82598EB Datasheet, PDF (390/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - Register Descriptions
FW_PHY_SM1
FW_MAC_CSR_SM
Reserved
7
When set to 1b, PHY 1 access is owned by firmware
8
When set to 1b, firmware owns access to shared CSRs
9
Reserved for future firmware use
When software or firmware gains control over the GSSR, it checks if a certain resource is owned by the
other (the bit is set). If not, it might set its bits for that resource, taking ownership of the resource. The
same process (claiming the semaphore and accessing the GSSR) is done when a resource is being
freed.
The following example shows how software might use this mechanism to own a resource (firmware
accesses are done in an analogous manner):
1. Software takes control over the software/firmware semaphore.
a. Software writes a 1b to the SWESMBI bit in the SWSM.
b. Software reads the SWESMBI bit. If set, software owns the semaphore. If cleared, this is an
indication that firmware currently owns the semaphore. Software should retry the previous step
after some delay.
2. Software reads the GSSR and checks the firmware bit in the pair of bits that control the resource is
wishes to own.
a. If the bit is cleared (firmware does not own the resource), software sets the software bit in the
pair of bits that control the resource is wishes to own.
b. If the bit is set (firmware owns the resource), go to step 4.
3. Software releases the software/firmware semaphore by clearing the SWESMBI bit in the SWSM.
4. If software did not succeed in owning the resource (from step 2b), software repeats the process
after some delay.
The following example shows how software might use this mechanism to release a resource (firmware
accesses are done in an analogous manner):
1. Software takes control over the software/firmware semaphore.
a. Software writes a 1b to the SWESMBI bit in the SWSM.
b. Software then reads the SWESMBI bit. If set, software owns the semaphore. If cleared, this is
an indication that firmware currently owns the semaphore. Software should retry the previous
step after some delay.
2. Software writes a 0b to the software bit in the pair of bits that control the resource is wishes to
release in the GSSR.
3. Software releases the software/firmware semaphore by clearing the SWESMBI bit in the SWSM.
4. Software waits some delay before trying to gain the semaphore again.
The following are time periods used by firmware.
Description
Time to backoff from a failed attempt to get the software/firmware semaphore to the next attempt.
Time
5 ms
390