[PATCH v7] drm: Add library for shmem backed GEM objects
Rob Herring
robh at kernel.org
Wed Mar 6 23:01:44 UTC 2019
From: Noralf Trønnes <noralf at tronnes.org>
This adds a library for shmem backed GEM objects.
v7:
- Use write-combine for mmap instead. This is the more common
case. (robher)
v6:
- Fix uninitialized variable issue in an error path (anholt).
- Add a drm_gem_shmem_vm_open() to the fops to get proper refcounting
of the pages (anholt).
v5:
- Drop drm_gem_shmem_prime_mmap() (Daniel Vetter)
- drm_gem_shmem_mmap(): Subtract drm_vma_node_start() to get the real
vma->vm_pgoff
- drm_gem_shmem_fault(): Use vmf->pgoff now that vma->vm_pgoff is correct
v4:
- Drop cache modes (Thomas Hellstrom)
- Add a GEM attached vtable
v3:
- Grammar (Sam Ravnborg)
- s/drm_gem_shmem_put_pages_unlocked/drm_gem_shmem_put_pages_locked/
(Sam Ravnborg)
- Add debug output in error path (Sam Ravnborg)
Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
Signed-off-by: Eric Anholt <eric at anholt.net>
Signed-off-by: Rob Herring <robh at kernel.org>
---
I don't have a user to submit just yet, but we are using this for
panfrost which can be seen here[1]. I expect we'll be ready to merge
panfrost for 5.2.
Rob
[1] https://gitlab.freedesktop.org/panfrost/linux/blob/panfrost-5.0-rc4/drivers/gpu/drm/panfrost/panfrost_gem.c
Documentation/gpu/drm-kms-helpers.rst | 12 +
drivers/gpu/drm/Kconfig | 6 +
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/drm_gem_shmem_helper.c | 560 +++++++++++++++++++++++++
include/drm/drm_gem_shmem_helper.h | 153 +++++++
5 files changed, 732 insertions(+)
create mode 100644 drivers/gpu/drm/drm_gem_shmem_helper.c
create mode 100644 include/drm/drm_gem_shmem_helper.h
diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst
index b422eb8edf16..44e47ddc21d6 100644
--- a/Documentation/gpu/drm-kms-helpers.rst
+++ b/Documentation/gpu/drm-kms-helpers.rst
@@ -347,3 +347,15 @@ Legacy CRTC/Modeset Helper Functions Reference
.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c
:export:
+
+SHMEM GEM Helper Reference
+==========================
+
+.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c
+ :doc: overview
+
+.. kernel-doc:: include/drm/drm_gem_shmem_helper.h
+ :internal:
+
+.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c
+ :export:
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 4385f00e1d05..0dedbc040c77 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -177,6 +177,12 @@ config DRM_KMS_CMA_HELPER
help
Choose this if you need the KMS CMA helper functions
+config DRM_GEM_SHMEM_HELPER
+ bool
+ depends on DRM
+ help
+ Choose this if you need the GEM shmem helper functions
+
config DRM_VM
bool
depends on DRM && MMU
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index ce8d1d384319..203b311f12ae 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -25,6 +25,7 @@ drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o
drm-$(CONFIG_DRM_VM) += drm_vm.o
drm-$(CONFIG_COMPAT) += drm_ioc32.o
drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o
+drm-$(CONFIG_DRM_GEM_SHMEM_HELPER) += drm_gem_shmem_helper.o
drm-$(CONFIG_PCI) += ati_pcigart.o
drm-$(CONFIG_DRM_PANEL) += drm_panel.o
drm-$(CONFIG_OF) += drm_of.o
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
new file mode 100644
index 000000000000..3394768e067c
--- /dev/null
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -0,0 +1,560 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 Noralf Trønnes
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/shmem_fs.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_prime.h>
+#include <drm/drm_print.h>
+
+/**
+ * DOC: overview
+ *
+ * This library provides helpers for GEM objects backed by shmem buffers
+ * allocated using anonymous pageable memory.
+ */
+
+static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
+ .free = drm_gem_shmem_free_object,
+ .print_info = drm_gem_shmem_print_info,
+ .pin = drm_gem_shmem_pin,
+ .unpin = drm_gem_shmem_unpin,
+ .get_sg_table = drm_gem_shmem_get_sg_table,
+ .vmap = drm_gem_shmem_vmap,
+ .vunmap = drm_gem_shmem_vunmap,
+ .vm_ops = &drm_gem_shmem_vm_ops,
+};
+
+/**
+ * drm_gem_shmem_create - Allocate an object with the given size
+ * @dev: DRM device
+ * @size: Size of the object to allocate
+ *
+ * This function creates a shmem GEM object.
