3.3.10 Snoop Control Registers

These registers control the issuing of snoop and DVM requests on slave interfaces.

You can read the register to determine whether the interface supports snoops or DVM messages. Enabling snoop or DVM requests on an interface that does not support them has no effect.
Usage constraints
Accessible using only Secure accesses, unless you set the Secure Access Register to permit Non-secure accesses.
Configurations
Available in all CCI-550 configurations.
An instance of this register exists for each slave interface.
Attributes
See 3.2 Register summary for more information.
The following figure shows the bit assignments.
Figure 3-8 snoop_ctrl register bit assignments
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The following table shows the bit assignments.

Table 3-11 snoop_ctrl register bit assignments

Bits
Name
Reset
Access
Function
[31]
support_dvms
ACCHANNELENSx[0] input
RO
Indicates whether the slave interface supports DVM messages.
0The interface does not support DVM messages.
1The interface supports DVM messages.
This bit is overridden to 0 if you set the Control Override Register bit[1].
[30]
support_snoops
ACCHANNELENSx[1] input for ACE interfaces.
This bit is set to 0 for ACE-Lite interfaces.
RO
Indicates whether the slave interface supports snoop requests.
0The interface does not support snoops.
1The interface supports snoops.
This bit is overridden to 0 if you set the Control Override Register bit[0].

Note

This bit only affects the operation of ACE interfaces.
[29]
hardware_snoop_enable_control
IMPLEMENTATION DEFINED.
RO
Indicates whether the slave interface has a system coherency interface to provide hardware snoop enable control.
0The interface does not have hardware snoop enable control. The settings in this register apply.
1The interface has hardware snoop enable control. Writes to this register are ignored.
[28:2]
Reserved
-
-
-
[1]
enable_dvms
0
RW
When the slave interface supports DVM messages, enables issuing of DVM message requests from this slave interface:
0Disable DVM message requests.
1Enable DVM message requests.
This bit is RAZ/WI for interfaces that do not support DVM messages.
If bit[29] is set to 1, indicating that hardware snoop control is enabled, this bit indicates whether DVM message requests are enabled for this interface:
0DVM requests are disabled.
1DVM requests are enabled.

Note

This bit is writable only when bit[31] is set to 1 and bit[29] is set to 0.
[0]
enable_snoops
0
RW
When the slave interface supports snoops, enables issuing of snoop requests from this slave interface:
0Disable snoop requests.
1Enable snoop requests.
This bit is RAZ/WI for interfaces that do not support snoops.
If bit[29] is set to 1, indicating that hardware snoop control is enabled, this bit indicates whether snoop requests are enabled for this interface:
0Snoop requests are disabled.
1Snoop requests are enabled.

Note

  • This bit only affects the operation of ACE interfaces.
  • This bit is writable only when bit[30] is set to 1 and bit[29] is set to 0.
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