From mboxrd@z Thu Jan  1 00:00:00 1970
From: Santosh Shilimkar <santosh.shilimkar@ti.com>
Subject: [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address
 translation
Date: Thu, 24 Apr 2014 11:30:05 -0400
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Cc: devicetree@vger.kernel.org, Grygorii Strashko <grygorii.strashko@ti.com>, Russell King <linux@arm.linux.org.uk>, Arnd Bergmann <arnd@arndb.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Linus Walleij <linus.walleij@linaro.org>, Grant Likely <grant.likely@linaro.org>, Rob Herring <robh+dt@kernel.org>, Santosh Shilimkar <santosh.shilimkar@ti.com>, Catalin Marinas <catalin.marinas@arm.com>, Olof Johansson <olof@lixom.net>, linux-arm-kernel@lists.infradead.org
List-Id: devicetree@vger.kernel.org

From: Grygorii Strashko <grygorii.strashko@ti.com>

In most of cases DMA addresses can be performed using offset value of
 Bus address space relatively to physical address space as following:

PFN->DMA:
 __pfn_to_phys(pfn + [-]dma_pfn_offset)

DMA->PFN:
 __phys_to_pfn(dma_addr) + [-]dma_pfn_offset

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
---
 arch/arm/include/asm/dma-mapping.h |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index e701a4d..424fda9 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -58,22 +58,35 @@ static inline int dma_set_mask(struct device *dev, u64 mask)
 #ifndef __arch_pfn_to_dma
 static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
 {
-	return (dma_addr_t)__pfn_to_bus(pfn);
+	if (!dev)
+		return (dma_addr_t)__pfn_to_bus(pfn);
+	else
+		return (dma_addr_t)__pfn_to_bus(pfn - dev->dma_pfn_offset);
 }
 
 static inline unsigned long dma_to_pfn(struct device *dev, dma_addr_t addr)
 {
-	return __bus_to_pfn(addr);
+	if (!dev)
+		return __bus_to_pfn(addr);
+	else
+		return __bus_to_pfn(addr) + dev->dma_pfn_offset;
 }
 
 static inline void *dma_to_virt(struct device *dev, dma_addr_t addr)
 {
-	return (void *)__bus_to_virt((unsigned long)addr);
+	if (!dev)
+		return (void *)__bus_to_virt((unsigned long)addr);
+	else
+		return (void *)__bus_to_virt(__pfn_to_bus(dma_to_pfn(dev, addr)));
 }
 
 static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
 {
-	return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
+	if (!dev)
+		return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
+	else
+		return pfn_to_dma(dev,
+				__bus_to_pfn(__virt_to_bus((unsigned long)(addr))));
 }
 
 #else
-- 
1.7.9.5