spi: atmel: add WDRBT bit to avoid receive overrun

The atmel at91sam9x5 series spi has feature to avoid receive overren

Using the patch to enable it

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>

drivers/spi/atmel_spi.c

@@ -92,6 +92,9 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 	as->slave.cs = cs;
 	as->regs = regs;
 	as->mr = ATMEL_SPI_MR_MSTR | ATMEL_SPI_MR_MODFDIS
+#if defined(CONFIG_AT91SAM9X5)
+			| ATMEL_SPI_MR_WDRBT
+#endif
 			| ATMEL_SPI_MR_PCS(~(1 << cs) & 0xf);
 	spi_writel(as, CSR(cs), csrx);
 

drivers/spi/atmel_spi.h

@@ -26,6 +26,7 @@
 #define ATMEL_SPI_MR_PCSDEC		(1 << 2)
 #define ATMEL_SPI_MR_FDIV		(1 << 3)
 #define ATMEL_SPI_MR_MODFDIS		(1 << 4)
+#define ATMEL_SPI_MR_WDRBT		(1 << 5)
 #define ATMEL_SPI_MR_LLB		(1 << 7)
 #define ATMEL_SPI_MR_PCS(x)		(((x) & 15) << 16)
 #define ATMEL_SPI_MR_DLYBCS(x)		((x) << 24)