[PATCH v2 1/2] dw_dmac: make driver endianness configurable

[PATCH v2 1/2] dw_dmac: make driver endianness configurable

[Hein Tibosch]

The dw_dmac was originally developed for avr32 to be used with the
Synopsys DesignWare AHB DMA controller. After 2.6.38, device access was done
with the little-endian readl/writel functions. This didn't work on the
avr32 platform, because it needs native-endian (i.e. big-endian) accessors.
This patch makes the endianness configurable using 'DW_DMAC_BIG_ENDIAN_IO',
which will default be true for AVR32


Signed-off-by: Hein Tibosch <hein_tibosch@yahoo.es>
---
 drivers/dma/Kconfig        |   11 +++++++++++
 drivers/dma/dw_dmac_regs.h |   14 ++++++++++++++
 2 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index aadeb5b..a9f6781 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -89,6 +89,17 @@ 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
diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h
index f298f69..9758651 100644
--- a/drivers/dma/dw_dmac_regs.h
+++ b/drivers/dma/dw_dmac_regs.h
@@ -175,10 +175,17 @@ __dwc_regs(struct dw_dma_chan *dwc)
 	return dwc->ch_regs;
 }
 
+#ifdef CONFIG_DW_DMAC_BIG_ENDIAN_IO
+#define channel_readl(dwc, name) \
+	ioread32be(&(__dwc_regs(dwc)->name))
+#define channel_writel(dwc, name, val) \
+	iowrite32be((val), &(__dwc_regs(dwc)->name))
+#else
 #define channel_readl(dwc, name) \
 	readl(&(__dwc_regs(dwc)->name))
 #define channel_writel(dwc, name, val) \
 	writel((val), &(__dwc_regs(dwc)->name))
+#endif
 
 static inline struct dw_dma_chan *to_dw_dma_chan(struct dma_chan *chan)
 {
@@ -201,10 +208,17 @@ static inline struct dw_dma_regs __iomem *__dw_regs(struct dw_dma *dw)
 	return dw->regs;
 }
 
+#ifdef CONFIG_DW_DMAC_BIG_ENDIAN_IO
+#define dma_readl(dwc, name) \
+	ioread32be(&(__dw_regs(dw)->name))
+#define dma_writel(dwc, name, val) \
+	iowrite32be((val), &(__dw_regs(dw)->name))
+#else
 #define dma_readl(dw, name) \
 	readl(&(__dw_regs(dw)->name))
 #define dma_writel(dw, name, val) \
 	writel((val), &(__dw_regs(dw)->name))
+#endif
 
 #define channel_set_bit(dw, reg, mask) \
 	dma_writel(dw, reg, ((mask) << 8) | (mask))
-- 
1.7.8.0

Re: [PATCH v2 1/2] dw_dmac: make driver endianness configurable

[Arnd Bergmann]

On Thursday 30 August 2012, Hein Tibosch wrote:
> The dw_dmac was originally developed for avr32 to be used with the
> Synopsys DesignWare AHB DMA controller. After 2.6.38, device access was done
> with the little-endian readl/writel functions. This didn't work on the
> avr32 platform, because it needs native-endian (i.e. big-endian) accessors.
> This patch makes the endianness configurable using 'DW_DMAC_BIG_ENDIAN_IO',
> which will default be true for AVR32
> 
> 
> Signed-off-by: Hein Tibosch <hein_tibosch@yahoo.es>

Acked-by: Arnd Bergmann <arnd.bergmann@linaro.org>