drm/udl: add support to export a handle to a FD on UDL.

Only importing an FD to a handle is currently supported on UDL,
but the exporting functionality is equally useful.

Signed-off-by: Haixia Shi <[e-mail]>
Reviewed-by: Stéphane Marchesin <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/udl/Makefile

···
 
 ccflags-y := -Iinclude/drm
 
-udl-y := udl_drv.o udl_modeset.o udl_connector.o udl_encoder.o udl_main.o udl_fb.o udl_transfer.o udl_gem.o
+udl-y := udl_drv.o udl_modeset.o udl_connector.o udl_encoder.o udl_main.o udl_fb.o udl_transfer.o udl_gem.o udl_dmabuf.o
 
 obj-$(CONFIG_DRM_UDL) := udl.o

drivers/gpu/drm/udl/udl_dmabuf.c

···
+/*
+ * udl_dmabuf.c
+ *
+ * Copyright (c) 2014 The Chromium OS Authors
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <drm/drmP.h>
+#include "udl_drv.h"
+#include <linux/shmem_fs.h>
+#include <linux/dma-buf.h>
+
+struct udl_drm_dmabuf_attachment {
+	struct sg_table sgt;
+	enum dma_data_direction dir;
+	bool is_mapped;
+};
+
+static int udl_attach_dma_buf(struct dma_buf *dmabuf,
+			      struct device *dev,
+			      struct dma_buf_attachment *attach)
+{
+	struct udl_drm_dmabuf_attachment *udl_attach;
+
+	DRM_DEBUG_PRIME("[DEV:%s] size:%zd\n", dev_name(attach->dev),
+			attach->dmabuf->size);
+
+	udl_attach = kzalloc(sizeof(*udl_attach), GFP_KERNEL);
+	if (!udl_attach)
+		return -ENOMEM;
+
+	udl_attach->dir = DMA_NONE;
+	attach->priv = udl_attach;
+
+	return 0;
+}
+
+static void udl_detach_dma_buf(struct dma_buf *dmabuf,
+			       struct dma_buf_attachment *attach)
+{
+	struct udl_drm_dmabuf_attachment *udl_attach = attach->priv;
+	struct sg_table *sgt;
+
+	if (!udl_attach)
+		return;
+
+	DRM_DEBUG_PRIME("[DEV:%s] size:%zd\n", dev_name(attach->dev),
+			attach->dmabuf->size);
+
+	sgt = &udl_attach->sgt;
+
+	if (udl_attach->dir != DMA_NONE)
+		dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
+				udl_attach->dir);
+
+	sg_free_table(sgt);
+	kfree(udl_attach);
+	attach->priv = NULL;
+}
+
+static struct sg_table *udl_map_dma_buf(struct dma_buf_attachment *attach,
+					enum dma_data_direction dir)
+{
+	struct udl_drm_dmabuf_attachment *udl_attach = attach->priv;
+	struct udl_gem_object *obj = to_udl_bo(attach->dmabuf->priv);
+	struct drm_device *dev = obj->base.dev;
+	struct scatterlist *rd, *wr;
+	struct sg_table *sgt = NULL;
+	unsigned int i;
+	int page_count;
+	int nents, ret;
+
+	DRM_DEBUG_PRIME("[DEV:%s] size:%zd dir=%d\n", dev_name(attach->dev),
+			attach->dmabuf->size, dir);
+
+	/* just return current sgt if already requested. */
+	if (udl_attach->dir == dir && udl_attach->is_mapped)
+		return &udl_attach->sgt;
+
+	if (!obj->pages) {
+		DRM_ERROR("pages is null.\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	page_count = obj->base.size / PAGE_SIZE;
+	obj->sg = drm_prime_pages_to_sg(obj->pages, page_count);
+	if (!obj->sg) {
+		DRM_ERROR("sg is null.\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	sgt = &udl_attach->sgt;
+
+	ret = sg_alloc_table(sgt, obj->sg->orig_nents, GFP_KERNEL);
+	if (ret) {
+		DRM_ERROR("failed to alloc sgt.\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mutex_lock(&dev->struct_mutex);
+
+	rd = obj->sg->sgl;
+	wr = sgt->sgl;
+	for (i = 0; i < sgt->orig_nents; ++i) {
+		sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
+		rd = sg_next(rd);
+		wr = sg_next(wr);
+	}
+
+	if (dir != DMA_NONE) {
