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STP2002QFP
Sun Microelectronics
Fast Ethernet, Parallel Port, SCSI (FEPS) - STP2002QFP
This bit is set to indicate that FAS366 has asserted its interrupt signal. Once
FAS366 asserts its interrupt signal, all the bytes in prefetch buffers are
drained to the host memory, before setting this bit or generating an interrupt
on SBus. Draining of buffers, before posting the interrupt to device driver,
saves PIOs. This bit will also be set during DMA loop-back. This bit will also
be set when the D_ERR_PEND bit is set.
D_ERR_PEND:
This bit is set in response to an Error ACK, during DVMA. This bit is reset
on setting D_RESET. This bit will also be set, when a parity error or a late
error is detected.
D_DRAINING:
When the buffers are draining to memory, this bit is set. DO NOT assert
D_RESET or write to D_ADDR register when set. This bit is not valid while
D_ERR_PEND is set and should be ignored.
D_RESET:
This bit will remain active once set to 1, until set to 0 or is cleared by a hard-
ware reset. Setting D_RESET or asserting hardware reset will invalidate the
prefetch buffers, reset all of the state machines to their idle states.
Note: This bit must be asserted at the end of each DMA transfer. In
other words, whenever D_ADDR and D_BCNT are programmed with
a new value, D_RESET should have been asserted prior to this
programming.
D_REQ_PEND: This bit is set when a DVMA read or write request is pend-
ing. Do not assert D_RESET when D_REQ_PEND or/and D_DRAINING
bit(s) is (are) set.
D_DSBL_ESP_DRN: If set, draining will not be forced when the CPU
makes a slave access to the FAS366, while SCSI DVMA is in progress. This
bit could be useful in block-mode operation, where FAS366 does not generate
interrupts on successful execution of commands. In such a case, device driv-
ers can use this bit to prevent forced draining, when making a slave access to
the FAS366 to monitor status.
7.3.2 SCSI Address Register
This register indicates the starting address from which DMA transfer takes