ppc4xx: IBM Memory Controller DDR autocalibration routines

Alternate SDRAM DDR autocalibration routine that can be generically used
for any PPC4xx chips that have the IBM SDRAM Controller core allowing for
support of more DIMM/memory chip vendors and gets the DDR autocalibration
values which give the best read latency performance (SDRAM0_RDCC.[RDSS]).

Two alternate SDRAM DDR autocalibration algoritm are provided in this patch,
"Method_A" and "Method_B".  DDR autocalibration Method_A scans the full range
of possible PPC4xx  SDRAM Controller DDR autocalibration values and takes a
lot longer to run than Method_B.  Method_B executes in the same amount of time
as the currently existing DDR autocalibration routine, i.e. 1 second or so.
Normally Method_B is used and it is set as the default method.

The current U-Boot PPC4xx DDR autocalibration code calibrates the IBM SDRAM
Controller registers.[bit-field]:
1)  SDRAM0_RQDC.[RQFD]
2)  SDRAM0_RFDC.[RFFD]

This alternate PPC4xx DDR autocalibration code calibrates the following
IBM SDRAM Controller registers.[bit-field]:

1)  SDRAM0_WRDTR.[WDTR]
2)  SDRAM0_CLKTR.[CKTR]
3)  SDRAM0_RQDC.[RQFD]
4)  SDRAM0_RFDC.[RFFD]

and will also use the calibrated settings of the above four registers that
produce the best "Read Sample Cycle Select" value in the SDRAM0_RDCC.[RDSS]
register.[bit-field].

Signed-off-by: Adam Graham <agraham@amcc.com>
Signed-off-by: Stefan Roese <sr@denx.de>

1 files changed, 1212 insertions, 0 deletions

diff --git a/cpu/ppc4xx/4xx_ibm_ddr2_autocalib.c b/cpu/ppc4xx/4xx_ibm_ddr2_autocalib.c
new file mode 100644
index 0000000000..83b9883a77
--- /dev/null
+++ b/cpu/ppc4xx/4xx_ibm_ddr2_autocalib.c
@@ -0,0 +1,1212 @@
+/*
+ * cpu/ppc4xx/4xx_ibm_ddr2_autocalib.c
+ * This SPD SDRAM detection code supports AMCC PPC44x cpu's with a
+ * DDR2 controller (non Denali Core). Those currently are:
+ *
+ * 405:		405EX
+ * 440/460:	440SP/440SPe/460EX/460GT/460SX
+ *
+ * (C) Copyright 2008 Applied Micro Circuits Corporation
+ * Adam Graham  <agraham@amcc.com>
+ *
+ * (C) Copyright 2007-2008
+ * Stefan Roese, DENX Software Engineering, sr@denx.de.
+ *
+ * COPYRIGHT   AMCC   CORPORATION 2004
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ */
+
+/* define DEBUG for debugging output (obviously ;-)) */
+#undef DEBUG
+
+#include <common.h>
+#include <ppc4xx.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+
+#if defined(CONFIG_PPC4xx_DDR_AUTOCALIBRATION)
+
+/*
+ * Only compile the DDR auto-calibration code for NOR boot and
+ * not for NAND boot (NAND SPL and NAND U-Boot - NUB)
+ */
+#if !defined(CONFIG_NAND_U_BOOT) && !defined(CONFIG_NAND_SPL)
+
+#define MAXBXCF			4
+#define SDRAM_RXBAS_SHIFT_1M	20
+
+#if defined(CFG_DECREMENT_PATTERNS)
+#define NUMMEMTESTS		24
+#else
+#define NUMMEMTESTS		8
+#endif /* CFG_DECREMENT_PATTERNS */
+#define NUMLOOPS		1	/* configure as you deem approporiate */
+#define NUMMEMWORDS		16
+
+/* Private Structure Definitions */
+
+struct autocal_regs {
+	u32 rffd;
+	u32 rqfd;
+};
+
+struct ddrautocal {
+	u32 rffd;
+	u32 rffd_min;
+	u32 rffd_max;
+	u32 rffd_size;
+	u32 rqfd;
+	u32 rqfd_size;
+	u32 rdcc;
+	u32 flags;
+};
+
+struct sdram_timing {
+	u32 wrdtr;
+	u32 clktr;
+};
+
+struct sdram_timing_clks {
+	u32 wrdtr;
+	u32 clktr;
+	u32 rdcc;
+	u32 flags;
+};
+
+struct autocal_clks {
+	struct sdram_timing_clks clocks;
+	struct ddrautocal	 autocal;
+};
+
+/*--------------------------------------------------------------------------+
+ * Prototypes
+ *--------------------------------------------------------------------------*/
+#if defined(CONFIG_PPC4xx_DDR_METHOD_A)
+static u32 DQS_calibration_methodA(struct ddrautocal *);
+static u32 program_DQS_calibration_methodA(struct ddrautocal *);
+#else
+static u32 DQS_calibration_methodB(struct ddrautocal *);
+static u32 program_DQS_calibration_methodB(struct ddrautocal *);
+#endif
+static int short_mem_test(u32 *);
+
+/*
+ * To provide an interface for board specific config values in this common
+ * DDR setup code, we implement he "weak" default functions here. They return
+ * the default value back to the caller.
+ *
+ * Please see include/configs/yucca.h for an example fora board specific
+ * implementation.
