On Wed, Mar 09, 2022 at 02:42:43PM +0100, Michal Simek wrote: > > > On 2/28/22 14:12, Rafał Miłecki wrote: > > From: Rafał Miłecki <rafal@xxxxxxxxxx> > > > > U-Boot uses environment variables for storing device setup data. It > > usually needs to be accessed by a bootloader, kernel and often > > user-space. > > > > This binding allows describing environment data located in a raw flash > > partition. It's treated as NVMEM device and can be reused later for > > other storage devices. > > > > Using DT should be cleaner than hardcoding & duplicating such 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. > > > > A custom "compatible" string allows system to automatically load > > relevant NVMEM driver but phandle can be also used for reading raw > > location. > > > > Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx> > > --- > > V2: Update descriptions to don't make this binding MTD (flash partition) > > specific. Mention multiple possible storage ways. > > V3: Drop > > allOf: > > - $ref: nvmem.yaml# > > as we don't use anything rom the nvmem.yaml. Thanks Rob. > > --- > > .../devicetree/bindings/nvmem/u-boot,env.yaml | 62 +++++++++++++++++++ > > MAINTAINERS | 5 ++ > > 2 files changed, 67 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/nvmem/u-boot,env.yaml > > > > diff --git a/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml > > new file mode 100644 > > index 000000000000..e70b2a60cb9a > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml > > @@ -0,0 +1,62 @@ > > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause > > +%YAML 1.2 > > +--- > > +$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 using U-Boot specific formats (variant specific header and NUL > > + separated key-value pairs). > > + > > + Environment data can be stored on various storage entities, e.g.: > > + 1. Raw flash partition > > + 2. UBI volume > > + > > + This binding allows marking storage device (as containing env data) and > > + specifying used format. > > + > > + Right now only flash partition case is covered but it may be extended to e.g. > > + UBI volumes in the future. > > + > > +maintainers: > > + - Rafał Miłecki <rafal@xxxxxxxxxx> > > + > > +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 > > + > > + reg: > > + maxItems: 1 > > + > > +additionalProperties: false > > + > > +examples: > > + - | > > + partitions { > > + compatible = "fixed-partitions"; > > + #address-cells = <1>; > > + #size-cells = <1>; > > + > > + partition@0 { > > + reg = <0x0 0x40000>; > > + label = "u-boot"; > > + read-only; > > + }; > > + > > + env: partition@40000 { > > + compatible = "u-boot,env"; > > + reg = <0x40000 0x10000>; > > + }; > > + }; > > diff --git a/MAINTAINERS b/MAINTAINERS > > index db8052bc1d26..24fc181a7e6c 100644 > > --- a/MAINTAINERS > > +++ b/MAINTAINERS > > @@ -19958,6 +19958,11 @@ W: http://linuxtv.org > > T: git git://linuxtv.org/media_tree.git > > F: drivers/media/pci/tw686x/ > > +U-BOOT ENVIRONMENT VARIABLES > > +M: Rafał Miłecki <rafal@xxxxxxxxxx> > > +S: Maintained > > +F: Documentation/devicetree/bindings/nvmem/u-boot,env.yaml > > + > > UACCE ACCELERATOR FRAMEWORK > > M: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx> > > M: Zhou Wang <wangzhou1@xxxxxxxxxxxxx> > > I think that parsing these partitions is quite sw intensive process and I > can't still see the value to have compatible string here. It's always good to know what a node represents. > I would prefer to have just any link from u-boot node to partition instead. That's a separate issue and having 'compatible' in no way disallows that. Rob
