drm/nouveau/volt: add support for non-vid-based voltage controllers

This patch is not ideal but it definitely beats a rewrite of the current
interface and is very self-contained.

Signed-off-by: Martin Peres <martin.peres@free.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c

@@ -30,7 +30,12 @@
 int
 nvkm_volt_get(struct nvkm_volt *volt)
 {
-	int ret = volt->func->vid_get(volt), i;
+	int ret, i;
+
+	if (volt->func->volt_get)
+		return volt->func->volt_get(volt);
+
+	ret = volt->func->vid_get(volt);
 	if (ret >= 0) {
 		for (i = 0; i < volt->vid_nr; i++) {
 			if (volt->vid[i].vid == ret)
@@ -46,6 +51,10 @@ nvkm_volt_set(struct nvkm_volt *volt, u32 uv)
 {
 	struct nvkm_subdev *subdev = &volt->subdev;
 	int i, ret = -EINVAL;
+
+	if (volt->func->volt_set)
+		return volt->func->volt_set(volt, uv);
+
 	for (i = 0; i < volt->vid_nr; i++) {
 		if (volt->vid[i].uv == uv) {
 			ret = volt->func->vid_set(volt, volt->vid[i].vid);

drivers/gpu/drm/nouveau/nvkm/subdev/volt/priv.h

@@ -9,6 +9,8 @@ int nvkm_volt_new_(const struct nvkm_volt_func *, struct nvkm_device *,
 		   int index, struct nvkm_volt **);
 
 struct nvkm_volt_func {
+	int (*volt_get)(struct nvkm_volt *);
+	int (*volt_set)(struct nvkm_volt *, u32 uv);
 	int (*vid_get)(struct nvkm_volt *);
 	int (*vid_set)(struct nvkm_volt *, u8 vid);
 	int (*set_id)(struct nvkm_volt *, u8 id, int condition);