set up dma_ops appropriately

This patch introduces a global pointer, dma_ops, which points to an
appropriate dma_mapping_ops that the kernel should use. This is a
common way to handle multiple dma_mapping_ops (X86, POWER, and SPARC).

dma_ops is set in platform_dma_init. We also set it by hand where
machvec_init is callev via subsys_initcall.

- IA64_DIG_VTD uses vtd_dma_ops.
- IA64_HP_ZX1 uses sba_dma_ops.
- IA64_HP_ZX1_SWIOTLB uses hwsw_dma_ops.
- IA64_SGI_SN2 uses sn_dma_ops.
- The rest use swiotlb_dma_ops.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/ia64/kernel/Makefile

@@ -7,7 +7,7 @@ extra-y	:= head.o init_task.o vmlinux.lds
 obj-y := acpi.o entry.o efi.o efi_stub.o gate-data.o fsys.o ia64_ksyms.o irq.o irq_ia64.o	\
 	 irq_lsapic.o ivt.o machvec.o pal.o patch.o process.o perfmon.o ptrace.o sal.o		\
 	 salinfo.o setup.o signal.o sys_ia64.o time.o traps.o unaligned.o \
-	 unwind.o mca.o mca_asm.o topology.o
+	 unwind.o mca.o mca_asm.o topology.o dma-mapping.o
 
 obj-$(CONFIG_IA64_BRL_EMU)	+= brl_emu.o
 obj-$(CONFIG_IA64_GENERIC)	+= acpi-ext.o

arch/ia64/kernel/dma-mapping.c

@@ -0,0 +1,4 @@
+#include <linux/dma-mapping.h>
+
+struct dma_mapping_ops *dma_ops;
+EXPORT_SYMBOL(dma_ops);

arch/ia64/kernel/pci-dma.c

@@ -41,8 +41,11 @@ struct device fallback_dev = {
 	.dma_mask = &fallback_dev.coherent_dma_mask,
 };
 
+extern struct dma_mapping_ops vtd_dma_ops;
+
 void __init pci_iommu_alloc(void)
 {
+	dma_ops = &vtd_dma_ops;
 	/*
 	 * The order of these functions is important for
 	 * fall-back/fail-over reasons
@@ -76,9 +79,6 @@ iommu_dma_init(void)
 	return;
 }
 
-struct dma_mapping_ops *dma_ops;
-EXPORT_SYMBOL(dma_ops);
-
 int iommu_dma_supported(struct device *dev, u64 mask)
 {
 	struct dma_mapping_ops *ops = get_dma_ops(dev);

arch/ia64/kernel/pci-swiotlb.c

@@ -37,6 +37,12 @@ struct dma_mapping_ops swiotlb_dma_ops = {
 	.mapping_error = swiotlb_dma_mapping_error,
 };
 
+void swiotlb_dma_init(void)
+{
+	dma_ops = &swiotlb_dma_ops;
+	swiotlb_init();
+}
+
 void __init pci_swiotlb_init(void)
 {
 	if (!iommu_detected) {