[U-Boot] [PATCH v2 2/3] ddr: vybrid: Provide code to perform on-boot calibration

Lukasz Majewski
2018-12-05T16:04:02Z

This patch provides the code to calibrate the DDR's
DQS to DQ signals (RDLVL).

It is based on:
VFxxx Controller Reference Manual, Rev. 0, 10/2016, page 1600
10.1.6.16.4.1 "Software Read Leveling in MC Evaluation Mode"

and NXP's community thread:
"Vybrid: About DDR leveling feature on DDRMC."
https://community.nxp.com/thread/395323

Signed-off-by: Lukasz Majewski <lukma@denx.de>

---

Changes in v2:
- CR93_SWLVL_EXIT -> CR94_SWLVL_EXIT (EXIT is in CR94)
- Update Kconfig information regarding DDRMC_VF610_CALIBRATION
- Update ddrmc-vf610-calibration. comment
- Update code after extending imx-regs.h

arch/arm/mach-imx/Kconfig | 12 +
arch/arm/mach-imx/Makefile | 1 +
arch/arm/mach-imx/ddrmc-vf610-calibration.c | 342 ++++++++++++++++++++++++++++
arch/arm/mach-imx/ddrmc-vf610-calibration.h | 45 ++++
4 files changed, 400 insertions(+)
create mode 100644 arch/arm/mach-imx/ddrmc-vf610-calibration.c
create mode 100644 arch/arm/mach-imx/ddrmc-vf610-calibration.h

diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index a1566cc2ad..8631fbd481 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -78,3 +78,15 @@ config NXP_BOARD_REVISION
NXP boards based on i.MX6/7 contain the board revision information
stored in the fuses. Select this option if you want to be able to
retrieve the board revision information.
+
+config DDRMC_VF610_CALIBRATION
+ bool "Enable DDRMC (DDR3) on-chip calibration"
+ depends on ARCH_VF610
+ help
+ Vybrid (vf610) SoC provides some on-chip facility to tune the DDR3
+ memory parameters. Select this option if you want to calculate them
+ at boot time.
+ NOTE:
+ NXP does NOT recommend to perform this calibration at each boot. One
+ shall perform it on a new PCB and then use those values to program
+ the ddrmc_cr_setting on relevant board file.
diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index 53d9e5f42b..4a07b1ea69 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_SECURE_BOOT) += hab.o
endif
ifeq ($(SOC),$(filter $(SOC),vf610))
obj-y += ddrmc-vf610.o
+obj-$(CONFIG_DDRMC_VF610_CALIBRATION) += ddrmc-vf610-calibration.o
endif
ifneq ($(CONFIG_SPL_BUILD),y)
obj-$(CONFIG_CMD_BMODE) += cmd_bmode.o
diff --git a/arch/arm/mach-imx/ddrmc-vf610-calibration.c b/arch/arm/mach-imx/ddrmc-vf610-calibration.c
new file mode 100644
index 0000000000..f29de74c39
--- /dev/null
+++ b/arch/arm/mach-imx/ddrmc-vf610-calibration.c
@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * ddrmc DDR3 calibration code for NXP's VF610
+ *
+ * Copyright (C) 2018 DENX Software Engineering
+ * Lukasz Majewski, DENX Software Engineering, lukma at denx.de
+ *
+ */
+/* #define DEBUG */
+#include <common.h>
+#include <asm/io.h>
+#include <asm/arch/imx-regs.h>
+#include <linux/bitmap.h>
+
+#include "ddrmc-vf610-calibration.h"
+
+/*
+ * Documents:
+ *
+ * [1] "Vybrid: About DDR leveling feature on DDRMC."
+ * https://community.nxp.com/thread/395323
+ *
+ * [2] VFxxx Controller Reference Manual, Rev. 0, 10/2016
+ *
+ *
+ * NOTE
+ * ====
+ *
+ * NXP recommends setting 'fixed' parameters instead of performing the
+ * training at each boot.
+ *
+ * Use those functions to determine those values on new HW, read the
+ * calculated value from registers and add them to the board specific
+ * struct ddrmc_cr_setting.
+ *
+ * SW leveling supported operations - CR93[SW_LVL_MODE]:
+ *
+ * - 0x0 (b'00) - No leveling
+ *
+ * - 0x1 (b'01) - WRLVL_DL_X - It is not recommended to perform this tuning
+ * on HW designs utilizing non-flyback topology
+ * (Single DDR3 with x16).
+ * Instead the WRLVL_DL_0/1 fields shall be set
+ * based on trace length differences from their
+ * layout.
+ * Mismatches up to 25% or tCK (clock period) are
+ * allowed, so the value in the filed doesn’t have
+ * to be very accurate.
+ *
+ * - 0x2 (b'10) - RDLVL_DL_0/1 - refers to adjusting the DQS strobe in relation
+ * to the DQ signals so that the strobe edge is
+ * centered in the window of valid read data.
+ *
+ * - 0x3 (b'11) - RDLVL_GTDL_0/1 - refers to the delay the PHY uses to un-gate
