diff --git a/zynq7000/src/slcr.rs b/zynq7000/src/slcr.rs
index 265018b..ed309e1 100644
--- a/zynq7000/src/slcr.rs
+++ b/zynq7000/src/slcr.rs
@@ -3,6 +3,8 @@
 const SLCR_BASE_ADDR: usize = 0xF8000000;
 const CLOCK_CONTROL_OFFSET: usize = 0x100;
 const RESET_BLOCK_OFFSET: usize = 0x200;
+const GPIOB_OFFSET: usize = 0xB00;
+const DDRIOB_OFFSET: usize = 0xB40;
 
 #[derive(derive_mmio::Mmio)]
 #[repr(C)]
@@ -44,6 +46,14 @@ pub struct ResetControl {
 }
 
 impl ResetControl {
+    /// Create a new handle to this peripheral.
+    ///
+    /// Writing to this register requires unlocking the SLCR registers first.
+    ///
+    /// # Safety
+    ///
+    /// If you create multiple instances of this handle at the same time, you are responsible for
+    /// ensuring that there are no read-modify-write races on any of the registers.
     pub fn new_mmio_fixed() -> MmioResetControl<'static> {
         MmioResetControl {
             ptr: (SLCR_BASE_ADDR + RESET_BLOCK_OFFSET) as *mut ResetControl,
@@ -107,7 +117,15 @@ pub struct ClockControl {
 }
 
 impl ClockControl {
-    pub fn new_mmio_fixed() -> MmioClockControl<'static> {
+    /// Create a new handle to this peripheral.
+    ///
+    /// Writing to this register requires unlocking the SLCR registers first.
+    ///
+    /// # Safety
+    ///
+    /// If you create multiple instances of this handle at the same time, you are responsible for
+    /// ensuring that there are no read-modify-write races on any of the registers.
+    pub unsafe fn new_mmio_fixed() -> MmioClockControl<'static> {
         MmioClockControl {
             ptr: (SLCR_BASE_ADDR + CLOCK_CONTROL_OFFSET) as *mut ClockControl,
             phantom: core::marker::PhantomData,
@@ -124,6 +142,89 @@ impl ClockControl {
 
 static_assertions::const_assert_eq!(core::mem::size_of::<ClockControl>(), 0xC8);
 
