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Subject[PATCH 3/5] drm: Add and export function drm_gem_cma_mmap_noncoherent
Date
This function can be used by drivers that need to mmap dumb buffers
created with non-coherent backing memory.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
drivers/gpu/drm/drm_gem_cma_helper.c | 39 ++++++++++++++++++++++++++++
include/drm/drm_gem_cma_helper.h | 2 ++
2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 3bdd67795e20..4ed63f4896bd 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -387,6 +387,45 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
}
EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);

+/**
+ * drm_gem_cma_mmap_noncoherent - memory-map a CMA GEM object with
+ * non-coherent cache attribute
+ * @filp: file object
+ * @vma: VMA for the area to be mapped
+ *
+ * Just like drm_gem_cma_mmap, but for a GEM object backed by non-coherent
+ * memory.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_cma_mmap_noncoherent(struct file *filp, struct vm_area_struct *vma)
+{
+ struct drm_gem_cma_object *cma_obj;
+ int ret;
+
+ ret = drm_gem_mmap(filp, vma);
+ if (ret)
+ return ret;
+
+ cma_obj = to_drm_gem_cma_obj(vma->vm_private_data);
+
+ /*
+ * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
+ * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
+ * the whole buffer.
+ */
+ vma->vm_flags &= ~VM_PFNMAP;
+ vma->vm_pgoff = 0;
+ vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+ return remap_pfn_range(vma, vma->vm_start,
+ cma_obj->paddr >> PAGE_SHIFT,
+ vma->vm_end - vma->vm_start,
+ vma->vm_page_prot);
+}
+EXPORT_SYMBOL_GPL(drm_gem_cma_mmap_noncoherent);
+
#ifndef CONFIG_MMU
/**
* drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index d0e6a1cd0950..6b01ad5581c3 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -83,6 +83,8 @@ int drm_gem_cma_dumb_create_noncoherent(struct drm_file *file_priv,
/* set vm_flags and we can change the VM attribute to other one at here */
int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma);

+int drm_gem_cma_mmap_noncoherent(struct file *filep, struct vm_area_struct *vma);
+
/* allocate physical memory */
struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
size_t size);
--
2.28.0
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