From patchwork Mon Feb 15 14:32:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Ardelean X-Patchwork-Id: 12088309 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 822CAC433DB for ; Mon, 15 Feb 2021 14:31:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5329A64DEE for ; Mon, 15 Feb 2021 14:31:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229974AbhBOObU (ORCPT ); Mon, 15 Feb 2021 09:31:20 -0500 Received: from mx0a-00128a01.pphosted.com ([148.163.135.77]:38628 "EHLO mx0a-00128a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229802AbhBOObR (ORCPT ); Mon, 15 Feb 2021 09:31:17 -0500 Received: from pps.filterd (m0167089.ppops.net [127.0.0.1]) by mx0a-00128a01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 11FEK3FL032455; Mon, 15 Feb 2021 09:30:24 -0500 Received: from nwd2mta3.analog.com ([137.71.173.56]) by mx0a-00128a01.pphosted.com with ESMTP id 36pcjamssr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 15 Feb 2021 09:30:24 -0500 Received: from SCSQMBX11.ad.analog.com (SCSQMBX11.ad.analog.com [10.77.17.10]) by nwd2mta3.analog.com (8.14.7/8.14.7) with ESMTP id 11FEUMB1038347 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=FAIL); Mon, 15 Feb 2021 09:30:22 -0500 Received: from SCSQCASHYB7.ad.analog.com (10.77.17.133) by SCSQMBX11.ad.analog.com (10.77.17.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1779.2; Mon, 15 Feb 2021 06:30:21 -0800 Received: from SCSQMBX11.ad.analog.com (10.77.17.10) by SCSQCASHYB7.ad.analog.com (10.77.17.133) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.721.2; Mon, 15 Feb 2021 06:30:20 -0800 Received: from zeus.spd.analog.com (10.66.68.11) by SCSQMBX11.ad.analog.com (10.77.17.10) with Microsoft SMTP Server id 15.1.1779.2 via Frontend Transport; Mon, 15 Feb 2021 06:30:20 -0800 Received: from localhost.localdomain ([10.48.65.12]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 11FEUGbi027532; Mon, 15 Feb 2021 09:30:18 -0500 From: Alexandru Ardelean To: , CC: , , , , , Alexandru Ardelean Subject: [PATCH v3 1/5] iio: core: Add mmap interface infrastructure Date: Mon, 15 Feb 2021 16:32:30 +0200 Message-ID: <20210215143234.3248-2-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210215143234.3248-1-alexandru.ardelean@analog.com> References: <20210215143234.3248-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-15_08:2021-02-12,2021-02-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 spamscore=0 bulkscore=0 mlxscore=0 malwarescore=0 suspectscore=0 adultscore=0 clxscore=1015 phishscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102150116 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Lars-Peter Clausen Add the necessary infrastructure to the IIO core to support an mmap based interface to access the capture data. The advantage of the mmap based interface compared to the read() based interface is that it avoids an extra copy of the data between kernel and userspace. This is particular useful for high-speed devices which produce several megabytes or even gigabytes of data per second. The data for the mmap interface is managed at the granularity of so called blocks. A block is a contiguous region of memory (at the moment both physically and virtually contiguous). Reducing the granularity from byte level to block level is done to reduce the userspace-kernelspace synchronization overhead since performing syscalls for each byte at a data-rate of a few megabytes is not feasible. This of course leads to a slightly increased latency. For this reason an application can choose the size of the blocks as well as how many blocks it allocates. E.g. two blocks would be a traditional double buffering scheme. But using a higher number might be necessary to avoid underflow/overflow situations in the presence of scheduling latencies. A block can either be owned by kernel space or userspace. When owned by userspace it save to access the data in the block and process it. When owned by kernel space the block can be in one of 3 states. It can be in the incoming queue where all blocks submitted from userspace are placed and are waiting to be processed by the kernel driver. It can be currently being processed by the kernel driver, this means it is actively placing capturing data in it (usually using DMA). Or it can be in the outgoing queue where all blocks that have been processed by the kernel are placed. Userspace can dequeue the blocks as necessary. As part of the interface 5 new IOCTLs to manage the blocks and exchange them between userspace and kernelspace. The IOCTLs can be accessed through a open file descriptor to a IIO device. IIO_BUFFER_BLOCK_ALLOC_IOCTL(struct iio_buffer_block_alloc_req *): Allocates new blocks. Can be called multiple times if necessary. A newly allocated block is initially owned by userspace. IIO_BUFFER_BLOCK_FREE_IOCTL(void): Frees all previously allocated blocks. If the backing memory of a block is still in use by a kernel driver (i.e. active DMA transfer) it will be freed once the kernel driver has released it. IIO_BUFFER_BLOCK_QUERY_IOCTL(struct iio_buffer_block *): Queries information about a block. The id of the block about which information is to be queried needs to be set by userspace. IIO_BUFFER_BLOCK_ENQUEUE_IOCTL(struct iio_buffer_block *): Places a block on the incoming queue. This transfers ownership of the block from userspace to kernelspace. Userspace must populate the id field of the block to indicate which block to enqueue. IIO_BUFFER_BLOCK_DEQUEUE_IOCTL(struct iio_buffer_block *): Removes the first block from the outgoing queue. This transfers ownership of the block from kernelspace to userspace. Kernelspace will populate all fields of the block. If the queue is empty and the file descriptor is set to blocking the IOCTL will block until a new block is available on the outgoing queue. To access the data stored in a block by userspace the block must be mapped to the process's memory. This is done by calling mmap() on the IIO device file descriptor. Each block has a unique offset assigned to it which should be passed to the mmap interface. E.g. mmap(0, block.size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, block.offset); A typical workflow for the new interface is: BLOCK_ALLOC foreach block BLOCK_QUERY block mmap block.data.offset BLOCK_ENQUEUE block enable buffer while !done BLOCK_DEQUEUE