riscv: replace rtc device with a real clint implementation

1 files changed, 72 insertions, 0 deletions

diff --git a/riscv/clint.cc b/riscv/clint.cc
new file mode 100644
index 0000000..08508b4
--- /dev/null
+++ b/riscv/clint.cc
@@ -0,0 +1,72 @@
+#include "devices.h"
+#include "processor.h"
+
+clint_t::clint_t(std::vector<processor_t*>& procs)
+  : procs(procs), mtimecmp(procs.size())
+{
+}
+
+/* 0000 msip hart 0
+ * 0004 msip hart 1
+ * 4000 mtimecmp hart 0 lo
+ * 4004 mtimecmp hart 0 hi
+ * 4008 mtimecmp hart 1 lo
+ * 400c mtimecmp hart 1 hi
+ * bff8 mtime lo
+ * bffc mtime hi
+ */
+
+#define MSIP_BASE	0x0
+#define MTIMECMP_BASE	0x4000
+#define MTIME_BASE	0xbff8
+
+bool clint_t::load(reg_t addr, size_t len, uint8_t* bytes)
+{
+  if (addr >= MSIP_BASE && addr + len <= MSIP_BASE + procs.size()*sizeof(msip_t)) {
+    std::vector<msip_t> msip(procs.size());
+    for (size_t i = 0; i < procs.size(); ++i)
+      msip[i] = !!(procs[i]->state.mip & MIP_MSIP);
+    memcpy(bytes, (uint8_t*)&msip[0] + addr - MSIP_BASE, len);
+  } else if (addr >= MTIMECMP_BASE && addr + len <= MTIMECMP_BASE + procs.size()*sizeof(mtimecmp_t)) {
+    memcpy(bytes, (uint8_t*)&mtimecmp[0] + addr - MTIMECMP_BASE, len);
+  } else if (addr >= MTIME_BASE && addr + len <= MTIME_BASE + sizeof(mtime_t)) {
+    memcpy(bytes, (uint8_t*)&mtime + addr - MTIME_BASE, len);
+  } else {
+    return false;
+  }
+  return true;
+}
+
+bool clint_t::store(reg_t addr, size_t len, const uint8_t* bytes)
+{
+  if (addr >= MSIP_BASE && addr + len <= MSIP_BASE + procs.size()*sizeof(msip_t)) {
+    std::vector<msip_t> msip(procs.size());
+    std::vector<msip_t> mask(procs.size(), 0);
+    memcpy((uint8_t*)&msip[0] + addr - MSIP_BASE, bytes, len);
+    memset((uint8_t*)&mask[0] + addr - MSIP_BASE, 0xff, len);
+    for (size_t i = 0; i < procs.size(); ++i) {
+      if (!(mask[i] & 0xFF)) continue;
+      procs[i]->state.mip &= ~MIP_MSIP;
+      if (!!(msip[i] & 1))
+        procs[i]->state.mip |= MIP_MSIP;
+    }
+  } else if (addr >= MTIMECMP_BASE && addr + len <= MTIMECMP_BASE + procs.size()*sizeof(mtimecmp_t)) {
+    memcpy((uint8_t*)&mtimecmp[0] + addr - MTIMECMP_BASE, bytes, len);
+  } else if (addr >= MTIME_BASE && addr + len <= MTIME_BASE + sizeof(mtime_t)) {
+    memcpy((uint8_t*)&mtime + addr - MTIME_BASE, bytes, len);
+  } else {
+    return false;
+  }
+  increment(0);
+  return true;
+}
+
+void clint_t::increment(reg_t inc)
+{
+  mtime += inc;
+  for (size_t i = 0; i < procs.size(); i++) {
+    procs[i]->state.mip &= ~MIP_MTIP;
+    if (mtime >= mtimecmp[i])
+      procs[i]->state.mip |= MIP_MTIP;
+  }
+}