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From: Albert Herranz on 7 Mar 2010 07:20
The current SWIOTLB code does not support NOT_COHERENT_CACHE platforms.
This patch adds support for NOT_COHERENT_CACHE platforms to SWIOTLB by
adding two platform specific functions swiotlb_dma_sync_page() and
swiotlb_dma_sync() which can be used to explicitly manage cache coherency.

On PowerPC these functions are mapped to their corresponding
__dma_sync_page() and __dma_sync() functions.
On other architectures using SWIOTLB these functions are optimized out.

This will be used later to support SWIOTLB on the Nintendo Wii video game
console.

Signed-off-by: Albert Herranz <albert_herranz(a)yahoo.es>
CC: linuxppc-dev(a)lists.ozlabs.org
CC: linux-kernel(a)vger.kernel.org
CC: x86(a)kernel.org
CC: linux-ia64(a)vger.kernel.org
---
arch/ia64/include/asm/swiotlb.h | 10 ++++++++++
arch/powerpc/include/asm/swiotlb.h | 3 +++
arch/x86/include/asm/swiotlb.h | 10 ++++++++++
lib/swiotlb.c | 30 ++++++++++++++++++++++++------
4 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/arch/ia64/include/asm/swiotlb.h b/arch/ia64/include/asm/swiotlb.h
index f0acde6..6722090 100644
--- a/arch/ia64/include/asm/swiotlb.h
+++ b/arch/ia64/include/asm/swiotlb.h
@@ -14,4 +14,14 @@ static inline void pci_swiotlb_init(void)
}
#endif

+static inline void swiotlb_dma_sync_page(struct page *page,
+ unsigned long offset,
+ size_t size, int direction)
+{
+}
+
+static inline void swiotlb_dma_sync(void *vaddr, size_t size, int direction)
+{
+}
+
#endif /* ASM_IA64__SWIOTLB_H */
diff --git a/arch/powerpc/include/asm/swiotlb.h b/arch/powerpc/include/asm/swiotlb.h
index 8979d4c..603b343 100644
--- a/arch/powerpc/include/asm/swiotlb.h
+++ b/arch/powerpc/include/asm/swiotlb.h
@@ -22,4 +22,7 @@ int __init swiotlb_setup_bus_notifier(void);

extern void pci_dma_dev_setup_swiotlb(struct pci_dev *pdev);

+#define swiotlb_dma_sync_page __dma_sync_page
+#define swiotlb_dma_sync __dma_sync
+
#endif /* __ASM_SWIOTLB_H */
diff --git a/arch/x86/include/asm/swiotlb.h b/arch/x86/include/asm/swiotlb.h
index 8085277..e5f6d9c 100644
--- a/arch/x86/include/asm/swiotlb.h
+++ b/arch/x86/include/asm/swiotlb.h
@@ -20,4 +20,14 @@ static inline void pci_swiotlb_init(void)

static inline void dma_mark_clean(void *addr, size_t size) {}

+static inline void swiotlb_dma_sync_page(struct page *page,
+ unsigned long offset,
+ size_t size, int direction)
+{
+}
+
+static inline void swiotlb_dma_sync(void *vaddr, size_t size, int direction)
+{
+}
+
#endif /* _ASM_X86_SWIOTLB_H */
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 94db5df..8f2dad9 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -346,10 +346,13 @@ static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
local_irq_save(flags);
buffer = kmap_atomic(pfn_to_page(pfn),
KM_BOUNCE_READ);
- if (dir == DMA_TO_DEVICE)
+ if (dir == DMA_TO_DEVICE) {
memcpy(dma_addr, buffer + offset, sz);
- else
+ swiotlb_dma_sync(dma_addr, sz, dir);
+ } else {
+ swiotlb_dma_sync(dma_addr, sz, dir);
memcpy(buffer + offset, dma_addr, sz);
+ }
kunmap_atomic(buffer, KM_BOUNCE_READ);
local_irq_restore(flags);

@@ -359,10 +362,14 @@ static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
offset = 0;
}
} else {
- if (dir == DMA_TO_DEVICE)
+ if (dir == DMA_TO_DEVICE) {
memcpy(dma_addr, phys_to_virt(phys), size);
- else
+ swiotlb_dma_sync(dma_addr, size, dir);
+
+ } else {
+ swiotlb_dma_sync(dma_addr, size, dir);
memcpy(phys_to_virt(phys), dma_addr, size);
+ }
}
}

@@ -542,6 +549,8 @@ sync_single(struct device *hwdev, char *dma_addr, size_t size,
}
}

+#ifndef CONFIG_NOT_COHERENT_CACHE
+
void *
swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, gfp_t flags)
@@ -606,6 +615,8 @@ swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
}
EXPORT_SYMBOL(swiotlb_free_coherent);

+#endif /* !CONFIG_NOT_COHERENT_CACHE */
+
static void
swiotlb_full(struct device *dev, size_t size, int dir, int do_panic)
{
@@ -652,8 +663,10 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
* we can safely return the device addr and not worry about bounce
* buffering it.
*/
- if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
+ if (dma_capable(dev, dev_addr, size) && !swiotlb_force) {
+ swiotlb_dma_sync_page(page, offset, size, dir);
return dev_addr;
+ }

/*
* Oh well, have to allocate and map a bounce buffer.
@@ -739,6 +752,8 @@ swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
return;
}

+ swiotlb_dma_sync(phys_to_virt(paddr), size, dir);
+
if (dir != DMA_FROM_DEVICE)
return;

@@ -835,8 +850,11 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
return 0;
}
sg->dma_address = swiotlb_virt_to_bus(hwdev, map);
- } else
+ } else {
+ swiotlb_dma_sync_page(sg_page(sg), sg->offset,
+ sg->length, dir);
sg->dma_address = dev_addr;
+ }
sg->dma_length = sg->length;
}
return nelems;
--
1.6.3.3

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Prev: [RFC PATCH v3 05/11] swiotlb: add swiotlb_set_default_size()
Next: [RFC] IIO event naming.