Altera Arria V Avalon-ST - Manual (Page 80)

Figure 4-30: Local Management Interface
Configuration Space
128 32-bit registers
(4 KBytes)
LMI
32 lmi_dout
lmi_ack
15 lmi_addr
32 lmi_din
lmi_rden
lmi_wren
pld_clk
Hard IP for PCIe
The LMI interface is synchronized to
pld_clk
and runs at frequencies up to 250 MHz. The LMI address is
the same as the Configuration Space address. The read and write data are always 32 bits. The LMI
interface provides the same access to Configuration Space registers as Configuration TLP requests.
Register bits have the same attributes, (read only, read/write, and so on) for accesses from the LMI
interface and from Configuration TLP requests.
Note: You can also use the Configuration Space signals to read Configuration Space registers. For more
information, refer to Transaction Layer Configuration Space Signals.
When a LMI write has a timing conflict with configuration TLP access, the configuration TLP accesses
have higher priority. LMI writes are held and executed when configuration TLP accesses are no longer
pending. An acknowledge signal is sent back to the Application Layer when the execution is complete.
All LMI reads are also held and executed when no configuration TLP requests are pending. The LMI
interface supports two operations: local read and local write. The timing for these operations complies
with the Avalon-MM protocol described in the Avalon Interface Specifications. LMI reads can be issued at
any time to obtain the contents of any Configuration Space register. LMI write operations are not
recommended for use during normal operation. The Configuration Space registers are written by requests
received from the PCI Express link and there may be unintended consequences of conflicting updates
from the link and the LMI interface. LMI Write operations are provided for AER header logging, and
debugging purposes only.
• In Root Port mode, do not access the Configuration Space using TLPs and the LMI bus simultane‐
ously.
Table 4-16: LMI Interface
Signal Direction Description
lmi_dout[31:0] Output Data outputs.
2014.12.15
LMI Signals 4-43
Interfaces and Signal Descriptions Altera Corporation
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