Hi Jonathan,
Here's the v11 of my patchset that introduces DMABUF support to IIO.
It addresses the few points that were raised in the review of the v10. It also adds Nuno as a co-developer.
Changelog: - [3/7]: - Document .lock_queue / .unlock_queue buffer callbacks - Add small comment to explain what the spinlock protects - Use guard(mutex)
- [4/7]: - Remove useless field "attach" in struct iio_dma_buffer_block - Document "sg_table" and "fence" fields in struct iio_block_state
- [6/7]: - "a IIO buffer" -> "an IIO buffer" - Add variable name in IOCTL calls
- [7/7]: New patch, to document the DMA changes
Cheers, -Paul
Paul Cercueil (7): dmaengine: Add API function dmaengine_prep_peripheral_dma_vec() dmaengine: dma-axi-dmac: Implement device_prep_peripheral_dma_vec iio: core: Add new DMABUF interface infrastructure iio: buffer-dma: Enable support for DMABUFs iio: buffer-dmaengine: Support new DMABUF based userspace API Documentation: iio: Document high-speed DMABUF based API Documentation: dmaengine: Document new dma_vec API
Documentation/driver-api/dmaengine/client.rst | 9 + .../driver-api/dmaengine/provider.rst | 10 + Documentation/iio/iio_dmabuf_api.rst | 54 +++ Documentation/iio/index.rst | 1 + drivers/dma/dma-axi-dmac.c | 40 ++ drivers/iio/Kconfig | 1 + drivers/iio/buffer/industrialio-buffer-dma.c | 178 ++++++- .../buffer/industrialio-buffer-dmaengine.c | 62 ++- drivers/iio/industrialio-buffer.c | 457 ++++++++++++++++++ include/linux/dmaengine.h | 33 ++ include/linux/iio/buffer-dma.h | 31 ++ include/linux/iio/buffer_impl.h | 33 ++ include/uapi/linux/iio/buffer.h | 22 + 13 files changed, 911 insertions(+), 20 deletions(-) create mode 100644 Documentation/iio/iio_dmabuf_api.rst
This function can be used to initiate a scatter-gather DMA transfer, where the address and size of each segment is located in one entry of the dma_vec array.
The major difference with dmaengine_prep_slave_sg() is that it supports specifying the lengths of each DMA transfer; as trying to override the length of the transfer with dmaengine_prep_slave_sg() is a very tedious process. The introduction of a new API function is also justified by the fact that scatterlists are on their way out.
Note that dmaengine_prep_interleaved_dma() is not helpful either in that case, as it assumes that the address of each segment will be higher than the one of the previous segment, which we just cannot guarantee in case of a scatter-gather transfer.
Signed-off-by: Paul Cercueil paul@crapouillou.net Co-developed-by: Nuno Sa nuno.sa@analog.com Signed-off-by: Nuno Sa nuno.sa@analog.com
--- v3: New patch
v5: Replace with function dmaengine_prep_slave_dma_vec(), and struct 'dma_vec'. Note that at some point we will need to support cyclic transfers using dmaengine_prep_slave_dma_vec(). Maybe with a new "flags" parameter to the function?
v7: - Renamed *device_prep_slave_dma_vec() -> device_prep_peripheral_dma_vec(); - Added a new flag parameter to the function as agreed between Paul and Vinod. I renamed the first parameter to prep_flags as it's supposed to be used (I think) with enum dma_ctrl_flags. I'm not really sure how that API can grow but I was thinking in just having a bool cyclic parameter (as the first intention of the flags is to support cyclic transfers) but ended up "respecting" the previously agreed approach.
v10: - Add kernel doc to dmaengine_prep_peripheral_dma_vec() - Remove extra flags parameter --- include/linux/dmaengine.h | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 73537fddbb52..b137fdb56093 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -160,6 +160,16 @@ struct dma_interleaved_template { struct data_chunk sgl[]; };
+/** + * struct dma_vec - DMA vector + * @addr: Bus address of the start of the vector + * @len: Length in bytes of the DMA vector + */ +struct dma_vec { + dma_addr_t addr; + size_t len; +}; + /** * enum dma_ctrl_flags - DMA flags to augment operation preparation, * control completion, and communicate status. @@ -910,6 +920,10 @@ struct dma_device { struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)( struct dma_chan *chan, unsigned long flags);
+ struct dma_async_tx_descriptor *(*device_prep_peripheral_dma_vec)( + struct dma_chan *chan, const struct dma_vec *vecs, + size_t nents, enum dma_transfer_direction direction, + unsigned long flags); struct dma_async_tx_descriptor *(*device_prep_slave_sg)( struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction direction, @@ -973,6 +987,25 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( dir, flags, NULL); }
+/** + * dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor + * @chan: The channel to be used for this descriptor + * @vecs: The array of DMA vectors that should be transferred + * @nents: The number of DMA vectors in the array + * @dir: Specifies the direction of the data transfer + * @flags: DMA engine flags + */ +static inline struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec( + struct dma_chan *chan, const struct dma_vec *vecs, size_t nents, + enum dma_transfer_direction dir, unsigned long flags) +{ + if (!chan || !chan->device || !chan->device->device_prep_peripheral_dma_vec) + return NULL; + + return chan->device->device_prep_peripheral_dma_vec(chan, vecs, nents, + dir, flags); +} + static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg( struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction dir, unsigned long flags)
Add implementation of the .device_prep_peripheral_dma_vec() callback.
Signed-off-by: Paul Cercueil paul@crapouillou.net Co-developed-by: Nuno Sa nuno.sa@analog.com Signed-off-by: Nuno Sa nuno.sa@analog.com
--- v3: New patch
v5: Implement .device_prep_slave_dma_vec() instead of v3's .device_prep_slave_dma_array().
v6: Use new prototype for axi_dmac_alloc_desc() as it changed upstream.
v7: Adapted patch for the changes made in patch 1.
v10: Use the new function prototype (without the extra prep_flags). --- drivers/dma/dma-axi-dmac.c | 40 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+)
diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c index bdb752f11869..36943b0c6d60 100644 --- a/drivers/dma/dma-axi-dmac.c +++ b/drivers/dma/dma-axi-dmac.c @@ -620,6 +620,45 @@ static struct axi_dmac_sg *axi_dmac_fill_linear_sg(struct axi_dmac_chan *chan, return sg; }
+static struct dma_async_tx_descriptor * +axi_dmac_prep_peripheral_dma_vec(struct dma_chan *c, const struct dma_vec *vecs, + size_t nb, enum dma_transfer_direction direction, + unsigned long flags) +{ + struct axi_dmac_chan *chan = to_axi_dmac_chan(c); + struct axi_dmac_desc *desc; + unsigned int num_sgs = 0; + struct axi_dmac_sg *dsg; + size_t i; + + if (direction != chan->direction) + return NULL; + + for (i = 0; i < nb; i++) + num_sgs += DIV_ROUND_UP(vecs[i].len, chan->max_length); + + desc = axi_dmac_alloc_desc(chan, num_sgs); + if (!desc) + return NULL; + + dsg = desc->sg; + + for (i = 0; i < nb; i++) { + if (!axi_dmac_check_addr(chan, vecs[i].addr) || + !axi_dmac_check_len(chan, vecs[i].len)) { + kfree(desc); + return NULL; + } + + dsg = axi_dmac_fill_linear_sg(chan, direction, vecs[i].addr, 1, + vecs[i].len, dsg); + } + + desc->cyclic = false; + + return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags); +} + static struct dma_async_tx_descriptor *axi_dmac_prep_slave_sg( struct dma_chan *c, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction direction, @@ -1061,6 +1100,7 @@ static int axi_dmac_probe(struct platform_device *pdev) dma_dev->device_tx_status = dma_cookie_status; dma_dev->device_issue_pending = axi_dmac_issue_pending; dma_dev->device_prep_slave_sg = axi_dmac_prep_slave_sg; + dma_dev->device_prep_peripheral_dma_vec = axi_dmac_prep_peripheral_dma_vec; dma_dev->device_prep_dma_cyclic = axi_dmac_prep_dma_cyclic; dma_dev->device_prep_interleaved_dma = axi_dmac_prep_interleaved; dma_dev->device_terminate_all = axi_dmac_terminate_all;
Add the necessary infrastructure to the IIO core to support a new optional DMABUF based interface.
