diff options
Diffstat (limited to 'drivers/staging/comedi/comedi_buf.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_buf.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c index 1e1df89b5018..8e9b30b26810 100644 --- a/drivers/staging/comedi/comedi_buf.c +++ b/drivers/staging/comedi/comedi_buf.c @@ -161,6 +161,30 @@ int comedi_buf_map_put(struct comedi_buf_map *bm) return 1; } +/* helper for "access" vm operation */ +int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset, + void *buf, int len, int write) +{ + unsigned int pgoff = offset & ~PAGE_MASK; + unsigned long pg = offset >> PAGE_SHIFT; + int done = 0; + + while (done < len && pg < bm->n_pages) { + int l = min_t(int, len - done, PAGE_SIZE - pgoff); + void *b = bm->page_list[pg].virt_addr + pgoff; + + if (write) + memcpy(b, buf, l); + else + memcpy(buf, b, l); + buf += l; + done += l; + pg++; + pgoff = 0; + } + return done; +} + /* returns s->async->buf_map and increments its kref refcount */ struct comedi_buf_map * comedi_buf_map_from_subdev_get(struct comedi_subdevice *s) |