// 3. Set DMA mask (e.g., 64-bit addressing) dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));

static int my_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)

static int my_probe(struct pci_dev *pdev, const struct pci_device_id *id)

// 4. Map BAR0 (control registers) into kernel virtual address space void __iomem *regs = pci_iomap(pdev, 0, 0);

// 1. Enable the PCI device pci_enable_device(pdev); // 2. Request ownership of memory regions (BARs) pci_request_regions(pdev, "my_driver");

#include <linux/pci.h> #include <linux/module.h> static const struct pci_device_id my_ids[] = PCI_DEVICE(0x1234, 0x5678) , 0, ; MODULE_DEVICE_TABLE(pci, my_ids);

In modern computing, the Peripheral Component Interconnect (PCI) bus is the circulatory system of the motherboard. From GPUs and NVMe SSDs to network adapters and sound cards, almost every high-speed peripheral relies on PCI or its derivatives (PCIe).

| Feature | Impact on Driver | |---------|------------------| | | Use pci_read_config_dword() for offsets up to 4095. | | Message Signaled Interrupts (MSI/MSI-X) | Prefer pci_alloc_irq_vectors() over legacy IRQ. Enables per-vector affinity. | | Atomic Operations | Not directly visible to drivers, but lower latency benefits. | | Power Management (ASPM) | Driver may need to pci_disable_link_state() to avoid performance regressions. |