drm/radeon/kms: add info query for max pipes

The maximum number of pipes is needed by the user space compute
driver to calculate the number of wavefronts per thread group.

Signed-off-by: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 1986eba..72d70eb 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -264,6 +264,19 @@
 			return -EINVAL;
 		value = RADEON_IB_VM_MAX_SIZE;
 		break;
+	case RADEON_INFO_MAX_PIPES:
+		if (rdev->family >= CHIP_CAYMAN)
+			value = rdev->config.cayman.max_pipes_per_simd;
+		else if (rdev->family >= CHIP_CEDAR)
+			value = rdev->config.evergreen.max_pipes;
+		else if (rdev->family >= CHIP_RV770)
+			value = rdev->config.rv770.max_pipes;
+		else if (rdev->family >= CHIP_R600)
+			value = rdev->config.r600.max_pipes;
+		else {
+			return -EINVAL;
+		}
+		break;
 	default:
 		DRM_DEBUG_KMS("Invalid request %d\n", info->request);
 		return -EINVAL;