drm/exynos: add vm_ops to specific gem mmaper

Changelog v3:
use drm_file's file object instead of gem object's
- gem object's file represents the shmem storage so
  process-unique file object should be used instead.

Changelog v2:
call mutex_lock before drm_vm_open_locked is called.

Changelog v1:
This patch makes it takes a reference to gem object when
specific gem mmap is requested. For this, it sets
dev->driver->gem_vm_ops to vma->vm_ops.

And this patch is based on exynos-drm-next-iommu branch of
	git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 70 insertions, 5 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 2cc6b3ae4e07..52187aec8692 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -349,17 +349,53 @@ int exynos_drm_gem_map_offset_ioctl(struct drm_device *dev, void *data,
                         &args->offset);
 }
 
+static struct drm_file *exynos_drm_find_drm_file(struct drm_device *drm_dev,
+                                                        struct file *filp)
+{
+        struct drm_file *file_priv;
+
+        mutex_lock(&drm_dev->struct_mutex);
+
+        /* find current process's drm_file from filelist. */
+        list_for_each_entry(file_priv, &drm_dev->filelist, lhead) {
+                if (file_priv->filp == filp) {
+                        mutex_unlock(&drm_dev->struct_mutex);
+                        return file_priv;
+                }
+        }
+
+        mutex_unlock(&drm_dev->struct_mutex);
+        WARN_ON(1);
+
+        return ERR_PTR(-EFAULT);
+}
+
 static int exynos_drm_gem_mmap_buffer(struct file *filp,
                                       struct vm_area_struct *vma)
 {
         struct drm_gem_object *obj = filp->private_data;
         struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
+        struct drm_device *drm_dev = obj->dev;
         struct exynos_drm_gem_buf *buffer;
+        struct drm_file *file_priv;
         unsigned long vm_size;
+        int ret;
 
         DRM_DEBUG_KMS("%s\n", __FILE__);
 
         vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
+        vma->vm_private_data = obj;
+        vma->vm_ops = drm_dev->driver->gem_vm_ops;
+
+        /* restore it to driver's fops. */
+        filp->f_op = fops_get(drm_dev->driver->fops);
+
+        file_priv = exynos_drm_find_drm_file(drm_dev, filp);
+        if (IS_ERR(file_priv))
+                return PTR_ERR(file_priv);
+
+        /* restore it to drm_file. */
+        filp->private_data = file_priv;
 
         update_vm_cache_attr(exynos_gem_obj, vma);
 
@@ -375,9 +411,25 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
         if (vm_size > buffer->size)
                 return -EINVAL;
 
-        return dma_mmap_attrs(obj->dev->dev, vma, buffer->kvaddr,
+        ret = dma_mmap_attrs(drm_dev->dev, vma, buffer->kvaddr,
                                 buffer->dma_addr, buffer->size,
                                 &buffer->dma_attrs);
+        if (ret < 0) {
+                DRM_ERROR("failed to mmap.\n");
+                return ret;
+        }
+
+        /*
+         * take a reference to this mapping of the object. And this reference
+         * is unreferenced by the corresponding vm_close call.
+         */
+        drm_gem_object_reference(obj);
+
+        mutex_lock(&drm_dev->struct_mutex);
+        drm_vm_open_locked(drm_dev, vma);
+        mutex_unlock(&drm_dev->struct_mutex);
+
+        return 0;
 }
 
 static const struct file_operations exynos_drm_gem_fops = {
@@ -404,16 +456,29 @@ int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data,
                 return -EINVAL;
         }
 
-        obj->filp->f_op = &exynos_drm_gem_fops;
-        obj->filp->private_data = obj;
+        /*
+         * Set specific mmper's fops. And it will be restored by
+         * exynos_drm_gem_mmap_buffer to dev->driver->fops.
+         * This is used to call specific mapper temporarily.
+         */
+        file_priv->filp->f_op = &exynos_drm_gem_fops;
+
+        /*
+         * Set gem object to private_data so that specific mmaper
+         * can get the gem object. And it will be restored by
+         * exynos_drm_gem_mmap_buffer to drm_file.
+         */
+        file_priv->filp->private_data = obj;
 
-        addr = vm_mmap(obj->filp, 0, args->size,
+        addr = vm_mmap(file_priv->filp, 0, args->size,
                         PROT_READ | PROT_WRITE, MAP_SHARED, 0);
 
         drm_gem_object_unreference_unlocked(obj);
 
-        if (IS_ERR((void *)addr))
+        if (IS_ERR((void *)addr)) {
+                file_priv->filp->private_data = file_priv;
                 return PTR_ERR((void *)addr);
+        }
 
         args->mapped = addr;