tegra124: Skip display init when vboot says we don't need it.

If EFS is enabled and vboot didn't tell us it's going to use the display, we
can skip initializing it and save some boot time.

BUG=chrome-os-partner:27094
TEST=Built and booted on nyan without EFS in recovery mode and normal mode.
Built and booted on nyan with EFS in recovery mode and normal mode. Verified
that in normal mode with EFS the display initialization was skipped and boot
time was essentially the same as when display initialization was simply
commented out.
BRANCH=None

Change-Id: I1e2842b57a38061f40514407c8fab1e38b75be80
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/192544
Reviewed-by: Tom Warren <twarren@nvidia.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>

src/soc/nvidia/tegra124/soc.c

@@ -26,6 +26,7 @@
 #include <soc/nvidia/tegra124/sdram.h>
 #include "chip.h"
 #include <soc/display.h>
+#include <vendorcode/google/chromeos/chromeos.h>
 
 /* this sucks, but for now, fb size/location are hardcoded.
  * Will break if we get 2. Sigh.
@@ -50,7 +51,10 @@ static void soc_enable(device_t dev)
 
 static void soc_init(device_t dev)
 {
-	display_startup(dev);
+	if (vboot_skip_display_init())
+		printk(BIOS_INFO, "Skipping display init.\n");
+	else
+		display_startup(dev);
 	printk(BIOS_INFO, "CPU: Tegra124\n");
 }
 

src/vendorcode/google/chromeos/chromeos.c

@@ -83,6 +83,22 @@ int recovery_mode_enabled(void)
 		vboot_enable_recovery();
 }
 
+int vboot_skip_display_init(void)
+{
+#if CONFIG_VBOOT_VERIFY_FIRMWARE
+	struct vboot_handoff *vbho;
+
+	vbho = cbmem_find(CBMEM_ID_VBOOT_HANDOFF);
+
+	if (vbho == NULL)
+		return 0;
+
+	return !(vbho->init_params.out_flags & VB_INIT_OUT_ENABLE_DISPLAY);
+#else
+	return 0;
+#endif
+}
+
 #ifdef __PRE_RAM__
 void __attribute__((weak)) save_chromeos_gpios(void)
 {

src/vendorcode/google/chromeos/chromeos.h

@@ -42,6 +42,7 @@ void save_vbnv(const uint8_t *vbnv_copy);
 /* functions implemented in chromeos.c: */
 int developer_mode_enabled(void);
 int recovery_mode_enabled(void);
+int vboot_skip_display_init(void);
 
 /* functions implemented in vboot.c */
 void init_chromeos(int bootmode);