libdrm: add drmOpenOnce + drmCloseOnce to libdrm

libdrm/xf86drm.c

@@ -3215,3 +3215,64 @@ int drmMMUnlock(int fd, unsigned memType)
     
     return ret;	
 }
+
+#define DRM_MAX_FDS 16
+static struct {
+   char *BusID;
+   int fd;
+   int refcount;
+} connection[DRM_MAX_FDS];
+
+static int nr_fds = 0;
+
+int drmOpenOnce(void *unused, 
+		const char *BusID,
+		int *newlyopened)
+{
+   int i;
+   int fd;
+   
+   for (i = 0; i < nr_fds; i++)
+      if (strcmp(BusID, connection[i].BusID) == 0) {
+	 connection[i].refcount++;
+	 *newlyopened = 0;
+	 return connection[i].fd;
+      }
+
+   fd = drmOpen(unused, BusID);
+   if (fd <= 0 || nr_fds == DRM_MAX_FDS)
+      return fd;
+   
+   connection[nr_fds].BusID = strdup(BusID);
+   connection[nr_fds].fd = fd;
+   connection[nr_fds].refcount = 1;
+   *newlyopened = 1;
+
+   if (0)
+      fprintf(stderr, "saved connection %d for %s %d\n", 
+              nr_fds, connection[nr_fds].BusID, 
+              strcmp(BusID, connection[nr_fds].BusID));
+
+   nr_fds++;
+
+   return fd;   
+}
+
+void drmCloseOnce(int fd)
+{
+   int i;
+
+   for (i = 0; i < nr_fds; i++) {
+      if (fd == connection[i].fd) {
+	 if (--connection[i].refcount == 0) {
+	    drmClose(connection[i].fd);
+	    free(connection[i].BusID);
+	    
+	    if (i < --nr_fds) 
+	       connection[i] = connection[nr_fds];
+
+	    return;
+	 }
+      }
+   }
+}

libdrm/xf86drm.h

@@ -655,6 +655,9 @@ extern int  drmSLLookupNeighbors(void *l, unsigned long key,
 				 unsigned long *prev_key, void **prev_value,
 				 unsigned long *next_key, void **next_value);
 
+extern int drmOpenOnce(void *unused, const char *BusID, int *newlyopened);
+extern void drmCloseOnce(int fd);
+
 #include "xf86mm.h"
 
 #endif