[PATCH] interrupt driven hvc_console as vio device (final)

Ryan Arnold
2004-08-27T22:42:07Z

[-- Attachment #1: Type: text/plain, Size: 2890 bytes --]

Whoops, forgot the patch! OK lets try this again, here is the patch!

Changelog:

This is an hvc_console patch which provides driver and ppc64
architecture fixes to enable the hvc_console driver to register itself
as a vio device with the vio bus, provide hotplug add/remove for vty
adapters, and act as an interrupt driven driver on Power-5 hardware or
remain as a polling driver on Power-4 hardware.

arch/ppc64/kernel/hvconsole.c
-----------------------------------------------------------------------
-Changed hvc_get_chars() and hvc_put_chars() api to take vtermno rather
than index number.

-Added hvc_find_vtys() function which walks the bus looking for
vterm/vty devices to callback to the hvc_console driver. This provides
console output functionality prior to early console init (pre mem init
and pre device probe).

include/asm-ppc64/hvconsole.h
-----------------------------------------------------------------------

-Changed hvc_get_chars() and hvc_put_chars() api to take vtermno rather
than index number.

-Added hvc_find_vtys() function.

-Added hvc_instantiate() function which is implemented by a console
driver wanting to receive a callback of and early console init.

drivers/char/hvc_console.c
-----------------------------------------------------------------------

-Switch khvcd from kernel_threads to kthreads which got rid of
deprecated daemonize().

-Added module exit clause to be thorough (not terribly necessary with a
console driver of course)

-Added early discovery of vterm/vty adapters by doing a bus walk on
early console init which results in hvc_instantiate() callback and
addition of the vtermno into a static array of vtermnos supported as
console adapters (meaning the console api's work against these vtermnos
prior to full console initialization).

-This driver is now registered as a vio driver which means that vty
adapters are now managed via probe/remove. This means hvc_console
supports hotplug vty adapters.

-Driver now requests more device nodes than what was found on the
initial bus walk when registered as a tty driver to make room for
hotplug vty adapters. These secondary vty adapters provide a tty tunnel
between partitions.

-Removed static hvc_struct array and replaced with a linux list that has
elements (hvc_struct instances) added/removed on probe/remove AFTER
early console init. This is important because kmalloc can't be done at
early console init.

-Driver now either runs in interrupt driven mode or in polling mode on
older hardware. The khvcd is smart enough to not 'schedule()' when
there are no interrupts.

-kobjects are now used for ref counting on the hvc_struct instances.

-This driver puts the tty layer to sleep on hvc_close() if there are
pending data writes being blocked by firmware.

-Removed useless spinlocks in hvc_chars_in_buffer() and hvc_write_room.

Ryan S. Arnold
IBM Linux Technology Center

[-- Attachment #2: interrupt-driven_hvc_console_draft3.patch --]
[-- Type: text/x-patch, Size: 28847 bytes --]

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ryan S. Arnold <rsa@us.ibm.com>
--- linux-2.6.8.1/include/asm-ppc64/hvconsole.h Sat Aug 14 05:55:33 2004
+++ hvc_console_linux-2.6.8.1/include/asm-ppc64/hvconsole.h Thu Aug 19 11:12:58 2004
@@ -22,9 +22,19 @@
#ifndef _PPC64_HVCONSOLE_H
#define _PPC64_HVCONSOLE_H

-extern int hvc_get_chars(int index, char *buf, int count);
-extern int hvc_put_chars(int index, const char *buf, int count);
-extern int hvc_count(int *start_termno);
+/*
+ * This is the max number of console adapters that can/will be found as
+ * console devices on first stage console init. Any number beyond this range
+ * can't be used as a console device but is still a valid tty device.
+ */
+#define MAX_NR_HVC_CONSOLES 16

-#endif /* _PPC64_HVCONSOLE_H */
+extern int hvc_get_chars(uint32_t vtermno, char *buf, int count);
+extern int hvc_put_chars(uint32_t vtermno, const char *buf, int count);
+
+/* Early discovery of console adapters. */
+extern int hvc_find_vtys(void);

+/* Implemented by a console driver */
+extern int hvc_instantiate(uint32_t vtermno, int index);
+#endif /* _PPC64_HVCONSOLE_H */
--- linux-2.6.8.1/arch/ppc64/kernel/hvconsole.c Sat Aug 14 05:55:32 2004
+++ hvc_console_linux-2.6.8.1/arch/ppc64/kernel/hvconsole.c Thu Aug 26 10:37:28 2004
@@ -1,6 +1,10 @@
/*
* hvconsole.c
* Copyright (C) 2004 Hollis Blanchard, IBM Corporation
+ * Copyright (C) 2004 IBM Corporation
+ *
+ * Additional Author(s):
+ * Ryan S. Arnold <rsa@us.ibm.com>
*
* LPAR console support.
*
@@ -22,14 +26,22 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/hvcall.h>
-#include <asm/prom.h>
#include <asm/hvconsole.h>
+#include <asm/prom.h>

