diff --git a/Cargo.toml b/Cargo.toml
index aa494d77..b7d0abfd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -42,6 +42,8 @@ yboot-proto = { git = "https://git.alnyan.me/yggdrasil/yboot-proto.git" }
 aml = { git = "https://github.com/alnyan/acpi.git", version = "0.16.4" }
 acpi_lib = { git = "https://github.com/alnyan/acpi.git", version = "4.1.1", package = "acpi" }
 acpi-system = { git = "https://github.com/alnyan/acpi-system.git", version = "0.1.0" }
+# TODO currently only supported here
+xhci_lib = { git = "https://github.com/rust-osdev/xhci.git", package = "xhci" }
 
 [features]
 default = []
diff --git a/src/arch/x86_64/mod.rs b/src/arch/x86_64/mod.rs
index 0b2c7453..bbf042a2 100644
--- a/src/arch/x86_64/mod.rs
+++ b/src/arch/x86_64/mod.rs
@@ -2,7 +2,7 @@
 use core::{ptr::NonNull, sync::atomic::Ordering};
 
 use abi::error::Error;
-use acpi_lib::{AcpiHandler, AcpiTables, HpetInfo, InterruptModel, PhysicalMapping};
+use acpi_lib::{mcfg::Mcfg, AcpiHandler, AcpiTables, HpetInfo, InterruptModel, PhysicalMapping};
 use alloc::boxed::Box;
 use cpu::Cpu;
 use device_api::{
@@ -24,6 +24,7 @@ use crate::{
     debug::{self, LogLevel},
     device::{
         self,
+        bus::pci::PciBusManager,
         display::{console, fb_console::FramebufferConsole, linear_fb::LinearFramebuffer},
         tty::combined::CombinedTerminal,
     },
@@ -392,6 +393,14 @@ impl X86_64 {
         self.timer.init(Hpet::from_acpi(&hpet).unwrap());
 
         acpi::init_acpi(acpi).unwrap();
+
+        // Enumerate PCIe root devices
+        // TODO can there be multiple MCFGs?
+        if let Ok(mcfg) = acpi.find_table::<Mcfg>() {
+            for entry in mcfg.entries() {
+                PciBusManager::add_segment_from_mcfg(entry).unwrap();
+            }
+        }
     }
 
     unsafe fn init_framebuffer(&'static self) {
@@ -469,6 +478,9 @@ impl X86_64 {
             device::register_device(self.timer.get());
             device::register_device(ps2);
 
+            // Initialize devices from PCI bus
+            PciBusManager::setup_bus_devices().unwrap();
+
             infoln!("Device list:");
             for device in device::manager_lock().devices() {
                 infoln!("* {}", device.display_name());
diff --git a/src/arch/x86_64/table/fixed.rs b/src/arch/x86_64/table/fixed.rs
index 0bb7f2a8..ed6cbc7a 100644
--- a/src/arch/x86_64/table/fixed.rs
+++ b/src/arch/x86_64/table/fixed.rs
@@ -72,6 +72,28 @@ impl FixedTables {
             Ok(virt)
         } else {
             // 4KiB mappings
+            // Check if a mapping to that address already exists
+            if self.device_l3i >= count {
+                for i in 0..self.device_l3i {
+                    let mut matches = true;
+
+                    for j in 0..count {
+                        let page = phys + j * 0x1000;
+                        let existing = self.device_l3[i].as_page().unwrap();
+
+                        if page != existing {
+                            matches = false;
+                            break;
+                        }
+                    }
+
+                    if matches {
+                        let virt = DEVICE_VIRT_OFFSET + (i << 12);
+                        return Ok(virt);
+                    }
+                }
+            }
+
             if self.device_l3i + count > 512 {
                 return Err(Error::OutOfMemory);
             }
diff --git a/src/device/bus/mod.rs b/src/device/bus/mod.rs
index 42007f9c..e6810506 100644
--- a/src/device/bus/mod.rs
+++ b/src/device/bus/mod.rs
@@ -2,3 +2,5 @@
 
