openprom(7D)
NAME
openprom - PROM monitor configuration interface
SYNOPSIS
#include <sys/fcntl.h>
#include <sys/types.h>
#include <sys/openpromio.h>
open("/dev/openprom", mode);
DESCRIPTION
The internal encoding of the configuration information
stored in EEPROM or NVRAM varies from model to model, and on
some systems the encoding is "hidden" by the firmware. The
openprom driver provides a consistent interface that allows
a user or program to inspect and modify that configuration,
using ioctl(2) requests. These requests are defined in
<sys/openpromio.h>:
struct openpromio {
uint_t oprom_size; /* real size of following data */
union {
char b[1]; /* NB: Adjacent, Null terminated */
int i;
} opio_u;
};
#define oprom_array opio_u.b /* property name/value array */
#define oprom_node opio_u.i /* nodeid from navigation config-ops */
#define oprom_len opio_u.i /* property len from OPROMGETPROPLEN */
#define OPROMMAXPARAM 32768 /* max size of array (advisory) */
For all ioctl(2) requests, the third parameter is a pointer
to a struct openpromio. All property names and values are
null-terminated strings; the value of a numeric option is
its ASCII representation.
For the raw ioctl(2) operations shown below that explicitly
or implicitly specify a nodeid, an error may be returned.
This is due to the removal of the node from the firmware
device tree by a Dynamic Reconfiguration operation. Programs
should decide if the appropriate response is to restart the
scanning operation from the beginning or terminate, inform-
ing the user that the tree has changed.
IOCTLS
OPROMGETOPT
This ioctl takes the null-terminated name of a pro-
perty in the oprom_array and returns its null-
terminated value (overlaying its name). oprom_size
should be set to the size of oprom_array; on return it
will contain the size of the returned value. If the
named property does not exist, or if there is not
enough space to hold its value, then oprom_size will
be set to zero. See BUGS below.
OPROMSETOPT
This ioctl takes two adjacent strings in oprom_array;
the null-terminated property name followed by the
null-terminated value.
OPROMSETOPT2
This ioctl is similar to OPROMSETOPT, except that it
uses the difference between the actual user array size
and the length of the property name plus its null ter-
minator.
OPROMNXTOPT
This ioctl is used to retrieve properties sequen-
tially. The null-terminated name of a property is
placed into oprom_array and on return it is replaced
with the null-terminated name of the next property in
the sequence, with oprom_size set to its length. A
null string on input means return the name of the
first property; an oprom_size of zero on output means
there are no more properties.
OPROMNXT
OPROMCHILD
OPROMGETPROP
OPROMNXTPROP
These ioctls provide an interface to the raw
config_ops operations in the PROM monitor. One can
use them to traverse the system device tree; see
prtconf(1M).
OPROMGETPROPLEN
This ioctl provides an interface to the property
length raw config op. It takes the name of a property
in the buffer, and returns an integer in the buffer.
It returns the integer -1 if the property does not
exist; 0 if the property exists, but has no value (a
boolean property); or a positive integer which is the
length of the property as reported by the PROM moni-
tor. See BUGS below.
OPROMGETVERSION
This ioctl returns an arbitrary and platform-dependent
NULL-terminated string in oprom_array, representing
the underlying version of the firmware.
ERRORS
EAGAIN
There are too many opens of the /dev/openprom device.
EFAULT
A bad address has been passed to an ioctl(2) routine.
EINVAL
The size value was invalid, or (for OPROMSETOPT) the
property does not exist, or an invalid ioctl is
being issued, or the ioctl is not supported by the
firmware, or the nodeid specified does not exist in
the firmware device tree.
ENOMEM
The kernel could not allocate space to copy the user's
structure.
EPERM Attempts have been made to write to a read-only
entity, or read from a write only entity.
ENXIO Attempting to open a non-existent device.
EXAMPLES
Example 1: oprom_array Data Allocation and Reuse
The following example shows how the oprom_array is allocated
and reused for data returned by the driver.
/*
* This program opens the openprom device and prints the platform
* name (root node name property) and the prom version.
*
* NOTE: /dev/openprom is readable only by user 'root' or group 'sys'.
*/
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/openpromio.h>
#define min(a, b) (a < b ? a : b)
#define max(a, b) (a > b ? a : b)
#define MAXNAMESZ 32 /* Maximum property *name* size */
#define BUFSZ 1024 /* A Handly default buffer size */
#define MAXVALSZ (BUFSZ - sizeof (int))
static char *promdev = "/dev/openprom";
/*
* Allocate an openpromio structure big enough to contain
* a bufsize'd oprom_array. Zero out the structure and
* set the oprom_size field to bufsize.