-int hvc_get_chars(int index, char *buf, int count)
+/**
+ * hvc_get_chars - retrieve characters from firmware for denoted vterm adatper
+ * @vtermno: The vtermno or unit_address of the adapter from which to fetch the
+ * data.
+ * @buf: The character buffer into which to put the character data fetched from
+ * firmware.
+ * @count: not used?
+ */
+int hvc_get_chars(uint32_t vtermno, char *buf, int count)
{
unsigned long got;

- if (plpar_hcall(H_GET_TERM_CHAR, index, 0, 0, 0, &got,
+ if (plpar_hcall(H_GET_TERM_CHAR, vtermno, 0, 0, 0, &got,
(unsigned long *)buf, (unsigned long *)buf+1) == H_Success) {
/*
* Work around a HV bug where it gives us a null
@@ -53,40 +65,56 @@

EXPORT_SYMBOL(hvc_get_chars);

-int hvc_put_chars(int index, const char *buf, int count)
+/**
+ * hvc_put_chars: send characters to firmware for denoted vterm adapter
+ * @vtermno: The vtermno or unit_address of the adapter from which the data
+ * originated.
+ * @buf: The character buffer that contains the character data to send to
+ * firmware.
+ * @count: Send this number of characters.
+ */
+int hvc_put_chars(uint32_t vtermno, const char *buf, int count)
{
unsigned long *lbuf = (unsigned long *) buf;
long ret;

- ret = plpar_hcall_norets(H_PUT_TERM_CHAR, index, count, lbuf[0],
+ ret = plpar_hcall_norets(H_PUT_TERM_CHAR, vtermno, count, lbuf[0],
lbuf[1]);
if (ret == H_Success)
return count;
if (ret == H_Busy)
return 0;
- return -1;
+ return -EIO;
}

EXPORT_SYMBOL(hvc_put_chars);

-/* return the number of client vterms present */
-/* XXX this requires an interface change to handle multiple discontiguous
- * vterms */
-int hvc_count(int *start_termno)
+/*
+ * We hope/assume that the first vty found corresponds to the first console
+ * device.
+ */
+int hvc_find_vtys(void)
{
struct device_node *vty;
int num_found = 0;

- /* consider only the first vty node.
- * we should _always_ be able to find one. */
- vty = of_find_node_by_name(NULL, "vty");
- if (vty && device_is_compatible(vty, "hvterm1")) {
- u32 *termno = (u32 *)get_property(vty, "reg", NULL);
-
- if (termno && start_termno)
- *start_termno = *termno;
- num_found = 1;
- of_node_put(vty);
+ for (vty = of_find_node_by_name(NULL, "vty"); vty != NULL;
+ vty = of_find_node_by_name(vty, "vty")) {
+ uint32_t *vtermno;
+
+ /* We have statically defined space for only a certain number of
+ * console adapters. */
+ if (num_found >= MAX_NR_HVC_CONSOLES)
+ break;
+
+ vtermno = (uint32_t *)get_property(vty, "reg", NULL);
+ if (!vtermno)
+ continue;
+
+ if (device_is_compatible(vty, "hvterm1")) {
+ hvc_instantiate(*vtermno, num_found);
+ ++num_found;
+ }
}

return num_found;
--- linux-2.6.8.1/drivers/char/hvc_console.c Sat Aug 14 05:56:00 2004
+++ hvc_console_linux-2.6.8.1/drivers/char/hvc_console.c Thu Aug 26 09:57:37 2004
@@ -1,6 +1,11 @@
/*
* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
* Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
+ * Copyright (C) 2004 IBM Corporation
+ *
+ * Additional Author(s):
+ * Ryan S. Arnold <rsa@us.ibm.com>
*
* 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
@@ -17,38 +22,51 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

+#include <linux/console.h>
+#include <linux/cpumask.h>
#include <linux/init.h>
+#include <linux/kbd_kern.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/kthread.h>
+#include <linux/list.h>
#include <linux/module.h>
-#include <linux/console.h>
#include <linux/major.h>
-#include <linux/kernel.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/sched.h>
-#include <linux/kbd_kern.h>
-#include <asm/uaccess.h>
#include <linux/spinlock.h>
-#include <linux/cpumask.h>
-
-extern int hvc_count(int *);
-extern int hvc_get_chars(int index, char *buf, int count);
-extern int hvc_put_chars(int index, const char *buf, int count);
+#include <asm/uaccess.h>
+#include <asm/hvconsole.h>
+#include <asm/vio.h>

