mx28evk: add SPI support

This patch adds SPI support for the MX28EVK. Support for
an optionally installed SPI flash is also added. An example
configuration for redundant envrionment from SPI flash is also
added but disabled by default.

This patch has been tested on a MX28EVK Rev. D with an installed
SST25VF032B 32Mbit SPI flash.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu>
Acked-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/board/freescale/mx28evk/iomux.c b/board/freescale/mx28evk/iomux.c
index 904e3f3..396761b 100644
--- a/board/freescale/mx28evk/iomux.c
+++ b/board/freescale/mx28evk/iomux.c
@@ -28,6 +28,7 @@
 #define	MUX_CONFIG_SSP0	(MXS_PAD_3V3 | MXS_PAD_8MA | MXS_PAD_PULLUP)
 #define	MUX_CONFIG_ENET	(MXS_PAD_3V3 | MXS_PAD_8MA | MXS_PAD_PULLUP)
 #define	MUX_CONFIG_EMI	(MXS_PAD_3V3 | MXS_PAD_12MA | MXS_PAD_NOPULL)
+#define	MUX_CONFIG_SSP2	(MXS_PAD_3V3 | MXS_PAD_4MA | MXS_PAD_PULLUP)
 
 const iomux_cfg_t iomux_setup[] = {
 	/* DUART */
@@ -130,6 +131,13 @@
 	MX28_PAD_EMI_CE0N__EMI_CE0N | MUX_CONFIG_EMI,
 	MX28_PAD_EMI_CE1N__EMI_CE1N | MUX_CONFIG_EMI,
 	MX28_PAD_EMI_CKE__EMI_CKE | MUX_CONFIG_EMI,
+
+	/* SPI2 (for SPI flash) */
+	MX28_PAD_SSP2_SCK__SSP2_SCK | MUX_CONFIG_SSP2,
+	MX28_PAD_SSP2_MOSI__SSP2_CMD | MUX_CONFIG_SSP2,
+	MX28_PAD_SSP2_MISO__SSP2_D0 | MUX_CONFIG_SSP2,
+	MX28_PAD_SSP2_SS0__SSP2_D3 |
+		(MXS_PAD_3V3 | MXS_PAD_8MA | MXS_PAD_PULLUP),
 };
 
 void board_init_ll(void)