freebsd-dev/sys/xen/evtchn/evtchn_dev.c
2010-02-21 01:12:18 +00:00

393 lines
8.0 KiB
C

/******************************************************************************
* evtchn.c
*
* Xenolinux driver for receiving and demuxing event-channel signals.
*
* Copyright (c) 2004, K A Fraser
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/bus.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/selinfo.h>
#include <sys/poll.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/ioccom.h>
#include <machine/xen/xen-os.h>
#include <xen/xen_intr.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <machine/resource.h>
#include <machine/xen/synch_bitops.h>
#include <xen/hypervisor.h>
#include <xen/evtchn.h>
typedef struct evtchn_sotfc {
struct selinfo ev_rsel;
} evtchn_softc_t;
#ifdef linuxcrap
/* NB. This must be shared amongst drivers if more things go in /dev/xen */
static devfs_handle_t xen_dev_dir;
#endif
/* Only one process may open /dev/xen/evtchn at any time. */
static unsigned long evtchn_dev_inuse;
/* Notification ring, accessed via /dev/xen/evtchn. */
#define EVTCHN_RING_SIZE 2048 /* 2048 16-bit entries */
#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
static uint16_t *ring;
static unsigned int ring_cons, ring_prod, ring_overflow;
/* Which ports is user-space bound to? */
static uint32_t bound_ports[32];
/* Unique address for processes to sleep on */
static void *evtchn_waddr = &ring;
static struct mtx lock, upcall_lock;
static d_read_t evtchn_read;
static d_write_t evtchn_write;
static d_ioctl_t evtchn_ioctl;
static d_poll_t evtchn_poll;
static d_open_t evtchn_open;
static d_close_t evtchn_close;
void
evtchn_device_upcall(int port)
{
mtx_lock(&upcall_lock);
mask_evtchn(port);
clear_evtchn(port);
if ( ring != NULL ) {
if ( (ring_prod - ring_cons) < EVTCHN_RING_SIZE ) {
ring[EVTCHN_RING_MASK(ring_prod)] = (uint16_t)port;
if ( ring_cons == ring_prod++ ) {
wakeup(evtchn_waddr);
}
}
else {
ring_overflow = 1;
}
}
mtx_unlock(&upcall_lock);
}
static void
__evtchn_reset_buffer_ring(void)
{
/* Initialise the ring to empty. Clear errors. */
ring_cons = ring_prod = ring_overflow = 0;
}
static int
evtchn_read(struct cdev *dev, struct uio *uio, int ioflag)
{
int rc;
unsigned int count, c, p, sst = 0, bytes1 = 0, bytes2 = 0;
count = uio->uio_resid;
count &= ~1; /* even number of bytes */
if ( count == 0 )
{
rc = 0;
goto out;
}
if ( count > PAGE_SIZE )
count = PAGE_SIZE;
for ( ; ; ) {
if ( (c = ring_cons) != (p = ring_prod) )
break;
if ( ring_overflow ) {
rc = EFBIG;
goto out;
}
if (sst != 0) {
rc = EINTR;
goto out;
}
/* PCATCH == check for signals before and after sleeping
* PWAIT == priority of waiting on resource
*/
sst = tsleep(evtchn_waddr, PWAIT|PCATCH, "evchwt", 10);
}
/* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
if ( ((c ^ p) & EVTCHN_RING_SIZE) != 0 ) {
bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * sizeof(uint16_t);
bytes2 = EVTCHN_RING_MASK(p) * sizeof(uint16_t);
}
else {
bytes1 = (p - c) * sizeof(uint16_t);
bytes2 = 0;
}
/* Truncate chunks according to caller's maximum byte count. */
if ( bytes1 > count ) {
bytes1 = count;
bytes2 = 0;
}
else if ( (bytes1 + bytes2) > count ) {
bytes2 = count - bytes1;
}
if ( uiomove(&ring[EVTCHN_RING_MASK(c)], bytes1, uio) ||
((bytes2 != 0) && uiomove(&ring[0], bytes2, uio)))
/* keeping this around as its replacement is not equivalent
* copyout(&ring[0], &buf[bytes1], bytes2)
*/
{
rc = EFAULT;
goto out;
}
ring_cons += (bytes1 + bytes2) / sizeof(uint16_t);
rc = bytes1 + bytes2;
out:
return rc;
}
static int
evtchn_write(struct cdev *dev, struct uio *uio, int ioflag)
{
int rc, i, count;
count = uio->uio_resid;
uint16_t *kbuf = (uint16_t *)malloc(PAGE_SIZE, M_DEVBUF, M_WAITOK);
if ( kbuf == NULL )
return ENOMEM;
count &= ~1; /* even number of bytes */
