Commit fb09feba authored by Paul Cercueil's avatar Paul Cercueil Committed by Jonathan Cameron
Browse files

iio: buffer-dma: Enable buffer write support 



Adding write support to the buffer-dma code is easy - the write()
function basically needs to do the exact same thing as the read()
function: dequeue a block, read or write the data, enqueue the block
when entirely processed.

Therefore, the iio_buffer_dma_read() and the new iio_buffer_dma_write()
now both call a function iio_buffer_dma_io(), which will perform this
task.

Note that we preemptively reset block->bytes_used to the buffer's size
in iio_dma_buffer_request_update(), as in the future the
iio_dma_buffer_enqueue() function won't reset it.

Signed-off-by: default avatarPaul Cercueil <paul@crapouillou.net>
Reviewed-by: default avatarAlexandru Ardelean <ardeleanalex@gmail.com>
Signed-off-by: default avatarNuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240419-iio-backend-axi-dac-v4-3-5ca45b4de294@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 04ae3b1a

drivers/iio/buffer/industrialio-buffer-dma.c

+73 −16
Original line number Diff line number Diff line
@@ -195,6 +195,18 @@ static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) 
		block->state = IIO_BLOCK_STATE_DONE;

}



static void iio_dma_buffer_queue_wake(struct iio_dma_buffer_queue *queue)

{

	__poll_t flags;



	if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN)

		flags = EPOLLIN | EPOLLRDNORM;

	else

		flags = EPOLLOUT | EPOLLWRNORM;



	wake_up_interruptible_poll(&queue->buffer.pollq, flags);

}



/**

 * iio_dma_buffer_block_done() - Indicate that a block has been completed

 * @block: The completed block
@@ -212,7 +224,7 @@ void iio_dma_buffer_block_done(struct iio_dma_buffer_block *block) 
	spin_unlock_irqrestore(&queue->list_lock, flags);



	iio_buffer_block_put_atomic(block);

	wake_up_interruptible_poll(&queue->buffer.pollq, EPOLLIN | EPOLLRDNORM);

	iio_dma_buffer_queue_wake(queue);

}

EXPORT_SYMBOL_GPL(iio_dma_buffer_block_done);
@@ -241,7 +253,7 @@ void iio_dma_buffer_block_list_abort(struct iio_dma_buffer_queue *queue, 
	}

	spin_unlock_irqrestore(&queue->list_lock, flags);



	wake_up_interruptible_poll(&queue->buffer.pollq, EPOLLIN | EPOLLRDNORM);

	iio_dma_buffer_queue_wake(queue);

}

EXPORT_SYMBOL_GPL(iio_dma_buffer_block_list_abort);
@@ -335,8 +347,24 @@ int iio_dma_buffer_request_update(struct iio_buffer *buffer) 
			queue->fileio.blocks[i] = block;

		}



		/*

		 * block->bytes_used may have been modified previously, e.g. by

		 * iio_dma_buffer_block_list_abort(). Reset it here to the

		 * block's so that iio_dma_buffer_io() will work.

		 */

		block->bytes_used = block->size;



		/*

		 * If it's an input buffer, mark the block as queued, and

		 * iio_dma_buffer_enable() will submit it. Otherwise mark it as

		 * done, which means it's ready to be dequeued.

		 */

		if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN) {

			block->state = IIO_BLOCK_STATE_QUEUED;

			list_add_tail(&block->head, &queue->incoming);

		} else {

			block->state = IIO_BLOCK_STATE_DONE;

		}

	}



out_unlock:
@@ -488,20 +516,12 @@ static struct iio_dma_buffer_block *iio_dma_buffer_dequeue( 
	return block;

}



/**

 * iio_dma_buffer_read() - DMA buffer read callback

 * @buffer: Buffer to read form

 * @n: Number of bytes to read

 * @user_buffer: Userspace buffer to copy the data to

 *

 * Should be used as the read callback for iio_buffer_access_ops

 * struct for DMA buffers.

 */

int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n,

	char __user *user_buffer)

static int iio_dma_buffer_io(struct iio_buffer *buffer, size_t n,

			     char __user *user_buffer, bool is_from_user)

{

	struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buffer);

	struct iio_dma_buffer_block *block;

	void *addr;

	int ret;



	if (n < buffer->bytes_per_datum)
@@ -524,8 +544,13 @@ 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;

	addr = block->vaddr + queue->fileio.pos;



	if (copy_to_user(user_buffer, block->vaddr + queue->fileio.pos, n)) {

	if (is_from_user)

		ret = copy_from_user(addr, user_buffer, n);

	else

		ret = copy_to_user(user_buffer, addr, n);

	if (ret) {

		ret = -EFAULT;

		goto out_unlock;

	}
@@ -544,8 +569,40 @@ int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n, 


	return ret;

}



/**

 * iio_dma_buffer_read() - DMA buffer read callback

 * @buffer: Buffer to read form

 * @n: Number of bytes to read

 * @user_buffer: Userspace buffer to copy the data to

 *

 * Should be used as the read callback for iio_buffer_access_ops

 * struct for DMA buffers.

 */

int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n,

			char __user *user_buffer)

{

	return iio_dma_buffer_io(buffer, n, user_buffer, false);

}

EXPORT_SYMBOL_GPL(iio_dma_buffer_read);



/**

 * iio_dma_buffer_write() - DMA buffer write callback

 * @buffer: Buffer to read form

 * @n: Number of bytes to read

 * @user_buffer: Userspace buffer to copy the data from

 *

 * Should be used as the write callback for iio_buffer_access_ops

 * struct for DMA buffers.

 */

int iio_dma_buffer_write(struct iio_buffer *buffer, size_t n,

			 const char __user *user_buffer)

{

	return iio_dma_buffer_io(buffer, n,

				 (__force __user char *)user_buffer, true);

}

EXPORT_SYMBOL_GPL(iio_dma_buffer_write);



/**

 * iio_dma_buffer_usage() - DMA buffer data_available and

 * space_available callback

include/linux/iio/buffer-dma.h

+2 −0
Original line number Diff line number Diff line
@@ -132,6 +132,8 @@ int iio_dma_buffer_disable(struct iio_buffer *buffer, 
	struct iio_dev *indio_dev);

int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n,

	char __user *user_buffer);

int iio_dma_buffer_write(struct iio_buffer *buffer, size_t n,

			 const char __user *user_buffer);

size_t iio_dma_buffer_usage(struct iio_buffer *buffer);

int iio_dma_buffer_set_bytes_per_datum(struct iio_buffer *buffer, size_t bpd);

int iio_dma_buffer_set_length(struct iio_buffer *buffer, unsigned int length);