+ */
+
+#if !defined(CONFIG_SPD_EEPROM)
+u32 __ddr_wrdtr(u32 default_val)
+{
+	return default_val;
+}
+u32 ddr_wrdtr(u32) __attribute__((weak, alias("__ddr_wrdtr")));
+
+u32 __ddr_clktr(u32 default_val)
+{
+	return default_val;
+}
+u32 ddr_clktr(u32) __attribute__((weak, alias("__ddr_clktr")));
+
+/*
+ * Board-specific Platform code can reimplement spd_ddr_init_hang () if needed
+ */
+void __spd_ddr_init_hang(void)
+{
+	hang();
+}
+void
+spd_ddr_init_hang(void) __attribute__((weak, alias("__spd_ddr_init_hang")));
+#endif /* defined(CONFIG_SPD_EEPROM) */
+
+ulong __ddr_scan_option(ulong default_val)
+{
+	return default_val;
+}
+ulong ddr_scan_option(ulong) __attribute__((weak, alias("__ddr_scan_option")));
+
+static u32 *get_membase(int bxcr_num)
+{
+	ulong bxcf;
+	u32 *membase;
+
+#if defined(SDRAM_R0BAS)
+	/* BAS from Memory Queue rank reg. */
+	membase =
+	    (u32 *)(SDRAM_RXBAS_SDBA_DECODE(mfdcr_any(SDRAM_R0BAS+bxcr_num)));
+	bxcf = 0;	/* just to satisfy the compiler */
+#else
+	/* BAS from SDRAM_MBxCF mem rank reg. */
+	mfsdram(SDRAM_MB0CF + (bxcr_num<<2), bxcf);
+	membase = (u32 *)((bxcf & 0xfff80000) << 3);
+#endif
+
+	return membase;
+}
+
+static inline void ecc_clear_status_reg(void)
+{
+	mtsdram(SDRAM_ECCCR, 0xffffffff);
+#if defined(SDRAM_R0BAS)
+	mtdcr(SDRAM_ERRSTATLL, 0xffffffff);
+#endif
+}
+
+static int ecc_check_status_reg(void)
+{
+	u32 ecc_status;
+
+	/*
+	 * Compare suceeded, now check
+	 * if got ecc error. If got an
+	 * ecc error, then don't count
+	 * this as a passing value
+	 */
+	mfsdram(SDRAM_ECCCR, ecc_status);
+	if (ecc_status != 0x00000000) {
+		/* clear on error */
+		ecc_clear_status_reg();
+		/* ecc check failure */
+		return 0;
+	}
+	ecc_clear_status_reg();
+	sync();
+
+	return 1;
+}
+
+/* return 1 if passes, 0 if fail */
+static int short_mem_test(u32 *base_address)
+{
+	int i, j, l;
+	u32 ecc_mode = 0;
+
+	ulong test[NUMMEMTESTS][NUMMEMWORDS] = {
+	/* 0 */	{0x00000000, 0x00000000, 0xFFFFFFFF, 0xFFFFFFFF,
+		 0x00000000, 0x00000000, 0xFFFFFFFF, 0xFFFFFFFF,
+		 0x00000000, 0x00000000, 0xFFFFFFFF, 0xFFFFFFFF,
+		 0x00000000, 0x00000000, 0xFFFFFFFF, 0xFFFFFFFF},
+	/* 1 */	{0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000,
+		 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000,
+		 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000,
+		 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000},
+	/* 2 */	{0xAAAAAAAA, 0xAAAAAAAA, 0x55555555, 0x55555555,
+		 0xAAAAAAAA, 0xAAAAAAAA, 0x55555555, 0x55555555,
+		 0xAAAAAAAA, 0xAAAAAAAA, 0x55555555, 0x55555555,
+		 0xAAAAAAAA, 0xAAAAAAAA, 0x55555555, 0x55555555},
+	/* 3 */	{0x55555555, 0x55555555, 0xAAAAAAAA, 0xAAAAAAAA,
+		 0x55555555, 0x55555555, 0xAAAAAAAA, 0xAAAAAAAA,
+		 0x55555555, 0x55555555, 0xAAAAAAAA, 0xAAAAAAAA,
+		 0x55555555, 0x55555555, 0xAAAAAAAA, 0xAAAAAAAA},
+	/* 4 */	{0xA5A5A5A5, 0xA5A5A5A5, 0x5A5A5A5A, 0x5A5A5A5A,
+		 0xA5A5A5A5, 0xA5A5A5A5, 0x5A5A5A5A, 0x5A5A5A5A,
+		 0xA5A5A5A5, 0xA5A5A5A5, 0x5A5A5A5A, 0x5A5A5A5A,
+		 0xA5A5A5A5, 0xA5A5A5A5, 0x5A5A5A5A, 0x5A5A5A5A},
+	/* 5 */	{0x5A5A5A5A, 0x5A5A5A5A, 0xA5A5A5A5, 0xA5A5A5A5,
+		 0x5A5A5A5A, 0x5A5A5A5A, 0xA5A5A5A5, 0xA5A5A5A5,
+		 0x5A5A5A5A, 0x5A5A5A5A, 0xA5A5A5A5, 0xA5A5A5A5,
+		 0x5A5A5A5A, 0x5A5A5A5A, 0xA5A5A5A5, 0xA5A5A5A5},
+	/* 6 */	{0xAA55AA55, 0xAA55AA55, 0x55AA55AA, 0x55AA55AA,
+		 0xAA55AA55, 0xAA55AA55, 0x55AA55AA, 0x55AA55AA,
+		 0xAA55AA55, 0xAA55AA55, 0x55AA55AA, 0x55AA55AA,
+		 0xAA55AA55, 0xAA55AA55, 0x55AA55AA, 0x55AA55AA},
+	/* 7 */	{0x55AA55AA, 0x55AA55AA, 0xAA55AA55, 0xAA55AA55,
+		 0x55AA55AA, 0x55AA55AA, 0xAA55AA55, 0xAA55AA55,
+		 0x55AA55AA, 0x55AA55AA, 0xAA55AA55, 0xAA55AA55,
+		 0x55AA55AA, 0x55AA55AA, 0xAA55AA55, 0xAA55AA55},
+
+#if defined(CFG_DECREMENT_PATTERNS)
+	/* 8 */	{0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff,
+		 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff,
+		 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff,
+		 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff},
+	/* 9 */	{0xfffefffe, 0xfffefffe, 0xfffefffe, 0xfffefffe,
+		 0xfffefffe, 0xfffefffe, 0xfffefffe, 0xfffefffe,
+		 0xfffefffe, 0xfffefffe, 0xfffefffe, 0xfffefffe,
