Enhance the current fileio code by using DMABUF objects instead of custom buffers.
This adds more code than it removes, but: - a lot of the complexity can be dropped, e.g. custom kref and iio_buffer_block_put_atomic() are not needed anymore; - it will be much easier to introduce an API to export these DMABUF objects to userspace in a following patch.
Signed-off-by: Paul Cercueil paul@crapouillou.net --- drivers/iio/buffer/industrialio-buffer-dma.c | 196 ++++++++++++------- include/linux/iio/buffer-dma.h | 8 +- 2 files changed, 127 insertions(+), 77 deletions(-)
diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index eb8cfd3af030..adb20434f2d2 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -14,6 +14,7 @@ #include <linux/poll.h> #include <linux/iio/buffer_impl.h> #include <linux/iio/buffer-dma.h> +#include <linux/dma-buf.h> #include <linux/dma-mapping.h> #include <linux/sizes.h>
@@ -90,104 +91,150 @@ * callback is called from within the custom callback. */
-static void iio_buffer_block_release(struct kref *kref) -{ - struct iio_dma_buffer_block *block = container_of(kref, - struct iio_dma_buffer_block, kref); - - WARN_ON(block->state != IIO_BLOCK_STATE_DEAD); - - dma_free_coherent(block->queue->dev, PAGE_ALIGN(block->size), - block->vaddr, block->phys_addr); - - iio_buffer_put(&block->queue->buffer); - kfree(block); -} - -static void iio_buffer_block_get(struct iio_dma_buffer_block *block) -{ - kref_get(&block->kref); -} - -static void iio_buffer_block_put(struct iio_dma_buffer_block *block) -{ - kref_put(&block->kref, iio_buffer_block_release); -} - -/* - * dma_free_coherent can sleep, hence we need to take some special care to be - * able to drop a reference from an atomic context. - */ -static LIST_HEAD(iio_dma_buffer_dead_blocks); -static DEFINE_SPINLOCK(iio_dma_buffer_dead_blocks_lock); - -static void iio_dma_buffer_cleanup_worker(struct work_struct *work) -{ - struct iio_dma_buffer_block *block, *_block; - LIST_HEAD(block_list); - - spin_lock_irq(&iio_dma_buffer_dead_blocks_lock); - list_splice_tail_init(&iio_dma_buffer_dead_blocks, &block_list); - spin_unlock_irq(&iio_dma_buffer_dead_blocks_lock); - - list_for_each_entry_safe(block, _block, &block_list, head) - iio_buffer_block_release(&block->kref); -} -static DECLARE_WORK(iio_dma_buffer_cleanup_work, iio_dma_buffer_cleanup_worker); - -static void iio_buffer_block_release_atomic(struct kref *kref) -{ +struct iio_buffer_dma_buf_attachment { + struct scatterlist sgl; + struct sg_table sg_table; struct iio_dma_buffer_block *block; - unsigned long flags; - - block = container_of(kref, struct iio_dma_buffer_block, kref); - - spin_lock_irqsave(&iio_dma_buffer_dead_blocks_lock, flags); - list_add_tail(&block->head, &iio_dma_buffer_dead_blocks); - spin_unlock_irqrestore(&iio_dma_buffer_dead_blocks_lock, flags); - - schedule_work(&iio_dma_buffer_cleanup_work); -} - -/* - * Version of iio_buffer_block_put() that can be called from atomic context - */ -static void iio_buffer_block_put_atomic(struct iio_dma_buffer_block *block) -{ - kref_put(&block->kref, iio_buffer_block_release_atomic); -} +};
static struct iio_dma_buffer_queue *iio_buffer_to_queue(struct iio_buffer *buf) { return container_of(buf, struct iio_dma_buffer_queue, buffer); }
+static struct iio_buffer_dma_buf_attachment * +to_iio_buffer_dma_buf_attachment(struct sg_table *table) +{ + return container_of(table, struct iio_buffer_dma_buf_attachment, sg_table); +} + +static void iio_buffer_block_get(struct iio_dma_buffer_block *block) +{ + get_dma_buf(block->dmabuf); +} + +static void iio_buffer_block_put(struct iio_dma_buffer_block *block) +{ + dma_buf_put(block->dmabuf); +} + +static int iio_buffer_dma_buf_attach(struct dma_buf *dbuf, + struct dma_buf_attachment *at) +{ + at->priv = dbuf->priv; + + return 0; +} + +static struct sg_table *iio_buffer_dma_buf_map(struct dma_buf_attachment *at, + enum dma_data_direction dma_dir) +{ + struct iio_dma_buffer_block *block = at->priv; + struct iio_buffer_dma_buf_attachment *dba; + int ret; + + dba = kzalloc(sizeof(*dba), GFP_KERNEL); + if (!dba) + return ERR_PTR(-ENOMEM); + + sg_init_one(&dba->sgl, block->vaddr, PAGE_ALIGN(block->size)); + dba->sg_table.sgl = &dba->sgl; + dba->sg_table.nents = 1; + dba->block = block; + + ret = dma_map_sgtable(at->dev, &dba->sg_table, dma_dir, 0); + if (ret) { + kfree(dba); + return ERR_PTR(ret); + } + + return &dba->sg_table; +} + +static void iio_buffer_dma_buf_unmap(struct dma_buf_attachment *at, + struct sg_table *sg_table, + enum dma_data_direction dma_dir) +{ + struct iio_buffer_dma_buf_attachment *dba = + to_iio_buffer_dma_buf_attachment(sg_table); + + dma_unmap_sgtable(at->dev, &dba->sg_table, dma_dir, 0); + kfree(dba); +} + +static void iio_buffer_dma_buf_release(struct dma_buf *dbuf) +{ + struct iio_dma_buffer_block *block = dbuf->priv; + struct iio_dma_buffer_queue *queue = block->queue; + + WARN_ON(block->state != IIO_BLOCK_STATE_DEAD); + + mutex_lock(&queue->lock); + + dma_free_coherent(queue->dev, PAGE_ALIGN(block->size), + block->vaddr, block->phys_addr); + + kfree(block); + + mutex_unlock(&queue->lock); + iio_buffer_put(&queue->buffer); +} + + +static const struct dma_buf_ops iio_dma_buffer_dmabuf_ops = { + .attach = iio_buffer_dma_buf_attach, + .map_dma_buf = iio_buffer_dma_buf_map, + .unmap_dma_buf = iio_buffer_dma_buf_unmap, + .release = iio_buffer_dma_buf_release, +}; + static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( struct iio_dma_buffer_queue *queue, size_t size) { struct iio_dma_buffer_block *block; + DEFINE_DMA_BUF_EXPORT_INFO(einfo); + struct dma_buf *dmabuf; + int err;
block = kzalloc(sizeof(*block), GFP_KERNEL); if (!block) - return NULL; + return ERR_PTR(-ENOMEM);
block->vaddr = dma_alloc_coherent(queue->dev, PAGE_ALIGN(size), &block->phys_addr, GFP_KERNEL); if (!block->vaddr) { - kfree(block); - return NULL; + err = -ENOMEM; + goto err_free_block; }
+ einfo.ops = &iio_dma_buffer_dmabuf_ops; + einfo.size = PAGE_ALIGN(size); + einfo.priv = block; + einfo.flags = O_RDWR; + + dmabuf = dma_buf_export(&einfo); + if (IS_ERR(dmabuf)) { + err = PTR_ERR(dmabuf); + goto err_free_dma; + } + + block->dmabuf = dmabuf; block->size = size; block->bytes_used = size; block->state = IIO_BLOCK_STATE_DONE; block->queue = queue; INIT_LIST_HEAD(&block->head); - kref_init(&block->kref);
iio_buffer_get(&queue->buffer);
return block; + +err_free_dma: + dma_free_coherent(queue->dev, PAGE_ALIGN(size), + block->vaddr, block->phys_addr); +err_free_block: + kfree(block); + return ERR_PTR(err); }
static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) @@ -224,7 +271,7 @@ void iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) _iio_dma_buffer_block_done(block); spin_unlock_irqrestore(&queue->list_lock, flags);
- iio_buffer_block_put_atomic(block); + iio_buffer_block_put(block); iio_dma_buffer_queue_wake(queue); } EXPORT_SYMBOL_GPL(iio_dma_buffer_block_done); @@ -250,7 +297,8 @@ void iio_dma_buffer_block_list_abort(struct iio_dma_buffer_queue *queue, list_del(&block->head); block->bytes_used = 0; _iio_dma_buffer_block_done(block); - iio_buffer_block_put_atomic(block); + + iio_buffer_block_put(block); } spin_unlock_irqrestore(&queue->list_lock, flags);
@@ -340,11 +388,13 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer)
if (!block) { block = iio_dma_buffer_alloc_block(queue, size); - if (!block) { - ret = -ENOMEM; + if (IS_ERR(block)) { + ret = PTR_ERR(block); goto out_unlock; } queue->fileio.blocks[i] = block; + + iio_buffer_block_get(block); }
if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index 09c07d5563c0..22effd6cfbb6 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -8,7 +8,6 @@ #define __INDUSTRIALIO_DMA_BUFFER_H__
#include <linux/list.h> -#include <linux/kref.h> #include <linux/spinlock.h> #include <linux/mutex.h> #include <linux/iio/buffer_impl.h> @@ -16,6 +15,7 @@ struct iio_dma_buffer_queue; struct iio_dma_buffer_ops; struct device; +struct dma_buf;
/** * enum iio_block_state - State of a struct iio_dma_buffer_block @@ -41,8 +41,8 @@ enum iio_block_state { * @vaddr: Virutal address of the blocks memory * @phys_addr: Physical address of the blocks memory * @queue: Parent DMA buffer queue - * @kref: kref used to manage the lifetime of block * @state: Current state of the block + * @dmabuf: Underlying DMABUF object */ struct iio_dma_buffer_block { /* May only be accessed by the owner of the block */ @@ -58,13 +58,13 @@ struct iio_dma_buffer_block { size_t size; struct iio_dma_buffer_queue *queue;
- /* Must not be accessed outside the core. */ - struct kref kref; /* * Must not be accessed outside the core. Access needs to hold * queue->list_lock if the block is not owned by the core. */ enum iio_block_state state; + + struct dma_buf *dmabuf; };
/**