From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 8 Sep 2020 13:05:13 +0000 (+0100)
Subject: argh, somehow EINT check got moved out of if/elif block
X-Git-Tag: semi_working_ecp5~126
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a7bf25865a70088e96fabdd68c6a565c86196b88;p=soc.git

argh, somehow EINT check got moved out of if/elif block
---

diff --git a/src/soc/decoder/power_decoder2.py b/src/soc/decoder/power_decoder2.py
index 9ab81a7f..389c98b5 100644
--- a/src/soc/decoder/power_decoder2.py
+++ b/src/soc/decoder/power_decoder2.py
@@ -826,10 +826,18 @@ class PowerDecode2(PowerDecodeSubset):
             # everything including destroying read of RA and RB.
             comb += self.do_copy("trapaddr", 0x70) # strip first nibble
 
+        ####################
+        # ok so the instruction's been decoded, blah blah, however
+        # now we need to determine if it's actually going to go ahead...
+        # *or* if in fact it's a privileged operation, whether there's
+        # an external interrupt, etc. etc.  this is a simple priority
+        # if-elif-elif sequence.  decrement takes highest priority,
+        # EINT next highest, privileged operation third.
+
         # check if instruction is privileged
         is_priv_insn = instr_is_priv(m, op.internal_op, e.do.insn)
 
-        # different trap conditions
+        # different IRQ conditions
         ext_irq_ok = Signal()
         dec_irq_ok = Signal()
         priv_ok = Signal()
@@ -840,14 +848,14 @@ class PowerDecode2(PowerDecodeSubset):
         comb += priv_ok.eq(is_priv_insn & msr[MSR.PR])
         comb += illeg_ok.eq(op.internal_op == MicrOp.OP_ILLEGAL)
 
-        # external interrupt? only if MSR.EE set
-        with m.If(ext_irq_ok):
-            self.trap(m, TT.EINT, 0x500)
-
         # decrement counter (v3.0B p1099): TODO 32-bit version (MSR.LPCR)
         with m.If(dec_irq_ok):
             self.trap(m, TT.DEC, 0x900)   # v3.0B 6.5 p1065
 
+        # external interrupt? only if MSR.EE set
+        with m.Elif(ext_irq_ok):
+            self.trap(m, TT.EINT, 0x500)
+
         # privileged instruction trap
         with m.Elif(priv_ok):
             self.trap(m, TT.PRIV, 0x700)
@@ -864,6 +872,9 @@ class PowerDecode2(PowerDecodeSubset):
         with m.Else():
             comb += e_out.eq(e)
 
+        ####################
+        # follow-up after trap/irq to set up SRR0/1
+
         # trap: (note e.insn_type so this includes OP_ILLEGAL) set up fast regs
         # Note: OP_SC could actually be modified to just be a trap
         with m.If((do_out.insn_type == MicrOp.OP_TRAP) |