xf86drm: add drmGetNodeTypeFromDevId

This is useful to figure out whether the dev_t refers to a primary
node or a render node. Indeed, drmGetDeviceFromDevId returns a
drmDevice, which holds both the primary and render nodes.

Signed-off-by: Simon Ser <contact@emersion.fr>

core-symbols.txt

@@ -70,6 +70,7 @@ drmGetLibVersion
 drmGetLock
 drmGetMagic
 drmGetMap
+drmGetNodeTypeFromDevId
 drmGetNodeTypeFromFd
 drmGetPrimaryDeviceNameFromFd
 drmGetRenderDeviceNameFromFd

xf86drm.c

@@ -4687,6 +4687,23 @@ drm_public int drmGetDeviceFromDevId(dev_t find_rdev, uint32_t flags, drmDeviceP
 #endif
 }
 
+drm_public int drmGetNodeTypeFromDevId(dev_t devid)
+{
+    int maj, min, node_type;
+
+    maj = major(devid);
+    min = minor(devid);
+
+    if (!drmNodeIsDRM(maj, min))
+        return -EINVAL;
+
+    node_type = drmGetMinorType(maj, min);
+    if (node_type == -1)
+        return -ENODEV;
+
+    return node_type;
+}
+
 /**
  * Get information about the opened drm device
  *

xf86drm.h

@@ -919,6 +919,13 @@ extern int drmGetDevices2(uint32_t flags, drmDevicePtr devices[], int max_device
 
 extern int drmGetDeviceFromDevId(dev_t dev_id, uint32_t flags, drmDevicePtr *device);
 
+/**
+ * Get the node type (DRM_NODE_PRIMARY or DRM_NODE_RENDER) from a device ID.
+ *
+ * Returns negative errno on error.
+ */
+extern int drmGetNodeTypeFromDevId(dev_t devid);
+
 extern int drmDevicesEqual(drmDevicePtr a, drmDevicePtr b);
 
 extern int drmSyncobjCreate(int fd, uint32_t flags, uint32_t *handle);