| Cadence IP BRA support |
| ---------------------- |
| |
| Format requirements |
| ~~~~~~~~~~~~~~~~~~~ |
| |
| The Cadence IP relies on PDI0 for TX and PDI1 for RX. The data needs |
| to be formatted with the following conventions: |
| |
| (1) all Data is stored in bits 15..0 of the 32-bit PDI FIFOs. |
| |
| (2) the start of packet is BIT(31). |
| |
| (3) the end of packet is BIT(30). |
| |
| (4) A packet ID is stored in bits 19..16. This packet ID is |
| determined by software and is typically a rolling counter. |
| |
| (5) Padding shall be inserted as needed so that the Header CRC, |
| Header response, Footer CRC, Footer response are always in |
| Byte0. Padding is inserted by software for writes, and on reads |
| software shall discard the padding added by the hardware. |
| |
| Example format |
| ~~~~~~~~~~~~~~ |
| |
| The following table represents the sequence provided to PDI0 for a |
| write command followed by a read command. |
| |
| :: |
| |
| +---+---+--------+---------------+---------------+ |
| + 1 | 0 | ID = 0 | WR HDR[1] | WR HDR[0] | |
| + | | | WR HDR[3] | WR HDR[2] | |
| + | | | WR HDR[5] | WR HDR[4] | |
| + | | | pad | WR HDR CRC | |
| + | | | WR Data[1] | WR Data[0] | |
| + | | | WR Data[3] | WR Data[2] | |
| + | | | WR Data[n-2] | WR Data[n-3] | |
| + | | | pad | WR Data[n-1] | |
| + 0 | 1 | | pad | WR Data CRC | |
| +---+---+--------+---------------+---------------+ |
| + 1 | 0 | ID = 1 | RD HDR[1] | RD HDR[0] | |
| + | | | RD HDR[3] | RD HDR[2] | |
| + | | | RD HDR[5] | RD HDR[4] | |
| + 0 | 1 | | pad | RD HDR CRC | |
| +---+---+--------+---------------+---------------+ |
| |
| |
| The table below represents the data received on PDI1 for the same |
| write command followed by a read command. |
| |
| :: |
| |
| +---+---+--------+---------------+---------------+ |
| + 1 | 0 | ID = 0 | pad | WR Hdr Rsp | |
| + 0 | 1 | | pad | WR Ftr Rsp | |
| +---+---+--------+---------------+---------------+ |
| + 1 | 0 | ID = 0 | pad | Rd Hdr Rsp | |
| + | | | RD Data[1] | RD Data[0] | |
| + | | | RD Data[3] | RD Data[2] | |
| + | | | RD HDR[n-2] | RD Data[n-3] | |
| + | | | pad | RD Data[n-1] | |
| + | | | pad | RD Data CRC | |
| + 0 | 1 | | pad | RD Ftr Rsp | |
| +---+---+--------+---------------+---------------+ |
