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FGA(4) Device Drivers Manual (sparc) FGA(4)

fga, fvmeSPARC Force FGA5000 VME/SBus bridge driver

fga0 at iommu0
fvme* at fga0

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:

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).

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

(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 */
(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.
(struct fga_sem) Clear (release) the mailbox fgasem_num.
(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.

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

OpenBSD support for the fga first appeared in OpenBSD 2.6.

The driver for the fga was written by Jason L. Wright <> under contract with RTMX Incorporated.

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.

November 21, 2015 OpenBSD-6.0