8201, 8202, 8203, 8204 Acceleration Processor Data Sheet, DS-0157-05
Page 134
Exar Confidential
Subsystem and Vendor ID
The host reads the subsystem and vendor ID from the 820x device during initialization. The
value that the 820x responds with depends on the setting of the pin EXT_FLASH_CFG_EN.
If EXT_FLASH_CFG_EN is disabled, the 820x will respond with the Exar subsystem and
Register”). If EXT_FLASH_CFG_EN is enabled, the 820x will respond with the subsystem
and vendor ID values that are stored in the programmable device, thus allowing custom
applications to respond with their own subsystem and vendor ID values.
PHY Settings
The 820x device configures the PHY during initialization. The values that the 820x uses to
configure the PHY depend on the setting of the pins PCIE_PHY_CFG and
EXT_FLASH_CFG_EN. If PCIE_PHY_CFG is disabled, the 820x will configure the PHY using
the values set on the pins PCIE_RXEQCTL[2:0], PCIE_LOS_LVL[4:0], PCIE_TX_BOOST[3:0]
and PCIE_TX_LVL[4:0]. If PCIE_PHY_CFG is enabled and EXT_FLASH_CFG_EN is disabled,
the 820x will configure the PHY using the default internal register values. If PCIE_PHY_CFG
is enabled and EXT_FLASH_CFG_EN is also enabled, the 820x will respond with the PHY
values that are stored in the programmable device.
When programming the PHY settings into the programmable device, it is important to pay
attention to the endian positions of these values.
Expansion ROM BAR
The Expansion ROM BAR is used by the host to directly access the programmable device
attached to the 820x. The host reads the expansion ROM BAR value from the 820x device
during initialization. The value that the 820x responds with depends on the setting of the
Table 5-2. Programmable Device Memory Map
Byte Offset Byte 3
Byte 2
Byte 1
Byte 0
0x00
Subsystem ID
Vendor ID
0x04
[15:4] = PCIE_RXEQCTL[11:0]
[3:0] = 4’b0000
[15:0] = PCIE_TX_BOOST[15:0]
0x08
[7:0] = 8’h00
[7:5] = 3'b000
[4:0] =
PCIE_LOS_LVL
[4:0]
[7:5] = 3'b000
[4:0] =
PCIE_TX_LVL[4:0]
Reserved
0x0C
Expansion ROM BAR
Bits 31:1 Expansion ROM BAR Mask
Indicates which Expansion ROM BAR bits to mask (make non-writable) from host
software, which, in turn, determines the size of the BAR.
For example, 0xFFF claims a 4096-byte BAR by masking bits 11:0 of the BAR
from writing by host software.The maximum value is 0xFFFFFF because the
maximum space that can be claimed by an Expansion ROM BAR is 16 MB.
Bit 0 Expansion ROM BAR enable
0 = Expansion ROM BAR disabled
1 = Expansion ROM BAR enabled