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ARC: [Review] Multi-platform image #6: cpu-to-dma-addr optional
All the current platforms can work with 0x8000_0000 based dma_addr_t since the Bus Bridges typically ignore the top bit (the only excpetion was Angel4 PCI-AHB bridge which we no longer care for). That way we don't need plat-specific cpu-addr to bus-addr conversion. Hooks still provided - just in case a platform has an obscure device which say needs 0 based bus address. That way <asm/dma_mapping.h> no longer needs to unconditinally include <plat/dma_addr.h> Also verfied that on Angel4 board, other peripherals (IDE-disk / EMAC) work fine with 0x8000_0000 based dma addresses. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Acked-by: Arnd Bergmann <arnd@arndb.de>
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3 changed files with 20 additions and 45 deletions
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@ -119,6 +119,10 @@ config CPU_BIG_ENDIAN
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help
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Build kernel for Big Endian Mode of ARC CPU
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# If a platform can't work with 0x8000_0000 based dma_addr_t
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config ARC_PLAT_NEEDS_CPU_TO_DMA
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bool
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config SMP
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bool "Symmetric Multi-Processing (Incomplete)"
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default n
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@ -13,7 +13,23 @@
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#include <asm-generic/dma-coherent.h>
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#include <asm/cacheflush.h>
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#ifndef CONFIG_ARC_PLAT_NEEDS_CPU_TO_DMA
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/*
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* dma_map_* API take cpu addresses, which is kernel logical address in the
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* untranslated address space (0x8000_0000) based. The dma address (bus addr)
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* ideally needs to be 0x0000_0000 based hence these glue routines.
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* However given that intermediate bus bridges can ignore the high bit, we can
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* do with these routines being no-ops.
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* If a platform/device comes up which sriclty requires 0 based bus addr
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* (e.g. AHB-PCI bridge on Angel4 board), then it can provide it's own versions
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*/
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#define plat_dma_addr_to_kernel(dev, addr) ((unsigned long)(addr))
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#define plat_kernel_addr_to_dma(dev, ptr) ((dma_addr_t)(ptr))
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#else
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#include <plat/dma_addr.h>
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#endif
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void *dma_alloc_noncoherent(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp);
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@ -1,45 +0,0 @@
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* vineetg: Feb 2009
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* -For AA4 board, kernel to DMA address APIs
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*/
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/*
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* kernel addresses are 0x800_000 based, while Bus addr are 0 based
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*/
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#ifndef __PLAT_DMA_ADDR_H
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#define __PLAT_DMA_ADDR_H
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#include <linux/device.h>
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static inline unsigned long plat_dma_addr_to_kernel(struct device *dev,
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dma_addr_t dma_addr)
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{
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return dma_addr + PAGE_OFFSET;
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}
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static inline dma_addr_t plat_kernel_addr_to_dma(struct device *dev, void *ptr)
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{
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unsigned long addr = (unsigned long)ptr;
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/*
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* To Catch buggy drivers which can call DMA map API with kernel vaddr
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* i.e. for buffers alloc via vmalloc or ioremap which are not
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* gaurnateed to be PHY contiguous and hence unfit for DMA anyways.
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* On ARC kernel virtual address is 0x7000_0000 to 0x7FFF_FFFF, so
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* ideally we want to check this range here, but our implementation is
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* better as it checks for even worse user virtual address as well.
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*/
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if (likely(addr >= PAGE_OFFSET))
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return addr - PAGE_OFFSET;
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BUG();
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return addr;
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}
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#endif
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