With this new interface, DMABUF objects (externally created) can be attached to a IIO buffer, and subsequently used for data transfer.
A userspace application can then use this interface to share DMABUF objects between several interfaces, allowing it to transfer data in a zero-copy fashion, for instance between IIO and the USB stack.
The userspace application can also memory-map the DMABUF objects, and access the sample data directly. The advantage of doing this vs. the read() interface is that it avoids an extra copy of the data between the kernel and userspace. This is particularly userful for high-speed devices which produce several megabytes or even gigabytes of data per second.
As part of the interface, 3 new IOCTLs have been added:
IIO_BUFFER_DMABUF_ATTACH_IOCTL(int fd): Attach the DMABUF object identified by the given file descriptor to the buffer.
IIO_BUFFER_DMABUF_DETACH_IOCTL(int fd): Detach the DMABUF object identified by the given file descriptor from the buffer. Note that closing the IIO buffer's file descriptor will automatically detach all previously attached DMABUF objects.
IIO_BUFFER_DMABUF_ENQUEUE_IOCTL(struct iio_dmabuf *): Request a data transfer to/from the given DMABUF object. Its file descriptor, as well as the transfer size and flags are provided in the "iio_dmabuf" structure.
These three IOCTLs have to be performed on the IIO buffer's file descriptor, obtained using the IIO_BUFFER_GET_FD_IOCTL() ioctl.
Signed-off-by: Paul Cercueil paul@crapouillou.net Co-developed-by: Nuno Sa nuno.sa@analog.com Signed-off-by: Nuno Sa nuno.sa@analog.com
--- v2: Only allow the new IOCTLs on the buffer FD created with IIO_BUFFER_GET_FD_IOCTL().
v3: - Get rid of the old IOCTLs. The IIO subsystem does not create or manage DMABUFs anymore, and only attaches/detaches externally created DMABUFs. - Add IIO_BUFFER_DMABUF_CYCLIC to the supported flags.
v5: - Use dev_err() instead of pr_err() - Inline to_iio_dma_fence() - Add comment to explain why we unref twice when detaching dmabuf - Remove TODO comment. It is actually safe to free the file's private data even when transfers are still pending because it won't be accessed. - Fix documentation of new fields in struct iio_buffer_access_funcs - iio_dma_resv_lock() does not need to be exported, make it static
v6: - Remove dead code in iio_dma_resv_lock() - Fix non-block actually blocking - Cache dma_buf_attachment instead of mapping/unmapping it for every transfer - Return -EINVAL instead of IIO_IOCTL_UNHANDLED for unknown ioctl - Make .block_enqueue() callback take a dma_fence pointer, which will be passed to iio_buffer_signal_dmabuf_done() instead of the dma_buf_attachment; and remove the backpointer from the priv structure to the dma_fence. - Use dma_fence_begin/end_signalling in the dma_fence critical sections - Unref dma_fence and dma_buf_attachment in worker, because they might try to lock the dma_resv, which would deadlock. - Add buffer ops to lock/unlock the queue. This is motivated by the fact that once the dma_fence has been installed, we cannot lock anything anymore - so the queue must be locked before the dma_fence is installed. - Use 'long retl' variable to handle the return value of dma_resv_wait_timeout() - Protect dmabufs list access with a mutex - Rework iio_buffer_find_attachment() to use the internal dmabufs list, instead of messing with dmabufs private data. - Add an atomically-increasing sequence number for fences
v8 - Fix swapped fence direction - Simplify fence wait mechanism - Remove "Buffer closed with active transfers" print, as it was dead code - Un-export iio_buffer_dmabuf_{get,put}. They are not used anywhere else so they can even be static. - Prevent attaching already-attached DMABUFs
v9: - Select DMA_SHARED_BUFFER in Kconfig - Remove useless forward declaration of 'iio_dma_fence' - Import DMA-BUF namespace - Add missing __user tag to iio_buffer_detach_dmabuf() argument
v11: - Document .lock_queue / .unlock_queue buffer callbacks - Add small comment to explain what the spinlock protects - Use guard(mutex) --- drivers/iio/Kconfig | 1 + drivers/iio/industrialio-buffer.c | 457 ++++++++++++++++++++++++++++++ include/linux/iio/buffer_impl.h | 33 +++ include/uapi/linux/iio/buffer.h | 22 ++ 4 files changed, 513 insertions(+)
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig index 9c351ffc7bed..661127aed2f9 100644 --- a/drivers/iio/Kconfig +++ b/drivers/iio/Kconfig @@ -14,6 +14,7 @@ if IIO
config IIO_BUFFER bool "Enable buffer support within IIO" + select DMA_SHARED_BUFFER help Provide core support for various buffer based data acquisition methods. diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 0138b21b244f..2c36354adc9e 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -9,15 +9,20 @@ * - Better memory allocation techniques? * - Alternative access techniques? */ +#include <linux/atomic.h> #include <linux/anon_inodes.h> #include <linux/cleanup.h> #include <linux/kernel.h> #include <linux/export.h> #include <linux/device.h> +#include <linux/dma-buf.h> +#include <linux/dma-fence.h> +#include <linux/dma-resv.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/cdev.h> #include <linux/slab.h> +#include <linux/mm.h> #include <linux/poll.h> #include <linux/sched/signal.h>
@@ -29,6 +34,34 @@ #include <linux/iio/buffer.h> #include <linux/iio/buffer_impl.h>
+#define DMABUF_ENQUEUE_TIMEOUT_MS 5000 + +MODULE_IMPORT_NS(DMA_BUF); + +struct iio_dmabuf_priv { + struct list_head entry; + struct kref ref; + + struct iio_buffer *buffer; + struct iio_dma_buffer_block *block; + + u64 context; + + /* Spinlock used for locking the dma_fence */ + spinlock_t lock; + + struct dma_buf_attachment *attach; + struct sg_table *sgt; + enum dma_data_direction dir; + atomic_t seqno; +}; + +struct iio_dma_fence { + struct dma_fence base; + struct iio_dmabuf_priv *priv; + struct work_struct work; +}; + static const char * const iio_endian_prefix[] = { [IIO_BE] = "be", [IIO_LE] = "le", @@ -333,6 +366,8 @@ void iio_buffer_init(struct iio_buffer *buffer) { INIT_LIST_HEAD(&buffer->demux_list); INIT_LIST_HEAD(&buffer->buffer_list); + INIT_LIST_HEAD(&buffer->dmabufs); + mutex_init(&buffer->dmabufs_mutex); init_waitqueue_head(&buffer->pollq); kref_init(&buffer->ref); if (!buffer->watermark) @@ -1526,14 +1561,55 @@ static void iio_buffer_unregister_legacy_sysfs_groups(struct iio_dev *indio_dev) kfree(iio_dev_opaque->legacy_scan_el_group.attrs); }
