Miscellaneous Control Registers
BCM5718 Programmer’s Guide
Broadcom
®
January 29, 2016 • 5718-PG108-R
Page 482
EAV Ref Count Capture LSB Reg (offset: 0x6900)
The MSB and LSB registers are interface to the actual EAV Ref Counter hardware. The Counter value may be
read via this pair anytime and even be overwritten by this pair anytime. While reading the pair, the hardware
Counter does not stop, only its value is latched in this pair.
The only two legal sequences of accessing this pair is Read-LSB followed by Read-MSB and Write-LSB
followed by Write-MSB.
EAV Ref Count Capture MSB Reg (offset: 0x6904)
EAV Ref Clock Control Reg (offset: 0x6908)
This register controls the EAV Reference Counter and the TimeSync related GPIO pins. Each MAC’s 1588
hardware owns a dedicated TimeSync_GPIO pin which may be connected to any of its four Snap-shot/
WatchDog hardware logic. If a MAC needs to use more pins beyond its TimeSync_GPIO pin, it may use any or
all of the four APE_GPIO[3:0] pins. Note that these pins are shared among APE hardware and four MAC-1588
hardware. Therefore, a platform must design-in these pins and have individual BootCode or firmware configure
this register and APE-GPIO register accordingly.
Name
Bits
Access
Default
Value
Description
EAV Reference Count
[lower half]
31:3
RW
UUUU
LSB of the EAV Reference Count–Reading this
LSB latches a Count in this pair until the time the
corresponding MSB is read.
Writing to this LSB latches the value in this pair and
the subsequent write to the MSB transfers the 64-
bit value to EAV Ref Counter and counting
immediately resumes from there.
Reserved
2:0
RO
000
[2:0] shall always be 000
Name
Bits
Access
Default
Value
Description
EAV Reference Count
[Upper half]
31:0
RW
UUUU
MSB of the EAV Reference Count–See the pairing
LSB register.
Reading this register returns the MSB of the 64-bit
EAV Ref count previously latched by performing an
LSB read.
Writing to this MSB transfers the 64-bit value, this
plus previously latched LSB, to EAV Ref Counter
and counting immediately resumes from there.
Back to back writes to this MSB has no effect.
Note:
Hardware behavior shall be indeterminate in case of conflicting or duplicate assignment of GPIO
pins to the same resource. A platform MUST allocate its dedicated TimeSync_GPIO pin first before
using any pin from APE_GPIO shared pool.