csr_interface.h

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/*a Includes */
include "apb.h"

/*a Types */
/*t t_csr_request */
typedef struct {
    bit valid;
    bit read_not_write;
    bit[16] select;
    bit[16] address;
    bit[32] data;
} t_csr_request;

/*t t_csr_response */
typedef struct {
    bit acknowledge;
    bit read_data_valid;
    bit read_data_error;
    bit[32] read_data;
} t_csr_response;

/*t t_csr_access */
typedef struct {
    bit valid;
    bit read_not_write;
    bit[16] address;
    bit[32] data;
} t_csr_access;

/*t t_csr_access_data */
typedef bit[32] t_csr_access_data;


/*a Modules */
/*m csr_target_apb
 *
 * CSR target that drives an APB
 *
 */
extern
module csr_target_apb( clock                    clk           "Clock for the CSR interface, possibly gated version of master CSR clock",
                       input bit                reset_n       "Active low reset",
                       input t_csr_request      csr_request   "Pipelined csr request interface input",
                       output t_csr_response    csr_response  "Pipelined csr request interface response",
                       output t_apb_request     apb_request   "APB request to target",
                       input t_apb_response     apb_response  "APB response from target",
                       input bit[16]            csr_select    "Hard-wired select value for the client"
    )
{
    timing to   rising clock clk csr_request, csr_select;
    timing from rising clock clk csr_response;

    timing from rising clock clk apb_request;
    timing to   rising clock clk apb_response;
}

/*m csr_target_csr
 *
 * CSR target that drives a CSR access (select, read, write, data)
 *
 */
extern
module csr_target_csr( clock                       clk           "Clock for the CSR interface, possibly gated version of master CSR clock",
                       input bit                reset_n       "Active low reset",
                       input t_csr_request      csr_request   "Pipelined csr request interface input",
                       output t_csr_response    csr_response  "Pipelined csr request interface response",
                       output t_csr_access      csr_access    "Registered CSR access request to client",
                       input  t_csr_access_data csr_access_data "Read data valid combinatorially based on csr_access",
                       input bit[16]            csr_select    "Hard-wired select value for the client"
    )
{
    timing to   rising clock clk csr_request, csr_select;
    timing from rising clock clk csr_response;

    timing from rising clock clk csr_access;
    timing to   rising clock clk csr_access_data;
}

/*m csr_master_apb
 *
 * APB target that drive a CSR master
 *
 */
extern
module csr_master_apb( clock                    clk           "Clock for the CSR interface; a superset of all targets clock",
                       input bit                reset_n       "Active low reset",
                       input t_apb_request      apb_request   "APB request from master",
                       output t_apb_response    apb_response  "APB response to master",
                       input t_csr_response     csr_response  "Pipelined csr request interface response",
                       output t_csr_request     csr_request   "Pipelined csr request interface output"
    )
{
    timing to   rising clock clk csr_response;
    timing from rising clock clk csr_request;

    timing to   rising clock clk apb_request;
    timing from rising clock clk apb_response;
}

/*m csr_target_timeout
 *
 * CSR target that implements a timeout
 *
 * One of these can be placed on a CSR bus tree to terminate transactions that never complete
 *
 */
extern
module csr_target_timeout( clock                       clk        "Clock for the CSR interface, possibly gated version of master CSR clock",
                           input bit                reset_n       "Active low reset",
                           input t_csr_request      csr_request   "Pipelined csr request interface input",
                           output t_csr_response    csr_response  "Pipelined csr request interface response",
                           input bit[16]            csr_timeout   "Number of cycles to wait for until auto-acknowledging a request"
    )
{
    timing to   rising clock clk csr_request, csr_timeout;
    timing from rising clock clk csr_response;
}