OPENPROM(4)

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: http://www.openfirmware.org/1275/

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.