+		 0xfffefffe, 0xfffefffe, 0xfffefffe, 0xfffefffe},
+	/* 10 */{0xfffdfffd, 0xfffdfffd, 0xfffdffff, 0xfffdfffd,
+		 0xfffdfffd, 0xfffdfffd, 0xfffdffff, 0xfffdfffd,
+		 0xfffdfffd, 0xfffdfffd, 0xfffdffff, 0xfffdfffd,
+		 0xfffdfffd, 0xfffdfffd, 0xfffdffff, 0xfffdfffd},
+	/* 11 */{0xfffcfffc, 0xfffcfffc, 0xfffcfffc, 0xfffcfffc,
+		 0xfffcfffc, 0xfffcfffc, 0xfffcfffc, 0xfffcfffc,
+		 0xfffcfffc, 0xfffcfffc, 0xfffcfffc, 0xfffcfffc,
+		 0xfffcfffc, 0xfffcfffc, 0xfffcfffc, 0xfffcfffc},
+	/* 12 */{0xfffbfffb, 0xfffffffb, 0xfffffffb, 0xfffffffb,
+		 0xfffbfffb, 0xfffffffb, 0xfffffffb, 0xfffffffb,
+		 0xfffbfffb, 0xfffffffb, 0xfffffffb, 0xfffffffb,
+		 0xfffbfffb, 0xfffffffb, 0xfffffffb, 0xfffffffb},
+	/* 13 */{0xfffafffa, 0xfffafffa, 0xfffffffa, 0xfffafffa,
+		 0xfffafffa, 0xfffafffa, 0xfffafffa, 0xfffafffa,
+		 0xfffafffa, 0xfffafffa, 0xfffafffa, 0xfffafffa,
+		 0xfffafffa, 0xfffafffa, 0xfffafffa, 0xfffafffa},
+	/* 14 */{0xfff9fff9, 0xfff9fff9, 0xfff9fff9, 0xfff9fff9,
+		 0xfff9fff9, 0xfff9fff9, 0xfff9fff9, 0xfff9fff9,
+		 0xfff9fff9, 0xfff9fff9, 0xfff9fff9, 0xfff9fff9,
+		 0xfff9fff9, 0xfff9fff9, 0xfff9fff9, 0xfff9fff9},
+	/* 15 */{0xfff8fff8, 0xfff8fff8, 0xfff8fff8, 0xfff8fff8,
+		 0xfff8fff8, 0xfff8fff8, 0xfff8fff8, 0xfff8fff8,
+		 0xfff8fff8, 0xfff8fff8, 0xfff8fff8, 0xfff8fff8,
+		 0xfff8fff8, 0xfff8fff8, 0xfff8fff8, 0xfff8fff8},
+	/* 16 */{0xfff7fff7, 0xfff7ffff, 0xfff7fff7, 0xfff7fff7,
+		 0xfff7fff7, 0xfff7ffff, 0xfff7fff7, 0xfff7fff7,
+		 0xfff7fff7, 0xfff7ffff, 0xfff7fff7, 0xfff7fff7,
+		 0xfff7ffff, 0xfff7ffff, 0xfff7fff7, 0xfff7fff7},
+	/* 17 */{0xfff6fff5, 0xfff6ffff, 0xfff6fff6, 0xfff6fff7,
+		 0xfff6fff5, 0xfff6ffff, 0xfff6fff6, 0xfff6fff7,
+		 0xfff6fff5, 0xfff6ffff, 0xfff6fff6, 0xfff6fff7,
+		 0xfff6fff5, 0xfff6ffff, 0xfff6fff6, 0xfff6fff7},
+	/* 18 */{0xfff5fff4, 0xfff5ffff, 0xfff5fff5, 0xfff5fff5,
+		 0xfff5fff4, 0xfff5ffff, 0xfff5fff5, 0xfff5fff5,
+		 0xfff5fff4, 0xfff5ffff, 0xfff5fff5, 0xfff5fff5,
+		 0xfff5fff4, 0xfff5ffff, 0xfff5fff5, 0xfff5fff5},
+	/* 19 */{0xfff4fff3, 0xfff4ffff, 0xfff4fff4, 0xfff4fff4,
+		 0xfff4fff3, 0xfff4ffff, 0xfff4fff4, 0xfff4fff4,
+		 0xfff4fff3, 0xfff4ffff, 0xfff4fff4, 0xfff4fff4,
+		 0xfff4fff3, 0xfff4ffff, 0xfff4fff4, 0xfff4fff4},
+	/* 20 */{0xfff3fff2, 0xfff3ffff, 0xfff3fff3, 0xfff3fff3,
+		 0xfff3fff2, 0xfff3ffff, 0xfff3fff3, 0xfff3fff3,
+		 0xfff3fff2, 0xfff3ffff, 0xfff3fff3, 0xfff3fff3,
+		 0xfff3fff2, 0xfff3ffff, 0xfff3fff3, 0xfff3fff3},
+	/* 21 */{0xfff2ffff, 0xfff2ffff, 0xfff2fff2, 0xfff2fff2,
+		 0xfff2ffff, 0xfff2ffff, 0xfff2fff2, 0xfff2fff2,
+		 0xfff2ffff, 0xfff2ffff, 0xfff2fff2, 0xfff2fff2,
+		 0xfff2ffff, 0xfff2ffff, 0xfff2fff2, 0xfff2fff2},
+	/* 22 */{0xfff1ffff, 0xfff1ffff, 0xfff1fff1, 0xfff1fff1,
+		 0xfff1ffff, 0xfff1ffff, 0xfff1fff1, 0xfff1fff1,
+		 0xfff1ffff, 0xfff1ffff, 0xfff1fff1, 0xfff1fff1,
+		 0xfff1ffff, 0xfff1ffff, 0xfff1fff1, 0xfff1fff1},
+	/* 23 */{0xfff0fff0, 0xfff0fff0, 0xfff0fff0, 0xfff0fff0,
+		 0xfff0fff0, 0xfff0fff0, 0xfff0fff0, 0xfff0fff0,
+		 0xfff0fff0, 0xfff0fff0, 0xfff0fff0, 0xfff0fff0,
+		 0xfff0fff0, 0xfff0fffe, 0xfff0fff0, 0xfff0fff0},
+#endif /* CFG_DECREMENT_PATTERNS */
+								 };
+
+	mfsdram(SDRAM_MCOPT1, ecc_mode);
+	if ((ecc_mode & SDRAM_MCOPT1_MCHK_CHK_REP) ==
+						SDRAM_MCOPT1_MCHK_CHK_REP) {
+		ecc_clear_status_reg();
+		sync();
+		ecc_mode = 1;
+	} else {
+		ecc_mode = 0;
+	}
+
+	/*
+	 * Run the short memory test.
+	 */
+	for (i = 0; i < NUMMEMTESTS; i++) {
+		for (j = 0; j < NUMMEMWORDS; j++) {
+			base_address[j] = test[i][j];
+			ppcDcbf((ulong)&(base_address[j]));
+		}
+		sync();
+		for (l = 0; l < NUMLOOPS; l++) {
+			for (j = 0; j < NUMMEMWORDS; j++) {
+				if (base_address[j] != test[i][j]) {
+					ppcDcbf((u32)&(base_address[j]));
+					return 0;
+				} else {
+					if (ecc_mode) {
+						if (!ecc_check_status_reg())
+							return 0;
+					}
+				}
+				ppcDcbf((u32)&(base_address[j]));
+			} /* for (j = 0; j < NUMMEMWORDS; j++) */
+			sync();
+		} /* for (l=0; l<NUMLOOPS; l++) */
+	}
+
+	return 1;
+}
+
+#if defined(CONFIG_PPC4xx_DDR_METHOD_A)
+/*-----------------------------------------------------------------------------+
+| program_DQS_calibration_methodA.
