Commit d5ea7b5e authored by Hein Tibosch's avatar Hein Tibosch Committed by Linus Torvalds
Browse files

drivers/dma/dw_dmac: make driver's endianness configurable 

The dw_dmac driver was originally developed for avr32 to be used with the
Synopsys DesignWare AHB DMA controller.  Starting from 2.6.38, access to
the device's i/o memory was done with the little-endian readl/writel
functions(1)

This broke the driver for the avr32 platform, because it needs big
(native) endian accessors.  This patch makes the endianness configurable
using 'DW_DMAC_BIG_ENDIAN_IO', which will default be true for AVR32

I submitted this patch before(2) but then waited for Andy to finish other
changes to the same module(3).

(1) https://patchwork.kernel.org/patch/608211
(2) https://lkml.org/lkml/2012/8/26/148
(3) https://lkml.org/lkml/2012/9/21/173



Signed-off-by: default avatarHein Tibosch <hein_tibosch@yahoo.es>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: Havard Skinnemoen <havard@skinnemoen.net>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 35cfa2b0

drivers/dma/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -90,6 +90,17 @@ config DW_DMAC 
	  Support the Synopsys DesignWare AHB DMA controller.  This

	  can be integrated in chips such as the Atmel AT32ap7000.



config DW_DMAC_BIG_ENDIAN_IO

	bool "Use big endian I/O register access"

	default y if AVR32

	depends on DW_DMAC

	help

	  Say yes here to use big endian I/O access when reading and writing

	  to the DMA controller registers. This is needed on some platforms,

	  like the Atmel AVR32 architecture.



	  If unsure, use the default setting.



config AT_HDMAC

	tristate "Atmel AHB DMA support"

	depends on ARCH_AT91

drivers/dma/dw_dmac_regs.h

+13 −5
Original line number Diff line number Diff line
@@ -98,9 +98,17 @@ struct dw_dma_regs { 
	u32	DW_PARAMS;

};



#ifdef CONFIG_DW_DMAC_BIG_ENDIAN_IO

#define dma_readl_native ioread32be

#define dma_writel_native iowrite32be

#else

#define dma_readl_native readl

#define dma_writel_native writel

#endif



/* To access the registers in early stage of probe */

#define dma_read_byaddr(addr, name) \

	readl((addr) + offsetof(struct dw_dma_regs, name))

	dma_readl_native((addr) + offsetof(struct dw_dma_regs, name))



/* Bitfields in DW_PARAMS */

#define DW_PARAMS_NR_CHAN	8		/* number of channels */
@@ -216,9 +224,9 @@ __dwc_regs(struct dw_dma_chan *dwc) 
}



#define channel_readl(dwc, name) \

	readl(&(__dwc_regs(dwc)->name))

	dma_readl_native(&(__dwc_regs(dwc)->name))

#define channel_writel(dwc, name, val) \

	writel((val), &(__dwc_regs(dwc)->name))

	dma_writel_native((val), &(__dwc_regs(dwc)->name))



static inline struct dw_dma_chan *to_dw_dma_chan(struct dma_chan *chan)

{
@@ -246,9 +254,9 @@ static inline struct dw_dma_regs __iomem *__dw_regs(struct dw_dma *dw) 
}



#define dma_readl(dw, name) \

	readl(&(__dw_regs(dw)->name))

	dma_readl_native(&(__dw_regs(dw)->name))

#define dma_writel(dw, name, val) \

	writel((val), &(__dw_regs(dw)->name))

	dma_writel_native((val), &(__dw_regs(dw)->name))



#define channel_set_bit(dw, reg, mask) \

	dma_writel(dw, reg, ((mask) << 8) | (mask))

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