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[clocking] Bound SimplePllConfiguration by maximum reference freq

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David Biancolin
2020-11-02 10:38:37 -08:00
parent 946a191221
commit f387634a41
1 changed files with 3 additions and 2 deletions
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5
generators/chipyard/src/main/scala/clocking/DividerOnlyClockGenerator.scala
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@@ -16,12 +16,13 @@ import scala.collection.immutable.ListMap
object FrequencyUtils { object FrequencyUtils {
def computeReferenceFrequencyMHz( def computeReferenceFrequencyMHz(
requestedOutputs: Seq[ClockParameters], requestedOutputs: Seq[ClockParameters],
maximumAllowableDivisor: Int = 0xFFFF): ClockParameters = { maximumAllowableFreqMHz: Double = 8000.0): ClockParameters = {
require(requestedOutputs.nonEmpty) require(requestedOutputs.nonEmpty)
require(!requestedOutputs.contains(0.0)) require(!requestedOutputs.contains(0.0))
val freqs = requestedOutputs.map(f => BigInt(Math.round(f.freqMHz * 1000 * 1000))) val freqs = requestedOutputs.map(f => BigInt(Math.round(f.freqMHz * 1000 * 1000)))
val refFreq = freqs.reduce((a, b) => a * b / a.gcd(b)).toDouble / (1000 * 1000) val refFreq = freqs.reduce((a, b) => a * b / a.gcd(b)).toDouble / (1000 * 1000)
assert((refFreq / freqs.min.toDouble) < maximumAllowableDivisor.toDouble) assert(refFreq < maximumAllowableFreqMHz,
s"Reference frequency ${refFreq} exceeds maximum allowable value of ${maximumAllowableFreqMHz} MHz")
ClockParameters(refFreq) ClockParameters(refFreq)
} }
} }