How to set a memory address to GPDMA_CxLBAR register when only 16 bit region is open to hold the address?

[psabela]

My linked-list object's base address in memory is 0x200bffbc.   How can I save this address in GPDMA_CxLBAR register (that holds "the linked-list base address of the memory region, for a given channel x, from which the LLIs describing the programmed sequence of the GPDMA transfers, are conditionally and automatically updated")  when GPDMA_CxLBAR designated region for the address (LBA[31:16]) is only 16 bits long?

Anyone can help please? 

[psabela]

Never mind.  Got it at last.

[Amel NASRI]

Hi @psabela ,

Glad to know that your issue is resolved.

But how you did? That may be interesting for other to know and avoid facing a similar problem.

-Amel

[psabela · Accepted solution]

Example of creating link list in code
and setting GPDMA_CxLBAR and GPDMA_CxLLR registers.

//Create GPDMA link list in code.  Example:
//1. Link list item:
typedef struct {
  volatile uint32_t CTR1_register; 
  volatile uint32_t CTR2_register; 
  volatile uint32_t CBR1_register; 
  volatile uint32_t CSAR_register; //Source address for the transfer.
  volatile uint32_t CDAR_register; //Destination address for the transfer.
  volatile uint32_t CTR3_register;
  volatile uint32_t CBR2_register;
  volatile uint32_t CLLR_register; 
} LinkListItem_t;

//2. List object with 2 linked list items and their memory address:
typedef struct {
  LinkListItem_t node1;   //node1 address: 0x200bffa8 (same as base address)
  LinkListItem_t node2;   //node2 address: 0x200bffc8
} LinkList_t;             //base address:  0x200bffa8

GPDMA channel x linked-list base address register (GPDMA_CxLBAR):
In this example, the address of the link list structure object is 0x200bffa8

GPDMA_CxLBAR->LBA = 0x200b
GPDMA_CxLBAR      = 0x200b0000

GPDMA channel x linked-list address register (GPDMA_CxLLR):
The address of node1 is 0x200bffa8.  Node 0 (staring value of LLR) points to node 1.
f      |f      |a      |8
1111|1111|1010|1000
11|1111|1110|1010|00    Bits LA[15:2]Bits 1:0 Reserved
3  |f      |e      |a

//Bits 15:2 LA[15:2]: pointer (16-bit low-significant address) to the next linked-list data structure
pNode0->CLLR_register.LA = 0x3fea;
pNode0->CLLR_register    = 0xfe01ffa8;  //the last 4 hex values aggree to the last 4 hex of the address 

The address of node2 is 0x200bffc8.  The node 1 points to node 2.
f      |f      |c      |8   
1111|1111|1100|1000
11|1111|1111|0010|00  Bits LA[15:2]Bits 1:0 Reserved
3 |f       |f      |2

//Bits 15:2 LA[15:2]: pointer (16-bit low-significant address) to the next linked-list data structure
pNode1->CLLR_register.LA = 0x3ff2;
pNode1->CLLR_register    = 0xfe01ffc8;  //the last 4 hex values aggree to the last 4 hex of the address 

The node 2 points back to node 1. (The address of node1 is 0x200bffa8.)

//Bits 15:2 LA[15:2]: pointer (16-bit low-significant address) to the next linked-list data structure
pNode2->CLLR_register.LA = 0x3fea;
pNode2->CLLR_register    = 0xfe01ffa8;  //the last 4 hex values aggree to the last 4 hex of the address 

cc @Amel NASRI