riscv: Add asm/dma-mapping.h for DMA mappings

This patch adds asm/dma-mapping.h for Linux-like DMA mappings
APIs required by some of the drivers (such as, Cadance MACB
Ethernet driver).

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>

diff --git a/arch/riscv/include/asm/dma-mapping.h b/arch/riscv/include/asm/dma-mapping.h
new file mode 100644 (file)
index 0000000..3d930c9
--- /dev/null
+++ b/arch/riscv/include/asm/dma-mapping.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2018 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __ASM_RISCV_DMA_MAPPING_H
+#define __ASM_RISCV_DMA_MAPPING_H
+
+#include <linux/dma-direction.h>
+
+#define dma_mapping_error(x, y)        0
+
+static inline void *dma_alloc_coherent(size_t len, unsigned long *handle)
+{
+       *handle = (unsigned long)memalign(ARCH_DMA_MINALIGN, len);
+       return (void *)*handle;
+}
+
+static inline void dma_free_coherent(void *addr)
+{
+       free(addr);
+}
+
+static inline unsigned long dma_map_single(volatile void *vaddr, size_t len,
+                                          enum dma_data_direction dir)
+{
+       return (unsigned long)vaddr;
+}
+
+static inline void dma_unmap_single(volatile void *vaddr, size_t len,
+                                   unsigned long paddr)
+{
+}
+
+#endif /* __ASM_RISCV_DMA_MAPPING_H */