#define HVC_MAJOR 229
#define HVC_MINOR 0

-#define MAX_NR_HVC_CONSOLES 4
-
#define TIMEOUT ((HZ + 99) / 100)

+/*
+ * Wait this long per iteration while trying to push buffered data to the
+ * hypervisor before allowing the tty to complete a close operation.
+ */
+#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
+
+/*
+ * The Linux TTY code does not support dynamic addition of tty derived devices
+ * so we need to know how many tty devices we might need when space is allocated
+ * for the tty device. Since this driver supports hotplug of vty adapters we
+ * need to make sure we have enough allocated.
+ */
+#define HVC_ALLOC_TTY_ADAPTERS 8
+
static struct tty_driver *hvc_driver;
-static int hvc_offset;
#ifdef CONFIG_MAGIC_SYSRQ
static int sysrq_pressed;
#endif

#define N_OUTBUF 16
+#define N_INBUF 16

#define __ALIGNED__ __attribute__((__aligned__(8)))

@@ -60,59 +78,244 @@
int do_wakeup;
char outbuf[N_OUTBUF] __ALIGNED__;
int n_outbuf;
+ uint32_t vtermno;
+ int irq_requested;
+ int irq;
+ struct list_head next;
+ struct kobject kobj; /* ref count & hvc_struct lifetime */
+ struct vio_dev *vdev;
};

-struct hvc_struct hvc_struct[MAX_NR_HVC_CONSOLES];
+/* dynamic list of hvc_struct instances */
+static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);

-static int hvc_open(struct tty_struct *tty, struct file * filp)
+/*
+ * Protect the list of hvc_struct instances from inserts and removals during
+ * list traversal.
+ */
+static spinlock_t hvc_structs_lock = SPIN_LOCK_UNLOCKED;
+
+/*
+ * Initial console vtermnos for console API usage prior to full console
+ * initialization. Any vty adapter outside this range will not have usable
+ * console interfaces but can still be used as a tty device. This has to be
+ * static because kmalloc will not work during early console init.
+ */
+static uint32_t vtermnos[MAX_NR_HVC_CONSOLES];
+
+/* Used for accounting purposes */
+static int num_vterms = 0;
+
+static struct task_struct *hvc_task;
+
+/*
+ * This value is used to associate a tty->index value to a hvc_struct based
+ * upon order of exposure via hvc_probe().
+ */
+static int hvc_count = -1;
+
+/* Picks up late kicks after list walk but before schedule() */
+static int hvc_kicked;
+
+/* Wake the sleeping khvcd */
+static void hvc_kick(void)
+{
+ hvc_kicked = 1;
+ wake_up_process(hvc_task);
+}
+
+/*
+ * NOTE: This API isn't used if the console adapter doesn't support interrupts.
+ * In this case the console is poll driven.
+ */
+static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
+{
+ hvc_kick();
+ return IRQ_HANDLED;
+}
+
+static void hvc_unthrottle(struct tty_struct *tty)
+{
+ hvc_kick();
+}
+
+/*
+ * Do not call this function with either the hvc_strucst_lock or the hvc_struct
+ * lock held. If successful, this function increments the kobject reference
+ * count against the target hvc_struct so it should be released when finished.
+ */
+struct hvc_struct *hvc_get_by_index(int index)
{
- int line = tty->index;
struct hvc_struct *hp;
unsigned long flags;

- if (line < 0 || line >= MAX_NR_HVC_CONSOLES)
+ spin_lock(&hvc_structs_lock);
+
+ list_for_each_entry(hp, &hvc_structs, next) {
+ spin_lock_irqsave(&hp->lock, flags);
+ if (hp->index == index) {
+ kobject_get(&hp->kobj);
+ spin_unlock_irqrestore(&hp->lock, flags);
+ spin_unlock(&hvc_structs_lock);
+ return hp;
+ }
+ spin_unlock_irqrestore(&hp->lock, flags);
+ }
+ hp = NULL;
+
+ spin_unlock(&hvc_structs_lock);
+ return hp;
+}
+
+/*
+ * The TTY interface won't be used until after the vio layer has exposed the vty
+ * adapter to the kernel.
+ */
+static int hvc_open(struct tty_struct *tty, struct file * filp)
+{
+ struct hvc_struct *hp;
+ unsigned long flags;
+ int irq = NO_IRQ;
+ int rc = 0;
+ struct kobject *kobjp;
+
+ /* Auto increments kobject reference if found. */
+ if (!(hp = hvc_get_by_index(tty->index))) {
+ printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
return -ENODEV;
- hp = &hvc_struct[line];
+ }

