library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; library work; use work.decode_types.all; use work.common.all; use work.insn_helpers.all; use work.helpers.all; -- 2 cycle LSU -- We calculate the address in the first cycle entity loadstore1 is generic ( HAS_FPU : boolean := true; -- Non-zero to enable log data collection LOG_LENGTH : natural := 0 ); port ( clk : in std_ulogic; rst : in std_ulogic; l_in : in Execute1ToLoadstore1Type; e_out : out Loadstore1ToExecute1Type; l_out : out Loadstore1ToWritebackType; d_out : out Loadstore1ToDcacheType; d_in : in DcacheToLoadstore1Type; m_out : out Loadstore1ToMmuType; m_in : in MmuToLoadstore1Type; dc_stall : in std_ulogic; log_out : out std_ulogic_vector(9 downto 0) ); end loadstore1; -- Note, we don't currently use the stall output from the dcache because -- we know it can take two requests without stalling when idle, we are -- its only user, and we know it never stalls when idle. architecture behave of loadstore1 is -- State machine for unaligned loads/stores type state_t is (IDLE, -- ready for instruction SECOND_REQ, -- send 2nd request of unaligned xfer ACK_WAIT, -- waiting for ack from dcache MMU_LOOKUP, -- waiting for MMU to look up translation TLBIE_WAIT, -- waiting for MMU to finish doing a tlbie FINISH_LFS, -- write back converted SP data for lfs* COMPLETE -- extra cycle to complete an operation ); type byte_index_t is array(0 to 7) of unsigned(2 downto 0); subtype byte_trim_t is std_ulogic_vector(1 downto 0); type trim_ctl_t is array(0 to 7) of byte_trim_t; type reg_stage_t is record -- latch most of the input request load : std_ulogic; tlbie : std_ulogic; dcbz : std_ulogic; addr : std_ulogic_vector(63 downto 0); store_data : std_ulogic_vector(63 downto 0); load_data : std_ulogic_vector(63 downto 0); write_reg : gspr_index_t; length : std_ulogic_vector(3 downto 0); byte_reverse : std_ulogic; byte_offset : unsigned(2 downto 0); brev_mask : unsigned(2 downto 0); sign_extend : std_ulogic; update : std_ulogic; update_reg : gpr_index_t; xerc : xer_common_t; reserve : std_ulogic; atomic : std_ulogic; atomic_last : std_ulogic; rc : std_ulogic; nc : std_ulogic; -- non-cacheable access virt_mode : std_ulogic; priv_mode : std_ulogic; state : state_t; dwords_done : std_ulogic; last_dword : std_ulogic; first_bytes : std_ulogic_vector(7 downto 0); second_bytes : std_ulogic_vector(7 downto 0); dar : std_ulogic_vector(63 downto 0); dsisr : std_ulogic_vector(31 downto 0); instr_fault : std_ulogic; align_intr : std_ulogic; sprval : std_ulogic_vector(63 downto 0); busy : std_ulogic; wait_dcache : std_ulogic; wait_mmu : std_ulogic; do_update : std_ulogic; extra_cycle : std_ulogic; mode_32bit : std_ulogic; byte_index : byte_index_t; use_second : std_ulogic_vector(7 downto 0); trim_ctl : trim_ctl_t; load_sp : std_ulogic; ld_sp_data : std_ulogic_vector(31 downto 0); ld_sp_nz : std_ulogic; ld_sp_lz : std_ulogic_vector(5 downto 0); wr_sel : std_ulogic_vector(1 downto 0); end record; signal r, rin : reg_stage_t; signal lsu_sum : std_ulogic_vector(63 downto 0); signal store_sp_data : std_ulogic_vector(31 downto 0); signal load_dp_data : std_ulogic_vector(63 downto 0); -- Generate byte enables from sizes function length_to_sel(length : in std_logic_vector(3 downto 0)) return std_ulogic_vector is begin case length is when "0001" => return "00000001"; when "0010" => return "00000011"; when "0100" => return "00001111"; when "1000" => return "11111111"; when others => return "00000000"; end case; end function length_to_sel; -- Calculate byte enables -- This returns 16 bits, giving the select signals for two transfers, -- to account for unaligned loads or stores function xfer_data_sel(size : in std_logic_vector(3 downto 0); address : in std_logic_vector(2 downto 0)) return std_ulogic_vector is variable longsel : std_ulogic_vector(15 downto 0); begin longsel := "00000000" & length_to_sel(size); return std_ulogic_vector(shift_left(unsigned(longsel), to_integer(unsigned(address)))); end function xfer_data_sel; -- 23-bit right shifter for DP -> SP float conversions function shifter_23r(frac: std_ulogic_vector(22 downto 0); shift: unsigned(4 downto 0)) return std_ulogic_vector is variable fs1 : std_ulogic_vector(22 downto 0); variable fs2 : std_ulogic_vector(22 downto 0); begin case shift(1 downto 0) is when "00" => fs1 := frac; when "01" => fs1 := '0' & frac(22 downto 1); when "10" => fs1 := "00" & frac(22 downto 2); when others => fs1 := "000" & frac(22 downto 3); end case; case shift(4 downto 2) is when "000" => fs2 := fs1; when "001" => fs2 := x"0" & fs1(22 downto 4); when "010" => fs2 := x"00" & fs1(22 downto 8); when "011" => fs2 := x"000" & fs1(22 downto 12); when "100" => fs2 := x"0000" & fs1(22 downto 16); when others => fs2 := x"00000" & fs1(22 downto 20); end case; return fs2; end; -- 23-bit left shifter for SP -> DP float conversions function shifter_23l(frac: std_ulogic_vector(22 downto 0); shift: unsigned(4 downto 0)) return std_ulogic_vector is variable fs1 : std_ulogic_vector(22 downto 0); variable fs2 : std_ulogic_vector(22 downto 0); begin case shift(1 downto 0) is when "00" => fs1 := frac; when "01" => fs1 := frac(21 downto 0) & '0'; when "10" => fs1 := frac(20 downto 0) & "00"; when others => fs1 := frac(19 downto 0) & "000"; end case; case shift(4 downto 2) is when "000" => fs2 := fs1; when "001" => fs2 := fs1(18 downto 0) & x"0" ; when "010" => fs2 := fs1(14 downto 0) & x"00"; when "011" => fs2 := fs1(10 downto 0) & x"000"; when "100" => fs2 := fs1(6 downto 0) & x"0000"; when others => fs2 := fs1(2 downto 0) & x"00000"; end case; return fs2; end; begin -- Calculate the address in the first cycle lsu_sum <= std_ulogic_vector(unsigned(l_in.addr1) + unsigned(l_in.addr2)) when l_in.valid = '1' else (others => '0'); loadstore1_0: process(clk) begin if rising_edge(clk) then if rst = '1' then r.state <= IDLE; r.busy <= '0'; r.do_update <= '0'; else r <= rin; end if; end if; end process; ls_fp_conv: if HAS_FPU generate -- Convert DP data to SP for stfs dp_to_sp: process(all) variable exp : unsigned(10 downto 0); variable frac : std_ulogic_vector(22 downto 0); variable shift : unsigned(4 downto 0); begin store_sp_data(31) <= l_in.data(63); store_sp_data(30 downto 0) <= (others => '0'); exp := unsigned(l_in.data(62 downto 52)); if exp > 896 then store_sp_data(30) <= l_in.data(62); store_sp_data(29 downto 0) <= l_in.data(58 downto 29); elsif exp >= 874 then -- denormalization required frac := '1' & l_in.data(51 downto 30); shift := 0 - exp(4 downto 0); store_sp_data(22 downto 0) <= shifter_23r(frac, shift); end if; end process; -- Convert SP data to DP for lfs sp_to_dp: process(all) variable exp : unsigned(7 downto 0); variable