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Introduce addr_to_wb() and wb_to_addr() helpers

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These convert addresses to/from wishbone addresses, and use them
in parts of the caches, in order to make the code a bit more readable.

Along the way, rename some functions in the caches to make it a bit
clearer what they operate on and fix a bug in the icache STOP_RELOAD state where
the wb address wasn't properly converted.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2021-09-27 21:53:52 +10:00
parent d745995207
commit 5cfa65e836
3 changed files with 40 additions and 23 deletions
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13
dcache.vhdl
View File

@ -452,7 +452,7 @@ architecture rtl of dcache is
end;
-- Returns whether this is the last row of a line
function is_last_row_addr(addr: wishbone_addr_type; last: row_in_line_t) return boolean is
function is_last_row_wb_addr(addr: wishbone_addr_type; last: row_in_line_t) return boolean is
begin
return unsigned(addr(LINE_OFF_BITS - ROW_OFF_BITS - 1 downto 0)) = last;
end;
@ -464,7 +464,7 @@ architecture rtl of dcache is
end;
-- Return the address of the next row in the current cache line
function next_row_addr(addr: wishbone_addr_type) return std_ulogic_vector is
function next_row_wb_addr(addr: wishbone_addr_type) return std_ulogic_vector is
variable row_idx : std_ulogic_vector(ROW_LINEBITS-1 downto 0);
variable result : wishbone_addr_type;
begin
@ -804,8 +804,7 @@ begin
variable addr : real_addr_t;
begin
if rising_edge(clk) then
addr := (others => '0');
addr(snoop_in.adr'left + ROW_OFF_BITS downto ROW_OFF_BITS) := snoop_in.adr;
addr := addr_to_real(wb_to_addr(snoop_in.adr));
snoop_tag_set <= cache_tags(get_index(addr));
snoop_wrtag <= get_tag(addr);
snoop_index <= get_index(addr);
@ -1381,7 +1380,7 @@ begin
-- Main state machine
case r1.state is
when IDLE =>
r1.wb.adr <= req.real_addr(r1.wb.adr'left + ROW_OFF_BITS downto ROW_OFF_BITS);
r1.wb.adr <= addr_to_wb(req.real_addr);
r1.wb.sel <= req.byte_sel;
r1.wb.dat <= req.data;
r1.dcbz <= req.dcbz;
@ -1469,12 +1468,12 @@ begin
-- If we are still sending requests, was one accepted ?
if wishbone_in.stall = '0' and r1.wb.stb = '1' then
-- That was the last word ? We are done sending. Clear stb.
if is_last_row_addr(r1.wb.adr, r1.end_row_ix) then
if is_last_row_wb_addr(r1.wb.adr, r1.end_row_ix) then
r1.wb.stb <= '0';
end if;
-- Calculate the next row address
r1.wb.adr <= next_row_addr(r1.wb.adr);
r1.wb.adr <= next_row_wb_addr(r1.wb.adr);
end if;
-- Incoming acks processing