- tty->driver_data = hp;
spin_lock_irqsave(&hp->lock, flags);
+ /* Check and then increment for fast path open. */
+ if (hp->count++ > 0) {
+ spin_unlock_irqrestore(&hp->lock, flags);
+ hvc_kick();
+ return 0;
+ } /* else count == 0 */
+
+ tty->driver_data = hp;
hp->tty = tty;
- hp->count++;
+ /* Save for request_irq outside of spin_lock. */
+ irq = hp->irq;
+ if (irq != NO_IRQ)
+ hp->irq_requested = 1;
+
+ kobjp = &hp->kobj;
+
spin_unlock_irqrestore(&hp->lock, flags);
+ /* check error, fallback to non-irq */
+ if (irq != NO_IRQ)
+ rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
+
+ /*
+ * If the request_irq() fails and we return an error. The tty layer
+ * will call hvc_close() after a failed open but we don't want to clean
+ * up there so we'll clean up here and clear out the previously set
+ * tty fields and return the kobject reference.
+ */
+ if (rc) {
+ spin_lock_irqsave(&hp->lock, flags);
+ hp->tty = NULL;
+ hp->irq_requested = 0;
+ spin_unlock_irqrestore(&hp->lock, flags);
+ tty->driver_data = NULL;
+ kobject_put(kobjp);
+ }
+ /* Force wakeup of the polling thread */
+ hvc_kick();

- return 0;
+ return rc;
}

static void hvc_close(struct tty_struct *tty, struct file * filp)
{
- struct hvc_struct *hp = tty->driver_data;
+ struct hvc_struct *hp;
+ struct kobject *kobjp;
+ int irq = NO_IRQ;
unsigned long flags;

if (tty_hung_up_p(filp))
return;
+
+ /*
+ * No driver_data means that this close was issued after a failed
+ * hvcs_open by the tty layer's release_dev() function and we can just
+ * exit cleanly because the kobject reference wasn't made.
+ */
+ if (!tty->driver_data)
+ return;
+
+ hp = tty->driver_data;
spin_lock_irqsave(&hp->lock, flags);
- if (--hp->count == 0)
+
+ kobjp = &hp->kobj;
+ if (--hp->count == 0) {
+ if (hp->irq_requested)
+ irq = hp->irq;
+ hp->irq_requested = 0;
+
+ /* We are done with the tty pointer now. */
hp->tty = NULL;
- else if (hp->count < 0)
- printk(KERN_ERR "hvc_close %lu: oops, count is %d\n",
- hp - hvc_struct, hp->count);
- spin_unlock_irqrestore(&hp->lock, flags);
+ spin_unlock_irqrestore(&hp->lock, flags);
+
+ /*
+ * Chain calls chars_in_buffer() and returns immediately if
+ * there is no buffered data otherwise sleeps on a wait queue
+ * waking periodically to check chars_in_buffer().
+ */
+ tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
+
+ tty->driver_data = NULL;
+
+ if (irq != NO_IRQ)
+ free_irq(irq, hp);
+
+ } else {
+ if (hp->count < 0)
+ printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
+ hp->vtermno, hp->count);
+ spin_unlock_irqrestore(&hp->lock, flags);
+ }
+
+ kobject_put(kobjp);
}

static void hvc_hangup(struct tty_struct *tty)
{
struct hvc_struct *hp = tty->driver_data;
+ unsigned long flags;
+ int irq = NO_IRQ;
+ int temp_open_count;
+ struct kobject *kobjp;

+ spin_lock_irqsave(&hp->lock, flags);
+ kobjp = &hp->kobj;
+ temp_open_count = hp->count;
hp->count = 0;
+ hp->n_outbuf = 0;
hp->tty = NULL;
+ if (hp->irq_requested)
+ /* Saved for use outside of spin_lock. */
+ irq = hp->irq;
+ hp->irq_requested = 0;
+ spin_unlock_irqrestore(&hp->lock, flags);
+ if (irq != NO_IRQ)
+ free_irq(irq, hp);
+ while(temp_open_count) {
+ --temp_open_count;
+ kobject_put(kobjp);
+ }
}

-/* called with hp->lock held */
+/*
+ * Push buffered characters whether they were just recently buffered or waiting
+ * on a blocked hypervisor. Call this function with hp->lock held.
+ */
static void hvc_push(struct hvc_struct *hp)
{
int n;

- n = hvc_put_chars(hp->index + hvc_offset, hp->outbuf, hp->n_outbuf);
+ n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
if (n <= 0) {
if (n == 0)
return;
@@ -127,77 +330,122 @@
hp->do_wakeup = 1;
}

