accel: method for getting accel memory domain

This will allow drivers to check if a task is using buffers from accel
domain.  This is just a helper, since the same can be achieved by
calling `spdk_memory_domain_get_first("SPDK_ACCEL_DMA_DEVICE")`, but
there's only a single accel domain and it is a bit special, so it makes
sense to have a dedicated helper function for getting it.

Signed-off-by: Konrad Sztyber <konrad.sztyber@intel.com>
Change-Id: I07db7445ed9b109e66ecdbc0483a6a158a551070
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16376
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

include/spdk_internal/accel_module.h

@@ -210,4 +210,11 @@ static void __attribute__((constructor)) _spdk_accel_driver_register_##name(void
 	spdk_accel_driver_register(driver); \
 }
 
+/**
+ * Retrieves accel memory domain.
+ *
+ * \return Accel memory domain.
+ */
+struct spdk_memory_domain *spdk_accel_get_memory_domain(void);
+
 #endif

lib/accel/accel.c

@@ -1678,6 +1678,12 @@ spdk_accel_sequence_abort(struct spdk_accel_sequence *seq)
 	accel_sequence_put(seq);
 }
 
+struct spdk_memory_domain *
+spdk_accel_get_memory_domain(void)
+{
+	return g_accel_domain;
+}
+
 static struct spdk_accel_module_if *
 _module_find_by_name(const char *name)
 {

lib/accel/spdk_accel.map

@@ -41,6 +41,7 @@
 	spdk_accel_task_complete;
 	spdk_accel_sequence_continue;
 	spdk_accel_driver_register;
+	spdk_accel_get_memory_domain;
 
 	local: *;
 };