[PATCH v3] drm/i915: Implement dma-buf mmap() for userspace access

[Ander Conselvan de Oliveira <conselvan2@gmail.com>]

From: Rob Bradford <rob@linux.intel.com>

The aim is that this is functionally equivalent to using the
I915_GEM_MMAP ioctl.

v2: Add aperture check limit, limit to SNB+ and improve error handling.

v3 (anderco): Map without using the GTT.

Signed-off-by: Rob Bradford <rob@linux.intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_dmabuf.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index 580aa42..2d31fca 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -193,7 +193,24 @@ static void i915_gem_dmabuf_kunmap(struct dma_buf *dma_buf, unsigned long page_n
 
 static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
 {
-	return -EINVAL;
+	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
+	struct drm_device *dev = obj->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int ret;
+
+	if (INTEL_INFO(dev)->gen < 6)
+		return -EINVAL;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ret;
+
+	ret = obj->base.filp->f_op->mmap(obj->base.filp, vma);
+	fput(vma->vm_file);
+	vma->vm_file = get_file(obj->base.filp);
+
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
 }
 
 static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t length, enum dma_data_direction direction)
-- 
1.8.3.2