[PATCH] dt-bindings: u-boot: Add a few more options bindings

[Simon Glass <sjg@chromium.org>]

This adds three new options with varying degree of interest / precedent.

This being sent to the mailing list since it might attract more review.
A PR will be sent when this has had some review. That is why the file
path is set up for https://github.com/devicetree-org/dt-schema rather
than the Linux kernel.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

 schemas/options/u-boot.yaml | 51 +++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/schemas/options/u-boot.yaml b/schemas/options/u-boot.yaml
index 71dfda7..b8bdec1 100644
--- a/schemas/options/u-boot.yaml
+++ b/schemas/options/u-boot.yaml
@@ -71,6 +71,37 @@ properties:
       2: use simplified command line (e.g. avoid hush)
       3... reserved
 
+  load-environment:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 1
+    maximum: 1
+    description: |
+      This allows control over whether U-Boot loads its environment after
+      relocation. This normally happens automatically, but can pose a security
+      risk, so disabling it in certain situations is useful.
+
+      Note: This could be a boolean. It is defined as an integer since that
+      allows changing the value without resizing the devicetree. I'm not sure
+      how ugly that is, but IMO the fact that 'false' boolean values are
+      represented by being missing is a bit of a pain. One must either add or
+      delete the property.
+
+      Values:
+
+      0: don't load the environment
+      1: do load the environment
+
+  no-apm-final:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: |
+      For devices running on coreboot, this tells U-Boot not to lock down the
+      Intel Management Engine (ME) registers. This allows U-Boot to access the
+      hardware more fully for platforms that need it.
+
+      Absence of this property indicates that the ME registers should be locked
+      down as part of U-Boot's start-up sequence and before the command line is
+      available.
+
   silent-console:
     $ref: /schemas/types.yaml#/definitions/uint32
     default: 0
@@ -88,6 +119,23 @@ properties:
         enabled)
       2: console output is suppressed and not recorded
 
+  spl-payload-offset:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 0
+    description: |
+      If present (and SPL is controlled by the devicetree), this allows the
+      offset of the SPL payload (typically U-Boot) to be specified. The offset
+      is in bytes from the start of the media (typically SPI flash).
+
+      Note: This is quite widely used in U-Boot, but since v2018.01 it is
+      possible to use Binman instead, to provide this offset (and various
+      others) to SPL, or even to U-Boot proper. So far I have not tried sending
+      the Binman bindings upstream, but perhaps that should be done instead.
+
+      See here for details:
+
+      https://u-boot.readthedocs.io/en/latest/develop/package/binman.html#image-description-format
+
 required:
   - compatible
 
@@ -101,6 +149,9 @@ examples:
         bootcmd = "vboot go auto";
         bootdelay-sec = <(-1)>;
         bootsecure = <1>;
+        load-environment = <0>;
+        no-apm-final;
         silent-console = <1>;
+        spl-payload-offset = <0x40000>;   /* 256K */
       };
     };
-- 
2.34.0.rc2.393.gf8c9666880-goog