ddr: vybrid: Provide code to perform on-boot calibration

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>

1 files changed, 45 insertions, 0 deletions

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@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_ */