linux-kernel - Re: [PATCH v3 5/7] ARM: dma: Use dma_pfn

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Date:	Fri, 2 May 2014 09:32:56 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Santosh Shilimkar <santosh.shilimkar@...com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address translation

On Thu, Apr 24, 2014 at 10:30 AM, Santosh Shilimkar
<santosh.shilimkar@...com> wrote:
> From: Grygorii Strashko <grygorii.strashko@...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@...uxfoundation.org>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Olof Johansson <olof@...om.net>
> Cc: Grant Likely <grant.likely@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>

Reviewed-by: Rob Herring <robh@...nel.org>

> ---
>  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
>
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