nouveau: introduce object to represent the kernel client

Because NVIF intentionally lacks some of the paths necessary to be
compatible with various mistakes we've made over the years, libdrm
needs to know whether a client has been updated and that it's safe
to make use of the new kernel interfaces.

Clients still using nouveau_device_open()/wrap() will be forced to
make use of ABI16 instead of NVIF.

v2.
- remove lib_version, nothing used it
- leave client-provided pointer unmodified on failure

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Tested-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

nouveau/nouveau-symbol-check

@@ -30,6 +30,8 @@ nouveau_device_del
 nouveau_device_open
 nouveau_device_open_existing
 nouveau_device_wrap
+nouveau_drm_del
+nouveau_drm_new
 nouveau_getparam
 nouveau_object_del
 nouveau_object_find

nouveau/nouveau.c

@@ -195,6 +195,41 @@ nouveau_object_find(struct nouveau_object *obj, uint32_t pclass)
 	return obj;
 }
 
+void
+nouveau_drm_del(struct nouveau_drm **pdrm)
+{
+	free(*pdrm);
+	*pdrm = NULL;
+}
+
+int
+nouveau_drm_new(int fd, struct nouveau_drm **pdrm)
+{
+	struct nouveau_drm *drm;
+	drmVersionPtr ver;
+
+#ifdef DEBUG
+	debug_init(getenv("NOUVEAU_LIBDRM_DEBUG"));
+#endif
+
+	if (!(drm = calloc(1, sizeof(*drm))))
+		return -ENOMEM;
+	drm->fd = fd;
+
+	if (!(ver = drmGetVersion(fd))) {
+		nouveau_drm_del(&drm);
+		return -EINVAL;
+	}
+	*pdrm = drm;
+
+	drm->version = (ver->version_major << 24) |
+		       (ver->version_minor << 8) |
+		        ver->version_patchlevel;
+	drm->nvif = false;
+	drmFreeVersion(ver);
+	return 0;
+}
+
 /* this is the old libdrm's version of nouveau_device_wrap(), the symbol
  * is kept here to prevent AIGLX from crashing if the DDX is linked against
  * the new libdrm, but the DRI driver against the old

nouveau/nouveau.h

@@ -22,6 +22,24 @@ struct nouveau_object {
 	void *data;
 };
 
+struct nouveau_drm {
+	struct nouveau_object client;
+	int fd;
+	uint32_t version;
+	bool nvif;
+};
+
+static inline struct nouveau_drm *
+nouveau_drm(struct nouveau_object *obj)
+{
+	while (obj && obj->parent)
+		obj = obj->parent;
+	return (struct nouveau_drm *)obj;
+}
+
+int nouveau_drm_new(int fd, struct nouveau_drm **);
+void nouveau_drm_del(struct nouveau_drm **);
+
 struct nouveau_fifo {
 	struct nouveau_object *object;
 	uint32_t channel;