ui: Get the fd associated with udmabuf driver

Try to open the udmabuf dev node for the first time or return the
fd if the device was previously opened.

Based-on-patch-by: Gerd Hoffmann <kraxel@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Message-Id: <20210526231429.1045476-2-vivek.kasireddy@intel.com>

[ kraxel: fixup fcntl.h include ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/ui/udmabuf.c b/ui/udmabuf.c
new file mode 100644
index 0000000000..23abe1e7eb
--- /dev/null
+++ b/ui/udmabuf.c
@@ -0,0 +1,40 @@
+/*
+ * udmabuf helper functions.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "ui/console.h"
+
+#ifdef CONFIG_LINUX
+
+#include <fcntl.h>
+#include <sys/ioctl.h>
+
+int udmabuf_fd(void)
+{
+    static bool first = true;
+    static int udmabuf;
+
+    if (!first) {
+        return udmabuf;
+    }
+    first = false;
+
+    udmabuf = open("/dev/udmabuf", O_RDWR);
+    if (udmabuf < 0) {
+        warn_report("open /dev/udmabuf: %s", strerror(errno));
+    }
+    return udmabuf;
+}
+
+#else
+
+int udmabuf_fd(void)
+{
+    return -1;
+}
+
+#endif