summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/drm_gem_cma_helper.c
diff options
context:
space:
mode:
authorBenjamin Gaignard <benjamin.gaignard@linaro.org>2017-01-04 12:12:57 +0300
committerDaniel Vetter <daniel.vetter@ffwll.ch>2017-01-06 13:04:54 +0300
commit62a0d98a188cc4ebd8ea54b37d274ec20465e464 (patch)
treebb649f5cc408727179380fce600adeba99b2ebbd /drivers/gpu/drm/drm_gem_cma_helper.c
parent99c48e1e38f0aeaa107ad67c8d91f6c9d9d567a9 (diff)
downloadlinux-62a0d98a188cc4ebd8ea54b37d274ec20465e464.tar.xz
drm: allow to use mmuless SoC
Some SoC without MMU have display driver where a drm/kms driver could be implemented. Before doing such kind of thing drm/kms must allow to use mmuless devices. This patch propose to remove MMU configuration flag and add a cma helper function to help implementing mmuless display driver version 4: - add documentation about drm_gem_cma_get_unmapped_area() - stub it MMU case Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> [danvet: Use recommended struct member references in kernel-doc.] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/1483521177-21794-4-git-send-email-benjamin.gaignard@linaro.org
Diffstat (limited to 'drivers/gpu/drm/drm_gem_cma_helper.c')
-rw-r--r--drivers/gpu/drm/drm_gem_cma_helper.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index e0806a2ad11c..5cf38a474845 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -358,6 +358,77 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
}
EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
+#ifndef CONFIG_MMU
+/**
+ * drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases
+ * @filp: file object
+ * @addr: memory address
+ * @len: buffer size
+ * @pgoff: page offset
+ * @flags: memory flags
+ *
+ * This function is used in noMMU platforms to propose address mapping
+ * for a given buffer.
+ * It's intended to be used as a direct handler for the struct
+ * &file_operations.get_unmapped_area operation.
+ *
+ * Returns:
+ * mapping address on success or a negative error code on failure.
+ */
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags)
+{
+ struct drm_gem_cma_object *cma_obj;
+ struct drm_gem_object *obj = NULL;
+ struct drm_file *priv = filp->private_data;
+ struct drm_device *dev = priv->minor->dev;
+ struct drm_vma_offset_node *node;
+
+ if (drm_device_is_unplugged(dev))
+ return -ENODEV;
+
+ drm_vma_offset_lock_lookup(dev->vma_offset_manager);
+ node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
+ pgoff,
+ len >> PAGE_SHIFT);
+ if (likely(node)) {
+ obj = container_of(node, struct drm_gem_object, vma_node);
+ /*
+ * When the object is being freed, after it hits 0-refcnt it
+ * proceeds to tear down the object. In the process it will
+ * attempt to remove the VMA offset and so acquire this
+ * mgr->vm_lock. Therefore if we find an object with a 0-refcnt
+ * that matches our range, we know it is in the process of being
+ * destroyed and will be freed as soon as we release the lock -
+ * so we have to check for the 0-refcnted object and treat it as
+ * invalid.
+ */
+ if (!kref_get_unless_zero(&obj->refcount))
+ obj = NULL;
+ }
+
+ drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
+
+ if (!obj)
+ return -EINVAL;
+
+ if (!drm_vma_node_is_allowed(node, priv)) {
+ drm_gem_object_unreference_unlocked(obj);
+ return -EACCES;
+ }
+
+ cma_obj = to_drm_gem_cma_obj(obj);
+
+ drm_gem_object_unreference_unlocked(obj);
+
+ return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
+}
+EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
+#endif
+
#ifdef CONFIG_DEBUG_FS
/**
* drm_gem_cma_describe - describe a CMA GEM object for debugfs