exp_dp : unsigned(10 downto 0); variable exp_nz : std_ulogic; variable exp_ao : std_ulogic; variable frac : std_ulogic_vector(22 downto 0); variable frac_shift : unsigned(4 downto 0); begin frac := r.ld_sp_data(22 downto 0); exp := unsigned(r.ld_sp_data(30 downto 23)); exp_nz := or (r.ld_sp_data(30 downto 23)); exp_ao := and (r.ld_sp_data(30 downto 23)); frac_shift := (others => '0'); if exp_ao = '1' then exp_dp := to_unsigned(2047, 11); -- infinity or NaN elsif exp_nz = '1' then exp_dp := 896 + resize(exp, 11); -- finite normalized value elsif r.ld_sp_nz = '0' then exp_dp := to_unsigned(0, 11); -- zero else -- denormalized SP operand, need to normalize exp_dp := 896 - resize(unsigned(r.ld_sp_lz), 11); frac_shift := unsigned(r.ld_sp_lz(4 downto 0)) + 1; end if; load_dp_data(63) <= r.ld_sp_data(31); load_dp_data(62 downto 52) <= std_ulogic_vector(exp_dp); load_dp_data(51 downto 29) <= shifter_23l(frac, frac_shift); load_dp_data(28 downto 0) <= (others => '0'); end process; end generate; loadstore1_1: process(all) variable v : reg_stage_t; variable brev_lenm1 : unsigned(2 downto 0); variable byte_offset : unsigned(2 downto 0); variable j : integer; variable k : unsigned(2 downto 0); variable kk : unsigned(3 downto 0); variable long_sel : std_ulogic_vector(15 downto 0); variable byte_sel : std_ulogic_vector(7 downto 0); variable req : std_ulogic; variable busy : std_ulogic; variable addr : std_ulogic_vector(63 downto 0); variable maddr : std_ulogic_vector(63 downto 0); variable wdata : std_ulogic_vector(63 downto 0); variable write_enable : std_ulogic; variable do_update : std_ulogic; variable done : std_ulogic; variable data_permuted : std_ulogic_vector(63 downto 0); variable data_trimmed : std_ulogic_vector(63 downto 0); variable store_data : std_ulogic_vector(63 downto 0); variable byte_rev : std_ulogic; variable length : std_ulogic_vector(3 downto 0); variable negative : std_ulogic; variable sprn : std_ulogic_vector(9 downto 0); variable exception : std_ulogic; variable next_addr : std_ulogic_vector(63 downto 0); variable mmureq : std_ulogic; variable dsisr : std_ulogic_vector(31 downto 0); variable mmu_mtspr : std_ulogic; variable itlb_fault : std_ulogic; variable misaligned : std_ulogic; begin v := r; req := '0'; mmu_mtspr := '0'; itlb_fault := '0'; sprn := std_ulogic_vector(to_unsigned(decode_spr_num(l_in.insn), 10)); dsisr := (others => '0'); mmureq := '0'; v.wr_sel := "11"; write_enable := '0'; do_update := r.do_update; v.do_update := '0'; -- load data formatting -- shift and byte-reverse data bytes for i in 0 to 7 loop j := to_integer(r.byte_index(i)) * 8; data_permuted(i * 8 + 7 downto i * 8) := d_in.data(j + 7 downto j); end loop; -- Work out the sign bit for sign extension. -- For unaligned loads crossing two dwords, the sign bit is in the -- first dword for big-endian (byte_reverse = 1), or the second dword -- for little-endian. if r.dwords_done = '1' and r.byte_reverse = '1' then negative := (r.length(3) and r.load_data(63)) or (r.length(2) and r.load_data(31)) or (r.length(1) and r.load_data(15)) or (r.length(0) and r.load_data(7)); else negative := (r.length(3) and data_permuted(63)) or (r.length(2) and data_permuted(31)) or (r.length(1) and data_permuted(15)) or (r.length(0) and data_permuted(7)); end if; -- trim and sign-extend for i in 0 to 7 loop case r.trim_ctl(i) is