gbm: Add map/unmap functions

This adds map and unmap functions to GBM utilizing the DRIimage extension
mapImage/unmapImage functions or existing internal mapping for dumb
buffers. Unlike prior attempts, this version provides a region to map and
usage flags for the mapping. The operation follows the same semantics as
the gallium transfer_map() function.

This was tested with GBM based gralloc on Android.

Signed-off-by: Rob Herring <[email protected]>
[Emil Velikov: drop no longer relevant hunk from commit message.]
Reviewed-by: Emil Velikov <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

3 files changed, 94 insertions, 0 deletions

diff --git a/src/gbm/main/gbm.c b/src/gbm/main/gbm.c
index c046b1ad7c8..b0cab5129a1 100644
--- a/src/gbm/main/gbm.c
+++ b/src/gbm/main/gbm.c
@@ -386,6 +386,59 @@ gbm_bo_import(struct gbm_device *gbm,
 }
 
 /**
+ * Map a region of a gbm buffer object for cpu access
+ *
+ * This function maps a region of a gbm bo for cpu read and/or write
+ * access.
+ *
+ * \param bo The buffer object
+ * \param x The X (top left origin) starting position of the mapped region for
+ * the buffer
+ * \param y The Y (top left origin) starting position of the mapped region for
+ * the buffer
+ * \param width The width of the mapped region for the buffer
+ * \param height The height of the mapped region for the buffer
+ * \param flags The union of the GBM_BO_TRANSFER_* flags for this buffer
+ * \param stride Ptr for returned stride in bytes of the mapped region
+ * \param map_data Returned opaque ptr for the mapped region
+ *
+ * \return Address of the mapped buffer that should be unmapped with
+ * gbm_bo_unmap() when no longer needed. On error, %NULL is returned
+ * and errno is set.
+ *
+ * \sa enum gbm_bo_transfer_flags for the list of flags
+ */
+GBM_EXPORT void *
+gbm_bo_map(struct gbm_bo *bo,
+              uint32_t x, uint32_t y,
+              uint32_t width, uint32_t height,
+              uint32_t flags, uint32_t *stride, void **map_data)
+{
+   if (!bo || width == 0 || height == 0 || !stride || !map_data) {
+      errno = EINVAL;
+      return NULL;
+   }
+
+   return bo->gbm->bo_map(bo, x, y, width, height,
+                          flags, stride, map_data);
+}
+
+/**
+ * Unmap a previously mapped region of a gbm buffer object
+ *
+ * This function unmaps a region of a gbm bo for cpu read and/or write
+ * access.
+ *
+ * \param bo The buffer object
+ * \param map_data opaque ptr returned from prior gbm_bo_map
+ */
+GBM_EXPORT void
+gbm_bo_unmap(struct gbm_bo *bo, void *map_data)
+{
+   bo->gbm->bo_unmap(bo, map_data);
+}
+
+/**
  * Allocate a surface object
  *
  * \param gbm The gbm device returned from gbm_create_device()
diff --git a/src/gbm/main/gbm.h b/src/gbm/main/gbm.h
index 63d9a9edfd6..8a2f2a6a8cc 100644
--- a/src/gbm/main/gbm.h
+++ b/src/gbm/main/gbm.h
@@ -253,6 +253,41 @@ struct gbm_bo *
 gbm_bo_import(struct gbm_device *gbm, uint32_t type,
               void *buffer, uint32_t usage);
 
+/**
+ * Flags to indicate the type of mapping for the buffer - these are
+ * passed into gbm_bo_map(). The caller must set the union of all the
+ * flags that are appropriate.
+ *
+ * These flags are independent of the GBM_BO_USE_* creation flags. However,
+ * mapping the buffer may require copying to/from a staging buffer.
+ *
+ * See also: pipe_transfer_usage
+ */
+enum gbm_bo_transfer_flags {
+   /**
+    * Buffer contents read back (or accessed directly) at transfer
+    * create time.
+    */
+   GBM_BO_TRANSFER_READ       = (1 << 0),
+   /**
+    * Buffer contents will be written back at unmap time
+    * (or modified as a result of being accessed directly).
+    */
+   GBM_BO_TRANSFER_WRITE      = (1 << 1),
+   /**
+    * Read/modify/write
+    */
+   GBM_BO_TRANSFER_READ_WRITE = (GBM_BO_TRANSFER_READ | GBM_BO_TRANSFER_WRITE),
+};
+
+void *
+gbm_bo_map(struct gbm_bo *bo,
+           uint32_t x, uint32_t y, uint32_t width, uint32_t height,
+           uint32_t flags, uint32_t *stride, void **map_data);
+
+void
+gbm_bo_unmap(struct gbm_bo *bo, void *map_data);
+
 uint32_t
 gbm_bo_get_width(struct gbm_bo *bo);
 
diff --git a/src/gbm/main/gbmint.h b/src/gbm/main/gbmint.h
index 155eb12b06b..914e2c1749a 100644
--- a/src/gbm/main/gbmint.h
+++ b/src/gbm/main/gbmint.h
@@ -68,6 +68,12 @@ struct gbm_device {
                                uint32_t usage);
    struct gbm_bo *(*bo_import)(struct gbm_device *gbm, uint32_t type,
                                void *buffer, uint32_t usage);
+   void *(*bo_map)(struct gbm_bo *bo,
+                               uint32_t x, uint32_t y,
+                               uint32_t width, uint32_t height,
+                               uint32_t flags, uint32_t *stride,
+                               void **map_data);
+   void (*bo_unmap)(struct gbm_bo *bo, void *map_data);
    int (*bo_write)(struct gbm_bo *bo, const void *buf, size_t data);
    int (*bo_get_fd)(struct gbm_bo *bo);
    void (*bo_destroy)(struct gbm_bo *bo);