-static int hvc_write(struct tty_struct *tty, int from_user,
- const unsigned char *buf, int count)
+static inline int __hvc_write_user(struct hvc_struct *hp,
+ const unsigned char *buf, int count)
{
- struct hvc_struct *hp = tty->driver_data;
char *tbuf, *p;
int tbsize, rsize, written = 0;
unsigned long flags;

- if (from_user) {
- tbsize = min(count, (int)PAGE_SIZE);
- if (!(tbuf = kmalloc(tbsize, GFP_KERNEL)))
- return -ENOMEM;
-
- while ((rsize = count - written) > 0) {
- int wsize;
- if (rsize > tbsize)
- rsize = tbsize;
-
- p = tbuf;
- rsize -= copy_from_user(p, buf, rsize);
- if (!rsize) {
- if (written == 0)
- written = -EFAULT;
- break;
- }
- buf += rsize;
- written += rsize;
-
- spin_lock_irqsave(&hp->lock, flags);
- for (wsize = N_OUTBUF - hp->n_outbuf; rsize && wsize;
- wsize = N_OUTBUF - hp->n_outbuf) {
- if (wsize > rsize)
- wsize = rsize;
- memcpy(hp->outbuf + hp->n_outbuf, p, wsize);
- hp->n_outbuf += wsize;
- hvc_push(hp);
- rsize -= wsize;
- p += wsize;
- }
- spin_unlock_irqrestore(&hp->lock, flags);
-
- if (rsize)
- break;
+ tbsize = min(count, (int)PAGE_SIZE);
+ if (!(tbuf = kmalloc(tbsize, GFP_KERNEL)))
+ return -ENOMEM;

- if (count < tbsize)
- tbsize = count;
+ while ((rsize = count - written) > 0) {
+ int wsize;
+ if (rsize > tbsize)
+ rsize = tbsize;
+
+ p = tbuf;
+ rsize -= copy_from_user(p, buf, rsize);
+ if (!rsize) {
+ if (written == 0)
+ written = -EFAULT;
+ break;
}
+ buf += rsize;

- kfree(tbuf);
- } else {
spin_lock_irqsave(&hp->lock, flags);
- while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
- if (rsize > count)
- rsize = count;
- memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
- count -= rsize;
- buf += rsize;
- hp->n_outbuf += rsize;
- written += rsize;
+
+ /* Push pending writes: make some room in buffer */
+ if (hp->n_outbuf > 0)
hvc_push(hp);
+
+ for (wsize = N_OUTBUF - hp->n_outbuf; rsize && wsize;
+ wsize = N_OUTBUF - hp->n_outbuf) {
+ if (wsize > rsize)
+ wsize = rsize;
+ memcpy(hp->outbuf + hp->n_outbuf, p, wsize);
+ hp->n_outbuf += wsize;
+ hvc_push(hp);
+ rsize -= wsize;
+ p += wsize;
+ written += wsize;
}
spin_unlock_irqrestore(&hp->lock, flags);
+
+ if (rsize)
+ break;
+
+ if (count < tbsize)
+ tbsize = count;
+ }
+
+ kfree(tbuf);
+
+ return written;
+}
+
+static inline int __hvc_write_kernel(struct hvc_struct *hp,
+ const unsigned char *buf, int count)
+{
+ unsigned long flags;
+ int rsize, written = 0;
+
+ spin_lock_irqsave(&hp->lock, flags);
+
+ /* Push pending writes */
+ if (hp->n_outbuf > 0)
+ hvc_push(hp);
+
+ while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
+ if (rsize > count)
+ rsize = count;
+ memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
+ count -= rsize;
+ buf += rsize;
+ hp->n_outbuf += rsize;
+ written += rsize;
+ hvc_push(hp);
}
+ spin_unlock_irqrestore(&hp->lock, flags);
+
+ return written;
+}
+static int hvc_write(struct tty_struct *tty, int from_user,
+ const unsigned char *buf, int count)
+{
+ struct hvc_struct *hp = tty->driver_data;
+ int written;
+
+ if (from_user)
+ written = __hvc_write_user(hp, buf, count);
+ else
+ written = __hvc_write_kernel(hp, buf, count);
+
+ /*
+ * Racy, but harmless, kick thread if there is still pending data.
+ * There really is nothing wrong with kicking the thread, even if there
+ * is no buffered data.
+ */
+ if (hp->n_outbuf)
+ hvc_kick();

return written;
}

+/*
+ * This is actually a contract between the driver and the tty layer outlining
+ * how much write room the driver can guarentee will be sent OR BUFFERED. This
+ * driver MUST honor the return value.
+ */
static int hvc_write_room(struct tty_struct *tty)
{
struct hvc_struct *hp = tty->driver_data;