when "11" => data_trimmed(i * 8 + 7 downto i * 8) := r.load_data(i * 8 + 7 downto i * 8); when "10" => data_trimmed(i * 8 + 7 downto i * 8) := data_permuted(i * 8 + 7 downto i * 8); when "01" => data_trimmed(i * 8 + 7 downto i * 8) := (others => negative); when others => data_trimmed(i * 8 + 7 downto i * 8) := x"00"; end case; end loop; if HAS_FPU then -- Single-precision FP conversion for loads v.ld_sp_data := data_trimmed(31 downto 0); v.ld_sp_nz := or (data_trimmed(22 downto 0)); v.ld_sp_lz := count_left_zeroes(data_trimmed(22 downto 0)); end if; -- Byte reversing and rotating for stores. -- Done in the second cycle (the cycle after l_in.valid = 1). for i in 0 to 7 loop k := (to_unsigned(i, 3) - r.byte_offset) xor r.brev_mask; j := to_integer(k) * 8; store_data(i * 8 + 7 downto i * 8) := r.store_data(j + 7 downto j); end loop; -- compute (addr + 8) & ~7 for the second doubleword when unaligned next_addr := std_ulogic_vector(unsigned(r.addr(63 downto 3)) + 1) & "000"; -- 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 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 done := '1'; end if; exception := '0'; if r.dwords_done = '1' or r.state = SECOND_REQ then addr := next_addr; byte_sel := r.second_bytes; else addr := r.addr; byte_sel := r.first_bytes; end if; if r.mode_32bit = '1' then addr(63 downto 32) := (others => '0'); end if; maddr := addr; case r.state is when IDLE => when SECOND_REQ => req := '1'; v.state := ACK_WAIT; v.last_dword := '0'; when ACK_WAIT => -- r.wr_sel gets set one cycle after we come into ACK_WAIT state, -- which is OK because the dcache always takes at least two cycles. if r.update = '1' and (r.load = '0' or (HAS_FPU and r.load_sp = '1')) then v.wr_sel := "01"; end if; if d_in.error = '1' then -- dcache will discard the second request if it -- gets an error on the 1st of two requests if d_in.cache_paradox = '1' then -- signal an interrupt straight away exception := '1'; dsisr(63 - 38) := not r.load; -- XXX there is no architected bit for this dsisr(63 - 35) := d_in.cache_paradox; else -- Look up the translation for TLB miss -- and also for permission error and RC error -- in case the PTE has been updated. mmureq := '1'; v.state := MMU_LOOKUP; end if; end if; if d_in.valid = '1' then if r.last_dword = '0' then v.dwords_done := '1'; v.last_dword := '1'; if r.load = '1' then v.load_data := data_permuted; end if; else write_enable := r.load and not r.load_sp; if HAS_FPU and r.load_sp = '1' then -- SP to DP conversion takes a cycle -- Write back rA update in this cycle if needed do_update := r.update; v.wr_sel := "10"; v.state := FINISH_LFS; elsif r.extra_cycle = '1' then -- loads with rA update need an extra cycle v.wr_sel := "01"; 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 m_in.done = '1' then if r.instr_fault = '0' then -- retry the request now that the MMU has installed a TLB entry req := '1'; if r.last_dword = '0' then v.state := SECOND_REQ; else v.state := ACK_WAIT; end if; end if; end if; if m_in.err = '1' then exception := '1'; dsisr(63 - 33) := m_in.invalid; dsisr(63 - 36) := m_in.perm_error; dsisr(63 - 38) := not r.load; dsisr(63 - 44) := m_in.badtree; dsisr(63 - 45) := m_in.rc_error; end if; when TLBIE_WAIT => when FINISH_LFS => when COMPLETE => exception := r.align_intr; 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 if