+ * the Read DQS strobe pad from the time that the
+ * PHY enables the pad to input the strobe signal.
+ *
+ */
+static int ddr_cal_get_first_edge_index(unsigned long *bmap, enum edge e,
+ int samples, int start, int max)
+{
+ int i, ret = -1;
+
+ /*
+ * We look only for the first value (and filter out
+ * some wrong data)
+ */
+ switch (e) {
+ case RISING_EDGE:
+ for (i = start; i <= max - samples; i++) {
+ if (test_bit(i, bmap)) {
+ if (!test_bit(i - 1, bmap) &&
+ test_bit(i + 1, bmap) &&
+ test_bit(i + 2, bmap) &&
+ test_bit(i + 3, bmap)) {
+ return i;
+ }
+ }
+ }
+ break;
+ case FALLING_EDGE:
+ for (i = start; i <= max - samples; i++) {
+ if (!test_bit(i, bmap)) {
+ if (test_bit(i - 1, bmap) &&
+ test_bit(i - 2, bmap) &&
+ test_bit(i - 3, bmap)) {
+ return i;
+ }
+ }
+ }
+ }
+
+ return ret;
+}
+
+static void bitmap_print(unsigned long *bmap, int max)
+{
+ int i;
+
+ debug("BITMAP [0x%p]:\n", bmap);
+ for (i = 0; i <= max; i++) {
+ debug("%d ", test_bit(i, bmap) ? 1 : 0);
+ if (i && (i % 32) == (32 - 1))
+ debug("\n");
+ }
+ debug("\n");
+}
+
+#define sw_leveling_op_done \
+ while (!(readl(&ddrmr->cr[94]) & DDRMC_CR94_SWLVL_OP_DONE))
+
+#define sw_leveling_load_value \
+ do { clrsetbits_le32(&ddrmr->cr[93], DDRMC_CR93_SWLVL_LOAD, \
+ DDRMC_CR93_SWLVL_LOAD); } while (0)
+
+#define sw_leveling_start \
+ do { clrsetbits_le32(&ddrmr->cr[93], DDRMC_CR93_SWLVL_START, \
+ DDRMC_CR93_SWLVL_START); } while (0)
+
+#define sw_leveling_exit \
+ do { clrsetbits_le32(&ddrmr->cr[94], DDRMC_CR94_SWLVL_EXIT, \
+ DDRMC_CR94_SWLVL_EXIT); } while (0)
+
+/*
+ * RDLVL_DL calibration:
+ *
+ * NXP is _NOT_ recommending performing the leveling at each
+ * boot. Instead - one shall run this procedure on new boards
+ * and then use hardcoded values.
+ *
+ */
+static int ddrmc_cal_dqs_to_dq(struct ddrmr_regs *ddrmr)
+{
+ DECLARE_BITMAP(rdlvl_rsp, DDRMC_DQS_DQ_MAX_DELAY + 1);
+ int rdlvl_dl_0_min = -1, rdlvl_dl_0_max = -1;
+ int rdlvl_dl_1_min = -1, rdlvl_dl_1_max = -1;
+ int rdlvl_dl_0, rdlvl_dl_1;
+ u8 swlvl_rsp;
+ u32 tmp;
+ int i;
+
+ /* Read defaults */
+ u16 rdlvl_dl_0_def =
+ (readl(&ddrmr->cr[105]) >> DDRMC_CR105_RDLVL_DL_0_OFF) & 0xFFFF;
+ u16 rdlvl_dl_1_def = readl(&ddrmr->cr[110]) & 0xFFFF;
+
+ debug("\nRDLVL: ======================\n");
+ debug("RDLVL: DQS to DQ (RDLVL)\n");
+
+ debug("RDLVL: RDLVL_DL_0_DFL:\t 0x%x\n", rdlvl_dl_0_def);
+ debug("RDLVL: RDLVL_DL_1_DFL:\t 0x%x\n", rdlvl_dl_1_def);
+
+ /*
+ * Set/Read setup for calibration
+ *
+ * Values necessary for leveling from Vybrid RM [2] - page 1600
+ */
+ writel(0x40703030, &ddrmr->cr[144]);
+ writel(0x40, &ddrmr->cr[145]);
+ writel(0x40, &ddrmr->cr[146]);
+
+ tmp = readl(&ddrmr->cr[144]);
+ debug("RDLVL: PHY_RDLVL_RES:\t 0x%x\n", (tmp >> 24) & 0xFF);// set 0x40
+ debug("RDLVL: PHY_RDLV_LOAD:\t 0x%x\n", (tmp >> 16) & 0xFF);// set 0x70
+ debug("RDLVL: PHY_RDLV_DLL:\t 0x%x\n", (tmp >> 8) & 0xFF); // set 0x30
+ debug("RDLVL: PHY_RDLV_EN:\t 0x%x\n", tmp & 0xFF); //set 0x30
+
+ tmp = readl(&ddrmr->cr[145]);
+ debug("RDLVL: PHY_RDLV_RR:\t 0x%x\n", tmp & 0x3FF); //set 0x40
+
+ tmp = readl(&ddrmr->cr[146]);