block process data BLOCK_ENQUEUE block disable buffer BLOCK_FREE Signed-off-by: Lars-Peter Clausen Signed-off-by: Alexandru Ardelean --- drivers/iio/industrialio-buffer.c | 158 ++++++++++++++++++++++++++++++ include/linux/iio/buffer-dma.h | 5 - include/linux/iio/buffer_impl.h | 23 +++++ include/uapi/linux/iio/buffer.h | 44 +++++++++ 4 files changed, 225 insertions(+), 5 deletions(-) diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 4848932d4394..5d641f8adfbd 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -1371,6 +1372,12 @@ 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_free_blocks(struct iio_buffer *buffer) +{ + if (buffer->access->free_blocks) + buffer->access->free_blocks(buffer); +} + static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) { struct iio_dev_buffer_pair *ib = filep->private_data; @@ -1381,16 +1388,23 @@ static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) kfree(ib); clear_bit(IIO_BUSY_BIT_POS, &buffer->flags); + iio_buffer_free_blocks(buffer); iio_device_put(indio_dev); return 0; } +static long iio_buffer_ioctl(struct file *filep, unsigned int cmd, unsigned long arg); +static int iio_buffer_mmap(struct file *filep, struct vm_area_struct *vma); + static const struct file_operations iio_buffer_chrdev_fileops = { .owner = THIS_MODULE, .llseek = noop_llseek, .read = iio_buffer_read, .poll = iio_buffer_poll, + .unlocked_ioctl = iio_buffer_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .mmap = iio_buffer_mmap, .release = iio_buffer_chrdev_release, }; @@ -1768,6 +1782,150 @@ void iio_buffer_put(struct iio_buffer *buffer) } EXPORT_SYMBOL_GPL(iio_buffer_put); +static int iio_buffer_query_block(struct iio_buffer *buffer, + struct iio_buffer_block __user *user_block) +{ + struct iio_buffer_block block; + int ret; + + if (!buffer->access->query_block) + return -ENOSYS; + + if (copy_from_user(&block, user_block, sizeof(block))) + return -EFAULT; + + ret = buffer->access->query_block(buffer, &block); + if (ret) + return ret; + + if (copy_to_user(user_block, &block, sizeof(block))) + return -EFAULT; + + return 0; +} + +static int iio_buffer_dequeue_block(struct iio_dev *indio_dev, + struct iio_buffer *buffer, + struct iio_buffer_block __user *user_block, + bool non_blocking) +{ + struct iio_buffer_block block; + int ret; + + if (!buffer->access->dequeue_block) + return -ENOSYS; + + do { + if (!iio_buffer_data_available(buffer)) { + if (non_blocking) + return -EAGAIN; + + ret = wait_event_interruptible(buffer->pollq, + iio_buffer_data_available(buffer) || + indio_dev->info == NULL); + if (ret) + return ret; + if (indio_dev->info == NULL) + return -ENODEV; + } + + ret = buffer->access->dequeue_block(buffer, &block); + if (ret == -EAGAIN && non_blocking) + ret = 0; + } while (ret); + + if (ret) + return ret; + + if (copy_to_user(user_block, &block, sizeof(block))) + return -EFAULT; + + return 0; +} + +static int iio_buffer_enqueue_block(struct iio_buffer *buffer, + struct iio_buffer_block __user *user_block) +{ + struct iio_buffer_block block; + + if (!buffer->access->enqueue_block) + return -ENOSYS; + + if (copy_from_user(&block, user_block, sizeof(block))) + return -EFAULT; + + return buffer->access->enqueue_block(buffer, &block); +} + +static int iio_buffer_alloc_blocks(struct iio_buffer *buffer, + struct iio_buffer_block_alloc_req __user *user_req) +{ + struct iio_buffer_block_alloc_req req; + int ret; + + if (!buffer->access->alloc_blocks) + return -ENOSYS; + + if (copy_from_user(&req, user_req, sizeof(req))) + return -EFAULT; + + ret = buffer->access->alloc_blocks(buffer, &req); + if (ret) + return ret; + + if (copy_to_user(user_req, &req, sizeof(req))) + return -EFAULT; + + return 0; +} + +static long iio_buffer_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) +{ + bool non_blocking = filep->f_flags & O_NONBLOCK; + struct iio_dev_buffer_pair *ib = filep->private_data; + struct iio_dev *indio_dev = ib->indio_dev; + struct iio_buffer *buffer = ib->buffer; + + if (!buffer || !buffer->access) + return -ENODEV; + + switch (cmd) { + case IIO_BUFFER_BLOCK_ALLOC_IOCTL: + return iio_buffer_alloc_blocks(buffer, + (struct iio_buffer_block_alloc_req __user *)arg); + case IIO_BUFFER_BLOCK_FREE_IOCTL: + iio_buffer_free_blocks(buffer); + return 0; + case IIO_BUFFER_BLOCK_QUERY_IOCTL: + return iio_buffer_query_block(buffer, + (struct iio_buffer_block __user *)arg); + case IIO_BUFFER_BLOCK_ENQUEUE_IOCTL: + return iio_buffer_enqueue_block(buffer, + (struct iio_buffer_block __user *)arg); + case IIO_BUFFER_BLOCK_DEQUEUE_IOCTL: + return iio_buffer_dequeue_block(indio_dev, buffer, + (struct iio_buffer_block __user *)arg, non_blocking); + } + return -EINVAL; +} + +static int iio_buffer_mmap(struct file *filep, struct vm_area_struct *vma) +{ + struct iio_dev_buffer_pair *ib = filep->private_data; + struct iio_buffer *buffer = ib->buffer; + + if (!buffer->access || !buffer->access->mmap) + return -ENODEV; + + if (!(vma->vm_flags & VM_SHARED)) + return -EINVAL; + + if (!(vma->vm_flags & VM_READ)) + return -EINVAL; + + return buffer->access->mmap(buffer, vma); +} + /** * iio_device_attach_buffer - Attach a buffer to a IIO device * @indio_dev: The device the buffer should be attached to diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index ff15c61bf319..6564bdcdac66 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -17,11 +17,6 @@ struct iio_dma_buffer_queue; struct iio_dma_buffer_ops; struct device; -struct iio_buffer_block { - u32 size; - u32 bytes_used; -}; - /** * enum iio_block_state - State of a struct iio_dma_buffer_block * @IIO_BLOCK_STATE_DEQUEUED: Block is not queued diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h index 245b32918ae1..1d57dc7ccb4f 100644 --- a/include/linux/iio/buffer_impl.h +++ b/include/linux/iio/buffer_impl.h @@ -34,6 +34,18 @@ 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. + * @alloc_blocks: called from userspace via ioctl to allocate blocks + * that will be used via the mmap interface. + * @free_blocks: called from userspace via ioctl to free all blocks + * allocated for this buffer. + * @enqueue_block: called from userspace via ioctl to queue this block + * to this buffer. Requires a valid block id. + * @dequeue_block: called from userspace via ioctl to dequeue this block + * from this buffer. Requires a valid block id. + * @query_block: called from userspace via ioctl to query the attributes + * of this block. Requires a valid block id. + * @mmap: mmap hook for this buffer. Userspace mmap() calls will + * get routed to this. * @modes: Supported operating modes by this buffer type * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* * @@ -60,6 +72,17 @@ struct iio_buffer_access_funcs { void (*release)(struct iio_buffer *buffer); + int (*alloc_blocks)(struct iio_buffer *buffer, + struct iio_buffer_block_alloc_req *req); + int (*free_blocks)(struct iio_buffer *buffer); + int (*enqueue_block)(struct iio_buffer *buffer, + struct iio_buffer_block *block); + int (*dequeue_block)(struct iio_buffer *buffer, + struct iio_buffer_block *block); + int (*query_block)(struct iio_buffer *buffer, + struct iio_buffer_block *block); + int (*mmap)(struct iio_buffer *buffer, struct vm_area_struct *vma); + unsigned int modes; unsigned int flags; }; diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h index 13939032b3f6..8c1a2f27e5a2 100644 --- a/include/uapi/linux/iio/buffer.h +++ b/include/uapi/linux/iio/buffer.h @@ -5,6 +5,50 @@ #ifndef _UAPI_IIO_BUFFER_H_ #define _UAPI_IIO_BUFFER_H_ +/** + * struct iio_buffer_block_alloc_req - Descriptor for allocating IIO buffer blocks + * @type: type of block(s) to allocate (currently unused, reserved) + * @size: the size of a single block + * @count: the number of blocks to allocate + * @id: returned by the request, the number of blocks allocated + */ +struct iio_buffer_block_alloc_req { + __u32 type; + __u32 size; + __u32 count; + __u32 id; +}; + +/* A function will be assigned later for BIT(0) */ +#define IIO_BUFFER_BLOCK_FLAG_RESERVED (1 << 0) + +/** + * struct iio_buffer_block - Descriptor for a single IIO block + * @id: identifier of the block + * @size: size of the block + * @bytes_used: number of bytes used in this block by a data transfer + * @type: type of this block (currently unused, reserved) + * @flags: flags for this buffer, set when enqueuing this block + * @offset: data offset of this block in a larger memory segment + * @timestamp: timestamp for this block + */ +struct iio_buffer_block { + __u32 id; + __u32 size; + __u32 bytes_used; + __u32 type; + __u32 flags; + union { + __u32 offset; + } data; + __u64 timestamp; +}; + #define IIO_BUFFER_GET_FD_IOCTL _IOWR('i', 0x91, int) +#define IIO_BUFFER_BLOCK_ALLOC_IOCTL _IOWR('i', 0x92, struct iio_buffer_block_alloc_req) +#define IIO_BUFFER_BLOCK_FREE_IOCTL _IO('i', 0x93) +#define IIO_BUFFER_BLOCK_QUERY_IOCTL _IOWR('i', 0x93, struct iio_buffer_block) +#define IIO_BUFFER_BLOCK_ENQUEUE_IOCTL _IOWR('i', 0x94, struct iio_buffer_block) +#define IIO_BUFFER_BLOCK_DEQUEUE_IOCTL _IOWR('i', 0x95, struct iio_buffer_block) #endif /* _UAPI_IIO_BUFFER_H_ */ From patchwork Mon Feb 15 14:32:31 2021 Content-Type: text/plain; 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Mon, 15 Feb 2021 09:30:22 -0500 Received: from localhost.localdomain ([10.48.65.12]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 11FEUGbj027532; Mon, 15 Feb 2021 09:30:20 -0500 From: Alexandru Ardelean To: , CC: , , , , , Alexandru Ardelean Subject: [PATCH v3 2/5] Documentation: iio: add doc for high-speed buffer API Date: Mon, 15 Feb 2021 16:32:31 +0200 Message-ID: <20210215143234.3248-3-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210215143234.3248-1-alexandru.ardelean@analog.com> References: <20210215143234.3248-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-15_08:2021-02-12,2021-02-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 mlxlogscore=770 phishscore=0 clxscore=1015 mlxscore=0 priorityscore=1501 impostorscore=0 adultscore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102150117 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org This change takes the comment from the commit that introduces the IIO high-speed buffer API, and formats it into rst format. Signed-off-by: Alexandru Ardelean --- Documentation/iio/iio_high_speed_buffers.rst | 100 +++++++++++++++++++ Documentation/iio/index.rst | 2 + include/uapi/linux/iio/buffer.h | 5 + 3 files changed, 107 insertions(+) create mode 100644 Documentation/iio/iio_high_speed_buffers.rst diff --git a/Documentation/iio/iio_high_speed_buffers.rst b/Documentation/iio/iio_high_speed_buffers.rst new file mode 100644 index 000000000000..f326e68efe49 --- /dev/null +++ b/Documentation/iio/iio_high_speed_buffers.rst @@ -0,0 +1,100 @@ +=================================== +Industrial IO High-Speed Buffer API +=================================== + +1. Overview +=========== + +Industrial IO supports access to buffers via an mmap interface. The +advantage of the mmap based interface compared to the read() based +interface is that it avoids an extra copy of the data between kernel and +userspace. This is particular useful for high-speed devices which produce +several megabytes or even gigabytes of data per second. + +The data for the mmap interface is managed at the granularity of so called +blocks. A block is a contiguous region of memory (at the moment both +physically and virtually contiguous). Reducing the granularity from byte +level to block level is done to reduce the userspace-kernelspace +synchronization overhead since performing syscalls for each byte at a +data-rate of a few megabytes is not feasible. + +This of course leads to a slightly increased latency. For this reason an +application can choose the size of the blocks as well as how many blocks it +allocates. E.g. two blocks would be a traditional double buffering scheme. +But using a higher number might be necessary to avoid underflow/overflow +situations in the presence of scheduling latencies. + +A block can either be owned by kernel space or userspace. When owned by +userspace it is safe to access the data in the block and process it. When +owned by kernel space the block can be in one of 3 states: + +* It can be in the incoming queue where all blocks submitted from userspace + are placed and are waiting to be processed by the kernel driver. +* It can be currently being processed by the kernel driver, this means it is + actively placing capturing data in it (usually using DMA). +* Or it can be in the outgoing queue where all blocks that have been + processed by the kernel are placed. Userspace can dequeue the blocks as + necessary. + +2. Interface +============ + +As part of the interface 5 IOCTLs are used to manage the blocks and exchange +them between userspace and kernelspace. The IOCTLs can be accessed through +a open file descriptor to a IIO device. + +* **IIO_BUFFER_BLOCK_ALLOC_IOCTL(struct iio_buffer_block_alloc_req *)**: + Allocates new blocks. Can be called multiple times if necessary. A newly + allocated block is initially owned by userspace. + +* **IIO_BUFFER_BLOCK_FREE_IOCTL(void)**: + Frees all previously allocated blocks. If the backing memory of a block is + still in use by a kernel driver (i.e. active DMA transfer) it will be + freed once the kernel driver has released it. + +* **IIO_BUFFER_BLOCK_QUERY_IOCTL(struct iio_buffer_block *)**: + Queries information about a block. The id of the block about which + information is to be queried needs to be set by userspace. + +* **IIO_BUFFER_BLOCK_ENQUEUE_IOCTL(struct iio_buffer_block *)**: + Places a block on the incoming queue. This transfers ownership of the + block from userspace to kernelspace. Userspace must populate the id field + of the block to indicate which block to enqueue. + +* **IIO_BUFFER_BLOCK_DEQUEUE_IOCTL(struct iio_buffer_block *)**: + Removes the first block from the outgoing queue. This transfers ownership + of the block from kernelspace to userspace. Kernelspace will populate all + fields of the block. If the queue is empty and the file descriptor is set + to blocking the IOCTL will block until a new block is available on the + outgoing queue. + +3. Usage +======== + +To access the data stored in a block by userspace the block must be mapped +to the process's memory. This is done by calling mmap() on the IIO device +file descriptor. Each block has a unique offset assigned to it which should +be passed to the mmap interface. E.g. + + mmap(0, block.size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, + block.offset); + +A typical workflow for the new interface is: + + BLOCK_ALLOC + + foreach block + BLOCK_QUERY block + mmap block.data.offset + BLOCK_ENQUEUE block + + enable buffer + + while !done + BLOCK_DEQUEUE block + process data + BLOCK_ENQUEUE block + + disable buffer + + BLOCK_FREE diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst index 58b7a4ebac51..aaba78770b47 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -9,4 +9,6 @@ Industrial I/O iio_configfs + iio_high_speed_buffers + ep93xx_adc diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h index 8c1a2f27e5a2..d8c64210c9cc 100644 --- a/include/uapi/linux/iio/buffer.h +++ b/include/uapi/linux/iio/buffer.h @@ -5,6 +5,11 @@ #ifndef _UAPI_IIO_BUFFER_H_ #define _UAPI_IIO_BUFFER_H_ +/** + * See for more details: + * Documentation/iio/iio_high_speed_buffers.rst + */ + /** * struct iio_buffer_block_alloc_req - Descriptor for allocating IIO buffer blocks * @type: type of block(s) to allocate (currently unused, reserved) From patchwork Mon Feb 15 14:32:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Ardelean X-Patchwork-Id: 12088311 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10397C433E0 for ; Mon, 15 Feb 2021 14:31:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAECA614A5 for ; Mon, 15 Feb 2021 14:31:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229998AbhBOObU (ORCPT ); Mon, 15 Feb 2021 09:31:20 -0500 Received: from mx0a-00128a01.pphosted.com ([148.163.135.77]:42562 "EHLO mx0a-00128a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229910AbhBOObS (ORCPT ); Mon, 15 Feb 2021 09:31:18 -0500 Received: from pps.filterd (m0167088.ppops.net [127.0.0.1]) by mx0a-00128a01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 11FEU6H6025770; Mon, 15 Feb 2021 09:30:26 -0500 Received: from nwd2mta4.analog.com ([137.71.173.58]) by mx0a-00128a01.pphosted.com with ESMTP id 36p9gaw2a4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 15 Feb 2021 09:30:26 -0500 Received: from ASHBMBX8.ad.analog.com (ASHBMBX8.ad.analog.com [10.64.17.5]) by nwd2mta4.analog.com (8.14.7/8.14.7) with ESMTP id 11FEUPR8011827 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 15 Feb 2021 09:30:25 -0500 Received: from ASHBCASHYB4.ad.analog.com (10.64.17.132) by ASHBMBX8.ad.analog.com (10.64.17.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.721.2; Mon, 15 Feb 2021 09:30:24 -0500 Received: from ASHBMBX9.ad.analog.com (10.64.17.10) by ASHBCASHYB4.ad.analog.com (10.64.17.132) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.721.2; Mon, 15 Feb 2021 09:30:23 -0500 Received: from zeus.spd.analog.com (10.66.68.11) by ASHBMBX9.ad.analog.com (10.64.17.10) with Microsoft SMTP Server id 15.1.1779.2 via Frontend Transport; Mon, 15 Feb 2021 09:30:23 -0500 Received: from localhost.localdomain ([10.48.65.12]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 11FEUGbk027532; Mon, 15 Feb 2021 09:30:21 -0500 From: Alexandru Ardelean To: , CC: , , , , , Alexandru Ardelean Subject: [PATCH v3 3/5] iio: buffer-dma: split iio_dma_buffer_fileio_free() function Date: Mon, 15 Feb 2021 16:32:32 +0200 Message-ID: <20210215143234.3248-4-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210215143234.3248-1-alexandru.ardelean@analog.com> References: <20210215143234.3248-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-15_08:2021-02-12,2021-02-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 clxscore=1015 mlxscore=0 priorityscore=1501 impostorscore=0 adultscore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102150117 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org A part of the logic in the iio_dma_buffer_exit() is required for the change to add mmap support to IIO buffers. This change splits the logic into a separate function, which will be re-used later. Signed-off-by: Alexandru Ardelean --- drivers/iio/buffer/industrialio-buffer-dma.c | 45 +++++++++++--------- 1 file changed, 25 insertions(+), 20 deletions(-) diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index d348af8b9705..858af7eea53e 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -356,6 +356,30 @@ 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; + } + INIT_LIST_HEAD(&queue->outgoing); + 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) { @@ -635,28 +659,9 @@ 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; - } - INIT_LIST_HEAD(&queue->outgoing); - 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 Mon Feb 15 