+ *
+ * Returns:
+ * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
+ * error code on failure.
+ */
+struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
+{
+ struct drm_gem_shmem_object *shmem;
+ struct drm_gem_object *obj;
+ int ret;
+
+ size = PAGE_ALIGN(size);
+
+ if (dev->driver->gem_create_object)
+ obj = dev->driver->gem_create_object(dev, size);
+ else
+ obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
+ if (!obj)
+ return ERR_PTR(-ENOMEM);
+
+ if (!obj->funcs)
+ obj->funcs = &drm_gem_shmem_funcs;
+
+ ret = drm_gem_object_init(dev, obj, size);
+ if (ret)
+ goto err_free;
+
+ ret = drm_gem_create_mmap_offset(obj);
+ if (ret)
+ goto err_release;
+
+ shmem = to_drm_gem_shmem_obj(obj);
+ mutex_init(&shmem->pages_lock);
+ mutex_init(&shmem->vmap_lock);
+
+ return shmem;
+
+err_release:
+ drm_gem_object_release(obj);
+err_free:
+ kfree(obj);
+
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
+
+/**
+ * drm_gem_shmem_free_object - Free resources associated with a shmem GEM object
+ * @obj: GEM object to free
+ *
+ * This function cleans up the GEM object state and frees the memory used to
+ * store the object itself.
+ */
+void drm_gem_shmem_free_object(struct drm_gem_object *obj)
+{
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ WARN_ON(shmem->vmap_use_count);
+
+ if (obj->import_attach) {
+ shmem->pages_use_count--;
+ drm_prime_gem_destroy(obj, shmem->sgt);
+ kvfree(shmem->pages);
+ }
+
+ WARN_ON(shmem->pages_use_count);
+
+ drm_gem_object_release(obj);
+ mutex_destroy(&shmem->pages_lock);
+ mutex_destroy(&shmem->vmap_lock);
+ kfree(shmem);
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_free_object);
+
+static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
+{
+ struct drm_gem_object *obj = &shmem->base;
+ struct page **pages;
+
+ if (shmem->pages_use_count++ > 0)
+ return 0;
+
+ pages = drm_gem_get_pages(obj);
+ if (IS_ERR(pages)) {
+ DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
+ shmem->pages_use_count = 0;
+ return PTR_ERR(pages);
+ }
+
+ shmem->pages = pages;
+
+ return 0;
+}
+
+/*
+ * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This function makes sure that backing pages exists for the shmem GEM object
+ * and increases the use count.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
+{
+ int ret;
+
+ ret = mutex_lock_interruptible(&shmem->pages_lock);
+ if (ret)
+ return ret;
+ ret = drm_gem_shmem_get_pages_locked(shmem);
+ mutex_unlock(&shmem->pages_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_get_pages);
+
+static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
+{
+ struct drm_gem_object *obj = &shmem->base;
+
+ if (WARN_ON_ONCE(!shmem->pages_use_count))
+ return;
+
+ if (--shmem->pages_use_count > 0)
+ return;
+
+ drm_gem_put_pages(obj, shmem->pages,
+ shmem->pages_mark_dirty_on_put,
+ shmem->pages_mark_accessed_on_put);
+ shmem->pages = NULL;
+}
+
+/*
+ * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This function decreases the use count and puts the backing pages when use drops to zero.
+ */
+void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
+{
+ mutex_lock(&shmem->pages_lock);
+ drm_gem_shmem_put_pages_locked(shmem);
+ mutex_unlock(&shmem->pages_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_put_pages);
+
+/**
+ * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
+ * @obj: GEM object
+ *
+ * This function makes sure the backing pages are pinned in memory while the
+ * buffer is exported.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_pin(struct drm_gem_object *obj)
+{
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ return drm_gem_shmem_get_pages(shmem);
+}
+EXPORT_SYMBOL(drm_gem_shmem_pin);
+
+/**
+ * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
+ * @obj: GEM object
+ *
+ * This function removes the requirement that the backing pages are pinned in
+ * memory.
