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rocket-chip/src/main/scala/uncore/tilelink2/RegMapper.scala

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// See LICENSE for license details.
package uncore.tilelink2
import Chisel._
// A bus agnostic register interface to a register-based device
case class RegMapperParams(indexBits: Int, maskBits: Int, extraBits: Int)
class RegMapperInput(params: RegMapperParams) extends GenericParameterizedBundle(params)
{
val read = Bool()
val index = UInt(width = params.indexBits)
val data = UInt(width = params.maskBits*8)
val mask = UInt(width = params.maskBits)
val extra = UInt(width = params.extraBits)
}
class RegMapperOutput(params: RegMapperParams) extends GenericParameterizedBundle(params)
{
val read = Bool()
val data = UInt(width = params.maskBits*8)
val extra = UInt(width = params.extraBits)
}
object RegMapper
{
// Create a generic register-based device
def apply(bytes: Int, concurrency: Option[Int], in: DecoupledIO[RegMapperInput], mapping: RegField.Map*) = {
val regmap = mapping.toList
require (!regmap.isEmpty)
// Ensure no register appears twice
regmap.combinations(2).foreach { case Seq((reg1, _), (reg2, _)) =>
require (reg1 != reg2)
}
// Flatten the regmap into (Reg:Int, Offset:Int, field:RegField)
val flat = regmap.map { case (reg, fields) =>
val offsets = fields.scanLeft(0)(_ + _.width).init
(offsets zip fields) map { case (o, f) => (reg, o, f) }
}.flatten
require (!flat.isEmpty)
val endIndex = 1 << log2Ceil(regmap.map(_._1).max+1)
val params = RegMapperParams(log2Up(endIndex), bytes, in.bits.params.extraBits)
val out = Wire(Decoupled(new RegMapperOutput(params)))
val front = Wire(Decoupled(new RegMapperInput(params)))
front.bits := in.bits
// Must this device pipeline the control channel?
val pipelined = flat.map(_._3.pipelined).reduce(_ || _)
val depth = concurrency.getOrElse(if (pipelined) 1 else 0)
require (depth >= 0)
require (!pipelined || depth > 0)
val back = if (depth > 0) Queue(front, depth, pipe = depth == 1) else front
// Forward declaration of all flow control signals
val rivalid = Wire(Vec(flat.size, Bool()))
val wivalid = Wire(Vec(flat.size, Bool()))
val riready = Wire(Vec(flat.size, Bool()))
val wiready = Wire(Vec(flat.size, Bool()))
val rovalid = Wire(Vec(flat.size, Bool()))
val wovalid = Wire(Vec(flat.size, Bool()))
val roready = Wire(Vec(flat.size, Bool()))
val woready = Wire(Vec(flat.size, Bool()))
// Per-register list of all control signals needed for data to flow
val rifire = Array.tabulate(endIndex) { i => Seq(Bool(true)) }
val wifire = Array.tabulate(endIndex) { i => Seq(Bool(true)) }
val rofire = Array.tabulate(endIndex) { i => Seq(Bool(true)) }
val wofire = Array.tabulate(endIndex) { i => Seq(Bool(true)) }
// The output values for each register
val dataOut = Array.tabulate(endIndex) { _ => UInt(0) }
// Which bits are touched?
val frontMask = FillInterleaved(8, front.bits.mask)
val backMask = FillInterleaved(8, back .bits.mask)
// Connect the fields
for (i <- 0 until flat.size) {
val (reg, low, field) = flat(i)
val high = low + field.width - 1
// Confirm that no register is too big
require (high < 8*bytes)
val rimask = frontMask(high, low).orR()
val wimask = frontMask(high, low).andR()
val romask = backMask(high, low).orR()
val womask = backMask(high, low).andR()
val data = if (field.write.combinational) back.bits.data else front.bits.data
val (f_riready, f_rovalid, f_data) = field.read.fn(rivalid(i) && rimask, roready(i) && romask)
val (f_wiready, f_wovalid) = field.write.fn(wivalid(i) && wimask, woready(i) && womask, data(high, low))
riready(i) := f_riready || !rimask
wiready(i) := f_wiready || !wimask
rovalid(i) := f_rovalid || !romask
wovalid(i) := f_wovalid || !womask
rifire(reg) = riready(i) +: rifire(reg)
wifire(reg) = wiready(i) +: wifire(reg)
rofire(reg) = rovalid(i) +: rofire(reg)
wofire(reg) = wovalid(i) +: wofire(reg)
dataOut(reg) = dataOut(reg) | ((f_data << low) & (~UInt(0, width = high+1)))
}
// Is the selected register ready?
val rifireMux = Vec(rifire.map(_.reduce(_ && _)))
val wifireMux = Vec(wifire.map(_.reduce(_ && _)))
val rofireMux = Vec(rofire.map(_.reduce(_ && _)))
val wofireMux = Vec(wofire.map(_.reduce(_ && _)))
val iready = Mux(front.bits.read, rifireMux(front.bits.index), wifireMux(front.bits.index))
val oready = Mux(back .bits.read, rofireMux(back .bits.index), wofireMux(back .bits.index))
// Connect the pipeline
in.ready := front.ready && iready
front.valid := in.valid && iready
back.ready := out.ready && oready
out.valid := back.valid && oready
// Which register is touched?
val frontSel = UIntToOH(front.bits.index)
val backSel = UIntToOH(back.bits.index)
// Include the per-register one-hot selected criteria
for (reg <- 0 until endIndex) {
rifire(reg) = (in.valid && front.ready && front.bits.read && frontSel(reg)) +: rifire(reg)
wifire(reg) = (in.valid && front.ready && !front.bits.read && frontSel(reg)) +: wifire(reg)
rofire(reg) = (back.valid && out.ready && back .bits.read && backSel (reg)) +: rofire(reg)
wofire(reg) = (back.valid && out.ready && !back .bits.read && backSel (reg)) +: wofire(reg)
}
// Connect the field's ivalid and oready
for (i <- 0 until flat.size) {
val (reg, _, _ ) = flat(i)
rivalid(i) := rifire(reg).filter(_ ne riready(i)).reduce(_ && _)
wivalid(i) := wifire(reg).filter(_ ne wiready(i)).reduce(_ && _)
roready(i) := rofire(reg).filter(_ ne rovalid(i)).reduce(_ && _)
woready(i) := wofire(reg).filter(_ ne wovalid(i)).reduce(_ && _)
}
out.bits.read := back.bits.read
out.bits.data := Vec(dataOut)(back.bits.index)
out.bits.extra := back.bits.extra
(endIndex, out)
}
}