[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.sa at 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