14:32:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Ardelean X-Patchwork-Id: 12088315 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CCBCC433E0 for ; Mon, 15 Feb 2021 14:31:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E2EF614A5 for ; Mon, 15 Feb 2021 14:31:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230044AbhBOObX (ORCPT ); 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Mon, 15 Feb 2021 06:30:26 -0800 Received: from zeus.spd.analog.com (10.66.68.11) by scsqmbx10.ad.analog.com (10.77.17.5) with Microsoft SMTP Server id 15.2.721.2 via Frontend Transport; Mon, 15 Feb 2021 06:30:25 -0800 Received: from localhost.localdomain ([10.48.65.12]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 11FEUGbl027532; Mon, 15 Feb 2021 09:30:23 -0500 From: Alexandru Ardelean To: , CC: , , , , , Alexandru Ardelean Subject: [PATCH v3 4/5] iio: buffer-dma: Add mmap support Date: Mon, 15 Feb 2021 16:32:33 +0200 Message-ID: <20210215143234.3248-5-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210215143234.3248-1-alexandru.ardelean@analog.com> References: <20210215143234.3248-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-15_08:2021-02-12,2021-02-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 clxscore=1015 mlxscore=0 priorityscore=1501 impostorscore=0 adultscore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102150117 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Lars-Peter Clausen Add support for the new mmap interface to IIO DMA buffer. This interface allows to directly map the backing memory of a block to userspace. This is especially advantageous for high-speed devices where the extra copy from kernel space to userspace of the data incurs a significant overhead. In addition this interface allows more fine grained control over how many blocks are allocated and their size. Signed-off-by: Lars-Peter Clausen Signed-off-by: Alexandru Ardelean --- drivers/iio/buffer/industrialio-buffer-dma.c | 279 +++++++++++++++++- .../buffer/industrialio-buffer-dmaengine.c | 22 +- include/linux/iio/buffer-dma.h | 22 +- 3 files changed, 306 insertions(+), 17 deletions(-) diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c index 858af7eea53e..e187c1640b17 100644 --- a/drivers/iio/buffer/industrialio-buffer-dma.c +++ b/drivers/iio/buffer/industrialio-buffer-dma.c @@ -90,6 +90,9 @@ * callback is called from within the custom callback. */ +static unsigned int iio_dma_buffer_max_block_size = SZ_16M; +module_param_named(max_block_size, iio_dma_buffer_max_block_size, uint, 0644); + static void iio_buffer_block_release(struct kref *kref) { struct iio_dma_buffer_block *block = container_of(kref, @@ -97,7 +100,7 @@ static void iio_buffer_block_release(struct kref *kref) WARN_ON(block->state != IIO_BLOCK_STATE_DEAD); - dma_free_coherent(block->queue->dev, PAGE_ALIGN(block->size), + dma_free_coherent(block->queue->dev, PAGE_ALIGN(block->block.size), block->vaddr, block->phys_addr); iio_buffer_put(&block->queue->buffer); @@ -178,7 +181,7 @@ static struct iio_dma_buffer_block *iio_dma_buffer_alloc_block( return NULL; } - block->size = size; + block->block.size = size; block->state = IIO_BLOCK_STATE_DEQUEUED; block->queue = queue; INIT_LIST_HEAD(&block->head); @@ -243,7 +246,7 @@ void iio_dma_buffer_block_list_abort(struct iio_dma_buffer_queue *queue, spin_lock_irqsave(&queue->list_lock, flags); list_for_each_entry_safe(block, _block, list, head) { list_del(&block->head); - block->bytes_used = 0; + block->block.bytes_used = 0; _iio_dma_buffer_block_done(block); iio_buffer_block_put_atomic(block); } @@ -296,6 +299,10 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) mutex_lock(&queue->lock); + /* If in mmap mode dont do anything */ + if (queue->num_blocks) + goto out_unlock; + /* Allocations are page aligned */ if (PAGE_ALIGN(queue->fileio.block_size) == PAGE_ALIGN(size)) try_reuse = true; @@ -330,7 +337,7 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) iio_buffer_block_put(block); block = NULL; } else { - block->size = size; + block->block.size = size; } } else { block = NULL; @@ -345,6 +352,8 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) queue->fileio.blocks[i] = block; } + block->block.id = i; + block->state = IIO_BLOCK_STATE_QUEUED; list_add_tail(&block->head, &queue->incoming); } @@ -428,6 +437,7 @@ int iio_dma_buffer_enable(struct iio_buffer *buffer, struct iio_dma_buffer_block *block, *_block; mutex_lock(&queue->lock); + queue->fileio.enabled = !queue->num_blocks; queue->active = true; list_for_each_entry_safe(block, _block, &queue->incoming, head) { list_del(&block->head); @@ -453,6 +463,7 @@ int iio_dma_buffer_disable(struct iio_buffer *buffer, struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); mutex_lock(&queue->lock); + queue->fileio.enabled = false; queue->active = false; if (queue->ops && queue->ops->abort) @@ -514,6 +525,11 @@ int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n, mutex_lock(&queue->lock); + if (!queue->fileio.enabled) { + ret = -EBUSY; + goto out_unlock; + } + if (!queue->fileio.active_block) { block = iio_dma_buffer_dequeue(queue); if (block == NULL) { @@ -527,8 +543,8 @@ int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n, } n = rounddown(n, buffer->bytes_per_datum); - if (n > block->bytes_used - queue->fileio.pos) - n = block->bytes_used - queue->fileio.pos; + if (n > block->block.bytes_used - queue->fileio.pos) + n = block->block.bytes_used - queue->fileio.pos; if (copy_to_user(user_buffer, block->vaddr + queue->fileio.pos, n)) { ret = -EFAULT; @@ -537,7 +553,7 @@ int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n, queue->fileio.pos += n; - if (queue->fileio.pos == block->bytes_used) { + if (queue->fileio.pos == block->block.bytes_used) { queue->fileio.active_block = NULL; iio_dma_buffer_enqueue(queue, block); } @@ -573,11 +589,11 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) mutex_lock(&queue->lock); if (queue->fileio.active_block) - data_available += queue->fileio.active_block->size; + data_available += queue->fileio.active_block->block.size; spin_lock_irq(&queue->list_lock); list_for_each_entry(block, &queue->outgoing, head) - data_available += block->size; + data_available += block->block.size; spin_unlock_irq(&queue->list_lock); mutex_unlock(&queue->lock); @@ -585,6 +601,251 @@ size_t iio_dma_buffer_data_available(struct