l_in.valid = '1' then v.mode_32bit := l_in.mode_32bit; v.load := '0'; v.dcbz := '0'; v.tlbie := '0'; v.instr_fault := '0'; v.align_intr := '0'; v.dwords_done := '0'; v.last_dword := '1'; v.write_reg := l_in.write_reg; v.length := l_in.length; v.byte_reverse := l_in.byte_reverse; v.sign_extend := l_in.sign_extend; v.update := l_in.update; v.update_reg := l_in.update_reg; v.xerc := l_in.xerc; v.reserve := l_in.reserve; v.rc := l_in.rc; v.nc := l_in.ci; v.virt_mode := l_in.virt_mode; v.priv_mode := l_in.priv_mode; v.load_sp := '0'; v.wait_dcache := '0'; v.wait_mmu := '0'; v.do_update := '0'; v.extra_cycle := '0'; if HAS_FPU and l_in.is_32bit = '1' then v.store_data := x"00000000" & store_sp_data; else v.store_data := l_in.data; end if; addr := lsu_sum; if l_in.second = '1' then -- for the second half of a 16-byte transfer, use next_addr addr := next_addr; end if; if l_in.mode_32bit = '1' then addr(63 downto 32) := (others => '0'); end if; v.addr := addr; 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. if addr(31 downto 28) = "1100" and l_in.virt_mode = '0' then v.nc := '1'; end if; if l_in.second = '0' then -- Do length_to_sel and work out if we are doing 2 dwords long_sel := xfer_data_sel(l_in.length, lsu_sum(2 downto 0)); byte_sel := long_sel(7 downto 0); v.first_bytes := byte_sel; v.second_bytes := long_sel(15 downto 8); else byte_sel := r.first_bytes; long_sel := r.second_bytes & r.first_bytes; end if; -- check alignment for larx/stcx misaligned := or (std_ulogic_vector(unsigned(l_in.length(2 downto 0)) - 1) and addr(2 downto 0)); v.align_intr := l_in.reserve and misaligned; if l_in.repeat = '1' and l_in.second = '0' and addr(3) = '1' then -- length is really 16 not 8 -- Make misaligned lq cause an alignment interrupt in LE mode, -- in order to avoid the case with RA = RT + 1 where the second half -- faults but the first doesn't (and updates RT+1, destroying RA). -- The equivalent BE case doesn't occur because RA = RT is illegal. misaligned := '1'; if l_in.reserve = '1' or (l_in.op = OP_LOAD and l_in.byte_reverse = '0') then v.align_intr := '1'; end if; end if; v.atomic := not misaligned; v.atomic_last := not misaligned and (l_in.second or not l_in.repeat); case l_in.op is when OP_STORE => req := '1'; when OP_LOAD => req := '1'; v.load := '1'; -- Allow an extra cycle for RA update on loads v.extra_cycle := l_in.update; if HAS_FPU and l_in.is_32bit = '1' then -- Allow an extra cycle for SP->DP precision conversion v.load_sp := '1'; v.extra_cycle := '1'; end if; when OP_DCBZ => v.align_intr := v.nc; req := '1'; v.dcbz := '1'; when OP_TLBIE => mmureq := '1'; v.tlbie := '1'; v.state := TLBIE_WAIT; v.wait_mmu := '1'; when OP_MFSPR => v.wr_sel := "00"; -- partial decode on SPR number should be adequate given -- the restricted set that get sent down this path if sprn(9) = '0' and sprn(5) = '0' then if sprn(0) = '0' then v.sprval := x"00000000" & r.dsisr; else v.sprval := r.dar; end if; else -- reading one of the SPRs in the MMU v.sprval := m_in.sprval; end if; v.state := COMPLETE; when OP_MTSPR => if sprn(9) = '0' and sprn(5) = '0' then if sprn(0) = '0' then v.dsisr := l_in.data(31 downto 0); else v.dar := l_in.data; end if; 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 maddr := l_in.nia; 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; if req = '1' then if v.align_intr = '1' then v.state := COMPLETE; elsif long_sel(15 downto 8) = "00000000" then v.state := ACK_WAIT; else v.state := SECOND_REQ; end if; end if; v.busy := req or mmureq or mmu_mtspr; end if; -- Work out controls for store formatting if l_in.valid = '1' then byte_offset := unsigned(lsu_sum(2 downto 0)); byte_rev := l_in.byte_reverse; length := l_in.length; brev_lenm1 := "000"; if byte_rev = '1' then brev_lenm1 := unsigned(length(2 downto 0)) - 1; end if; v.byte_offset := byte_offset; v.brev_mask := brev_lenm1; end if; -- Work out load formatter controls for next cycle byte_offset := unsigned(v.addr(2 downto 0)); brev_lenm1 := "000"; if v.byte_reverse = '1' then brev_lenm1 := unsigned(v.length(2 downto 0)) - 1; end if; for i in 0 to 7 loop kk := ('0' & (to_unsigned(i, 3) xor brev_lenm1)) + ('0' & byte_offset); v.use_second(i) := kk(3); v.byte_index(i) := kk(2 downto 0); end loop; for i in 0 to 7 loop if i < to_integer(unsigned(v.length)) then if v.dwords_done = '1' then v.trim_ctl(i) := '1' & not v.use_second(i); else v.trim_ctl(i) := "10"; end if; else v.trim_ctl(i) := '0' & v.sign_extend; end if; end loop; -- Update outputs to dcache d_out.valid <= req and not v.align_intr; d_out.load <= v.load; d_out.dcbz <= v.dcbz; d_out.nc <= v.nc; d_out.reserve <= v.reserve; d_out.atomic <= v.atomic; d_out.atomic_last <= v.atomic_last; d_out.addr <= addr; d_out.data <= store_data; d_out.byte_sel <= byte_sel; d_out.virt_mode <= v.virt_mode; d_out.priv_mode <= v.priv_mode; -- Update outputs to MMU m_out.valid <= mmureq; m_out.iside <= v.instr_fault; m_out.load <= r.load; m_out.priv <= r.priv_mode; m_out.tlbie <= v.tlbie; m_out.mtspr <= mmu_mtspr; m_out.sprn <= sprn; m_out.addr <= maddr; m_out.slbia <= l_in.insn(7); m_out.rs <= l_in.data; -- Update outputs to writeback -- Multiplex either cache data to the destination GPR or -- the address for the rA update. l_out.valid <= done; case r.wr_sel is when "00" => l_out.write_enable <= '1'; l_out.write_reg <= r.write_reg; l_out.write_data <= r.sprval; when "01" => l_out.write_enable <= do_update; l_out.write_reg <= gpr_to_gspr(r.update_reg); l_out.write_data <= r.addr; when "10" => l_out.write_enable <= '1'; l_out.write_reg <= r.write_reg; l_out.write_data <= load_dp_data; when others => l_out.write_enable <= write_enable; l_out.write_reg <= r.write_reg; l_out.write_data <= data_trimmed; end case; l_out.xerc <= r.xerc; l_out.rc <= r.rc and done; l_out.store_done <= d_in.store_done; -- update exception info back to execute1 e_out.busy <= busy; e_out.exception <= exception; e_out.alignment <= r.align_intr; e_out.instr_fault <= r.instr_fault; e_out.invalid <= m_in.invalid; e_out.badtree <= m_in.badtree; e_out.perm_error <= m_in.perm_error; e_out.rc_error <= m_in.rc_error; e_out.segment_fault <= m_in.segerr; if exception = '1' and r.instr_fault = '0' then v.dar := addr; if m_in.segerr = '0' and r.align_intr = '0' then v.dsisr := dsisr; end if; end if; -- Update registers rin <= v; end process; l1_log: if LOG_LENGTH > 0 generate signal log_data : std_ulogic_vector(9 downto 0); begin ls1_log: process(clk) begin if rising_edge(clk) then log_data <= e_out.busy & e_out.exception & l_out.valid & m_out.valid & d_out.valid & m_in.done & r.dwords_done & std_ulogic_vector(to_unsigned(state_t'pos(r.state), 3)); end if; end process; log_out <= log_data; end generate; end;