linux/drivers/media/dvb-core/dvb_ringbuffer.c
Sakari Ailus bcb63314e2 [media] media: Drop FSF's postal address from the source code files
Drop the FSF's postal address from the source code files that typically
contain mostly the license text. Of the 628 removed instances, 578 are
outdated.

The patch has been created with the following command without manual edits:

git grep -l "675 Mass Ave\|59 Temple Place\|51 Franklin St" -- \
	drivers/media/ include/media|while read i; do i=$i perl -e '
open(F,"< $ENV{i}");
$a=join("", <F>);
$a =~ s/[ \t]*\*\n.*You should.*\n.*along with.*\n.*(\n.*USA.*$)?\n//m
	&& $a =~ s/(^.*)Or, (point your browser to) /$1To obtain the license, $2\n$1/m;
close(F);
open(F, "> $ENV{i}");
print F $a;
close(F);'; done

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
2017-01-27 11:38:09 -02:00

370 lines
9.9 KiB
C

/*
*
* dvb_ringbuffer.c: ring buffer implementation for the dvb driver
*
* Copyright (C) 2003 Oliver Endriss
* Copyright (C) 2004 Andrew de Quincey
*
* based on code originally found in av7110.c & dvb_ci.c:
* Copyright (C) 1999-2003 Ralph Metzler
* & Marcus Metzler for convergence integrated media GmbH
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* 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 Lesser General Public License for more details.
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include "dvb_ringbuffer.h"
#define PKT_READY 0
#define PKT_DISPOSED 1
void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
{
rbuf->pread=rbuf->pwrite=0;
rbuf->data=data;
rbuf->size=len;
rbuf->error=0;
init_waitqueue_head(&rbuf->queue);
spin_lock_init(&(rbuf->lock));
}
int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
{
/* smp_load_acquire() to load write pointer on reader side
* this pairs with smp_store_release() in dvb_ringbuffer_write(),
* dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset()
*
* for memory barriers also see Documentation/circular-buffers.txt
*/
return (rbuf->pread == smp_load_acquire(&rbuf->pwrite));
}
ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
{
ssize_t free;
/* ACCESS_ONCE() to load read pointer on writer side
* this pairs with smp_store_release() in dvb_ringbuffer_read(),
* dvb_ringbuffer_read_user(), dvb_ringbuffer_flush(),
* or dvb_ringbuffer_reset()
*/
free = ACCESS_ONCE(rbuf->pread) - rbuf->pwrite;
if (free <= 0)
free += rbuf->size;
return free-1;
}
ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
{
ssize_t avail;
/* smp_load_acquire() to load write pointer on reader side
* this pairs with smp_store_release() in dvb_ringbuffer_write(),
* dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset()
*/
avail = smp_load_acquire(&rbuf->pwrite) - rbuf->pread;
if (avail < 0)
avail += rbuf->size;
return avail;
}
void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
{
/* dvb_ringbuffer_flush() counts as read operation
* smp_load_acquire() to load write pointer
* smp_store_release() to update read pointer, this ensures that the
* correct pointer is visible for subsequent dvb_ringbuffer_free()
* calls on other cpu cores
*/
smp_store_release(&rbuf->pread, smp_load_acquire(&rbuf->pwrite));
rbuf->error = 0;
}
EXPORT_SYMBOL(dvb_ringbuffer_flush);
void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf)
{
/* dvb_ringbuffer_reset() counts as read and write operation
* smp_store_release() to update read pointer
*/
smp_store_release(&rbuf->pread, 0);
/* smp_store_release() to update write pointer */
smp_store_release(&rbuf->pwrite, 0);
rbuf->error = 0;
}
void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
{
unsigned long flags;
spin_lock_irqsave(&rbuf->lock, flags);
dvb_ringbuffer_flush(rbuf);
spin_unlock_irqrestore(&rbuf->lock, flags);
wake_up(&rbuf->queue);
}
ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len)
{
size_t todo = len;
size_t split;
split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
if (split > 0) {
if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
return -EFAULT;
buf += split;
todo -= split;
/* smp_store_release() for read pointer update to ensure
* that buf is not overwritten until read is complete,
* this pairs with ACCESS_ONCE() in dvb_ringbuffer_free()
*/
smp_store_release(&rbuf->pread, 0);
}
if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
return -EFAULT;
/* smp_store_release() to update read pointer, see above */
smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size);
return len;
}
void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len)
{
size_t todo = len;
size_t split;
split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
if (split > 0) {
memcpy(buf, rbuf->data+rbuf->pread, split);
