NAME
openprom —
Sun OPENPROM and EEPROM
interface
SYNOPSIS
#include <machine/openpromio.h>
DESCRIPTION
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 comprises the fields
op_namelen
(an
int
) and
op_name
(a
char *
), giving the
name of a field. The second string comprises 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 following
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 OPENPROM
may refuse this operation; in this case
EINVAL
is
returned.
-
-
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.
FILES
/dev/openprom
ERRORS
The following may result in rejection of an operation:
-
-
- [
EINVAL
]
- The given node number is not zero and does not correspond
to any valid node, or is zero where zero is not allowed.
-
-
- [
EBADF
]
- The requested operation requires permissions not specified
at the call to open().
-
-
- [
ENAMETOOLONG
]
- The given name or value field exceeds the maximum allowed
length (8191 bytes).
SEE ALSO
ioctl(2)
IEEE 1275 Open
Firmware
BUGS
Due to limitations within the
openprom itself, these functions
run at elevated priority and may adversely affect system performance.
The Sun
openprom is what became the Open Firmware (IEEE 1275)
standard for processor and system independent boot firmware.