Add the possibility to have an architecture specific ctrlc() function.

This allows us to return immediately in ctrlc() on sandbox and thus
not slow down network througput.

arch/sandbox/lib/common.c

@@ -97,9 +97,7 @@ int linux_tstc(int fd)
 	/*
 	 * We set the timeout here to 100us, because otherwise
 	 * U-Boot would eat all cpu resources while waiting
-	 * for input. On the other hand this makes some
-	 * things like networking slow, because U-Boot will
-	 * poll this function very often.
+	 * for input. 
 	 */
 	ret = select(fd + 1, &rfds, NULL, NULL, &tv);
 
@@ -109,6 +107,15 @@ int linux_tstc(int fd)
 	return 0;
 }
 
+int ctrlc(void)
+{
+	char chr;
+
+	if (linux_read_nonblock(0, &chr, 1) == 1 && chr == 3)
+		return 1;
+	return 0;
+}
+
 int linux_getc(void)
 {
 	char ret;

common/console.c

@@ -357,6 +357,7 @@ int vprintf (const char *fmt, va_list args)
 }
 EXPORT_SYMBOL(vprintf);
 
+#ifndef ARCH_HAS_CTRLC
 /* test if ctrl-c was pressed */
 int ctrlc (void)
 {
@@ -365,6 +366,7 @@ int ctrlc (void)
 	return 0;
 }
 EXPORT_SYMBOL(ctrlc);
+#endif /* ARCH_HAS_CTRC */
 
 #ifdef CONFIG_HAS_EARLY_INIT
 

include/asm-sandbox/common.h

@@ -1 +1,6 @@
-/* nothing */
+#ifndef ASM_COMMON_H
+#define ASM_COMMON_H
+
+#define ARCH_HAS_CTRLC
+
+#endif /* ASM_COMMON_H */