[RFC 1/3] drm/vkms: Add functions to map GEM backing storage

[Haneen Mohammed]

This patch add the necessary functions to map GEM backing memory
into the kernel's virtual address space.

Signed-off-by: Haneen Mohammed <hamohammed...@gmail.com>
---
 drivers/gpu/drm/vkms/vkms_drv.c |  1 +
 drivers/gpu/drm/vkms/vkms_drv.h |  5 ++++
 drivers/gpu/drm/vkms/vkms_gem.c | 50 +++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index c56d66d9ec56..8ab53958e4b9 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -55,6 +55,7 @@ static struct drm_driver vkms_driver = {
        .dumb_create            = vkms_dumb_create,
        .dumb_map_offset        = vkms_dumb_map,
        .gem_vm_ops             = &vkms_gem_vm_ops,
+       .gem_free_object_unlocked = vkms_gem_free_object,
 
        .name                   = DRIVER_NAME,
        .desc                   = DRIVER_DESC,
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index f115e7d1ae03..d6cb8824cee2 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -41,6 +41,7 @@ struct vkms_gem_object {
        struct drm_gem_object gem;
        struct mutex pages_lock; /* Page lock used in page fault handler */
        struct page **pages;
+       void *vaddr;
 };
 
 #define drm_crtc_to_vkms_output(target) \
@@ -67,4 +68,8 @@ int vkms_dumb_create(struct drm_file *file, struct drm_device 
*dev,
 int vkms_dumb_map(struct drm_file *file, struct drm_device *dev,
                  u32 handle, u64 *offset);
 
+void vkms_gem_free_object(struct drm_gem_object *obj);
+
+void *vkms_gem_vmap(struct drm_gem_object *obj);
+
 #endif /* _VKMS_DRV_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_gem.c b/drivers/gpu/drm/vkms/vkms_gem.c
index 9f820f56b9e0..249855dded63 100644
--- a/drivers/gpu/drm/vkms/vkms_gem.c
+++ b/drivers/gpu/drm/vkms/vkms_gem.c
@@ -166,3 +166,53 @@ int vkms_dumb_map(struct drm_file *file, struct drm_device 
*dev,
 
        return ret;
 }
+
+void vkms_gem_free_object(struct drm_gem_object *obj)
+{
+       struct vkms_gem_object *vkms_obj = container_of(obj,
+                                                       struct vkms_gem_object,
+                                                       gem);
+       kvfree(vkms_obj->pages);
+       mutex_destroy(&vkms_obj->pages_lock);
+       drm_gem_object_release(obj);
+       kfree(vkms_obj);
+}
+
+struct page **get_pages(struct vkms_gem_object *vkms_obj)
+{
+       struct drm_gem_object *gem_obj = &vkms_obj->gem;
+       struct page **pages = vkms_obj->pages;
+
+       if (!pages) {
+               mutex_lock(&vkms_obj->pages_lock);
+               pages = drm_gem_get_pages(gem_obj);
+               if (IS_ERR(pages)) {
+                       mutex_unlock(&vkms_obj->pages_lock);
+                       return pages;
+               }
+
+               vkms_obj->pages = pages;
+               mutex_unlock(&vkms_obj->pages_lock);
+       }
+
+       return pages;
+}
+
+void *vkms_gem_vmap(struct drm_gem_object *obj)
+{
+       void *vaddr = NULL;
+       struct vkms_gem_object *vkms_obj = container_of(obj,
+                                                       struct vkms_gem_object,
+                                                       gem);
+       unsigned int n_pages = obj->size >> PAGE_SHIFT;
+       struct page **pages = get_pages(vkms_obj);
+
+       if (IS_ERR(pages)) {
+               DRM_INFO("pages allocation failed %ld\n", PTR_ERR(pages));
+               return vaddr;
+       }
+
+       vaddr = vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);
+
+       return vaddr;
+}
-- 
2.17.1

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