@ -44,10 +44,9 @@ architecture behave of loadstore1 is
type state_t is (IDLE, -- ready for instruction
SECOND_REQ, -- send 2nd request of unaligned xfer
ACK_WAIT, -- waiting for ack from dcache
LD_UPDATE, -- writing rA with computed addr on load
MMU_LOOKUP, -- waiting for MMU to look up translation
TLBIE_WAIT, -- waiting for MMU to finish doing a tlbie
SPR_CMPLT -- complete a mf/tspr operation
COMPLETE -- extra cycle to complete an operation
);
type reg_stage_t is record
@ -83,6 +82,8 @@ architecture behave of loadstore1 is
busy : std_ulogic;
wait_dcache : std_ulogic;
wait_mmu : std_ulogic;
do_update : std_ulogic;
extra_cycle : std_ulogic;
end record;
type byte_sel_t is array(0 to 7) of std_ulogic;
@ -132,8 +133,7 @@ begin
if rst = '1' then
r.state <= IDLE;
r.busy <= '0';
r.wait_dcache <= '0';
r.wait_mmu <= '0';
r.do_update <= '0';
else
r <= rin;
end if;
@ -172,9 +172,6 @@ begin
begin
v := r;
req := '0';
byte_sel := (others => '0');
addr := lsu_sum;
maddr := l_in.addr2; -- address from RB for tlbie
v.mfspr := '0';
mmu_mtspr := '0';
itlb_fault := '0';
@ -183,7 +180,9 @@ begin
mmureq := '0';
write_enable := '0';
do_update := '0';
do_update := r.do_update;
v.do_update := '0';
-- load data formatting
byte_offset := unsigned(r.addr(2 downto 0));
@ -239,7 +238,8 @@ begin
-- Busy calculation.
-- We need to minimize the delay from clock to busy valid because it
-- gates the start of execution of the next instruction.
busy := r.busy or (r.wait_dcache and not d_in.valid) or (r.wait_mmu and not m_in.done);
busy := r.busy and not ((r.wait_dcache and d_in.valid) or (r.wait_mmu and m_in.done));
v.busy := busy;
done := '0';
if r.state /= IDLE and busy = '0' then
@ -247,12 +247,19 @@ begin
end if;
exception := '0';
if r.dwords_done = '1' or r.state = SECOND_REQ then
maddr := next_addr;
byte_sel := r.second_bytes;
else
maddr := r.addr;
byte_sel := r.first_bytes;
end if;
addr := maddr;
case r.state is
when IDLE =>
when SECOND_REQ =>
addr := next_addr;
byte_sel := r.second_bytes;
req := '1';
v.state := ACK_WAIT;
v.last_dword := '0';
@ -261,11 +268,6 @@ begin
if d_in.error = '1' then
-- dcache will discard the second request if it
-- gets an error on the 1st of two requests
if r.dwords_done = '1' then
maddr := next_addr;
else
maddr := r.addr;
end if;
if d_in.cache_paradox = '1' then
-- signal an interrupt straight away
exception := '1';
@ -289,24 +291,22 @@ begin
end if;
else
write_enable := r.load;
if r.load = '1' and r.update = '1' then
if r.extra_cycle = '1' then
-- loads with rA update need an extra cycle
v.state := LD_UPDATE;
v.state := COMPLETE;
v.do_update := r.update;
else
-- stores write back rA update in this cycle
do_update := r.update;
end if;
v.busy := '0';
end if;
end if;
-- r.wait_dcache gets set one cycle after we come into ACK_WAIT state,
-- which is OK because the dcache always takes at least two cycles.
v.wait_dcache := r.last_dword and not r.extra_cycle;
when MMU_LOOKUP =>
if r.dwords_done = '1' then
addr := next_addr;
byte_sel := r.second_bytes;
else
addr := r.addr;
byte_sel := r.first_bytes;
end if;
if m_in.done = '1' then
if r.instr_fault = '0' then
-- retry the request now that the MMU has installed a TLB entry
@ -329,15 +329,13 @@ begin
when TLBIE_WAIT =>
when LD_UPDATE =>
do_update := '1';
when SPR_CMPLT =>
when COMPLETE =>
end case;
if done = '1' or exception = '1' then
v.state := IDLE;
v.busy := '0';
end if;
-- Note that l_in.valid is gated with busy inside execute1
@ -361,6 +359,13 @@ begin
v.nc := l_in.ci;
v.virt_mode := l_in.virt_mode;
v.priv_mode := l_in.priv_mode;
v.wait_dcache := '0';
v.wait_mmu := '0';
v.do_update := '0';
v.extra_cycle := '0';
addr := lsu_sum;
maddr := l_in.addr2; -- address from RB for tlbie
-- XXX Temporary hack. Mark the op as non-cachable if the address
-- is the form 0xc------- for a real-mode access.
@ -392,6 +397,8 @@ begin
when OP_LOAD =>
req := '1';
v.load := '1';
-- Allow an extra cycle for RA update on loads
v.extra_cycle := l_in.update;
when OP_DCBZ =>
req := '1';
v.dcbz := '1';
@ -399,6 +406,7 @@ begin
mmureq := '1';
v.tlbie := '1';
v.state := TLBIE_WAIT;
v.wait_mmu := '1';
when OP_MFSPR =>
v.mfspr := '1';
-- partial decode on SPR number should be adequate given
@ -413,7 +421,7 @@ begin
-- reading one of the SPRs in the MMU
v.sprval := m_in.sprval;
end if;
v.state := SPR_CMPLT;
v.state := COMPLETE;
when OP_MTSPR =>
if sprn(9) = '0' and sprn(5) = '0' then
if sprn(0) = '0' then
@ -421,11 +429,12 @@ begin
else
v.dar := l_in.data;
end if;
v.state := SPR_CMPLT;
v.state := COMPLETE;
else
-- writing one of the SPRs in the MMU
mmu_mtspr := '1';
v.state := TLBIE_WAIT;
v.wait_mmu := '1';
end if;
when OP_FETCH_FAILED =>
-- send it to the MMU to do the radix walk
@ -433,6 +442,7 @@ begin
v.instr_fault := '1';
mmureq := '1';
v.state := MMU_LOOKUP;
v.wait_mmu := '1';
when others =>
assert false report "unknown op sent to loadstore1";
end case;
@ -444,32 +454,9 @@ begin
v.state := SECOND_REQ;
end if;
end if;
end if;
-- Work out whether we'll be busy next cycle
v.busy := '0';
v.wait_dcache := '0';
v.wait_mmu := '0';
case v.state is
when SECOND_REQ =>
v.busy := '1';
when ACK_WAIT =>
if v.last_dword = '0' or (v.load = '1' and v.update = '1') then
v.busy := '1';
else
v.wait_dcache := '1';
end if;
when MMU_LOOKUP =>
if v.instr_fault = '0' then
v.busy := '1';
else
v.wait_mmu := '1';
end if;
when TLBIE_WAIT =>
v.wait_mmu := '1';
when others =>
-- not busy next cycle
end case;
v.busy := req or mmureq or mmu_mtspr;
end if;
-- Update outputs to dcache
d_out.valid <= req;
