TI380PCI Datasheet, PDF (27/36 Pages) Texas Instruments – PCI BUS INTERFACE FOR THE TI380 COMMPROCESSORS

TI380PCI
PCI BUS INTERFACE FOR THE TI380 COMMPROCESSORS
SPWS020 – AUGUST 1995
380PCI interface control register—configuration space DWORD address (0x54) (continued)
Typically, in personal computer (PC) systems the TI380PCI automatic software reset bit is set to a default value
of zero. In a PC system, when a CTRL-ALT-DEL is issued from the keyboard, the PCI bus does not receive a
reset. A TI380PCI bus master in the middle of a DMA transaction when the CTRL-ALT-DEL is issued can be
left in an unknown state. In this condition, the bus master could perform unexpected memory accesses to the
host after the TI380PCI device is enabled by the PCI BIOS during the boot process.
To eliminate this problem, the automatic software reset bit should be left set to the default value of zero. The
action of clearing the bus master bit in the TI380PCI control register (which is a direct consequence of issuing
the CTRL-ALT-DEL) also automatically resets the TI380PCI and clears any pending DMA transactions. The
reset induced by clearing the TI380PCI bus master bit is the same as the software reset that takes place when
bit 31 of the TI380PCI MISCCNTRL register is set to a one.
Bits 17 – 31: Reserved may not read as zero.
TI380C2x interface configuration register (TI2000)
The TI380PCI contains the following register which is defined in I / O space.
This is a READ ONLY register with the following functions:
CONFIG bit 15: The most significant bit of the configuration register, when set, indicates the existence of the
configuration register. This bit is hardwired to 1, to indicate the presence of a configuration register.
CONFIG=1 There is a configuration register.
CONFIG=0 There is no configuration register.
RESERVED bits 13 – 14: These bits must read as 0.
DEDMACTL bit 12: The Don’t Enable ISA DMA Controller (DEDMACTL) bit indicates whether the TI2000 driver
must enable the ISA DMA controller. The ISA DMA controller is not used to control operations on the PCI bus.
In order to allow the TI2000 software specification to be expanded to comprehend the PCI bus, this bit is
hardwired to a 1 to indicate that a TI2000 driver controlling a PCI-based network interface card should not enable
an ISA DMA controller. (The setting of this bit does not affect DMA on the PCI bus.)
DMA MODE
DMA
DMA
PDMA
DEDMACTL BIT VALUE
1 = Driver must NOT enable ISA DMA controller
0 = Driver must enable ISA DMA controller
x = Driver must NOT enable ISA DMA controller
INST8 bit 11: This bit indicates whether the driver can use 16-bit instructions to access the adapter registers.
This bit is hardwired to 0 because PCI-based machines are able to perform 16-bit instructions.
1 = The TI2000 driver must use 8-bit instructions to access the LAN adapter registers.
0 = The TI2000 driver can use 16-bit instructions to access the LAN adapter registers.
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