++-----------------------------------------------------------------------------*/
+static u32 program_DQS_calibration_methodA(struct ddrautocal *ddrcal)
+{
+	u32 pass_result = 0;
+
+#ifdef DEBUG
+	ulong temp;
+
+	mfsdram(SDRAM_RDCC, temp);
+	debug("<%s>SDRAM_RDCC=0x%08x\n", __func__, temp);
+#endif
+
+	pass_result = DQS_calibration_methodA(ddrcal);
+
+	return pass_result;
+}
+
+/*
+ * DQS_calibration_methodA()
+ *
+ * Autocalibration Method A
+ *
+ *  ARRAY [Entire DQS Range] DQS_Valid_Window ;    initialized to all zeros
+ *  ARRAY [Entire FDBK Range] FDBK_Valid_Window;   initialized to all zeros
+ *  MEMWRITE(addr, expected_data);
+ *  for (i = 0; i < Entire DQS Range; i++) {       RQDC.RQFD
+ *      for (j = 0; j < Entire FDBK Range; j++) {  RFDC.RFFD
+ *         MEMREAD(addr, actual_data);
+ *         if (actual_data == expected_data) {
+ *             DQS_Valid_Window[i] = 1;            RQDC.RQFD
+ *             FDBK_Valid_Window[i][j] = 1;        RFDC.RFFD
+ *         }
+ *      }
+ *  }
+ */
+static u32 DQS_calibration_methodA(struct ddrautocal *cal)
+{
+	ulong rfdc_reg;
+	ulong rffd;
+
+	ulong rqdc_reg;
+	ulong rqfd;
+
+	u32 *membase;
+	ulong bxcf;
+	int rqfd_average;
+	int bxcr_num;
+	int rffd_average;
+	int pass;
+	u32 passed = 0;
+
+	int in_window;
+	struct autocal_regs curr_win_min;
+	struct autocal_regs curr_win_max;
+	struct autocal_regs best_win_min;
+	struct autocal_regs best_win_max;
+	struct autocal_regs loop_win_min;
+	struct autocal_regs loop_win_max;
+
+#ifdef DEBUG
+	ulong temp;
+#endif
+	ulong rdcc;
+
+	char slash[] = "\\|/-\\|/-";
+	int loopi = 0;
+
+	/* start */
+	in_window = 0;
+
+	memset(&curr_win_min, 0, sizeof(curr_win_min));
+	memset(&curr_win_max, 0, sizeof(curr_win_max));
+	memset(&best_win_min, 0, sizeof(best_win_min));
+	memset(&best_win_max, 0, sizeof(best_win_max));
+	memset(&loop_win_min, 0, sizeof(loop_win_min));
+	memset(&loop_win_max, 0, sizeof(loop_win_max));
+
+	rdcc = 0;
+
+	/*
+	 * Program RDCC register
+	 * Read sample cycle auto-update enable
+	 */
+	mtsdram(SDRAM_RDCC, SDRAM_RDCC_RDSS_T1 | SDRAM_RDCC_RSAE_ENABLE);
+
+#ifdef DEBUG
+	mfsdram(SDRAM_RDCC, temp);
+	debug("<%s>SDRAM_RDCC=0x%x\n", __func__, temp);
+	mfsdram(SDRAM_RTSR, temp);
+	debug("<%s>SDRAM_RTSR=0x%x\n", __func__, temp);
+	mfsdram(SDRAM_FCSR, temp);
+	debug("<%s>SDRAM_FCSR=0x%x\n", __func__, temp);
+#endif
+
+	/*
+	 * Program RQDC register
+	 * Internal DQS delay mechanism enable
+	 */
+	mtsdram(SDRAM_RQDC,
+		SDRAM_RQDC_RQDE_ENABLE | SDRAM_RQDC_RQFD_ENCODE(0x00));
+
+#ifdef DEBUG
+	mfsdram(SDRAM_RQDC, temp);
+	debug("<%s>SDRAM_RQDC=0x%x\n", __func__, temp);
+#endif
+
+	/*
+	 * Program RFDC register
+	 * Set Feedback Fractional Oversample
+	 * Auto-detect read sample cycle enable
+	 */
+	mtsdram(SDRAM_RFDC, SDRAM_RFDC_ARSE_ENABLE |
+		SDRAM_RFDC_RFOS_ENCODE(0) | SDRAM_RFDC_RFFD_ENCODE(0));
+
+#ifdef DEBUG
+	mfsdram(SDRAM_RFDC, temp);
+	debug("<%s>SDRAM_RFDC=0x%x\n", __func__, temp);
+#endif
+
+	putc(' ');
+	for (rqfd = 0; rqfd <= SDRAM_RQDC_RQFD_MAX; rqfd++) {
+
+		mfsdram(SDRAM_RQDC, rqdc_reg);
+		rqdc_reg &= ~(SDRAM_RQDC_RQFD_MASK);
+		mtsdram(SDRAM_RQDC, rqdc_reg | SDRAM_RQDC_RQFD_ENCODE(rqfd));
+
+		putc('\b');
+		putc(slash[loopi++ % 8]);
+
+		curr_win_min.rffd = 0;
+		curr_win_max.rffd = 0;
+		in_window = 0;
+
+		for (rffd = 0, pass = 0; rffd <= SDRAM_RFDC_RFFD_MAX; rffd++) {
+			mfsdram(SDRAM_RFDC, rfdc_reg);
+			rfdc_reg &= ~(SDRAM_RFDC_RFFD_MASK);
+			mtsdram(SDRAM_RFDC,
+				    rfdc_reg | SDRAM_RFDC_RFFD_ENCODE(rffd));
+
+			for (bxcr_num = 0; bxcr_num < MAXBXCF; bxcr_num++) {
+				mfsdram(SDRAM_MB0CF + (bxcr_num<<2), bxcf);
+
+				/* Banks enabled */
+				if (bxcf & SDRAM_BXCF_M_BE_MASK) {
+					/* Bank is enabled */
+					membase = get_membase(bxcr_num);
+					pass = short_mem_test(membase);
+				} /* if bank enabled */
+			} /* for bxcr_num */
+
+			/* If this value passed update RFFD windows */
+			if (pass && !in_window) { /* at the start of window */
+				in_window = 1;
+				curr_win_min.rffd = curr_win_max.rffd = rffd;
+				curr_win_min.rqfd = curr_win_max.rqfd = rqfd;
+				mfsdram(SDRAM_RDCC, rdcc); /*record this value*/
+			} else if (!pass && in_window) { /* at end of window */
+				in_window = 0;
+			} else if (pass && in_window) { /* within the window */
+				curr_win_max.rffd = rffd;
+				curr_win_max.rqfd = rqfd;
+			}
+			/* else if (!pass && !in_window)
+				skip - no pass, not currently in a window */
+
+			if (in_window) {
+				if ((curr_win_max.rffd - curr_win_min.rffd) >
+				    (best_win_max.rffd - best_win_min.rffd)) {
+					best_win_min.rffd = curr_win_min.rffd;
+					best_win_max.rffd = curr_win_max.rffd;
+
+					best_win_min.rqfd = curr_win_min.rqfd;
+					best_win_max.rqfd = curr_win_max.rqfd;
+					cal->rdcc	  = rdcc;
+				}
+				passed = 1;
+			}
+		} /* RFDC.RFFD */
+
+		/*
+		 * save-off the best window results of the RFDC.RFFD
+		 * for this RQDC.RQFD setting
+		 */
+		/*
+		 * if (just ended RFDC.RFDC loop pass window) >
+		 *	(prior RFDC.RFFD loop pass window)
+		 */
+		if ((best_win_max.rffd - best_win_min.rffd) >
+		    (loop_win_max.rffd - loop_win_min.rffd)) {
+			loop_win_min.rffd = best_win_min.rffd;
+			loop_win_max.rffd = best_win_max.rffd;
+			loop_win_min.rqfd = rqfd;
+			loop_win_max.rqfd = rqfd;
+			debug("RQFD.min 0x%08x, RQFD.max 0x%08x, "
+			      "RFFD.min 0x%08x, RFFD.max 0x%08x\n",
+					loop_win_min.rqfd, loop_win_max.rqfd,
+					loop_win_min.rffd, loop_win_max.rffd);
+		}
+	} /* RQDC.RQFD */
+
+	putc('\b');
+
+	debug("\n");
+
+	if ((loop_win_min.rffd == 0) && (loop_win_max.rffd == 0) &&
+	    (best_win_min.rffd == 0) && (best_win_max.rffd == 0) &&
+	    (best_win_min.rqfd == 0) && (best_win_max.rqfd == 0)) {
+		passed = 0;
+	}
+
+	/*
+	 * Need to program RQDC before RFDC.