 #[cfg(feature = "device-tree")]
 pub mod simple_bus;
+
+pub mod pci;
diff --git a/src/device/bus/pci/mod.rs b/src/device/bus/pci/mod.rs
new file mode 100644
index 00000000..3754b413
--- /dev/null
+++ b/src/device/bus/pci/mod.rs
@@ -0,0 +1,238 @@
+use core::fmt;
+
+use acpi_lib::mcfg::McfgEntry;
+use alloc::{rc::Rc, vec::Vec};
+use device_api::Device;
+use yggdrasil_abi::error::Error;
+
+mod space;
+
+pub use space::{
+    ecam::PciEcam, PciConfigSpace, PciConfigurationSpace, PciLegacyConfigurationSpace,
+};
+
+use crate::sync::IrqSafeSpinlock;
+
+pub const PCI_COMMAND_IO: u16 = 1 << 0;
+pub const PCI_COMMAND_MEMORY: u16 = 1 << 1;
+pub const PCI_COMMAND_BUS_MASTER: u16 = 1 << 2;
+pub const PCI_COMMAND_INTERRUPT_DISABLE: u16 = 1 << 10;
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
+pub struct PciAddress {
+    pub segment: u8,
+    pub bus: u8,
+    pub device: u8,
+    pub function: u8,
+}
+
+// TODO other attributes
+#[derive(Debug)]
+pub enum PciBaseAddress {
+    Memory(usize),
+    Io(u16),
+}
+
+#[derive(Debug)]
+pub struct PciDeviceInfo {
+    pub address: PciAddress,
+    pub config_space: PciConfigSpace,
+}
+
+pub trait FromPciBus: Sized {
+    fn from_pci_bus(info: &PciDeviceInfo) -> Result<Self, Error>;
+}
+
+pub struct PciBusDevice {
+    info: PciDeviceInfo,
+    driver: Option<Rc<dyn Device>>,
+}
+
+pub struct PciBusSegment {
+    segment_number: u8,
+    bus_number_start: u8,
+    bus_number_end: u8,
+    ecam_phys_base: Option<usize>,
+
+    devices: Vec<PciBusDevice>,
+}
+
+pub struct PciBusManager {
+    segments: Vec<PciBusSegment>,
+}
+
+impl PciBusSegment {
+    fn probe_config_space(&self, address: PciAddress) -> Result<Option<PciConfigSpace>, Error> {
+        match self.ecam_phys_base {
+            Some(ecam_phys_base) => Ok(unsafe {
+                PciEcam::probe_raw_parts(ecam_phys_base, self.bus_number_start, address)?
+            }
+            .map(PciConfigSpace::Ecam)),
+            None => todo!(),
+        }
+    }
+
+    fn enumerate_function(
+        &mut self,
+        parent: &mut PciBusManager,
+        address: PciAddress,
+    ) -> Result<(), Error> {
+        let Some(config) = self.probe_config_space(address)? else {
+            return Ok(());
+        };
+
+        let header_type = config.header_type();
+
+        // Enumerate multi-function devices
+        if address.function == 0 && header_type & 0x80 != 0 {
+            for function in 1..8 {
+                self.enumerate_function(parent, address.with_function(function))?;
+            }
+        }
+
+        // PCI-to-PCI bridge
+        // if config.class_code() == 0x06 && config.subclass() == 0x04 {
+        //     let secondary_bus = config.secondary_bus();
+        //     // TODO
+        // }
+
+        let info = PciDeviceInfo {
+            address,
+            config_space: config,
+        };
+        self.devices.push(PciBusDevice { info, driver: None });
+
+        Ok(())
+    }
+
+    fn enumerate_bus(&mut self, parent: &mut PciBusManager, bus: u8) -> Result<(), Error> {
+        let address = PciAddress::for_bus(self.segment_number, bus);
+
+        for i in 0..32 {
+            let device_address = address.with_device(i);
+
+            self.enumerate_function(parent, device_address)?;
+        }
+
+        Ok(())
+    }
+
+    pub fn enumerate(&mut self, parent: &mut PciBusManager) -> Result<(), Error> {
+        for bus in self.bus_number_start..self.bus_number_end {
+            self.enumerate_bus(parent, bus)?;
+        }
+        Ok(())
+    }
+}
+
+impl PciBusManager {
+    pub const fn new() -> Self {
+        Self {
+            segments: Vec::new(),
+        }
+    }
+
+    pub fn setup_bus_devices() -> Result<(), Error> {
+        Self::walk_bus_devices(|device| {
+            setup_bus_device(device)?;
+            Ok(true)
+        })
+    }
+
+    pub fn walk_bus_devices<F: FnMut(&mut PciBusDevice) -> Result<bool, Error>>(
+        mut f: F,
+    ) -> Result<(), Error> {
+        let mut this = PCI_MANAGER.lock();
+
+        for segment in this.segments.iter_mut() {
+            for device in segment.devices.iter_mut() {
+                if !f(device)? {
+                    return Ok(());
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn add_segment_from_mcfg(entry: &McfgEntry) -> Result<(), Error> {
+        let mut bus_segment = PciBusSegment {
