zynq-rs/src/zynq/ddr/mod.rs

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use crate::regs::{RegisterR, RegisterW, RegisterRW};
use super::slcr;
use super::clocks::CpuClocks;
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/// Micron MT41J256M8HX-15E: 667 MHz DDR3
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const DDR_FREQ: u32 = 666_666_666;
const DCI_FREQ: u32 = 10_000_000;
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pub struct DdrRam {
}
impl DdrRam {
pub fn new() -> Self {
let clocks = CpuClocks::get();
Self::clock_setup(&clocks);
Self::calibrate_iob_impedance(&clocks);
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Self::configure_iob();
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let ram = DdrRam {};
ram
}
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/// Zynq-7000 AP SoC Technical Reference Manual:
/// 10.6.1 DDR Clock Initialization
fn clock_setup(clocks: &CpuClocks) {
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let ddr3x_clk_divisor = ((clocks.ddr - 1) / DDR_FREQ + 1).min(255) as u8;
let ddr2x_clk_divisor = 3 * ddr3x_clk_divisor / 2;
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slcr::RegisterBlock::unlocked(|slcr| {
slcr.ddr_pll_ctrl.write(
slcr::PllCtrl::zeroed()
);
slcr.ddr_clk_ctrl.write(
slcr::DdrClkCtrl::zeroed()
.ddr_2xclkact(true)
.ddr_3xclkact(true)
.ddr_2xclk_divisor(ddr2x_clk_divisor)
.ddr_3xclk_divisor(ddr3x_clk_divisor)
);
});
}
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/// Zynq-7000 AP SoC Technical Reference Manual:
/// 10.6.2 DDR IOB Impedance Calibration
fn calibrate_iob_impedance(clocks: &CpuClocks) {
let divisor0 = (clocks.ddr / DCI_FREQ)
.max(1).min(63) as u8;
let divisor1 = (clocks.ddr / DCI_FREQ / u32::from(divisor0))
.max(1).min(63) as u8;
slcr::RegisterBlock::unlocked(|slcr| {
// Step 1.
slcr.dci_clk_ctrl.write(
slcr::DciClkCtrl::zeroed()
.clkact(true)
.divisor0(divisor0)
.divisor1(divisor1)
);
// Step 2.a.
slcr.ddriob_dci_ctrl.modify(|_, w|
w.reset(false)
);
slcr.ddriob_dci_ctrl.modify(|_, w|
w.reset(true)
);
// Step 3.b. for DDR3
slcr.ddriob_dci_ctrl.modify(|_, w|
w.nref_opt1(0)
.nref_opt2(0)
.nref_opt4(1)
.pref_opt1(0)
.pref_opt2(0)
);
// Step 2.c.
slcr.ddriob_dci_ctrl.modify(|_, w|
w.update_control(false)
);
// Step 2.d.
slcr.ddriob_dci_ctrl.modify(|_, w|
w.enable(true)
);
// Step 2.e.
while ! slcr.ddriob_dci_status.read().done() {}
});
}
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/// Zynq-7000 AP SoC Technical Reference Manual:
/// 10.6.3 DDR IOB Configuration
fn configure_iob() {
slcr::RegisterBlock::unlocked(|slcr| {
let addr_config = slcr::DdriobConfig::zeroed()
.output_en(slcr::DdriobOutputEn::Obuf);
slcr.ddriob_addr0.write(addr_config.clone());
slcr.ddriob_addr1.write(addr_config);
let data_config = slcr::DdriobConfig::zeroed()
.inp_type(slcr::DdriobInputType::VrefDifferential)
.term_en(true)
.dci_type(slcr::DdriobDciType::Termination)
.output_en(slcr::DdriobOutputEn::Obuf);
slcr.ddriob_data0.write(data_config.clone());
slcr.ddriob_data1.write(data_config);
let diff_config = slcr::DdriobConfig::zeroed()
.inp_type(slcr::DdriobInputType::Differential)
.term_en(true)
.dci_type(slcr::DdriobDciType::Termination)
.output_en(slcr::DdriobOutputEn::Obuf);
slcr.ddriob_diff0.write(diff_config.clone());
slcr.ddriob_diff1.write(diff_config);
slcr.ddriob_clock.write(
slcr::DdriobConfig::zeroed()
.output_en(slcr::DdriobOutputEn::Obuf)
);
unsafe {
// Not documented in Technical Reference Manual
slcr.ddriob_drive_slew_addr.write(0x0018C61C);
slcr.ddriob_drive_slew_data.write(0x00F9861C);
slcr.ddriob_drive_slew_diff.write(0x00F9861C);
slcr.ddriob_drive_slew_clock.write(0x00F9861C);
}
// Enable internal V[REF]
slcr.ddriob_ddr_ctrl.modify(|_, w| w
.vref_ext_en_lower(false)
.vref_ext_en_upper(false)
.vref_sel(slcr::DdriobVrefSel::Vref0_75V)
.vref_int_en(true)
);
});
}
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}