buf += split;
todo -= split;
/* smp_store_release() for read pointer update to ensure
* that buf is not overwritten until read is complete,
* this pairs with ACCESS_ONCE() in dvb_ringbuffer_free()
*/
smp_store_release(&rbuf->pread, 0);
}
memcpy(buf, rbuf->data+rbuf->pread, todo);
/* smp_store_release() to update read pointer, see above */
smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size);
}
ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
{
size_t todo = len;
size_t split;
split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
if (split > 0) {
memcpy(rbuf->data+rbuf->pwrite, buf, split);
buf += split;
todo -= split;
/* smp_store_release() for write pointer update to ensure that
* written data is visible on other cpu cores before the pointer
* update, this pairs with smp_load_acquire() in
* dvb_ringbuffer_empty() or dvb_ringbuffer_avail()
*/
smp_store_release(&rbuf->pwrite, 0);
}
memcpy(rbuf->data+rbuf->pwrite, buf, todo);
/* smp_store_release() for write pointer update, see above */
smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size);
return len;
}
ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
const u8 __user *buf, size_t len)
{
int status;
size_t todo = len;
size_t split;
split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
if (split > 0) {
status = copy_from_user(rbuf->data+rbuf->pwrite, buf, split);
if (status)
return len - todo;
buf += split;
todo -= split;
/* smp_store_release() for write pointer update to ensure that
* written data is visible on other cpu cores before the pointer
* update, this pairs with smp_load_acquire() in
* dvb_ringbuffer_empty() or dvb_ringbuffer_avail()
*/
smp_store_release(&rbuf->pwrite, 0);
}
status = copy_from_user(rbuf->data+rbuf->pwrite, buf, todo);
if (status)
return len - todo;
/* smp_store_release() for write pointer update, see above */
smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size);
return len;
}
ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
{
int status;
ssize_t oldpwrite = rbuf->pwrite;
DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
status = dvb_ringbuffer_write(rbuf, buf, len);
if (status < 0) rbuf->pwrite = oldpwrite;
return status;
}
ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
int offset, u8 __user *buf, size_t len)
{
size_t todo;
size_t split;
size_t pktlen;
pktlen = rbuf->data[idx] << 8;
pktlen |= rbuf->data[(idx + 1) % rbuf->size];
if (offset > pktlen) return -EINVAL;
if ((offset + len) > pktlen) len = pktlen - offset;
idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
todo = len;
split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
if (split > 0) {
if (copy_to_user(buf, rbuf->data+idx, split))
return -EFAULT;
buf += split;
todo -= split;
idx = 0;
}
if (copy_to_user(buf, rbuf->data+idx, todo))
return -EFAULT;
return len;
}
ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
int offset, u8* buf, size_t len)
{
size_t todo;
size_t split;
size_t pktlen;
pktlen = rbuf->data[idx] << 8;
pktlen |= rbuf->data[(idx + 1) % rbuf->size];
if (offset > pktlen) return -EINVAL;
if ((offset + len) > pktlen) len = pktlen - offset;
idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
todo = len;
split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
if (split > 0) {
memcpy(buf, rbuf->data+idx, split);
buf += split;
todo -= split;
idx = 0;
}
memcpy(buf, rbuf->data+idx, todo);
return len;
}
void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
{
size_t pktlen;
rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
// clean up disposed packets
while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
} else {
// first packet is not disposed, so we stop cleaning now
break;
}
}
}
ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
{
int consumed;
int curpktlen;
int curpktstatus;
if (idx == -1) {
idx = rbuf->pread;
} else {
curpktlen = rbuf->data[idx] << 8;
curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
}
consumed = (idx - rbuf->pread) % rbuf->size;
while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
curpktlen = rbuf->data[idx] << 8;
curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
if (curpktstatus == PKT_READY) {
*pktlen = curpktlen;
return idx;
}
consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
}
// no packets available
return -1;
}
EXPORT_SYMBOL(dvb_ringbuffer_init);
EXPORT_SYMBOL(dvb_ringbuffer_empty);
EXPORT_SYMBOL(dvb_ringbuffer_free);
EXPORT_SYMBOL(dvb_ringbuffer_avail);
EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
EXPORT_SYMBOL(dvb_ringbuffer_read_user);
EXPORT_SYMBOL(dvb_ringbuffer_read);
EXPORT_SYMBOL(dvb_ringbuffer_write);
EXPORT_SYMBOL(dvb_ringbuffer_write_user);