+ */
+void drm_gem_shmem_unpin(struct drm_gem_object *obj)
+{
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ drm_gem_shmem_put_pages(shmem);
+}
+EXPORT_SYMBOL(drm_gem_shmem_unpin);
+
+static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
+{
+ struct drm_gem_object *obj = &shmem->base;
+ int ret;
+
+ if (shmem->vmap_use_count++ > 0)
+ return shmem->vaddr;
+
+ ret = drm_gem_shmem_get_pages(shmem);
+ if (ret)
+ goto err_zero_use;
+
+ if (obj->import_attach)
+ shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
+ else
+ shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT, VM_MAP, PAGE_KERNEL);
+
+ if (!shmem->vaddr) {
+ DRM_DEBUG_KMS("Failed to vmap pages\n");
+ ret = -ENOMEM;
+ goto err_put_pages;
+ }
+
+ return shmem->vaddr;
+
+err_put_pages:
+ drm_gem_shmem_put_pages(shmem);
+err_zero_use:
+ shmem->vmap_use_count = 0;
+
+ return ERR_PTR(ret);
+}
+
+/*
+ * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This function makes sure that a virtual address exists for the buffer backing
+ * the shmem GEM object.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+void *drm_gem_shmem_vmap(struct drm_gem_object *obj)
+{
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+ void *vaddr;
+ int ret;
+
+ ret = mutex_lock_interruptible(&shmem->vmap_lock);
+ if (ret)
+ return ERR_PTR(ret);
+ vaddr = drm_gem_shmem_vmap_locked(shmem);
+ mutex_unlock(&shmem->vmap_lock);
+
+ return vaddr;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap);
+
+static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem)
+{
+ struct drm_gem_object *obj = &shmem->base;
+
+ if (WARN_ON_ONCE(!shmem->vmap_use_count))
+ return;
+
+ if (--shmem->vmap_use_count > 0)
+ return;
+
+ if (obj->import_attach)
+ dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
+ else
+ vunmap(shmem->vaddr);
+
+ shmem->vaddr = NULL;
+ drm_gem_shmem_put_pages(shmem);
+}
+
+/*
+ * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This function removes the virtual address when use count drops to zero.
+ */
+void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr)
+{
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ mutex_lock(&shmem->vmap_lock);
+ drm_gem_shmem_vunmap_locked(shmem);
+ mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap);
+
+static struct drm_gem_shmem_object *
+drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
+ struct drm_device *dev, size_t size,
+ uint32_t *handle)
+{
+ struct drm_gem_shmem_object *shmem;
+ int ret;
+
+ shmem = drm_gem_shmem_create(dev, size);
+ if (IS_ERR(shmem))
+ return shmem;
+
+ /*
+ * Allocate an id of idr table where the obj is registered
+ * and handle has the id what user can see.
+ */
+ ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
+ /* drop reference from allocate - handle holds it now. */
+ drm_gem_object_put_unlocked(&shmem->base);
+ if (ret)
+ return ERR_PTR(ret);
+
+ return shmem;
+}
+
+/**
+ * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
+ * @file: DRM file structure to create the dumb buffer for
+ * @dev: DRM device
+ * @args: IOCTL data
+ *
+ * This function computes the pitch of the dumb buffer and rounds it up to an
+ * integer number of bytes per pixel. Drivers for hardware that doesn't have
+ * any additional restrictions on the pitch can directly use this function as
+ * their &drm_driver.dumb_create callback.
+ *
+ * For hardware with additional restrictions, drivers can adjust the fields
+ * set up by userspace before calling into this function.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
+ struct drm_mode_create_dumb *args)
+{
+ u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+ struct drm_gem_shmem_object *shmem;
+
+ if (!args->pitch || !args->size) {
+ args->pitch = min_pitch;
+ args->size = args->pitch * args->height;
+ } else {
+ /* ensure sane minimum values */
+ if (args->pitch < min_pitch)
+ args->pitch = min_pitch;
+ if (args->size < args->pitch * args->height)
+ args->size = args->pitch * args->height;
+ }
+
+ shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
+
+ return PTR_ERR_OR_ZERO(shmem);
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
+
+static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct drm_gem_object *obj = vma->vm_private_data;
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+ loff_t num_pages = obj->size >> PAGE_SHIFT;
+ struct page *page;
+
+ if (vmf->pgoff > num_pages || WARN_ON_ONCE(!shmem->pages))
+ return VM_FAULT_SIGBUS;
+
+ page = shmem->pages[vmf->pgoff];
+
+ return vmf_insert_page(vma, vmf->address, page);
+}
+
+static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
+{
+ struct drm_gem_object *obj = vma->vm_private_data;
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+ int ret;
+
+ ret = drm_gem_shmem_get_pages(shmem);
+ WARN_ON_ONCE(ret != 0);
+
+ drm_gem_vm_open(vma);
+}
+
+static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
+{
+ struct drm_gem_object *obj = vma->vm_private_data;
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ drm_gem_shmem_put_pages(shmem);
+ drm_gem_vm_close(vma);
+}
+
+const struct vm_operations_struct drm_gem_shmem_vm_ops = {
+ .fault = drm_gem_shmem_fault,
+ .open = drm_gem_shmem_vm_open,
+ .close = drm_gem_shmem_vm_close,
+};
+EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
+
+/**
+ * drm_gem_shmem_mmap - Memory-map a shmem GEM object
+ * @filp: File object
+ * @vma: VMA for the area to be mapped
+ *
+ * This function implements an augmented version of the GEM DRM file mmap
+ * operation for shmem objects. Drivers which employ the shmem helpers should
+ * use this function as their &file_operations.mmap handler in the DRM device file's
+ * file_operations structure.
