PROBE(9E) Driver Entry Points PROBE(9E)


probe - determine if a non-self-identifying device is present


#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

static int prefixprobe(dev_info_t *dip);


illumos DDI specific (illumos DDI). This entry point is required for non-
self-identifying devices. You must write it for such devices. For self-
identifying devices, nulldev(9F) should be specified in the dev_ops(9S)
structure if a probe routine is not necessary.


Pointer to the device's dev_info structure.


probe() determines whether the device corresponding to dip actually
exists and is a valid device for this driver. probe() is called after
identify(9E) and before attach(9E) for a given dip. For example, the
probe() routine can map the device registers using ddi_map_regs(9F) then
attempt to access the hardware using ddi_peek(9F) or ddi_poke(9F) and
determine if the device exists. Then the device registers should be
unmapped using ddi_unmap_regs(9F).

To probe a device that was left powered off after the last detach(), it
might be necessary to power it up. If so, the driver must power up the
device by accessing device registers directly. pm_raise_power(9F) will be
not be available until attach(9E). The framework ensures that the
ancestors of the node being probed and all relevant platform-specific
power management hardware is at full power at the time that probe() is

probe() should only probe the device. It should not change any software
state and should not create any software state. Device initialization
should be done in attach(9E).

For a self-identifying device, this entry point is not necessary.
However, if a device exists in both self-identifying and non-self-
identifying forms, a probe() routine can be provided to simplify the
driver. ddi_dev_is_sid(9F) can then be used to determine whether probe()
needs to do any work. See ddi_dev_is_sid(9F) for an example.


If the probe was successful.

If the probe failed.

If the probe was unsuccessful, yet attach(9E)
should still be called.

If the instance is not present now, but may be
present in the future.


attach(9E), identify(9E), ddi_dev_is_sid(9F), ddi_map_regs(9F),
ddi_peek(9F), ddi_poke(9F), nulldev(9F), dev_ops(9S)

Writing Device Drivers

February 15, 2020 PROBE(9E)