On 15.02.2022 15:57, Sean Anderson wrote:
On 2/15/22 9:02 AM, Michal Simek wrote:
On 2/15/22 14:49, Rafał Miłecki wrote:
From: Rafał Miłecki rafal@milecki.pl
U-Boot uses environment variables for storing device setup data on flash. That data usually needs to be accessed by a bootloader, kernel and often user-space.
This binding allows describing environment data location and its format clearly. In some/many cases it should be cleaner than hardcoding & duplicating that info in multiple places. Bootloader & kernel can share DTS and user-space can try reading it too or just have correct data exposed by a kernel.
Signed-off-by: Rafał Miłecki rafal@milecki.pl
.../devicetree/bindings/nvmem/u-boot,env.yaml | 58 +++++++++++++++++++ MAINTAINERS | 5 ++ 2 files changed, 63 insertions(+) create mode 100644 Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
diff --git a/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml new file mode 100644 index 000000000000..a2b3a9b88eb8 --- /dev/null +++ b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml @@ -0,0 +1,58 @@ +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/nvmem/u-boot,env.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml#
+title: U-Boot environment variables
+description: | + U-Boot uses environment variables to store device parameters and + configuration. They may be used for booting process, setup or keeping end user + info.
+ Data is stored on flash in a U-Boot specific format (header and NUL separated + key-value pairs).
+ This binding allows specifying data location and used format.
+maintainers: + - Rafał Miłecki rafal@milecki.pl
+allOf: + - $ref: nvmem.yaml#
+properties: + compatible: + oneOf: + - description: A standalone env data block + const: u-boot,env + - description: Two redundant blocks with active one flagged + const: u-boot,env-redundant-bool + - description: Two redundant blocks with active having higher counter + const: u-boot,env-redundant-count
I am not convinced that this is the best way how to do it. Because in u-boot implementation you would have to enable MTD partitions to get there. And the whole parsing will take a lot of time.
I think the way how I think this can be handled is.
# I don't think that discussion with Simon was finished. But for example (chosen or firmware node) chosen { u-boot { u-boot,env = <&qspi &part0>; u-boot,env-redundant = <&qspi &part1>; #or u-boot,env = <&qspi 0 40000>; u-boot,env-redundant = <&qspi 40000 40000>;
What about when the environment is on top of UBI?
We can always add support for binding UBI volumes in DT. Somethig more-or-less like:
partitions { compatible = "fixed-partitions"; #address-cells = <1>; #size-cells = <1>;
partition@0 { compatible = "ubi"; label = "ubi"; reg = <0x0 0x1000000>;
env0: partition-0 { volume-name = "env"; };
env1: partition-1 { volume-id = <10>; }; }; };