18.3 Newbus API

18.3.1 Important locations in the source hierarchy

src/sys/[arch]/[arch] - Kernel code for a specific machine architecture resides in this directory. for example, the i386 architecture, or the SPARC64 architecture.

src/sys/dev/[bus] - device support for a specific [bus] resides in this directory.

src/sys/dev/pci - PCI bus support code resides in this directory.

src/sys/[isa|pci] - PCI/ISA device drivers reside in this directory. The PCI/ISA bus support code used to exist in this directory in FreeBSD version 4.0.

18.3.2 Important structures and type definitions

devclass_t - This is a type definition of a pointer to a struct devclass.

device_method_t - This is same as kobj_method_t (see src/sys/kobj.h).

device_t - This is a type definition of a pointer to a struct device. device_t represents a device in the system. It is a kernel object. See src/sys/sys/bus_private.h for implementation details.

driver_t - This is a type definition which, references struct driver. The driver struct is a class of the device kernel object; it also holds data private to for the driver.

     struct driver {
            KOBJ_CLASS_FIELDS;
            void    *priv;          /* driver private data */
      };
   

A device_state_t type, which is an enumeration, device_state. It contains the possible states of a Newbus device before and after the autoconfiguration process.

     /*
       * src/sys/sys/bus.h
       */
      typedef enum device_state {
        DS_NOTPRESENT,  /* not probed or probe failed */
            DS_ALIVE,       /* probe succeeded */
            DS_ATTACHED,    /* attach method called */
            DS_BUSY         /* device is open */
      } device_state_t;