input: Provide a board specific mechanism to decide whether to skip i8042 init

This change adds a board overridable function which can be used to decide
whether or not to initialize the i8042 keyboard controller. On systems where
it isn't actually connected to anything, this can save a significant amount of
boot time.

On Stumpy, this saves about 200ms on boot.

Signed-off-by: Gabe Black <gabeblack@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@ti.com>

drivers/input/i8042.c

@@ -26,6 +26,7 @@
 /* includes */
 
 #include <common.h>
+#include <linux/compiler.h>
 
 #ifdef CONFIG_USE_CPCIDVI
 extern u8 gt_cpcidvi_in8(u32 offset);
@@ -320,6 +321,16 @@ static int kbd_controller_present(void)
 	return in8(I8042_STATUS_REG) != 0xff;
 }
 
+/*
+ * Implement a weak default function for boards that optionally
+ * need to skip the i8042 initialization.
+ */
+int __weak board_i8042_skip(void)
+{
+	/* As default, don't skip */
+	return 0;
+}
+
 /*******************************************************************************
  *
  * i8042_kbd_init - reset keyboard and init state flags
@@ -329,7 +340,7 @@ int i8042_kbd_init(void)
 	int keymap, try;
 	char *penv;
 
-	if (!kbd_controller_present())
+	if (!kbd_controller_present() || board_i8042_skip())
 		return -1;
 
 #ifdef CONFIG_USE_CPCIDVI