drm/vgem: implement virtual GEM

This patch implements the virtual GEM driver with PRIME sharing which
allows vgem to import a gem object from other drivers for the purpose
of mmap-ing them to userspace. The mmap is done using the mmap
operation exported by other drivers.

v2: remove platform_device and do not attach to dma bufs
v3: use drm helpers for get/put pages
v4: correct dumb create pitch

Reviewed-by: Rob Clark <robdclark@gmail.com> (v3)
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org> (v3)
Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Zach Reizner <zachr@google.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/Kconfig

@@ -165,6 +165,15 @@ config DRM_SAVAGE
 	  Choose this option if you have a Savage3D/4/SuperSavage/Pro/Twister
 	  chipset. If M is selected the module will be called savage.
 
+config DRM_VGEM
+	tristate "Virtual GEM provider"
+	depends on DRM
+	help
+	  Choose this option to get a virtual graphics memory manager,
+	  as used by Mesa's software renderer for enhanced performance.
+	  If M is selected the module will be called vgem.
+
+
 source "drivers/gpu/drm/exynos/Kconfig"
 
 source "drivers/gpu/drm/rockchip/Kconfig"

drivers/gpu/drm/Makefile

@@ -48,6 +48,7 @@ obj-$(CONFIG_DRM_SIS)   += sis/
 obj-$(CONFIG_DRM_SAVAGE)+= savage/
 obj-$(CONFIG_DRM_VMWGFX)+= vmwgfx/
 obj-$(CONFIG_DRM_VIA)	+=via/
+obj-$(CONFIG_DRM_VGEM)	+= vgem/
 obj-$(CONFIG_DRM_NOUVEAU) +=nouveau/
 obj-$(CONFIG_DRM_EXYNOS) +=exynos/
 obj-$(CONFIG_DRM_ROCKCHIP) +=rockchip/

drivers/gpu/drm/vgem/Makefile

@@ -0,0 +1,4 @@
+ccflags-y := -Iinclude/drm
+vgem-y := vgem_drv.o vgem_dma_buf.o
+
+obj-$(CONFIG_DRM_VGEM)	+= vgem.o

drivers/gpu/drm/vgem/vgem_dma_buf.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ * Copyright © 2014 The Chromium OS Authors
+ *
+ * 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:
+ *    Ben Widawsky <ben@bwidawsk.net>
+ *
+ */
+
+#include <linux/dma-buf.h>
+#include "vgem_drv.h"
+
+struct sg_table *vgem_gem_prime_get_sg_table(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	BUG_ON(obj->pages == NULL);
+
+	return drm_prime_pages_to_sg(obj->pages, obj->base.size / PAGE_SIZE);
+}
+
+int vgem_gem_prime_pin(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	return vgem_gem_get_pages(obj);
+}
+
+void vgem_gem_prime_unpin(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	vgem_gem_put_pages(obj);
+}
+
+void *vgem_gem_prime_vmap(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	BUG_ON(obj->pages == NULL);
+
+	return vmap(obj->pages, obj->base.size / PAGE_SIZE, 0, PAGE_KERNEL);
+}
+
+void vgem_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
+{
+	vunmap(vaddr);
+}
+
+struct drm_gem_object *vgem_gem_prime_import(struct drm_device *dev,
+					     struct dma_buf *dma_buf)
+{
+	struct drm_vgem_gem_object *obj = NULL;
+	int ret;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (obj == NULL) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	ret = drm_gem_object_init(dev, &obj->base, dma_buf->size);
+	if (ret) {
+		ret = -ENOMEM;
+		goto fail_free;
+	}
+
+	get_dma_buf(dma_buf);
+
+	obj->base.dma_buf = dma_buf;
+	obj->use_dma_buf = true;
+
+	return &obj->base;
+
+fail_free:
+	kfree(obj);
+fail:
+	return ERR_PTR(ret);
+}