7.4. Pause/PFC Flow Control Registers
| Addr | Bit | Name | Description | Reset | Access | 
|---|---|---|---|---|---|
| 0x600 | 31:0 | TX Flow Control Revision ID |   Specifies the revision ID, "25GEFCTx CSR".  |  
         0x0916_2016  |  
       RO | 
| 0x601 | 31:0 | TX Flow Control Scratch Pad | Scratch register for testing. | 0 | RW | 
| 0x602 | 31:0 | TX Flow Control IP Core Variant 0 |   Specifies first 4 characters of IP core variation identifier ASCII string, "25GE ".  |  
         0x3235_4745  |  
       RO | 
| 0x603 | 31:0 | TX Flow Control IP Core Variant 1 | Next 4 characters of IP core variation identifier ASCII string, "FCTx". | 0x4643_5478 | RO | 
| 0x604 | 31:0 | TX Flow Control IP Core Variant 2 |   Final 4 characters of IP core variation identifier ASCII string, "0CSR". The "0" is unprintable.  |  
       0x0043_5352 | RO | 
| 0x605 |   (FCQN-1):0  |  
         TX Flow Control Enable  |  
       Enables the IP core to generate XON and XOFF Pause/PFC flow control frames to the remote partner. The following encodings are defined: 
        
 You can change this field dynamically.  |  
         1'b1 in each bit that corresponds to a queue  |  
       RW | 
|   31:FCQN  |  
       Reserved | Reserved | 0 | RO | |
| 0x606 |   (FCQN-1):0  |  
         TX Flow Control CSR XON/XOFF Request 1 One bit per queue  |  
       XON/XOF flow control frame request bit 0. Interpretation depends on whether the IP core is in 1-bit FC request mode or in 2-bit FC request mode. This register affects a flow control queue only if the corresponding bit of the TX Flow Control Enable register has the value of 1.  In 2-bit mode, in addition, this register is active for a specific flow control queue only if the corresponding bit in the TX 2-bit Flow Control Request Mode register field (bits [(FCQN-1):0] of the register at offset 0x641) specifies that the flow control logic accepts input from this register. The following encodings are defined for 1-bit mode. The IP core reads the 1-bit mode value in TX Flow Control CSR XON/XOFF Request 0. 
 The following encodings are defined for 2-bit mode. The IP core reads the 2-bit mode value in {TX Flow Control CSR XON/XOFF Request 1, TX Flow Control CSR XON/XOFF Request 1}. 
 You can modify the value of this field dynamically.  |  
       0 | RW | 
|   15:FCQN  |  
       Reserved | Reserved | 0 | RO | |
|   (FCQN+15):16  |  
         TX Flow Control CSR XON/XOFF Request 1 1-bit per queue  |  
         In conjunction with Flow Control XON/XOFF Request 0 specifies a 2-bit request for XON/XOFF flow control frame transmission. This bit is the upper bit of the 2-bit control field. You can change the value of this field dynamically.  |  
       0 | RW | |
|   31:(FCQN+16)  |  
       Reserved | Reserved | 0 | RO | |
| 0x607 | 31:0 | Reserved | Reserved | N/A | RO | 
| 0x608 | 31:0 | Reserved | Reserved | N/A | RO | 
| 0x609 | 31:0 | Reserved | Reserved | N/A | RO | 
| 0x60A | 0 |   TX Pause Enable 1-bit  |  
         Determines whether receiving a valid Pause frame stops TX user data transmission. 1'b0: Transmission is not stopped 1'b1: Transmission stops You cannot change the value of this field dynamically.  |  
       0 | RW | 
| 31:1 | Reserved | Reserved | 0 | RO | |
| 0x60B | 31:0 | Reserved | Reserved | N/A | RO | 
| 0x60C | 31:0 | Reserved | Reserved | N/A | RO | 
| 0x60D | 31:0 | TX Flow Control Destination Address Lower |   Specifies the 48-bit Destination Address of the flow control frame. Contains the 32 LSB of the address field. You cannot modify the value of this field dynamically.  |  
       0xC2000001 | RW | 
| 0x60E | 15:0 | TX Flow Control Destination Address Upper |   Specifies the 48-bit Destination Address of flow control frame. Contains the 16 MSB of the address field. You cannot modify the value of this field dynamically.  |  
       0x0180 | RW | 
| 31:16 | Reserved | Reserved | 0 | RO | |
| 0x60F | 31:0 | TX Flow Control Source Address Lower |   Specifies the 48-bit Source Address of flow control frame. Contains the 32 LSB of the address field.  |  
