i915: add dmabuf/prime buffer sharing support.

This adds handle->fd and fd->handle support to i915, this is to allow
for offloading of rendering in one direction and outputs in the other.

v2 from Daniel Vetter:
- fixup conflicts with the prepare/finish gtt prep work.
- implement ppgtt binding support.

Note that we have squat i-g-t testcoverage for any of the lifetime and
access rules dma_buf/prime support brings along. And there are quite a
few intricate situations here.

Also note that the integration with the existing code is a bit
hackish, especially around get_gtt_pages and put_gtt_pages. It imo
would be easier with the prep code from Chris Wilson's unbound series,
but that is for 3.6.

Also note that I didn't bother to put the new prepare/finish gtt hooks
to good use by moving the dma_buf_map/unmap_attachment calls in there
(like we've originally planned for).

Last but not least this patch is only compile-tested, but I've changed
very little compared to Dave Airlie's version. So there's a decent
chance v2 on drm-next works as well as v1 on 3.4-rc.

v3: Right when I've hit sent I've noticed that I've screwed up one
obj->sg_list (for dmar support) and obj->sg_table (for prime support)
disdinction. We should be able to merge these 2 paths, but that's
material for another patch.

v4: fix the error reporting bugs pointed out by ickle.

v5: fix another error, and stop non-gtt mmaps on shared objects
stop pread/pwrite on imported objects, add fake kmap

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 171 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
new file mode 100644
index 000000000000..4f8e142604ab
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -0,0 +1,171 @@
+/*
+ * Copyright 2012 Red Hat Inc
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *	Dave Airlie <airlied@redhat.com>
+ */
+#include "drmP.h"
+#include "i915_drv.h"
+#include <linux/dma-buf.h>
+
+struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachment,
+				      enum dma_data_direction dir)
+{
+	struct drm_i915_gem_object *obj = attachment->dmabuf->priv;
+	struct drm_device *dev = obj->base.dev;
+	int npages = obj->base.size / PAGE_SIZE;
+	struct sg_table *sg = NULL;
+	int ret;
+	int nents;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!obj->pages) {
+		ret = i915_gem_object_get_pages_gtt(obj, __GFP_NORETRY | __GFP_NOWARN);
+		if (ret)
+			goto out;
+	}
+
+	/* link the pages into an SG then map the sg */
+	sg = drm_prime_pages_to_sg(obj->pages, npages);
+	nents = dma_map_sg(attachment->dev, sg->sgl, sg->nents, dir);
+out:
+	mutex_unlock(&dev->struct_mutex);
+	return sg;
+}
+
+void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
+			    struct sg_table *sg, enum dma_data_direction dir)
+{
+	dma_unmap_sg(attachment->dev, sg->sgl, sg->nents, dir);
+	sg_free_table(sg);
+	kfree(sg);
+}
+
+void i915_gem_dmabuf_release(struct dma_buf *dma_buf)
+{
+	struct drm_i915_gem_object *obj = dma_buf->priv;
+
+	if (obj->base.export_dma_buf == dma_buf) {
+		/* drop the reference on the export fd holds */
+		obj->base.export_dma_buf = NULL;
+		drm_gem_object_unreference_unlocked(&obj->base);
+	}
+}
+
+static void *i915_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf, unsigned long page_num)
+{
+	return NULL;
+}
+
+static void i915_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf, unsigned long page_num, void *addr)
+{
+
+}
+static void *i915_gem_dmabuf_kmap(struct dma_buf *dma_buf, unsigned long page_num)
+{
+	return NULL;
+}
+
+static void i915_gem_dmabuf_kunmap(struct dma_buf *dma_buf, unsigned long page_num, void *addr)
+{
+
+}
+
+struct dma_buf_ops i915_dmabuf_ops =  {
+	.map_dma_buf = i915_gem_map_dma_buf,
+	.unmap_dma_buf = i915_gem_unmap_dma_buf,
+	.release = i915_gem_dmabuf_release,
+	.kmap = i915_gem_dmabuf_kmap,
+	.kmap_atomic = i915_gem_dmabuf_kmap_atomic,
+	.kunmap = i915_gem_dmabuf_kunmap,
+	.kunmap_atomic = i915_gem_dmabuf_kunmap_atomic,
+};
+
+struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
+				struct drm_gem_object *gem_obj, int flags)
+{
+	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
+
+	return dma_buf_export(obj, &i915_dmabuf_ops,
+						  obj->base.size, 0600);
+}
+
+struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
+				struct dma_buf *dma_buf)
+{
+	struct dma_buf_attachment *attach;
+	struct sg_table *sg;
+	struct drm_i915_gem_object *obj;
+	int npages;
+	int size;
+	int ret;
+
+	/* is this one of own objects? */
+	if (dma_buf->ops == &i915_dmabuf_ops) {
+		obj = dma_buf->priv;
+		/* is it from our device? */
+		if (obj->base.dev == dev) {
+			drm_gem_object_reference(&obj->base);
+			return &obj->base;
+		}
+	}
+
+	/* need to attach */
+	attach = dma_buf_attach(dma_buf, dev->dev);
+	if (IS_ERR(attach))
+		return ERR_CAST(attach);
+
+	sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sg)) {
+		ret = PTR_ERR(sg);
+		goto fail_detach;
+	}
+
+	size = dma_buf->size;
+	npages = size / PAGE_SIZE;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (obj == NULL) {
+		ret = -ENOMEM;
+		goto fail_unmap;
+	}
+
+	ret = drm_gem_private_object_init(dev, &obj->base, size);
+	if (ret) {
+		kfree(obj);
+		goto fail_unmap;
+	}
+
+	obj->sg_table = sg;
+	obj->base.import_attach = attach;
+
+	return &obj->base;
+
+fail_unmap:
+	dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
+fail_detach:
+	dma_buf_detach(dma_buf, attach);
+	return ERR_PTR(ret);
+}