Add a generic armv7 bus dma tag.

sys/arch/arm/arm32/armv7_generic_dma.c

@@ -0,0 +1,40 @@
+/* $NetBSD: armv7_generic_dma.c,v 1.1 2017/05/28 00:34:51 jmcneill Exp $ */
+
+/*-
+ * Copyright (c) 2017 Jared McNeill <jmcneill@invisible.ca>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__KERNEL_RCSID(0, "$NetBSD: armv7_generic_dma.c,v 1.1 2017/05/28 00:34:51 jmcneill Exp $");
+
+#define	_ARM32_BUS_DMA_PRIVATE
+#include <sys/param.h>
+#include <sys/bus.h>
+
+struct arm32_bus_dma_tag armv7_generic_dma_tag = {
+	_BUS_DMAMAP_FUNCS,
+	_BUS_DMAMEM_FUNCS,
+	_BUS_DMATAG_FUNCS,
+};