August 6, 2000 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

```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 sixteen 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 properties. 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 completed 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)