From 8febcaa2aac184d7e729acb75e9c4b80b04ad1b9 Mon Sep 17 00:00:00 2001
From: Santosh Shilimkar <santosh.shilimkar@ti.com>
Date: Thu, 24 Apr 2014 11:30:01 -0400
Subject: [PATCH] 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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