+ if (!hp)
+ return -1;
+
return N_OUTBUF - hp->n_outbuf;
}

@@ -205,57 +453,111 @@
{
struct hvc_struct *hp = tty->driver_data;

+ if (!hp)
+ return -1;
return hp->n_outbuf;
}

-static void hvc_poll(int index)
+#define HVC_POLL_READ 0x00000001
+#define HVC_POLL_WRITE 0x00000002
+#define HVC_POLL_QUICK 0x00000004
+
+static int hvc_poll(struct hvc_struct *hp)
{
- struct hvc_struct *hp = &hvc_struct[index];
struct tty_struct *tty;
- int i, n;
- char buf[16] __ALIGNED__;
+ int i, n, poll_mask = 0;
+ char buf[N_INBUF] __ALIGNED__;
unsigned long flags;
+ int read_total = 0;

spin_lock_irqsave(&hp->lock, flags);

+ /* Push pending writes */
if (hp->n_outbuf > 0)
hvc_push(hp);
+ /* Reschedule us if still some write pending */
+ if (hp->n_outbuf > 0)
+ poll_mask |= HVC_POLL_WRITE;

+ /* No tty attached, just skip */
tty = hp->tty;
- if (tty) {
- for (;;) {
- if (TTY_FLIPBUF_SIZE - tty->flip.count < sizeof(buf))
- break;
- n = hvc_get_chars(index + hvc_offset, buf, sizeof(buf));
- if (n <= 0)
- break;
- for (i = 0; i < n; ++i) {
-#ifdef CONFIG_MAGIC_SYSRQ /* Handle the SysRq Hack */
- if (buf[i] == '\x0f') { /* ^O -- should support a sequence */
- sysrq_pressed = 1;
- continue;
- } else if (sysrq_pressed) {
- handle_sysrq(buf[i], NULL, tty);
- sysrq_pressed = 0;
- continue;
- }
-#endif
- tty_insert_flip_char(tty, buf[i], 0);
+ if (tty == NULL)
+ goto bail;
+
+ /* Now check if we can get data (are we throttled ?) */
+ if (test_bit(TTY_THROTTLED, &tty->flags))
+ goto throttled;
+
+ /* If we aren't interrupt driven and aren't throttled, we always
+ * request a reschedule
+ */
+ if (hp->irq == NO_IRQ)
+ poll_mask |= HVC_POLL_READ;
+
+ /* Read data if any */
+ for (;;) {
+ int count = N_INBUF;
+ if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
+ count = TTY_FLIPBUF_SIZE - tty->flip.count;
+
+ /* If flip is full, just reschedule a later read */
+ if (count == 0) {
+ poll_mask |= HVC_POLL_READ;
+ break;
+ }
+
+ n = hvc_get_chars(hp->vtermno, buf, count);
+ if (n <= 0) {
+ /* Hangup the tty when disconnected from host */
+ if (n == -EPIPE) {
+ spin_unlock_irqrestore(&hp->lock, flags);
+ tty_hangup(tty);
+ spin_lock_irqsave(&hp->lock, flags);
+ }
+ break;
+ }
+ for (i = 0; i < n; ++i) {
+#ifdef CONFIG_MAGIC_SYSRQ
+ /* Handle the SysRq Hack */
+ if (buf[i] == '\x0f') { /* ^O -- should support a sequence */
+ sysrq_pressed = 1;
+ continue;
+ } else if (sysrq_pressed) {
+ handle_sysrq(buf[i], NULL, tty);
+ sysrq_pressed = 0;
+ continue;
}
+#endif /* CONFIG_MAGIC_SYSRQ */
+ tty_insert_flip_char(tty, buf[i], 0);
}
+
if (tty->flip.count)
tty_schedule_flip(tty);

- if (hp->do_wakeup) {
- hp->do_wakeup = 0;
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP))
- && tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
- wake_up_interruptible(&tty->write_wait);
+ /*
+ * Account for the total amount read in one loop, and if above
+ * 64 bytes, we do a quick schedule loop to let the tty grok the
+ * data and eventually throttle us.
+ */
+ read_total += n;
+ if (read_total >= 64) {
+ poll_mask |= HVC_POLL_QUICK;
+ break;
}
}
-
+ throttled:
+ /* Wakeup write queue if necessary */
+ if (hp->do_wakeup) {
+ hp->do_wakeup = 0;
+ if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP))
+ && tty->ldisc.write_wakeup)
+ (tty->ldisc.write_wakeup)(tty);
+ wake_up_interruptible(&tty->write_wait);
+ }
+ bail:
spin_unlock_irqrestore(&hp->lock, flags);
+
+ return poll_mask;
}

