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IOASIC(9) NetBSD Kernel Developer's Manual IOASIC(9)
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IOASIC, ioasic_intr_establish, ioasic_intr_disestablish,
ioasic_intr_evcnt, ioasic_attach_devs, ioasic_submatch -- baseboard I/O
control ASIC for DEC TURBOchannel systems
ioasic_intr_establish(struct device *dev, void *cookie, int level,
int (*handler)(void *), void *arg);
ioasic_intr_disestablish(struct device *dev, void *cookie);
const struct evcnt *
ioasic_intr_evcnt(struct device *dev, void *cookie);
ioasic_attach_devs(struct ioasic_softc *sc,
struct ioasic_dev *ioasic_devs, int ioasic_ndevs);
ioasic_submatch(struct cfdata *match, struct ioasicdev_attach_args *ia);
The IOASIC device provides support for the DEC proprietary IOCTL ASIC
found on all DEC TURBOchannel machines with MIPS (DECstation 5000 series,
excluding the 5000/200) and Alpha (3000-series) systems. The IOASIC is
memory-mapped into the TURBOchannel system slot to interface up to six-
teen I/O devices. It connects the TURBOchannel to a 16-bit wide I/O bus
and supplies various control signals to the devices that share this bus.
The IOASIC provides hardware DMA channels and interrupt support. DMA
transfers are between one and four 32-bit words (16 bytes) in length,
depending on the device. The IOASIC stores the data in internal data
registers. The data is transferred to and from the registers in 16-bit
words to the device. Various interrupts are signalled on DMA pointer-
Drivers for devices attached to the IOASIC will make use of the following
A structure used to inform the driver of the IOASIC device prop-
erties. It contains the following members:
The parent structure which contains at the following members
which are useful for drivers:
A structure describing the machine-dependent devices attached to
the IOASIC containing the following members:
ioasic_intr_establish(dev, cookie, level, handler, arg)
Establish an interrupt handler with device dev for the interrupt
described completely by cookie. The priority of the interrupt
is specified by level. When the interrupt occurs the function
handler is called with argument arg.
Dis-establish the interrupt handler with device dev for the
interrupt described complete ly cookie.
Do interrupt event counting with device dev for the event
described completely by cookie.
ioasic_attach_devs(sc, ioasic_devs, ioasic_ndevs)
Configure each of the ioasic_ndevs devices in ioasic_devs.
Check that the device offset is not OASIC_OFFSET_UNKNOWN.
The ioasic_intr_establish(), ioasic_intr_disestablish(), and
ioasic_intr_evcnt() functions are likely to used by all IOASIC device
drivers. The ioasic_attach_devs() function is used by ioasic driver
internally and is of interest to driver writers because it must be aware
of your device for it to be found during autoconfiguration.
The IOASIC is a direct-connection bus. During autoconfiguration,
machine-dependent code will provide an array of struct ioasic_devs
describing devices attached to the IOASIC to be used by the ioasic
driver. The ioasic driver will pass this array to ioasic_attach_devs()
to attach the drivers with the devices.
Drivers match the device using iada_modname.
During attach, all drivers should use the parent's bus_space and bus_dma
resources, and map the appropriate bus_space region using
bus_space_subregion() with iada_offset.
No additional support is provided for IOASIC DMA beyond the facilities
provided by the bus_dma(9) interface.
The IOASIC provides two pairs of DMA address pointers (transmitting and
receiving) for each DMA-capable device. The pair of address pointers
point to consecutive (but not necessarily contiguous) DMA blocks of size
IOASIC_DMA_BLOCKSIZE. Upon successful transfer of the first block, DMA
continues to the next block and an interrupt is posted to signal an
address pointer update. DMA transfers are enabled and disabled by bits
inside the IOASIC status (CSR) register.
The interrupt handler must update the address pointers to point to the
next block in the DMA transfer. The address pointer update must be com-
pleted before the completion of the second DMA block, otherwise a DMA
overrun error condition will occur.
The IOASIC subsystem itself is implemented within the file
sys/dev/tc/ioasic_subr.c. Machine-dependent portions can be found in
ioasic(4), autoconf(9), bus_dma(9), bus_space(9), driver(9)
NetBSD 9.99 August 6, 2000 NetBSD 9.99