Feature proposal POC: DTB discovery feature

riscv/sim.cc

@@ -39,6 +39,7 @@ extern device_factory_t* ns16550_factory;
 sim_t::sim_t(const cfg_t *cfg, bool halted,
              std::vector<std::pair<reg_t, abstract_mem_t*>> mems,
              const std::vector<device_factory_sargs_t>& plugin_device_factories,
+             const bool dtb_discovery,
              const std::vector<std::string>& args,
              const debug_module_config_t &dm_config,
              const char *log_path,
@@ -49,6 +50,7 @@ sim_t::sim_t(const cfg_t *cfg, bool halted,
   : htif_t(args),
     cfg(cfg),
     mems(mems),
+    dtb_discovery(dtb_discovery),
     dtb_enabled(dtb_enabled),
     log_file(log_path),
     cmd_file(cmd_file),
@@ -242,6 +244,48 @@ sim_t::sim_t(const cfg_t *cfg, bool halted,
     cpu_idx++;
   }
 
+
+  std::vector<device_factory_sargs_t> plugin_device_auto_discovery_factories;
+  if (dtb_discovery)
+  {
+    // Iterate through all devices in the map
+    for (const auto &pair : mmio_device_map())
+    {
+      const std::string &device_name = pair.first;
+      int offset = -1;
+      // Find all instances of this device type
+      while ((offset = fdt_node_offset_by_compatible(fdt, offset, device_name.c_str())) >= 0)
+      {
+        // Get node name
+        const char *node_name = fdt_get_name(fdt, offset, NULL);
+
+        // Get params from spike_plugin_params dts field.
+        int spike_plugin_params_len;
+        const char* spike_plugin_params=(char*) fdt_getprop(fdt, offset, "spike,plugin-params", &spike_plugin_params_len); //todo: remove hard-coded "spike_plugin_params"
+
+        std::cout << "DTB discovered device: " << node_name << " - compatible with device type:" << device_name <<" - params: "<<spike_plugin_params<< std::endl;
+
+        //Extract params in the comma-separated format
+        const std::string device_args(spike_plugin_params);
+        std::vector<std::string> parsed_args;
+        std::stringstream sstr(device_args);
+        while (sstr.good())
+        {
+          std::string substr;
+          getline(sstr, substr, ',');
+          parsed_args.push_back(substr);
+        }
+
+        //Add device
+        plugin_device_auto_discovery_factories.push_back(std::make_pair(pair.second, parsed_args));
+      }
+    }
+  }
+
+  device_factories.insert(device_factories.end(),
+                          plugin_device_auto_discovery_factories.begin(),
+                          plugin_device_auto_discovery_factories.end());
+
   // must be located after procs/harts are set (devices might use sim_t get_* member functions)
   for (size_t i = 0; i < device_factories.size(); i++) {
     const device_factory_t* factory = device_factories[i].first;

riscv/sim.h

@@ -32,6 +32,7 @@ class sim_t : public htif_t, public simif_t
   sim_t(const cfg_t *cfg, bool halted,
         std::vector<std::pair<reg_t, abstract_mem_t*>> mems,
         const std::vector<device_factory_sargs_t>& plugin_device_factories,
+        const bool dtb_discovery,
         const std::vector<std::string>& args,
         const debug_module_config_t &dm_config, const char *log_path,
         bool dtb_enabled, const char *dtb_file,
@@ -78,6 +79,7 @@ class sim_t : public htif_t, public simif_t
   std::pair<reg_t, reg_t> initrd_range;
   std::string dts;
   std::string dtb;
+  const bool dtb_discovery;
   bool dtb_enabled;
   std::vector<std::shared_ptr<abstract_device_t>> devices;
   std::shared_ptr<clint_t> clint;

spike_main/spike.cc

@@ -54,6 +54,7 @@ static void help(int exit_code = 1)
   fprintf(stderr, "  --misaligned          Support misaligned memory accesses\n");
   fprintf(stderr, "  --device=<name>       Attach MMIO plugin device from an --extlib library,\n");
   fprintf(stderr, "                          specify --device=<name>,<args> to pass down extra args.\n");
+  fprintf(stderr, "  --dtb-discovery       Enable direct device discovery from device tree blob. Requires --dtb and usage of special \"spike_plugin_params\" dts field.\n");
   fprintf(stderr, "  --log-cache-miss      Generate a log of cache miss\n");
   fprintf(stderr, "  --log-commits         Generate a log of commits info\n");
   fprintf(stderr, "  --extension=<name>    Specify RoCC Extension\n");
@@ -325,6 +326,7 @@ int main(int argc, char** argv)
   bool UNUSED socket = false;  // command line option -s
   bool dump_dts = false;
   bool dtb_enabled = true;
+  bool dtb_discovery = false;
   const char* kernel = NULL;
   reg_t kernel_offset, kernel_size;
   std::vector<device_factory_sargs_t> plugin_device_factories;
@@ -397,6 +399,7 @@ int main(int argc, char** argv)
   parser.option(0, "pmpgranularity", 1, [&](const char* s){cfg.pmpgranularity = atoul_safe(s);});
   parser.option(0, "priv", 1, [&](const char* s){cfg.priv = s;});
   parser.option(0, "device", 1, device_parser);
+  parser.option(0, "dtb-discovery", 0, [&](const char UNUSED *s){ dtb_discovery = true;} );
   parser.option(0, "extension", 1, [&](const char* s){extensions.push_back(find_extension(s));});
   parser.option(0, "dump-dts", 0, [&](const char UNUSED *s){dump_dts = true;});
   parser.option(0, "disable-dtb", 0, [&](const char UNUSED *s){dtb_enabled = false;});
@@ -520,8 +523,18 @@ int main(int argc, char** argv)
     cfg.hartids = default_hartids;
   }
 
+  if (dtb_discovery && !plugin_device_factories.empty()) {
+      std::cerr << "--dtb-discovery option is not compatible with --device option.\n";
+      exit(1);
+  }
+
+  if (dtb_discovery && dtb_file==NULL) {
+      std::cerr << "--dtb-discovery option required a dtb_file. Use --dtb option.\n";
+      exit(1);
+  }
+
   sim_t s(&cfg, halted,
-      mems, plugin_device_factories, htif_args, dm_config, log_path, dtb_enabled, dtb_file,
+      mems, plugin_device_factories, dtb_discovery,  htif_args, dm_config, log_path, dtb_enabled, dtb_file,
       socket,
       cmd_file,
       instructions);