DDI_DEVID_COMPARE(9F) Kernel Functions for Drivers DDI_DEVID_COMPARE(9F)

NAME

ddi_devid_compare, ddi_devid_free, ddi_devid_init, ddi_devid_register,
ddi_devid_sizeof, ddi_devid_str_decode, ddi_devid_str_encode,
ddi_devid_str_free, ddi_devid_get, ddi_devid_unregister, ddi_devid_valid
- kernel interfaces for device ids

SYNOPSIS

int ddi_devid_compare(ddi_devid_t devid1, ddi_devid_t devid2);


size_t ddi_devid_sizeof(ddi_devid_t devid);


int ddi_devid_init(dev_info_t *dip, ushort_t devid_type,
ushort_t nbytes, void *id, ddi_devid_t *retdevid);


void ddi_devid_free(ddi_devid_t devid);


int ddi_devid_register(dev_info_t *dip, ddi_devid_t devid);


int ddi_devid_str_decode(char *devidstr, ddi_devid_t *retdevid,
char **retminor_name);


int ddi_devid_str_encode(ddi_devid_t devid, char *minor_name);


int ddi_devid_str_free(char *devidstr);


int ddi_devid_get(dev_info_t *dip, ddi_devid_t *retdevid);


void ddi_devid_unregister(dev_info_t *dip);


int ddi_devid_valid(ddi_devid_t devid);

PARAMETERS

devid
The device id address.


devidstr
The devid and minor_name represented as a string.


devid1
The first of two device id addresses to be compared calling
ddi_devid_compare().


devid2
The second of two device id addresses to be compared
calling ddi_devid_compare().


dip
A dev_info pointer, which identifies the device.


devid_type
The following device id types may be accepted by the
ddi_devid_init() function:

DEVID_SCSI3_WWN
World Wide Name associated with SCSI-3
devices.


DEVID_SCSI_SERIAL
Vendor IDand serial number associated
with a SCSI device. Note: This may
only be used if known to be unique;
otherwise a fabricated device id must
be used.


DEVID_ENCAP
Device ID of another device. This is
for layered device driver usage.


DEVID_FAB
Fabricated device ID.


minor_name
The minor name to be encoded.


nbytes
The length in bytes of device ID.


retdevid
The return address of the device ID.


retminor_name
The return address of a minor name. Free string with
ddi_devid_str_free().

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

DESCRIPTION

The following routines are used to provide unique identifiers, device
IDs, for devices. Specifically, kernel modules use these interfaces to
identify and locate devices, independent of the device's physical
connection or its logical device name or number.


ddi_devid_compare() compares two device IDs byte-by-byte and determines
both equality and sort order.


ddi_devid_sizeof() returns the number of bytes allocated for the passed
in device ID (devid).


ddi_devid_init() allocates memory and initializes the opaque device ID
structure. This function does not store the devid. If the device id is
not derived from the device's firmware, it is the driver's responsibility
to store the devid on some reliable store. When a devid_type of either
DEVID_SCSI3_WWN, DEVID_SCSI_SERIAL, or DEVID_ENCAP is accepted, an array
of bytes (id) must be passed in (nbytes).


When the devid_type DEVID_FAB is used, the array of bytes (id) must be
NULL and the length (nbytes) must be zero. The fabricated device ids,
DEVID_FAB will be initialized with the machine's host id and a timestamp.


Drivers must free the memory allocated by this function, using the
ddi_devid_free() function.


ddi_devid_free() frees the memory allocated for the returned devid by the
ddi_devid_init() and devid_str_decode() functions.


ddi_devid_register() registers the device ID address (devid) with the DDI
framework, associating it with the dev_info passed in (dip). The drivers
must register device IDs at attach time. See attach(9E).


ddi_devid_unregister() removes the device ID address from the dev_info
passed in (dip). Drivers must use this function to unregister the device
ID when devices are being detached. This function does not free the space
allocated for the device ID. The driver must free the space allocated for
the device ID, using the ddi_devid_free() function. See detach(9E).


ddi_devid_valid() validates the device ID (devid) passed in. The driver
must use this function to validate any fabricated device ID that has been
stored on a device.


The ddi_devid_get() function returns a pointer to the device ID structure
through retdevid if there is already a registered device ID associated
with the dev_info node. A driver can use this interface to check and get
the device ID associated with the dev_info node. It returns DDI_FAILURE
if no device ID is registered for the node.


The ddi_devid_get() function allocates memory for the opaque device ID
structure and initializes it with the associated device ID and returns
the pointer to it. The driver must free the memory allocated by this
function using the ddi_devid_free() function.


The ddi_devid_str_encode() function encodes a devid and minor_name into a
null-terminated ASCII string, returning a pointer to that string. If both
a devid and a minor_name are non-null, then a slash (/) is used to
separate the devid from the minor_name in the encoded string. If
minor_name is null, then only the devid is encoded. If the devid is null,
then the special string id0 is returned. Note that you cannot compare the
returned string against another string with strcmp() to determine devid
equality. The returned string must be freed by calling devid_str_free().


The ddi_devid_str_decode() function takes a string previously produced by
the devid_str_encode(3DEVID) or ddi_devid_str_encode() function and
decodes the contained device ID and minor_name, allocating and returning
pointers to the extracted parts through the retdevid and retminor_name
arguments. If the special devidstr id0 was specified then the returned
device ID and minor name will both be null. A non-null returned devid
must be freed by the caller through the ddi_devid_free() function. A non-
null returned minor name must be freed by calling ddi_devid_str_free().


The ddi_devid_str_free() function is used to free all strings returned by
the ddi_devid functions (the ddi_devid_str_encode() function return value
and the returned retminor_name argument).

RETURN VALUES

ddi_devid_init() returns the following values:


DDI_SUCCESS
Success.


DDI_FAILURE
Out of memory. An invalid devid_type was passed in.


ddi_devid_valid() returns the following values:


DDI_SUCCESS
Valid device ID.


DDI_FAILURE
Invalid device ID.


ddi_devid_register() returns the following values:


DDI_SUCCESS
Success.


DDI_FAILURE
Failure. The device ID is already registered or the
device ID is invalid.


ddi_devid_valid() returns the following values:


DDI_SUCCESS
Valid device ID.


DDI_FAILURE
Invalid device ID.


ddi_devid_get() returns the following values:


DDI_SUCCESS
Device ID is present and a pointer to it is returned
in retdevid.


DDI_FAILURE
No device ID is defined for this dev_info node.


ddi_devid_compare() returns the following values:


-1
The first device ID is less than the second device ID.


0
The first device ID is equal to the second device ID.


1
The first device ID is greater than the second device ID.


ddi_devid_sizeof() returns the size of the devid in bytes. If called with
a null, then the number of bytes that must be allocated and initialized
to determine the size of a complete device ID is returned.


ddi_devid_str_encode() returns a value of null to indicate failure.
Failure can be caused by attempting to encode an invalid devid. If the
return value is non-null then the caller must free the returned string by
using the devid_str_free() function.


ddi_devid_str_decode() returns the following values:


DDI_SUCCESS
Success.


DDI_FAILURE
Failure; the devidstr string was not valid.

CONTEXT

These functions can be called from a user or kernel context.

SEE ALSO

devid_get(3DEVID), libdevid(3LIB), attributes(7), attach(9E), detach(9E),
kmem_free(9F)


Writing Device Drivers

May 23, 2021 DDI_DEVID_COMPARE(9F)