+static void iio_buffer_dmabuf_release(struct kref *ref) +{ + struct iio_dmabuf_priv *priv = container_of(ref, struct iio_dmabuf_priv, ref); + struct dma_buf_attachment *attach = priv->attach; + struct iio_buffer *buffer = priv->buffer; + struct dma_buf *dmabuf = attach->dmabuf; + + dma_resv_lock(dmabuf->resv, NULL); + dma_buf_unmap_attachment(attach, priv->sgt, priv->dir); + dma_resv_unlock(dmabuf->resv); + + buffer->access->detach_dmabuf(buffer, priv->block); + + dma_buf_detach(attach->dmabuf, attach); + dma_buf_put(dmabuf); + kfree(priv); +} + +static void iio_buffer_dmabuf_get(struct dma_buf_attachment *attach) +{ + struct iio_dmabuf_priv *priv = attach->importer_priv; + + kref_get(&priv->ref); +} + +static void iio_buffer_dmabuf_put(struct dma_buf_attachment *attach) +{ + struct iio_dmabuf_priv *priv = attach->importer_priv; + + kref_put(&priv->ref, iio_buffer_dmabuf_release); +} + static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) { struct iio_dev_buffer_pair *ib = filep->private_data; struct iio_dev *indio_dev = ib->indio_dev; struct iio_buffer *buffer = ib->buffer; + struct iio_dmabuf_priv *priv, *tmp;
wake_up(&buffer->pollq);
+ guard(mutex)(&buffer->dmabufs_mutex); + + /* Close all attached DMABUFs */ + list_for_each_entry_safe(priv, tmp, &buffer->dmabufs, entry) { + list_del_init(&priv->entry); + iio_buffer_dmabuf_put(priv->attach); + } + kfree(ib); clear_bit(IIO_BUSY_BIT_POS, &buffer->flags); iio_device_put(indio_dev); @@ -1541,11 +1617,391 @@ static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) return 0; }
+static int iio_dma_resv_lock(struct dma_buf *dmabuf, bool nonblock) +{ + if (!nonblock) + return dma_resv_lock_interruptible(dmabuf->resv, NULL); + + if (!dma_resv_trylock(dmabuf->resv)) + return -EBUSY; + + return 0; +} + +static struct dma_buf_attachment * +iio_buffer_find_attachment(struct iio_dev_buffer_pair *ib, + struct dma_buf *dmabuf, bool nonblock) +{ + struct device *dev = ib->indio_dev->dev.parent; + struct iio_buffer *buffer = ib->buffer; + struct dma_buf_attachment *attach = NULL; + struct iio_dmabuf_priv *priv; + + guard(mutex)(&buffer->dmabufs_mutex); + + list_for_each_entry(priv, &buffer->dmabufs, entry) { + if (priv->attach->dev == dev + && priv->attach->dmabuf == dmabuf) { + attach = priv->attach; + break; + } + } + + if (attach) + iio_buffer_dmabuf_get(attach); + + return attach ?: ERR_PTR(-EPERM); +} + +static int iio_buffer_attach_dmabuf(struct iio_dev_buffer_pair *ib, + int __user *user_fd, bool nonblock) +{ + struct iio_dev *indio_dev = ib->indio_dev; + struct iio_buffer *buffer = ib->buffer; + struct dma_buf_attachment *attach; + struct iio_dmabuf_priv *priv, *each; + struct dma_buf *dmabuf; + int err, fd; + + if (!buffer->access->attach_dmabuf + || !buffer->access->detach_dmabuf + || !buffer->access->enqueue_dmabuf) + return -EPERM; + + if (copy_from_user(&fd, user_fd, sizeof(fd))) + return -EFAULT; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + spin_lock_init(&priv->lock); + priv->context = dma_fence_context_alloc(1); + + dmabuf = dma_buf_get(fd); + if (IS_ERR(dmabuf)) { + err = PTR_ERR(dmabuf); + goto err_free_priv; + } + + attach = dma_buf_attach(dmabuf, indio_dev->dev.parent); + if (IS_ERR(attach)) { + err = PTR_ERR(attach); + goto err_dmabuf_put; + } + + err = iio_dma_resv_lock(dmabuf, nonblock); + if (err) + goto err_dmabuf_detach; + + priv->dir = buffer->direction == IIO_BUFFER_DIRECTION_IN + ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + priv->sgt = dma_buf_map_attachment(attach, priv->dir); + if (IS_ERR(priv->sgt)) { + err = PTR_ERR(priv->sgt); + dev_err(&indio_dev->dev, "Unable to map attachment: %d\n", err); + goto err_resv_unlock; + } + + kref_init(&priv->ref); + priv->buffer = buffer; + priv->attach = attach; + attach->importer_priv = priv; + + priv->block = buffer->access->attach_dmabuf(buffer, attach); + if (IS_ERR(priv->block)) { + err = PTR_ERR(priv->block); + goto err_dmabuf_unmap_attachment; + } + + dma_resv_unlock(dmabuf->resv); + + guard(mutex)(&buffer->dmabufs_mutex); + + /* + * Check whether we already have an attachment for this driver/DMABUF + * combo. If we do, refuse to attach. + */ + list_for_each_entry(each, &buffer->dmabufs, entry) { + if (each->attach->dev == indio_dev->dev.parent + && each->attach->dmabuf == dmabuf) { + /* + * We unlocked the reservation object, so going through + * the cleanup code would mean re-locking it first. + * At this stage it is simpler to free the attachment + * using iio_buffer_dma_put(). + */ + iio_buffer_dmabuf_put(attach); + return -EBUSY; + } + } + + /* Otherwise, add the new attachment to our dmabufs list. */ + list_add(&priv->entry, &buffer->dmabufs); + + return 0; + +err_dmabuf_unmap_attachment: + dma_buf_unmap_attachment(attach, priv->sgt, priv->dir); +err_resv_unlock: + dma_resv_unlock(dmabuf->resv); +err_dmabuf_detach: + dma_buf_detach(dmabuf, attach); +err_dmabuf_put: + dma_buf_put(dmabuf); +err_free_priv: + kfree(priv); + + return err; +} + +static int iio_buffer_detach_dmabuf(struct iio_dev_buffer_pair *ib, + int __user *user_req, bool nonblock) +{ + struct iio_buffer *buffer = ib->buffer; + struct iio_dev *indio_dev = ib->indio_dev; + struct iio_dmabuf_priv *priv; + struct dma_buf *dmabuf; + int dmabuf_fd, ret = -EPERM; + + if (copy_from_user(&dmabuf_fd, user_req, sizeof(dmabuf_fd))) + return -EFAULT; + + dmabuf = dma_buf_get(dmabuf_fd); + if (IS_ERR(dmabuf)) + return PTR_ERR(dmabuf); + + guard(mutex)(&buffer->dmabufs_mutex); + + list_for_each_entry(priv, &buffer->dmabufs, entry) { + if (priv->attach->dev == indio_dev->dev.parent + && priv->attach->dmabuf == dmabuf) { + list_del(&priv->entry); + + /* Unref the reference from iio_buffer_attach_dmabuf() */ + iio_buffer_dmabuf_put(priv->attach); + ret = 0; + break; + } + } + + dma_buf_put(dmabuf); + + return ret; +} + +static const char * +iio_buffer_dma_fence_get_driver_name(struct dma_fence *fence) +{ + return "iio"; +} + +static void iio_buffer_dma_fence_release(struct dma_fence *fence) +{ + struct iio_dma_fence *iio_fence = + container_of(fence, struct iio_dma_fence, base); + + kfree(iio_fence); +} + +static const struct dma_fence_ops iio_buffer_dma_fence_ops = { + .get_driver_name = iio_buffer_dma_fence_get_driver_name, + .get_timeline_name = iio_buffer_dma_fence_get_driver_name, + .release = iio_buffer_dma_fence_release, +}; + +static int iio_buffer_enqueue_dmabuf(struct iio_dev_buffer_pair *ib, + struct iio_dmabuf __user *iio_dmabuf_req, + bool nonblock) +{ + struct iio_buffer *buffer = ib->buffer; + struct iio_dmabuf iio_dmabuf; + struct dma_buf_attachment *attach; + struct iio_dmabuf_priv *priv; + struct iio_dma_fence *fence; + struct dma_buf *dmabuf; + unsigned long timeout; + bool cookie, cyclic, dma_to_ram; + long retl; + u32 seqno; + int ret; + + if (copy_from_user(&iio_dmabuf, iio_dmabuf_req, sizeof(iio_dmabuf))) + return -EFAULT; + + if (iio_dmabuf.flags & ~IIO_BUFFER_DMABUF_SUPPORTED_FLAGS) + return -EINVAL; + + cyclic = iio_dmabuf.flags & IIO_BUFFER_DMABUF_CYCLIC; + + /* Cyclic flag is only supported on output buffers */ + if (cyclic && buffer->direction != IIO_BUFFER_DIRECTION_OUT) + return -EINVAL; + + dmabuf = dma_buf_get(iio_dmabuf.fd); + if (IS_ERR(dmabuf)) + return PTR_ERR(dmabuf); + + if (!iio_dmabuf.bytes_used || iio_dmabuf.bytes_used > dmabuf->size) { + ret = -EINVAL; + goto err_dmabuf_put; + } + + attach = iio_buffer_find_attachment(ib, dmabuf, nonblock); + if (IS_ERR(attach)) { + ret = PTR_ERR(attach); + goto err_dmabuf_put; + } + + priv = attach->importer_priv; + + fence = kmalloc(sizeof(*fence), GFP_KERNEL); + if (!fence) { + ret = -ENOMEM; + goto err_attachment_put; + } + + fence->priv = priv; + + seqno = atomic_add_return(1, &priv->seqno); + + /* + * The transfers are guaranteed to be processed in the order they are + * enqueued, so we can use a simple incrementing sequence number for + * the dma_fence. + */ + dma_fence_init(&fence->base, &iio_buffer_dma_fence_ops, + &priv->lock, priv->context, seqno); + + ret = iio_dma_resv_lock(dmabuf, nonblock); + if (ret) + goto err_fence_put; + + timeout = nonblock ? 0 : msecs_to_jiffies(DMABUF_ENQUEUE_TIMEOUT_MS); + dma_to_ram = buffer->direction == IIO_BUFFER_DIRECTION_IN; + + /* Make sure we don't have writers */ + retl = dma_resv_wait_timeout(dmabuf->resv, + dma_resv_usage_rw(dma_to_ram), + true, timeout); + if (retl == 0) + retl = -EBUSY; + if (retl < 0) { + ret = (int)retl; + goto err_resv_unlock; + } + + if (buffer->access->lock_queue) + buffer->access->lock_queue(buffer); + + ret = dma_resv_reserve_fences(dmabuf->resv, 1); + if (ret) + goto err_queue_unlock; + + dma_resv_add_fence(dmabuf->resv, &fence->base, + dma_to_ram ? DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ); + dma_resv_unlock(dmabuf->resv); + + cookie = dma_fence_begin_signalling(); + + ret = buffer->access->enqueue_dmabuf(buffer, priv->block, &fence->base, + priv->sgt, iio_dmabuf.bytes_used, + cyclic); + if (ret) { + /* + * DMABUF enqueue failed, but we already added the fence. + * Signal the error through the fence completion mechanism. + */ + iio_buffer_signal_dmabuf_done(&fence->base, ret); + } + + if (buffer->access->unlock_queue) + buffer->access->unlock_queue(buffer); + + dma_fence_end_signalling(cookie); + dma_buf_put(dmabuf); + + return ret; + +err_queue_unlock: + if (buffer->access->unlock_queue) + buffer->access->unlock_queue(buffer); +err_resv_unlock: + dma_resv_unlock(dmabuf->resv); +err_fence_put: + dma_fence_put(&fence->base); +err_attachment_put: + iio_buffer_dmabuf_put(attach); +err_dmabuf_put: + dma_buf_put(dmabuf); + + return ret; +} + +static void iio_buffer_cleanup(struct work_struct *work) +{ + struct iio_dma_fence *fence = + container_of(work, struct iio_dma_fence, work); + struct iio_dmabuf_priv *priv = fence->priv; + struct dma_buf_attachment *attach = priv->attach; + + dma_fence_put(&fence->base); + iio_buffer_dmabuf_put(attach); +} + +void iio_buffer_signal_dmabuf_done(struct dma_fence *fence, int ret) +{ + struct iio_dma_fence *iio_fence = + container_of(fence, struct iio_dma_fence, base); + bool cookie = dma_fence_begin_signalling(); + + /* + * Get a reference to the fence, so that it's not freed as soon as + * it's signaled. + */ + dma_fence_get(fence); + + fence->error = ret; + dma_fence_signal(fence); + dma_fence_end_signalling(cookie); + + /* + * The fence will be unref'd in iio_buffer_cleanup. + * It can't be done here, as the unref functions might try to lock the + * resv object, which can deadlock. + */ + INIT_WORK(&iio_fence->work, iio_buffer_cleanup); + schedule_work(&iio_fence->work); +} +EXPORT_SYMBOL_GPL(iio_buffer_signal_dmabuf_done); + +static long iio_buffer_chrdev_ioctl(struct file *filp, + unsigned int cmd, unsigned long arg) +{ + struct iio_dev_buffer_pair *ib = filp->private_data; + void __user *_arg = (void __user *)arg; + bool nonblock = filp->f_flags & O_NONBLOCK; + + switch (cmd) { + case IIO_BUFFER_DMABUF_ATTACH_IOCTL: + return iio_buffer_attach_dmabuf(ib, _arg, nonblock); + case IIO_BUFFER_DMABUF_DETACH_IOCTL: + return iio_buffer_detach_dmabuf(ib, _arg, nonblock); + case IIO_BUFFER_DMABUF_ENQUEUE_IOCTL: + return iio_buffer_enqueue_dmabuf(ib, _arg, nonblock); + default: + return -EINVAL; + } +} + static const struct file_operations iio_buffer_chrdev_fileops = { .owner = THIS_MODULE, .llseek = noop_llseek, .read = iio_buffer_read, .write = iio_buffer_write, + .unlocked_ioctl = iio_buffer_chrdev_ioctl, + .compat_ioctl = compat_ptr_ioctl, .poll = iio_buffer_poll, .release = iio_buffer_chrdev_release, }; @@ -1994,6 +2450,7 @@ static void iio_buffer_release(struct kref *ref) { struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
+ mutex_destroy(&buffer->dmabufs_mutex); buffer->access->release(buffer); }
diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h index 89c3fd7c29ca..e72552e026f3 100644 --- a/include/linux/iio/buffer_impl.h +++ b/include/linux/iio/buffer_impl.h @@ -9,8 +9,12 @@ #include <uapi/linux/iio/buffer.h> #include <linux/iio/buffer.h>
+struct dma_buf_attachment; +struct dma_fence; struct iio_dev; +struct iio_dma_buffer_block; struct iio_buffer; +struct sg_table;
/** * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be @@ -39,6 +43,16 @@ struct iio_buffer; * device stops sampling. Calles are balanced with @enable. * @release: called when the last reference to the buffer is dropped, * should free all resources allocated by the buffer. + * @attach_dmabuf: called from userspace via ioctl to attach one external + * DMABUF. + * @detach_dmabuf: called from userspace via ioctl to detach one previously + * attached DMABUF. + * @enqueue_dmabuf: called from userspace via ioctl to queue this DMABUF + * object to this buffer. Requires a valid DMABUF fd, that + * was previouly attached to this buffer. + * @lock_queue: called when the core needs to lock the buffer queue; + * it is used when enqueueing DMABUF objects. + * @unlock_queue: used to unlock a previously locked buffer queue * @modes: Supported operating modes by this buffer type * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* * @@ -68,6 +82,17 @@ struct iio_buffer_access_funcs {
void (*release)(struct iio_buffer *buffer);
+ struct iio_dma_buffer_block * (*attach_dmabuf)(struct iio_buffer *buffer, + struct dma_buf_attachment *attach); + void (*detach_dmabuf)(struct iio_buffer *buffer, + struct iio_dma_buffer_block *block); + int (*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 (*lock_queue)(struct iio_buffer *buffer); + void (*unlock_queue)(struct iio_buffer *buffer); + unsigned int modes; unsigned int flags; }; @@ -136,6 +161,12 @@ struct iio_buffer {
/* @ref: Reference count of the buffer. */ struct kref ref; + + /* @dmabufs: List of DMABUF attachments */ + struct list_head dmabufs; /* P: dmabufs_mutex */ + + /* @dmabufs_mutex: Protects dmabufs */ + struct mutex dmabufs_mutex; };
/** @@ -159,6 +190,8 @@ void iio_buffer_init(struct iio_buffer *buffer); struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); void iio_buffer_put(struct iio_buffer *buffer);
+void iio_buffer_signal_dmabuf_done(struct dma_fence *fence, int ret); + #else /* CONFIG_IIO_BUFFER */
static inline void iio_buffer_get(struct iio_buffer *buffer) {} diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h index 13939032b3f6..c666aa95e532 100644 --- a/include/uapi/linux/iio/buffer.h +++ b/include/uapi/linux/iio/buffer.h @@ -5,6 +5,28 @@ #ifndef _UAPI_IIO_BUFFER_H_ #define _UAPI_IIO_BUFFER_H_
+#include <linux/types.h> + +/* Flags for iio_dmabuf.flags */ +#define IIO_BUFFER_DMABUF_CYCLIC (1 << 0) +#define IIO_BUFFER_DMABUF_SUPPORTED_FLAGS 0x00000001 + +/** + * struct iio_dmabuf - Descriptor for a single IIO DMABUF object + * @fd: file descriptor of the DMABUF object + * @flags: one or more IIO_BUFFER_DMABUF_* flags + * @bytes_used: number of bytes used in this DMABUF for the data transfer. + * Should generally be set to the DMABUF's size. + */ +struct iio_dmabuf { + __u32 fd; + __u32 flags; + __u64 bytes_used; +}; + #define IIO_BUFFER_GET_FD_IOCTL _IOWR('i', 0x91, int) +#define IIO_BUFFER_DMABUF_ATTACH_IOCTL _IOW('i', 0x92, int) +#define IIO_BUFFER_DMABUF_DETACH_IOCTL _IOW('i', 0x93, int) +#define IIO_BUFFER_DMABUF_ENQUEUE_IOCTL _IOW('i', 0x94, struct iio_dmabuf)
#endif /* _UAPI_IIO_BUFFER_H_ */
Hi Paul,
kernel test robot noticed the following build errors:
[auto build test ERROR on jic23-iio/togreg] [also build test ERROR on vkoul-dmaengine/next linus/master v6.10-rc4 next-20240618] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Paul-Cercueil/dmaengine-Add-A... base: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg patch link: https://lore.kernel.org/r/20240618100302.72886-4-paul%40crapouillou.net patch subject: [PATCH v11 3/7] iio: core: Add new DMABUF interface infrastructure config: x86_64-randconfig-161-20240619 (https://download.01.org/0day-ci/archive/20240619/202406191014.9JAzwRV6-lkp@i...) compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240619/202406191014.9JAzwRV6-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202406191014.9JAzwRV6-lkp@intel.com/
All errors (new ones prefixed by >>):
drivers/iio/industrialio-buffer.c:1715:3: error: cannot jump from this goto statement to its label
1715 | goto err_dmabuf_unmap_attachment; | ^ drivers/iio/industrialio-buffer.c:1720:2: note: jump bypasses initialization of variable with __attribute__((cleanup)) 1720 | guard(mutex)(&buffer->dmabufs_mutex); | ^ include/linux/cleanup.h:164:15: note: expanded from macro 'guard' 164 | CLASS(_name, __UNIQUE_ID(guard)) | ^ include/linux/compiler.h:189:29: note: expanded from macro '__UNIQUE_ID' 189 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | ^ include/linux/compiler_types.h:84:22: note: expanded from macro '__PASTE' 84 | #define __PASTE(a,b) ___PASTE(a,b) | ^ include/linux/compiler_types.h:83:23: note: expanded from macro '___PASTE' 83 | #define ___PASTE(a,b) a##b | ^ <scratch space>:126:1: note: expanded from here 126 | __UNIQUE_ID_guard696 | ^ drivers/iio/industrialio-buffer.c:1704:3: error: cannot jump from this goto statement to its label 1704 | goto err_resv_unlock; | ^ drivers/iio/industrialio-buffer.c:1720:2: note: jump bypasses initialization of variable with __attribute__((cleanup)) 1720 | guard(mutex)(&buffer->dmabufs_mutex); | ^ include/linux/cleanup.h:164:15: note: expanded from macro 'guard' 164 | CLASS(_name, __UNIQUE_ID(guard)) | ^ include/linux/compiler.h:189:29: note: expanded from macro '__UNIQUE_ID' 189 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | ^ include/linux/compiler_types.h:84:22: note: expanded from macro '__PASTE' 84 | #define __PASTE(a,b) ___PASTE(a,b) | ^ include/linux/compiler_types.h:83:23: note: expanded from macro '___PASTE' 83 | #define ___PASTE(a,b) a##b | ^ <scratch space>:126:1: note: expanded from here 126 | __UNIQUE_ID_guard696 | ^ drivers/iio/industrialio-buffer.c:1695:3: error: cannot jump from this goto statement to its label 1695 | goto err_dmabuf_detach; | ^ drivers/iio/industrialio-buffer.c:1720:2: note: jump bypasses initialization of variable with __attribute__((cleanup)) 1720 | guard(mutex)(&buffer->dmabufs_mutex); | ^ include/linux/cleanup.h:164:15: note: expanded from macro 'guard' 164 | CLASS(_name, __UNIQUE_ID(guard)) | ^ include/linux/compiler.h:189:29: note: expanded from macro '__UNIQUE_ID' 189 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | ^ include/linux/compiler_types.h:84:22: note: expanded from macro '__PASTE' 84 | #define __PASTE(a,b) ___PASTE(a,b) | ^ include/linux/compiler_types.h:83:23: note: expanded from macro '___PASTE' 83 | #define ___PASTE(a,b) a##b | ^ <scratch space>:126:1: note: expanded from here 126 | __UNIQUE_ID_guard696 | ^ drivers/iio/industrialio-buffer.c:1690:3: error: cannot jump from this goto statement to its label 1690 | goto err_dmabuf_put; | ^ drivers/iio/industrialio-buffer.c:1720:2: note: jump bypasses initialization of variable with __attribute__((cleanup)) 1720 | guard(mutex)(&buffer->dmabufs_mutex); | ^ include/linux/cleanup.h:164:15: note: expanded from macro 'guard' 164 | CLASS(_name, __UNIQUE_ID(guard)) | ^ include/linux/compiler.h:189:29: note: expanded from macro '__UNIQUE_ID' 189 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | ^ include/linux/compiler_types.h:84:22: note: expanded from macro '__PASTE' 84 | #define __PASTE(a,b) ___PASTE(a,b) | ^ include/linux/compiler_types.h:83:23: note: expanded from macro '___PASTE' 83 | #define ___PASTE(a,b) a##b | ^ <scratch space>:126:1: note: expanded from here 126 | __UNIQUE_ID_guard696 | ^ drivers/iio/industrialio-buffer.c:1684:3: error: cannot jump from this goto statement to its label 1684 | goto err_free_priv; | ^ drivers/iio/industrialio-buffer.c:1720:2: note: jump bypasses initialization of variable with __attribute__((cleanup)) 1720 | guard(mutex)(&buffer->dmabufs_mutex); | ^ include/linux/cleanup.h:164:15: note: expanded from macro 'guard' 164 | CLASS(_name, __UNIQUE_ID(guard)) | ^ include/linux/compiler.h:189:29: note: expanded from macro '__UNIQUE_ID' 189 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | ^ include/linux/compiler_types.h:84:22: note: expanded from macro '__PASTE' 84 | #define __PASTE(a,b) ___PASTE(a,b) | ^ include/linux/compiler_types.h:83:23: note: expanded from macro '___PASTE' 83 | #define ___PASTE(a,b) a##b
vim +1715 drivers/iio/industrialio-buffer.c
1655 1656 static int iio_buffer_attach_dmabuf(struct iio_dev_buffer_pair *ib, 1657 int __user *user_fd, bool nonblock) 1658 { 1659 struct iio_dev *indio_dev = ib->indio_dev; 1660 struct iio_buffer *buffer = ib->buffer; 1661 struct dma_buf_attachment *attach; 1662 struct iio_dmabuf_priv *priv, *each; 1663 struct dma_buf *dmabuf; 1664 int err, fd; 1665 1666 if (!buffer->access->attach_dmabuf 1667 || !buffer->access->detach_dmabuf 1668 || !buffer->access->enqueue_dmabuf) 1669 return -EPERM; 1670 1671 if (copy_from_user(&fd, user_fd, sizeof(fd))) 1672 return -EFAULT; 1673 1674 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 1675 if (!priv) 1676 return -ENOMEM; 1677 1678 spin_lock_init(&priv->lock); 1679 priv->context = dma_fence_context_alloc(1); 1680 1681 dmabuf = dma_buf_get(fd); 1682 if (IS_ERR(dmabuf)) { 1683 err = PTR_ERR(dmabuf); 1684 goto err_free_priv; 1685 } 1686 1687 attach = dma_buf_attach(dmabuf, indio_dev->dev.parent); 1688 if (IS_ERR(attach)) { 1689 err = PTR_ERR(attach); 1690 goto err_dmabuf_put; 1691 } 1692 1693 err = iio_dma_resv_lock(dmabuf, nonblock); 1694 if (err) 1695 goto err_dmabuf_detach; 1696 1697 priv->dir = buffer->direction == IIO_BUFFER_DIRECTION_IN 1698 ? DMA_FROM_DEVICE : DMA_TO_DEVICE; 1699 1700 priv->sgt = dma_buf_map_attachment(attach, priv->dir); 1701 if (IS_ERR(priv->sgt)) { 1702 err = PTR_ERR(priv->sgt); 1703 dev_err(&indio_dev->dev, "Unable to map attachment: %d\n", err); 1704 goto err_resv_unlock; 1705 } 1706 1707 kref_init(&priv->ref); 1708 priv->buffer = buffer; 1709 priv->attach = attach; 1710 attach->importer_priv = priv; 1711 1712 priv->block = buffer->access->attach_dmabuf(buffer, attach); 1713 if (IS_ERR(priv->block)) { 1714 err = PTR_ERR(priv->block);
1715 goto err_dmabuf_unmap_attachment;
1716 } 1717 1718 dma_resv_unlock(dmabuf->resv); 1719 1720 guard(mutex)(&buffer->dmabufs_mutex); 1721 1722 /* 1723 * Check whether we already have an attachment for this driver/DMABUF 1724 * combo. If we do, refuse to attach. 1725 */ 1726 list_for_each_entry(each, &buffer->dmabufs, entry) { 1727 if (each->attach->dev == indio_dev->dev.parent 1728 && each->attach->dmabuf == dmabuf) { 1729 /* 1730 * We unlocked the reservation object, so going through 1731 * the cleanup code would mean re-locking it first. 1732 * At this stage it is simpler to free the attachment 1733 * using iio_buffer_dma_put(). 1734 */ 1735 iio_buffer_dmabuf_put(attach); 1736 return -EBUSY; 1737 } 1738 } 1739 1740 /* Otherwise, add the new attachment to our dmabufs list. */ 1741 list_add(&priv->entry, &buffer->dmabufs); 1742 1743 return 0; 1744 1745 err_dmabuf_unmap_attachment: 1746 dma_buf_unmap_attachment(attach, priv->sgt, priv->dir); 1747 err_resv_unlock: 1748 dma_resv_unlock(dmabuf->resv); 1749 err_dmabuf_detach: 1750 dma_buf_detach(dmabuf, attach); 1751 err_dmabuf_put: 1752 dma_buf_put(dmabuf); 1753 err_free_priv: 1754 kfree(priv); 1755 1756 return err; 1757 } 1758
On Wed, 2024-06-19 at 11:15 +0800, kernel test robot wrote:
Hi Paul,
kernel test robot noticed the following build errors:
[auto build test ERROR on jic23-iio/togreg] [also build test ERROR on vkoul-dmaengine/next linus/master v6.10-rc4 next- 20240618] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Paul-Cercueil/dmaengine-Add-A... base: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git%C2%A0togreg patch link: https://lore.kernel.org/r/20240618100302.72886-4-paul%40crapouillou.net patch subject: [PATCH v11 3/7] iio: core: Add new DMABUF interface infrastructure config: x86_64-randconfig-161-20240619 (https://download.01.org/0day-ci/archive/20240619/202406191014.9JAzwRV6-lkp@i... om/config) compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project%C2%A0617a15a9eac96088ae5e9134248d8236e3...) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240619/202406191014.9JAzwRV6-lkp@i... om/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202406191014.9JAzwRV6-lkp@intel.com/
All errors (new ones prefixed by >>):
drivers/iio/industrialio-buffer.c:1715:3: error: cannot jump from this goto statement to its label
1715 | goto err_dmabuf_unmap_attachment; | ^ drivers/iio/industrialio-buffer.c:1720:2: note: jump bypasses initialization of
I guess the compiler produces code that will run the cleanup function on an uninitialized variable. I would then go back to plain mutex() instead of moving guard() to a place where it does not make sense only to shut up the warnings.
