doom_riscv/cores/hyperram/doc/hram_regs.md

HyperRAM controller Registers

FIXME: Document the manual command submission for link training

Control

Control / Status (Read / Write addr 0x00)

,-----------------------------------------------------------------------------------------------,
|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
|-----------------------------------------------------------------------------------------------|
|               /             |phase| phy_delay |  cap_lat  |  cmd_lat  |     /     |ir|ic|rs|ru|
'-----------------------------------------------------------------------------------------------'

 * [21:20] - phy_phase : PHY config - Phase select
 * [19:16] - phy_delay : PHY config - Delay select
 * [15:12] - cap_lat   : Capture latency
 * [11: 8] - cmd_lat   : Command latency
 * [    3] - ir        : Idle 'run' mode
 * [    2] - ic        : Idle 'config' mode
 * [    1] - rs        : Reset
 * [    0] - ru        : Running

Command Execute (Write only addr 0x01)

,-----------------------------------------------------------------------------------------------,
|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
|-----------------------------------------------------------------------------------------------|
|                             /                             |    len    |    lat    |  /  |as|rw|
'-----------------------------------------------------------------------------------------------'

 * [11: 8] - len : Length ( # of xfer - 1 )
 * [ 7: 4] - lat : Latency counter
 * [ 3: 2] - cs  : Chip Select
 * [    1] - as  : Memory (0) / Register (1)
 * [    0] - rw  : Write  (0) / Read     (1)

Word Queue Write

To put a word in the queue, write the attributes first, then write the corresponding data word. The write to the data register will trigger the queuing with whatever attributes were last set.

The newly written word will always end up in last position (pos=2) and the words that were previously in positions 1 & 2 will be in position 0 & 1.

Word Enqueue - Data (Write only addr 0x02)

,-----------------------------------------------------------------------------------------------,
|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
|-----------------------------------------------------------------------------------------------|
|                                              data                                             |
'-----------------------------------------------------------------------------------------------'

 * [31: 0] - data : Data word to queue

Word Enqueue - Attributes (Write only addr 0x03)

,-----------------------------------------------------------------------------------------------,
|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
|-----------------------------------------------------------------------------------------------|
|                                           /                                 |  oe |   rwds    |
'-----------------------------------------------------------------------------------------------'

 * [ 5: 4] - oe   : Output Enable (per 16 bits)
 * [ 3: 0] - rwds : RWDS value     (per 8 bits)

Word Queue Read

To read a word from the queue, read the attributes first to get the RWDS values and then read the corresponding data word. The read of the data register will trigger the de-queuing.

The words that is read is the one that was first, at position 0 in the queue. The words that were previously in positions 1 & 2 will be moved up to positions 0 & 1.

Word Dequeue - Data (Read only addr 0x02)

,-----------------------------------------------------------------------------------------------,
|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
|-----------------------------------------------------------------------------------------------|
|                                              data                                             |
'-----------------------------------------------------------------------------------------------'

 * [31: 0] - data : Data word to queue

Word Dequeue - Attributes (Read only addr 0x03)

,-----------------------------------------------------------------------------------------------,
|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
|-----------------------------------------------------------------------------------------------|
|                                             /                                     |   rwds    |
'-----------------------------------------------------------------------------------------------'

 * [ 3: 0] - rwds : RWDS value     (per 8 bits)