+	 */
+	debug("<%s> RQFD Min: 0x%x\n", __func__, loop_win_min.rqfd);
+	debug("<%s> RQFD Max: 0x%x\n", __func__, loop_win_max.rqfd);
+	rqfd_average = loop_win_max.rqfd;
+
+	if (rqfd_average < 0)
+		rqfd_average = 0;
+
+	if (rqfd_average > SDRAM_RQDC_RQFD_MAX)
+		rqfd_average = SDRAM_RQDC_RQFD_MAX;
+
+	debug("<%s> RFFD average: 0x%08x\n", __func__, rqfd_average);
+	mtsdram(SDRAM_RQDC, (rqdc_reg & ~SDRAM_RQDC_RQFD_MASK) |
+				SDRAM_RQDC_RQFD_ENCODE(rqfd_average));
+
+	debug("<%s> RFFD Min: 0x%08x\n", __func__, loop_win_min.rffd);
+	debug("<%s> RFFD Max: 0x%08x\n", __func__, loop_win_max.rffd);
+	rffd_average = ((loop_win_min.rffd + loop_win_max.rffd) / 2);
+
+	if (rffd_average < 0)
+		rffd_average = 0;
+
+	if (rffd_average > SDRAM_RFDC_RFFD_MAX)
+		rffd_average = SDRAM_RFDC_RFFD_MAX;
+
+	debug("<%s> RFFD average: 0x%08x\n", __func__, rffd_average);
+	mtsdram(SDRAM_RFDC, rfdc_reg | SDRAM_RFDC_RFFD_ENCODE(rffd_average));
+
+	/* if something passed, then return the size of the largest window */
+	if (passed != 0) {
+		passed		= loop_win_max.rffd - loop_win_min.rffd;
+		cal->rqfd	= rqfd_average;
+		cal->rffd	= rffd_average;
+		cal->rffd_min	= loop_win_min.rffd;
+		cal->rffd_max	= loop_win_max.rffd;
+	}
+
+	return (u32)passed;
+}
+
+#else	/* !defined(CONFIG_PPC4xx_DDR_METHOD_A) */
+
+/*-----------------------------------------------------------------------------+
+| program_DQS_calibration_methodB.
++-----------------------------------------------------------------------------*/
+static u32 program_DQS_calibration_methodB(struct ddrautocal *ddrcal)
+{
+	u32 pass_result = 0;
+
+#ifdef DEBUG
+	ulong temp;
+#endif
+
+	/*
+	 * Program RDCC register
+	 * Read sample cycle auto-update enable
+	 */
+	mtsdram(SDRAM_RDCC, SDRAM_RDCC_RDSS_T2 | SDRAM_RDCC_RSAE_ENABLE);
+
+#ifdef DEBUG
+	mfsdram(SDRAM_RDCC, temp);
+	debug("<%s>SDRAM_RDCC=0x%08x\n", __func__, temp);
+#endif
+
+	/*
+	 * Program RQDC register
+	 * Internal DQS delay mechanism enable
+	 */
+	mtsdram(SDRAM_RQDC,
+#if defined(CONFIG_DDR_RQDC_START_VAL)
+			SDRAM_RQDC_RQDE_ENABLE |
+			    SDRAM_RQDC_RQFD_ENCODE(CONFIG_DDR_RQDC_START_VAL));
+#else
+			SDRAM_RQDC_RQDE_ENABLE | SDRAM_RQDC_RQFD_ENCODE(0x38));
+#endif
+
+#ifdef DEBUG
+	mfsdram(SDRAM_RQDC, temp);
+	debug("<%s>SDRAM_RQDC=0x%08x\n", __func__, temp);
+#endif
+
+	/*
+	 * Program RFDC register
+	 * Set Feedback Fractional Oversample
+	 * Auto-detect read sample cycle enable
+	 */
+	mtsdram(SDRAM_RFDC,	SDRAM_RFDC_ARSE_ENABLE |
+				SDRAM_RFDC_RFOS_ENCODE(0) |
+				SDRAM_RFDC_RFFD_ENCODE(0));
+
+#ifdef DEBUG
+	mfsdram(SDRAM_RFDC, temp);
+	debug("<%s>SDRAM_RFDC=0x%08x\n", __func__, temp);
+#endif
+
+	pass_result = DQS_calibration_methodB(ddrcal);
+
+	return pass_result;
+}
+
+/*
+ * DQS_calibration_methodB()
+ *
+ * Autocalibration Method B
+ *
+ * ARRAY [Entire DQS Range] DQS_Valid_Window ;       initialized to all zeros
+ * ARRAY [Entire Feedback Range] FDBK_Valid_Window;  initialized to all zeros
+ * MEMWRITE(addr, expected_data);
+ * Initialialize the DQS delay to 80 degrees (MCIF0_RRQDC[RQFD]=0x38).
+ *
+ *  for (j = 0; j < Entire Feedback Range; j++) {
+ *      MEMREAD(addr, actual_data);
+ *       if (actual_data == expected_data) {
+ *           FDBK_Valid_Window[j] = 1;
+ *       }
+ * }
+ *
+ * Set MCIF0_RFDC[RFFD] to the middle of the FDBK_Valid_Window.
+ *
+ * for (i = 0; i < Entire DQS Range; i++) {
+ *     MEMREAD(addr, actual_data);
+ *     if (actual_data == expected_data) {
+ *         DQS_Valid_Window[i] = 1;
+ *      }
+ * }
+ *
+ * Set MCIF0_RRQDC[RQFD] to the middle of the DQS_Valid_Window.
+ */
+/*-----------------------------------------------------------------------------+
+| DQS_calibration_methodB.