       0xCBFC5ADD | RW | 
| 0x610 | 15:0 | TX Flow Control Source Address Upper |   Specifies the 48-bit Source Address of flow control frame. Contains the 16 MSB of the address field. You cannot modify the value of this field dynamically.  |  
       0xE100 | RW | 
| 31:16 | Reserved | Reserved | 0 | RO | |
|   0x620, 0x621, …, 0x620+(FCQN-1 )  |  
       15:0 |   TX Flow Control Quanta 16-bit per queue  |  
         Specifies the pause quanta of Pause/PFC flow control frames to be sent to remote partner. You cannot modify the value of this field dynamically.  |  
       0xFFFF | RW | 
| 31:16 | Reserved | Reserved | 0 | RO | |
| 0x628, 0x629, …, 0x628+(FCQN-1 ) | 15:0 |   TX Flow Control Signal XOFF Request Hold Quanta 16-bit per queue  |  
         Specifies the separation between 2 consecutive XOFF flow control frames. You cannot modify the value of this field dynamically.  |  
       0xFFFF | RW | 
| 31:16 | Reserved | Reserved | 0 | RO | |
| 0x640 | 0 |   TX Flow Control Select 1-bit  |  
         Specifies whether the TX hardware generates Pause or PFC frames. Affects only PFC Queue 0. Usage example: You can synthesize a single PFC queue and use it for both Pause and PFC purpose. 1'b0: Pause 1'b1: PFC You cannot modify the value of this field dynamically.  |  
       1 | RW | 
| 31:1 | Reserved. | Reserved. | 0 | RO | |
| 0x641 | (FCQN-1):0 |   TX 2-bit Flow Control Request Mode 1-bit per queue  |  
         Determines whether the TX Flow Control CSR XON/XOFF Request register or the pause_insert_tx0 and pause_insert_tx1 signals control XON/XOFF mode in 2-bit control mode. 1'b0: The pause_insert_tx0 and pause_insert_tx1 signals control requests 1'b1: The TX Flow Control CSR XON/XOFF Request register fields control requests You cannot modify the value of this field dynamically.  |  
       0 | RW | 
| 16 |   TX Flow Control Request Mode 1 bit for all queues  |  
         Determines whether the IP core is in TX flow control 1-bit mode or 2-bit mode. 1'b0: Use 1-bit mode to make TX flow control requests 1'b1: Use 2-bit mode to make TX flow control requests  |  
       0 | RW | |
| 31:17 | Reserved | Reserved | 0 | RO | 
| Addr | Bit | Name | Description | Reset | Access | 
|---|---|---|---|---|---|
| 0x700 | 31:0 | RX Flow Control Revision ID |   Provides the flow control revision, "25GEFCRx CSR".  |  
       0x0916_2016 | RO | 
| 0x701 | 31:0 | RX Flow Control Scratch Pad | Provides a register for debug. | 0 | RW | 
| 0x702 | 31:0 | RX Flow Control IP Core Variant 0 |   First 4 characters of IP core variation identifier ASCII string, "25GE".  |  
         0x3235_4745  |  
       RO | 
| 0x703 | 31:0 | RX Flow Control IP Core Variant 1 | Next 4 characters of IP core variation identifier ASCII string, "FCRx". | 0x4643_5278 | RO | 
| 0x704 | 31:0 | RX Flow Control IP Core Variant 2 | Final 4 characters of IP core variation identifier ASCII string, "0CSR". The "0" is unprintable. | 0x0043_5352 | RO | 
| 0x705 | (FCQN-1):0] |   RX PFC Enable 1 bit per queue  |  
         Determines whether receiving a valid PFC frame causes the PFC duration user interface to indicate a valid pause quanta duration to the user logic. 1'b0: Disable 1'b1: Enable You cannot modify the value of this field dynamically.  |  
       1'b1 in each bit that corresponds to a queue | RW | 
| 31:FCQN 8 | Reserved | Reserved | 0 | RO | |
| 0x706 | 31:0 | Reserved | Reserved | N/A | RO | 
| 0x707 | 31:0 | RX Flow Control Destination Address Lower |   Specifies the 48-bit Destination Address of the flow control frame. Contains the 32 LSB of the address field. You cannot modify the value of this field dynamically.  |  
       0xC2000001 | RW | 
| 0x708 | 15:0 | RX Flow Control Destination Address Upper |   Specifies the 48-bit Destination Address of flow control frame. Contains the 16 MSB of the address field. You cannot modify the value of this field dynamically.  |  
       0x0180 | RW | 
| 31:16 | Reserved | Reserved | 0 | RO |