On Wed, Feb 9, 2022 at 9:10 AM Paul Cercueil paul@crapouillou.net wrote:
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.
The .space_available() callback can return the exact same value as the .data_available() callback for input buffers, since in both cases we count the exact same thing (the number of bytes in each available block).
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.
...
v2: - Fix block->state not being reset in iio_dma_buffer_request_update() for output buffers. - Only update block->bytes_used once and add a comment about why we update it. - Add a comment about why we're setting a different state for output buffers in iio_dma_buffer_request_update() - Remove useless cast to bool (!!) in iio_dma_buffer_io()
Usual place for changelog is after the cutter '--- ' line below...
Signed-off-by: Paul Cercueil paul@crapouillou.net Reviewed-by: Alexandru Ardelean ardeleanalex@gmail.com
...somewhere here.
drivers/iio/buffer/industrialio-buffer-dma.c | 88 ++++++++++++++++---- include/linux/iio/buffer-dma.h | 7 ++
...
+static int iio_dma_buffer_io(struct iio_buffer *buffer,
size_t n, char __user *user_buffer, bool is_write)
I believe there is a room for size_t n on the previous line.
...
if (is_write)
I would name it is_from_user.
ret = copy_from_user(addr, user_buffer, n);elseret = copy_to_user(user_buffer, addr, n);
...
+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 char *)user_buffer, true);
Why do you drop address space markers?
+}