meta-phosphor: Add option to disable u-boot shell

For security, u-boot shell needs to be disabled. Setting the
CONFIG_BOOTDELAY to -2 will disable the prompt for entering into shell.

-1  will skip executing the commands.
>=0 will prompt to enter shell.
-2  will skip the prompt.

https://github.com/u-boot/u-boot/blob/51aef405550e603ff702c034f0e2cd0f15bdf2bb/common/autoboot.c#L479

Making it configurable through DISTRO_FEATURES.
Add "disable-u-boot-shell" to DISTRO_FEATURES for this feature.

Signed-off-by: Vivekanand Veeracholan <vveerach@google.com>
Change-Id: I1b1e1a6c2552335b13fb3f1a9561d08f3a0e8f94
diff --git a/meta-phosphor/aspeed-layer/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend b/meta-phosphor/aspeed-layer/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend
index 452ef7e..6ae4b1b 100644
--- a/meta-phosphor/aspeed-layer/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend
+++ b/meta-phosphor/aspeed-layer/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend
@@ -1,3 +1,4 @@
 FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
 
 require u-boot-aspeed.inc
+require recipes-bsp/u-boot/u-boot-obmc.inc
diff --git a/meta-phosphor/nuvoton-layer/recipes-bsp/u-boot/u-boot-nuvoton_%.bbappend b/meta-phosphor/nuvoton-layer/recipes-bsp/u-boot/u-boot-nuvoton_%.bbappend
new file mode 100644
index 0000000..ab57dad
--- /dev/null
+++ b/meta-phosphor/nuvoton-layer/recipes-bsp/u-boot/u-boot-nuvoton_%.bbappend
@@ -0,0 +1 @@
+require recipes-bsp/u-boot/u-boot-obmc.inc
diff --git a/meta-phosphor/recipes-bsp/u-boot/files/disable-u-boot-shell.cfg b/meta-phosphor/recipes-bsp/u-boot/files/disable-u-boot-shell.cfg
new file mode 100644
index 0000000..8876eb2
--- /dev/null
+++ b/meta-phosphor/recipes-bsp/u-boot/files/disable-u-boot-shell.cfg
@@ -0,0 +1,2 @@
+# Setting boot delay to -2 disables entering into U-boot shell
+CONFIG_BOOTDELAY=-2
diff --git a/meta-phosphor/recipes-bsp/u-boot/u-boot-obmc.inc b/meta-phosphor/recipes-bsp/u-boot/u-boot-obmc.inc
new file mode 100644
index 0000000..47529af
--- /dev/null
+++ b/meta-phosphor/recipes-bsp/u-boot/u-boot-obmc.inc
@@ -0,0 +1,5 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI:append = '${@bb.utils.contains_any("DISTRO_FEATURES", "disable-u-boot-shell", \
+    " file://disable-u-boot-shell.cfg", \
+    "", d)}'