Driver API

Driver API

API for developing hardware drivers in ModuOS.

Driver Structure

typedef struct {
    const char *name;
    int (*init)(void);
    int (*probe)(void);
    void (*remove)(void);
} driver_t;

PCI Driver

PCI Device Structure

typedef struct {
    uint8_t bus;
    uint8_t device;
    uint8_t function;
    uint16_t vendor_id;
    uint16_t device_id;
    uint8_t class_code;
    uint8_t subclass;
    uint32_t bar[6];
} pci_device_t;

PCI Functions

// Find device by vendor/device ID
pci_device_t* pci_find_device(uint16_t vendor_id, uint16_t device_id);

// Find device by class
pci_device_t* pci_find_class(uint8_t class_code, uint8_t subclass);

// Enable bus mastering
void pci_enable_bus_mastering(pci_device_t *dev);

// Read BAR
uint32_t pci_read_bar(pci_device_t *dev, int bar_num);

Example PCI Driver

int mydriver_init(void) {
    // Find device
    pci_device_t *dev = pci_find_device(VENDOR_ID, DEVICE_ID);
    if (!dev) {
        return -1;
    }
    
    // Enable device
    pci_enable_bus_mastering(dev);
    pci_enable_memory_space(dev);
    
    // Map BARs
    uint32_t bar0 = pci_read_bar(dev, 0);
    
    // Initialize hardware
    // ...
    
    return 0;
}

IRQ Handling

Register IRQ Handler

void irq_register_handler(int irq, irq_handler_t handler);

void my_irq_handler(registers_t *regs) {
    // Handle interrupt
    // ...
}

// In driver init:
irq_register_handler(IRQ_NUM, my_irq_handler);

I/O Operations

Port I/O

// Read from I/O port
uint8_t inb(uint16_t port);
uint16_t inw(uint16_t port);
uint32_t inl(uint16_t port);

// Write to I/O port
void outb(uint16_t port, uint8_t value);
void outw(uint16_t port, uint16_t value);
void outl(uint16_t port, uint32_t value);

Memory-Mapped I/O

// Map physical address to virtual
void *ioremap(uint64_t phys_addr, size_t size);

// Access memory-mapped registers
volatile uint32_t *regs = (volatile uint32_t*)ioremap(bar0, 0x1000);
uint32_t status = regs[0];
regs[1] = command;

Next Steps

• Device Drivers - Driver overview
• PCI Subsystem - PCI details