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xfcp: Fix APB implementation

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Signed-off-by: Alex Forencich <alex@alexforencich.com>
This commit is contained in:
Alex Forencich
2026-03-13 01:23:31 -07:00
parent 23279469c9
commit dc262cc4c4
1 changed files with 12 additions and 13 deletions
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25
src/xfcp/rtl/taxi_xfcp_mod_apb.sv
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@@ -210,8 +210,8 @@ always_comb begin
addr_next = addr_reg;
data_next = data_reg;
m_apb_psel_next = m_apb_psel_reg;
m_apb_penable_next = m_apb_penable_reg;
m_apb_psel_next = 1'b0;
m_apb_penable_next = 1'b0;
m_apb_pwrite_next = m_apb_pwrite_reg;
m_apb_pstrb_next = m_apb_pstrb_reg;
@@ -221,8 +221,6 @@ always_comb begin
xfcp_usp_ds_tready_next = xfcp_usp_us_tready_int_early;
id_ptr_next = '0;
m_apb_psel_next = 1'b0;
if (xfcp_usp_ds.tready && xfcp_usp_ds.tvalid) begin
if (xfcp_usp_ds.tlast) begin
// last asserted, ignore cycle
@@ -341,7 +339,6 @@ always_comb begin
// set initial word offset
count_next = addr_reg & WORD_AM;
m_apb_pstrb_next = '0;
m_apb_psel_next = 1'b1;
data_next = '0;
if (m_apb_pwrite_reg) begin
// start writing
@@ -356,6 +353,8 @@ always_comb begin
end
end else begin
// start reading
m_apb_psel_next = 1'b1;
m_apb_pwrite_next = 1'b0;
xfcp_usp_ds_tready_next = !(last_cycle_reg || (xfcp_usp_ds.tvalid && xfcp_usp_ds.tlast));
state_next = STATE_READ_1;
end
@@ -377,12 +376,14 @@ always_comb begin
// wait for data
m_apb_psel_next = 1'b1;
m_apb_penable_next = 1'b1;
m_apb_pwrite_next = 1'b0;
// drop padding
xfcp_usp_ds_tready_next = !(last_cycle_reg || (xfcp_usp_ds.tvalid && xfcp_usp_ds.tlast));
if (m_apb.psel && m_apb.penable && m_apb.pready) begin
// read cycle complete, store result
m_apb_psel_next = 1'b0;
m_apb_penable_next = 1'b0;
data_next = m_apb.prdata;
addr_next = addr_reg + (1 << (ADDR_W-VALID_ADDR_W+BYTE_AW));
@@ -393,8 +394,6 @@ always_comb begin
end
STATE_READ_2: begin
// send data
m_apb_psel_next = 1'b1;
m_apb_penable_next = 1'b0;
// drop padding
xfcp_usp_ds_tready_next = !(last_cycle_reg || (xfcp_usp_ds.tvalid && xfcp_usp_ds.tlast));
@@ -410,7 +409,6 @@ always_comb begin
if (ptr_reg == 1) begin
// last word of read
xfcp_usp_us_tlast_int = 1'b1;
m_apb_psel_next = 1'b0;
if (!(last_cycle_reg || (xfcp_usp_ds.tvalid && xfcp_usp_ds.tlast))) begin
state_next = STATE_WAIT_LAST;
end else begin
@@ -420,6 +418,8 @@ always_comb begin
end else if (count_reg == (STRB_W*BYTE_W/8)-1) begin
// end of stored data word; read the next one
count_next = 0;
m_apb_psel_next = 1'b1;
m_apb_pwrite_next = 1'b0;
state_next = STATE_READ_1;
end else begin
state_next = STATE_READ_2;
@@ -431,8 +431,6 @@ always_comb begin
STATE_WRITE_1: begin
// write data
xfcp_usp_ds_tready_next = 1'b1;
m_apb_psel_next = 1'b1;
m_apb_penable_next = 1'b0;
if (xfcp_usp_ds.tready && xfcp_usp_ds.tvalid) begin
// store word
@@ -444,7 +442,8 @@ always_comb begin
// have full word or at end of block, start write operation
count_next = 0;
xfcp_usp_ds_tready_next = 1'b0;
m_apb_penable_next = 1'b1;
m_apb_psel_next = 1'b1;
m_apb_pwrite_next = 1'b1;
state_next = STATE_WRITE_2;
if (xfcp_usp_ds.tlast) begin
// last asserted, nothing further to write
@@ -452,7 +451,6 @@ always_comb begin
end
end else if (xfcp_usp_ds.tlast) begin
// last asserted, return to idle
m_apb_psel_next = 1'b0;
state_next = STATE_IDLE;
end else begin
state_next = STATE_WRITE_1;
@@ -465,11 +463,13 @@ always_comb begin
// wait for write completion
m_apb_psel_next = 1'b1;
m_apb_penable_next = 1'b1;
m_apb_pwrite_next = 1'b1;
if (m_apb.psel && m_apb.penable && m_apb.pready) begin
// end of write operation
data_next = '0;
addr_next = addr_reg + (1 << (ADDR_W-VALID_ADDR_W+BYTE_AW));
m_apb_psel_next = 1'b0;
m_apb_penable_next = 1'b0;
m_apb_pstrb_next = '0;
if (ptr_reg == 0) begin
@@ -479,7 +479,6 @@ always_comb begin
state_next = STATE_WAIT_LAST;
end else begin
xfcp_usp_ds_tready_next = xfcp_usp_us_tready_int_early;
m_apb_psel_next = 1'b0;
state_next = STATE_IDLE;
end
end else begin