iio: kfifo - add poll support.

This buffer implementation was missing poll support.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: srinivas pandruvada <srinivas.pandruvada@intel.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/iio/kfifo_buf.c b/drivers/iio/kfifo_buf.c
index 6ec763f1202a..63da42498a9a 100644
--- a/drivers/iio/kfifo_buf.c
+++ b/drivers/iio/kfifo_buf.c
@@ -6,6 +6,7 @@
 #include <linux/kfifo.h>
 #include <linux/mutex.h>
 #include <linux/iio/kfifo_buf.h>
+#include <linux/sched.h>
 
 struct iio_kfifo {
         struct iio_buffer buffer;
@@ -36,6 +37,7 @@ static int iio_request_update_kfifo(struct iio_buffer *r)
         kfifo_free(&buf->kf);
         ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
                                    buf->buffer.length);
+        r->stufftoread = false;
 error_ret:
         return ret;
 }
@@ -82,6 +84,9 @@ static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
 
 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
 {
+        /* Avoid an invalid state */
+        if (length < 2)
+                length = 2;
         if (r->length != length) {
                 r->length = length;
                 iio_mark_update_needed_kfifo(r);
@@ -98,6 +103,8 @@ static int iio_store_to_kfifo(struct iio_buffer *r,
         ret = kfifo_in(&kf->kf, data, 1);
         if (ret != 1)
                 return -EBUSY;
+        r->stufftoread = true;
+        wake_up_interruptible(&r->pollq);
 
         return 0;
 }
@@ -115,6 +122,12 @@ static int iio_read_first_n_kfifo(struct iio_buffer *r,
         if (ret < 0)
                 return ret;
 
+        if (kfifo_is_empty(&kf->kf))
+                r->stufftoread = false;
+        /* verify it is still empty to avoid race */
+        if (!kfifo_is_empty(&kf->kf))
+                r->stufftoread = true;
+
         return copied;
 }
 
@@ -139,7 +152,7 @@ struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
         iio_buffer_init(&kf->buffer);
         kf->buffer.attrs = &iio_kfifo_attribute_group;
         kf->buffer.access = &kfifo_access_funcs;
-
+        kf->buffer.length = 2;
         return &kf->buffer;
 }
 EXPORT_SYMBOL(iio_kfifo_allocate);