add CONFIG_SPI_IDLE_VAL for cf_spi.c to allow use of spi_mmc

This patch adds CONFIG_SPI_IDLE_VAL to cf_spi.c
The default setting is 0x0 to behave same as current version, in case
CONFIG_SPI_MMC is set, the value is set to 0xFFFF (all ones). In either
case, the value can be overwritten by board configuration.

Signed-off-by: Wolfgang Wegner <w.wegner@astro-kom.de>
Signed-off-by: Andy Fleming <afleming@freescale.com>

drivers/spi/cf_spi.c

@@ -49,6 +49,14 @@ extern void cfspi_release_bus(uint bus, uint cs);
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#ifndef CONFIG_SPI_IDLE_VAL
+#if defined(CONFIG_SPI_MMC)
+#define CONFIG_SPI_IDLE_VAL	0xFFFF
+#else
+#define CONFIG_SPI_IDLE_VAL	0x0
+#endif
+#endif
+
 #if defined(CONFIG_CF_DSPI)
 /* DSPI specific mode */
 #define SPI_MODE_MOD	0x00200000
@@ -145,7 +153,7 @@ int cfspi_xfer(struct spi_slave *slave, uint bitlen, const void *dout,
 			}
 
 			if (din != NULL) {
-				cfspi_tx(ctrl, 0);
+				cfspi_tx(ctrl, CONFIG_SPI_IDLE_VAL);
 				if (cfslave->charbit == 16)
 					*spi_rd16++ = cfspi_rx();
 				else
@@ -169,7 +177,7 @@ int cfspi_xfer(struct spi_slave *slave, uint bitlen, const void *dout,
 		}
 
 		if (din != NULL) {
-			cfspi_tx(ctrl, 0);
+			cfspi_tx(ctrl, CONFIG_SPI_IDLE_VAL);
 			if (cfslave->charbit == 16)
 				*spi_rd16 = cfspi_rx();
 			else
@@ -177,7 +185,7 @@ int cfspi_xfer(struct spi_slave *slave, uint bitlen, const void *dout,
 		}
 	} else {
 		/* dummy read */
-		cfspi_tx(ctrl, 0);
+		cfspi_tx(ctrl, CONFIG_SPI_IDLE_VAL);
 		cfspi_rx();
 	}