This patch includes the basic infrastructure to use swiotlb
bounce buffering on 32-bit powerpc.  It is not yet enabled on
any platforms.  Probably the most interesting bit is the
addition of addr_needs_map to dma_ops - we need this as
a dma_op because the decision of whether or not an addr
can be mapped by a device is device-specific.

Signed-off-by: Becky Bruce <redacted>
---
 arch/powerpc/Kconfig                   |   12 ++-
 arch/powerpc/include/asm/dma-mapping.h |   11 ++
 arch/powerpc/include/asm/swiotlb.h     |   27 +++++
 arch/powerpc/kernel/Makefile           |    1 +
 arch/powerpc/kernel/dma-swiotlb.c      |  163 ++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/dma.c              |    2 +-
 arch/powerpc/kernel/setup_32.c         |    6 +
 arch/powerpc/kernel/setup_64.c         |    6 +
 8 files changed, 226 insertions(+), 2 deletions(-)
 create mode 100644 arch/powerpc/include/asm/swiotlb.h
 create mode 100644 arch/powerpc/kernel/dma-swiotlb.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a0d1146..54e519a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -296,9 +296,19 @@ config IOMMU_VMERGE
 config IOMMU_HELPER
 	def_bool PPC64
 
+config SWIOTLB
+	bool "SWIOTLB support"
+	default n
+	select IOMMU_HELPER
+	---help---
+	  Support for IO bounce buffering for systems without an IOMMU.
+	  This allows us to DMA to the full physical address space on
+	  platforms where the size of a physical address is larger
+	  than the bus address.  Not all platforms support this.
+
 config PPC_NEED_DMA_SYNC_OPS
 	def_bool y
-	depends on NOT_COHERENT_CACHE
+	depends on (NOT_COHERENT_CACHE || SWIOTLB)
 
 config HOTPLUG_CPU
 	bool "Support for enabling/disabling CPUs"

diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index c69f2b5..71bbc17 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h

@@ -15,9 +15,18 @@
 #include <linux/scatterlist.h>
 #include <linux/dma-attrs.h>
 #include <asm/io.h>
+#include <asm/swiotlb.h>
 
 #define DMA_ERROR_CODE		(~(dma_addr_t)0x0)
 
+/* Some dma direct funcs must be visible for use in other dma_ops */
+extern void *dma_direct_alloc_coherent(struct device *dev, size_t size,
+				       dma_addr_t *dma_handle, gfp_t flag);
+extern void dma_direct_free_coherent(struct device *dev, size_t size,
+				     void *vaddr, dma_addr_t dma_handle);
+
+extern unsigned long get_dma_direct_offset(struct device *dev);
+
 #ifdef CONFIG_NOT_COHERENT_CACHE
 /*
  * DMA-consistent mapping functions for PowerPCs that don't support

@@ -76,6 +85,8 @@ struct dma_mapping_ops {
 				dma_addr_t dma_address, size_t size,
 				enum dma_data_direction direction,
 				struct dma_attrs *attrs);
+	int		(*addr_needs_map)(struct device *dev, dma_addr_t addr,
+				size_t size);
 #ifdef CONFIG_PPC_NEED_DMA_SYNC_OPS
 	void            (*sync_single_range_for_cpu)(struct device *hwdev,
 				dma_addr_t dma_handle, unsigned long offset,

diff --git a/arch/powerpc/include/asm/swiotlb.h b/arch/powerpc/include/asm/swiotlb.h
new file mode 100644
index 0000000..30891d6
--- /dev/null
+++ b/arch/powerpc/include/asm/swiotlb.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2009 Becky Bruce, Freescale Semiconductor
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ */
+
+#ifndef __ASM_SWIOTLB_H
+#define __ASM_SWIOTLB_H
+
+#include <linux/swiotlb.h>
+
+extern struct dma_mapping_ops swiotlb_dma_ops;
+extern struct dma_mapping_ops swiotlb_pci_dma_ops;
+
+int swiotlb_arch_address_needs_mapping(struct device *, dma_addr_t,
+				       size_t size);
+
+static inline void dma_mark_clean(void *addr, size_t size) {}
+
+extern unsigned int ppc_swiotlb_enable;
+int __init swiotlb_setup_bus_notifier(void);
+
+#endif /* __ASM_SWIOTLB_H */

