ARM CoreLink CCI-550 Cache Coherent Interconnect Technical Reference Manual : 3.3.10 Snoop Control Registers

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

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

Indicates whether the slave interface supports DVM messages.

0	The interface does not support DVM messages.
1	The 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.

Indicates whether the slave interface supports snoop requests.

0	The interface does not support snoops.
1	The 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.

Indicates whether the slave interface has a system coherency interface to provide hardware snoop enable control.

0	The interface does not have hardware snoop enable control. The settings in this register apply.
1	The interface has hardware snoop enable control. Writes to this register are ignored.

[28:2]

Reserved

[1]

enable_dvms

When the slave interface supports DVM messages, enables issuing of DVM message requests from this slave interface:

0	Disable DVM message requests.
1	Enable 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:

0	DVM requests are disabled.
1	DVM 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

When the slave interface supports snoops, enables issuing of snoop requests from this slave interface:

0	Disable snoop requests.
1	Enable 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:

0	Snoop requests are disabled.
1	Snoop 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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