++-----------------------------------------------------------------------------*/
+static u32 DQS_calibration_methodB(struct ddrautocal *cal)
+{
+	ulong rfdc_reg;
+	ulong rffd;
+
+	ulong rqdc_reg;
+	ulong rqfd;
+
+	ulong rdcc;
+
+	u32 *membase;
+	ulong bxcf;
+	int rqfd_average;
+	int bxcr_num;
+	int rffd_average;
+	int pass;
+	uint passed = 0;
+
+	int in_window;
+	u32 curr_win_min, curr_win_max;
+	u32 best_win_min, best_win_max;
+	u32 size = 0;
+
+	/*------------------------------------------------------------------
+	 | Test to determine the best read clock delay tuning bits.
+	 |
+	 | Before the DDR controller can be used, the read clock delay needs to
+	 | be set.  This is SDRAM_RQDC[RQFD] and SDRAM_RFDC[RFFD].
+	 | This value cannot be hardcoded into the program because it changes
+	 | depending on the board's setup and environment.
+	 | To do this, all delay values are tested to see if they
+	 | work or not.  By doing this, you get groups of fails with groups of
+	 | passing values.  The idea is to find the start and end of a passing
+	 | window and take the center of it to use as the read clock delay.
+	 |
+	 | A failure has to be seen first so that when we hit a pass, we know
+	 | that it is truely the start of the window.  If we get passing values
+	 | to start off with, we don't know if we are at the start of the window
+	 |
+	 | The code assumes that a failure will always be found.
+	 | If a failure is not found, there is no easy way to get the middle
+	 | of the passing window.  I guess we can pretty much pick any value
+	 | but some values will be better than others.  Since the lowest speed
+	 | we can clock the DDR interface at is 200 MHz (2x 100 MHz PLB speed),
+	 | from experimentation it is safe to say you will always have a failure
+	 +-----------------------------------------------------------------*/
+
+	debug("\n\n");
+
+	in_window = 0;
+	rdcc = 0;
+
+	curr_win_min = curr_win_max = 0;
+	best_win_min = best_win_max = 0;
+	for (rffd = 0; rffd <= SDRAM_RFDC_RFFD_MAX; rffd++) {
+		mfsdram(SDRAM_RFDC, rfdc_reg);
+		rfdc_reg &= ~(SDRAM_RFDC_RFFD_MASK);
+		mtsdram(SDRAM_RFDC, rfdc_reg | SDRAM_RFDC_RFFD_ENCODE(rffd));
+
+		pass = 1;
+		for (bxcr_num = 0; bxcr_num < MAXBXCF; bxcr_num++) {
+			mfsdram(SDRAM_MB0CF + (bxcr_num<<2), bxcf);
+
+			/* Banks enabled */
+			if (bxcf & SDRAM_BXCF_M_BE_MASK) {
+				/* Bank is enabled */
+				membase = get_membase(bxcr_num);
+				pass &= short_mem_test(membase);
+			} /* if bank enabled */
+		} /* for bxcf_num */
+
+		/* If this value passed */
+		if (pass && !in_window) {	/* start of passing window */
+			in_window = 1;
+			curr_win_min = curr_win_max = rffd;
+			mfsdram(SDRAM_RDCC, rdcc);	/* record this value */
+		} else if (!pass && in_window) {	/* end passing window */
+			in_window = 0;
+		} else if (pass && in_window) {	/* within the passing window */
+			curr_win_max = rffd;
+		}
+
+		if (in_window) {
+			if ((curr_win_max - curr_win_min) >
+			    (best_win_max - best_win_min)) {
+				best_win_min = curr_win_min;
+				best_win_max = curr_win_max;
+				cal->rdcc    = rdcc;
+			}
+			passed = 1;
+		}
+	} /* for rffd */
+
+	if ((best_win_min == 0) && (best_win_max == 0))
+		passed = 0;
+	else
+		size = best_win_max - best_win_min;
+
+	debug("RFFD Min: 0x%x\n", best_win_min);
+	debug("RFFD Max: 0x%x\n", best_win_max);
+	rffd_average = ((best_win_min + best_win_max) / 2);
+
+	cal->rffd_min = best_win_min;
+	cal->rffd_max = best_win_max;
+
+	if (rffd_average < 0)
+		rffd_average = 0;
+
+	if (rffd_average > SDRAM_RFDC_RFFD_MAX)
+		rffd_average = SDRAM_RFDC_RFFD_MAX;
+
+	mtsdram(SDRAM_RFDC, rfdc_reg | SDRAM_RFDC_RFFD_ENCODE(rffd_average));
+
+	rffd = rffd_average;
+	in_window = 0;
+
+	curr_win_min = curr_win_max = 0;
+	best_win_min = best_win_max = 0;
+	for (rqfd = 0; rqfd <= SDRAM_RQDC_RQFD_MAX; rqfd++) {
+		mfsdram(SDRAM_RQDC, rqdc_reg);
+		rqdc_reg &= ~(SDRAM_RQDC_RQFD_MASK);
+		mtsdram(SDRAM_RQDC, rqdc_reg | SDRAM_RQDC_RQFD_ENCODE(rqfd));
+
+		pass = 1;
+		for (bxcr_num = 0; bxcr_num < MAXBXCF; bxcr_num++) {
+
+			mfsdram(SDRAM_MB0CF + (bxcr_num<<2), bxcf);
+
+			/* Banks enabled */
+			if (bxcf & SDRAM_BXCF_M_BE_MASK) {
+				/* Bank is enabled */
+				membase = get_membase(bxcr_num);
+				pass &= short_mem_test(membase);
+			} /* if bank enabled */
+		} /* for bxcf_num */
+
+		/* If this value passed */
+		if (pass && !in_window) {
+			in_window = 1;
+			curr_win_min = curr_win_max = rqfd;
+		} else if (!pass && in_window) {
+			in_window = 0;
+		} else if (pass && in_window) {
+			curr_win_max = rqfd;
+		}
+
+		if (in_window) {
+			if ((curr_win_max - curr_win_min) >
+			    (best_win_max - best_win_min)) {
+				best_win_min = curr_win_min;
+				best_win_max = curr_win_max;
+			}
+			passed = 1;
+		}
+	} /* for rqfd */
+
+	if ((best_win_min == 0) && (best_win_max == 0))
+		passed = 0;
+
+	debug("RQFD Min: 0x%x\n", best_win_min);
+	debug("RQFD Max: 0x%x\n", best_win_max);
+	rqfd_average = ((best_win_min + best_win_max) / 2);
+
+	if (rqfd_average < 0)
+		rqfd_average = 0;
+
+	if (rqfd_average > SDRAM_RQDC_RQFD_MAX)
+		rqfd_average = SDRAM_RQDC_RQFD_MAX;
+
+	mtsdram(SDRAM_RQDC, (rqdc_reg & ~SDRAM_RQDC_RQFD_MASK) |
+					SDRAM_RQDC_RQFD_ENCODE(rqfd_average));
+
+	mfsdram(SDRAM_RQDC, rqdc_reg);
+	mfsdram(SDRAM_RFDC, rfdc_reg);
+
+	/*
+	 * Need to program RQDC before RFDC. The value is read above.
+	 * That is the reason why auto cal not work.
+	 * See, comments below.
