i915: add dma-buf vmap support for exporting vmapped buffer

This is used to export a vmapping to the udl driver so that
i915 and udl can share the udl scanout.

Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 58 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 377c21f531e4..c9cfc67c2cf5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -942,6 +942,9 @@ struct drm_i915_gem_object {
 
         /* prime dma-buf support */
         struct sg_table *sg_table;
+        void *dma_buf_vmapping;
+        int vmapping_count;
+
         /**
          * Used for performing relocations during execbuffer insertion.
          */
diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index 4fba63e896d7..aa308e1337db 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -74,6 +74,59 @@ static void i915_gem_dmabuf_release(struct dma_buf *dma_buf)
         }
 }
 
+static void *i915_gem_dmabuf_vmap(struct dma_buf *dma_buf)
+{
+        struct drm_i915_gem_object *obj = dma_buf->priv;
+        struct drm_device *dev = obj->base.dev;
+        int ret;
+
+        ret = i915_mutex_lock_interruptible(dev);
+        if (ret)
+                return ERR_PTR(ret);
+
+        if (obj->dma_buf_vmapping) {
+                obj->vmapping_count++;
+                goto out_unlock;
+        }
+
+        if (!obj->pages) {
+                ret = i915_gem_object_get_pages_gtt(obj, __GFP_NORETRY | __GFP_NOWARN);
+                if (ret) {
+                        mutex_unlock(&dev->struct_mutex);
+                        return ERR_PTR(ret);
+                }
+        }
+
+        obj->dma_buf_vmapping = vmap(obj->pages, obj->base.size / PAGE_SIZE, 0, PAGE_KERNEL);
+        if (!obj->dma_buf_vmapping) {
+                DRM_ERROR("failed to vmap object\n");
+                goto out_unlock;
+        }
+
+        obj->vmapping_count = 1;
+out_unlock:
+        mutex_unlock(&dev->struct_mutex);
+        return obj->dma_buf_vmapping;
+}
+
+static void i915_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
+{
+        struct drm_i915_gem_object *obj = dma_buf->priv;
+        struct drm_device *dev = obj->base.dev;
+        int ret;
+
+        ret = i915_mutex_lock_interruptible(dev);
+        if (ret)
+                return;
+
+        --obj->vmapping_count;
+        if (obj->vmapping_count == 0) {
+                vunmap(obj->dma_buf_vmapping);
+                obj->dma_buf_vmapping = NULL;
+        }
+        mutex_unlock(&dev->struct_mutex);
+}
+
 static void *i915_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf, unsigned long page_num)
 {
         return NULL;
@@ -107,6 +160,8 @@ static const struct dma_buf_ops i915_dmabuf_ops =  {
         .kunmap = i915_gem_dmabuf_kunmap,
         .kunmap_atomic = i915_gem_dmabuf_kunmap_atomic,
         .mmap = i915_gem_dmabuf_mmap,
+        .vmap = i915_gem_dmabuf_vmap,
+        .vunmap = i915_gem_dmabuf_vunmap,
 };
 
 struct dma_buf *i915_gem_prime_export(struct drm_device *dev,