From patchwork Tue Dec 19 17:50:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498759 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 507993B78E; Tue, 19 Dec 2023 17:50:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="MD7vMUMC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008218; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mefUUY4PY+5zEqdnyMwjckQ6lxyQfK8RCtgZJoFSsZA=; b=MD7vMUMC4oPmjYBQEv5bIQAzFYYL4b9CV6xWxXvAkBxCrHvfJJsOT2a6KLYYVE57uZ7lP5 fe9LxGyopxojuYwQ732mr9+TTP72e+ZzX2oeEjWnjoia0RiSBypWGtlhwBamgIlX+IkKrb I6KJv4FcSUA2mHJo7BsHK5ZX1myVTh8= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 1/8] iio: buffer-dma: Get rid of outgoing queue Date: Tue, 19 Dec 2023 18:50:02 +0100 Message-ID: <20231219175009.65482-2-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes The buffer-dma code was using two queues, incoming and outgoing, to manage the state of the blocks in use. While this totally works, it adds some complexity to the code, especially since the code only manages 2 blocks. It is much easier to just check each block's state manually, and keep a counter for the next block to dequeue. Since the new DMABUF based API wouldn't use the outgoing queue anyway, getting rid of it now makes the upcoming changes simpler. With this change, the IIO_BLOCK_STATE_DEQUEUED is now useless, and can be removed. Signed-off-by: Paul Cercueil --- v2: - Only remove the outgoing queue, and keep the incoming queue, as we want the buffer to start streaming data as soon as it is enabled. - Remove IIO_BLOCK_STATE_DEQUEUED, since it is now functionally the same as IIO_BLOCK_STATE_DONE. --- drivers/iio/buffer/industrialio-buffer-dma.c | 44 ++++++++++---------- include/linux/iio/buffer-dma.h | 7 ++-- 2 files changed, 26 insertions(+), 25 deletions(-) diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index d348af8b9705..1fc91467d1aa 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -179,7 +179,7 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( } block->size = size; - block->state = IIO_BLOCK_STATE_DEQUEUED; + block->state = IIO_BLOCK_STATE_DONE; block->queue = queue; INIT_LIST_HEAD(&block->head); kref_init(&block->kref); @@ -191,16 +191,8 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) { - struct iio_dma_buffer_queue *queue = block->queue; - - /* - * The buffer has already been freed by the application, just drop the - * reference. - */ - if (block->state != IIO_BLOCK_STATE_DEAD) { + if (block->state != IIO_BLOCK_STATE_DEAD) block->state = IIO_BLOCK_STATE_DONE; - list_add_tail(&block->head, &queue->outgoing); - } } /** @@ -261,7 +253,6 @@ static bool iio_dma_block_reusable(struct iio_dma_buffer_block *block) * not support abort and has not given back the block yet. */ switch (block->state) { - case IIO_BLOCK_STATE_DEQUEUED: case IIO_BLOCK_STATE_QUEUED: case IIO_BLOCK_STATE_DONE: return true; @@ -317,7 +308,6 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) * dead. This means we can reset the lists without having to fear * corrution. */ - INIT_LIST_HEAD(&queue->outgoing); spin_unlock_irq(&queue->list_lock); INIT_LIST_HEAD(&queue->incoming); @@ -456,14 +446,20 @@ static struct iio_dma_buffer_block *iio_dma_buffer_dequeue( struct iio_dma_buffer_queue *queue) { struct iio_dma_buffer_block *block; + unsigned int idx; spin_lock_irq(&queue->list_lock); - block = list_first_entry_or_null(&queue->outgoing, struct - iio_dma_buffer_block, head); - if (block != NULL) { - list_del(&block->head); - block->state = IIO_BLOCK_STATE_DEQUEUED; + + idx = queue->fileio.next_dequeue; + block = queue->fileio.blocks[idx]; + + if (block->state == IIO_BLOCK_STATE_DONE) { + idx = (idx + 1) % ARRAY_SIZE(queue->fileio.blocks); + queue->fileio.next_dequeue = idx; + } else { + block = NULL; } + spin_unlock_irq(&queue->list_lock); return block; @@ -539,6 +535,7 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buf); struct iio_dma_buffer_block *block; size_t data_available = 0; + unsigned int i; /* * For counting the available bytes we'll use the size of the block not @@ -552,8 +549,15 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) data_available += queue->fileio.active_block->size; spin_lock_irq(&queue->list_lock); - list_for_each_entry(block, &queue->outgoing, head) - data_available += block->size; + + for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { + block = queue->fileio.blocks[i]; + + if (block != queue->fileio.active_block + && block->state == IIO_BLOCK_STATE_DONE) + data_available += block->size; + } + spin_unlock_irq(&queue->list_lock); mutex_unlock(&queue->lock); @@ -617,7 +621,6 @@ int iio_dma_buffer_init(struct iio_dma_buffer_queue *queue, queue->ops = ops; INIT_LIST_HEAD(&queue->incoming); - INIT_LIST_HEAD(&queue->outgoing); mutex_init(&queue->lock); spin_lock_init(&queue->list_lock); @@ -645,7 +648,6 @@ void iio_dma_buffer_exit(struct iio_dma_buffer_queue *queue) continue; queue->fileio.blocks[i]->state = IIO_BLOCK_STATE_DEAD; } - INIT_LIST_HEAD(&queue->outgoing); spin_unlock_irq(&queue->list_lock); INIT_LIST_HEAD(&queue->incoming); diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index 6564bdcdac66..18d3702fa95d 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -19,14 +19,12 @@ struct device; /** * enum iio_block_state - State of a struct iio_dma_buffer_block - * @IIO_BLOCK_STATE_DEQUEUED: Block is not queued * @IIO_BLOCK_STATE_QUEUED: Block is on the incoming queue * @IIO_BLOCK_STATE_ACTIVE: Block is currently being processed by the DMA * @IIO_BLOCK_STATE_DONE: Block is on the outgoing queue * @IIO_BLOCK_STATE_DEAD: Block has been marked as to be freed */ enum iio_block_state { - IIO_BLOCK_STATE_DEQUEUED, IIO_BLOCK_STATE_QUEUED, IIO_BLOCK_STATE_ACTIVE, IIO_BLOCK_STATE_DONE, @@ -73,12 +71,15 @@ struct iio_dma_buffer_block { * @active_block: Block being used in read() * @pos: Read offset in the active block * @block_size: Size of each block + * @next_dequeue: index of next block that will be dequeued */ struct iio_dma_buffer_queue_fileio { struct iio_dma_buffer_block *blocks[2]; struct iio_dma_buffer_block *active_block; size_t pos; size_t block_size; + + unsigned int next_dequeue; }; /** @@ -93,7 +94,6 @@ struct iio_dma_buffer_queue_fileio { * list and typically also a list of active blocks in the part that handles * the DMA controller * @incoming: List of buffers on the incoming queue - * @outgoing: List of buffers on the outgoing queue * @active: Whether the buffer is currently active * @fileio: FileIO state */ @@ -105,7 +105,6 @@ struct iio_dma_buffer_queue { struct mutex lock; spinlock_t list_lock; struct list_head incoming; - struct list_head outgoing; bool active; From patchwork Tue Dec 19 17:50:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498760 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F215039846; Tue, 19 Dec 2023 17:50:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="MuLGfssg" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008220; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oGRsJ+tJFINsq/9OPmu94IJFWwVMC9QjYHPIQeMCNU4=; b=MuLGfssg4c9uqlHRE79Zan0YaFSA3PIM61XIkgjxelhw2LYPW8Jn5pJTAmN0n8UE/9AEV0 I6LySUbuJkX7pS6REh3X6KUQauCdJbZajVCIWXQ3CmRo01P3enWEBItJwTkaJO7etrVqF7 H6+2m5ML39bNO7JhosPuSzW5yinBUbo= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Alexandru Ardelean , Alexandru Ardelean , Paul Cercueil Subject: [PATCH v5 2/8] iio: buffer-dma: split iio_dma_buffer_fileio_free() function Date: Tue, 19 Dec 2023 18:50:03 +0100 Message-ID: <20231219175009.65482-3-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes From: Alexandru Ardelean This change splits the logic into a separate function, which will be re-used later. Signed-off-by: Alexandru Ardelean Cc: Alexandru Ardelean Signed-off-by: Paul Cercueil --- drivers/iio/buffer/industrialio-buffer-dma.c | 43 +++++++++++--------- 1 file changed, 24 insertions(+), 19 deletions(-) diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index 1fc91467d1aa..5610ba67925e 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -346,6 +346,29 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) } EXPORT_SYMBOL_GPL(iio_dma_buffer_request_update); +static void iio_dma_buffer_fileio_free(struct iio_dma_buffer_queue *queue) +{ + unsigned int i; + + spin_lock_irq(&queue->list_lock); + for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { + if (!queue->fileio.blocks[i]) + continue; + queue->fileio.blocks[i]->state = IIO_BLOCK_STATE_DEAD; + } + spin_unlock_irq(&queue->list_lock); + + INIT_LIST_HEAD(&queue->incoming); + + for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { + if (!queue->fileio.blocks[i]) + continue; + iio_buffer_block_put(queue->fileio.blocks[i]); + queue->fileio.blocks[i] = NULL; + } + queue->fileio.active_block = NULL; +} + static void iio_dma_buffer_submit_block(struct iio_dma_buffer_queue *queue, struct iio_dma_buffer_block *block) { @@ -638,27 +661,9 @@ EXPORT_SYMBOL_GPL(iio_dma_buffer_init); */ void iio_dma_buffer_exit(struct iio_dma_buffer_queue *queue) { - unsigned int i; - mutex_lock(&queue->lock); - spin_lock_irq(&queue->list_lock); - for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { - if (!queue->fileio.blocks[i]) - continue; - queue->fileio.blocks[i]->state = IIO_BLOCK_STATE_DEAD; - } - spin_unlock_irq(&queue->list_lock); - - INIT_LIST_HEAD(&queue->incoming); - - for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { - if (!queue->fileio.blocks[i]) - continue; - iio_buffer_block_put(queue->fileio.blocks[i]); - queue->fileio.blocks[i] = NULL; - } - queue->fileio.active_block = NULL; + iio_dma_buffer_fileio_free(queue); queue->ops = NULL; mutex_unlock(&queue->lock); From patchwork Tue Dec 19 17:50:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498761 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E7F3E3B78E; Tue, 19 Dec 2023 17:50:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="UP5c1Sxc" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008221; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ciNLk5XaUXAioykenKcf7E1KkXSWDnIcRp3Oxutuxu0=; b=UP5c1Sxcxd0EHUS1lhLee/aLiy44BhJinhMdEny4JnaaZrz/16ZQVxyFmmzX5VFb9P/3UV neuPGHc3Zp/6kG6dyhc1/ryGu89tDkHCiLorkOwyJQIX/6Vrz/0mVcdrdI/uOJbyqMWvcG Y/ZC881VtK7MJ25/041T5ofdpUJRMuc= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 3/8] dmaengine: Add API function dmaengine_prep_slave_dma_vec() Date: Tue, 19 Dec 2023 18:50:04 +0100 Message-ID: <20231219175009.65482-4-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes 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 --- 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? --- include/linux/dmaengine.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 3df70d6131c8..ee5931ddb42f 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_slave_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, @@ -972,6 +986,17 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( dir, flags, NULL); } +static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_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_slave_dma_vec) + return NULL; + + return chan->device->device_prep_slave_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) From patchwork Tue Dec 19 17:50:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498762 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB28D41C89; Tue, 19 Dec 2023 17:50:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="qWWR0Z7q" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008222; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AixFPBmj0sGmUeQqUl8x5UZmHCNRunKymgdO2FCRupY=; b=qWWR0Z7qkmRWWymGyFIo/XJHgX93Knhnb6x7GekZLkk6eJQizJJmBXilQb6b6wrPs8t+2e /G+WTm6qRjjc01LibcFoqkI8tErybF7UjG6VN5cbkdXp41/lQUn1K3pO7Z2HFQL6+8RP6y ZXeQXJEE7D5Ui63jg4NT+A//fyfv3Ks= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 4/8] dmaengine: dma-axi-dmac: Implement device_prep_slave_dma_vec Date: Tue, 19 Dec 2023 18:50:05 +0100 Message-ID: <20231219175009.65482-5-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes Add implementation of the .device_prep_slave_dma_vec() callback. Signed-off-by: Paul Cercueil --- v3: New patch v5: Implement .device_prep_slave_dma_vec() instead of v3's .device_prep_slave_dma_array(). --- 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 2457a420c13d..363808088cc5 100644 --- a/drivers/dma/dma-axi-dmac.c +++ b/drivers/dma/dma-axi-dmac.c @@ -535,6 +535,45 @@ 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_slave_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(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, @@ -957,6 +996,7 @@ 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_slave_dma_vec = axi_dmac_prep_slave_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; From patchwork Tue Dec 19 17:50:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498763 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7341942054; Tue, 