From: Ian Abbott Date: Fri, 9 Oct 2015 11:26:49 +0000 (+0100) Subject: staging: comedi: add new comedi_buf_write_n_available() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=432fbde739583140c7ee937910786a9d740804c9;p=linux-beck.git staging: comedi: add new comedi_buf_write_n_available() Add a new function `comedi_buf_write_n_available()` to return the amount of buffer space available for writing, including space already allocated by `comedi_buf_write_alloc()` plus any unallocated space available. This is currently just for internal use by the comedi core, so is not exported. Signed-off-by: Ian Abbott Reviewed-by: H Hartley Sweeten Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c index 4837559ac6b8..90c28016c6c1 100644 --- a/drivers/staging/comedi/comedi_buf.c +++ b/drivers/staging/comedi/comedi_buf.c @@ -253,6 +253,14 @@ static unsigned int comedi_buf_write_n_unalloc(struct comedi_subdevice *s) return free_end - async->buf_write_alloc_count; } +unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s) +{ + struct comedi_async *async = s->async; + unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; + + return free_end - async->buf_write_count; +} + /** * comedi_buf_write_alloc() - Reserve buffer space for writing * @s: COMEDI subdevice. diff --git a/drivers/staging/comedi/comedi_internal.h b/drivers/staging/comedi/comedi_internal.h index cd9437f72c35..3f2c88ae6470 100644 --- a/drivers/staging/comedi/comedi_internal.h +++ b/drivers/staging/comedi/comedi_internal.h @@ -31,6 +31,7 @@ void comedi_buf_map_get(struct comedi_buf_map *bm); int comedi_buf_map_put(struct comedi_buf_map *bm); struct comedi_buf_map *comedi_buf_map_from_subdev_get( struct comedi_subdevice *s); +unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s); unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s); void comedi_device_cancel_all(struct comedi_device *dev); bool comedi_can_auto_free_spriv(struct comedi_subdevice *s);