Implement iio_dma_buffer_attach_dmabuf(), iio_dma_buffer_detach_dmabuf() and iio_dma_buffer_transfer_dmabuf(), which can then be used by the IIO DMA buffer implementations.
Signed-off-by: Paul Cercueil paul@crapouillou.net Signed-off-by: Nuno Sa nuno.sa@analog.com
--- v3: Update code to provide the functions that will be used as callbacks for the new IOCTLs.
v6: - Update iio_dma_buffer_enqueue_dmabuf() to take a dma_fence pointer - Pass that dma_fence pointer along to iio_buffer_signal_dmabuf_done() - Add iio_dma_buffer_lock_queue() / iio_dma_buffer_unlock_queue() - Do not lock the queue in iio_dma_buffer_enqueue_dmabuf(). The caller will ensure that it has been locked already. - Replace "int += bool;" by "if (bool) int++;" - Use dma_fence_begin/end_signalling in the dma_fence critical sections - Use one "num_dmabufs" fields instead of one "num_blocks" and one "num_fileio_blocks". Make it an atomic_t, which makes it possible to decrement it atomically in iio_buffer_block_release() without having to lock the queue mutex; and in turn, it means that we don't need to use iio_buffer_block_put_atomic() everywhere to avoid locking the queue mutex twice. - Use cleanup.h guard(mutex) when possible - Explicitely list all states in the switch in iio_dma_can_enqueue_block() - Rename iio_dma_buffer_fileio_mode() to iio_dma_buffer_can_use_fileio(), and add a comment explaining why it cannot race vs. DMABUF. --- drivers/iio/buffer/industrialio-buffer-dma.c | 181 +++++++++++++++++-- include/linux/iio/buffer-dma.h | 31 ++++ 2 files changed, 201 insertions(+), 11 deletions(-)
diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index 5610ba67925e..c0f539af98f9 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -4,6 +4,8 @@ * Author: Lars-Peter Clausen lars@metafoo.de */
+#include <linux/atomic.h> +#include <linux/cleanup.h> #include <linux/slab.h> #include <linux/kernel.h> #include <linux/module.h> @@ -14,6 +16,8 @@ #include <linux/poll.h> #include <linux/iio/buffer_impl.h> #include <linux/iio/buffer-dma.h> +#include <linux/dma-buf.h> +#include <linux/dma-fence.h> #include <linux/dma-mapping.h> #include <linux/sizes.h>
@@ -94,13 +98,18 @@ static void iio_buffer_block_release(struct kref *kref) { struct iio_dma_buffer_block *block = container_of(kref, struct iio_dma_buffer_block, kref); + struct iio_dma_buffer_queue *queue = block->queue;
- WARN_ON(block->state != IIO_BLOCK_STATE_DEAD); + WARN_ON(block->fileio && block->state != IIO_BLOCK_STATE_DEAD);
- dma_free_coherent(block->queue->dev, PAGE_ALIGN(block->size), - block->vaddr, block->phys_addr); + if (block->fileio) { + dma_free_coherent(queue->dev, PAGE_ALIGN(block->size), + block->vaddr, block->phys_addr); + } else { + atomic_dec(&queue->num_dmabufs); + }
- iio_buffer_put(&block->queue->buffer); + iio_buffer_put(&queue->buffer); kfree(block); }
@@ -163,7 +172,7 @@ static struct iio_dma_buffer_queue *iio_buffer_to_queue(struct iio_buffer *buf) }
static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( - struct iio_dma_buffer_queue *queue, size_t size) + struct iio_dma_buffer_queue *queue, size_t size, bool fileio) { struct iio_dma_buffer_block *block;
@@ -171,13 +180,16 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( if (!block) return NULL;
- block->vaddr = dma_alloc_coherent(queue->dev, PAGE_ALIGN(size), - &block->phys_addr, GFP_KERNEL); - if (!block->vaddr) { - kfree(block); - return NULL; + if (fileio) { + block->vaddr = dma_alloc_coherent(queue->dev, PAGE_ALIGN(size), + &block->phys_addr, GFP_KERNEL); + if (!block->vaddr) { + kfree(block); + return NULL; + } }
+ block->fileio = fileio; block->size = size; block->state = IIO_BLOCK_STATE_DONE; block->queue = queue; @@ -186,6 +198,9 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block(
iio_buffer_get(&queue->buffer);
+ if (!fileio) + atomic_inc(&queue->num_dmabufs); + return block; }
@@ -206,13 +221,21 @@ void iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) { struct iio_dma_buffer_queue *queue = block->queue; unsigned long flags; + bool cookie; + + cookie = dma_fence_begin_signalling();
spin_lock_irqsave(&queue->list_lock, flags); _iio_dma_buffer_block_done(block); spin_unlock_irqrestore(&queue->list_lock, flags);
