DragonFly On-Line Manual Pages

DEVICE_GET_STATE(9)   DragonFly Kernel Developer's Manual  DEVICE_GET_STATE(9)


device_get_state, device_busy, device_unbusy, device_is_alive -- manipu- late device state


#include <sys/param.h> #include <sys/bus.h> device_state_t device_get_state(device_t dev); void device_busy(device_t dev); void device_unbusy(device_t dev); int device_is_alive(device_t dev);


The current state of a device is accessed by calling device_get_state(9) which returns DS_NOTPRESENT, DS_ALIVE, DS_ATTACHED or DS_BUSY (described in device(9)). To test see if a device was successfully probed, call device_is_alive(9) which simply returns if the state is greater or equal to DS_ALIVE. Each device has a busy count which is incremented when device_busy(9) is called and decremented when device_unbusy(9) is called. Both routines return an error if the device state is less than DS_ATTACHED. When device_busy(9) is called on a device in the DS_ATTACHED state, the device changes to the DS_BUSY state. When device_unbusy(9) is called and after decrementing, the busy count for the device is zero, the device changes to the DS_ATTACHED state.




This man page was written by Doug Rabson. DragonFly 3.7 June 16, 1998 DragonFly 3.7