+            segment_number: entry.pci_segment_group as u8,
+            bus_number_start: entry.bus_number_start,
+            bus_number_end: entry.bus_number_end,
+            ecam_phys_base: Some(entry.base_address as usize),
+
+            devices: Vec::new(),
+        };
+
+        let mut this = PCI_MANAGER.lock();
+        bus_segment.enumerate(&mut *this)?;
+        this.segments.push(bus_segment);
+
+        Ok(())
+    }
+}
+
+impl fmt::Display for PciAddress {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}:{}:{}", self.bus, self.device, self.function)
+    }
+}
+
+impl PciAddress {
+    pub const fn for_bus(segment: u8, bus: u8) -> Self {
+        Self {
+            segment,
+            bus,
+            device: 0,
+            function: 0,
+        }
+    }
+
+    pub const fn with_device(self, device: u8) -> Self {
+        Self {
+            device,
+            function: 0,
+            ..self
+        }
+    }
+
+    pub const fn with_function(self, function: u8) -> Self {
+        Self { function, ..self }
+    }
+}
+
+impl PciConfigurationSpace for PciConfigSpace {
+    fn read_u32(&self, offset: usize) -> u32 {
+        match self {
+            Self::Ecam(ecam) => ecam.read_u32(offset),
+            _ => todo!(),
+        }
+    }
+}
+
+fn setup_bus_device(device: &mut PciBusDevice) -> Result<(), Error> {
+    if device.driver.is_some() {
+        return Ok(());
+    }
+
+    let config = &device.info.config_space;
+
+    debugln!(
+        "{}: {:04x}:{:04x}",
+        device.info.address,
+        config.vendor_id(),
+        config.device_id()
+    );
+
+    // Match by class
+    match (config.class_code(), config.subclass(), config.prog_if()) {
+        _ => {
+            debugln!(" -> No driver");
+        }
+    }
+
+    Ok(())
+}
+
+static PCI_MANAGER: IrqSafeSpinlock<PciBusManager> = IrqSafeSpinlock::new(PciBusManager::new());
diff --git a/src/device/bus/pci/space/ecam.rs b/src/device/bus/pci/space/ecam.rs
new file mode 100644
index 00000000..078e2704
--- /dev/null
+++ b/src/device/bus/pci/space/ecam.rs
@@ -0,0 +1,79 @@
+use yggdrasil_abi::error::Error;
+
+use crate::{
+    device::bus::pci::{PciConfigSpace, PciDeviceInfo},
+    mem::{device::DeviceMemory, ConvertAddress},
+};
+
+use super::{PciAddress, PciConfigurationSpace};
+
+#[derive(Debug)]
+#[repr(transparent)]
+pub struct PciEcam {
+    mapping: DeviceMemory,
+}
+
+// Only used for probing
+#[derive(Debug)]
+#[repr(transparent)]
+struct PciRawEcam {
+    virt_addr: usize,
+}
+
+impl PciConfigurationSpace for PciRawEcam {
+    fn read_u32(&self, offset: usize) -> u32 {
+        assert_eq!(offset & 3, 0);
+        unsafe { ((self.virt_addr + offset) as *const u32).read_volatile() }
+    }
+}
+
+impl PciConfigurationSpace for PciEcam {
+    fn read_u32(&self, offset: usize) -> u32 {
+        assert_eq!(offset & 3, 0);
+        unsafe { ((self.mapping.base() + offset) as *const u32).read_volatile() }
+    }
+}
+
+impl PciEcam {
+    pub unsafe fn map(phys_addr: usize) -> Result<Self, Error> {
+        // TODO check align
+        let mapping = DeviceMemory::map("pcie-ecam", phys_addr, 0x1000)?;
+
+        Ok(PciEcam { mapping })
+    }
+
+    pub unsafe fn from_raw_parts(
+        segment_phys_addr: usize,
+        bus_offset: u8,
+        address: PciAddress,
+    ) -> Result<Self, Error> {
+        todo!()
+    }
+
+    pub unsafe fn probe_raw_parts(
+        segment_phys_addr: usize,
+        bus_offset: u8,
+        address: PciAddress,
+    ) -> Result<Option<Self>, Error> {
+        let phys_addr = segment_phys_addr
+            + ((address.bus - bus_offset) as usize * 256
+                + address.device as usize * 8
+                + address.function as usize)
+                * 0x1000;
+
+        if phys_addr + 0xFFF < 0x100000000 {
+            // Probe without allocating a mapping
+            let raw = PciRawEcam {
+                virt_addr: phys_addr.virtualize(),
+            };
+
+            if !raw.is_valid() {
+                return Ok(None);
+            }
+
+            Self::map(phys_addr).map(Some)
+        } else {
+            todo!()
+        }
+    }
+}
diff --git a/src/device/bus/pci/space/mod.rs b/src/device/bus/pci/space/mod.rs
new file mode 100644
index 00000000..33d2ea27
--- /dev/null
+++ b/src/device/bus/pci/space/mod.rs
@@ -0,0 +1,131 @@
+use super::{PciAddress, PciBaseAddress, PciEcam};