+#[derive(derive_mmio::Mmio)]
+#[mmio(no_ctors)]
+#[repr(C)]
+pub struct DdrIoB {
+    ddriob_addr0: u32,
+    ddriob_addr1: u32,
+    ddriob_data0: u32,
+    ddriob_data1: u32,
+    ddriob_diff0: u32,
+    ddriob_diff1: u32,
+    ddriob_clock: u32,
+    ddriob_drive_slew_addr: u32,
+    ddriob_drive_slew_data: u32,
+    ddriob_drive_slew_diff: u32,
+    ddriob_drive_slew_clock: u32,
+    ddriob_ddr_ctrl: u32,
+    ddriob_dci_ctrl: u32,
+    ddriob_dci_status: u32,
+}
+
+impl DdrIoB {
+    /// Create a new handle to this peripheral.
+    ///
+    /// Writing to this register requires unlocking the SLCR registers first.
+    ///
+    /// # Safety
+    ///
+    /// If you create multiple instances of this handle at the same time, you are responsible for
+    /// ensuring that there are no read-modify-write races on any of the registers.
+    pub fn new_mmio_fixed() -> MmioDdrIoB<'static> {
+        MmioDdrIoB {
+            ptr: (SLCR_BASE_ADDR + DDRIOB_OFFSET) as *mut _,
+            phantom: core::marker::PhantomData,
+        }
+    }
+
+    fn new_mmio(reg: *mut DdrIoB) -> MmioDdrIoB<'static> {
+        MmioDdrIoB {
+            ptr: reg,
+            phantom: core::marker::PhantomData,
+        }
+    }
+}
+
+static_assertions::const_assert_eq!(core::mem::size_of::<DdrIoB>(), 0x38);
+
+#[derive(derive_mmio::Mmio)]
+#[mmio(no_ctors)]
+#[repr(C)]
+pub struct GpiobCtrl {
+    ctrl: u32,
+    cfg_cmos18: u32,
+    cfg_cmos25: u32,
+    cfg_cmos33: u32,
+    _gap17: u32,
+    cfg_hstl: u32,
+    drvr_bias_ctrl: u32,
+}
+
+impl GpiobCtrl {
+    /// Create a new handle to this peripheral.
+    ///
+    /// Writing to this register requires unlocking the SLCR registers first.
+    ///
+    /// # Safety
+    ///
+    /// If you create multiple instances of this handle at the same time, you are responsible for
+    /// ensuring that there are no read-modify-write races on any of the registers.
+    pub fn new_mmio_fixed() -> MmioGpiobCtrl<'static> {
+        MmioGpiobCtrl {
+            ptr: (SLCR_BASE_ADDR + GPIOB_OFFSET) as *mut _,
+            phantom: core::marker::PhantomData,
+        }
+    }
+
+    fn new_mmio(reg: *mut Self) -> MmioGpiobCtrl<'static> {
+        MmioGpiobCtrl {
+            ptr: reg,
+            phantom: core::marker::PhantomData,
+        }
+    }
+}
+
 #[derive(derive_mmio::Mmio)]
 #[mmio(no_ctors)]
 #[repr(C)]
@@ -178,7 +279,7 @@ pub struct Slcr {
     ddr_urgent_sel: u32,
     ddr_dfi_status: u32,
 
-    _gap9: [u32; 56],
+    _gap9: [u32; 55],
 
     mio_pins: [u32; 54],
 
@@ -188,15 +289,15 @@ pub struct Slcr {
     _gap11: u32,
     mio_mst_tri_0: u32,
     mio_mst_tri_1: u32,
-    _gap12: [u32; 8],
+    _gap12: [u32; 7],
     sd_0_wp_cd_sel: u32,
     sd_1_wp_cd_sel: u32,
 
-    _gap13: [u32; 51],
+    _gap13: [u32; 50],
 
     lvl_shftr_en: u32,
 
-    _gap14: [u32; 4],
+    _gap14: [u32; 3],
 
     ocm_cfg: u32,
 
@@ -206,32 +307,15 @@ pub struct Slcr {
 
     _gap16: [u32; 56],
 
-    gpiob_ctrl: u32,
-    gpiob_cfg_cmos18: u32,
-    gpiob_cfg_cmos25: u32,
-    gpiob_cfg_cmos33: u32,
-    _gap17: u32,
-    gpiob_cfg_hstl: u32,
-    gpiob_drvr_bias_ctrl: u32,
-
     _gap18: [u32; 9],
 
-    ddriob_addr0: u32,
-    ddriob_addr1: u32,
-    ddriob_data0: u32,
-    ddriob_data1: u32,
-    ddriob_diff0: u32,
-    ddriob_diff1: u32,
-    ddriob_clock: u32,
-    ddriob_drive_slew_addr: u32,
-    ddriob_drive_slew_data: u32,
-    ddriob_drive_slew_diff: u32,
-    ddriob_drive_slew_clock: u32,
-    ddriob_ddr_ctrl: u32,
-    ddriob_dci_ctrl: u32,
-    ddriob_dci_status: u32,
+    #[mmio(inner)]
+    gpiob: GpiobCtrl,
+
+    #[mmio(inner)]
+    ddriob: DdrIoB,
 }
 
-//static_assertions::const_assert_eq!(core::mem::size_of::<Slcr>(), 0xB78);
+static_assertions::const_assert_eq!(core::mem::size_of::<Slcr>(), 0xB78);
 
 pub type SystemLevelControlRegisters = Slcr;