Intro(9E) Driver Entry Points Intro(9E)NAME
Intro, intro - overview of device driver interfaces and introduction to
driver entry points
DESCRIPTION
This page provides an overview of device driver interfaces and all of
the Section 9 man pages (9E, 9F, 9P, and 9S). This overview is followed
by an introduction to Section 9E, the driver entry-point routines.
Overview of Device Driver Interfaces
Section 9 provides reference information needed to write device drivers
for the Solaris operating environment. It describes the interfaces pro‐
vided by the Device Driver Interface and the Driver-Kernel Interface
(DDI/DKI).
Porting
Software is usually considered portable if it can be adapted to run in
a different environment more cheaply than it can be rewritten. The new
environment may include a different processor, operating system, and
even the language in which the program is written, if a language trans‐
lator is available. Likewise the new environment might include multi‐
ple processors. More often, however, software is ported between envi‐
ronments that share an operating system, processor, and source lan‐
guage. The source code is modified to accommodate the differences in
compilers or processors or releases of the operating system.
In the past, device drivers did not port easily for one or more of the
following reasons:
· To enhance functionality, members had been added to kernel data
structures accessed by drivers, or the sizes of existing members
had been redefined.
· The calling or return syntax of kernel functions had changed.
· Driver developers did not use existing kernel functions where
available, or relied on undocumented side effects that were not
maintained in the next release.
· Architecture-specific code had been scattered throughout the
driver when it could have been isolated.
Operating systems are periodically reissued to customers as a way to
improve performance, fix bugs, and add new features. This is probably
the most common threat to compatibility encountered by developers
responsible for maintaining software. Another common problem is upgrad‐
ing hardware. As new hardware is developed, customers occasionally
decide to upgrade to faster, more capable computers of the same family.
Although they may run the same operating system as those being
replaced, architecture-specific code may prevent the software from
porting.
Scope of Interfaces
Although application programs have all of the porting problems men‐
tioned, developers attempting to port device drivers have special chal‐
lenges. Before describing the DDI/DKI, it is necessary to understand
the position of device drivers in operating systems.
Device drivers are kernel modules that control data transferred to and
received from peripheral devices but are developed independently from
the rest of the kernel. If the goal of achieving complete freedom in
modifying the kernel is to be reconciled with the goal of binary com‐
patibility with existing drivers, the interaction between drivers and
the kernel must be rigorously regulated. This driver/kernel service
interface is the most important of the three distinguishable interfaces
for a driver, summarized as follows:
· Driver-Kernel. I/O System calls result in calls to driver entry
point routines. These make up the kernel-to-driver part of the
service interface, described in Section 9E. Drivers may call any
of the functions described in Section 9F. These are the driver-to-
kernel part of the interface.
· Driver-Hardware. All drivers (except software drivers) must
include code for interrupt handling, and may also perform direct
memory access (DMA). These and other hardware-specific interac‐
tions make up the driver/hardware interface.
· Driver-Boot/Configuration Software. The interaction between the
driver and the boot and configuration software is the third inter‐
face affecting drivers.
Scope of the DDI/DKI
The primary goal of the DDI/DKI is to facilitate both source and binary
portability across successive releases of the operating systems on a
particular machine. In addition, it promotes source portability across
implementations of UNIX on different machines, and applies only to
implementations based on System V Release 4. The DDI/DKI consists of
several sections:
· DDI/DKI Architecture Independent - These interfaces are supported
on all implementations of System V Release 4.
· DKI-only - These interfaces are part of System V Release 4, and
may not be supported in future releases of System V. There are
only two interfaces in this class, segmap(9E) and
hat_getkpfnum(9F)
· Solaris DDI - These interfaces specific to Solaris.
· Solaris SPARC specific DDI - These interfaces are specific to the
SPARC processor, and may not be available on other processors sup‐
ported by Solaris.
· Solaris x86 specific DDI - These interfaces are specific to the
x86 processor, and may not be available on other processors sup‐
ported by Solaris.
To achieve the goal of source and binary compatibility, the functions,
routines, and structures specified in the DDI/DKI must be used accord‐
ing to these rules.
· Drivers cannot access system state structures (for example, u and
sysinfo) directly.
· For structures external to the driver that may be accessed
directly, only the utility functions provided in Section 9F should
be used. More generally, these functions should be used wherever
possible.
· The headers <sys/ddi.h> and <sys/sunddi.h> must be the last header
files included by the driver.
Audience
Section 9 is for software engineers responsible for creating, modify‐
ing, or maintaining drivers that run on this operating system and
beyond. It assumes that the reader is familiar with system internals
and the C programming language.
PCMCIA Standard
The PC Card 95 Standard is listed under the SEE ALSO heading in some
Section 9 reference pages. This refers to documentation published by
the Personal Computer Memory Card International Association (PCMCIA)
and the Japan Electronic Industry Development Association (JEIDA).