- Nuno Sá
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 Co-developed-by: Nuno Sa nuno.sa@analog.com 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.
v11: - Remove useless field "attach" in struct iio_dma_buffer_block - Document "sg_table" and "fence" fields in struct iio_block_state --- drivers/iio/buffer/industrialio-buffer-dma.c | 178 +++++++++++++++++-- include/linux/iio/buffer-dma.h | 31 ++++ 2 files changed, 198 insertions(+), 11 deletions(-)
diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index 13b1a858969e..647f417a045e 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; }
@@ -218,13 +233,20 @@ 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); iio_dma_buffer_queue_wake(queue); + dma_fence_end_signalling(cookie); } EXPORT_SYMBOL_GPL(iio_dma_buffer_block_done);
@@ -243,17 +265,27 @@ 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; + iio_dma_buffer_queue_wake(queue); + dma_fence_end_signalling(cookie); } EXPORT_SYMBOL_GPL(iio_dma_buffer_block_list_abort);
@@ -273,6 +305,16 @@ 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 @@ -299,6 +341,12 @@ 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; @@ -339,7 +387,7 @@ 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; @@ -412,8 +460,12 @@ 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 @@ -646,6 +698,110 @@ size_t iio_dma_buffer_usage(struct iio_buffer *buf) } EXPORT_SYMBOL_GPL(iio_dma_buffer_usage);
+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); + + /* 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 6e27e47077d5..5eb66a399002 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 +45,10 @@ 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 + * @sg_table: DMA table for the transfer when transferring a DMABUF + * @fence: DMA fence to be signaled when a DMABUF transfer is complete */ struct iio_dma_buffer_block { /* May only be accessed by the owner of the block */ @@ -63,6 +71,12 @@ 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 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; }; @@ -144,4 +162,17 @@ 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
Use the functions provided by the buffer-dma core to implement the DMABUF userspace API in the buffer-dmaengine IIO buffer implementation.
Since we want to be able to transfer an arbitrary number of bytes and not necesarily the full DMABUF, the associated scatterlist is converted to an array of DMA addresses + lengths, which is then passed to dmaengine_prep_slave_dma_array().
Signed-off-by: Paul Cercueil paul@crapouillou.net Co-developed-by: Nuno Sa nuno.sa@analog.com Signed-off-by: Nuno Sa nuno.sa@analog.com
--- v3: Use the new dmaengine_prep_slave_dma_array(), and adapt the code to work with the new functions introduced in industrialio-buffer-dma.c.
v5: - Use the new dmaengine_prep_slave_dma_vec(). - Restrict to input buffers, since output buffers are not yet supported by IIO buffers.
v6: - Populate .lock_queue / .unlock_queue callbacks - Switch to atomic memory allocations in .submit_queue, because of the dma_fence critical section - Make sure that the size of the scatterlist is enough
v7: Adapted patch for the changes made in patch 1.
v10: - Remove extra flags parameter to dmaengine_prep_peripheral_dma_vec() - Add support for TX transfers --- .../buffer/industrialio-buffer-dmaengine.c | 62 ++++++++++++++++--- 1 file changed, 53 insertions(+), 9 deletions(-)
diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c index 918f6f8d65b6..12aa1412dfa0 100644 --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c @@ -65,25 +65,62 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue, iio_buffer_to_dmaengine_buffer(&queue->buffer); struct dma_async_tx_descriptor *desc; enum dma_transfer_direction dma_dir; + struct scatterlist *sgl; + struct dma_vec *vecs; size_t max_size; dma_cookie_t cookie; + size_t len_total; + unsigned int i; + int nents;
max_size = min(block->size, dmaengine_buffer->max_size); max_size = round_down(max_size, dmaengine_buffer->align);
- if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) { - block->bytes_used = max_size; + if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) dma_dir = DMA_DEV_TO_MEM; - } else { + else dma_dir = DMA_MEM_TO_DEV; - }
- if (!block->bytes_used || block->bytes_used > max_size) - return -EINVAL; + if (block->sg_table) { + sgl = block->sg_table->sgl; + nents = sg_nents_for_len(sgl, block->bytes_used); + if (nents < 0) + return nents; + + vecs = kmalloc_array(nents, sizeof(*vecs), GFP_ATOMIC); + if (!vecs) + return -ENOMEM; + + len_total = block->bytes_used; + + for (i = 0; i < nents; i++) { + vecs[i].addr = sg_dma_address(sgl); + vecs[i].len = min(sg_dma_len(sgl), len_total); + len_total -= vecs[i].len; + + sgl = sg_next(sgl); + }
- desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, - block->phys_addr, block->bytes_used, dma_dir, - DMA_PREP_INTERRUPT); + desc = dmaengine_prep_peripheral_dma_vec(dmaengine_buffer->chan, + vecs, nents, dma_dir, + DMA_PREP_INTERRUPT); + kfree(vecs); + } else { + max_size = min(block->size, dmaengine_buffer->max_size); + max_size = round_down(max_size, dmaengine_buffer->align); + + if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) + block->bytes_used = max_size; + + if (!block->bytes_used || block->bytes_used > max_size) + return -EINVAL; + + desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, + block->phys_addr, + block->bytes_used, + dma_dir, + DMA_PREP_INTERRUPT); + } if (!desc) return -ENOMEM;
@@ -133,6 +170,13 @@ static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = { .space_available = iio_dma_buffer_usage, .release = iio_dmaengine_buffer_release,
+ .enqueue_dmabuf = iio_dma_buffer_enqueue_dmabuf, + .attach_dmabuf = iio_dma_buffer_attach_dmabuf, + .detach_dmabuf = iio_dma_buffer_detach_dmabuf, + + .lock_queue = iio_dma_buffer_lock_queue, + .unlock_queue = iio_dma_buffer_unlock_queue, + .modes = INDIO_BUFFER_HARDWARE, .flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK, };
Document the new DMABUF based API.