19 Dec 2023 17:51:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="pXQivTgW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008223; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YYehNBgT3gl7Aub1xHBJlvTB7ei9jO5KY2L6XcmlaP4=; b=pXQivTgWp46MYo89Y87zWo2NeOjSvY4hatDwM5yCoV4CKYJnOdZUMpH5dgUEOA93A9Qh8P qbTA359k57KsfMeoOSkdlaBmEslCgWVdj8ai1r3CBDRfsypp4opL6dlKTTeXIcZ90pFc6H qk0UAinhcz5ivLdevJLw021xR9/V6TQ= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 5/8] iio: core: Add new DMABUF interface infrastructure Date: Tue, 19 Dec 2023 18:50:06 +0100 Message-ID: <20231219175009.65482-6-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes 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 --- 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 --- drivers/iio/industrialio-buffer.c | 402 ++++++++++++++++++++++++++++++ include/linux/iio/buffer_impl.h | 26 ++ include/uapi/linux/iio/buffer.h | 22 ++ 3 files changed, 450 insertions(+) diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 09c41e9ccf87..24c040e073a7 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -13,10 +13,14 @@ #include #include #include +#include +#include +#include #include #include #include #include +#include #include #include @@ -28,6 +32,31 @@ #include #include +#define DMABUF_ENQUEUE_TIMEOUT_MS 5000 + +struct iio_dma_fence; + +struct iio_dmabuf_priv { + struct list_head entry; + struct kref ref; + + struct iio_buffer *buffer; + struct iio_dma_buffer_block *block; + + u64 context; + spinlock_t lock; + + struct dma_buf_attachment *attach; + struct iio_dma_fence *fence; +}; + +struct iio_dma_fence { + struct dma_fence base; + struct iio_dmabuf_priv *priv; + struct sg_table *sgt; + enum dma_data_direction dir; +}; + static const char * const iio_endian_prefix[] = { [IIO_BE] = "be", [IIO_LE] = "le", @@ -332,6 +361,7 @@ 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); init_waitqueue_head(&buffer->pollq); kref_init(&buffer->ref); if (!buffer->watermark) @@ -1519,14 +1549,54 @@ 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; + + buffer->access->detach_dmabuf(buffer, priv->block); + + dma_buf_detach(attach->dmabuf, attach); + dma_buf_put(dmabuf); + kfree(priv); +} + +void iio_buffer_dmabuf_get(struct dma_buf_attachment *attach) +{ + struct iio_dmabuf_priv *priv = attach->importer_priv; + + kref_get(&priv->ref); +} +EXPORT_SYMBOL_GPL(iio_buffer_dmabuf_get); + +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); +} +EXPORT_SYMBOL_GPL(iio_buffer_dmabuf_put); + 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); + /* 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); + } + + if (!list_empty(&buffer->dmabufs)) + dev_warn(&indio_dev->dev, "Buffer FD closed with active transfers\n"); + kfree(ib); clear_bit(IIO_BUSY_BIT_POS, &buffer->flags); iio_device_put(indio_dev); @@ -1534,11 +1604,343 @@ 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) +{ + int ret; + + ret = dma_resv_lock_interruptible(dmabuf->resv, NULL); + if (ret) { + if (ret != -EDEADLK) + goto out; + if (nonblock) { + ret = -EBUSY; + goto out; + } + + ret = dma_resv_lock_slow_interruptible(dmabuf->resv, NULL); + } + +out: + return ret; +} + +static struct dma_buf_attachment * +iio_buffer_find_attachment(struct iio_dev *indio_dev, struct dma_buf *dmabuf) +{ + struct dma_buf_attachment *elm, *attach = NULL; + int ret; + + ret = iio_dma_resv_lock(dmabuf, false); + if (ret) + return ERR_PTR(ret); + + list_for_each_entry(elm, &dmabuf->attachments, node) { + if (elm->dev == indio_dev->dev.parent) { + attach = elm; + break; + } + } + + if (attach) + iio_buffer_dmabuf_get(elm); + + dma_resv_unlock(dmabuf->resv); + + return attach ?: ERR_PTR(-EPERM); +} + +static int iio_buffer_attach_dmabuf(struct iio_dev_buffer_pair *ib, + int __user *user_fd) +{ + struct iio_dev *indio_dev = ib->indio_dev; + struct iio_buffer *buffer = ib->buffer; + struct dma_buf_attachment *attach; + struct iio_dmabuf_priv *priv; + 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; + } + + 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_detach; + } + + list_add(&priv->entry, &buffer->dmabufs); + + return 0; + +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_req) +{ + struct dma_buf_attachment *attach; + struct