man/man9e/probe.9e

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 PROBE 9E "February 15, 2020"
 NAME
probe - determine if a non-self-identifying device is present
 SYNOPSIS
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>


static int prefixprobe(dev_info_t *dip);


 INTERFACE LEVEL
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.
 ARGUMENTS
dip

Pointer to the device's dev_info structure.


 DESCRIPTION
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 called.

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.
 RETURN VALUES
DDI_PROBE_SUCCESS

If the probe was successful.


DDI_PROBE_FAILURE

If the probe failed.


DDI_PROBE_DONTCARE

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


DDI_PROBE_PARTIAL

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


 SEE ALSO
 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