#if defined(CONFIG_XMON) && defined(CONFIG_SMP)
@@ -264,21 +566,47 @@
static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
#endif

-
+/*
+ * This kthread is either polling or interrupt driven. This is determined by
+ * calling hvc_poll() who determines whether a console adapter support
+ * interrupts.
+ */
int khvcd(void *unused)
{
- int i;
-
- daemonize("khvcd");
+ int poll_mask;
+ struct hvc_struct *hp;

- for (;;) {
+ __set_current_state(TASK_RUNNING);
+ do {
+ poll_mask = 0;
+ hvc_kicked = 0;
+ wmb();
if (cpus_empty(cpus_in_xmon)) {
- for (i = 0; i < MAX_NR_HVC_CONSOLES; ++i)
- hvc_poll(i);
+ spin_lock(&hvc_structs_lock);
+ list_for_each_entry(hp, &hvc_structs, next) {
+ /*hp = list_entry(node, struct hvc_struct, * next); */
+ poll_mask |= hvc_poll(hp);
+ }
+ spin_unlock(&hvc_structs_lock);
+ } else
+ poll_mask |= HVC_POLL_READ;
+ if (hvc_kicked)
+ continue;
+ if (poll_mask & HVC_POLL_QUICK) {
+ yield();
+ continue;
}
set_current_state(TASK_INTERRUPTIBLE);
- schedule_timeout(TIMEOUT);
- }
+ if (!hvc_kicked) {
+ if (poll_mask == 0)
+ schedule();
+ else
+ schedule_timeout(TIMEOUT);
+ }
+ __set_current_state(TASK_RUNNING);
+ } while (!kthread_should_stop());
+
+ return 0;
}

static struct tty_operations hvc_ops = {
@@ -286,19 +614,124 @@
.close = hvc_close,
.write = hvc_write,
.hangup = hvc_hangup,
+ .unthrottle = hvc_unthrottle,
.write_room = hvc_write_room,
.chars_in_buffer = hvc_chars_in_buffer,
};

-int __init hvc_init(void)
+char hvc_driver_name[] = "hvc_console";
+
+static struct vio_device_id hvc_driver_table[] __devinitdata= {
+ {"serial", "hvterm1"},
+ { 0, }
+};
+MODULE_DEVICE_TABLE(vio, hvc_driver_table);
+
+/* callback when the kboject ref count reaches zero. */
+static void destroy_hvc_struct(struct kobject *kobj)
{
- int num = hvc_count(&hvc_offset);
- int i;
+ struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
+ unsigned long flags;

- if (num > MAX_NR_HVC_CONSOLES)
- num = MAX_NR_HVC_CONSOLES;
+ spin_lock(&hvc_structs_lock);

- hvc_driver = alloc_tty_driver(num);
+ spin_lock_irqsave(&hp->lock, flags);
+ list_del(&(hp->next));
+ spin_unlock_irqrestore(&hp->lock, flags);
+
+ spin_unlock(&hvc_structs_lock);
+
+ kfree(hp);
+}
+
+static struct kobj_type hvc_kobj_type = {
+ .release = destroy_hvc_struct,
+};
+
+static int __devinit hvc_probe(
+ struct vio_dev *dev,
+ const struct vio_device_id *id)
+{
+ struct hvc_struct *hp;
+
+ /* probed with invalid parameters. */
+ if (!dev || !id)
+ return -EPERM;
+
+ hp = kmalloc(sizeof(*hp), GFP_KERNEL);
+ if (!hp)
+ return -ENOMEM;
+
+ memset(hp, 0x00, sizeof(*hp));
+ hp->vtermno = dev->unit_address;
+ hp->vdev = dev;
+ hp->vdev->dev.driver_data = hp;
+ hp->irq = dev->irq;
+
+ kobject_init(&hp->kobj);
+ hp->kobj.ktype = &hvc_kobj_type;
+
+ hp->lock = SPIN_LOCK_UNLOCKED;
+ spin_lock(&hvc_structs_lock);
+ hp->index = ++hvc_count;
+ list_add_tail(&(hp->next), &hvc_structs);
+ spin_unlock(&hvc_structs_lock);
+
+ return 0;
+}
+
+static int __devexit hvc_remove(struct vio_dev *dev)
+{
+ struct hvc_struct *hp = dev->dev.driver_data;
+ unsigned long flags;
+ struct kobject *kobjp;
+ struct tty_struct *tty;
+
+ spin_lock_irqsave(&hp->lock, flags);
+ tty = hp->tty;
+ kobjp = &hp->kobj;
+
+ if (hp->index < MAX_NR_HVC_CONSOLES)
+ vtermnos[hp->index] = -1;
+
+ /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
+
+ spin_unlock_irqrestore(&hp->lock, flags);
+
+ /*
+ * We 'put' the instance that was grabbed when the kobject instance
+ * was intialized using kobject_init(). Let the last holder of this
+ * kobject cause it to be removed, which will probably be the tty_hangup
+ * below.
+ */
+ kobject_put(kobjp);
+
+ /*
+ * This function call will auto chain call hvc_hangup. The tty should
+ * always be valid at this time unless a simultaneous tty close already
+ * cleaned up the hvc_struct.
+ */
+ if (tty)
+ tty_hangup(tty);
+ return 0;
+}
+
+static struct vio_driver hvc_vio_driver = {
+ .name = hvc_driver_name,
+ .id_table = hvc_driver_table,
+ .probe = hvc_probe,
+ .remove = hvc_remove,
+};
+
+/* Driver initialization. Follow console initialization. This is where the TTY
+ * interfaces start to become available. */
+int __init hvc_init(void)
+{
+ int rc;
+
+ /* We need more than num_vterms adapters due to hotplug additions. */
+ hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
+ /* hvc_driver = alloc_tty_driver(num_vterms); */
if (!hvc_driver)
return -ENOMEM;

