Fix handling of enter and space in developer screens.

At DEV screen:
- Space triggers TONORM
- Enter is ignored unless new GBB flag is set

At TONORM screen:
- Enter always means YES
- Space is ignored

So, if you hold the space key at the dev screen, you'll go to tonorm
and stay there until you press Enter or Esc.  If you hold the Enter
key at the dev screen, nothing will happen.

Add a GBB flag to allow Enter to trigger the TONORM screen; this will
be used by FAFT testing.

BRANCH=all
BUG=chrome-os-partner:12699
TEST=manual

1. press enter at dev screen.  nothing happens.
2. press space at dev screen.  tonorm.
3. press space at tonorm.  nothing happens.
4. press enter at tonorm.  turns off dev mode.

Change-Id: I9f3128d5114e1486911cc4d76d0ccd5649de1680
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/30456
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>

firmware/lib/vboot_api_kernel.c

@@ -105,35 +105,6 @@ uint32_t VbTryLoadKernel(VbCommonParams* cparams, LoadKernelParams* p,
   return retval;
 }
 
-/* Flush the keyboard buffer. */
-static VbError_t FlushKeyboard(void) {
-
-  int loops = 0;
-
-  /* Wait half a second to see if any keys are pressed.  If keys are
-   * auto-repeating, they'll repeat by then. */
-  VbExSleepMs(500);
-
-  /* If no keys are pressed, no need for any subsequent delay. */
-  if (!VbExKeyboardRead())
-    return VBERROR_SUCCESS;
-
-  /* Otherwise, wait 2 sec after the last key is pressed. */
-  VBDEBUG(("Keys held down at start of screen; flushing...\n"));
-  do {
-    if (VbExIsShutdownRequested())
-      return VBERROR_SHUTDOWN_REQUESTED;
-
-    VbExSleepMs(250);
-    loops++;
-    if (VbExKeyboardRead())
-      loops = 0;
-  } while (loops < 8);
-  VBDEBUG(("...done flushing.\n"));
-
-  return VBERROR_SUCCESS;
-}
-
 /* Ask the user to confirm something. We should display whatever the question
  * is first, then call this. ESC is always "no", ENTER is always "yes", and
  * we'll specify what SPACE means. We don't return until one of those keys is
@@ -141,14 +112,10 @@ static VbError_t FlushKeyboard(void) {
  *
  * Returns: 1=yes, 0=no, -1 = shutdown.
  */
-static int VbUserConfirms(VbCommonParams* cparams, int space_returns_this) {
+static int VbUserConfirms(VbCommonParams* cparams, int space_means_no) {
   uint32_t key;
 
-  VBDEBUG(("Entering %s(%d)\n", __func__, space_returns_this));
-
-  /* Flush any pending keystrokes */
-  if (FlushKeyboard() == VBERROR_SHUTDOWN_REQUESTED)
-    return -1;
+  VBDEBUG(("Entering %s(%d)\n", __func__, space_means_no));
 
   /* Await further instructions */
   while (1) {
@@ -160,14 +127,15 @@ static int VbUserConfirms(VbCommonParams* cparams, int space_returns_this) {
       VBDEBUG(("%s() - Yes (1)\n", __func__));
       return 1;
       break;
+    case ' ':
+      VBDEBUG(("%s() - Space (%s)\n", __func__, space_means_no));
+      if (space_means_no)
+        return 0;
+      break;
     case 0x1b:
       VBDEBUG(("%s() - No (0)\n", __func__));
       return 0;
       break;
-    case ' ':
-      VBDEBUG(("%s() - Space (%s)\n", __func__, space_returns_this));
-      return space_returns_this;
-      break;
     default:
       VbCheckDisplayKey(cparams, key, &vnc);
     }
@@ -202,10 +170,6 @@ VbError_t VbBootDeveloper(VbCommonParams* cparams, LoadKernelParams* p) {
   /* Show the dev mode warning screen */
   VbDisplayScreen(cparams, VB_SCREEN_DEVELOPER_WARNING, 0, &vnc);
 
