From ee551a10006f3728c231bbe9c30635ff53250dbc Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Mon, 25 Nov 2013 14:56:00 +0000 Subject: [PATCH] iio: Add support for blocking IO on buffers Currently the IIO buffer interface only allows non-blocking reads. This patch adds support for blocking IO. In blocking mode the thread will go to sleep if no data is available and will wait for the buffer implementation to signal that new data is available by waking up the buffers waitqueue. Signed-off-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- drivers/iio/industrialio-buffer.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 4dcc3a0f9930..c67d83bdc8f0 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -56,13 +56,34 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, { struct iio_dev *indio_dev = filp->private_data; struct iio_buffer *rb = indio_dev->buffer; + int ret; if (!indio_dev->info) return -ENODEV; if (!rb || !rb->access->read_first_n) return -EINVAL; - return rb->access->read_first_n(rb, n, buf); + + do { + if (!iio_buffer_data_available(rb)) { + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(rb->pollq, + iio_buffer_data_available(rb) || + indio_dev->info == NULL); + if (ret) + return ret; + if (indio_dev->info == NULL) + return -ENODEV; + } + + ret = rb->access->read_first_n(rb, n, buf); + if (ret == 0 && (filp->f_flags & O_NONBLOCK)) + ret = -EAGAIN; + } while (ret == 0); + + return ret; } /** -- 2.20.1