+		nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir);
+		if (!nents) {
+			DRM_ERROR("failed to map sgl with iommu.\n");
+			sg_free_table(sgt);
+			sgt = ERR_PTR(-EIO);
+			goto err_unlock;
+		}
+	}
+
+	udl_attach->is_mapped = true;
+	udl_attach->dir = dir;
+	attach->priv = udl_attach;
+
+err_unlock:
+	mutex_unlock(&dev->struct_mutex);
+	return sgt;
+}
+
+static void udl_unmap_dma_buf(struct dma_buf_attachment *attach,
+			      struct sg_table *sgt,
+			      enum dma_data_direction dir)
+{
+	/* Nothing to do. */
+	DRM_DEBUG_PRIME("[DEV:%s] size:%zd dir:%d\n", dev_name(attach->dev),
+			attach->dmabuf->size, dir);
+}
+
+static void *udl_dmabuf_kmap(struct dma_buf *dma_buf, unsigned long page_num)
+{
+	/* TODO */
+
+	return NULL;
+}
+
+static void *udl_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
+				    unsigned long page_num)
+{
+	/* TODO */
+
+	return NULL;
+}
+
+static void udl_dmabuf_kunmap(struct dma_buf *dma_buf,
+			      unsigned long page_num, void *addr)
+{
+	/* TODO */
+}
+
+static void udl_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
+				     unsigned long page_num,
+				     void *addr)
+{
+	/* TODO */
+}
+
+static int udl_dmabuf_mmap(struct dma_buf *dma_buf,
+			   struct vm_area_struct *vma)
+{
+	/* TODO */
+
+	return -EINVAL;
+}
+
+static struct dma_buf_ops udl_dmabuf_ops = {
+	.attach			= udl_attach_dma_buf,
+	.detach			= udl_detach_dma_buf,
+	.map_dma_buf		= udl_map_dma_buf,
+	.unmap_dma_buf		= udl_unmap_dma_buf,
+	.kmap			= udl_dmabuf_kmap,
+	.kmap_atomic		= udl_dmabuf_kmap_atomic,
+	.kunmap			= udl_dmabuf_kunmap,
+	.kunmap_atomic		= udl_dmabuf_kunmap_atomic,
+	.mmap			= udl_dmabuf_mmap,
+	.release		= drm_gem_dmabuf_release,
+};
+
+struct dma_buf *udl_gem_prime_export(struct drm_device *dev,
+				     struct drm_gem_object *obj, int flags)
+{
+	return dma_buf_export(obj, &udl_dmabuf_ops, obj->size, flags, NULL);
+}
+
+static int udl_prime_create(struct drm_device *dev,
+			    size_t size,
+			    struct sg_table *sg,
+			    struct udl_gem_object **obj_p)
+{
+	struct udl_gem_object *obj;
+	int npages;
+
+	npages = size / PAGE_SIZE;
+
+	*obj_p = NULL;
+	obj = udl_gem_alloc_object(dev, npages * PAGE_SIZE);
+	if (!obj)
+		return -ENOMEM;
+
+	obj->sg = sg;
+	obj->pages = drm_malloc_ab(npages, sizeof(struct page *));
+	if (obj->pages == NULL) {
+		DRM_ERROR("obj pages is NULL %d\n", npages);
+		return -ENOMEM;
+	}
+
+	drm_prime_sg_to_page_addr_arrays(sg, obj->pages, NULL, npages);
+
+	*obj_p = obj;
+	return 0;
+}
+
+struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
+				struct dma_buf *dma_buf)
+{
+	struct dma_buf_attachment *attach;
+	struct sg_table *sg;
+	struct udl_gem_object *uobj;
+	int ret;
+
+	/* need to attach */
+	get_device(dev->dev);
+	attach = dma_buf_attach(dma_buf, dev->dev);
+	if (IS_ERR(attach)) {
+		put_device(dev->dev);
+		return ERR_CAST(attach);
+	}
+
+	get_dma_buf(dma_buf);
+
+	sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sg)) {
+		ret = PTR_ERR(sg);
+		goto fail_detach;
+	}
+
+	ret = udl_prime_create(dev, dma_buf->size, sg, &uobj);
+	if (ret)
+		goto fail_unmap;
+
+	uobj->base.import_attach = attach;
+	uobj->flags = UDL_BO_WC;
+
+	return &uobj->base;
+
+fail_unmap:
+	dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
+fail_detach:
+	dma_buf_detach(dma_buf, attach);
+	dma_buf_put(dma_buf);
+	put_device(dev->dev);
+	return ERR_PTR(ret);
+}

