MIPS: loongson64: use generic dma noncoherent ops

Provide phys_to_dma/dma_to_phys helpers, everything else is generic.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Patchwork: https://patchwork.linux-mips.org/patch/19545/
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Tom Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-mips@linux-mips.org

arch/mips/loongson64/Kconfig

@@ -13,7 +13,6 @@ config LEMOTE_FULOONG2E
 	select CSRC_R4K
 	select SYS_HAS_CPU_LOONGSON2E
 	select DMA_NONCOHERENT
-	select MIPS_DMA_DEFAULT
 	select BOOT_ELF32
 	select BOARD_SCACHE
 	select HW_HAS_PCI
@@ -45,7 +44,6 @@ config LEMOTE_MACH2F
 	select CS5536
 	select CSRC_R4K if ! MIPS_EXTERNAL_TIMER
 	select DMA_NONCOHERENT
-	select MIPS_DMA_DEFAULT
 	select GENERIC_ISA_DMA_SUPPORT_BROKEN
 	select HAVE_CLK
 	select HW_HAS_PCI

arch/mips/loongson64/common/Makefile

@@ -6,6 +6,7 @@
 obj-y += setup.o init.o cmdline.o env.o time.o reset.o irq.o \
     bonito-irq.o mem.o machtype.o platform.o serial.o
 obj-$(CONFIG_PCI) += pci.o
+obj-$(CONFIG_CPU_LOONGSON2) += dma.o
 
 #
 # Serial port support

arch/mips/loongson64/common/dma.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/dma-direct.h>
+
+dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+	return paddr | 0x80000000;
+}
+
+phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dma_addr)
+{
+#if defined(CONFIG_CPU_LOONGSON2F) && defined(CONFIG_64BIT)
+	if (dma_addr > 0x8fffffff)
+		return dma_addr;
+	return dma_addr & 0x0fffffff;
+#else
+	return dma_addr & 0x7fffffff;
+#endif
+}