From: YannickV <Y.Vossen@beckhoff.com>

The registers for the digitally controlled impedance (DCI) clock are
part of the system level control registers (SLCR). The DONE bit in
the status register indicates a successfull DCI calibration. An
description of the calibration process can be found here:
https://docs.amd.com/r/en-US/ug585-zynq-7000-SoC-TRM/DDR-IOB-Impedance-Calibration

The DCI control register and status register have been added. As soon
as the ENABLE and RESET bit are set, the RESET bit has also been toggled
to 0 before and the UPDATE_CONTROL is not set, the DONE bit in the status
register is set. If these bits change the DONE bit is reset. Note that the
option bits are not taken into consideration.

Signed-off-by: YannickV <Y.Vossen@beckhoff.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
---
 hw/misc/zynq_slcr.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/hw/misc/zynq_slcr.c b/hw/misc/zynq_slcr.c
index 010387beec..d8702da4ce 100644
--- a/hw/misc/zynq_slcr.c
+++ b/hw/misc/zynq_slcr.c
@@ -180,6 +180,12 @@ REG32(GPIOB_CFG_HSTL, 0xb14)
 REG32(GPIOB_DRVR_BIAS_CTRL, 0xb18)
 
 REG32(DDRIOB, 0xb40)
+REG32(DDRIOB_DCI_CTRL, 0xb70)
+    FIELD(DDRIOB_DCI_CTRL, RESET, 0, 1)
+    FIELD(DDRIOB_DCI_CTRL, ENABLE, 1, 1)
+    FIELD(DDRIOB_DCI_CTRL, UPDATE_CONTROL, 20, 1)
+REG32(DDRIOB_DCI_STATUS, 0xb74)
+    FIELD(DDRIOB_DCI_STATUS, DONE, 13, 1)
 #define DDRIOB_LENGTH 14
 
 #define ZYNQ_SLCR_MMIO_SIZE     0x1000
@@ -193,6 +199,8 @@ struct ZynqSLCRState {
 
     MemoryRegion iomem;
 
+    bool ddriob_dci_ctrl_reset_toggled;
+
     uint32_t regs[ZYNQ_SLCR_NUM_REGS];
 
     Clock *ps_clk;
@@ -331,6 +339,8 @@ static void zynq_slcr_reset_init(Object *obj, ResetType type)
 
     DB_PRINT("RESET\n");
 
+    s->ddriob_dci_ctrl_reset_toggled = false;
+
     s->regs[R_LOCKSTA] = 1;
     /* 0x100 - 0x11C */
     s->regs[R_ARM_PLL_CTRL]   = 0x0001A008;
@@ -418,6 +428,8 @@ static void zynq_slcr_reset_init(Object *obj, ResetType type)
     s->regs[R_DDRIOB + 4] = s->regs[R_DDRIOB + 5] = s->regs[R_DDRIOB + 6]
                           = 0x00000e00;
     s->regs[R_DDRIOB + 12] = 0x00000021;
+
+    s->regs[R_DDRIOB_DCI_CTRL] = 0x00000020;
 }
 
 static void zynq_slcr_reset_hold(Object *obj, ResetType type)
@@ -554,6 +566,25 @@ static void zynq_slcr_write(void *opaque, hwaddr offset,
                 (int)offset, (unsigned)val & 0xFFFF);
         }
         return;
+
+    case R_DDRIOB_DCI_CTRL:
+        if (!FIELD_EX32(val, DDRIOB_DCI_CTRL, RESET) &&
+            FIELD_EX32(s->regs[R_DDRIOB_DCI_CTRL], DDRIOB_DCI_CTRL, RESET)) {
+
+            s->ddriob_dci_ctrl_reset_toggled = true;
+            DB_PRINT("DDRIOB DCI CTRL RESET was toggled\n");
+        }
+
+        if (FIELD_EX32(val, DDRIOB_DCI_CTRL, ENABLE) &&
+            FIELD_EX32(val, DDRIOB_DCI_CTRL, RESET) &&
+            !FIELD_EX32(val, DDRIOB_DCI_CTRL, UPDATE_CONTROL) &&
+            s->ddriob_dci_ctrl_reset_toggled) {
+
+            s->regs[R_DDRIOB_DCI_STATUS] |= R_DDRIOB_DCI_STATUS_DONE_MASK;
+        } else {
+            s->regs[R_DDRIOB_DCI_STATUS] &= ~R_DDRIOB_DCI_STATUS_DONE_MASK;
+        }
+        break;
     }
 
     if (s->regs[R_LOCKSTA]) {
-- 
2.47.3