iio_buffer *buf) } EXPORT_SYMBOL_GPL(iio_dma_buffer_data_available); +int iio_dma_buffer_alloc_blocks(struct iio_buffer *buffer, + struct iio_buffer_block_alloc_req *req) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + struct iio_dma_buffer_block **blocks; + unsigned int num_blocks; + unsigned int i; + int ret = 0; + + mutex_lock(&queue->lock); + + /* + * If the buffer is enabled and in fileio mode new blocks can't be + * allocated. + */ + if (queue->fileio.enabled) { + ret = -EBUSY; + goto err_unlock; + } + + /* Free memory that might be in use for fileio mode */ + iio_dma_buffer_fileio_free(queue); + + /* 64 blocks ought to be enough for anybody ;) */ + if (req->count > 64 - queue->num_blocks) + req->count = 64 - queue->num_blocks; + if (req->size > iio_dma_buffer_max_block_size) + req->size = iio_dma_buffer_max_block_size; + + req->id = queue->num_blocks; + + if (req->count == 0 || req->size == 0) { + ret = 0; + goto err_unlock; + } + + num_blocks = req->count + queue->num_blocks; + + blocks = krealloc(queue->blocks, sizeof(*blocks) * num_blocks, + GFP_KERNEL); + if (!blocks) { + ret = -ENOMEM; + goto err_unlock; + } + + for (i = queue->num_blocks; i < num_blocks; i++) { + blocks[i] = iio_dma_buffer_alloc_block(queue, req->size); + if (!blocks[i]) { + ret = -ENOMEM; + goto err_unwind; + } + blocks[i]->block.id = i; + blocks[i]->block.data.offset = queue->max_offset; + queue->max_offset += PAGE_ALIGN(req->size); + } + + req->count = i - queue->num_blocks; + queue->num_blocks = i; + queue->blocks = blocks; + + mutex_unlock(&queue->lock); + + return 0; + +err_unwind: + for (; i >= 0; i--) + iio_buffer_block_put(blocks[i]); + kfree(blocks); +err_unlock: + mutex_unlock(&queue->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_alloc_blocks); + +int iio_dma_buffer_free_blocks(struct iio_buffer *buffer) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + unsigned int i; + + mutex_lock(&queue->lock); + + spin_lock_irq(&queue->list_lock); + INIT_LIST_HEAD(&queue->incoming); + INIT_LIST_HEAD(&queue->outgoing); + + for (i = 0; i < queue->num_blocks; i++) + queue->blocks[i]->state = IIO_BLOCK_STATE_DEAD; + spin_unlock_irq(&queue->list_lock); + + for (i = 0; i < queue->num_blocks; i++) + iio_buffer_block_put(queue->blocks[i]); + + kfree(queue->blocks); + queue->blocks = NULL; + queue->num_blocks = 0; + queue->max_offset = 0; + + mutex_unlock(&queue->lock); + + return 0; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_free_blocks); + +int iio_dma_buffer_query_block(struct iio_buffer *buffer, + struct iio_buffer_block *block) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + int ret = 0; + + mutex_lock(&queue->lock); + + if (block->id >= queue->num_blocks) { + ret = -EINVAL; + goto out_unlock; + } + + *block = queue->blocks[block->id]->block; + +out_unlock: + mutex_unlock(&queue->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_query_block); + +int iio_dma_buffer_enqueue_block(struct iio_buffer *buffer, + struct iio_buffer_block *block) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + struct iio_dma_buffer_block *dma_block; + int ret = 0; + + mutex_lock(&queue->lock); + + if (block->id >= queue->num_blocks) { + ret = -EINVAL; + goto out_unlock; + } + + dma_block = queue->blocks[block->id]; + dma_block->block.bytes_used = block->bytes_used; + dma_block->block.flags = block->flags; + + switch (dma_block->state) { + case IIO_BLOCK_STATE_DONE: + list_del_init(&dma_block->head); + break; + case IIO_BLOCK_STATE_QUEUED: + /* Nothing to do */ + goto out_unlock; + case IIO_BLOCK_STATE_DEQUEUED: + break; + default: + ret = -EBUSY; + goto out_unlock; + } + + iio_dma_buffer_enqueue(queue, dma_block); + +out_unlock: + mutex_unlock(&queue->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_enqueue_block); + +int iio_dma_buffer_dequeue_block(struct iio_buffer *buffer, + struct iio_buffer_block *block) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + struct iio_dma_buffer_block *dma_block; + int ret = 0; + + mutex_lock(&queue->lock); + + dma_block = iio_dma_buffer_dequeue(queue); + if (!dma_block) { + ret = -EAGAIN; + goto out_unlock; + } + + *block = dma_block->block; + +out_unlock: + mutex_unlock(&queue->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_dequeue_block); + +static void iio_dma_buffer_mmap_open(struct vm_area_struct *area) +{ + struct iio_dma_buffer_block *block = area->vm_private_data; + + iio_buffer_block_get(block); +} + +static void iio_dma_buffer_mmap_close(struct vm_area_struct *area) +{ + struct iio_dma_buffer_block *block = area->vm_private_data; + + iio_buffer_block_put(block); +} + +static const struct vm_operations_struct iio_dma_buffer_vm_ops = { + .open = iio_dma_buffer_mmap_open, + .close = iio_dma_buffer_mmap_close, +}; + +int iio_dma_buffer_mmap(struct iio_buffer *buffer, struct vm_area_struct *vma) +{ + struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer); + struct iio_dma_buffer_block *block = NULL; + size_t vm_offset; + unsigned int i; + + vm_offset = vma->vm_pgoff << PAGE_SHIFT; + + for (i = 0; i < queue->num_blocks; i++) { + if (queue->blocks[i]->block.data.offset == vm_offset) { + block = queue->blocks[i]; + break; + } + } + + if (block == NULL) + return -EINVAL; + + if (PAGE_ALIGN(block->block.size) < vma->vm_end - vma->vm_start) + return -EINVAL; + + vma->vm_pgoff = 0; + + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; + vma->vm_ops = &iio_dma_buffer_vm_ops; + vma->vm_private_data = block; + + vma->vm_ops->open(vma); + + return dma_mmap_coherent(queue->dev, vma, block->vaddr, + block->phys_addr, vma->vm_end - vma->vm_start); +} +EXPORT_SYMBOL_GPL(iio_dma_buffer_mmap); + /** * 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/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c index d76179878ff9..6fad5ec9767b 100644 --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c @@ -54,7 +54,7 @@ static void iio_dmaengine_buffer_block_done(void *data, spin_lock_irqsave(&block->queue->list_lock, flags); list_del(&block->head); spin_unlock_irqrestore(&block->queue->list_lock, flags); - block->bytes_used -= result->residue; + block->block.bytes_used -= result->residue; iio_dma_buffer_block_done(block); } @@ -66,12 +66,17 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue, struct dma_async_tx_descriptor *desc; dma_cookie_t cookie; - block->bytes_used = min(block->size, dmaengine_buffer->max_size); - block->bytes_used = rounddown(block->bytes_used, - dmaengine_buffer->align); + block->block.bytes_used = min(block->block.size, + dmaengine_buffer->max_size); + block->block.bytes_used = rounddown(block->block.bytes_used, + dmaengine_buffer->align); + if (block->block.bytes_used == 0) { + iio_dma_buffer_block_done(block); + return 0; + } desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, - block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM, + block->phys_addr, block->block.bytes_used, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT); if (!desc) return -ENOMEM; @@ -120,6 +125,13 @@ static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = { .data_available = iio_dma_buffer_data_available, .release = iio_dmaengine_buffer_release, + .alloc_blocks = iio_dma_buffer_alloc_blocks, + .free_blocks = iio_dma_buffer_free_blocks, + .query_block = iio_dma_buffer_query_block, + .enqueue_block = iio_dma_buffer_enqueue_block, + .dequeue_block = iio_dma_buffer_dequeue_block, + .mmap = iio_dma_buffer_mmap, + .modes = INDIO_BUFFER_HARDWARE, .flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK, }; diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h index 6564bdcdac66..f6f2ce3e2ed1 100644 --- a/include/linux/iio/buffer-dma.h +++ b/include/linux/iio/buffer-dma.h @@ -36,7 +36,7 @@ enum iio_block_state { /** * struct iio_dma_buffer_block - IIO buffer block * @head: List head - * @size: Total size of the block in bytes + * @block: Underlying block object for this DMA buffer block * @bytes_used: Number of bytes that contain valid data * @vaddr: Virutal address of the blocks memory * @phys_addr: Physical address of the blocks memory @@ -47,7 +47,7 @@ enum iio_block_state { struct iio_dma_buffer_block { /* May only be accessed by the owner of the block */ struct list_head head; - size_t bytes_used; + struct iio_buffer_block block; /* * Set during allocation, constant thereafter. May be accessed read-only @@ -55,7 +55,6 @@ struct iio_dma_buffer_block { */ void *vaddr; dma_addr_t phys_addr; - size_t size; struct iio_dma_buffer_queue *queue; /* Must not be accessed outside the core. */ @@ -73,12 +72,14 @@ 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 + * @enabled: Whether the buffer is operating in fileio mode */ 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; + bool enabled; }; /** @@ -109,6 +110,10 @@ struct iio_dma_buffer_queue { bool active; + unsigned int num_blocks; + struct iio_dma_buffer_block **blocks; + unsigned int max_offset; + struct iio_dma_buffer_queue_fileio fileio; }; @@ -143,4 +148,15 @@ 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); +int iio_dma_buffer_alloc_blocks(struct iio_buffer *buffer, + struct iio_buffer_block_alloc_req *req); +int iio_dma_buffer_free_blocks(struct iio_buffer *buffer); +int iio_dma_buffer_query_block(struct iio_buffer *buffer, + struct iio_buffer_block *block); +int iio_dma_buffer_enqueue_block(struct iio_buffer *buffer, + struct iio_buffer_block *block); +int iio_dma_buffer_dequeue_block(struct iio_buffer *buffer, + struct iio_buffer_block *block); +int iio_dma_buffer_mmap(struct iio_buffer *buffer, struct vm_area_struct *vma); + #endif From patchwork Mon Feb 15 14:32:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Ardelean X-Patchwork-Id: 12088313 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28352C433DB for ; Mon, 15 Feb 2021 14:31:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E925E64DEE for ; Mon, 15 Feb 2021 14:31:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229779AbhBOObW (ORCPT ); Mon, 15 Feb 2021 09:31:22 -0500 Received: from mx0a-00128a01.pphosted.com ([148.163.135.77]:44990 "EHLO mx0a-00128a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229933AbhBOObU (ORCPT ); Mon, 15 Feb 2021 09:31:20 -0500 Received: from pps.filterd (m0167089.ppops.net [127.0.0.1]) by mx0a-00128a01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 11FEJl1t031251; Mon, 15 Feb 2021 09:30:28 -0500 Received: from nwd2mta4.analog.com ([137.71.173.58]) by mx0a-00128a01.pphosted.com with ESMTP id 36pcjamst1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 15 Feb 2021 09:30:28 -0500 Received: from ASHBMBX9.ad.analog.com (ASHBMBX9.ad.analog.com [10.64.17.10]) by nwd2mta4.analog.com (8.14.7/8.14.7) with ESMTP id 11FEURKB011830 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=FAIL); Mon, 15 Feb 2021 09:30:27 -0500 Received: from ASHBCASHYB5.ad.analog.com (10.64.17.133) by ASHBMBX9.ad.analog.com (10.64.17.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1779.2; Mon, 15 Feb 2021 09:30:26 -0500 Received: from ASHBMBX8.ad.analog.com (10.64.17.5) by ASHBCASHYB5.ad.analog.com (10.64.17.133) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.721.2; Mon, 15 Feb 2021 09:30:26 -0500 Received: from zeus.spd.analog.com (10.66.68.11) by ashbmbx8.ad.analog.com (10.64.17.5) with Microsoft SMTP Server id 15.2.721.2 via Frontend Transport; Mon, 15 Feb 2021 09:30:26 -0500 Received: from localhost.localdomain ([10.48.65.12]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 11FEUGbm027532; Mon, 15 Feb 2021 09:30:24 -0500 From: Alexandru Ardelean To: , CC: , , , , , Alexandru Ardelean Subject: [PATCH v3 5/5] tools: iio: add example for high-speed buffer support Date: Mon, 15 Feb 2021 16:32:34 +0200 Message-ID: <20210215143234.3248-6-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210215143234.3248-1-alexandru.ardelean@analog.com> References: <20210215143234.3248-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-15_08:2021-02-12,2021-02-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 spamscore=0 bulkscore=0 mlxscore=0 malwarescore=0 suspectscore=0 adultscore=0 clxscore=1015 phishscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102150116 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Following a recent update to the IIO buffer infrastructure, this change adds a basic example on how to access an IIO buffer via the new mmap() interface. The ioctl() for the high-speed mode needs to be enabled right from the start, before setting any parameters via sysfs (length, enable, etc), to make sure that the mmap mode is used and not the fileio mode. Signed-off-by: Alexandru Ardelean --- tools/iio/iio_generic_buffer.c | 184 +++++++++++++++++++++++++++++++-- 1 file changed, 178 insertions(+), 6 deletions(-) diff --git a/tools/iio/iio_generic_buffer.c b/tools/iio/iio_generic_buffer.c index 2491c54a5e4f..99dcc3b339b1 100644 --- a/tools/iio/iio_generic_buffer.c +++ b/tools/iio/iio_generic_buffer.