@@ -312,31 +745,73 @@
hvc_driver->init_termios = tty_std_termios;
hvc_driver->flags = TTY_DRIVER_REAL_RAW;
tty_set_operations(hvc_driver, &hvc_ops);
- for (i = 0; i < num; i++) {
- hvc_struct[i].lock = SPIN_LOCK_UNLOCKED;
- hvc_struct[i].index = i;
- }

if (tty_register_driver(hvc_driver))
panic("Couldn't register hvc console driver\n");

- if (num > 0)
- kernel_thread(khvcd, NULL, CLONE_KERNEL);
+ /* Always start the kthread because there can be hotplug vty adapters
+ * added later. */
+ hvc_task = kthread_run(khvcd, NULL, "khvcd");
+ if (IS_ERR(hvc_task)) {
+ panic("Couldn't create kthread for console.\n");
+ put_tty_driver(hvc_driver);
+ return -EIO;
+ }

- return 0;
+ /* Register as a vio device to receive callbacks */
+ rc = vio_register_driver(&hvc_vio_driver);
+
+ return rc;
}

+/* This isn't particularily necessary due to this being a console driver but it
+ * is nice to be thorough */
static void __exit hvc_exit(void)
{
+ kthread_stop(hvc_task);
+
+ vio_unregister_driver(&hvc_vio_driver);
+ tty_unregister_driver(hvc_driver);
+ /* return tty_struct instances allocated in hvc_init(). */
+ put_tty_driver(hvc_driver);
+}
+
+/*
+ * Console APIs, NOT TTY. These APIs are available immediately when
+ * hvc_console_setup() finds adapters.
+ */
+
+/*
+ * hvc_instantiate() is an early console discovery method which locates consoles
+ * prior to the vio subsystem discovering them. Hotplugged vty adapters do NOT
+ * get an hvc_instantiate() callback since the appear after early console init.
+ */
+int hvc_instantiate(uint32_t vtermno, int index)
+{
+ if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
+ return -1;
+
+ if (vtermnos[index] != -1)
+ return -1;
+
+ vtermnos[index] = vtermno;
+ return 0;
}

void hvc_console_print(struct console *co, const char *b, unsigned count)
{
char c[16] __ALIGNED__;
- unsigned i, n;
+ unsigned i, n = 0;
int r, donecr = 0;

- i = n = 0;
+ /* Console access attempt outside of acceptable console range. */
+ if (co->index >= MAX_NR_HVC_CONSOLES)
+ return;
+
+ /* This console adapter was removed so it is not useable. */
+ if (vtermnos[co->index] < 0)
+ return;
+
while (count > 0 || i > 0) {
if (count > 0 && i < sizeof(c)) {
if (b[n] == '\n' && !donecr) {
@@ -348,7 +823,7 @@
--count;
}
} else {
- r = hvc_put_chars(co->index + hvc_offset, c, i);
+ r = hvc_put_chars(vtermnos[co->index], c, i);
if (r < 0) {
/* throw away chars on error */
i = 0;
@@ -369,9 +844,6 @@

static int __init hvc_console_setup(struct console *co, char *options)
{
- if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES
- || co->index >= hvc_count(&hvc_offset))
- return -1;
return 0;
}

@@ -384,8 +856,14 @@
.index = -1,
};

+/* Early console initialization. Preceeds driver initialization. */
static int __init hvc_console_init(void)
{
+ int i;
+
+ for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
+ vtermnos[i] = -1;
+ num_vterms = hvc_find_vtys();
register_console(&hvc_con_driver);
return 0;
}