+	 */
+	mtsdram(SDRAM_RQDC, rqdc_reg);
+	mtsdram(SDRAM_RFDC, rfdc_reg);
+
+	debug("RQDC: 0x%08X\n", rqdc_reg);
+	debug("RFDC: 0x%08X\n", rfdc_reg);
+
+	/* if something passed, then return the size of the largest window */
+	if (passed != 0) {
+		passed		= size;
+		cal->rqfd	= rqfd_average;
+		cal->rffd	= rffd_average;
+	}
+
+	return (uint)passed;
+}
+#endif /* defined(CONFIG_PPC4xx_DDR_METHOD_A) */
+
+/*
+ * Default table for DDR auto-calibration of all
+ * possible WRDTR and CLKTR values.
+ * Table format is:
+ *	 {SDRAM_WRDTR.[WDTR], SDRAM_CLKTR.[CKTR]}
+ *
+ * Table is terminated with {-1, -1} value pair.
+ *
+ * Board vendors can specify their own board specific subset of
+ * known working {SDRAM_WRDTR.[WDTR], SDRAM_CLKTR.[CKTR]} value
+ * pairs via a board defined ddr_scan_option() function.
+ */
+struct sdram_timing full_scan_options[] = {
+	{0, 0}, {0, 1}, {0, 2}, {0, 3},
+	{1, 0}, {1, 1}, {1, 2}, {1, 3},
+	{2, 0}, {2, 1}, {2, 2}, {2, 3},
+	{3, 0}, {3, 1}, {3, 2}, {3, 3},
+	{4, 0}, {4, 1}, {4, 2}, {4, 3},
+	{5, 0}, {5, 1}, {5, 2}, {5, 3},
+	{6, 0}, {6, 1}, {6, 2}, {6, 3},
+	{-1, -1}
+};
+
+/*---------------------------------------------------------------------------+
+| DQS_calibration.
++----------------------------------------------------------------------------*/
+u32 DQS_autocalibration(void)
+{
+	u32 wdtr;
+	u32 clkp;
+	u32 result = 0;
+	u32 best_result = 0;
+	u32 best_rdcc;
+	struct ddrautocal ddrcal;
+	struct autocal_clks tcal;
+	ulong rfdc_reg;
+	ulong rqdc_reg;
+	u32 val;
+	int verbose_lvl = 0;
+	char *str;
+	char slash[] = "\\|/-\\|/-";
+	int loopi = 0;
+	struct sdram_timing *scan_list;
+
+#if defined(DEBUG_PPC4xx_DDR_AUTOCALIBRATION)
+	int i;
+	char tmp[64];	/* long enough for environment variables */
+#endif
+
+	memset(&tcal, 0, sizeof(tcal));
+
+	ddr_scan_option((ulong)full_scan_options);
+
+	scan_list =
+	      (struct sdram_timing *)ddr_scan_option((ulong)full_scan_options);
+
+	mfsdram(SDRAM_MCOPT1, val);
+	if ((val & SDRAM_MCOPT1_MCHK_CHK_REP) == SDRAM_MCOPT1_MCHK_CHK_REP)
+		str = "ECC Auto calibration -";
+	else
+		str = "Auto calibration -";
+
+	puts(str);
+
+#if defined(DEBUG_PPC4xx_DDR_AUTOCALIBRATION)
+	i = getenv_r("autocalib", tmp, sizeof(tmp));
+	if (i < 0)
+		strcpy(tmp, CONFIG_AUTOCALIB);
+
+	if (strcmp(tmp, "final") == 0) {
+		/* display the final autocalibration results only */
+		verbose_lvl = 1;
+	} else if (strcmp(tmp, "loop") == 0) {
+		/* display summary autocalibration info per iteration */
+		verbose_lvl = 2;
+	} else if (strcmp(tmp, "display") == 0) {
+		/* display full debug autocalibration window info. */
+		verbose_lvl = 3;
+	}
+#endif /* (DEBUG_PPC4xx_DDR_AUTOCALIBRATION) */
+
+	best_rdcc = (SDRAM_RDCC_RDSS_T4 >> 30);
+
+	while ((scan_list->wrdtr != -1) && (scan_list->clktr != -1)) {
+		wdtr = scan_list->wrdtr;
+		clkp = scan_list->clktr;
+
+		mfsdram(SDRAM_WRDTR, val);
+		val &= ~(SDRAM_WRDTR_LLWP_MASK | SDRAM_WRDTR_WTR_MASK);
+		mtsdram(SDRAM_WRDTR, (val |
+			ddr_wrdtr(SDRAM_WRDTR_LLWP_1_CYC | (wdtr << 25))));
+
+		mtsdram(SDRAM_CLKTR, clkp << 30);
+
+		putc('\b');
+		putc(slash[loopi++ % 8]);
+
+#ifdef DEBUG
+		debug("\n");
+		debug("*** --------------\n");
+		mfsdram(SDRAM_WRDTR, val);
+		debug("*** SDRAM_WRDTR set to 0x%08x\n", val);
+		mfsdram(SDRAM_CLKTR, val);
+		debug("*** SDRAM_CLKTR set to 0x%08x\n", val);
+#endif
+
+		debug("\n");
+		if (verbose_lvl > 2) {
+			printf("*** SDRAM_WRDTR (wdtr) set to %d\n", wdtr);
+			printf("*** SDRAM_CLKTR (clkp) set to %d\n", clkp);
+		}
+
+		memset(&ddrcal, 0, sizeof(ddrcal));
+
+		/*
+		 * DQS calibration.
+		 */
+		/*
+		 * program_DQS_calibration_method[A|B]() returns 0 if no
+		 * passing RFDC.[RFFD] window is found or returns the size
+		 * of the best passing window; in the case of a found passing
+		 * window, the ddrcal will contain the values of the best
+		 * window RQDC.[RQFD] and RFDC.[RFFD].
+		 */
+
+		/*
+		 * Call PPC4xx SDRAM DDR autocalibration methodA or methodB.
+		 * Default is methodB.
+		 * Defined the autocalibration method in the board specific
+		 * header file.
+		 * Please see include/configs/kilauea.h for an example for
+		 * a board specific implementation.
+		 */
+#if defined(CONFIG_PPC4xx_DDR_METHOD_A)
+		result = program_DQS_calibration_methodA(&ddrcal);
+#else
+		result = program_DQS_calibration_methodB(&ddrcal);
+#endif
+
+		sync();
+
+		/*
+		 * Clear potential errors resulting from auto-calibration.
+		 * If not done, then we could get an interrupt later on when
+		 * exceptions are enabled.
