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Fixed UART FIFO bugs and added FIFO tests

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This commit is contained in:
slmnemo 2022-07-22 17:13:19 -07:00
parent ba2dcf6da4
commit ca4511b6dc
3 changed files with 40 additions and 4 deletions
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11
pipelined/src/uncore/uartPC16550D.sv
View file

@ -324,7 +324,9 @@ module uartPC16550D(
if (~PRESETn) begin
rxfifohead <= #1 0; rxfifotail <= #1 0; rxdataready <= #1 0; RXBR <= #1 0;
end else begin
if (rxstate == UART_DONE) begin
if (~MEMWb & (A == 3'b010) & Din[1]) begin
rxfifohead <= #1 0; rxfifotail <= #1 0; rxdataready <= #1 0;
end else if (rxstate == UART_DONE) begin
RXBR <= #1 {rxoverrunerr, rxparityerr, rxframingerr, rxdata}; // load recevive buffer register
if (rxoverrunerr) $warning("UART RX Overrun Error\n");
if (rxparityerr) $warning("UART RX Parity Error\n");
@ -337,7 +339,8 @@ module uartPC16550D(
end else if (~MEMRb & A == 3'b000 & ~DLAB) begin // reading RBR updates ready / pops fifo
if (fifoenabled) begin
if (~rxfifoempty) rxfifotail <= #1 rxfifotail + 1;
if (rxfifoempty) rxdataready <= #1 0;
// if (rxfifoempty) rxdataready <= #1 0;
if (rxfifoentries == 1) rxdataready <= #1 0; // When reading the last entry, data ready becomes zero
end else begin
rxdataready <= #1 0;
RXBR <= #1 {1'b0, RXBR[9:0]}; // Ben 31 March 2022: I added this so that rxoverrunerr permanently goes away upon reading RBR (when not in FIFO mode)
@ -448,6 +451,8 @@ module uartPC16550D(
always_ff @(posedge PCLK, negedge PRESETn)
if (~PRESETn) begin
txfifohead <= #1 0; txfifotail <= #1 0; txhrfull <= #1 0; txsrfull <= #1 0; TXHR <= #1 0; txsr <= #1 12'hfff;
end else if (~MEMWb & (A == 3'b010) & Din[2]) begin
txfifohead <= #1 0; txfifotail <= #1 0;
end else begin
if (~MEMWb & A == 3'b000 & ~DLAB) begin // writing transmit holding register or fifo
if (fifoenabled) begin
@ -461,7 +466,7 @@ module uartPC16550D(
end
if (txstate == UART_IDLE) begin // move data into tx shift register if available
if (fifoenabled) begin
if (~txfifoempty) begin
if (~txfifoempty & ~txsrfull) begin
txsr <= #1 txdata;
txfifotail <= #1 txfifotail+1;
txsrfull <= #1 1;

13
tests/wally-riscv-arch-test/riscv-test-suite/rv32i_m/privilege/references/WALLY-uart-01.reference_output
View file

@ -39,6 +39,17 @@ ffffffB8
ffffffC2 # FIFO interrupt
0000C101
00000000
ffffffC1
0000C401
ffffffA5
ffffffC1
00000001
00000002
00000061
00000003
00000060
0000C101
ffffffC1
00000060
0000000b # ecall from test termination

20
tests/wally-riscv-arch-test/riscv-test-suite/rv32i_m/privilege/src/WALLY-uart-01.S
View file

@ -160,5 +160,25 @@ test_cases:
.4byte UART_THR, 0x00, write08_test # write 0 to transmit register
.4byte 0x0, 0xC101, uart_data_wait # no interrupts pending (transmitter interrupt squashed by early read)
.4byte UART_RBR, 0x00, read08_test # read 0 from buffer register
.4byte UART_THR, 0xA5, write08_test # Write A5 to transmit register
.4byte UART_THR, 0x01, write08_test # Write 1 to transmit register
.4byte UART_IIR, 0xC1, read08_test # no interrupts pending
.4byte UART_THR, 0x02, write08_test # Write 2 to transmit register
.4byte UART_THR, 0x03, write08_test # Write 3 to transmit register
.4byte 0x0, 0xC401, uart_data_wait # Interrupt due to data ready
.4byte UART_RBR, 0xA5, read08_test # Read A5 from buffer register
.4byte UART_IIR, 0xC2, read08_test # Data ready interrupt cleared
.4byte UART_RBR, 0x01, read08_test # Read 1 from buffer register
.4byte UART_RBR, 0x02, read08_test # Read 2 from buffer register
.4byte UART_LSR, 0x61, read08_test # Data ready, 1 item left in FIFO
.4byte UART_RBR, 0x03, read08_test # Read 3 from buffer register
.4byte UART_LSR, 0x60, read08_test # No data ready, FIFO is empty
.4byte UART_THR, 0xFF, write08_test # Write FF to transmit register
.4byte UART_THR, 0xFE, write08_test # Write FE to transmit register
.4byte 0x0, 0xC101, uart_data_wait # Interrupt due to data ready
.4byte UART_FCR, 0xC7, write08_test # Clear all bytes in FIFO
.4byte UART_FCR, 0xC1, read08_test # Check that FCR clears bits 1 and 2 when written to 1
.4byte UART_LSR, 0x60, read08_test # No data ready, FIFO cleared by writing to FCR
.4byte 0x0, 0x0, terminate_test