-  /* Flush any pending keystrokes */
-  if (FlushKeyboard() == VBERROR_SHUTDOWN_REQUESTED)
-    return VBERROR_SHUTDOWN_REQUESTED;
-
   /* Get audio/delay context */
   audio = VbAudioOpen(cparams);
 
@@ -225,6 +189,9 @@ VbError_t VbBootDeveloper(VbCommonParams* cparams, LoadKernelParams* p) {
         /* nothing pressed */
         break;
       case '\r':
+        /* Enter only disables the virtual dev switch if allowed by GBB */
+        if (!(gbb->flags & GBB_FLAG_ENTER_TRIGGERS_TONORM))
+          break;
       case ' ':
       case 0x1B:
         /* See if we should disable the virtual dev-mode switch. */
@@ -233,7 +200,7 @@ VbError_t VbBootDeveloper(VbCommonParams* cparams, LoadKernelParams* p) {
             shared->flags & VBSD_BOOT_DEV_SWITCH_ON) {
           VbAudioClose(audio);    /* Stop the countdown while we go ask... */
           VbDisplayScreen(cparams, VB_SCREEN_DEVELOPER_TO_NORM, 0, &vnc);
-          switch (VbUserConfirms(cparams, 1)) { /* SPACE means yes */
+          switch (VbUserConfirms(cparams, 0)) { /* Ignore space */
           case 1:
             VBDEBUG(("%s() - leaving dev-mode...\n", __func__));
             VbNvSet(&vnc, VBNV_DISABLE_DEV_REQUEST, 1);
@@ -315,7 +282,6 @@ VbError_t VbBootRecovery(VbCommonParams* cparams, LoadKernelParams* p) {
   VbSharedDataHeader* shared = (VbSharedDataHeader*)cparams->shared_data_blob;
   uint32_t retval;
   uint32_t key;
-  int kb_flushed = 0;
   int i;
 
   VBDEBUG(("VbBootRecovery() start\n"));
@@ -345,13 +311,6 @@ VbError_t VbBootRecovery(VbCommonParams* cparams, LoadKernelParams* p) {
 
       VbDisplayScreen(cparams, VB_SCREEN_RECOVERY_REMOVE, 0, &vnc);
 
-      /* Flush any pending keystrokes */
-      if (!kb_flushed) {
-        if (FlushKeyboard() == VBERROR_SHUTDOWN_REQUESTED)
-          return VBERROR_SHUTDOWN_REQUESTED;
-        kb_flushed = 1;
-      }
-
       /* Scan keyboard more frequently than media, since x86 platforms
        * don't like to scan USB too rapidly. */
       for (i = 0; i < 4; i++) {
@@ -380,13 +339,6 @@ VbError_t VbBootRecovery(VbCommonParams* cparams, LoadKernelParams* p) {
                     VB_SCREEN_RECOVERY_INSERT : VB_SCREEN_RECOVERY_NO_GOOD,
                     0, &vnc);
 
-    /* Flush any pending keystrokes */
-    if (!kb_flushed) {
-      if (FlushKeyboard() == VBERROR_SHUTDOWN_REQUESTED)
-        return VBERROR_SHUTDOWN_REQUESTED;
-      kb_flushed = 1;
-    }
-
     /* Scan keyboard more frequently than media, since x86 platforms don't like
      * to scan USB too rapidly. */
     for (i = 0; i < 4; i++) {
@@ -399,7 +351,7 @@ VbError_t VbBootRecovery(VbCommonParams* cparams, LoadKernelParams* p) {
           VbExTrustEC()) {                             /* EC isn't pwned */
         /* Ask the user to confirm entering dev-mode */
         VbDisplayScreen(cparams, VB_SCREEN_RECOVERY_TO_DEV, 0, &vnc);
-        switch (VbUserConfirms(cparams, 0)) { /* SPACE means no */
+        switch (VbUserConfirms(cparams, 1)) { /* SPACE means no */
         case 1:
           VBDEBUG(("%s() - Enabling dev-mode...\n", __func__));
           if (TPM_SUCCESS != SetVirtualDevMode(1))