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 <robh@kernel.org>
[Emil Velikov: drop no longer relevant hunk from commit message.]
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/gbm/Makefile.am

@@ -41,10 +41,12 @@ libgbm_la_SOURCES += \
 
 AM_CFLAGS += \
 	-DDEFAULT_DRIVER_DIR='"$(DRI_DRIVER_SEARCH_DIR)"' \
-	$(LIBDRM_CFLAGS)
+	$(LIBDRM_CFLAGS) \
+	$(PTHREADSTUBS_CFLAGS)
 
 libgbm_la_LIBADD += \
-	$(LIBDRM_LIBS)
+	$(LIBDRM_LIBS) \
+	$(PTHREADSTUBS_LIBS)
 endif
 
 TESTS = gbm-symbols-check

src/gbm/backends/dri/gbm_dri.c

@@ -32,6 +32,7 @@
 #include <string.h>
 #include <errno.h>
 #include <limits.h>
+#include <assert.h>
 
 #include <sys/types.h>
 #include <unistd.h>
@@ -924,6 +925,60 @@ failed:
    return NULL;
 }
 
+static void *
+gbm_dri_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)
+{
+   struct gbm_dri_device *dri = gbm_dri_device(_bo->gbm);
+   struct gbm_dri_bo *bo = gbm_dri_bo(_bo);
+
+   /* If it's a dumb buffer, we already have a mapping */
+   if (bo->map) {
+      *map_data = (char *)bo->map + (bo->base.base.stride * y) + (x * 4);
+      *stride = bo->base.base.stride;
+      return *map_data;
+   }
+
+   if (!dri->image || dri->image->base.version < 12) {
+      errno = ENOSYS;
+      return NULL;
+   }
+
+   mtx_lock(&dri->mutex);
+   if (!dri->context)
+      dri->context = dri->dri2->createNewContext(dri->screen, NULL,
+                                                 NULL, NULL);
+   assert(dri->context);
+   mtx_unlock(&dri->mutex);
+
+   /* GBM flags and DRI flags are the same, so just pass them on */
+   return dri->image->mapImage(dri->context, bo->image, x, y,
+                               width, height, flags, (int *)stride,
+                               map_data);
+}
+
+static void
+gbm_dri_bo_unmap(struct gbm_bo *_bo, void *map_data)
+{
+   struct gbm_dri_device *dri = gbm_dri_device(_bo->gbm);
+   struct gbm_dri_bo *bo = gbm_dri_bo(_bo);
+
+   /* Check if it's a dumb buffer and check the pointer is in range */
+   if (bo->map) {
+      assert(map_data >= bo->map);
+      assert(map_data < (bo->map + bo->size));
+      return;
+   }
+
+   if (!dri->context || !dri->image || dri->image->base.version < 12)
+      return;
+
+   dri->image->unmapImage(dri->context, bo->image, map_data);
+}
+
+
 static struct gbm_surface *
 gbm_dri_surface_create(struct gbm_device *gbm,
                        uint32_t width, uint32_t height,
@@ -958,6 +1013,9 @@ dri_destroy(struct gbm_device *gbm)
    struct gbm_dri_device *dri = gbm_dri_device(gbm);
    unsigned i;
 
+   if (dri->context)
+      dri->core->destroyContext(dri->context);
+
    dri->core->destroyScreen(dri->screen);
    for (i = 0; dri->driver_configs[i]; i++)
       free((__DRIconfig *) dri->driver_configs[i]);
@@ -981,6 +1039,8 @@ dri_device_create(int fd)
    dri->base.base.fd = fd;
    dri->base.base.bo_create = gbm_dri_bo_create;
    dri->base.base.bo_import = gbm_dri_bo_import;
+   dri->base.base.bo_map = gbm_dri_bo_map;
+   dri->base.base.bo_unmap = gbm_dri_bo_unmap;
    dri->base.base.is_format_supported = gbm_dri_is_format_supported;
    dri->base.base.bo_write = gbm_dri_bo_write;
    dri->base.base.bo_get_fd = gbm_dri_bo_get_fd;
@@ -992,6 +1052,8 @@ dri_device_create(int fd)
    dri->base.type = GBM_DRM_DRIVER_TYPE_DRI;
    dri->base.base.name = "drm";
 
+   mtx_init(&dri->mutex, mtx_plain);
+
    force_sw = getenv("GBM_ALWAYS_SOFTWARE") != NULL;
    if (!force_sw) {
       ret = dri_screen_create(dri);

src/gbm/backends/dri/gbm_driint.h

@@ -30,6 +30,7 @@
 
 #include <sys/mman.h>
 #include "gbmint.h"
+#include "c11/threads.h"
 
 #include "common_drm.h"
 
@@ -45,6 +46,8 @@ struct gbm_dri_device {
    void *driver;
 
    __DRIscreen *screen;
+   __DRIcontext *context;
+   mtx_t mutex;
 
    const __DRIcoreExtension   *core;
    const __DRIdri2Extension   *dri2;

src/gbm/gbm-symbols-check

@@ -9,6 +9,8 @@ gbm_device_destroy
 gbm_create_device
 gbm_bo_create
 gbm_bo_import
+gbm_bo_map
+gbm_bo_unmap
 gbm_bo_get_width
 gbm_bo_get_height
 gbm_bo_get_stride

src/gbm/main/gbm.c

@@ -385,6 +385,59 @@ gbm_bo_import(struct gbm_device *gbm,
    return gbm->bo_import(gbm, type, buffer, usage);
 }
 
+/**
+ * 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
  *

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);
 

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);