1 files changed, 113 insertions, 0 deletions
diff --git a/debug/risc-v-gsp-rm-vm/sim/devices/priscv.py b/debug/risc-v-gsp-rm-vm/sim/devices/priscv.py
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+"""RISC-V local (PRISCV) register block.
+
+Evidence kind: **hardware register/field header + observed access pattern.**
+
+Reached through the PRIV aperture at ``PRIV + 0x111000`` and through the libos
+kernel's private mapping at ``0x3_0000_1000`` (the firmware reads the trace
+and error-status registers there during boot).  Modelled registers:
+
+================================  ======  =====  ==============================
+register                          offset  access semantics
+================================  ======  =====  ==============================
+``RISCV_IRQMSET``                 0x2ac   W      ``irq_mask |= value``
+``RISCV_IRQMCLR``                 0x2b0   W      ``irq_mask &= ~value``
+``RISCV_IRQMASK``                 0x2b4   R      ``irq_mask``
+``RISCV_IRQDEST``                 0x2b8   RW     storage
+``RISCV_IRQTYPE``                 0x2bc   RW     storage
+``RISCV_TRACECTL``                0x344   RW     storage
+``RISCV_TRACE_RDIDX``             0x348   RW     storage
+``RISCV_TRACE_WTIDX``             0x34c   RW     storage
+``RISCV_PRIV_ERR_STAT``           0x360   RW     storage
+``RISCV_HUB_ERR_STAT``            0x36c   RW     storage
+================================  ======  =====  ==============================
+
+The IRQ mask semantics (set/clear/read) follow the header access types and the
+observed boot reads; core interrupt *delivery* (mtvec/mip) is not part of this
+device and remains unmodelled (documented unknown).
+"""
+from __future__ import annotations
+
+from .base import Device
+
+IRQMSET = 0x2AC
+IRQMCLR = 0x2B0
+IRQMASK = 0x2B4
+IRQDEST = 0x2B8
+IRQTYPE = 0x2BC
+TRACECTL = 0x344
+TRACE_RDIDX = 0x348
+TRACE_WTIDX = 0x34C
+PRIV_ERR_STAT = 0x360
+PRIV_ERR_INFO = 0x364
+PRIV_ERR_ADDR = 0x368
+HUB_ERR_STAT = 0x36C
+
+_RW = {IRQDEST, IRQTYPE, TRACECTL, TRACE_RDIDX, TRACE_WTIDX,
+       PRIV_ERR_STAT, HUB_ERR_STAT}
+#: Read-only error capture registers (header R-I4R); the boot panic path
+#: reads them after a trap (observed reads at PC 0x40106BC).
+_RO = {PRIV_ERR_INFO, PRIV_ERR_ADDR}
+
+
+class PriscvBlock(Device):
+    """RISC-V-local control/trace/error registers."""
+
+    name = "priscv"
+
+    def __init__(self, *, base: int = 0, size: int = 0x1000):
+        super().__init__(base=base, size=size)
+        self.reset()
+
+    def reset(self) -> None:
+        self.irq_mask = 0
+        self.regs: dict[int, int] = {off: 0 for off in _RW}
+        self.error: dict[int, int] = {off: 0 for off in _RO}
+
+    def read(self, offset: int, size: int) -> int | None:
+        if size != 4:
+            return None
+        if offset == IRQMASK:
+            return self.irq_mask
+        if offset in self.regs:
+            return self.regs[offset]
+        if offset in self.error:
+            return self.error[offset]
+        return None
+
+    def write(self, offset: int, size: int, value: int) -> bool:
+        if size != 4:
+            return False
+        value &= 0xFFFFFFFF
+        if offset == IRQMSET:
+            self.irq_mask = (self.irq_mask | value) & 0xFFFFFFFF
+            return True
+        if offset == IRQMCLR:
+            self.irq_mask = (self.irq_mask & ~value) & 0xFFFFFFFF
+            return True
+        if offset == IRQMASK:
+            return False  # read-only
+        if offset in self.regs:
+            self.regs[offset] = value
+            return True
+        return False
+
+    def peek(self, offset: int, size: int) -> int | None:
+        if size != 4:
+            return None
+        if offset == IRQMASK:
+            return self.irq_mask
+        if offset in self.error:
+            return self.error[offset]
+        return self.regs.get(offset)
+
+    def state(self) -> dict:
+        return {"irq_mask": self.irq_mask,
+                "regs": {str(k): v for k, v in sorted(self.regs.items())},
+                "error": {str(k): v for k, v in sorted(self.error.items())}}
+
+    def load_state(self, data: dict) -> None:
+        self.irq_mask = int(data.get("irq_mask", 0))
+        regs = {int(k): int(v) for k, v in data.get("regs", {}).items()}
+        self.regs = {off: regs.get(off, 0) for off in _RW}
+        err = {int(k): int(v) for k, v in data.get("error", {}).items()}
+        self.error = {off: err.get(off, 0) for off in _RO}