Commit fc7943d2 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

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: default avatarVineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
parent decae9d3

arch/arc/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -119,6 +119,10 @@ config CPU_BIG_ENDIAN 
	help

	  Build kernel for Big Endian Mode of ARC CPU



# If a platform can't work with 0x8000_0000 based dma_addr_t

config ARC_PLAT_NEEDS_CPU_TO_DMA

	bool



config SMP

	bool "Symmetric Multi-Processing (Incomplete)"

	default n

arch/arc/include/asm/dma-mapping.h

+16 −0
Original line number Diff line number Diff line
@@ -13,7 +13,23 @@ 


#include <asm-generic/dma-coherent.h>

#include <asm/cacheflush.h>



#ifndef CONFIG_ARC_PLAT_NEEDS_CPU_TO_DMA

/*

 * dma_map_* API take cpu addresses, which is kernel logical address in the

 * untranslated address space (0x8000_0000) based. The dma address (bus addr)

 * ideally needs to be 0x0000_0000 based hence these glue routines.

 * However given that intermediate bus bridges can ignore the high bit, we can

 * do with these routines being no-ops.

 * If a platform/device comes up which sriclty requires 0 based bus addr

 * (e.g. AHB-PCI bridge on Angel4 board), then it can provide it's own versions

 */

#define plat_dma_addr_to_kernel(dev, addr) ((unsigned long)(addr))

#define plat_kernel_addr_to_dma(dev, ptr) ((dma_addr_t)(ptr))



#else

#include <plat/dma_addr.h>

#endif



void *dma_alloc_noncoherent(struct device *dev, size_t size,

			    dma_addr_t *dma_handle, gfp_t gfp);

arch/arc/plat-arcfpga/include/plat/dma_addr.h

deleted100644 → 0
+0 −45
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * vineetg: Feb 2009

 *  -For AA4 board, kernel to DMA address APIs

 */



/*

 * kernel addresses are 0x800_000 based, while Bus addr are 0 based

 */



#ifndef __PLAT_DMA_ADDR_H

#define __PLAT_DMA_ADDR_H



#include <linux/device.h>



static inline unsigned long plat_dma_addr_to_kernel(struct device *dev,

						    dma_addr_t dma_addr)

{

	return dma_addr + PAGE_OFFSET;

}



static inline dma_addr_t plat_kernel_addr_to_dma(struct device *dev, void *ptr)

{

	unsigned long addr = (unsigned long)ptr;

	/*

	 * To Catch buggy drivers which can call DMA map API with kernel vaddr

	 * i.e. for buffers alloc via vmalloc or ioremap which are not

	 * gaurnateed to be PHY contiguous and hence unfit for DMA anyways.

	 * On ARC kernel virtual address is 0x7000_0000 to 0x7FFF_FFFF, so

	 * ideally we want to check this range here, but our implementation is

	 * better as it checks for even worse user virtual address as well.

	 */

	if (likely(addr >= PAGE_OFFSET))

		return addr - PAGE_OFFSET;



	BUG();

	return addr;

}



#endif

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