+ debug("RDLVL: PHY_RDLV_RESP:\t 0x%x\n", tmp); //set 0x40
+
+ /*
+ * Program/read the leveling edge RDLVL_EDGE = 0
+ *
+ * 0x00 is the correct output on SWLVL_RSP_X
+ * If by any chance 1s are visible -> wrong number read
+ */
+ clrbits_le32(&ddrmr->cr[101], DDRMC_CR101_PHY_RDLVL_EDGE);
+
+ tmp = readl(&ddrmr->cr[101]);
+ debug("RDLVL: PHY_RDLVL_EDGE:\t 0x%x\n",
+ (tmp >> DDRMC_CR101_PHY_RDLVL_EDGE_OFF) & 0x1); //set 0
+
+ /* Program Leveling mode - CR93[SW_LVL_MODE] to ’b10 */
+ clrsetbits_le32(&ddrmr->cr[93], DDRMC_CR93_SW_LVL_MODE(0x3),
+ DDRMC_CR93_SW_LVL_MODE(0x2));
+ tmp = readl(&ddrmr->cr[93]);
+ debug("RDLVL: SW_LVL_MODE:\t 0x%x\n",
+ (tmp >> DDRMC_CR93_SW_LVL_MODE_OFF) & 0x3);
+
+ /* Start procedure - CR93[SWLVL_START] to ’b1 */
+ sw_leveling_start;
+
+ /* Poll CR94[SWLVL_OP_DONE] */
+ sw_leveling_op_done;
+
+ /*
+ * Program delays for RDLVL_DL_0
+ *
+ * The procedure is to increase the delay values from 0 to 0xFF
+ * and read the response from the DDRMC
+ */
+ debug("\nRDLVL: ---> RDLVL_DL_0\n");
+ bitmap_zero(rdlvl_rsp, DDRMC_DQS_DQ_MAX_DELAY + 1);
+
+ for (i = 0; i <= DDRMC_DQS_DQ_MAX_DELAY; i++) {
+ clrsetbits_le32(&ddrmr->cr[105],
+ 0xFFFF << DDRMC_CR105_RDLVL_DL_0_OFF,
+ i << DDRMC_CR105_RDLVL_DL_0_OFF);
+
+ /* Load values CR93[SWLVL_LOAD] to ’b1 */
+ sw_leveling_load_value;
+
+ /* Poll CR94[SWLVL_OP_DONE] */
+ sw_leveling_op_done;
+
+ /*
+ * Read Responses - SWLVL_RESP_0
+ *
+ * The 0x00 (correct response when PHY_RDLVL_EDGE = 0)
+ * -> 1 in the bit vector
+ */
+ swlvl_rsp = (readl(&ddrmr->cr[94]) >>
+ DDRMC_CR94_SWLVL_RESP_0_OFF) & 0xF;
+ if (swlvl_rsp == 0)
+ generic_set_bit(i, rdlvl_rsp);
+ }
+
+ bitmap_print(rdlvl_rsp, DDRMC_DQS_DQ_MAX_DELAY);
+
+ /*
+ * First test for rising edge 0x0 -> 0x1 in bitmap
+ */
+ rdlvl_dl_0_min = ddr_cal_get_first_edge_index(rdlvl_rsp, RISING_EDGE,
+ N_SAMPLES, N_SAMPLES,
+ DDRMC_DQS_DQ_MAX_DELAY);
+
+ /*
+ * Secondly test for falling edge 0x1 -> 0x0 in bitmap
+ */
+ rdlvl_dl_0_max = ddr_cal_get_first_edge_index(rdlvl_rsp, FALLING_EDGE,
+ N_SAMPLES, rdlvl_dl_0_min,
+ DDRMC_DQS_DQ_MAX_DELAY);
+
+ debug("RDLVL: DL_0 min: %d [0x%x] DL_0 max: %d [0x%x]\n",
+ rdlvl_dl_0_min, rdlvl_dl_0_min, rdlvl_dl_0_max, rdlvl_dl_0_max);
+ rdlvl_dl_0 = (rdlvl_dl_0_max - rdlvl_dl_0_min) / 2;
+
+ if (rdlvl_dl_0_max == -1 || rdlvl_dl_0_min == -1 || rdlvl_dl_0 <= 0) {
+ debug("RDLVL: The DQS to DQ delay cannot be found!\n");
+ debug("RDLVL: Using default - slice 0: %d!\n", rdlvl_dl_0_def);
+ rdlvl_dl_0 = rdlvl_dl_0_def;
+ }
+
+ debug("\nRDLVL: ---> RDLVL_DL_1\n");
+ bitmap_zero(rdlvl_rsp, DDRMC_DQS_DQ_MAX_DELAY + 1);
+
+ for (i = 0; i <= DDRMC_DQS_DQ_MAX_DELAY; i++) {
+ clrsetbits_le32(&ddrmr->cr[110],
+ 0xFFFF << DDRMC_CR110_RDLVL_DL_1_OFF,
+ i << DDRMC_CR110_RDLVL_DL_1_OFF);
+
+ /* Load values CR93[SWLVL_LOAD] to ’b1 */
+ sw_leveling_load_value;
+
+ /* Poll CR94[SWLVL_OP_DONE] */
+ sw_leveling_op_done;
+
+ /*
+ * Read Responses - SWLVL_RESP_1
+ *
+ * The 0x00 (correct response when PHY_RDLVL_EDGE = 0)
+ * -> 1 in the bit vector
+ */
+ swlvl_rsp = (readl(&ddrmr->cr[95]) >>
