Add cmdline --of-name option

Add an option for passing hwmon instances via the open firmware
device path.  This allows udev triggers based on the path.

Change-Id: Icffc9734208204a052dc2910500df88136590e7d
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/readd.cpp b/readd.cpp
index 1cc2894..8253d92 100644
--- a/readd.cpp
+++ b/readd.cpp
@@ -18,6 +18,7 @@
 #include "argument.hpp"
 #include "mainloop.hpp"
 #include "config.h"
+#include "sysfs.hpp"
 
 static void exit_with_error(const char* err, char** argv)
 {
@@ -33,10 +34,20 @@
     auto options = std::make_unique<ArgumentParser>(argc, argv);
 
     // Parse out path argument.
-    auto path = (*options)["path"];
+    auto path = (*options)["of-name"];
+    if (path != ArgumentParser::empty_string)
+    {
+        path = findHwmon(path);
+    }
+
     if (path == ArgumentParser::empty_string)
     {
-        exit_with_error("Path not specified.", argv);
+        path = (*options)["path"];
+    }
+
+    if (path == ArgumentParser::empty_string)
+    {
+        exit_with_error("Path not specified or invalid.", argv);
     }
 
     // Finished getting options out, so cleanup the parser.