iio: kfifo-buffer: Add output buffer support

Add output buffer support to the kfifo buffer implementation.

The implementation is straight forward and mostly just wraps the kfifo
API to provide the required operations.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Mihail Chindris <mihail.chindris@analog.com>
Link: https://lore.kernel.org/r/20211007080035.2531-3-mihail.chindris@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/buffer/kfifo_buf.c b/drivers/iio/buffer/kfifo_buf.c
index 516eb3465de164c6316e166e83a98d6fb3c40a8a..416d35a61ae2d44c6dd7a1875a80a2548dfb729a 100644 (file)
--- a/drivers/iio/buffer/kfifo_buf.c
+++ b/drivers/iio/buffer/kfifo_buf.c
@@ -138,10 +138,60 @@ static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
        kfree(kf);
 }
 
+static size_t iio_kfifo_buf_space_available(struct iio_buffer *r)
+{
+       struct iio_kfifo *kf = iio_to_kfifo(r);
+       size_t avail;
+
+       mutex_lock(&kf->user_lock);
+       avail = kfifo_avail(&kf->kf);
+       mutex_unlock(&kf->user_lock);
+
+       return avail;
+}
+
+static int iio_kfifo_remove_from(struct iio_buffer *r, void *data)
+{
+       int ret;
+       struct iio_kfifo *kf = iio_to_kfifo(r);
+
+       if (kfifo_size(&kf->kf) < 1)
+               return -EBUSY;
+
+       ret = kfifo_out(&kf->kf, data, 1);
+       if (ret != 1)
+               return -EBUSY;
+
+       wake_up_interruptible_poll(&r->pollq, EPOLLOUT | EPOLLWRNORM);
+
+       return 0;
+}
+
+static int iio_kfifo_write(struct iio_buffer *r, size_t n,
+       const char __user *buf)
+{
+       struct iio_kfifo *kf = iio_to_kfifo(r);
+       int ret, copied;
+
+       mutex_lock(&kf->user_lock);
+       if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
+               ret = -EINVAL;
+       else
+               ret = kfifo_from_user(&kf->kf, buf, n, &copied);
+       mutex_unlock(&kf->user_lock);
+       if (ret)
+               return ret;
+
+       return copied;
+}
+
 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
        .store_to = &iio_store_to_kfifo,
        .read = &iio_read_kfifo,
        .data_available = iio_kfifo_buf_data_available,
+       .remove_from = &iio_kfifo_remove_from,
+       .write = &iio_kfifo_write,
+       .space_available = &iio_kfifo_buf_space_available,
        .request_update = &iio_request_update_kfifo,
        .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
        .set_length = &iio_set_length_kfifo,