Move init implementation into hba and introduce volatile.

rust/lib/mammoth/src/mem.rs

@@ -2,6 +2,8 @@ use crate::cap::Capability;
 use crate::syscall;
 use crate::zion::ZError;
 use alloc::slice;
+use core::fmt::Debug;
+use core::ptr::{addr_of, addr_of_mut};
 
 #[cfg(feature = "hosted")]
 use linked_list_allocator::LockedHeap;
@@ -111,3 +113,42 @@ impl Drop for MemoryRegion {
         syscall::address_space_unmap(self.virt_addr, max).expect("Failed to unmap memory");
     }
 }
+
+pub struct Volatile<T> {
+    /// TODO: This should maybe be MaybeUninit.
+    data: T,
+}
+
+impl<T> Volatile<T> {
+    pub fn read(&self) -> T
+    where
+        T: Copy,
+    {
+        unsafe { addr_of!(self.data).cast::<T>().read_volatile() }
+    }
+
+    pub fn write(&mut self, data: T) {
+        unsafe {
+            addr_of_mut!(self.data).cast::<T>().write_volatile(data);
+        }
+    }
+
+    pub fn update<F>(&mut self, func: F)
+    where
+        T: Copy,
+        F: Fn(&mut T),
+    {
+        let mut data = self.read();
+        func(&mut data);
+        self.write(data);
+    }
+}
+
+impl<T> Debug for Volatile<T>
+where
+    T: Debug + Copy,
+{
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:?}", self.read())
+    }
+}

rust/sys/denali/src/ahci/controller.rs

@@ -76,19 +76,7 @@ impl AhciController {
     }
 
     fn init(&mut self) {
-        self.ahci_hba().global_host_control.set_hba_reset(true);
-
-        mammoth::syscall::thread_sleep(50).unwrap();
-
-        loop {
-            if !self.ahci_hba().global_host_control.hba_reset() {
-                break;
-            }
-        }
-
-        self.ahci_hba().global_host_control.set_ahci_enable(true);
-
-        mammoth::syscall::thread_sleep(50).unwrap();
+        self.ahci_hba().init();
 
         self.init_ports().unwrap();
     }
@@ -107,21 +95,23 @@ impl AhciController {
     }
 
     fn handle_irq(&mut self) {
-        for i in 0..self.ahci_hba().capabilities.num_ports() {
+        for i in 0..self.ahci_hba().capabilities.read().num_ports() {
             let int_offset = 1 << i;
-            if (self.ahci_hba().interrupt_status & int_offset) == int_offset {
+            if (self.ahci_hba().interrupt_status.read() & int_offset) == int_offset {
                 if let Some(port) = &mut self.ports[i as usize] {
                     port.handle_interrupt();
-                    self.ahci_hba().interrupt_status &= !int_offset;
+                    self.ahci_hba().interrupt_status.update(|is| {
+                        *is &= !int_offset;
+                    });
                 }
             }
         }
     }
 
     fn init_ports(&mut self) -> Result<(), ZError> {
-        for i in 0..(self.ahci_hba().capabilities.num_ports() as usize) {
+        for i in 0..(self.ahci_hba().capabilities.read().num_ports() as usize) {
             let port_index = 1 << i;
-            if (self.ahci_hba().port_implemented & port_index) != port_index {
+            if (self.ahci_hba().port_implemented.read() & port_index) != port_index {
                 mammoth::debug!("Skipping port {}, not implemented", i);
                 continue;
             }
@@ -188,7 +178,9 @@ pub fn spawn_irq_thread(controller: Arc<Mutex<AhciController>>) -> thread::JoinH
             .lock()
             .ahci_hba()
             .global_host_control
-            .set_interrupt_enable(true);
+            .update(|ghc| {
+                ghc.set_interrupt_enable(true);
+            });
         loop {
             irq_port.recv_null().unwrap();
             controller.lock().handle_irq();

rust/sys/denali/src/ahci/hba.rs

@@ -1,4 +1,5 @@
 use bitfield_struct::bitfield;
+use mammoth::mem::Volatile;
 
 const fn increment(val: u8) -> u8 {
     val + 1
@@ -144,15 +145,37 @@ pub struct AhciBiosHandoffControl {
 #[derive(Debug)]
 #[repr(C)]
 pub struct AhciHba {
-    pub capabilities: AhciCapabilities,
-    pub global_host_control: AhciGlobalControl,
-    pub interrupt_status: u32,
-    pub port_implemented: u32,
-    pub version: u32,
-    pub ccc_ctl: u32, // 0x14, Command completion coalescing control
-    pub ccc_pts: u32, // 0x18, Command completion coalescing ports
-    pub em_loc: u32,  // 0x1C, Enclosure management location
-    pub em_ctl: u32,  // 0x20, Enclosure management control
-    pub capabilities_ext: AhciCapabilitiesExtended,
-    pub bohc: AhciBiosHandoffControl,
+    pub capabilities: Volatile<AhciCapabilities>,
+    pub global_host_control: Volatile<AhciGlobalControl>,
+    pub interrupt_status: Volatile<u32>,
+    pub port_implemented: Volatile<u32>,
+    pub version: Volatile<u32>,
+    pub ccc_ctl: Volatile<u32>, // 0x14, Command completion coalescing control
+    pub ccc_pts: Volatile<u32>, // 0x18, Command completion coalescing ports
+    pub em_loc: Volatile<u32>,  // 0x1C, Enclosure management location
+    pub em_ctl: Volatile<u32>,  // 0x20, Enclosure management control
+    pub capabilities_ext: Volatile<AhciCapabilitiesExtended>,
+    pub bohc: Volatile<AhciBiosHandoffControl>,
+}
+
+impl AhciHba {
+    pub fn init(&mut self) {
+        self.global_host_control.update(|ghc| {
+            ghc.set_hba_reset(true);
+        });
+
+        mammoth::syscall::thread_sleep(50).unwrap();
+
+        loop {
+            if !self.global_host_control.read().hba_reset() {
+                break;
+            }
+        }
+
+        self.global_host_control.update(|ghc| {
+            ghc.set_ahci_enable(true);
+        });
+
+        mammoth::syscall::thread_sleep(50).unwrap();
+    }
 }