iio_dmabuf_priv *priv; + struct dma_buf *dmabuf; + int dmabuf_fd, ret = 0; + + 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); + + attach = iio_buffer_find_attachment(ib->indio_dev, dmabuf); + if (IS_ERR(attach)) { + ret = PTR_ERR(attach); + goto out_dmabuf_put; + } + + priv = attach->importer_priv; + list_del_init(&priv->entry); + + /* + * Unref twice to release the reference obtained with + * iio_buffer_find_attachment() above, and the one obtained in + * iio_buffer_attach_dmabuf(). + */ + iio_buffer_dmabuf_put(attach); + iio_buffer_dmabuf_put(attach); + +out_dmabuf_put: + 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_dev *indio_dev = ib->indio_dev; + struct iio_buffer *buffer = ib->buffer; + struct iio_dmabuf iio_dmabuf; + struct dma_buf_attachment *attach; + struct iio_dmabuf_priv *priv; + enum dma_data_direction dir; + struct iio_dma_fence *fence; + struct dma_buf *dmabuf; + struct sg_table *sgt; + unsigned long timeout; + bool dma_to_ram; + bool cyclic; + 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(indio_dev, dmabuf); + if (IS_ERR(attach)) { + ret = PTR_ERR(attach); + goto err_dmabuf_put; + } + + priv = attach->importer_priv; + + dma_to_ram = buffer->direction == IIO_BUFFER_DIRECTION_IN; + dir = dma_to_ram ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + sgt = dma_buf_map_attachment(attach, dir); + if (IS_ERR(sgt)) { + ret = PTR_ERR(sgt); + dev_err(&indio_dev->dev, "Unable to map attachment: %d\n", ret); + goto err_attachment_put; + } + + fence = kmalloc(sizeof(*fence), GFP_KERNEL); + if (!fence) { + ret = -ENOMEM; + goto err_unmap_attachment; + } + + fence->priv = priv; + fence->sgt = sgt; + fence->dir = dir; + priv->fence = fence; + + dma_fence_init(&fence->base, &iio_buffer_dma_fence_ops, + &priv->lock, priv->context, 0); + + ret = iio_dma_resv_lock(dmabuf, nonblock); + if (ret) + goto err_fence_put; + + timeout = nonblock ? 0 : msecs_to_jiffies(DMABUF_ENQUEUE_TIMEOUT_MS); + + /* Make sure we don't have writers */ + ret = (int) dma_resv_wait_timeout(dmabuf->resv, DMA_RESV_USAGE_WRITE, + true, timeout); + if (ret == 0) + ret = -EBUSY; + if (ret < 0) + goto err_resv_unlock; + + if (dma_to_ram) { + /* + * If we're writing to the DMABUF, make sure we don't have + * readers + */ + ret = (int) dma_resv_wait_timeout(dmabuf->resv, + DMA_RESV_USAGE_READ, true, + timeout); + if (ret == 0) + ret = -EBUSY; + if (ret < 0) + goto err_resv_unlock; + } + + ret = dma_resv_reserve_fences(dmabuf->resv, 1); + if (ret) + goto err_resv_unlock; + + dma_resv_add_fence(dmabuf->resv, &fence->base, + dma_resv_usage_rw(dma_to_ram)); + dma_resv_unlock(dmabuf->resv); + + ret = buffer->access->enqueue_dmabuf(buffer, priv->block, sgt, + iio_dmabuf.bytes_used, cyclic); + if (ret) + iio_buffer_signal_dmabuf_done(attach, ret); + + dma_buf_put(dmabuf); + + return ret; + +err_resv_unlock: + dma_resv_unlock(dmabuf->resv); +err_fence_put: + dma_fence_put(&fence->base); +err_unmap_attachment: + dma_buf_unmap_attachment(attach, sgt, dir); +err_attachment_put: + iio_buffer_dmabuf_put(attach); +err_dmabuf_put: + dma_buf_put(dmabuf); + + return ret; +} + +void iio_buffer_signal_dmabuf_done(struct dma_buf_attachment *attach, int ret) +{ + struct iio_dmabuf_priv *priv = attach->importer_priv; + struct iio_dma_fence *fence = priv->fence; + enum dma_data_direction dir = fence->dir; + struct sg_table *sgt = fence->sgt; + + dma_fence_get(&fence->base); + fence->base.error = ret; + dma_fence_signal(&fence->base); + dma_fence_put(&fence->base); + + dma_buf_unmap_attachment(attach, sgt, dir); + iio_buffer_dmabuf_put(attach); +} +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; + + switch (cmd) { + case IIO_BUFFER_DMABUF_ATTACH_IOCTL: + return iio_buffer_attach_dmabuf(ib, _arg); + case IIO_BUFFER_DMABUF_DETACH_IOCTL: + return iio_buffer_detach_dmabuf(ib, _arg); + case IIO_BUFFER_DMABUF_ENQUEUE_IOCTL: + return iio_buffer_enqueue_dmabuf(ib, _arg, + filp->f_flags & O_NONBLOCK); + default: + return IIO_IOCTL_UNHANDLED; + } +} + 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, }; diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h index 89c3fd7c29ca..55d93705c96b 100644 --- a/include/linux/iio/buffer_impl.h +++ b/include/linux/iio/buffer_impl.h @@ -9,8 +9,11 @@ #include #include +struct