drm/msm: add madvise ioctl

Doesn't do anything too interesting until we wire up shrinker.  Pretty
much lifted from i915.

Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 435a8f9..00881f3 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -690,6 +690,44 @@
 	return msm_wait_fence(priv->gpu->fctx, args->fence, &timeout, true);
 }
 
+static int msm_ioctl_gem_madvise(struct drm_device *dev, void *data,
+		struct drm_file *file)
+{
+	struct drm_msm_gem_madvise *args = data;
+	struct drm_gem_object *obj;
+	int ret;
+
+	switch (args->madv) {
+	case MSM_MADV_DONTNEED:
+	case MSM_MADV_WILLNEED:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = mutex_lock_interruptible(&dev->struct_mutex);
+	if (ret)
+		return ret;
+
+	obj = drm_gem_object_lookup(file, args->handle);
+	if (!obj) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+
+	ret = msm_gem_madvise(obj, args->madv);
+	if (ret >= 0) {
+		args->retained = ret;
+		ret = 0;
+	}
+
+	drm_gem_object_unreference(obj);
+
+unlock:
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}
+
 static const struct drm_ioctl_desc msm_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(MSM_GET_PARAM,    msm_ioctl_get_param,    DRM_AUTH|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(MSM_GEM_NEW,      msm_ioctl_gem_new,      DRM_AUTH|DRM_RENDER_ALLOW),
@@ -698,6 +736,7 @@
 	DRM_IOCTL_DEF_DRV(MSM_GEM_CPU_FINI, msm_ioctl_gem_cpu_fini, DRM_AUTH|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(MSM_GEM_SUBMIT,   msm_ioctl_gem_submit,   DRM_AUTH|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(MSM_WAIT_FENCE,   msm_ioctl_wait_fence,   DRM_AUTH|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(MSM_GEM_MADVISE,  msm_ioctl_gem_madvise,  DRM_AUTH|DRM_RENDER_ALLOW),
 };
 
 static const struct vm_operations_struct vm_ops = {