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include "iio_utils.h" @@ -239,6 +240,133 @@ static int enable_disable_all_channels(char *dev_dir_name, int buffer_idx, int e return 0; } +struct mmap_block { + struct iio_buffer_block block; + void *addr; +}; + +static struct mmap_block *enable_high_speed(int buf_fd, unsigned int block_size, + int nblocks) +{ + struct iio_buffer_block_alloc_req req = { 0 }; + struct mmap_block *mmaps = NULL; + int mmaps_cnt = 0; + int i, ret; + + /** + * Validate we can do high-speed by issuing BLOCK_FREE ioctl. + * If using just BLOCK_ALLOC it's distinguish between ENOSYS + * and other error types. + */ + ret = ioctl(buf_fd, IIO_BUFFER_BLOCK_FREE_IOCTL, 0); + if (ret < 0) { + errno = ENOSYS; + return NULL; + } + + /* for now, this */ + req.id = 0; + req.type = 0; + req.size = block_size; + req.count = nblocks; + + ret = ioctl(buf_fd, IIO_BUFFER_BLOCK_ALLOC_IOCTL, &req); + if (ret < 0) + return NULL; + + if (req.count == 0) { + errno = ENOMEM; + return NULL; + } + + if (req.count < nblocks) { + fprintf(stderr, "Requested %d blocks, got %d\n", + nblocks, req.count); + errno = ENOMEM; + return NULL; + } + + mmaps = calloc(req.count, sizeof(*mmaps)); + if (!mmaps) { + errno = ENOMEM; + return NULL; + } + + for (i = 0; i < req.count; i++) { + mmaps[i].block.id = i; + ret = ioctl(buf_fd, IIO_BUFFER_BLOCK_QUERY_IOCTL, &mmaps[i].block); + if (ret < 0) + goto error; + + ret = ioctl(buf_fd, IIO_BUFFER_BLOCK_ENQUEUE_IOCTL, &mmaps[i].block); + if (ret < 0) + goto error; + + mmaps[i].addr = mmap(0, mmaps[i].block.size, + PROT_READ | PROT_WRITE, MAP_SHARED, + buf_fd, mmaps[i].block.data.offset); + + if (mmaps[i].addr == MAP_FAILED) + goto error; + + mmaps_cnt++; + } + + return mmaps; + +error: + for (i = 0; i < mmaps_cnt; i++) + munmap(mmaps[i].addr, mmaps[i].block.size); + free(mmaps); + ioctl(buf_fd, IIO_BUFFER_BLOCK_FREE_IOCTL, 0); + return NULL; +} + +static int read_high_speed(int buf_fd, char *data, unsigned int block_size, + struct mmap_block *mmaps, unsigned int mmaps_cnt) +{ + struct iio_buffer_block block; + int ret; + + /** + * This is where some buffer-pool management can do wonders, + * but for the sake of this sample-code, we're just going to + * copy the data and re-enqueue it back + */ + memset(&block, 0, sizeof(block)); + ret = ioctl(buf_fd, IIO_BUFFER_BLOCK_DEQUEUE_IOCTL, &block); + if (ret < 0) + return ret; + + /* check for weird conditions */ + if (block.bytes_used > block_size) { + fprintf(stderr, + "Got a bigger block (%u) than expected (%u)\n", + block.bytes_used, block_size); + return -EFBIG; + } + + if (block.bytes_used < block_size) { + /** + * This can be normal, with some real-world data + * terminating abruptly. But log it. + */ + fprintf(stderr, + "Got a smaller block (%u) than expected (%u)\n", + block.bytes_used, block_size); + } + + /* memcpy() the data, we lose some more performance here :p */ + memcpy(data, mmaps[block.id].addr, block.bytes_used); + + /* and re-queue this back */ + ret = ioctl(buf_fd, IIO_BUFFER_BLOCK_ENQUEUE_IOCTL, &mmaps[block.id].block); + if (ret < 0) + return ret; + + return block.bytes_used; +} + static void print_usage(void) { fprintf(stderr, "Usage: generic_buffer [options]...\n" @@ -249,6 +377,7 @@ static void print_usage(void) " -c Do n conversions, or loop forever if n < 0\n" " -e Disable wait for event (new data)\n" " -g Use trigger-less mode\n" + " -h Use high-speed buffer access\n" " -l Set buffer length to n samples\n" " --device-name -n \n" " --device-num -N \n" @@ -356,9 +485,15 @@ int main(int argc, char **argv) struct iio_channel_info *channels = NULL; + static bool use_high_speed = false; + unsigned int block_size; + int nblocks = 16; /* default */ + int mmaps_cnt = 0; + struct mmap_block *mmaps = NULL; + register_cleanup(); - while ((c = getopt_long(argc, argv, "aAb:c:egl:n:N:t:T:w:?", longopts, + while ((c = getopt_long(argc, argv, "aAb:c:eghl:n:N:t:T:w:?", longopts, NULL)) != -1) { switch (c) { case 'a': @@ -396,6 +531,9 @@ int main(int argc, char **argv) case 'g': notrigger = 1; break; + case 'h': + use_high_speed = true; + break; case 'l': errno = 0; buf_len = strtoul(optarg, &dummy, 10); @@ -659,6 +797,29 @@ int main(int argc, char **argv) goto error; } + scan_size = size_from_channelarray(channels, num_channels); + block_size = scan_size * buf_len; + /** + * Need to enable high-speed before configuring length/enable. + * Otherwise, the DMA buffer will work in fileio mode, + * and mmap won't work. + */ + if (use_high_speed) { + /** + * The block_size for one block is the same as 'data', but it + * doesn't need to be the same size. It is easier for the sake + * of this example. + */ + mmaps = enable_high_speed(buf_fd, block_size, nblocks); + if (!mmaps) { + fprintf(stderr, "Could not enable high-speed mode\n"); + ret = -errno; + goto error; + } + mmaps_cnt = nblocks; + printf("Using high-speed mode\n"); + } + /* Setup ring buffer parameters */ ret = write_sysfs_int("length", buf_dir_name, buf_len); if (ret < 0) @@ -673,8 +834,7 @@ int main(int argc, char **argv) goto error; } - scan_size = size_from_channelarray(channels, num_channels); - data = malloc(scan_size * buf_len); + data = malloc(block_size); if (!data) { ret = -ENOMEM; goto error; @@ -721,7 +881,13 @@ int main(int argc, char **argv) toread = 64; } - read_size = read(buf_fd, data, toread * scan_size); + if (use_high_speed) { + read_size = read_high_speed(buf_fd, data, block_size, + mmaps, mmaps_cnt); + } else { + read_size = read(buf_fd, data, toread * scan_size); + } + if (read_size < 0) { if (errno == EAGAIN) { fprintf(stderr, "nothing available\n"); @@ -740,8 +906,14 @@ int main(int argc, char **argv) if (fd >= 0 && close(fd) == -1) perror("Failed to close character device"); - if (buf_fd >= 0 && close(buf_fd) == -1) - perror("Failed to close buffer"); + for (i = 0; i < mmaps_cnt; i++) + munmap(mmaps[i].addr, mmaps[i].block.size); + free(mmaps); + if (buf_fd >= 0) { + ioctl(buf_fd, IIO_BUFFER_BLOCK_FREE_IOCTL, 0); + if (close(buf_fd) == -1) + perror("Failed to close buffer"); + } free(buffer_access); free(data); free(buf_dir_name);