OPENPROM(4) | Device Drivers Manual (sparc) | 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

# 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.

June 5, 1993 | NetBSD 10.1