drm/nouveau: Add getparam to get available PGRAPH units.

On nv50, this will be needed by applications using CUDA to know
how much stack/local memory to allocate.
Signed-off-by: NMarcin Kościelnicki <koriakin@0x04.net>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_reg.h

@@ -99,6 +99,7 @@
  * the card will hang early on in the X init process.
  */
 #    define NV_PMC_ENABLE_UNK13                               (1<<13)
+#define NV40_PMC_GRAPH_UNITS				   0x00001540
 #define NV40_PMC_BACKLIGHT				   0x000015f0
 #	define NV40_PMC_BACKLIGHT_MASK			   0x001f0000
 #define NV40_PMC_1700                                      0x00001700

drivers/gpu/drm/nouveau/nouveau_state.c

@@ -825,6 +825,15 @@ int nouveau_ioctl_getparam(struct drm_device *dev, void *data,
 	case NOUVEAU_GETPARAM_VM_VRAM_BASE:
 		getparam->value = dev_priv->vm_vram_base;
 		break;
+	case NOUVEAU_GETPARAM_GRAPH_UNITS:
+		/* NV40 and NV50 versions are quite different, but register
+		 * address is the same. User is supposed to know the card
+		 * family anyway... */
+		if (dev_priv->chipset >= 0x40) {
+			getparam->value = nv_rd32(dev, NV40_PMC_GRAPH_UNITS);
+			break;
+		}
+		/* FALLTHRU */
 	default:
 		NV_ERROR(dev, "unknown parameter %lld\n", getparam->param);
 		return -EINVAL;

include/drm/nouveau_drm.h

@@ -77,6 +77,7 @@ struct drm_nouveau_gpuobj_free {
 #define NOUVEAU_GETPARAM_PCI_PHYSICAL    10
 #define NOUVEAU_GETPARAM_CHIPSET_ID      11
 #define NOUVEAU_GETPARAM_VM_VRAM_BASE    12
+#define NOUVEAU_GETPARAM_GRAPH_UNITS     13
 struct drm_nouveau_getparam {
 	uint64_t param;
 	uint64_t value;