if ( count == 0 ) {
rc = 0;
goto out;
}
if ( count > PAGE_SIZE )
count = PAGE_SIZE;
if ( uiomove(kbuf, count, uio) != 0 ) {
rc = EFAULT;
goto out;
}
mtx_lock_spin(&lock);
for ( i = 0; i < (count/2); i++ )
if ( test_bit(kbuf[i], &bound_ports[0]) )
unmask_evtchn(kbuf[i]);
mtx_unlock_spin(&lock);
rc = count;
out:
free(kbuf, M_DEVBUF);
return rc;
}
static int
evtchn_ioctl(struct cdev *dev, unsigned long cmd, caddr_t arg,
int mode, struct thread *td __unused)
{
int rc = 0;
mtx_lock_spin(&lock);
switch ( cmd )
{
case EVTCHN_RESET:
__evtchn_reset_buffer_ring();
break;
case EVTCHN_BIND:
if ( !synch_test_and_set_bit((uintptr_t)arg, &bound_ports[0]) )
unmask_evtchn((uintptr_t)arg);
else
rc = EINVAL;
break;
case EVTCHN_UNBIND:
if ( synch_test_and_clear_bit((uintptr_t)arg, &bound_ports[0]) )
mask_evtchn((uintptr_t)arg);
else
rc = EINVAL;
break;
default:
rc = ENOSYS;
break;
}
mtx_unlock_spin(&lock);
return rc;
}
static int
evtchn_poll(struct cdev *dev, int poll_events, struct thread *td)
{
evtchn_softc_t *sc;
unsigned int mask = POLLOUT | POLLWRNORM;
sc = dev->si_drv1;
if ( ring_cons != ring_prod )
mask |= POLLIN | POLLRDNORM;
else if ( ring_overflow )
mask = POLLERR;
else
selrecord(td, &sc->ev_rsel);
return mask;
}
static int
evtchn_open(struct cdev *dev, int flag, int otyp, struct thread *td)
{
uint16_t *_ring;
if (flag & O_NONBLOCK)
return EBUSY;
if ( synch_test_and_set_bit(0, &evtchn_dev_inuse) )
return EBUSY;
if ( (_ring = (uint16_t *)malloc(PAGE_SIZE, M_DEVBUF, M_WAITOK)) == NULL )
return ENOMEM;
mtx_lock_spin(&lock);
ring = _ring;
__evtchn_reset_buffer_ring();
mtx_unlock_spin(&lock);
return 0;
}
static int
evtchn_close(struct cdev *dev, int flag, int otyp, struct thread *td __unused)
{
int i;
if (ring != NULL) {
free(ring, M_DEVBUF);
ring = NULL;
}
mtx_lock_spin(&lock);
for ( i = 0; i < NR_EVENT_CHANNELS; i++ )
if ( synch_test_and_clear_bit(i, &bound_ports[0]) )
mask_evtchn(i);
mtx_unlock_spin(&lock);
evtchn_dev_inuse = 0;
return 0;
}
static struct cdevsw evtchn_devsw = {
d_version: D_VERSION,
d_open: evtchn_open,
d_close: evtchn_close,
d_read: evtchn_read,
d_write: evtchn_write,
d_ioctl: evtchn_ioctl,
d_poll: evtchn_poll,
d_name: "evtchn",
d_flags: 0,
};
/* XXX - if this device is ever supposed to support use by more than one process
* this global static will have to go away
*/
static struct cdev *evtchn_dev;
static int
evtchn_dev_init(void *dummy __unused)
{
/* XXX I believe we don't need these leaving them here for now until we
* have some semblance of it working
*/
mtx_init(&upcall_lock, "evtchup", NULL, MTX_DEF);
/* (DEVFS) create '/dev/misc/evtchn'. */
evtchn_dev = make_dev(&evtchn_devsw, 0, UID_ROOT, GID_WHEEL, 0600, "xen/evtchn");
mtx_init(&lock, "evch", NULL, MTX_SPIN | MTX_NOWITNESS);
evtchn_dev->si_drv1 = malloc(sizeof(evtchn_softc_t), M_DEVBUF, M_WAITOK);
bzero(evtchn_dev->si_drv1, sizeof(evtchn_softc_t));
/* XXX I don't think we need any of this rubbish */
#if 0
if ( err != 0 )
{
printk(KERN_ALERT "Could not register /dev/misc/evtchn\n");
return err;
}
/* (DEVFS) create directory '/dev/xen'. */
xen_dev_dir = devfs_mk_dir(NULL, "xen", NULL);
/* (DEVFS) &link_dest[pos] == '../misc/evtchn'. */
pos = devfs_generate_path(evtchn_miscdev.devfs_handle,
&link_dest[3],
sizeof(link_dest) - 3);
if ( pos >= 0 )
strncpy(&link_dest[pos], "../", 3);
/* (DEVFS) symlink '/dev/xen/evtchn' -> '../misc/evtchn'. */
(void)devfs_mk_symlink(xen_dev_dir,
"evtchn",
DEVFS_FL_DEFAULT,
&link_dest[pos],
&symlink_handle,
NULL);
/* (DEVFS) automatically destroy the symlink with its destination. */
devfs_auto_unregister(evtchn_miscdev.devfs_handle, symlink_handle);
#endif
if (bootverbose)
printf("Event-channel device installed.\n");
return 0;
}
SYSINIT(evtchn_dev_init, SI_SUB_DRIVERS, SI_ORDER_FIRST, evtchn_dev_init, NULL);