How to Use Section 9
Section 9 is divided into the following subsections:
9E Driver Entry Points - contains reference pages for all driver
entry point routines.
9F Kernel Functions - contains reference pages for all driver
support routines.
9P Driver Properties - contains reference pages for driver prop‐
erties.
9S Data Structures - contains reference pages for driver-related
structures.
Compatibility Note
Sun Microsystem's implementation of the DDI/DKI was designed to provide
binary compatibility for third-party device drivers across currently
supported hardware platforms across minor releases of the operating
system. However, unforeseen technical issues may force changes to the
binary interface of the DDI/DKI. We cannot therefore promise or in any
way assure that DDI/DKI-compliant device drivers will continue to oper‐
ate correctly on future releases.
Introduction to Section 9E
Section 9E describes the entry-point routines a developer can include
in a device driver. These are called entry-point because they provide
the calling and return syntax from the kernel into the driver. Entry-
points are called, for instance, in response to system calls, when the
driver is loaded, or in response to STREAMS events.
Kernel functions usable by the driver are described in section 9F.
In this section, reference pages contain the following headings:
· NAME describes the routine's purpose.
· SYNOPSIS summarizes the routine's calling and return syntax.
· INTERFACE LEVEL describes any architecture dependencies. It also
indicates whether the use of the entry point is required,
optional, or discouraged.
· ARGUMENTS describes each of the routine's arguments.
· DESCRIPTION provides general information about the routine.
· RETURN VALUES describes each of the routine's return values.
· SEE ALSO gives sources for further information.
Overview of Driver Entry-Point Routines and Naming Conventions
By convention, a prefix string is added to the driver routine names.
For a driver with the prefix prefix, the driver code may contain rou‐
tines named prefixopen, prefixclose, prefixread, prefixwrite, and so
forth. All global variables associated with the driver should also use
the same prefix.
All routines and data should be declared as static.
Every driver MUST include <sys/ddi.h> and <sys/sunddi.h>, in that
order, and after all other include files.
The following table summarizes the STREAMS driver entry points
described in this section.
Routine Type
put DDI/DKI
srv DDI/DKI
The following table summarizes the driver entry points described in
this section.
Routine Type
_fini Solaris DDI
_info Solaris DDI
_init Solaris DDI
aread Solaris DDI
attach Solaris DDI
awrite Solaris DDI
chpoll DDI/DKI
close DDI/DKI
detach Solaris DDI
devmap Solaris DDI
devmap_access Solaris DDI
devmap_contextmgt Solaris DDI
devmap_dup Solaris DDI
devmap_map Solaris DDI
devmap_unmap Solaris DDI
dump Solaris DDI
getinfo Solaris DDI
identify Solaris DDI
ioctl DDI/DKI
ks_update Solaris DDI
mapdev_access Solaris DDI
mapdev_dup Solaris DDI
mapdev_free Solaris DDI
mmap DKI only
open DDI/DKI
power Solaris DDI
print DDI/DKI
probe Solaris DDI
prop_op Solaris DDI
read DDI/DKI
segmap DKI only
strategy DDI/DKI
tran_abort Solaris DDI
tran_destroy_pkt Solaris DDI
tran_dmafree Solaris DDI
tran_getcap Solaris DDI
tran_init_pkt Solaris DDI
tran_reset Solaris DDI
tran_reset_notify Solaris DDI
tran_setcap Solaris DDI
tran_start Solaris DDI
tran_sync_pkt Solaris DDI
tran_tgt_free Solaris DDI
tran_tgt_init Solaris DDI
tran_tgt_probe Solaris DDI
write DDI/DKI
The following table lists the error codes returned by a driver routine
when it encounters an error. The error values are listed in alphabetic
order and are defined in sys/errno.h. In the driver open(9E),
close(9E), ioctl(9E), read(9E), and write(9E) routines, errors are
passed back to the user by calling bioerror(9F) to set b_flags to the
proper error code. In the driver strategy(9E) routine, errors are
passed back to the user by setting the b_error member of the buf(9S)
structure to the error code. For STREAMS ioctl routines, errors should
be sent upstream in an M_IOCNAK message. For STREAMS read() and write()
routines, errors should be sent upstream in an M_ERROR message. The
driver print routine should not return an error code because the func‐
tion that it calls, cmn_err(9F), is declared as void (no error is
returned).
Error Value Error Description
EAGAIN Kernel resources, such as the buf
structure or cache memory, are not
available at this time (device may be
busy, or the system resource is not
available). This is used in open,
ioctl, read, write, and strategy.
EFAULT An invalid address has been passed as
an argument; memory addressing error.
This is used in open, close, ioctl,
read, write, and strategy.
