OPENPROM(4) BSD/sparc Kernel Interfaces Manual OPENPROM(4)NAMEopenprom — OPENPROM and EEPROM interface
The file /dev/openprom is an interface to the SPARC OPENPROM, including
the EEPROM area. This interface is highly stylized; ioctls are used for
all operations. These ioctls refer to “nodes”, which are simply “magic”
integer values describing data areas. Occasionally the number 0 may be
used or returned instead, as described below. A special distinguished
“options” node holds the EEPROM settings.
The calls that take and/or return a node use a pointer to an int variable
for this purpose; others use a pointer to an struct opiocdesc descriptor,
which contains a node and two counted strings. The first string is com‐
prised of the fields op_namelen (an int) and op_name (a char *), giving
the name of a field. The second string is comprised of the fields
op_buflen and op_buf, used analogously. These two counted strings work
in a “value-result” fashion. At entry to the ioctl, the counts are
expected to reflect the buffer size; on return, the counts are updated to
reflect the buffer contents.
The following ioctls are supported:
OPIOCGETOPTNODE Takes nothing, and fills in the options node number.
OPIOCGETNEXT Takes a node number and returns the number of the fol‐
lowing node. The node following the last node is number
0; the node following number 0 is the first node.
OPIOCGETCHILD Takes a node number and returns the number of the first
“child” of that node. This child may have siblings;
these can be discovered by using OPIOCGETNEXT.
OPIOCGET Fills in the value of the named property for the given
node. If no such property is associated with that node,
the value length is set to -1. If the named property
exists but has no value, the value length is set to 0.
OPIOCSET Writes the given value under the given name. The OPEN‐
PROM may refuse this operation; in this case EINVAL is
OPIOCNEXTPROP Finds the property whose name follows the given name in
OPENPROM internal order. The resulting name is returned
in the value field. If the named property is the last,
the “next” name is the empty string. As with
OPIOCGETNEXT, the next name after the empty string is
the first name.
The following may result in rejection of an operation:
[EINVAL] The given node number is not zero and does not corre‐
spond to any valid node, or is zero where zero is not
[EBADF] The requested operation requires permissions not spec‐
ified at the call to open().
[ENAMETOOLONG] The given name or value field exceeds the maximum
allowed length (8191 bytes).
Due to limitations within the OPENPROM itself, these functions run at
elevated priority and may adversely affect system performance.
BSD June 5, 1993 BSD