+
+pub(super) mod ecam;
+
+macro_rules! pci_config_field_getter {
+    (u32, $name:ident, $offset:expr) => {
+        fn $name(&self) -> u32 {
+            self.read_u32($offset)
+        }
+    };
+
+    (u16, $name:ident, $offset:expr) => {
+        fn $name(&self) -> u16 {
+            self.read_u16($offset)
+        }
+    };
+
+    (u8, $name:ident, $offset:expr) => {
+        fn $name(&self) -> u8 {
+            self.read_u8($offset)
+        }
+    };
+}
+
+macro_rules! pci_config_field {
+    ($offset:expr => $ty:ident, $getter:ident $(, $setter:ident)?) => {
+        pci_config_field_getter!($ty, $getter, $offset);
+
+        $(
+            fn $setter(&self, value: $ty) {
+                todo!()
+            }
+        )?
+    };
+}
+
+#[derive(Debug)]
+#[repr(transparent)]
+pub struct PciLegacyConfigurationSpace {
+    address: PciAddress,
+}
+
+#[derive(Debug)]
+pub enum PciConfigSpace {
+    Legacy(PciAddress),
+    Ecam(PciEcam),
+}
+
+pub trait PciConfigurationSpace {
+    fn read_u32(&self, offset: usize) -> u32;
+
+    fn read_u16(&self, offset: usize) -> u16 {
+        assert_eq!(offset & 1, 0);
+        let value = self.read_u32(offset & !3);
+        (value >> ((offset & 3) * 8)) as u16
+    }
+
+    fn read_u8(&self, offset: usize) -> u8 {
+        let value = self.read_u32(offset & !3);
+        (value >> ((offset & 3) * 8)) as u8
+    }
+
+    fn is_valid(&self) -> bool {
+        self.vendor_id() != 0xFFFF && self.device_id() != 0xFFFF
+    }
+
+    pci_config_field!(0x00 => u16, vendor_id);
+    pci_config_field!(0x02 => u16, device_id);
+    pci_config_field!(0x04 => u16, command, set_command);
+    pci_config_field!(0x06 => u16, status);
+
+    pci_config_field!(0x08 => u8, rev_id);
+    pci_config_field!(0x09 => u8, prog_if);
+    pci_config_field!(0x0A => u8, subclass);
+    pci_config_field!(0x0B => u8, class_code);
+
+    // ...
+    pci_config_field!(0x0E => u8, header_type);
+    // Header Type 1 only
+    pci_config_field!(0x19 => u8, secondary_bus);
+
+    // Header Type 0 only
+    fn bar(&self, index: usize) -> Option<PciBaseAddress> {
+        assert!(index < 6);
+
+        if index % 2 == 0 {
+            let w0 = self.read_u32(0x10 + index * 4);
+
+            match w0 & 0 {
+                0 => match (w0 >> 1) & 3 {
+                    0 => {
+                        // 32-bit memory BAR
+                        Some(PciBaseAddress::Memory((w0 as usize) & !0xF))
+                    }
+                    2 => {
+                        // 64-bit memory BAR
+                        let w1 = self.read_u32(0x10 + (index + 1) * 4);
+                        Some(PciBaseAddress::Memory(
+                            ((w1 as usize) << 32) | ((w0 as usize) & !0xF),
+                        ))
+                    }
+                    _ => unimplemented!(),
+                },
+                1 => todo!(),
+                _ => unreachable!(),
+            }
+        } else {
+            let prev_w0 = self.read_u32(0x10 + (index - 1) * 4);
+            if prev_w0 & 0x7 == 0x4 {
+                // Previous BAR is 64-bit memory and this one is its continuation
+                return None;
+            }
+
+            let w0 = self.read_u32(0x10 + index * 4);
+
+            match w0 & 0 {
+                0 => match (w0 >> 1) & 3 {
+                    0 => {
+                        // 32-bit memory BAR
+                        Some(PciBaseAddress::Memory((w0 as usize) & !0xF))
+                    }
+                    // TODO can 64-bit BARs not be on a 64-bit boundary?
+                    2 => todo!(),
+                    _ => unimplemented!(),
+                },
+                1 => todo!(),
+                _ => unreachable!(),
+            }
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 63732170..c6a299f7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 //! osdev-x kernel crate
 #![feature(
+    decl_macro,
     naked_functions,
     asm_const,
     panic_info_message,
diff --git a/src/mem/device.rs b/src/mem/device.rs
index f9b9f36b..ca7a2491 100644
--- a/src/mem/device.rs
+++ b/src/mem/device.rs
@@ -6,7 +6,7 @@ use abi::error::Error;
 use crate::arch::{Architecture, ARCHITECTURE};
 
 /// Generic MMIO access mapping
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 #[allow(unused)]
 pub struct DeviceMemory {
     name: &'static str,