dma_buf_attachment; 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 +42,13 @@ 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. * @modes: Supported operating modes by this buffer type * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* * @@ -68,6 +78,14 @@ 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 sg_table *sgt, size_t size, bool cyclic); + unsigned int modes; unsigned int flags; }; @@ -136,6 +154,9 @@ struct iio_buffer { /* @ref: Reference count of the buffer. */ struct kref ref; + + /* @dmabufs: List of DMABUF attachments */ + struct list_head dmabufs; }; /** @@ -156,9 +177,14 @@ int iio_update_buffers(struct iio_dev *indio_dev, **/ void iio_buffer_init(struct iio_buffer *buffer); +void iio_buffer_dmabuf_get(struct dma_buf_attachment *attach); +void iio_buffer_dmabuf_put(struct dma_buf_attachment *attach); + 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_buf_attachment *attach, 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 + +/* 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_ */ From patchwork Tue Dec 19 17:50:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498764 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D712B4205C; Tue, 19 Dec 2023 17:51:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="p7h2ER0g" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008224; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DNw3I5HuhPmlnSXVtXDqFLfSyXkJfOclGbXyvWeX0aw=; b=p7h2ER0g3sFi1FRrn8xOF6ETiu5PhECvzoHooHsdjit/PzlDOueEUEovrFIx1ql1uhLy2j J0055zuN0fwt8n9Q7g55uBzXyKvPDpL3HrhfDxxl0vnaqnjDYGODsId6l0+RAStlEp8hSV f7PzQ7tp0RrZ95BROutPtrDJUyMEhi4= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 6/8] iio: buffer-dma: Enable support for DMABUFs Date: Tue, 19 Dec 2023 18:50:07 +0100 Message-ID: <20231219175009.65482-7-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes 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 --- v3: Update code to provide the functions that will be used as callbacks for the new IOCTLs. --- drivers/iio/buffer/industrialio-buffer-dma.c | 157 +++++++++++++++++-- include/linux/iio/buffer-dma.h | 26 +++ 2 files changed, 170 insertions(+), 13 deletions(-) diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index 5610ba67925e..adb64f975064 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -94,14 +95,24 @@ 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); + mutex_lock(&queue->lock); - iio_buffer_put(&block->queue->buffer); + if (block->fileio) { + dma_free_coherent(queue->dev, PAGE_ALIGN(block->size), + block->vaddr, block->phys_addr); + queue->num_fileio_blocks--; + } + + queue->num_blocks--; kfree(block); + + mutex_unlock(&queue->lock); + + iio_buffer_put(&queue->buffer); } static void iio_buffer_block_get(struct iio_dma_buffer_block *block) @@ -163,7 +174,7 @@ 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 +182,16 @@ 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 +200,9 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( iio_buffer_get(&queue->buffer); + queue->num_blocks++; + queue->num_fileio_blocks += fileio; + return block; } @@ -211,6 +228,9 @@ 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); + if (!block->fileio) + iio_buffer_signal_dmabuf_done(block->attach, 0); + iio_buffer_block_put_atomic(block); wake_up_interruptible_poll(&queue->buffer.pollq, EPOLLIN | EPOLLRDNORM); } @@ -237,10 +257,14 @@ 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); + + if (!block->fileio) + iio_buffer_signal_dmabuf_done(block->attach, -EINTR); iio_buffer_block_put_atomic(block); } spin_unlock_irqrestore(&queue->list_lock, flags); + queue->fileio.enabled = false; wake_up_interruptible_poll(&queue->buffer.pollq, EPOLLIN | EPOLLRDNORM); } EXPORT_SYMBOL_GPL(iio_dma_buffer_block_list_abort); @@ -261,6 +285,12 @@ static bool iio_dma_block_reusable(struct iio_dma_buffer_block *block) } } +static bool iio_dma_buffer_fileio_mode(struct iio_dma_buffer_queue *queue) +{ + return queue->fileio.enabled || + queue->num_blocks == queue->num_fileio_blocks; +} + /** * iio_dma_buffer_request_update() - DMA buffer request_update callback * @buffer: The buffer which to request an update @@ -287,6 +317,12 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) mutex_lock(&queue->lock); + queue->fileio.enabled = iio_dma_buffer_fileio_mode(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; @@ -317,7 +353,7 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) block = queue->fileio.blocks[i]; if (block->state == IIO_BLOCK_STATE_DEAD) { /* Could not reuse it */ - iio_buffer_block_put(block); + iio_buffer_block_put_atomic(block); block = NULL; } else { block->size = size; @@ -327,7 +363,7 @@ 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; @@ -363,7 +399,7 @@ static void iio_dma_buffer_fileio_free(struct iio_dma_buffer_queue *queue) for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) { if (!queue->fileio.blocks[i]) continue; - iio_buffer_block_put(queue->fileio.blocks[i]); + iio_buffer_block_put_atomic(queue->fileio.blocks[i]); queue->fileio.blocks[i] = NULL; } queue->fileio.active_block = NULL; @@ -384,8 +420,12 @@ 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->attach, 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 +628,97 @@ 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; + int err; + + mutex_lock(&queue->lock); + + /* + * If the buffer is enabled and in fileio mode new blocks can't be + * allocated. + */ + if (queue->fileio.enabled) { + err = -EBUSY; + goto err_unlock; + } + + block = iio_dma_buffer_alloc_block(queue, attach->dmabuf->size, false); + if (!block) { + err = -ENOMEM; + goto err_unlock; + } + + block->attach = attach; + + /* Free memory that might be in use for fileio mode */ + iio_dma_buffer_fileio_free(queue); + + mutex_unlock(&queue->lock); + + return block; + +err_unlock: + mutex_unlock(&queue->lock); + return ERR_PTR(err); +} +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_DONE: + return 0; + default: + return -EBUSY; + } +} + +int iio_dma_buffer_enqueue_dmabuf(struct iio_buffer *buffer, + struct iio_dma_buffer_block *block, + struct sg_table *sgt, + size_t size, bool cyclic) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + int ret = 0; + + mutex_lock(&queue->lock); + ret = iio_dma_can_enqueue_block(block); + if (ret < 0) + goto out_mutex_unlock; + + block->bytes_used = size; + block->cyclic = cyclic; + block->sg_table = sgt; + + iio_dma_buffer_enqueue(queue, block); + +out_mutex_unlock: + mutex_unlock(&queue->lock); + return ret; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_enqueue_dmabuf); + /** * 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..7be12a6bff5b 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -16,6 +16,8 @@ struct iio_dma_buffer_queue; struct iio_dma_buffer_ops; struct device; +struct dma_buf_attachment; +struct sg_table; /** * enum iio_block_state - State of a struct iio_dma_buffer_block @@ -41,6 +43,8 @@ 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 +67,12 @@ 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 dma_buf_attachment *attach; + struct sg_table *sg_table; }; /** @@ -72,6 +82,7 @@ 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 +91,7 @@ struct iio_dma_buffer_queue_fileio { size_t block_size; unsigned int next_dequeue; + bool enabled; }; /** @@ -95,6 +107,8 @@ 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_blocks: Total number of DMA blocks + * @num_fileio_blocks: Number of DMA blocks for fileio mode * @fileio: FileIO state */ struct iio_dma_buffer_queue { @@ -107,6 +121,8 @@ struct iio_dma_buffer_queue { struct list_head incoming; bool active; + unsigned int num_blocks; + unsigned int num_fileio_blocks; struct iio_dma_buffer_queue_fileio fileio; }; @@ -142,4 +158,14 @@ 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 sg_table *sgt, + size_t size, bool cyclic); + #endif From patchwork Tue Dec 19 17:50:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498765 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2FFB45C17; Tue, 19 Dec 2023 17:51:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="lfVWCHwS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008225; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=e7fwZsaolFkOpPsDd74Ly10WkyLo2LNDxuxjwogSFJQ=; b=lfVWCHwSm37pIKUzOiE/NipNnaf+A+cN3rzXZWZVGJsgPu61ei5HWDEnxhfB+CB7eOyKwK CThUjG0QBJDE4KjA3pVK9aifL/tG4UaK8vV6PcZRx8k0gKU2HrbmKrVNeQmiODaCxWlJ99 EwLiV9FNjlmbB/f7jHrj0G/4nm4FwcI= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 7/8] iio: buffer-dmaengine: Support new DMABUF based userspace