+ DDRMC_CR95_SWLVL_RESP_1_OFF) & 0xF;
+ if (swlvl_rsp == 0)
+ generic_set_bit(i, rdlvl_rsp);
+ }
+
+ bitmap_print(rdlvl_rsp, DDRMC_DQS_DQ_MAX_DELAY);
+
+ /*
+ * First test for rising edge 0x0 -> 0x1 in bitmap
+ */
+ rdlvl_dl_1_min = ddr_cal_get_first_edge_index(rdlvl_rsp, RISING_EDGE,
+ N_SAMPLES, N_SAMPLES,
+ DDRMC_DQS_DQ_MAX_DELAY);
+
+ /*
+ * Secondly test for falling edge 0x1 -> 0x0 in bitmap
+ */
+ rdlvl_dl_1_max = ddr_cal_get_first_edge_index(rdlvl_rsp, FALLING_EDGE,
+ N_SAMPLES, rdlvl_dl_1_min,
+ DDRMC_DQS_DQ_MAX_DELAY);
+
+ debug("RDLVL: DL_1 min: %d [0x%x] DL_1 max: %d [0x%x]\n",
+ rdlvl_dl_1_min, rdlvl_dl_1_min, rdlvl_dl_1_max, rdlvl_dl_1_max);
+ rdlvl_dl_1 = (rdlvl_dl_1_max - rdlvl_dl_1_min) / 2;
+
+ if (rdlvl_dl_1_max == -1 || rdlvl_dl_1_min == -1 || rdlvl_dl_1 <= 0) {
+ debug("RDLVL: The DQS to DQ delay cannot be found!\n");
+ debug("RDLVL: Using default - slice 1: %d!\n", rdlvl_dl_1_def);
+ rdlvl_dl_1 = rdlvl_dl_1_def;
+ }
+
+ debug("RDLVL: CALIBRATED: rdlvl_dl_0: 0x%x\t rdlvl_dl_1: 0x%x\n",
+ rdlvl_dl_0, rdlvl_dl_1);
+
+ /* Write new delay values */
+ writel(DDRMC_CR105_RDLVL_DL_0(rdlvl_dl_0), &ddrmr->cr[105]);
+ writel(DDRMC_CR110_RDLVL_DL_1(rdlvl_dl_1), &ddrmr->cr[110]);
+
+ sw_leveling_load_value;
+ sw_leveling_op_done;
+
+ /* Exit procedure - CR94[SWLVL_EXIT] to ’b1 */
+ sw_leveling_exit;
+
+ /* Poll CR94[SWLVL_OP_DONE] */
+ sw_leveling_op_done;
+
+ return 0;
+}
+
+/*
+ * WRLVL_DL calibration:
+ *
+ * For non-flyback memory architecture - where one have a single DDR3 x16
+ * memory - it is NOT necessary to perform "Write Leveling"
+ * [3] 'Vybrid DDR3 write leveling' https://community.nxp.com/thread/429362
+ *
+ */
+
+int ddrmc_calibration(struct ddrmr_regs *ddrmr)
+{
+ ddrmc_cal_dqs_to_dq(ddrmr);
+
+ return 0;
+}
diff --git a/arch/arm/mach-imx/ddrmc-vf610-calibration.h b/arch/arm/mach-imx/ddrmc-vf610-calibration.h
new file mode 100644
index 0000000000..e82e217ab3
--- /dev/null
+++ b/arch/arm/mach-imx/ddrmc-vf610-calibration.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * ddrmc DDR3 calibration code for NXP's VF610
+ *
+ * Copyright (C) 2018 DENX Software Engineering
+ * Lukasz Majewski, DENX Software Engineering, lukma at denx.de
+ *
+ */
+
+#ifndef __DDRMC_VF610_CALIBRATOIN_H_
+#define __DDRMC_VF610_CALIBRATOIN_H_
+
+/*
+ * Number of "samples" in the calibration bitmap
+ * to be considered during calibration.
+ */
+#define N_SAMPLES 3
+
+/*
+ * Constants to indicate if we are looking for a rising or
+ * falling edge in the calibration bitmap
+ */
+enum edge {
+ FALLING_EDGE = 1,
+ RISING_EDGE
+};
+
+/*
+ * The max number of delay elements when DQS to DQ setting
+ */
+#define DDRMC_DQS_DQ_MAX_DELAY 0xFF
+
+/**
+ * ddrmc_calibration - Vybrid's (VF610) DDR3 calibration code
+ *
+ * This function is calculating proper memory controller values
+ * during run time.
+ *
+ * @param ddrmr_regs - memory controller registers
+ *
+ * @return 0 on success, otherwise error code
+ */
+int ddrmc_calibration(struct ddrmr_regs *ddrmr);
+
+#endif /* __DDRMC_VF610_CALIBRATOIN_H_ */
--
2.11.0