VSC7440 datasheet(74/444 Pages) MICROSEMI

74 / 444 page

Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

To disable a rule, one or more bits in the entry is set to match-off. VCAP ES0 does not allow match-off

encoding. Rules are instead enabled and disabled by the VCAP_RULE_ENA.RULE_ENA cache field.

The counter for a rule is incremented when the entry of the rule is matched by a key. Counters that are 1-

bit wide do not wrap, but instead saturate at 1.

3.12.1.1 Writing, Reading, and Initializing Rules

All access to and from VCAP memory goes through the cache.

To write a rule in the VCAP memory at address a: Entry data, entry action, and counter is first written to

the cache registers and then transferred into VCAP memory by triggering a write operation on the cache

by setting VCAP_UPDATE_CTRL.UPDATE_CMD = 0, VCAP_UPDATE_CTRL.UPDATE_ADDR = a,

and VCAP_UPDATE_CTRL.UPDATE_SHOT = 1. The UPDATE_SHOT field is cleared by hardware

when the rule has put into VCAP memory.

To read a rule from address a in the VCAP memory: Trigger a read operation on the cache by setting

VCAP_UPDATE_CTRL.UPDATE_CMD = 1, VCAP_UPDATE_CTRL.UPDATE_ADDR = a, and

VCAP_UPDATA_CTRL.UPDATE_SHOT = 1. The UPDATE_SHOT field is cleared by hardware when a

copy of the rule is available for reading via cache registers.

Active rules must not be overwritten by other rules (except when writing disabled rules). Software must

make sure that addresses are initialized before they are written.

It is possible to write the contents of the cache can be written to a range of addresses inside VCAP

memory. This is used during initialization of VCAP memory.

To write the contents of the cache to addresses a through b in VCAP memory, where a < b: Trigger an

initialization-operation by setting VCAP_MV_CFG.MV_NUM_POS = b-a. And

VCAP_UPDATE_CTRL.UPDATE_CMD = 4, VCAP_UPDATE_CTRL.UPDATE_ADDR = a, and

VCAP_UPDATE_CTRL.UPDATA_SHOT = 1. When the UPDATE_SHOT field is cleared, the addresses

have been overwritten with the contents of the cache.

The cache can be cleared by writing VCAP_UPDATE_CTRL.CLEAR_CACHE = 1. This immediately sets

the contents of the entry to disabled, action and counter is set to all-zeros.

VCAP_UPDATE_CTRL.CLEAR_CACHE can be set at the same time as triggering an write or

initialization operation, the cache will be cleared before writing to the VCAP memory.

It is possible to selectively disable access to entry, action, and/or counter during operations by setting

VCAP_UPDATE_CTRL.UPDATE_ENTRY_DIS, VCAP_UPDATE_CTRL.UPDATE_ACTION_DIS, or

VCAP_UPDATE_CTRL.UPDATE_CNT_DIS. These fields allow specialized operations such as clearing

counter values by performing initialization or write operations with disabled entry and action updating.

3.12.1.2 Moving a Block of Rules

The VCAP supports move operation for efficient and safe moving of rules inside VCAP memory. Moving

may be required to make room for new rules, because rules are prioritized by address.

To move n addresses from address a to address b in VCAP memory: Trigger a move operation by setting

VCAP_MV_CFG.MV_NUM_POS = (a>b ? a-b : b-a), VCAP_MV_CFG.MV_SIZE = (n-1). And setting

VCAP_UPDATE_CTRL.UPDATE_CMD = (a>b ? 2 : 3), VCAP_UPDATE_CTRL.UPDATE_ADDR = a,

and VCAP_UPDATE_CTRL.UPDATE_SHOT = 1. When the UPDATE_SHOT field is cleared, the

contents of the addresses have been moved inside VCAP memory. The cache is overwritten during the

move-operation.

Rules must not be moved to a region that contains active rules. Software must make sure that

destination addresses are initialized before performing a move operation. After moving rules the move

operation leaves VCAP memory in initialized state, so overlapping source and destination regions is not

a problem during move operations.

3.12.1.3 Sharing Resources

The device implements a shared pool of six blocks that can be distributed freely among the CLM, IS2,

and LPM VCAPs. Each block in the pool has 1,024 addresses with entries, actions, and counters.

VSC7440 датащи(PDF) 74 Page - Microsemi Corporation

VSC7440 датащи(HTML) 74 Page - Microsemi Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL