IOASIC(9)              NetBSD Kernel Developer's Manual              IOASIC(9)

NAME
     IOASIC, ioasic_intr_establish, ioasic_intr_disestablish,
     ioasic_intr_evcnt, ioasic_attach_devs, ioasic_submatch -- baseboard I/O
     control ASIC for DEC TURBOchannel systems

SYNOPSIS
     #include <machine/bus.h>
     #include <dev/tc/tcvar.h>
     #include <dev/tc/ioasicreg.h>
     #include <dev/tc/ioasicvar.h>

     void
     ioasic_intr_establish(struct device *dev, void *cookie, int level,
         int (*handler)(void *), void *arg);

     void
     ioasic_intr_disestablish(struct device *dev, void *cookie);

     const struct evcnt *
     ioasic_intr_evcnt(struct device *dev, void *cookie);

     void
     ioasic_attach_devs(struct ioasic_softc *sc,
         struct ioasic_dev *ioasic_devs, int ioasic_ndevs);

     int
     ioasic_submatch(struct cfdata *match, struct ioasicdev_attach_args *ia);

DESCRIPTION
     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-
     related conditions.

DATA TYPES
     Drivers for devices attached to the IOASIC will make use of the following
     data types:

     struct ioasicdev_attach_args
              A structure used to inform the driver of the IOASIC device prop-
              erties.  It contains the following members:

                      char                    iada_modname
                      tc_offset_t             iada_offset
                      tc_addr_t               iada_addr
                      void                    *iada_cookie;

     struct ioasic_softc
              The parent structure which contains at the following members
              which are useful for drivers:

                      bus_space_tag_t         sc_bst;
                      bus_space_handle_t      sc_bsh;
                      bus_dma_tag_t           sc_dmat;

     struct ioasic_dev
              A structure describing the machine-dependent devices attached to
              the IOASIC containing the following members:

                      char                    *iad_modname;
                      tc_offset_t             iad_offset;
                      void                    *iad_cookie;
                      uint32_t                iad_intrbits;

FUNCTIONS
     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.

     ioasic_intr_disestablish(dev, cookie)
              Dis-establish the interrupt handler with device dev for the
              interrupt described complete ly cookie.

     ioasic_intr_evcnt(dev, 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.

     ioasic_submatch(match, ia)
              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.

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.

DMA SUPPORT
     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.

CODE REFERENCES
     This section describes places within the NetBSD source tree where actual
     code implementing or using the machine-independent IOASIC subsystem can
     be found.  All pathnames are relative to /usr/src.

     The IOASIC subsystem itself is implemented within the file
     sys/dev/tc/ioasic_subr.c.  Machine-dependent portions can be found in
     sys/arch/<arch>/tc/ioasic.c.

SEE ALSO
     ioasic(4), autoconf(9), bus_dma(9), bus_space(9), driver(9)

NetBSD 5.0_STABLE               August 6, 2000               NetBSD 5.0_STABLE
