MIPS: loongson: untangle dma implementations

Only loongson-3 is DMA coherent and uses swiotlb.  So move the dma
address translations stubs directly to the loongson-3 code, and remove
a few Kconfig indirections.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Patchwork: https://patchwork.linux-mips.org/patch/19539/
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/Kconfig

@@ -454,7 +454,6 @@ config MACH_LOONGSON32
 
 config MACH_LOONGSON64
 	bool "Loongson-2/3 family of machines"
-	select ARCH_HAS_PHYS_TO_DMA
 	select SYS_SUPPORTS_ZBOOT
 	help
 	  This enables the support of Loongson-2/3 family of machines.
@@ -1389,6 +1388,7 @@ choice
 config CPU_LOONGSON3
 	bool "Loongson 3 CPU"
 	depends on SYS_HAS_CPU_LOONGSON3
+	select ARCH_HAS_PHYS_TO_DMA
 	select CPU_SUPPORTS_64BIT_KERNEL
 	select CPU_SUPPORTS_HIGHMEM
 	select CPU_SUPPORTS_HUGEPAGES

arch/mips/loongson64/Kconfig

@@ -93,7 +93,6 @@ config LOONGSON_MACH3X
 	select LOONGSON_MC146818
 	select ZONE_DMA32
 	select LEFI_FIRMWARE_INTERFACE
-	select PHYS48_TO_HT40
 	help
 		Generic Loongson 3 family machines utilize the 3A/3B revision
 		of Loongson processor and RS780/SBX00 chipset.
@@ -132,10 +131,6 @@ config LOONGSON_UART_BASE
 	default y
 	depends on EARLY_PRINTK || SERIAL_8250
 
-config PHYS48_TO_HT40
-	bool
-	default y if CPU_LOONGSON3
-
 config LOONGSON_MC146818
 	bool
 	default n

arch/mips/loongson64/common/Makefile

@@ -25,8 +25,3 @@ obj-$(CONFIG_CS5536) += cs5536/
 #
 
 obj-$(CONFIG_SUSPEND) += pm.o
-
-#
-# Big Memory (SWIOTLB) Support
-#
-obj-$(CONFIG_SWIOTLB) += dma-swiotlb.o

arch/mips/loongson64/loongson-3/Makefile

@@ -1,7 +1,7 @@
 #
 # Makefile for Loongson-3 family machines
 #
-obj-y			+= irq.o cop2-ex.o platform.o acpi_init.o
+obj-y			+= irq.o cop2-ex.o platform.o acpi_init.o dma.o
 
 obj-$(CONFIG_SMP)	+= smp.o
 

arch/mips/loongson64/loongson-3/dma.c

@@ -5,26 +5,18 @@
 
 dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
-	long nid;
-#ifdef CONFIG_PHYS48_TO_HT40
 	/* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
 	 * Loongson-3's 48bit address space and embed it into 40bit */
-	nid = (paddr >> 44) & 0x3;
-	paddr = ((nid << 44) ^ paddr) | (nid << 37);
-#endif
-	return paddr;
+	long nid = (paddr >> 44) & 0x3;
+	return ((nid << 44) ^ paddr) | (nid << 37);
 }
 
 phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
 {
-	long nid;
-#ifdef CONFIG_PHYS48_TO_HT40
 	/* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
 	 * Loongson-3's 48bit address space and embed it into 40bit */
-	nid = (daddr >> 37) & 0x3;
-	daddr = ((nid << 37) ^ daddr) | (nid << 44);
-#endif
-	return daddr;
+	long nid = (daddr >> 37) & 0x3;
+	return ((nid << 37) ^ daddr) | (nid << 44);
 }
 
 void __init plat_swiotlb_setup(void)