EINTR Sleep interrupted by signal. This is
used in open, close, ioctl, read,
write, and strategy.
EINVAL An invalid argument was passed to the
routine. This is used in open, ioctl,
read, write, and strategy.
EIO A device error occurred; an error con‐
dition was detected in a device status
register (the I/O request was valid,
but an error occurred on the device).
This is used in open, close, ioctl,
read, write, and strategy.
ENXIO An attempt was made to access a device
or subdevice that does not exist (one
that is not configured); an attempt
was made to perform an invalid I/O
operation; an incorrect minor number
was specified. This is used in open,
close, ioctl, read, write, and strat‐
egy.
EPERM A process attempting an operation did
not have required permission. This is
used in open, ioctl, read, write, and
strategy.
EROFS An attempt was made to open for writ‐
ing a read-only device. This is used
in open.
The table below cross references error values to the driver routines
from which the error values can be returned.
┌────────────┬─────────────┬──────────────┬─────────────────────────┐
│ open │ close │ ioctl │read, write and strategy │
│EAGAIN │ EFAULT │ EAGAIN │EAGAIN │
│EFAULT │ EINTR │ EFAULT │EFAULT │
│EINTR │ EIO │ EINTR │EINTR │
│EINVAL │ ENXIO │ EINVAL │EINVAL │
│EIO │ │ EIO │EIO │
│ENXIO │ │ ENXIO │ENXIO │
│EPERM │ │ EPERM │ │
│EROFS │ │ │ │
└────────────┴─────────────┴──────────────┴─────────────────────────┘
SEE ALSOintro(9F), intro(9S)List OF FUNCTIONS
Name Description
_fini(9E) loadable module configuration entry points
_info(9E) See _fini(9E)_init(9E) See _fini(9E)aread(9E) asynchronous read from a device
attach(9E) Attach a device to the system, or resume it
awrite(9E) asynchronous write to a device
chpoll(9E) poll entry point for a non-STREAMS character
driver
close(9E) relinquish access to a device
csx_event_handler(9E) PC Card driver event handler
detach(9E) detach or suspend a device
devmap(9E) validate and translate virtual mapping for mem‐
ory mapped device
devmap_access(9E) device mapping access entry point
devmap_contextmgt(9E) driver callback function for context management
devmap_dup(9E) device mapping duplication entry point
devmap_map(9E) device mapping create entry point
devmap_unmap(9E) device mapping unmap entry point
dump(9E) dump memory to device during system failure
getinfo(9E) get device driver information
gld(9E) Generic LAN Driver entry points
gldm_get_stats(9E) See gld(9E)gldm_intr(9E) See gld(9E)gldm_ioctl(9E) See gld(9E)gldm_reset(9E) See gld(9E)gldm_send(9E) See gld(9E)gldm_set_mac_addr(9E) See gld(9E)gldm_set_multicast(9E) See gld(9E)gldm_set_promiscuous(9E)See gld(9E)gldm_start(9E) See gld(9E)gldm_stop(9E) See gld(9E)identify(9E) determine if a driver is associated with a
device
ioctl(9E) control a character device
ks_snapshot(9E) take a snapshot of kstat data
ks_update(9E) dynamically update kstats
mmap(9E) check virtual mapping for memory mapped device
open(9E) gain access to a device
power(9E) power a device attached to the system
print(9E) display a driver message on system console
probe(9E) determine if a non-self-identifying device is
present
prop_op(9E) report driver property information
put(9E) receive messages from the preceding queue
read(9E) read data from a device
segmap(9E) map device memory into user space
srv(9E) service queued messages
strategy(9E) perform block I/O
tran_abort(9E) abort a SCSI command
tran_bus_reset(9e) reset a SCSI bus
tran_destroy_pkt(9E) See tran_init_pkt(9E)tran_dmafree(9E) SCSI HBA DMA deallocation entry point
tran_getcap(9E) get/set SCSI transport capability
tran_init_pkt(9E) SCSI HBA packet preparation and deallocation
tran_quiesce(9e) quiesce and unquiesce a SCSI bus
tran_reset(9E) reset a SCSI bus or target
tran_reset_notify(9E) request to notify SCSI target of bus reset
tran_setcap(9E) See tran_getcap(9E)tran_start(9E) request to transport a SCSI command
tran_sync_pkt(9E) SCSI HBA memory synchronization entry point
tran_tgt_free(9E) request to free HBA resources allocated on
behalf of a target
tran_tgt_init(9E) request to initialize HBA resources on behalf
of a particular target
tran_tgt_probe(9E) request to probe SCSI bus for a particular tar‐
get
tran_unquiesce(9e) See tran_quiesce(9e)write(9E) write data to a device
SunOS 5.10 21 Dec 2004 Intro(9E)
