zynq::ddr: implement reset_ddrc(), add to main

src/main.rs

@@ -94,6 +94,7 @@ fn main() {
              clocks.cpu_3x2x() / 1_000_000,
              clocks.cpu_2x() / 1_000_000,
              clocks.cpu_1x() / 1_000_000);
+    let ddr = zynq::ddr::DdrRam::new();
 
     let eth = zynq::eth::Eth::default(HWADDR.clone());
     println!("Eth on");

src/zynq/ddr/mod.rs

@@ -2,12 +2,13 @@ use crate::regs::{RegisterR, RegisterW, RegisterRW};
 use super::slcr;
 use super::clocks::CpuClocks;
 
+mod regs;
+
 /// Micron MT41J256M8HX-15E: 667 MHz DDR3
 const DDR_FREQ: u32 = 666_666_666;
 const DCI_FREQ: u32 = 10_000_000;
 
-pub struct DdrRam {
-}
+pub struct DdrRam;
 
 impl DdrRam {
     pub fn new() -> Self {
@@ -15,9 +16,9 @@ impl DdrRam {
         Self::clock_setup(&clocks);
         Self::calibrate_iob_impedance(&clocks);
         Self::configure_iob();
+        Self::reset_ddrc();
 
-        let ram = DdrRam {};
-        ram
+        DdrRam
     }
 
     /// Zynq-7000 AP SoC Technical Reference Manual:
@@ -130,4 +131,17 @@ impl DdrRam {
             );
         });
     }
+
+    /// Reset DDR controller
+    fn reset_ddrc() {
+        let regs = unsafe { regs::RegisterBlock::new() };
+        regs.ddrc_ctrl.modify(|_, w| w
+            .soft_rstb(false)
+        );
+        regs.ddrc_ctrl.modify(|_, w| w
+            .soft_rstb(true)
+            .powerdown_en(false)
+            .data_bus_width(regs::DataBusWidth::Width32bit)
+        );
+    }
 }

src/zynq/ddr/regs.rs

@@ -2,9 +2,15 @@ use volatile_register::{RO, WO, RW};
 
 use crate::{register, register_bit, register_bits, register_bits_typed};
 
+#[repr(u8)]
+pub enum DataBusWidth {
+    Width32bit = 0b00,
+    Width16bit = 0b01,
+}
+
 #[repr(C)]
 pub struct RegisterBlock {
-    pub ddrc_ctrl: RW<u32>,
+    pub ddrc_ctrl: DdrcCtrl,
     pub two_rank_cfg: RW<u32>,
     pub hpr_reg: RW<u32>,
     pub lpr_reg: RW<u32>,
@@ -135,3 +141,16 @@ pub struct RegisterBlock {
     pub lpddr_ctrl3: RW<u32>,
 }
 
+impl RegisterBlock {
+    pub unsafe fn new() -> &'static mut Self {
+        &mut *(0xF8006000 as *mut _)
+    }
+}
+
+register!(ddrc_ctrl, DdrcCtrl, RW, u32);
+register_bit!(ddrc_ctrl,
+              /// `false` resets controller, `true` continues
+              soft_rstb, 0);
+register_bit!(ddrc_ctrl, powerdown_en, 1);
+register_bits_typed!(ddrc_ctrl, data_bus_width, u8, DataBusWidth, 2, 3);
+// (ddrc_ctrl) ...