*/
static struct openpromio *
opp_zalloc(size_t bufsize)
{
struct openpromio *opp;
opp = malloc(sizeof (struct openpromio) + bufsize);
(void) memset(opp, 0, sizeof (struct openpromio) + bufsize);
opp->oprom_size = bufsize;
return (opp);
}
/*
* Free a 'struct openpromio' allocated by opp_zalloc
*/
static void
opp_free(struct openpromio *opp)
{
free(opp);
}
/*
* Get the peer node of the given node. The root node is the peer of zero.
* After changing nodes, property lookups apply to that node. The driver
* 'remembers' what node you are in.
*/
static int
peer(int nodeid, int fd)
{
struct openpromio *opp;
int i;
opp = opp_zalloc(sizeof (int));
opp->oprom_node = nodeid;
if (ioctl(fd, OPROMNEXT, opp) < 0) {
perror("OPROMNEXT");
exit(1);
}
i = opp->oprom_node;
opp_free(opp);
return(i);
}
int
main(void)
{
struct openpromio *opp;
int fd, proplen;
size_t buflen;
if ((fd = open(promdev, O_RDONLY)) < 0) {
fprintf(stderr, "Cannot open openprom device0);
exit(1);
}
/*
* Get and print the length and value of the
* root node 'name' property
*/
(void) peer(0, fd); /* Navigate to the root node */
/*
* Allocate an openpromio structure sized big enough to
* take the string "name" as input and return the int-sized
* length of the 'name' property.
* Then, get the length of the 'name' property.
*/
buflen = max(sizeof (int), strlen("name") + 1);
opp = opp_zalloc(buflen);
(void) strcpy(opp->oprom_array, "name");
if (ioctl(fd, OPROMGETPROPLEN, opp) < 0) {
perror("OPROMGETPROPLEN");
/* exit(1); */
proplen = 0; /* down-rev driver? */
} else
proplen = opp->oprom_len;
opp_free(opp);
if (proplen == -1) {
printf("'name' property does not exist!0);
exit (1);
}
/*
* Allocate an openpromio structure sized big enough
* to take the string 'name' as input and to return
* 'proplen + 1' bytes. Then, get the value of the
* 'name' property. Note how we make sure to size the
* array at least one byte more than the returned length
* to guarantee NULL termination.
*/
buflen = (proplen ? proplen + 1 : MAXVALSZ);
buflen = max(buflen, strlen("name") + 1);
opp = opp_zalloc(buflen);
(void) strcpy(opp->oprom_array, "name");
if (ioctl(fd, OPROMGETPROP, opp) < 0) {
perror("OPROMGETPROP");
exit(1);
}
if (opp->oprom_size != 0)
printf("Platform name <%s> property len <%d>0,
opp->oprom_array, proplen);
opp_free(opp);
/*
* Allocate an openpromio structure assumed to be
* big enough to get the 'prom version string'.
* Get and print the prom version.
*/
opp_zalloc(MAXVALSZ);
opp->oprom_size = MAXVALSZ;
if (ioctl(fd, OPROMGETVERSION, opp) < 0) {
perror("OPROMGETVERSION");
exit(1);
}
printf("Prom version <%s>0, opp->oprom_array);
opp_free(opp);
(void) close(fd);
return (0);
}
FILES
/dev/openprom
PROM monitor configuration interface
SEE ALSO
eeprom(1M), monitor(1M), prtconf(1M), ioctl(2), mem(7D)
BUGS
There should be separate return values for non-existent pro-
perties as opposed to not enough space for the value.
An attempt to set a property to an illegal value results in
the PROM setting it to some legal value, with no error being
returned. An OPROMGETOPT should be performed after an OPROM-
SETOPT to verify that the set worked.
Some PROMS lie about the property length of some string pro-
perties, omitting the NULL terminator from the property
length. The openprom driver attempts to transparently com-
pensate for these bugs when returning property values by
NULL terminating an extra character in the user buffer if
space is available in the user buffer. This extra character
is excluded from the oprom_size field returned from
OPROMGETPROP and OPROMGETOPT and excluded in the oprom_len
field returned from OPROMGETPROPLEN but is returned in the
user buffer from the calls that return data, if the user
buffer is allocated at least one byte larger than the pro-
perty length.
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