driver/ddr: Add 256 byte interleaving support

Freescale LayerScape SoCs support controller interleaving on 256 byte size.
This interleaving is mandoratory.

Signed-off-by: York Sun <yorksun@freescale.com>
diff --git a/README b/README
index 355e898..f51f17e 100644
--- a/README
+++ b/README
@@ -497,6 +497,11 @@
 		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
 		it could be different for ARM SoCs.
 
+		CONFIG_SYS_FSL_DDR_INTLV_256B
+		DDR controller interleaving on 256-byte. This is a special
+		interleaving mode, handled by Dickens for Freescale layerscape
+		SoCs with ARM core.
+
 - Intel Monahans options:
 		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
 
diff --git a/drivers/ddr/fsl/ctrl_regs.c b/drivers/ddr/fsl/ctrl_regs.c
index 5acbc73..0882932 100644
--- a/drivers/ddr/fsl/ctrl_regs.c
+++ b/drivers/ddr/fsl/ctrl_regs.c
@@ -145,6 +145,7 @@
 			if (!popts->memctl_interleaving)
 				break;
 			switch (popts->memctl_interleaving_mode) {
+			case FSL_DDR_256B_INTERLEAVING:
 			case FSL_DDR_CACHE_LINE_INTERLEAVING:
 			case FSL_DDR_PAGE_INTERLEAVING:
 			case FSL_DDR_BANK_INTERLEAVING:
diff --git a/drivers/ddr/fsl/main.c b/drivers/ddr/fsl/main.c
index dee50a0..d62ca63 100644
--- a/drivers/ddr/fsl/main.c
+++ b/drivers/ddr/fsl/main.c
@@ -291,6 +291,7 @@
 		for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
 			if (pinfo->memctl_opts[i].memctl_interleaving) {
 				switch (pinfo->memctl_opts[i].memctl_interleaving_mode) {
+				case FSL_DDR_256B_INTERLEAVING:
 				case FSL_DDR_CACHE_LINE_INTERLEAVING:
 				case FSL_DDR_PAGE_INTERLEAVING:
 				case FSL_DDR_BANK_INTERLEAVING:
diff --git a/drivers/ddr/fsl/options.c b/drivers/ddr/fsl/options.c
index 4aafcce..b0cf046 100644
--- a/drivers/ddr/fsl/options.c
+++ b/drivers/ddr/fsl/options.c
@@ -818,21 +818,33 @@
 	 * If memory controller interleaving is enabled, then the data
 	 * bus widths must be programmed identically for all memory controllers.
 	 *
-	 * XXX: Attempt to set all controllers to the same chip select
+	 * Attempt to set all controllers to the same chip select
 	 * interleaving mode. It will do a best effort to get the
 	 * requested ranks interleaved together such that the result
 	 * should be a subset of the requested configuration.
+	 *
+	 * if CONFIG_SYS_FSL_DDR_INTLV_256B is defined, mandatory interleaving
+	 * with 256 Byte is enabled.
 	 */
 #if (CONFIG_NUM_DDR_CONTROLLERS > 1)
 	if (!hwconfig_sub_f("fsl_ddr", "ctlr_intlv", buf))
+#ifdef CONFIG_SYS_FSL_DDR_INTLV_256B
+		;
+#else
 		goto done;
-
+#endif
 	if (pdimm[0].n_ranks == 0) {
 		printf("There is no rank on CS0 for controller %d.\n", ctrl_num);
 		popts->memctl_interleaving = 0;
 		goto done;
 	}
 	popts->memctl_interleaving = 1;
+#ifdef CONFIG_SYS_FSL_DDR_INTLV_256B
+	popts->memctl_interleaving_mode = FSL_DDR_256B_INTERLEAVING;
+	popts->memctl_interleaving = 1;
+	debug("256 Byte interleaving\n");
+	goto done;
+#endif
 	/*
 	 * test null first. if CONFIG_HWCONFIG is not defined
 	 * hwconfig_arg_cmp returns non-zero
@@ -1085,6 +1097,7 @@
 			"Memory controller interleaving disabled.\n");
 	} else {
 		switch (check_intlv) {
+		case FSL_DDR_256B_INTERLEAVING:
 		case FSL_DDR_CACHE_LINE_INTERLEAVING:
 		case FSL_DDR_PAGE_INTERLEAVING:
 		case FSL_DDR_BANK_INTERLEAVING:
diff --git a/drivers/ddr/fsl/util.c b/drivers/ddr/fsl/util.c
index 450a488..ad53658 100644
--- a/drivers/ddr/fsl/util.c
+++ b/drivers/ddr/fsl/util.c
@@ -228,6 +228,9 @@
 		puts("       DDR Controller Interleaving Mode: ");
 
 		switch ((cs0_config >> 24) & 0xf) {
+		case FSL_DDR_256B_INTERLEAVING:
+			puts("256B");
+			break;
 		case FSL_DDR_CACHE_LINE_INTERLEAVING:
 			puts("cache line");
 			break;
diff --git a/include/fsl_ddr_sdram.h b/include/fsl_ddr_sdram.h
index 16cccc7..2a36431 100644
--- a/include/fsl_ddr_sdram.h
+++ b/include/fsl_ddr_sdram.h
@@ -76,6 +76,7 @@
 #define FSL_DDR_PAGE_INTERLEAVING	0x1
 #define FSL_DDR_BANK_INTERLEAVING	0x2
 #define FSL_DDR_SUPERBANK_INTERLEAVING	0x3
+#define FSL_DDR_256B_INTERLEAVING	0x8
 #define FSL_DDR_3WAY_1KB_INTERLEAVING	0xA
 #define FSL_DDR_3WAY_4KB_INTERLEAVING	0xC
 #define FSL_DDR_3WAY_8KB_INTERLEAVING	0xD