NetBSD-5.0.2/sys/arch/xen/xenbus/xenbus_comms.c
/* $NetBSD: xenbus_comms.c,v 1.10 2008/10/29 13:53:15 cegger Exp $ */
/******************************************************************************
* xenbus_comms.c
*
* Low level code to talks to Xen Store: ringbuffer and event channel.
*
* Copyright (C) 2005 Rusty Russell, IBM Corporation
*
* This file may be distributed separately from the Linux kernel, or
* incorporated into other software packages, subject to the following license:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: xenbus_comms.c,v 1.10 2008/10/29 13:53:15 cegger Exp $");
#include <sys/types.h>
#include <sys/null.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <xen/xen.h> /* for xendomain_is_dom0() */
#include <xen/hypervisor.h>
#include <xen/evtchn.h>
#include <xen/xenbus.h>
#include "xenbus_comms.h"
#undef XENDEBUG
#ifdef XENDEBUG
#define XENPRINTF(x) printf x
#else
#define XENPRINTF(x)
#endif
struct xenstore_domain_interface *xenstore_interface;
static int xenbus_irq = 0;
extern int xenstored_ready;
// static DECLARE_WORK(probe_work, xenbus_probe, NULL);
static int wake_waiting(void *);
static int check_indexes(XENSTORE_RING_IDX, XENSTORE_RING_IDX);
static void *get_output_chunk(XENSTORE_RING_IDX, XENSTORE_RING_IDX,
char *, uint32_t *);
static const void *get_input_chunk(XENSTORE_RING_IDX, XENSTORE_RING_IDX,
const char *, uint32_t *);
static inline struct xenstore_domain_interface *
xenstore_domain_interface(void)
{
return xenstore_interface;
}
static int
wake_waiting(void *arg)
{
if (__predict_false(xenstored_ready == 0 && xendomain_is_dom0())) {
xenstored_ready = 1;
wakeup(&xenstored_ready);
}
wakeup(&xenstore_interface);
return 1;
}
static int
check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod)
{
return ((prod - cons) <= XENSTORE_RING_SIZE);
}
static void *
get_output_chunk(XENSTORE_RING_IDX cons,
XENSTORE_RING_IDX prod,
char *buf, uint32_t *len)
{
*len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod);
if ((XENSTORE_RING_SIZE - (prod - cons)) < *len)
*len = XENSTORE_RING_SIZE - (prod - cons);
return buf + MASK_XENSTORE_IDX(prod);
}
static const void *
get_input_chunk(XENSTORE_RING_IDX cons,
XENSTORE_RING_IDX prod,
const char *buf, uint32_t *len)
{
*len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(cons);
if ((prod - cons) < *len)
*len = prod - cons;
return buf + MASK_XENSTORE_IDX(cons);
}
int
xb_write(const void *data, unsigned len)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
XENSTORE_RING_IDX cons, prod;
int s = spltty();
while (len != 0) {
void *dst;
unsigned int avail;
while ((intf->req_prod - intf->req_cons) == XENSTORE_RING_SIZE) {
XENPRINTF(("xb_write tsleep\n"));
tsleep(&xenstore_interface, PRIBIO, "wrst", 0);
XENPRINTF(("xb_write tsleep done\n"));
}
/* Read indexes, then verify. */
cons = intf->req_cons;
prod = intf->req_prod;
x86_lfence();
if (!check_indexes(cons, prod)) {
splx(s);
return EIO;
}
dst = get_output_chunk(cons, prod, intf->req, &avail);
if (avail == 0)
continue;
if (avail > len)
avail = len;
memcpy(dst, data, avail);
data = (const char *)data + avail;
len -= avail;
/* Other side must not see new header until data is there. */
x86_lfence();
intf->req_prod += avail;
x86_lfence();
hypervisor_notify_via_evtchn(xen_start_info.store_evtchn);
}
splx(s);
return 0;
}
int
xb_read(void *data, unsigned len)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
XENSTORE_RING_IDX cons, prod;
int s = spltty();
while (len != 0) {
unsigned int avail;
const char *src;
while (intf->rsp_cons == intf->rsp_prod)
tsleep(&xenstore_interface, PRIBIO, "rdst", 0);
/* Read indexes, then verify. */
cons = intf->rsp_cons;
prod = intf->rsp_prod;
x86_lfence();
if (!check_indexes(cons, prod)) {
XENPRINTF(("xb_read EIO\n"));
splx(s);
return EIO;
}
src = get_input_chunk(cons, prod, intf->rsp, &avail);
if (avail == 0)
continue;
if (avail > len)
avail = len;
/* We must read header before we read data. */
x86_lfence();
memcpy(data, src, avail);
data = (char *)data + avail;
len -= avail;
/* Other side must not see free space until we've copied out */
x86_lfence();
intf->rsp_cons += avail;
x86_lfence();
XENPRINTF(("Finished read of %i bytes (%i to go)\n",
avail, len));
hypervisor_notify_via_evtchn(xen_start_info.store_evtchn);
}
splx(s);
return 0;
}
/* Set up interrupt handler of store event channel. */
int
xb_init_comms(device_t dev)
{
int err;
if (xenbus_irq)
event_remove_handler(xenbus_irq, wake_waiting, NULL);
err = event_set_handler(xen_start_info.store_evtchn, wake_waiting,
NULL, IPL_TTY, "xenbus");
if (err) {
aprint_error_dev(dev, "request irq failed %i\n", err);
return err;
}
xenbus_irq = xen_start_info.store_evtchn;
aprint_verbose_dev(dev, "using event channel %d\n", xenbus_irq);
hypervisor_enable_event(xenbus_irq);
return 0;
}
/*
* Local variables:
* c-file-style: "linux"
* indent-tabs-mode: t
* c-indent-level: 8
* c-basic-offset: 8
* tab-width: 8
* End:
*/