From: Santosh Shilimkar <santosh.shilimkar@ti.com>
Date: Thu, 24 Apr 2014 15:30:01 +0000 (-0400)
Subject: device: introduce per device dma_pfn_offset
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~52^2~4^2^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8febcaa2aac184d7e729acb75e9c4b80b04ad1b9;p=pandora-kernel.git

device: introduce per device dma_pfn_offset

On few architectures, there are few restrictions on DMAble area of system
RAM. That also means that devices needs to know about this restrictions so
that the dma_masks can be updated accordingly and dma address translation
helpers can add/subtract the dma offset.

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

So we introduce per device dma_pfn_offset which can be popullated
by architecture init code while creating the devices.

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: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
---

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