diff options
Diffstat (limited to 'drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c')
-rw-r--r-- | drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c new file mode 100644 index 000000000000..384acb8d2eae --- /dev/null +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c @@ -0,0 +1,156 @@ +/** + * Copyright (c) 2010-2012 Broadcom. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions, and the following disclaimer, + * without modification. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The names of the above-listed copyright holders may not be used + * to endorse or promote products derived from this software without + * specific prior written permission. + * + * ALTERNATIVELY, this software may be distributed under the terms of the + * GNU General Public License ("GPL") version 2, as published by the Free + * Software Foundation. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS + * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "vchiq_util.h" +#include "vchiq_killable.h" + +static inline int is_pow2(int i) +{ + return i && !(i & (i - 1)); +} + +int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size) +{ + WARN_ON(!is_pow2(size)); + + queue->size = size; + queue->read = 0; + queue->write = 0; + queue->initialized = 1; + + sema_init(&queue->pop, 0); + sema_init(&queue->push, 0); + + queue->storage = kzalloc(size * sizeof(VCHIQ_HEADER_T *), GFP_KERNEL); + if (queue->storage == NULL) { + vchiu_queue_delete(queue); + return 0; + } + return 1; +} + +void vchiu_queue_delete(VCHIU_QUEUE_T *queue) +{ + if (queue->storage != NULL) + kfree(queue->storage); +} + +int vchiu_queue_is_empty(VCHIU_QUEUE_T *queue) +{ + return queue->read == queue->write; +} + +int vchiu_queue_is_full(VCHIU_QUEUE_T *queue) +{ + return queue->write == queue->read + queue->size; +} + +void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) +{ + if (!queue->initialized) + return; + + while (queue->write == queue->read + queue->size) { + if (down_interruptible(&queue->pop) != 0) { + flush_signals(current); + } + } + + /* + * Write to queue->storage must be visible after read from + * queue->read + */ + smp_mb(); + + queue->storage[queue->write & (queue->size - 1)] = header; + + /* + * Write to queue->storage must be visible before write to + * queue->write + */ + smp_wmb(); + + queue->write++; + + up(&queue->push); +} + +VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue) +{ + while (queue->write == queue->read) { + if (down_interruptible(&queue->push) != 0) { + flush_signals(current); + } + } + + up(&queue->push); // We haven't removed anything from the queue. + + /* + * Read from queue->storage must be visible after read from + * queue->write + */ + smp_rmb(); + + return queue->storage[queue->read & (queue->size - 1)]; +} + +VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) +{ + VCHIQ_HEADER_T *header; + + while (queue->write == queue->read) { + if (down_interruptible(&queue->push) != 0) { + flush_signals(current); + } + } + + /* + * Read from queue->storage must be visible after read from + * queue->write + */ + smp_rmb(); + + header = queue->storage[queue->read & (queue->size - 1)]; + + /* + * Read from queue->storage must be visible before write to + * queue->read + */ + smp_mb(); + + queue->read++; + + up(&queue->pop); + + return header; +} |