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 71901fb..34c0a95 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile

@@ -82,6 +82,7 @@ obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_PPC_UDBG_16550)	+= legacy_serial.o udbg_16550.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
+obj-$(CONFIG_SWIOTLB)		+= dma-swiotlb.o
 
 pci64-$(CONFIG_PPC64)		+= pci_dn.o isa-bridge.o
 obj-$(CONFIG_PCI)		+= pci_$(CONFIG_WORD_SIZE).o $(pci64-y) \

diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma-swiotlb.c
new file mode 100644
index 0000000..68ccf11
--- /dev/null
+++ b/arch/powerpc/kernel/dma-swiotlb.c

@@ -0,0 +1,163 @@
+/*
+ * Contains routines needed to support swiotlb for ppc.
+ *
+ * Copyright (C) 2009 Becky Bruce, Freescale Semiconductor
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/pfn.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pci.h>
+
+#include <asm/machdep.h>
+#include <asm/swiotlb.h>
+#include <asm/dma.h>
+#include <asm/abs_addr.h>
+
+int swiotlb __read_mostly;
+unsigned int ppc_swiotlb_enable;
+
+void *swiotlb_bus_to_virt(struct device *hwdev, dma_addr_t addr)
+{
+	unsigned long pfn = PFN_DOWN(swiotlb_bus_to_phys(hwdev, addr));
+	void *pageaddr = page_address(pfn_to_page(pfn));
+
+	if (pageaddr != NULL)
+		return pageaddr + (addr % PAGE_SIZE);
+	return NULL;
+}
+
+dma_addr_t swiotlb_phys_to_bus(struct device *hwdev, phys_addr_t paddr)
+{
+	return paddr + get_dma_direct_offset(hwdev);
+}
+
+phys_addr_t swiotlb_bus_to_phys(struct device *hwdev, dma_addr_t baddr)
+
+{
+	return baddr - get_dma_direct_offset(hwdev);
+}
+
+/*
+ * Determine if an address needs bounce buffering via swiotlb.
+ * Going forward I expect the swiotlb code to generalize on using
+ * a dma_ops->addr_needs_map, and this function will move from here to the
+ * generic swiotlb code.
+ */
+int
+swiotlb_arch_address_needs_mapping(struct device *hwdev, dma_addr_t addr,
+				   size_t size)
+{
+	struct dma_mapping_ops *dma_ops = get_dma_ops(hwdev);
+
+	BUG_ON(!dma_ops);
+	return dma_ops->addr_needs_map(hwdev, addr, size);
+}
+
+/*
+ * Determine if an address is reachable by a pci device, or if we must bounce.
+ */
+static int
+swiotlb_pci_addr_needs_map(struct device *hwdev, dma_addr_t addr, size_t size)
+{
+	u64 mask = dma_get_mask(hwdev);
+	dma_addr_t max;
+	struct pci_controller *hose;
+	struct pci_dev *pdev = to_pci_dev(hwdev);
+
+	hose = pci_bus_to_host(pdev->bus);
+	max = hose->dma_window_base_cur + hose->dma_window_size;
+
+	/* check that we're within mapped pci window space */
+	if ((addr + size > max) | (addr < hose->dma_window_base_cur))
+		return 1;
+
+	return !is_buffer_dma_capable(mask, addr, size);
+}
+
+static int
+swiotlb_addr_needs_map(struct device *hwdev, dma_addr_t addr, size_t size)
+{
+	return !is_buffer_dma_capable(dma_get_mask(hwdev), addr, size);
+}