Support consuming PMP number and granularity from DTB

The feature itself isn't implemented yet.

riscv/processor.cc

@@ -43,6 +43,8 @@ processor_t::processor_t(const char* isa, const char* priv, const char* varch,
     for (auto disasm_insn : ext->get_disasms())
       disassembler->add_insn(disasm_insn);
 
+  set_pmp_granularity(1 << PMP_SHIFT);
+  set_pmp_num(state.max_pmp);
   reset();
 }
 
@@ -440,6 +442,26 @@ static int ctz(reg_t val)
   return res;
 }
 
+void processor_t::set_pmp_num(reg_t n)
+{
+  // check the number of pmp is in a reasonable range
+  if (n > state.max_pmp) {
+    fprintf(stderr, "error: bad number of pmp regions: '%ld' from the dtb\n", (unsigned long)n);
+    abort();
+  }
+  n_pmp = n;
+}
+
+void processor_t::set_pmp_granularity(reg_t gran) {
+  // check the pmp granularity is set from dtb(!=0) and is power of 2
+  if (gran < (1 << PMP_SHIFT) || (gran & (gran - 1)) != 0) {
+    fprintf(stderr, "error: bad pmp granularity '%ld' from the dtb\n", (unsigned long)gran);
+    abort();
+  }
+
+  lg_pmp_granularity = ctz(gran);
+}
+
 void processor_t::take_interrupt(reg_t pending_interrupts)
 {
   reg_t mie = get_field(state.mstatus, MSTATUS_MIE);

riscv/processor.h

@@ -389,6 +389,9 @@ public:
 
   void trigger_updated();
 
+  void set_pmp_num(reg_t pmp_num);
+  void set_pmp_granularity(reg_t pmp_granularity);
+
 private:
   simif_t* sim;
   mmu_t* mmu; // main memory is always accessed via the mmu
@@ -434,6 +437,9 @@ private:
 
   // Track repeated executions for processor_t::disasm()
   uint64_t last_pc, last_bits, executions;
+  reg_t n_pmp;
+  reg_t lg_pmp_granularity;
+
 public:
   class vectorUnit_t {
     public:

riscv/sim.cc

@@ -89,6 +89,15 @@ sim_t::sim_t(const char* isa, const char* priv, const char* varch,
   } else {
     bus.add_device(clint_base, clint.get());
   }
+
+  for (size_t i = 0; i < nprocs; i++) {
+    reg_t pmp_num = 0, pmp_granularity = 0;
+    fdt_parse_pmp_num((void *)dtb.c_str(), &pmp_num, "riscv");
+    fdt_parse_pmp_alignment((void *)dtb.c_str(), &pmp_granularity, "riscv");
+
+    procs[i]->set_pmp_num(pmp_num);
+    procs[i]->set_pmp_granularity(pmp_granularity);
+  }
 }
 
 sim_t::~sim_t()