30
icache.vhdl
View File

@ -235,7 +235,7 @@ architecture rtl of icache is
end;
-- Return the cache row index (data memory) for an address
function get_row(addr: std_ulogic_vector) return row_t is
function get_row(addr: std_ulogic_vector(63 downto 0)) return row_t is
begin
return to_integer(unsigned(addr(SET_SIZE_BITS - 1 downto ROW_OFF_BITS)));
end;
@ -249,9 +249,9 @@ architecture rtl of icache is
end;
-- Returns whether this is the last row of a line
function is_last_row_addr(addr: wishbone_addr_type; last: row_in_line_t) return boolean is
function is_last_row_wb_addr(wb_addr: wishbone_addr_type; last: row_in_line_t) return boolean is
begin
return unsigned(addr(LINE_OFF_BITS - ROW_OFF_BITS - 1 downto 0)) = last;
return unsigned(wb_addr(LINE_OFF_BITS - ROW_OFF_BITS - 1 downto 0)) = last;
end;
-- Returns whether this is the last row of a line
@ -261,15 +261,15 @@ architecture rtl of icache is
end;
-- Return the address of the next row in the current cache line
function next_row_addr(addr: wishbone_addr_type)
function next_row_wb_addr(wb_addr: wishbone_addr_type)
return std_ulogic_vector is
variable row_idx : std_ulogic_vector(ROW_LINEBITS-1 downto 0);
variable result : wishbone_addr_type;
begin
-- Is there no simpler way in VHDL to generate that 3 bits adder ?
row_idx := addr(ROW_LINEBITS - 1 downto 0);
row_idx := wb_addr(ROW_LINEBITS - 1 downto 0);
row_idx := std_ulogic_vector(unsigned(row_idx) + 1);
result := addr;
result := wb_addr;
result(ROW_LINEBITS - 1 downto 0) := row_idx;
return result;
end;
@ -299,10 +299,9 @@ architecture rtl of icache is
end;
-- Get the tag value from the address
function get_tag(addr: std_ulogic_vector(REAL_ADDR_BITS - 1 downto 0);
endian: std_ulogic) return cache_tag_t is
function get_tag(addr: real_addr_t; endian: std_ulogic) return cache_tag_t is
begin
return endian & addr(REAL_ADDR_BITS - 1 downto SET_SIZE_BITS);
return endian & addr(addr'left downto SET_SIZE_BITS);
end;
-- Read a tag from a tag memory row
@ -523,7 +522,7 @@ begin
-- used for cache miss processing if needed
--
req_laddr <= (63 downto REAL_ADDR_BITS => '0') &
real_addr(REAL_ADDR_BITS - 1 downto ROW_OFF_BITS)&
real_addr(REAL_ADDR_BITS - 1 downto ROW_OFF_BITS) &
(ROW_OFF_BITS-1 downto 0 => '0');
-- Test if pending request is a hit on any way
@ -655,8 +654,7 @@ begin
-- Detect snooped writes and decode address into index and tag
-- Since we never write, any write should be snooped
snoop_valid <= wb_snoop_in.cyc and wb_snoop_in.stb and wb_snoop_in.we;
snoop_addr := (others => '0');
snoop_addr(wb_snoop_in.adr'left + ROW_OFF_BITS downto ROW_OFF_BITS) := wb_snoop_in.adr;
snoop_addr := addr_to_real(wb_to_addr(wb_snoop_in.adr));
snoop_index <= get_index(snoop_addr);
snoop_cache_tags := cache_tags(get_index(snoop_addr));
snoop_tag := get_tag(snoop_addr, '0');
@ -715,7 +713,7 @@ begin
-- Prep for first wishbone read. We calculate the address of
-- the start of the cache line and start the WB cycle.
--
r.wb.adr <= req_laddr(r.wb.adr'left + ROW_OFF_BITS downto ROW_OFF_BITS);
r.wb.adr <= addr_to_wb(req_laddr);
r.wb.cyc <= '1';
r.wb.stb <= '1';
@ -747,12 +745,12 @@ begin
if wishbone_in.stall = '0' and r.wb.stb = '1' then
-- That was the last word ? We are done sending. Clear stb.
--
if is_last_row_addr(r.wb.adr, r.end_row_ix) then
if is_last_row_wb_addr(r.wb.adr, r.end_row_ix) then
r.wb.stb <= '0';
end if;
-- Calculate the next row address
r.wb.adr <= next_row_addr(r.wb.adr);
r.wb.adr <= next_row_wb_addr(r.wb.adr);
end if;
-- Abort reload if we get an invalidation
@ -783,7 +781,7 @@ begin
when STOP_RELOAD =>
-- Wait for all outstanding requests to be satisfied, then
-- go to IDLE state.
if get_row_of_line(r.store_row) = get_row_of_line(get_row(r.wb.adr)) then
if get_row_of_line(r.store_row) = get_row_of_line(get_row(wb_to_addr(r.wb.adr))) then
r.wb.cyc <= '0';
r.state <= IDLE;
end if;

20
wishbone_types.vhdl
View File

@ -15,6 +15,9 @@ package wishbone_types is
subtype wishbone_data_type is std_ulogic_vector(wishbone_data_bits-1 downto 0);
subtype wishbone_sel_type is std_ulogic_vector(wishbone_sel_bits-1 downto 0);
function addr_to_wb(addr: std_ulogic_vector) return wishbone_addr_type;
function wb_to_addr(wb_addr: wishbone_addr_type) return std_ulogic_vector;
type wishbone_master_out is record
adr : wishbone_addr_type;
dat : wishbone_data_type;
@ -38,6 +41,7 @@ package wishbone_types is
--
-- IO Bus to a device, 30-bit address, 32-bits data
--
type wb_io_master_out is record
adr : std_ulogic_vector(29 downto 0);
dat : std_ulogic_vector(31 downto 0);
@ -56,3 +60,19 @@ package wishbone_types is
end record;
constant wb_io_slave_out_init : wb_io_slave_out := (ack => '0', stall => '0', others => (others => '0'));
end package wishbone_types;
package body wishbone_types is
function addr_to_wb(addr: std_ulogic_vector) return wishbone_addr_type is
begin
assert addr'length >= (wishbone_addr_type'length + wishbone_log2_width);
assert addr'right = 0;
return addr(wishbone_addr_type'left + wishbone_log2_width downto wishbone_log2_width);
end;
function wb_to_addr(wb_addr: wishbone_addr_type) return std_ulogic_vector is
variable ret : std_ulogic_vector(63 downto 0);
begin
ret := (others => '0');
ret(wishbone_addr_type'left + wishbone_log2_width downto wishbone_log2_width) := wb_addr;
return ret;
end;
end wishbone_types;