FGA(4)

NAME
fga - SPARC Force FGA5000 VME/SBus bridge driver

SYNOPSIS
fga0 at iommu0
fvme* at fga0

DESCRIPTION
The fga driver provides a bridge between SBus and VME interfaces. It has support for accessing VME address and data spaces as if they were SBus address ranges, and mapping of VME interrupt levels to SBus interrupts. The fga also provides a set of semaphores and mailboxes which are accessible from user programs via ioctl(2).

VME devices are attached to the fvme pseudo-devices, which provide an interface for drivers to establish VME level/vectored interrupts and map address ranges. By default the following address ranges are established:
Size SBus Slot SBus Offset VME Space VME Offset
256MB | 1 | 0x0000000 | A32/D32 | 0xf0000000
256MB | 4 | 0x0000000 | A32/D16 | 0xf0000000
16MB | 5 | 0xe000000 | A24/D16 | 0x000000
64KB | 5 | 0xffc0000 | A16/D8 | 0x0000
64KB | 5 | 0xffd0000 | A16/D16 | 0x0000
64KB | 5 | 0xffe0000 | A16/D32 | 0x0000

The abort switch on the FORCE CPU boards is also controlled by the fga, and is enabled if the eeprom variable abort-ena? is set to true. Toggling the switch when enabled stops the kernel and starts the kernel debugger ddb(4).

IOCTLS
The fga device responds to the following ioctl(2) calls defined in <machine/fgaio.h>:

FGAIOCSEM
    (struct fga_sem) Clear (release) the semaphore fgasem_num. The argument structure is defined as follows:

        struct fga_sem {
                u_int8_t fgasem_num; /* semaphore number */
        	u_int8_t fgasem_val; /* semaphore value */
        };

FGAIOSSEM
    (struct fga_sem) Set (attempt to get) the semaphore fgasem_num. If successful, fgasem_val will have a value of 1, otherwise it will have a value of 0.

FGAIOCMBX
    (struct fga_sem) Clear (release) the mailbox fgasem_num.

FGAIOSMBX
    (struct fga_sem) Set (attempt to get) the mailbox fgasem_num. If successful, fgasem_val will have a value of 1, otherwise it will have a value of 0.

SEE ALSO
ioctl(2), ddb(4), intro(4), eeprom(8)

HISTORY
OpenBSD support for the fga first appeared in OpenBSD 2.6.

AUTHORS
The driver for the fga was written by Jason L. Wright <jason@thought.net> under contract with RTMX Incorporated.

BUGS
There are several features provided by the FGA5000 that are not implemented in the driver. Most notably, VME slave ranges are not mapped and the DMA engine is not used. Also, several VME interrupts are not handled: SYSFAIL and ACFAIL.