cx28500 Mindspeed Technologies, cx28500 Datasheet - Page 89

• Manufacturer Part Number: cx28500
• Description: Cx28500 Multichannel Synchronous Communications Controller
• Manufacturer: Mindspeed Technologies

A list of service request commands is defined as a sequence of SRDs. The following instructions, referred to in the
document as OPCODE, are supported:
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•
•
•
•
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Table 6-5
A service request is issued to a specific channel, or per whole device. Each service request command is
acknowledged by sending a service request acknowledge interrupt descriptor back to the Host if the SACKIEN bit
is enabled in SRD. It is possible for the Host to issue multiple service requests successively without expecting or
receiving acknowledgments from each request if the SACKIEN bit was not set accordingly in the SRD.
Host can only set the SACKIEN bit in the last SRD so if a SACK Service Request Acknowledge interrupt is
received, it validates the whole list of service request commands.
Activate, Deactivate, or Jump commands could take a long time before they are actually executed by CX28500.
CX28500 returns the SACK (if SACKIEN bit is set) immediately after it started the command execution. Therefore,
the Host may not assume the command was actually executed just by detecting the SACK was returned. Another
interrupt, End Of Command Execution (EOCE), is defined for each of these three commands. The Host may
assume the command was actually executed only after receiving the appropriate EOCE.
In general, SACK is only issued after each service table entry is completed. However, for Activate, Deactivate, and
Jump commands, SACKs are issued after SLP is completed, but before DMA completes (see End of Command
interrupt).
Table 6-5.
28500-DSH-002-C
CONFIG_WR
CONFIG_RD
OPCODE
Configure a port/channel
Read specific descriptors
Activate or reactivate a channel
Deactivate a channel
Jump to new Buffer Descriptor table
No-operation command
Perform EBUS access (read or write)
NOP
defines the Service Request Descriptor OPCODE.
Service Request Descriptor—OPCODE Description (1 of 2)
Value
0h
1h
2h
No Operation.
This service request performs no action other than to facilitate a Host Service Acknowledge Interrupt (SACK). This
would be used as a UNIX ping-like operation to detect the presence of CX28500.
Configuration Write.
This is a request to copy from shared memory data into CX28500’s internal registers. This service request can be
issued for either one register or for the whole CX28500 register map (up to 16 K-1 registers), depending on the
value of LENGTH bit field set in Service Request Descriptor.
Note that the Service Request Descriptor used for this command is Device Configuration Descriptor. The LENGTH bit
value in this descriptor is up to 16 K. Assuming that the Host configures an 16 K register structure in shared
memory and the LENGTH bit field is set accordingly, CX28500 configures the entire configuration in one service
request command in bursts of 32 dwords (i.e., the maximum allowed PCI burst).
Configuration Read.
This is a request to copy the configuration of CX28500’s internal registers into shared memory. The configuration
located at the address specified by the CX28500 register Map Base Address Offset is read and copied to the address
specified by the shared memory address. The number of dwords copied is specified in the LENGTH bit field. The
user needs to instruct CX28500 to perform the correct number of reads so that when data is written in shared
memory, no data overlapping occurs. The Service Request Descriptor used for this command is Device
Configuration Descriptor.
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Memory Organization
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