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Add prefetching to spimemio

This commit is contained in:
Clifford Wolf 2017-07-29 21:34:11 +02:00
parent fdb2e5feb5
commit 995f366d0e
1 changed files with 18 additions and 1 deletions
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19
spiflash/spimemio.v
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@ -11,12 +11,15 @@ module spimemio (
output reg spi_mosi, output reg spi_mosi,
input spi_miso input spi_miso
); );
parameter ENABLE_PREFETCH = 1;
reg [23:0] addr_q; reg [23:0] addr_q;
reg addr_q_vld; reg addr_q_vld;
reg [31:0] buffer; reg [31:0] buffer;
reg [6:0] xfer_cnt; reg [6:0] xfer_cnt;
reg xfer_wait; reg xfer_wait;
reg prefetch;
always @(posedge clk) begin always @(posedge clk) begin
ready <= 0; ready <= 0;
@ -27,6 +30,7 @@ module spimemio (
buffer <= 8'hAB << 24; buffer <= 8'hAB << 24;
addr_q_vld <= 0; addr_q_vld <= 0;
xfer_wait <= 0; xfer_wait <= 0;
prefetch <= 0;
end else end else
if (xfer_cnt) begin if (xfer_cnt) begin
if (spi_cs) begin if (spi_cs) begin
@ -50,8 +54,10 @@ module spimemio (
if (addr_q_vld && addr_q == addr) begin if (addr_q_vld && addr_q == addr) begin
addr_q <= addr + 4; addr_q <= addr + 4;
addr_q_vld <= 1; addr_q_vld <= 1;
xfer_cnt <= 32; if (!prefetch)
xfer_cnt <= 32;
xfer_wait <= 1; xfer_wait <= 1;
prefetch <= 0;
end else begin end else begin
spi_cs <= 1; spi_cs <= 1;
buffer <= {8'h 03, addr}; buffer <= {8'h 03, addr};
@ -59,7 +65,18 @@ module spimemio (
addr_q_vld <= 1; addr_q_vld <= 1;
xfer_cnt <= 64; xfer_cnt <= 64;
xfer_wait <= 1; xfer_wait <= 1;
prefetch <= 0;
end end
end else if (ENABLE_PREFETCH && !prefetch) begin
prefetch <= 1;
xfer_cnt <= 32;
end
if (ENABLE_PREFETCH && resetn && prefetch && valid && !ready && addr_q != addr) begin
prefetch <= 0;
xfer_cnt <= 0;
xfer_wait <= 0;
spi_sclk <= 1;
end end
end end
endmodule endmodule