Chapter 3. Using the Z85230 driver
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## Chapter 3. Using the Z85230 driver

The Z85230 driver provides the back end interface to your board. To configure a Z8530 interface you need to detect the board and to identify its ports and interrupt resources. It is also your problem to verify the resources are available.

Having identified the chip you need to fill in a struct z8530_dev, which describes each chip. This object must exist until you finally shutdown the board. Firstly zero the active field. This ensures nothing goes off without you intending it. The irq field should be set to the interrupt number of the chip. (Each chip has a single interrupt source rather than each channel). You are responsible for allocating the interrupt line. The interrupt handler should be set to `z8530_interrupt`. The device id should be set to the z8530_dev structure pointer. Whether the interrupt can be shared or not is board dependent, and up to you to initialise.

The structure holds two channel structures. Initialise chanA.ctrlio and chanA.dataio with the address of the control and data ports. You can or this with Z8530_PORT_SLEEP to indicate your interface needs the 5uS delay for chip settling done in software. The PORT_SLEEP option is architecture specific. Other flags may become available on future platforms, eg for MMIO. Initialise the chanA.irqs to &z8530_nop to start the chip up as disabled and discarding interrupt events. This ensures that stray interrupts will be mopped up and not hang the bus. Set chanA.dev to point to the device structure itself. The private and name field you may use as you wish. The private field is unused by the Z85230 layer. The name is used for error reporting and it may thus make sense to make it match the network name.

Repeat the same operation with the B channel if your chip has both channels wired to something useful. This isn't always the case. If it is not wired then the I/O values do not matter, but you must initialise chanB.dev.

If your board has DMA facilities then initialise the txdma and rxdma fields for the relevant channels. You must also allocate the ISA DMA channels and do any necessary board level initialisation to configure them. The low level driver will do the Z8530 and DMA controller programming but not board specific magic.

Having initialised the device you can then call `z8530_init`. This will probe the chip and reset it into a known state. An identification sequence is then run to identify the chip type. If the checks fail to pass the function returns a non zero error code. Typically this indicates that the port given is not valid. After this call the type field of the z8530_dev structure is initialised to either Z8530, Z85C30 or Z85230 according to the chip found.

Once you have called z8530_init you can also make use of the utility function `z8530_describe`. This provides a consistent reporting format for the Z8530 devices, and allows all the drivers to provide consistent reporting.

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