Reading UART Rx count register on Mesa 5i25/6i25

i = hm2_get_uart(&hm2, name);
inst = &hm2->uart.instance[i];
hm2->llio->read(hm2->llio, inst->rx_fifo_count_addr, &buff, sizeof(rtapi_u32));

1. If I want to add such read/write functions for RX FIFO count register and RX MODE/STATUS Register,
   then I have to add them to github.com/LinuxCNC/linuxcnc/blob/master...mesa-hostmot2/uart.c ?
2. Or can I use/define these functions solely within my own component by merely including github.com/LinuxCNC/linuxcnc/blob/master...-hostmot2/hostmot2.h ?
3. A kind of callback function called each time from within my component if n <=16 bytes are written to the Rx FIFO
   would be nice, but I do not know how to do this - at least at the moment.

PCW wrote:

If you are going to write new low level interface code, you might consider the PacketUART

Its more oriented towards packetized data (with interpacket timeouts settable from 1 to 255 bittimes for RX framing)
and also can have RX/TX buffers of up to 1024 bytes

andypugh wrote:

Basically the hostmot2 driver exports a function that returns a pointer to the UART structure, and you can ask for that pointer.

 213 EXPORT_SYMBOL_GPL(hm2_get_uart);
 214 int hm2_get_uart(hostmot2_t** hm2, char *name){
 215     struct rtapi_list_head *ptr;
 216     int i;
 217     rtapi_list_for_each(ptr, &hm2_list) {
 218         *hm2 = rtapi_list_entry(ptr, hostmot2_t, list);
 219         if ((*hm2)->uart.num_instances > 0) {
 220             for (i = 0; i < (*hm2)->uart.num_instances ; i++) {
 221                 if (!strcmp((*hm2)->uart.instance[i].name, name)) {return i;}
 222             }
 223         }
 224     }
 225     return -1;
 226 }

PktUARTx data register (write only)

[...]

0x6100 PktUARTx 0 data register
0x6104 PktUARTx 1 data register
0x6108 PktUARTx 2 data register
0x610c PktUARTx 3 data register
0x6110 PktUARTx 4 data register

...

PktUARTx send count register read/write

[...]

0x6200 PktUARTx 0 send count register
0x6204 PktUARTx 1 send count register
0x6208 PktUARTx 2 send count register
0x620C PktUARTx 3 send count register

• Hope I got the difference between UART and PktUART correctly.
  My hm2_pktuart_instance_t looks like:

  typedef struct {
      u32 clock_freq;
      u32 bitrate;
      u32 tx_fifo_count_addr;
      u32 tx_bitrate_addr;
      u32 tx_addr;
      u32 tx_mode_addr;
      u32 rx_fifo_count_addr;
      u32 rx_bitrate_addr;
      u32 rx_addr;
      u32 rx_mode_addr;
      char name[HAL_NAME_LEN+1];
  } hm2_pktuart_instance_t;

  So there is only one rx_addr and tx_addr per instance of PktUART?


• I defined Module Descriptor constants for PktUART as:
  
  #define HM2_GTAG_PKTUART_TX (90) // PktUART uses same addresses as normal UART with
  #define HM2_GTAG_PKTUART_RX (110) // the assumption you would not use both in one config
  Hope that's ok.
  

  #define HM2_GTAG_PKTUART_TX        (27)  // PktUART uses same addresses as normal UART with 
  #define HM2_GTAG_PKTUART_RX        (28) // the assumption you would not use both in one config

  because IDROMConst.vhd says:

  constant PktUARTTTag : std_logic_vector(7 downto 0) := x"1B";     --  =27
  		constant PktUTDataPin : std_logic_vector(7 downto 0) := x"81";
  		constant PktUTDrvEnPin : std_logic_vector(7 downto 0) := x"82";		
  
  	constant PktUARTRTag : std_logic_vector(7 downto 0) := x"1C";  -- =28
  		constant PktURDataPin : std_logic_vector(7 downto 0) := x"01"




• I do not quite understand how the burst mode of PktUARTx send count register functions.
  Suppose I want to send two datagrams of 10 bytes length each.
  Let the datagram be: 0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A .
  Then I do for the first datagram:
  
  write 0x04030201 to PktUARTx data register
  write 0x08070605 to PktUARTx data register
  write 0x00000A09 to PktUARTx data register
  and then do the same for the second datagram .
  
  Writing 0x0000000A to PktUARTx sendcount register sends out the first datagram.
  Will writing 0x0000000A to PktUARTx sendcount register send out the second datagram?