pci - PCI bus scan + driver binding

Header: kernel/include/kernel/pci.h Source: arch/i386/drivers/pci.c

Legacy PCI configuration-space access via I/O ports (PCI_ADDR_PORT 0xCF8 / PCI_DATA_PORT 0xCFC). pci_init() enumerates the bus into a flat table (pci_devices[], up to PCI_MAX_DEVICES = 128); pci_probe_all() then walks it once and offers each device to the registered drivers. This is the bind point for the NICs (networking), the SVGA II display backend (video), and bus-master IDE DMA (ide).

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Driver model

A pci_driver_t matches either by vendor/device id (match_class = 0, device = PCI_MATCH_ANY to match any device of a vendor) or by class/subclass (match_class = 1). pci_probe_all() calls each matched driver’s probe(dev); returning 0 claims the device (sets dev->driver).

void pci_register_driver(const pci_driver_t *drv);   /* register before pci_probe_all */
int  pci_probe_all(void);                            /* returns devices bound */

Boot order: drivers register (ide_pci_register, virtio_net_register, rtl8139_register, e1000_register, pcnet_register), then pci_init() scans, then pci_probe_all() binds.

Config + BAR helpers (for bound drivers)

Function	Role
pci_read8/16/32, pci_write32(bus,dev,func,off,…)	Raw config-space access.
pci_enable_bus_master(d)	Set the bus-master bit (DMA-capable devices).
pci_bar_io(d,idx)	I/O base (BAR & ~0x3).
pci_bar_mem(d,idx)	MMIO base (BAR & ~0xF).
pci_class_name / pci_vendor_name / pci_device_name	Human names for lspci / boot logs.

pci_device_t

bus/dev/func, vendor_id, device_id, class_code, subclass, prog_if, revision_id, header_type, irq_line, bar[6], and driver (the bound driver’s name, NULL if unclaimed). The userspace lspci tool formats this table.