+ *
+ * Instead of directly referencing this function, drivers should use the
+ * DEFINE_DRM_GEM_SHMEM_FOPS() macro.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ struct drm_gem_shmem_object *shmem;
+ int ret;
+
+ ret = drm_gem_mmap(filp, vma);
+ if (ret)
+ return ret;
+
+ shmem = to_drm_gem_shmem_obj(vma->vm_private_data);
+
+ ret = drm_gem_shmem_get_pages(shmem);
+ if (ret) {
+ drm_gem_vm_close(vma);
+ return ret;
+ }
+
+ /* VM_PFNMAP was set by drm_gem_mmap() */
+ vma->vm_flags &= ~VM_PFNMAP;
+ vma->vm_flags |= VM_MIXEDMAP;
+
+ /* Remove the fake offset */
+ vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
+
+/**
+ * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
+ * @p: DRM printer
+ * @indent: Tab indentation level
+ * @obj: GEM object
+ */
+void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
+ const struct drm_gem_object *obj)
+{
+ const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
+ drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
+ drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
+}
+EXPORT_SYMBOL(drm_gem_shmem_print_info);
+
+/**
+ * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
+ * pages for a shmem GEM object
+ * @obj: GEM object
+ *
+ * This function exports a scatter/gather table suitable for PRIME usage by
+ * calling the standard DMA mapping API.
+ *
+ * Returns:
+ * A pointer to the scatter/gather table of pinned pages or NULL on failure.
+ */
+struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
+{
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
+
+/**
+ * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
+ * another driver's scatter/gather table of pinned pages
+ * @dev: Device to import into
+ * @attach: DMA-BUF attachment
+ * @sgt: Scatter/gather table of pinned pages
+ *
+ * This function imports a scatter/gather table exported via DMA-BUF by
+ * another driver. Drivers that use the shmem helpers should set this as their
+ * &drm_driver.gem_prime_import_sg_table callback.
+ *
+ * Returns:
+ * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
+ * error code on failure.
+ */
+struct drm_gem_object *
+drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
+ struct dma_buf_attachment *attach,
+ struct sg_table *sgt)
+{
+ size_t size = PAGE_ALIGN(attach->dmabuf->size);
+ size_t npages = size >> PAGE_SHIFT;
+ struct drm_gem_shmem_object *shmem;
+ int ret;
+
+ shmem = drm_gem_shmem_create(dev, size);
+ if (IS_ERR(shmem))
+ return ERR_CAST(shmem);
+
+ shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
+ if (!shmem->pages) {
+ ret = -ENOMEM;
+ goto err_free_gem;
+ }
+
+ ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
+ if (ret < 0)
+ goto err_free_array;
+
+ shmem->sgt = sgt;
+ shmem->pages_use_count = 1; /* Permanently pinned from our point of view */
+
+ DRM_DEBUG_PRIME("size = %zu\n", size);
+
+ return &shmem->base;
+
+err_free_array:
+ kvfree(shmem->pages);
+err_free_gem:
+ drm_gem_object_put_unlocked(&shmem->base);
+
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
new file mode 100644
index 000000000000..26b05e06407d
--- /dev/null
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -0,0 +1,153 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __DRM_GEM_SHMEM_HELPER_H__
+#define __DRM_GEM_SHMEM_HELPER_H__
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+
+#include <drm/drm_file.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_ioctl.h>
+#include <drm/drm_prime.h>
+
+struct dma_buf_attachment;
+struct drm_mode_create_dumb;
+struct drm_printer;
+struct sg_table;
+
+/**
+ * struct drm_gem_shmem_object - GEM object backed by shmem
+ */
+struct drm_gem_shmem_object {
+ /**
+ * @base: Base GEM object
+ */
+ struct drm_gem_object base;
+
+ /**
+ * @pages_lock: Protects the page table and use count
+ */
+ struct mutex pages_lock;
+
+ /**
+ * @pages: Page table
+ */
+ struct page **pages;
+
+ /**
+ * @pages_use_count:
+ *
+ * Reference count on the pages table.
+ * The pages are put when the count reaches zero.
+ */
+ unsigned int pages_use_count;
+
+ /**
+ * @pages_mark_dirty_on_put:
+ *
+ * Mark pages as dirty when they are put.
+ */
+ unsigned int pages_mark_dirty_on_put : 1;
+
+ /**
+ * @pages_mark_accessed_on_put:
+ *
+ * Mark pages as accessed when they are put.
+ */
+ unsigned int pages_mark_accessed_on_put : 1;
+
+ /**
+ * @sgt: Scatter/gather table for imported PRIME buffers
+ */
+ struct sg_table *sgt;
+
+ /**
+ * @vmap_lock: Protects the vmap address and use count
+ */
+ struct mutex vmap_lock;
+
+ /**
+ * @vaddr: Kernel virtual address of the backing memory
+ */
+ void *vaddr;
+
+ /**
+ * @vmap_use_count:
+ *
+ * Reference count on the virtual address.
+ * The address are un-mapped when the count reaches zero.
+ */
+ unsigned int vmap_use_count;
+};
+
+#define to_drm_gem_shmem_obj(obj) \
+ container_of(obj, struct drm_gem_shmem_object, base)
+
+/**
+ * DEFINE_DRM_GEM_SHMEM_FOPS() - Macro to generate file operations for shmem drivers
+ * @name: name for the generated structure
+ *
+ * This macro autogenerates a suitable &struct file_operations for shmem based
+ * drivers, which can be assigned to &drm_driver.fops. Note that this structure
+ * cannot be shared between drivers, because it contains a reference to the
+ * current module using THIS_MODULE.
+ *
+ * Note that the declaration is already marked as static - if you need a
+ * non-static version of this you're probably doing it wrong and will break the
+ * THIS_MODULE reference by accident.
+ */
+#define DEFINE_DRM_GEM_SHMEM_FOPS(name) \
+ static const struct file_operations name = {\
+ .owner = THIS_MODULE,\
+ .open = drm_open,\
+ .release = drm_release,\
+ .unlocked_ioctl = drm_ioctl,\
+ .compat_ioctl = drm_compat_ioctl,\
+ .poll = drm_poll,\
+ .read = drm_read,\
+ .llseek = noop_llseek,\
+ .mmap = drm_gem_shmem_mmap, \
+ }
+
+struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size);
+void drm_gem_shmem_free_object(struct drm_gem_object *obj);
+
+int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem);
+void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
+int drm_gem_shmem_pin(struct drm_gem_object *obj);
+void drm_gem_shmem_unpin(struct drm_gem_object *obj);
+void *drm_gem_shmem_vmap(struct drm_gem_object *obj);
+void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr);
+
+int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
+ struct drm_mode_create_dumb *args);
+
+int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma);
+
+extern const struct vm_operations_struct drm_gem_shmem_vm_ops;
+
+void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
+ const struct drm_gem_object *obj);
+
+struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj);
+struct drm_gem_object *
+drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
+ struct dma_buf_attachment *attach,
+ struct sg_table *sgt);
+
+/**
+ * DRM_GEM_SHMEM_DRIVER_OPS - Default shmem GEM operations
+ *
+ * This macro provides a shortcut for setting the shmem GEM operations in
+ * the &drm_driver structure.
+ */
+#define DRM_GEM_SHMEM_DRIVER_OPS \
+ .prime_handle_to_fd = drm_gem_prime_handle_to_fd, \
+ .prime_fd_to_handle = drm_gem_prime_fd_to_handle, \
+ .gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table, \
+ .gem_prime_mmap = drm_gem_prime_mmap, \
+ .dumb_create = drm_gem_shmem_dumb_create
+
+#endif /* __DRM_GEM_SHMEM_HELPER_H__ */
--
2.19.1
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