API Date: Tue, 19 Dec 2023 18:50:08 +0100 Message-ID: <20231219175009.65482-8-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes 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 --- 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. --- .../buffer/industrialio-buffer-dmaengine.c | 52 ++++++++++++++++--- 1 file changed, 46 insertions(+), 6 deletions(-) diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c index 5f85ba38e6f6..825d76a24a67 100644 --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c @@ -64,15 +64,51 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue, struct dmaengine_buffer *dmaengine_buffer = iio_buffer_to_dmaengine_buffer(&queue->buffer); struct dma_async_tx_descriptor *desc; + unsigned int i, nents; + struct scatterlist *sgl; + struct dma_vec *vecs; + size_t max_size; dma_cookie_t cookie; + size_t len_total; - block->bytes_used = min(block->size, dmaengine_buffer->max_size); - block->bytes_used = round_down(block->bytes_used, - dmaengine_buffer->align); + if (queue->buffer.direction != IIO_BUFFER_DIRECTION_IN) { + /* We do not yet support output buffers. */ + return -EINVAL; + } - desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, - block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM, - DMA_PREP_INTERRUPT); + if (block->sg_table) { + sgl = block->sg_table->sgl; + nents = sg_nents_for_len(sgl, block->bytes_used); + + vecs = kmalloc_array(nents, sizeof(*vecs), GFP_KERNEL); + 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_dma_vec(dmaengine_buffer->chan, + vecs, nents, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + kfree(vecs); + } else { + max_size = min(block->size, dmaengine_buffer->max_size); + max_size = round_down(max_size, dmaengine_buffer->align); + block->bytes_used = max_size; + + desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, + block->phys_addr, + block->bytes_used, + DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + } if (!desc) return -ENOMEM; @@ -120,6 +156,10 @@ static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = { .data_available = iio_dma_buffer_data_available, .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, + .modes = INDIO_BUFFER_HARDWARE, .flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK, }; From patchwork Tue Dec 19 17:50:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13498766 Received: from aposti.net (aposti.net [89.234.176.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AFC72498AB; Tue, 19 Dec 2023 17:51:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="J9fAlELL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1703008226; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6SosLHUfbvBusyQrjhEdH6qlujZTce4ql106/+fLWzw=; b=J9fAlELLwr4u9tQx12Md08M19jXx7ynqeRbwh2bn3D4jBBjrFqmsfNIv7OLIFcqqSLmdeN QC516M58Q7HMEZjPI/cYNl+yjV+mqFJMFElgpPlX/YGHL1beQenrhYuznSawwdxC2Tc7Iw FPKphSbHxxtpXJYnuOdVN8jzVvyOL/0= From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Vinod Koul , Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Nuno_S=C3=A1?= , Michael Hennerich , Paul Cercueil Subject: [PATCH v5 8/8] Documentation: iio: Document high-speed DMABUF based API Date: Tue, 19 Dec 2023 18:50:09 +0100 Message-ID: <20231219175009.65482-9-paul@crapouillou.net> In-Reply-To: <20231219175009.65482-1-paul@crapouillou.net> References: <20231219175009.65482-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam: Yes Document the new DMABUF based API. Signed-off-by: Paul Cercueil --- 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. --- Documentation/iio/dmabuf_api.rst | 54 ++++++++++++++++++++++++++++++++ Documentation/iio/index.rst | 2 ++ 2 files changed, 56 insertions(+) create mode 100644 Documentation/iio/dmabuf_api.rst diff --git a/Documentation/iio/dmabuf_api.rst b/Documentation/iio/dmabuf_api.rst new file mode 100644 index 000000000000..1cd6cd51a582 --- /dev/null +++ b/Documentation/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 a 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)`` + 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)`` + 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 1b7292c58cd0..3eae8fcb1938 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -9,6 +9,8 @@ Industrial I/O iio_configfs + dmabuf_api + ep93xx_adc bno055