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* [PATCH 0/3] iio: core,buffer-dma: add mmap support
@ 2021-02-11 12:33 Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 1/3] iio: core: Add mmap interface infrastructure Alexandru Ardelean
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Alexandru Ardelean @ 2021-02-11 12:33 UTC (permalink / raw)
  To: linux-kernel, linux-iio
  Cc: lars, Michael.Hennerich, jic23, nuno.sa, dragos.bogdan,
	Alexandru Ardelean

This is basically Lars' work adapted from branch:
  https://github.com/larsclausen/linux/commits/iio-high-speed-5.10
[hopefully i got the stuff correctly from that branch]

What is different, is that this one is adapted on top of the multibuffer
support (currently at v5) discussed here:
  https://lore.kernel.org/linux-iio/20210211122452.78106-1-alexandru.ardelean@analog.com/T/#t

Also, adapted an example for high-speed/mmap support in
'tools/iio/iio_generic_buffer.c'

The example is adapted from libiio:
  https://github.com/analogdevicesinc/libiio/blob/master/local.c#L51
but will all the ioctl()s organized after the one that are reserved
(hopefully) for IIO

Tested that mmap() works.
Moved (artifically) valid buffer0 as buffer2 and the operation still
works.

Alexandru Ardelean (1):
  tools: iio: add example for high-speed buffer support

Lars-Peter Clausen (2):
  iio: core: Add mmap interface infrastructure
  iio: buffer-dma: Add mmap support

 drivers/iio/buffer/industrialio-buffer-dma.c  | 314 ++++++++++++++++--
 .../buffer/industrialio-buffer-dmaengine.c    |  22 +-
 drivers/iio/industrialio-buffer.c             | 158 +++++++++
 include/linux/iio/buffer-dma.h                |  25 +-
 include/linux/iio/buffer_impl.h               |  11 +
 include/uapi/linux/iio/buffer.h               |  27 ++
 tools/iio/iio_generic_buffer.c                | 184 +++++++++-
 7 files changed, 694 insertions(+), 47 deletions(-)

-- 
2.17.1


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH 1/3] iio: core: Add mmap interface infrastructure
  2021-02-11 12:33 [PATCH 0/3] iio: core,buffer-dma: add mmap support Alexandru Ardelean
@ 2021-02-11 12:33 ` Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 2/3] iio: buffer-dma: Add mmap support Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 3/3] tools: iio: add example for high-speed buffer support Alexandru Ardelean
  2 siblings, 0 replies; 5+ messages in thread
From: Alexandru Ardelean @ 2021-02-11 12:33 UTC (permalink / raw)
  To: linux-kernel, linux-iio
  Cc: lars, Michael.Hennerich, jic23, nuno.sa, dragos.bogdan,
	Alexandru Ardelean

From: Lars-Peter Clausen <lars@metafoo.de>

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 <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/iio/industrialio-buffer.c | 157 ++++++++++++++++++++++++++++++
 include/linux/iio/buffer-dma.h    |   5 -
 include/linux/iio/buffer_impl.h   |  11 +++
 include/uapi/linux/iio/buffer.h   |  27 +++++
 4 files changed, 195 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 3aa6702a5811..50228df0b09f 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -16,6 +16,7 @@
 #include <linux/fs.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
+#include <linux/mm.h>
 #include <linux/poll.h>
 #include <linux/sched/signal.h>
 
@@ -1370,6 +1371,12 @@ 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;
@@ -1378,18 +1385,24 @@ static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep)
 
 	wake_up(&buffer->pollq);
 	clear_bit(IIO_BUSY_BIT_POS, &buffer->flags);
+	iio_buffer_free_blocks(buffer);
 	iio_device_put(indio_dev);
 	kfree(ib);
 
 	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,
 };
 
@@ -1762,6 +1775,150 @@ 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..0ac809171bb1 100644
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -60,6 +60,17 @@ 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..0e0c95f1c38b 100644
--- a/include/uapi/linux/iio/buffer.h
+++ b/include/uapi/linux/iio/buffer.h
@@ -5,6 +5,33 @@
 #ifndef _UAPI_IIO_BUFFER_H_
 #define _UAPI_IIO_BUFFER_H_
 
+struct iio_buffer_block_alloc_req {
+	__u32 type;
+	__u32 size;
+	__u32 count;
+	__u32 id;
+};
+
+#define IIO_BUFFER_BLOCK_FLAG_TIMESTAMP_VALID	(1 << 0)
+#define IIO_BUFFER_BLOCK_FLAG_CYCLIC		(1 << 1)
+
+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_ */
-- 
2.17.1


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH 2/3] iio: buffer-dma: Add mmap support
  2021-02-11 12:33 [PATCH 0/3] iio: core,buffer-dma: add mmap support Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 1/3] iio: core: Add mmap interface infrastructure Alexandru Ardelean
@ 2021-02-11 12:33 ` Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 3/3] tools: iio: add example for high-speed buffer support Alexandru Ardelean
  2 siblings, 0 replies; 5+ messages in thread
From: Alexandru Ardelean @ 2021-02-11 12:33 UTC (permalink / raw)
  To: linux-kernel, linux-iio
  Cc: lars, Michael.Hennerich, jic23, nuno.sa, dragos.bogdan,
	Alexandru Ardelean