+ if (!block->fileio) + iio_buffer_signal_dmabuf_done(block->fence, 0); + iio_buffer_block_put_atomic(block); wake_up_interruptible_poll(&queue->buffer.pollq, EPOLLIN | EPOLLRDNORM); + + dma_fence_end_signalling(cookie); } EXPORT_SYMBOL_GPL(iio_dma_buffer_block_done);
@@ -231,17 +254,27 @@ void iio_dma_buffer_block_list_abort(struct iio_dma_buffer_queue *queue, { struct iio_dma_buffer_block *block, *_block; unsigned long flags; + bool cookie; + + cookie = dma_fence_begin_signalling();
spin_lock_irqsave(&queue->list_lock, flags); list_for_each_entry_safe(block, _block, list, head) { list_del(&block->head); block->bytes_used = 0; _iio_dma_buffer_block_done(block); + + if (!block->fileio) + iio_buffer_signal_dmabuf_done(block->fence, -EINTR); iio_buffer_block_put_atomic(block); } spin_unlock_irqrestore(&queue->list_lock, flags);
+ if (queue->fileio.enabled) + queue->fileio.enabled = false; + wake_up_interruptible_poll(&queue->buffer.pollq, EPOLLIN | EPOLLRDNORM); + dma_fence_end_signalling(cookie); } EXPORT_SYMBOL_GPL(iio_dma_buffer_block_list_abort);
@@ -261,6 +294,16 @@ static bool iio_dma_block_reusable(struct iio_dma_buffer_block *block) } }
+static bool iio_dma_buffer_can_use_fileio(struct iio_dma_buffer_queue *queue) +{ + /* + * Note that queue->num_dmabufs cannot increase while the queue is + * locked, it can only decrease, so it does not race against + * iio_dma_buffer_alloc_block(). + */ + return queue->fileio.enabled || !atomic_read(&queue->num_dmabufs); +} + /** * iio_dma_buffer_request_update() - DMA buffer request_update callback * @buffer: The buffer which to request an update @@ -287,6 +330,12 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer)
mutex_lock(&queue->lock);
+ queue->fileio.enabled = iio_dma_buffer_can_use_fileio(queue); + + /* If DMABUFs were created, disable fileio interface */ + if (!queue->fileio.enabled) + goto out_unlock; + /* Allocations are page aligned */ if (PAGE_ALIGN(queue->fileio.block_size) == PAGE_ALIGN(size)) try_reuse = true; @@ -327,7 +376,7 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) }
if (!block) { - block = iio_dma_buffer_alloc_block(queue, size); + block = iio_dma_buffer_alloc_block(queue, size, true); if (!block) { ret = -ENOMEM; goto out_unlock; @@ -384,8 +433,12 @@ static void iio_dma_buffer_submit_block(struct iio_dma_buffer_queue *queue,
block->state = IIO_BLOCK_STATE_ACTIVE; iio_buffer_block_get(block); + ret = queue->ops->submit(queue, block); if (ret) { + if (!block->fileio) + iio_buffer_signal_dmabuf_done(block->fence, ret); + /* * This is a bit of a problem and there is not much we can do * other then wait for the buffer to be disabled and re-enabled @@ -588,6 +641,112 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) } EXPORT_SYMBOL_GPL(iio_dma_buffer_data_available);
+struct iio_dma_buffer_block * +iio_dma_buffer_attach_dmabuf(struct iio_buffer *buffer, + struct dma_buf_attachment *attach) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + struct iio_dma_buffer_block *block; + + guard(mutex)(&queue->lock); + + /* + * If the buffer is enabled and in fileio mode new blocks can't be + * allocated. + */ + if (queue->fileio.enabled) + return ERR_PTR(-EBUSY); + + block = iio_dma_buffer_alloc_block(queue, attach->dmabuf->size, false); + if (!block) + return ERR_PTR(-ENOMEM); + + block->attach = attach; + + /* Free memory that might be in use for fileio mode */ + iio_dma_buffer_fileio_free(queue); + + return block; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_attach_dmabuf); + +void iio_dma_buffer_detach_dmabuf(struct iio_buffer *buffer, + struct iio_dma_buffer_block *block) +{ + block->state = IIO_BLOCK_STATE_DEAD; + iio_buffer_block_put_atomic(block); +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_detach_dmabuf); + +static int iio_dma_can_enqueue_block(struct iio_dma_buffer_block *block) +{ + struct iio_dma_buffer_queue *queue = block->queue; + + /* If in fileio mode buffers can't be enqueued. */ + if (queue->fileio.enabled) + return -EBUSY; + + switch (block->state) { + case IIO_BLOCK_STATE_QUEUED: + return -EPERM; + case IIO_BLOCK_STATE_ACTIVE: + case IIO_BLOCK_STATE_DEAD: + return -EBUSY; + case IIO_BLOCK_STATE_DONE: + break; + } + + return 0; +} + +int iio_dma_buffer_enqueue_dmabuf(struct iio_buffer *buffer, + struct iio_dma_buffer_block *block, + struct dma_fence *fence, + struct sg_table *sgt, + size_t size, bool cyclic) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + bool cookie; + int ret; + + WARN_ON(!mutex_is_locked(&queue->lock)); + + cookie = dma_fence_begin_signalling(); + + ret = iio_dma_can_enqueue_block(block); + if (ret < 0) + goto out_end_signalling; + + block->bytes_used = size; + block->cyclic = cyclic; + block->sg_table = sgt; + block->fence = fence; + + iio_dma_buffer_enqueue(queue, block); + +out_end_signalling: + dma_fence_end_signalling(cookie); + + return ret; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_enqueue_dmabuf); + +void iio_dma_buffer_lock_queue(struct iio_buffer *buffer) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + + mutex_lock(&queue->lock); +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_lock_queue); + +void iio_dma_buffer_unlock_queue(struct iio_buffer *buffer) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + + mutex_unlock(&queue->lock); +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_unlock_queue); + /** * iio_dma_buffer_set_bytes_per_datum() - DMA buffer set_bytes_per_datum callback * @buffer: Buffer to set the bytes-per-datum for diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index 18d3702fa95d..b62ff2a3f554 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -7,6 +7,7 @@ #ifndef __INDUSTRIALIO_DMA_BUFFER_H__ #define __INDUSTRIALIO_DMA_BUFFER_H__
+#include <linux/atomic.h> #include <linux/list.h> #include <linux/kref.h> #include <linux/spinlock.h> @@ -16,6 +17,9 @@ struct iio_dma_buffer_queue; struct iio_dma_buffer_ops; struct device; +struct dma_buf_attachment; +struct dma_fence; +struct sg_table;
/** * enum iio_block_state - State of a struct iio_dma_buffer_block @@ -41,6 +45,8 @@ enum iio_block_state { * @queue: Parent DMA buffer queue * @kref: kref used to manage the lifetime of block * @state: Current state of the block + * @cyclic: True if this is a cyclic buffer + * @fileio: True if this buffer is used for fileio mode */ struct iio_dma_buffer_block { /* May only be accessed by the owner of the block */ @@ -63,6 +69,14 @@ struct iio_dma_buffer_block { * queue->list_lock if the block is not owned by the core. */ enum iio_block_state state; + + bool cyclic; + bool fileio; + + struct dma_buf_attachment *attach; + struct sg_table *sg_table; + + struct dma_fence *fence; };
/** @@ -72,6 +86,7 @@ struct iio_dma_buffer_block { * @pos: Read offset in the active block * @block_size: Size of each block * @next_dequeue: index of next block that will be dequeued + * @enabled: Whether the buffer is operating in fileio mode */ struct iio_dma_buffer_queue_fileio { struct iio_dma_buffer_block *blocks[2]; @@ -80,6 +95,7 @@ struct iio_dma_buffer_queue_fileio { size_t block_size;
unsigned int next_dequeue; + bool enabled; };
/** @@ -95,6 +111,7 @@ struct iio_dma_buffer_queue_fileio { * the DMA controller * @incoming: List of buffers on the incoming queue * @active: Whether the buffer is currently active + * @num_dmabufs: Total number of DMABUFs attached to this queue * @fileio: FileIO state */ struct iio_dma_buffer_queue { @@ -107,6 +124,7 @@ struct iio_dma_buffer_queue { struct list_head incoming;
bool active; + atomic_t num_dmabufs;
struct iio_dma_buffer_queue_fileio fileio; }; @@ -142,4 +160,17 @@ int iio_dma_buffer_init(struct iio_dma_buffer_queue *queue, void iio_dma_buffer_exit(struct iio_dma_buffer_queue *queue); void iio_dma_buffer_release(struct iio_dma_buffer_queue *queue);
+struct iio_dma_buffer_block * +iio_dma_buffer_attach_dmabuf(struct iio_buffer *buffer, + struct dma_buf_attachment *attach); +void iio_dma_buffer_detach_dmabuf(struct iio_buffer *buffer, + struct iio_dma_buffer_block *block); +int iio_dma_buffer_enqueue_dmabuf(struct iio_buffer *buffer, + struct iio_dma_buffer_block *block, + struct dma_fence *fence, + struct sg_table *sgt, + size_t size, bool cyclic); +void iio_dma_buffer_lock_queue(struct iio_buffer *buffer); +void iio_dma_buffer_unlock_queue(struct iio_buffer *buffer); + #endif