	printk(KERN_INFO_VIO "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);
+	register_console(&viocons_early);
+	return 0;
+}
+
+console_initcall(viocons_init);
+module_init(viocons_init2);