From: Lars-Peter Clausen <lars@metafoo.de>

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 <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/iio/buffer/industrialio-buffer-dma.c  | 314 ++++++++++++++++--
 .../buffer/industrialio-buffer-dmaengine.c    |  22 +-
 drivers/iio/industrialio-buffer.c             |   1 +
 include/linux/iio/buffer-dma.h                |  20 +-
 4 files changed, 321 insertions(+), 36 deletions(-)

diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c
index d348af8b9705..befb0a3d2def 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);
 	}
@@ -356,6 +365,30 @@ 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)
 {
@@ -404,6 +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);
@@ -429,6 +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)
@@ -490,6 +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) {
@@ -503,8 +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;
@@ -513,7 +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);
 	}
@@ -549,11 +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);
 
@@ -561,6 +601,241 @@ 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])
+			break;
+		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;
+
+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
@@ -635,28 +910,9 @@ 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);
diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
index 8ecdbae83414..bb022922ec23 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/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 50228df0b09f..a0d1ad86022f 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -19,6 +19,7 @@
 #include <linux/mm.h>
 #include <linux/poll.h>
 #include <linux/sched/signal.h>
+#include <linux/mm.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/iio-opaque.h>
diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h
index 6564bdcdac66..315a8d750986 100644
--- a/include/linux/iio/buffer-dma.h
+++ b/include/linux/iio/buffer-dma.h
@@ -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
-- 
2.17.1


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH 3/3] tools: iio: add example for high-speed buffer support
  2021-02-11 12:33 [PATCH 0/3] iio: core,buffer-dma: add mmap support Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 1/3] iio: core: Add mmap interface infrastructure Alexandru Ardelean
  2021-02-11 12:33 ` [PATCH 2/3] iio: buffer-dma: Add mmap support Alexandru Ardelean
@ 2021-02-11 12:33 ` Alexandru Ardelean
  2021-02-11 13:14   ` Alexandru Ardelean
  2 siblings, 1 reply; 5+ messages in thread
From: Alexandru Ardelean @ 2021-02-11 12:33 UTC (permalink / raw)
  To: linux-kernel, linux-iio
  Cc: lars, Michael.Hennerich, jic23, nuno.sa, dragos.bogdan,
	Alexandru Ardelean

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 <alexandru.ardelean@analog.com>
---
 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 fdd08514d556..af1a944edcdb 100644
--- a/tools/iio/iio_generic_buffer.c
+++ b/tools/iio/iio_generic_buffer.c
@@ -31,6 +31,7 @@
 #include <stdbool.h>
 #include <signal.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <linux/iio/buffer.h>
 #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);
+	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 <n>     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 <n>     Set buffer length to n samples\n"
 		"  --device-name -n <name>\n"
 		"  --device-num -N <num>\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);
@@ -661,6 +799,29 @@ 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)
@@ -675,8 +836,7 @@ 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;
@@ -719,7 +879,13 @@ 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");
@@ -738,8 +904,14 @@ 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);
-- 
2.17.1


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH 3/3] tools: iio: add example for high-speed buffer support
  2021-02-11 12:33 ` [PATCH 3/3] tools: iio: add example for high-speed buffer support Alexandru Ardelean
@ 2021-02-11 13:14   ` Alexandru Ardelean
  0 siblings, 0 replies; 5+ messages in thread
From: Alexandru Ardelean @ 2021-02-11 13:14 UTC (permalink / raw)
  To: Alexandru Ardelean
  Cc: LKML, linux-iio, Lars-Peter Clausen, Hennerich, Michael,
	Jonathan Cameron, Nuno Sá,
	Bogdan, Dragos

On Thu, Feb 11, 2021 at 2:38 PM Alexandru Ardelean
<alexandru.ardelean@analog.com> wrote:
>
> 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 <alexandru.ardelean@analog.com>
> ---
>  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 fdd08514d556..af1a944edcdb 100644
> --- a/tools/iio/iio_generic_buffer.c
> +++ b/tools/iio/iio_generic_buffer.c
> @@ -31,6 +31,7 @@
>  #include <stdbool.h>
>  #include <signal.h>
>  #include <sys/ioctl.h>
> +#include <sys/mman.h>
>  #include <linux/iio/buffer.h>
>  #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);
> +       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;
> +}
> +

forgot to remove this extra line;
will make a note, for the next re-spin;
after some feedback

> +
>  static void print_usage(void)
>  {
>         fprintf(stderr, "Usage: generic_buffer [options]...\n"
> @@ -249,6 +377,7 @@ static void print_usage(void)
>                 "  -c <n>     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 <n>     Set buffer length to n samples\n"
>                 "  --device-name -n <name>\n"
>                 "  --device-num -N <num>\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);
> @@ -661,6 +799,29 @@ 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)
> @@ -675,8 +836,7 @@ 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;
> @@ -719,7 +879,13 @@ 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");
> @@ -738,8 +904,14 @@ 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);
> --
> 2.17.1
>

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2021-02-11 13:18 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-02-11 12:33 [PATCH 0/3] iio: core,buffer-dma: add mmap support Alexandru Ardelean
2021-02-11 12:33 ` [PATCH 1/3] iio: core: Add mmap interface infrastructure Alexandru Ardelean
2021-02-11 12:33 ` [PATCH 2/3] iio: buffer-dma: Add mmap support Alexandru Ardelean
2021-02-11 12:33 ` [PATCH 3/3] tools: iio: add example for high-speed buffer support Alexandru Ardelean
2021-02-11 13:14   ` Alexandru Ardelean

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