examples/touchscreen: Add a configuration option to indicate that there is or is not an architecture-specific initialization function

ChangeLog.txt

@@ -884,4 +884,5 @@
 	  three smaller files (2014-4-11).
 	* apps/netutils/ntpclient/ntpclient.c: Corrections to the NTP client
 	  from Manuel Stuehn (2014-4-12).
-
+	* apps/examples/touchscreen:  Add a configuration option to indicate if
+	  architecture-specific initialized is required, yes or no (2014-4-14).

examples/touchscreen/Kconfig

@@ -43,4 +43,25 @@ config EXAMPLES_TOUCHSCREEN_MOUSE
 		The touchscreen test can also be configured to work with a mouse
 		driver by setting this option.
 
+config EXAMPLES_TOUCHSCREEN_ARCHINIT
+	bool "Architecture-specific initialization"
+	default y
+	---help---
+		By default, the touchscreen example will call arch_tcinitialize() to
+		register the touchscreen device before it attempts to open it.
+		Similarly, it will call arch_tcuninitialize() to unregister the
+		touchscreen device when it is finished.
+
+		This works well for the typical touchscreen controller but there are
+		other devices that cannot be initialized and uninitialized in this
+		fashion.  Consider a USB mouse, fo example.  The USB mouse will be
+		registered when the mouse is connected and unregistered when the
+		mouse is disconnected.
+
+		So, in cases like this, there are two options:  (1) provide dummy
+		arch_tcinitialize() and arch_tcuninitialize() just to satisfy the
+		linking requirements or, (2) select this option.  if this option is
+		de-selected, then the arch_tcinitialize() and arch_tcuninitialize() will
+		never be called.
+
 endif

examples/touchscreen/tc_main.c

@@ -118,6 +118,7 @@ int tc_main(int argc, char *argv[])
   message("tc_main: nsamples: %d\n", CONFIG_EXAMPLES_TOUCHSCREEN_NSAMPLES);
 #endif
 
+#ifdef CONFIG_EXAMPLES_TOUCHSCREEN_ARCHINIT
   /* Initialization of the touchscreen hardware is performed by logic
    * external to this test.
    */
@@ -130,6 +131,7 @@ int tc_main(int argc, char *argv[])
       errval = 1;
       goto errout;
     }
+#endif
 
   /* Open the touchscreen device for reading */
 
@@ -249,8 +251,12 @@ int tc_main(int argc, char *argv[])
 
 errout_with_dev:
   close(fd);
+
 errout_with_tc:
+#ifdef CONFIG_EXAMPLES_TOUCHSCREEN_ARCHINIT
   arch_tcuninitialize();
+#endif
+
 errout:
   message("Terminating!\n");
   msgflush();