riscv/rocket-chip
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ahb: ignore hrdata on an AHB error

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From the AHB spec:
 "A slave only has to provide valid data when a transfer completes with an OKAY
  response. ERROR responses do not require valid read data."
This commit is contained in:
Wesley W. Terpstra 2017-10-30 18:07:25 -07:00
parent 6318d7d44c
commit 45a904b396
3 changed files with 14 additions and 4 deletions
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2
src/main/scala/amba/ahb/Test.scala
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@ -49,7 +49,7 @@ class AHBFuzzMaster(aFlow: Boolean, txns: Int)(implicit p: Parameters) extends L
{
val node = AHBIdentityNode()
val fuzz = LazyModule(new TLFuzzer(txns, overrideAddress = Some(fuzzAddr)))
val model = LazyModule(new TLRAMModel("AHBFuzzMaster"))
val model = LazyModule(new TLRAMModel("AHBFuzzMaster", ignoreErrorData=true))
(node
:= TLToAHB(aFlow)

9
src/main/scala/amba/ahb/ToTL.scala
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@ -106,7 +106,14 @@ class AHBToTL()(implicit p: Parameters) extends LazyModule
out.a.bits.mask := MaskGen(d_addr, d_size, beatBytes)
out.d.ready := d_recv // backpressure AccessAckData arriving faster than AHB beats
in.hrdata := out.d.bits.data
// NOTE: on error, we present the read result on the hreadyout LOW cycle
// This means that if you latch hrdata from an error, the result is garbage.
// To fix this would require a bus-wide register, and the AHB spec says this:
// "A slave only has to provide valid data when a transfer completes with an OKAY
// response. ERROR responses do not require valid read data."
// Therefore, we choose to accept this slight TL-AHB infidelity.
in.hrdata := out.d.bits.data
// In a perfect world, we'd use these signals
val hresp = d_error || (out.d.valid && out.d.bits.error)

7
src/main/scala/tilelink/RAMModel.scala
View File

@ -22,7 +22,7 @@ import freechips.rocketchip.util._
// put, get, getAck, putAck => ok: detected by getAck (it sees busy>0) impossible for FIFO
// If FIFO, the getAck should check data even if its validity was wiped
class TLRAMModel(log: String = "")(implicit p: Parameters) extends LazyModule
class TLRAMModel(log: String = "", ignoreErrorData: Boolean = false)(implicit p: Parameters) extends LazyModule
{
val node = TLAdapterNode()
@ -288,6 +288,8 @@ class TLRAMModel(log: String = "")(implicit p: Parameters) extends LazyModule
printf(", undefined (concurrent incomplete puts #%d)\n", d_inc(i) - d_dec(i))
} .elsewhen (!d_fifo && !d_valid) {
printf(", undefined (concurrent completed put)\n")
} .elsewhen (Bool(ignoreErrorData) && d.error) {
printf(", undefined (error result)\n")
} .otherwise {
printf("\n")
when (shadow.value =/= got) { printf("EXPECTED: 0x%x\n", shadow.value) }
@ -303,8 +305,9 @@ class TLRAMModel(log: String = "")(implicit p: Parameters) extends LazyModule
when ((Cat(race.reverse) & d_mask).orR) { d_no_race := Bool(false) }
when (d_last) {
val must_match = d_crc_valid && (d_fifo || (d_valid && d_no_race))
val error = Bool(ignoreErrorData) && d.error
printf(log + " crc = 0x%x %d\n", d_crc, must_match.asUInt)
when (must_match && d_crc =/= d_crc_check) { printf("EXPECTED: 0x%x\n", d_crc_check) }
when (!error && must_match && d_crc =/= d_crc_check) { printf("EXPECTED: 0x%x\n", d_crc_check) }
assert (!must_match || d_crc === d_crc_check)
}
}