Intro(9E)
NAME
Intro − introduction to device driver entry points
DESCRIPTION
Section 9E describes the DDI/DKI, DDI-only, and DKI-only entry-point routines a developer may 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 for STREAMS drivers, in response to STREAMS events.
Functions provided to allow the driver to communicate with the kernel 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 routines named prefixopen, prefixclose, prefixread, prefixwrite, and so forth. 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. These entry points may be used in either DDI or DKI, except as noted.
| Routine | Type |
| _fini | SPARC DDI |
| _info | SPARC DDI |
| _init | SPARC DDI |
| attach | SPARC DDI |
| chpoll | DDI/DKI |
| close | DDI/DKI |
| detach | SPARC DDI |
| dump | SPARC DDI |
| getinfo | SPARC DDI |
| identify | SPARC DDI |
| ioctl | DDI/DKI |
| mmap | DKI only |
| open | DDI/DKI |
| DDI/DKI | |
| probe | SPARC DDI |
| prop_op | SPARC DDI |
| read | DDI/DKI |
| segmap | DKI only |
| strategy | DDI/DKI |
| write | DDI/DKI |
The table below lists the error codes that should be returned by a driver routine when an error is encountered. It lists the error values in alphabetic order. All the error values 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 returning the value. 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, as the function that it calls, cmn_err(9F), is declared as void (no error is returned).
Driver Error Codes
| Error | Use in these | |
| Value | Error Description | Driver Routines (9E) |
| 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). | open, ioctl, read, write, strategy |
| EFAULT | An invalid address has been passed as an argument; memory addressing error. | open, close, ioctl, read, write, strategy |
| EINTR | Sleep interrupted by signal. | open, close, ioctl, read, write, strategy |
| EINVAL | An invalid argument was passed to the routine. | open, ioctl, read, write, strategy |
| EIO | A device error occurred; an error condition was detected in a device status register (the I/O request was valid, but an error occurred on the device). | open, close, ioctl, read, write, 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. | open, close, ioctl, read, write, strategy |
| EPERM | A process attempting an operation did not have required permission. | open, ioctl, read, write, close |
| EROFS | An attempt was made to open for writing a read-only device. | open |
The table below cross references error values to the driver routines from which the error values can be returned.
| read, write, | |||
| open | close | ioctl | 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 |
LIST OF Entry Points
NameAppears on PageDescription
_fini_fini(9E)loadable module entry points
_info_fini(9E)loadable module entry points
_init_fini(9E)loadable module entry points
attachattach(9E)attach a device to the system
chpollchpoll(9E)poll entry point for non-STREAMS character driver
closeclose(9E)relinquish access to a device
detachdetach(9E)detach a device
dumpdump(9E)dump memory to disk during system failure
getinfogetinfo(9E)get device driver information
identifyidentify(9E)claim to drive a device
ioctlioctl(9E)control a character device
mmapmmap(9E)check virtual mapping for memory mapped device
openopen(9E)gain access to a device
printprint(9E)display a driver message on system console
probeprobe(9E)determine if a non-self-identifying device is present
prop_opprop_op(9E)report driver property information
putput(9E)receive messages from the preceding queue
readread(9E)read data from a device
segmapsegmap(9E)map device memory into user space
srvsrv(9E)service queued messages
strategystrategy(9E)perform block I/O
writewrite(9E)write data to a device
SunOS 5.1 — Last change: 2 Oct 1992