cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 95

• Manufacturer Part Number: cx28560
• Description: Hdlc Controller
• Manufacturer: Mindspeed Technologies

CX28560 Data Sheet
5.2
5.2.1
Table 5-3. Service Request Length Register
28560-DSH-001-B
31:10
9:0
Bit
RSVD
SRQ_LEN[9:0]
Field Name
Global Registers
Service Request Mechanism
The registers that need to be configured and checked to enable the activity of the
service request mechanism are as follows:
The availability of the device is an example of information provided by querying the
Service Request Length register. After the PCI reset, the CX28560 sets the SRQ_LEN
bit field in Service Request register to all ones until it performs all the internal
initialization. When the CX28560 is finished with the internal initialization, it clears
this field to 0. The cleared SRQ_LEN provides to the host the information of the
CX28560’s readiness. From this point, the host is able to directly write this bit field
with the actual number of service requests that the CX28560 needs to perform to
configure its registers. The number of SRQs written by the host is stored in the
SRQ_LEN bit field. While processing the service request commands, the SRQ_LEN
field indicates how many commands are yet to be processed by the CX28560 before a
new command can be issued. Host slave writes to this register trigger the execution of
the service request list.
NOTE:
Value
• Service Request Length register (see
• Service Request Pointer register (see
—
0
Host slave writes to SRQ_LEN bit, while the previous list of service requests
has not been processed (i.e., SRQ_LEN is reset) implies unpredictable
behavior.
Reserved.
Service Request Length.
After a PCI reset, host reads the SRQ_LEN bit field through PCI slave access. While the
SRQ_LEN value equals all 1s, the CX28560 is not ready to start the configuration of the
device. If the CX28560 resets this value, the device is ready to be configured. Host
directly writes at this location the number of Service Request Descriptors (SRD) which
were allocated in Service Request Descriptor Table (SRDT) i.e., shared memory. The
SRDs used to be previously initialized and configured in SRDT. This value represents the
number of service request commands queued by host (i.e., the SRDT), that are waiting
to be performed. Real-time reads from SRQ_LEN provides the number of service
request commands that are waiting to be served.
Mindspeed Technologies™
Advance Information
Description
Table
Table
5-1)
5-1)
The CX28560 Memory Organization
5
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5