Signed-off-by: Paul Cercueil paul@crapouillou.net Co-developed-by: Nuno Sa nuno.sa@analog.com Signed-off-by: Nuno Sa nuno.sa@analog.com
--- v2: - Explicitly state that the new interface is optional and is not implemented by all drivers. - The IOCTLs can now only be called on the buffer FD returned by IIO_BUFFER_GET_FD_IOCTL. - Move the page up a bit in the index since it is core stuff and not driver-specific.
v3: Update the documentation to reflect the new API.
v5: Use description lists for the documentation of the three new IOCTLs instead of abusing subsections.
v8: Renamed dmabuf_api.rst -> iio_dmabuf_api.rst, and updated index.rst whose format changed in iio/togreg.
v11: - "a IIO buffer" -> "an IIO buffer" - Add variable name in IOCTL calls --- Documentation/iio/iio_dmabuf_api.rst | 54 ++++++++++++++++++++++++++++ Documentation/iio/index.rst | 1 + 2 files changed, 55 insertions(+) create mode 100644 Documentation/iio/iio_dmabuf_api.rst
diff --git a/Documentation/iio/iio_dmabuf_api.rst b/Documentation/iio/iio_dmabuf_api.rst new file mode 100644 index 000000000000..ad0177c3fef2 --- /dev/null +++ b/Documentation/iio/iio_dmabuf_api.rst @@ -0,0 +1,54 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================================== +High-speed DMABUF interface for IIO +=================================== + +1. Overview +=========== + +The Industrial I/O subsystem supports access to buffers through a +file-based interface, with read() and write() access calls through the +IIO device's dev node. + +It additionally supports a DMABUF based interface, where the userspace +can attach DMABUF objects (externally created) to an IIO buffer, and +subsequently use them for data transfers. + +A userspace application can then use this interface to share DMABUF +objects between several interfaces, allowing it to transfer data in a +zero-copy fashion, for instance between IIO and the USB stack. + +The userspace application can also memory-map the DMABUF objects, and +access the sample data directly. The advantage of doing this vs. the +read() interface is that it avoids an extra copy of the data between the +kernel and userspace. This is particularly useful for high-speed devices +which produce several megabytes or even gigabytes of data per second. +It does however increase the userspace-kernelspace synchronization +overhead, as the DMA_BUF_SYNC_START and DMA_BUF_SYNC_END IOCTLs have to +be used for data integrity. + +2. User API +=========== + +As part of this interface, three new IOCTLs have been added. These three +IOCTLs have to be performed on the IIO buffer's file descriptor, +obtained using the IIO_BUFFER_GET_FD_IOCTL() ioctl. + + ``IIO_BUFFER_DMABUF_ATTACH_IOCTL(int fd)`` + Attach the DMABUF object, identified by its file descriptor, to the + IIO buffer. Returns zero on success, and a negative errno value on + error. + + ``IIO_BUFFER_DMABUF_DETACH_IOCTL(int fd)`` + Detach the given DMABUF object, identified by its file descriptor, + from the IIO buffer. Returns zero on success, and a negative errno + value on error. + + Note that closing the IIO buffer's file descriptor will + automatically detach all previously attached DMABUF objects. + + ``IIO_BUFFER_DMABUF_ENQUEUE_IOCTL(struct iio_dmabuf *iio_dmabuf)`` + Enqueue a previously attached DMABUF object to the buffer queue. + Enqueued DMABUFs will be read from (if output buffer) or written to + (if input buffer) as long as the buffer is enabled. diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst index 4c13bfa2865c..9cb4c50cb20d 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -9,6 +9,7 @@ Industrial I/O
iio_configfs iio_devbuf + iio_dmabuf_api iio_tools
Industrial I/O Kernel Drivers
On Tue, Jun 18, 2024 at 12:03:01PM +0200, Paul Cercueil wrote:
+As part of this interface, three new IOCTLs have been added. These three +IOCTLs have to be performed on the IIO buffer's file descriptor, +obtained using the IIO_BUFFER_GET_FD_IOCTL() ioctl.
"... which can be obtained using ..."
Document the dmaengine_prep_peripheral_dma_vec() API function, the device_prep_peripheral_dma_vec() backend function, and the dma_vec struct.
Signed-off-by: Paul Cercueil paul@crapouillou.net
--- v11: New patch --- Documentation/driver-api/dmaengine/client.rst | 9 +++++++++ Documentation/driver-api/dmaengine/provider.rst | 10 ++++++++++ 2 files changed, 19 insertions(+)
diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst index ecf139f73da4..d491e385d61a 100644 --- a/Documentation/driver-api/dmaengine/client.rst +++ b/Documentation/driver-api/dmaengine/client.rst @@ -80,6 +80,10 @@ The details of these operations are:
- slave_sg: DMA a list of scatter gather buffers from/to a peripheral
+ - peripheral_dma_vec: DMA an array of scatter gather buffers from/to a + peripheral. Similar to slave_sg, but uses an array of dma_vec + structures instead of a scatterlist. + - dma_cyclic: Perform a cyclic DMA operation from/to a peripheral till the operation is explicitly stopped.
@@ -102,6 +106,11 @@ The details of these operations are: unsigned int sg_len, enum dma_data_direction direction, unsigned long flags);
+ struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec( + struct dma_chan *chan, const struct dma_vec *vecs, + size_t nents, enum dma_data_direction direction, + unsigned long flags); + struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic( struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len, size_t period_len, enum dma_data_direction direction); diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index ceac2a300e32..3085f8b460fa 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -433,6 +433,12 @@ supported. - residue: Provides the residue bytes of the transfer for those that support residue.
+- ``device_prep_peripheral_dma_vec`` + + - Similar to ``device_prep_slave_sg``, but it takes a pointer to a + array of ``dma_vec`` structures, which (in the long run) will replace + scatterlists. + - ``device_issue_pending``
- Takes the first transaction descriptor in the pending queue, @@ -544,6 +550,10 @@ dma_cookie_t - Not really relevant any more since the introduction of ``virt-dma`` that abstracts it away.
+dma_vec + +- A small structure that contains a DMA address and length. + DMA_CTRL_ACK
- If clear, the descriptor cannot be reused by provider until the
On Tue, Jun 18, 2024 at 12:03:02PM +0200, Paul Cercueil wrote:
Document the dmaengine_prep_peripheral_dma_vec() API function, the device_prep_peripheral_dma_vec() backend function, and the dma_vec struct.
LGTM, thanks!
Reviewed-by: Bagas Sanjaya bagasdotme@gmail.com
linaro-mm-sig@lists.linaro.org
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Bagas Sanjaya -
kernel test robot -
Nuno Sá -
Paul Cercueil