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linux-next/drivers/char/hvc_xen.c
Christian Borntraeger 611e097d77 hvc_console: rework setup to replace irq functions with callbacks
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>
2008-07-25 12:06:06 +10:00

213 lines
4.9 KiB
C

/*
* xen console driver interface to hvc_console.c
*
* (c) 2007 Gerd Hoffmann <kraxel@suse.de>
*
* 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) any 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/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/types.h>
#include <asm/xen/hypervisor.h>
#include <xen/page.h>
#include <xen/events.h>
#include <xen/interface/io/console.h>
#include <xen/hvc-console.h>
#include "hvc_console.h"
#define HVC_COOKIE 0x58656e /* "Xen" in hex */
static struct hvc_struct *hvc;
static int xencons_irq;
/* ------------------------------------------------------------------ */
static unsigned long console_pfn = ~0ul;
static inline struct xencons_interface *xencons_interface(void)
{
if (console_pfn == ~0ul)
return mfn_to_virt(xen_start_info->console.domU.mfn);
else
return __va(console_pfn << PAGE_SHIFT);
}
static inline void notify_daemon(void)
{
/* Use evtchn: this is called early, before irq is set up. */
notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
}
static int write_console(uint32_t vtermno, const char *data, int len)
{
struct xencons_interface *intf = xencons_interface();
XENCONS_RING_IDX cons, prod;
int sent = 0;
cons = intf->out_cons;
prod = intf->out_prod;
mb(); /* update queue values before going on */
BUG_ON((prod - cons) > sizeof(intf->out));
while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
wmb(); /* write ring before updating pointer */
intf->out_prod = prod;
notify_daemon();
return sent;
}
static int read_console(uint32_t vtermno, char *buf, int len)
{
struct xencons_interface *intf = xencons_interface();
XENCONS_RING_IDX cons, prod;
int recv = 0;
cons = intf->in_cons;
prod = intf->in_prod;
mb(); /* get pointers before reading ring */
BUG_ON((prod - cons) > sizeof(intf->in));
while (cons != prod && recv < len)
buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
mb(); /* read ring before consuming */
intf->in_cons = cons;
notify_daemon();
return recv;
}
static struct hv_ops hvc_ops = {
.get_chars = read_console,
.put_chars = write_console,
.notifier_add = notifier_add_irq,
.notifier_del = notifier_del_irq,
};
static int __init xen_init(void)
{
struct hvc_struct *hp;
if (!is_running_on_xen() ||
is_initial_xendomain() ||
!xen_start_info->console.domU.evtchn)
return -ENODEV;
xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
if (xencons_irq < 0)
xencons_irq = 0; /* NO_IRQ */
hp = hvc_alloc(HVC_COOKIE, xencons_irq, &hvc_ops, 256);
if (IS_ERR(hp))
return PTR_ERR(hp);
hvc = hp;
console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
return 0;
}
void xen_console_resume(void)
{
if (xencons_irq)
rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
}
static void __exit xen_fini(void)
{
if (hvc)
hvc_remove(hvc);
}
static int xen_cons_init(void)
{
if (!is_running_on_xen())
return 0;
hvc_instantiate(HVC_COOKIE, 0, &hvc_ops);
return 0;
}
module_init(xen_init);
module_exit(xen_fini);
console_initcall(xen_cons_init);
static void raw_console_write(const char *str, int len)
{
while(len > 0) {
int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
if (rc <= 0)
break;
str += rc;
len -= rc;
}
}
#ifdef CONFIG_EARLY_PRINTK
static void xenboot_write_console(struct console *console, const char *string,
unsigned len)
{
unsigned int linelen, off = 0;
const char *pos;
raw_console_write(string, len);
write_console(0, "(early) ", 8);
while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
linelen = pos-string+off;
if (off + linelen > len)
break;
write_console(0, string+off, linelen);
write_console(0, "\r\n", 2);
off += linelen + 1;
}
if (off < len)
write_console(0, string+off, len-off);
}
struct console xenboot_console = {
.name = "xenboot",
.write = xenboot_write_console,
.flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
};
#endif /* CONFIG_EARLY_PRINTK */
void xen_raw_console_write(const char *str)
{
raw_console_write(str, strlen(str));
}
void xen_raw_printk(const char *fmt, ...)
{
static char buf[512];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
xen_raw_console_write(buf);
}