Attach Entry Point

The system calls attach(9E) to attach a device instance to the system or to resume operation after power has been suspended. The driver's attach(9E) entry point should handle these commands:

• DDI_ATTACH: Initialize the device instance.

• DDI_PM_RESUME: Restore the hardware state of a device after the device has been suspended.

• DDI_RESUME: Restore the hardware state of a device after the system has been suspended.

DDI_PM_RESUME Command

When power is restored to the device that was suspended with DDI_PM_SUSPEND, that device is resumed using the DDI_PM_RESUME command. The device driver should restore the hardware state, set up timeouts again if necessary, and enable interrupts again.

The DDI_PM_RESUME code should make no assumptions about the state of the hardware, which may or may not have lost power.

DDI_RESUME Command

When power is restored to the system or the system is unquiesced, each device that was suspended will be resumed using the DDI_RESUME command. The device driver should restore the hardware state, set up timeouts again if necessary, and enable interrupts again.

If the device is still suspended by DDI_PM_SUSPEND, the driver has to enter a state where it will call ddi_dev_is_needed(9F) for any new or pending requests, since an attach(9E) with DDI_PM_RESUME is still forthcoming.

The resume code should make no assumptions about the state of the hardware, which may or may not have lost power.