verilog/dv/caravel/mgmt_soc/uart/uart.c

/*
 * SPDX-FileCopyrightText: 2020 Efabless Corporation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * SPDX-License-Identifier: Apache-2.0
 */

#include "../../defs.h"
#include "../../stub.c"

// --------------------------------------------------------

void main()
{
    int j;

    // Configure I/O:  High 16 bits of user area used for a 16-bit
    // word to write and be detected by the testbench verilog.
    // Only serial Tx line is used in this testbench.  It connects
    // to mprj_io[6].  Since all lines of the chip are input or
    // high impedence on startup, the I/O has to be configured
    // for output

    reg_mprj_io_31 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_30 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_29 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_28 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_27 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_26 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_25 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_24 = GPIO_MODE_MGMT_STD_OUTPUT;

    reg_mprj_io_23 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_22 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_21 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_20 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_19 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_18 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_17 = GPIO_MODE_MGMT_STD_OUTPUT;
    reg_mprj_io_16 = GPIO_MODE_MGMT_STD_OUTPUT;

    reg_mprj_io_6 = GPIO_MODE_MGMT_STD_OUTPUT;

    // Set clock to 64 kbaud and enable the UART.  It is important to do this
    // before applying the configuration, or else the Tx line initializes as
    // zero, which indicates the start of a byte to the receiver.

    reg_uart_clkdiv = 625;
    reg_uart_enable = 1;

    // Now, apply the configuration
    reg_mprj_xfer = 1;
    while (reg_mprj_xfer == 1);

    // Start test
    reg_mprj_datal = 0xa0000000;

    // This should appear at the output, received by the testbench UART.
    // (Makes simulation time long.)
    print("Monitor: Test UART (RTL) passed\n");

    // Allow transmission to complete before signalling that the program
    // has ended.
    for (j = 0; j < 20; j++);
    reg_mprj_datal = 0xab000000;
}