mpc85xx/T1040QDS_D4: Add DDR4 support

T1040QDS_D4 is a variant of T1040QDS, with additional circuit to support
DDR4 memory. Tested with MTA9ASF51272AZ-2G1AYESZG.

Signed-off-by: York Sun <yorksun@freescale.com>
diff --git a/board/freescale/t1040qds/ddr.c b/board/freescale/t1040qds/ddr.c
index da89a36..43f952f 100644
--- a/board/freescale/t1040qds/ddr.c
+++ b/board/freescale/t1040qds/ddr.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 Freescale Semiconductor, Inc.
+ * Copyright 2013-2014 Freescale Semiconductor, Inc.
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
@@ -39,14 +39,10 @@
 		if (pbsp->n_ranks == pdimm->n_ranks &&
 		    (pdimm->rank_density >> 30) >= pbsp->rank_gb) {
 			if (ddr_freq <= pbsp->datarate_mhz_high) {
-				popts->cpo_override = pbsp->cpo;
-				popts->write_data_delay =
-					pbsp->write_data_delay;
 				popts->clk_adjust = pbsp->clk_adjust;
 				popts->wrlvl_start = pbsp->wrlvl_start;
 				popts->wrlvl_ctl_2 = pbsp->wrlvl_ctl_2;
 				popts->wrlvl_ctl_3 = pbsp->wrlvl_ctl_3;
-				popts->twot_en = pbsp->force_2t;
 				goto found;
 			}
 			pbsp_highest = pbsp;
@@ -59,13 +55,10 @@
 		printf("for data rate %lu MT/s\n", ddr_freq);
 		printf("Trying to use the highest speed (%u) parameters\n",
 		       pbsp_highest->datarate_mhz_high);
-		popts->cpo_override = pbsp_highest->cpo;
-		popts->write_data_delay = pbsp_highest->write_data_delay;
 		popts->clk_adjust = pbsp_highest->clk_adjust;
 		popts->wrlvl_start = pbsp_highest->wrlvl_start;
 		popts->wrlvl_ctl_2 = pbsp->wrlvl_ctl_2;
 		popts->wrlvl_ctl_3 = pbsp->wrlvl_ctl_3;
-		popts->twot_en = pbsp_highest->force_2t;
 	} else {
 		panic("DIMM is not supported by this board");
 	}
@@ -81,7 +74,7 @@
 	 * Factors to consider for half-strength driver enable:
 	 *	- number of DIMMs installed
 	 */
-	popts->half_strength_driver_enable = 0;
+	popts->half_strength_driver_enable = 1;
 	/*
 	 * Write leveling override
 	 */
@@ -97,8 +90,14 @@
 	popts->zq_en = 1;
 
 	/* DHC_EN =1, ODT = 75 Ohm */
+#ifdef CONFIG_SYS_FSL_DDR4
+	popts->ddr_cdr1 = DDR_CDR1_DHC_EN | DDR_CDR1_ODT(DDR_CDR_ODT_80ohm);
+	popts->ddr_cdr2 = DDR_CDR2_ODT(DDR_CDR_ODT_80ohm) |
+			  DDR_CDR2_VREF_OVRD(70);	/* Vref = 70% */
+#else
 	popts->ddr_cdr1 = DDR_CDR1_DHC_EN | DDR_CDR1_ODT(DDR_CDR_ODT_75ohm);
 	popts->ddr_cdr2 = DDR_CDR2_ODT(DDR_CDR_ODT_75ohm);
+#endif
 }
 
 phys_size_t initdram(int board_type)