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authorLars-Peter Clausen <lars@metafoo.de>2013-11-25 18:56:00 +0400
committerJonathan Cameron <jic23@kernel.org>2013-12-04 00:22:28 +0400
commit647cc7b9be861e01723a3183f5d06729a1613a97 (patch)
treeee1dfdc4fc2f51b8af65bf5e5de09c9be1969bb7
parent112b0b79b2e7a552e8afe19fdddbacef734649f8 (diff)
downloadlinux-647cc7b9be861e01723a3183f5d06729a1613a97.tar.xz
iio: Add data_available callback for buffers
This patch adds a new data_available() callback to the iio_buffer_access_funcs struct. The callback is used to indicate whether data is available in the buffer for reading. It is meant to replace the stufftoread flag from the iio_buffer struct. The reasoning for this is that the buffer implementation usually can determine whether data is available rather easily based on its state, on the other hand it can be rather tricky to update the stufftoread flag in a race free way. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
-rw-r--r--drivers/iio/industrialio-buffer.c10
-rw-r--r--include/linux/iio/buffer.h3
2 files changed, 12 insertions, 1 deletions
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 7f9152c3c4d3..4dcc3a0f9930 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -37,6 +37,14 @@ static bool iio_buffer_is_active(struct iio_buffer *buf)
return !list_empty(&buf->buffer_list);
}
+static bool iio_buffer_data_available(struct iio_buffer *buf)
+{
+ if (buf->access->data_available)
+ return buf->access->data_available(buf);
+
+ return buf->stufftoread;
+}
+
/**
* iio_buffer_read_first_n_outer() - chrdev read for buffer access
*
@@ -70,7 +78,7 @@ unsigned int iio_buffer_poll(struct file *filp,
return -ENODEV;
poll_wait(filp, &rb->pollq, wait);
- if (rb->stufftoread)
+ if (iio_buffer_data_available(rb))
return POLLIN | POLLRDNORM;
/* need a way of knowing if there may be enough data... */
return 0;
diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h
index 15607b45221a..519392763393 100644
--- a/include/linux/iio/buffer.h
+++ b/include/linux/iio/buffer.h
@@ -21,6 +21,8 @@ struct iio_buffer;
* struct iio_buffer_access_funcs - access functions for buffers.
* @store_to: actually store stuff to the buffer
* @read_first_n: try to get a specified number of bytes (must exist)
+ * @data_available: indicates whether data for reading from the buffer is
+ * available.
* @request_update: if a parameter change has been marked, update underlying
* storage.
* @get_bytes_per_datum:get current bytes per datum
@@ -43,6 +45,7 @@ struct iio_buffer_access_funcs {
int (*read_first_n)(struct iio_buffer *buffer,
size_t n,
char __user *buf);
+ bool (*data_available)(struct iio_buffer *buffer);
int (*request_update)(struct iio_buffer *buffer);