openprom(7D) Devices openprom(7D)NAMEopenprom - 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 con‐
figuration, 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 implic‐
itly 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 Recon‐
figuration operation. Programs should decide if the appropriate
response is to restart the scanning operation from the beginning or
terminate, informing the user that the tree has changed.
IOCTLS
OPROMGETOPT This ioctl takes the null-terminated name of a
property 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 terminator.
OPROMNXTOPT This ioctl is used to retrieve properties
sequentially. 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 prop‐
erty; an oprom_size of zero on output means
there are no more properties.
OPROMNXT These ioctls provide an interface to the raw
OPROMCHILD config_ops operations in the PROM monitor. One
OPROMGETPROP can use them to traverse the system device
OPROMNXTPROP tree; see prtconf(1M).
OPROMGETPROPLEN This ioctl provides an interface to the prop‐
erty length raw config op. It takes the name of
a property in the buffer, and returns an inte‐
ger 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 monitor.
See BUGS below.
OPROMGETVERSION This ioctl returns an arbitrary and platform-
dependent NULL-terminated string in
oprom_array, representing the underlying ver‐
sion 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 device\n");
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!\n");
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>\n",
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>\n", opp->oprom_array);
opp_free(opp);
(void) close(fd);
return (0);
}
FILES
/dev/openprom PROM monitor configuration interface
SEE ALSOeeprom(1M), monitor(1M), prtconf(1M), ioctl(2), mem(7D)BUGS
There should be separate return values for non-existent properties 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 OPROMSETOPT to verify that the
set worked.
Some PROMS lie about the property length of some string properties,
omitting the NULL terminator from the property length. The openprom
driver attempts to transparently compensate for these bugs when return‐
ing 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 OPROMGET‐
PROPLEN 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
property length.
SunOS 5.10 13 Jan 1997 openprom(7D)
