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hvc_console: rework setup to replace irq functions with callbacks

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This patch tries to change hvc_console to not use request_irq/free_irq if
the backend does not use irqs. This allows virtio_console to use hvc_console
without having a linker reference to request_irq/free_irq.

In addition, together with patch 2/3 it improves the performance for virtio
console input. (an earlier version of this patch was tested by Yajin on lguest)

The irq specific code is moved to hvc_irq.c and selected by the drivers that
use irqs (System p, System i, XEN).

I replaced "int irq" with the opaque "int data". The request_irq and
free_irq calls are replaced with notifier_add and notifier_del. I have also
changed the code a bit to call the notifier_add and notifier_del inside the
spinlock area as the callbacks are found via hp->ops.

Changes since last version:
o remove ifdef
o reintroduce "irq_requested" as "notified"
o cleanups, sparse..

I did not move the timer based polling into a separate polling scheme. I
played with several variants, but it seems we need to sleep/schedule in
a thread even for irq based consoles, as there are throttleing and buffer
size constraints.

I also kept hvc_struct defined in hvc_console.h so that hvc_irq.c can access
the irq_requested element.

Feedback is appreciated. virtio_console is currently the only available console
for kvm on s390. I plan to push this change as soon as all affected parties
agree on it. I would love to get test results from System p, Xen etc.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Christian Borntraeger
2008-06-20 15:24:08 +02:00
committed by Rusty Russell
parent 066f4d82a6
commit 611e097d77
8 changed files with 105 additions and 67 deletions
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35
drivers/char/hvc_console.h
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@@ -26,6 +26,7 @@
#ifndef HVC_CONSOLE_H
#define HVC_CONSOLE_H
#include <linux/kref.h>
/*
* This is the max number of console adapters that can/will be found as
@@ -42,24 +43,50 @@
*/
#define HVC_ALLOC_TTY_ADAPTERS 8
struct hvc_struct {
spinlock_t lock;
int index;
struct tty_struct *tty;
unsigned int count;
int do_wakeup;
char *outbuf;
int outbuf_size;
int n_outbuf;
uint32_t vtermno;
struct hv_ops *ops;
int irq_requested;
int data;
struct list_head next;
struct kref kref; /* ref count & hvc_struct lifetime */
};
/* implemented by a low level driver */
struct hv_ops {
int (*get_chars)(uint32_t vtermno, char *buf, int count);
int (*put_chars)(uint32_t vtermno, const char *buf, int count);
};
struct hvc_struct;
/* Callbacks for notification. Called in open and close */
int (*notifier_add)(struct hvc_struct *hp, int irq);
void (*notifier_del)(struct hvc_struct *hp, int irq);
};
/* Register a vterm and a slot index for use as a console (console_init) */
extern int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops);
/* register a vterm for hvc tty operation (module_init or hotplug add) */
extern struct hvc_struct * __devinit hvc_alloc(uint32_t vtermno, int irq,
extern struct hvc_struct * __devinit hvc_alloc(uint32_t vtermno, int data,
struct hv_ops *ops, int outbuf_size);
/* remove a vterm from hvc tty operation (modele_exit or hotplug remove) */
/* remove a vterm from hvc tty operation (module_exit or hotplug remove) */
extern int __devexit hvc_remove(struct hvc_struct *hp);
/* data available */
int hvc_poll(struct hvc_struct *hp);
void hvc_kick(void);
/* default notifier for irq based notification */
extern int notifier_add_irq(struct hvc_struct *hp, int data);
extern void notifier_del_irq(struct hvc_struct *hp, int data);
#if defined(CONFIG_XMON) && defined(CONFIG_SMP)
#include <asm/xmon.h>