MIPS: Loongson64: Enable DMA noncoherent support

There are some Loongson64 systems come with broken coherent DMA
support, firmware will set a bit in boot_param and pass nocoherentio
in cmdline.

However nonconherent support was missed out when spin off Loongson-2EF
form Loongson64, and that boot_param change never made itself into
upstream.

Support DMA noncoherent properly to get those systems working.

Cc: [e-mail]
Fixes: 71e2f4dd5a65 ("MIPS: Fork loongson2ef from loongson64")
Signed-off-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/Kconfig

···
 
 config MACH_LOONGSON64
 	bool "Loongson 64-bit family of machines"
+	select ARCH_DMA_DEFAULT_COHERENT
 	select ARCH_SPARSEMEM_ENABLE
 	select ARCH_MIGHT_HAVE_PC_PARPORT
 	select ARCH_MIGHT_HAVE_PC_SERIO
···
 	select CPU_SUPPORTS_MSA
 	select CPU_DIEI_BROKEN if !LOONGSON3_ENHANCEMENT
 	select CPU_MIPSR2_IRQ_VI
+	select DMA_NONCOHERENT
 	select WEAK_ORDERING
 	select WEAK_REORDERING_BEYOND_LLSC
 	select MIPS_ASID_BITS_VARIABLE

arch/mips/include/asm/mach-loongson64/boot_param.h

···
 	u64 pci_io_start_addr;
 	u64 pci_io_end_addr;
 	u64 pci_config_addr;
-	u32 dma_mask_bits;
+	u16 dma_mask_bits;
+	u16 dma_noncoherent;
 } __packed;
 
 struct interface_info {

arch/mips/loongson64/env.c

···
  * Copyright (C) 2009 Lemote Inc.
  * Author: Wu Zhangjin, [e-mail]
  */
+
+#include <linux/dma-map-ops.h>
 #include <linux/export.h>
 #include <linux/pci_ids.h>
 #include <asm/bootinfo.h>
···
 
 	loongson_sysconf.dma_mask_bits = eirq_source->dma_mask_bits;
 	if (loongson_sysconf.dma_mask_bits < 32 ||
-		loongson_sysconf.dma_mask_bits > 64)
+			loongson_sysconf.dma_mask_bits > 64) {
 		loongson_sysconf.dma_mask_bits = 32;
+		dma_default_coherent = true;
+	} else {
+		dma_default_coherent = !eirq_source->dma_noncoherent;
+	}
+
+	pr_info("Firmware: Coherent DMA: %s\n", dma_default_coherent ? "on" : "off");
 
 	loongson_sysconf.restart_addr = boot_p->reset_system.ResetWarm;
 	loongson_sysconf.poweroff_addr = boot_p->reset_system.Shutdown;