+		 */
+		set_mcsr(get_mcsr());
+
+		val = ddrcal.rdcc;	/* RDCC from the best passing window */
+
+		udelay(100);
+
+		if (verbose_lvl > 1) {
+			char *tstr;
+			switch ((val >> 30)) {
+			case 0:
+				if (result != 0)
+					tstr = "T1";
+				else
+					tstr = "N/A";
+				break;
+			case 1:
+				tstr = "T2";
+				break;
+			case 2:
+				tstr = "T3";
+				break;
+			case 3:
+				tstr = "T4";
+				break;
+			default:
+				tstr = "unknown";
+				break;
+			}
+			printf("** WRDTR(%d) CLKTR(%d), Wind (%d), best (%d), "
+			       "max-min(0x%04x)(0x%04x), RDCC: %s\n",
+				wdtr, clkp, result, best_result,
+				ddrcal.rffd_min, ddrcal.rffd_max, tstr);
+		}
+
+		/*
+		 * The DQS calibration "result" is either "0"
+		 * if no passing window was found, or is the
+		 * size of the RFFD passing window.
+		 */
+		if (result != 0) {
+			tcal.autocal.flags = 1;
+			debug("*** (%d)(%d) result passed window size: 0x%08x, "
+			      "rqfd = 0x%08x, rffd = 0x%08x, rdcc = 0x%08x\n",
+				wdtr, clkp, result, ddrcal.rqfd,
+				ddrcal.rffd, ddrcal.rdcc);
+			/*
+			 * Save the SDRAM_WRDTR and SDRAM_CLKTR
+			 * settings for the largest returned
+			 * RFFD passing window size.
+			 */
+			if (result > best_result) {
+				/*
+				 * want the lowest Read Sample Cycle Select
+				 */
+				val = (val & SDRAM_RDCC_RDSS_MASK) >> 30;
+				debug("*** (%d) (%d) current_rdcc, best_rdcc\n",
+							val, best_rdcc);
+				if (val <= best_rdcc) {
+					best_rdcc = val;
+					tcal.clocks.wrdtr = wdtr;
+					tcal.clocks.clktr = clkp;
+					tcal.clocks.rdcc = (val << 30);
+					tcal.autocal.rqfd = ddrcal.rqfd;
+					tcal.autocal.rffd = ddrcal.rffd;
+					best_result = result;
+
+					if (verbose_lvl > 2) {
+						printf("** (%d)(%d)  "
+						       "best result: 0x%04x\n",
+							wdtr, clkp,
+							best_result);
+						printf("** (%d)(%d)  "
+						       "best WRDTR: 0x%04x\n",
+							wdtr, clkp,
+							tcal.clocks.wrdtr);
+						printf("** (%d)(%d)  "
+						       "best CLKTR: 0x%04x\n",
+							wdtr, clkp,
+							tcal.clocks.clktr);
+						printf("** (%d)(%d)  "
+						       "best RQDC: 0x%04x\n",
+							wdtr, clkp,
+							tcal.autocal.rqfd);
+						printf("** (%d)(%d)  "
+						       "best RFDC: 0x%04x\n",
+							wdtr, clkp,
+							tcal.autocal.rffd);
+						printf("** (%d)(%d)  "
+						       "best RDCC: 0x%08x\n",
+							wdtr, clkp,
+							(u32)tcal.clocks.rdcc);
+						mfsdram(SDRAM_RTSR, val);
+						printf("** (%d)(%d)  best "
+						       "loop RTSR: 0x%08x\n",
+							wdtr, clkp, val);
+						mfsdram(SDRAM_FCSR, val);
+						printf("** (%d)(%d)  best "
+						       "loop FCSR: 0x%08x\n",
+							wdtr, clkp, val);
+					}
+				} /* if (val <= best_rdcc) */
+			} /* if (result >= best_result) */
+		} /* if (result != 0) */
+		scan_list++;
+	} /* while ((scan_list->wrdtr != -1) && (scan_list->clktr != -1)) */
+
+	if (tcal.autocal.flags == 1) {
+		if (verbose_lvl > 0) {
+			printf("*** --------------\n");
+			printf("*** best_result window size: %d\n",
+							best_result);
+			printf("*** best_result WRDTR: 0x%04x\n",
+							tcal.clocks.wrdtr);
+			printf("*** best_result CLKTR: 0x%04x\n",
+							tcal.clocks.clktr);
+			printf("*** best_result RQFD: 0x%04x\n",
+							tcal.autocal.rqfd);
+			printf("*** best_result RFFD: 0x%04x\n",
+							tcal.autocal.rffd);
+			printf("*** best_result RDCC: 0x%04x\n",
+							tcal.clocks.rdcc);
+			printf("*** --------------\n");
+			printf("\n");
+		}
+
+		/*
+		 * if got best passing result window, then lock in the
+		 * best CLKTR, WRDTR, RQFD, and RFFD values
+		 */
+		mfsdram(SDRAM_WRDTR, val);
+		mtsdram(SDRAM_WRDTR, (val &
+		    ~(SDRAM_WRDTR_LLWP_MASK | SDRAM_WRDTR_WTR_MASK)) |
+		    ddr_wrdtr(SDRAM_WRDTR_LLWP_1_CYC |
+					(tcal.clocks.wrdtr << 25)));
+
+		mtsdram(SDRAM_CLKTR, tcal.clocks.clktr << 30);
+
+		mfsdram(SDRAM_RQDC, rqdc_reg);
+		rqdc_reg &= ~(SDRAM_RQDC_RQFD_MASK);
+		mtsdram(SDRAM_RQDC, rqdc_reg |
+				SDRAM_RQDC_RQFD_ENCODE(tcal.autocal.rqfd));
+
+		mfsdram(SDRAM_RQDC, rqdc_reg);
+		debug("*** best_result: read value SDRAM_RQDC 0x%08x\n",
+				rqdc_reg);
+
+		mfsdram(SDRAM_RFDC, rfdc_reg);
+		rfdc_reg &= ~(SDRAM_RFDC_RFFD_MASK);
+		mtsdram(SDRAM_RFDC, rfdc_reg |
+				SDRAM_RFDC_RFFD_ENCODE(tcal.autocal.rffd));
+
+		mfsdram(SDRAM_RFDC, rfdc_reg);
+		debug("*** best_result: read value SDRAM_RFDC 0x%08x\n",
+				rfdc_reg);
+		mfsdram(SDRAM_RDCC, val);
+		debug("***  SDRAM_RDCC 0x%08x\n", val);
+	} else {
+		/*
+		 * no valid windows were found
+		 */
+		printf("DQS memory calibration window can not be determined, "
+		       "terminating u-boot.\n");
+		ppc4xx_ibm_ddr2_register_dump();
+		spd_ddr_init_hang();
+	}
+
+	blank_string(strlen(str));
+
+	return 0;
+}
+#else /* defined(CONFIG_NAND_U_BOOT) || defined(CONFIG_NAND_SPL) */
+u32 DQS_autocalibration(void)
+{
+	return 0;
+}
+#endif /* !defined(CONFIG_NAND_U_BOOT) && !defined(CONFIG_NAND_SPL) */
+#endif /* defined(CONFIG_PPC4xx_DDR_AUTOCALIBRATION) */