# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1708472035 -3600
# Node ID 200859fe60d963f5c0f26d3ff027390e9878e87d
# Parent  b60c8cf438402842e13ef38bc4bb94aaa1c2dc0e
Exposed DMA space creation as a separate function.

diff -r b60c8cf43840 -r 200859fe60d9 pkg/devices/util/include/dma.h
--- a/pkg/devices/util/include/dma.h	Sun Feb 18 22:45:07 2024 +0100
+++ b/pkg/devices/util/include/dma.h	Wed Feb 21 00:33:55 2024 +0100
@@ -37,4 +37,9 @@
 
 long get_dma_region(unsigned long size, int align, struct dma_region *region);
 
+long get_dma_region_for_space(unsigned long size, int align, l4_cap_idx_t dma,
+                              struct dma_region *region);
+
+long get_dma_space(l4_cap_idx_t *dma);
+
 EXTERN_C_END
diff -r b60c8cf43840 -r 200859fe60d9 pkg/devices/util/src/dma.cc
--- a/pkg/devices/util/src/dma.cc	Sun Feb 18 22:45:07 2024 +0100
+++ b/pkg/devices/util/src/dma.cc	Wed Feb 21 00:33:55 2024 +0100
@@ -36,32 +36,26 @@
 
 
 
-// Allocate a memory region of the given size for DMA.
-
-long get_dma_region(unsigned long size, int align, struct dma_region *region)
-{
-  // Memory allocation capabilities.
-
-  l4_cap_idx_t dma, vbus;
+// Obtain a DMA space to which memory regions may be associated.
 
-  region->size = 0;
-  region->align = 0;
-
-  // Obtain capabilities for the DMA region and the vbus.
-
-  dma = ipc_cap_alloc();
-
-  if (l4_is_invalid_cap(dma))
-    return -L4_ENOENT;
-
-  vbus = l4re_env_get_cap("vbus");
+long get_dma_space(l4_cap_idx_t *dma)
+{
+  l4_cap_idx_t vbus = l4re_env_get_cap("vbus");
 
   if (l4_is_invalid_cap(vbus))
     return -L4_ENOENT;
 
+  // Obtain capabilities for the DMA region and the vbus.
+
+  *dma = ipc_cap_alloc();
+
+  if (l4_is_invalid_cap(*dma))
+    return -L4_ENOENT;
+
   // Create the DMA space.
 
-  if (l4_error(l4_factory_create(l4re_env()->mem_alloc, L4RE_PROTO_DMA_SPACE, dma)))
+  if (l4_error(l4_factory_create(l4re_env()->mem_alloc, L4RE_PROTO_DMA_SPACE,
+                                 *dma)))
     return -L4_ENOMEM;
 
   // Find the DMA domain and assign the DMA space.
@@ -74,28 +68,39 @@
 
   if (l4vbus_assign_dma_domain(vbus, dma_resource.start,
                                L4VBUS_DMAD_BIND | L4VBUS_DMAD_L4RE_DMA_SPACE,
-                               dma))
+                               *dma))
     return -L4_ENOMEM;
 
+  return L4_EOK;
+}
+
+// Obtain a memory region associated with the given DMA space.
+
+long get_dma_region_for_space(unsigned long size, int align, l4_cap_idx_t dma,
+                              struct dma_region *region)
+{
   // Allocate memory at the given alignment.
 
   const l4_size_t alloc_flags = L4RE_MA_CONTINUOUS | L4RE_MA_PINNED;
   const l4re_rm_flags_t attach_flags = L4RE_RM_F_SEARCH_ADDR | L4RE_RM_F_RW;
 
-  // Map the allocated memory, obtaining a virtual address.
+  region->align = 0;
+  region->paddr = 0;
+  region->size = 0;
+  region->vaddr = 0;
 
-  region->vaddr = 0;
+  // Map the allocated memory, obtaining a virtual address.
 
   if (ipc_new_dataspace(size, alloc_flags, align, &region->mem))
     return -L4_ENOMEM;
 
-  if (ipc_attach_dataspace_align(region->mem, size, attach_flags, align, (void **) &region->vaddr))
+  if (ipc_attach_dataspace_align(region->mem, size, attach_flags, align,
+                                 (void **) &region->vaddr))
     return -L4_ENOMEM;
 
   // Obtain a physical address.
 
   l4_size_t size_out = size;
-  region->paddr = 0;
 
   if (l4re_dma_space_map(dma, region->mem | L4_CAP_FPAGE_RW, 0, &size_out, 0,
                          L4RE_DMA_SPACE_TO_DEVICE, &region->paddr))
@@ -103,11 +108,24 @@
 
   // Test the mapped region size.
 
-  if (size_out != size)
+  if (size_out < size)
     return -L4_ENOMEM;
 
+  region->align = align;
   region->size = size_out;
-  region->align = align;
 
   return L4_EOK;
 }
+
+// Obtain a memory region associated with its own DMA space.
+
+long get_dma_region(unsigned long size, int align, struct dma_region *region)
+{
+  l4_cap_idx_t dma;
+  long err = get_dma_space(&dma);
+
+  if (err)
+    return err;
+
+  return get_dma_region_for_space(size, align, dma, region);
+}