BCM5722 Programmer’s Guide
10/15/07
Broadcom Corporation
Page 165 Wake on LAN Mode/Low-Power Document 5722-PG101-R
Firmware Mailbox
When the BCM5722 Ethernet controller initializes (the firmware bootcode is loaded from NVRAM when the chip powers on
or when reset completes), the bootcode checks the T3_FIRMWARE_MAILBOX in shared memory. When the
T3_MAGIC_NUM signature (0x4B657654) is present, the bootcode does not issue a hard reset to the PHY. This is especially
important in WOL mode since the PHY should not be reset.
Before the host software issues a reset to the BCM5722 Ethernet controller, it must write the T3_MAGIC_NUM to the shared
memory address T3_FIRMWARE_MAILBOX (0xb50). This address is a software mailbox, which bootcode polls before it
resets the PHY. The bootcode will acknowledge the signature by writing the one’s complement of the T3_MAGIC_NUM back
into the T3_FIRMWARE_MAILBOX. If the T3_MAGIC_NUM is present, the bootcode will not reset the PHY. After resetting
the BCM5722 Ethernet controller, host software should poll for the one’s complement of the T3_MAGIC_NUM before it
proceeds, otherwise, bootcode initialization may interfere with the host software initialization.
If the host software will be controlling the WOL configuration, it should write the DRV_WOL_SIGNATURE (0x474c0000) to
the shared memory address DRV_WOL_MAILBOX (0xd30) so that the bootcode will not take over the WOL initialization. If
the DRV_WOL_SIGNATURE is not present, and WOL has been enabled, the bootcode will assume that the host software
is a legacy driver and skip the WOL initialization. If WOL is disabled, the bootcode will take over the WOL initialization based
on the NVRAM configuration.
PHY Auto-Negotiation
The integrated PHY should be configured to auto-negotiate for a 10 Mbps connection (see Table 80). This step is required
if the NIC needs to be placed into a D3 cold state. Half- or full-duplex operation is acceptable. Software must modify auto-
advertise configurations in the PHY’s MDI registers. The link partner will read advertisement settings to find a highest com-
mon capability. Since WOL requires 10 Mbps wire speed, the two PHYs will effectively auto-negotiate for half- or full-duplex
connection.
Table 79: Firmware Mailbox Initialization
Name Address Recommended Value
T3_FIRMWARE_MAILBOX 0x0B50 0x4B657654
DRV_WOL_MAILBOX 0xd30 0x474c0000
Table 80: Recommended Settings for PHY Auto-Negotiation
Register Bit Recommended Value
Auto_Negotation_Advertisement 10_BASE_TX_Half_Duplex Enable
Auto_Negotation_Advertisement 10_BASE_TX_Full_Duplex Enable
Auto_Negotation_Advertisement 100_BASE_TX_Half_Duplex Disable
Auto_Negotation_Advertisement 100_BASE_TX_Full_Duplex Disable
1000BASE-T_Control 1000_BASE_TX_Half_Duplex Disable
1000BASE-T_Control 1000_BASE_TX_Full_Duplex Disable
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