drivers/gpu/drm/udl/udl_drv.c

···
 	.dumb_destroy = drm_gem_dumb_destroy,
 	.fops = &udl_driver_fops,
 
+	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
+	.gem_prime_export = udl_gem_prime_export,
 	.gem_prime_import = udl_gem_prime_import,
 
 	.name = DRIVER_NAME,

drivers/gpu/drm/udl/udl_drv.h

···
 void udl_gem_free_object(struct drm_gem_object *gem_obj);
 struct udl_gem_object *udl_gem_alloc_object(struct drm_device *dev,
 					    size_t size);
+struct dma_buf *udl_gem_prime_export(struct drm_device *dev,
+				     struct drm_gem_object *obj, int flags);
 struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
 				struct dma_buf *dma_buf);
 

drivers/gpu/drm/udl/udl_gem.c

···
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
 }
-
-static int udl_prime_create(struct drm_device *dev,
-			    size_t size,
-			    struct sg_table *sg,
-			    struct udl_gem_object **obj_p)
-{
-	struct udl_gem_object *obj;
-	int npages;
-
-	npages = size / PAGE_SIZE;
-
-	*obj_p = NULL;
-	obj = udl_gem_alloc_object(dev, npages * PAGE_SIZE);
-	if (!obj)
-		return -ENOMEM;
-
-	obj->sg = sg;
-	obj->pages = drm_malloc_ab(npages, sizeof(struct page *));
-	if (obj->pages == NULL) {
-		DRM_ERROR("obj pages is NULL %d\n", npages);
-		return -ENOMEM;
-	}
-
-	drm_prime_sg_to_page_addr_arrays(sg, obj->pages, NULL, npages);
-
-	*obj_p = obj;
-	return 0;
-}
-
-struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
-				struct dma_buf *dma_buf)
-{
-	struct dma_buf_attachment *attach;
-	struct sg_table *sg;
-	struct udl_gem_object *uobj;
-	int ret;
-
-	/* need to attach */
-	get_device(dev->dev);
-	attach = dma_buf_attach(dma_buf, dev->dev);
-	if (IS_ERR(attach)) {
-		put_device(dev->dev);
-		return ERR_CAST(attach);
-	}
-
-	get_dma_buf(dma_buf);
-
-	sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
-	if (IS_ERR(sg)) {
-		ret = PTR_ERR(sg);
-		goto fail_detach;
-	}
-
-	ret = udl_prime_create(dev, dma_buf->size, sg, &uobj);
-	if (ret) {
-		goto fail_unmap;
-	}
-
-	uobj->base.import_attach = attach;
-	uobj->flags = UDL_BO_WC;
-
-	return &uobj->base;
-
-fail_unmap:
-	dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
-fail_detach:
-	dma_buf_detach(dma_buf, attach);
-	dma_buf_put(dma_buf);
-	put_device(dev->dev);
-	return ERR_PTR(ret);
-}