Re: [PATCH v5 06/11] nvmem: Add bindings for simple nvmem framework

[Srinivas Kandagatla]

On 16/06/15 23:53, Stephen Boyd wrote:
> On 05/21/2015 09:44 AM, Srinivas Kandagatla wrote:
> > diff --git a/Documentation/devicetree/bindings/nvmem/nvmem.txt b/Documentation/devicetree/bindings/nvmem/nvmem.txt
> > new file mode 100644
> > index 0000000..ecea654
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/nvmem/nvmem.txt
> > @@ -0,0 +1,84 @@
> > += NVMEM Data Device Tree Bindings =
> > +
> > +This binding is intended to represent the location of hardware
> > +configuration data stored in NVMEMs.
>
> It would be worthwhile spelling out what NVMEM stands for.
>
> > +
> > +On a significant proportion of boards, the manufacturer has stored
> > +some data on NVMEM, for the OS to be able to retrieve these information
> > +and act upon it. Obviously, the OS has to know about where to retrieve
> > +these data from, and where they are stored on the storage device.
> > +
> > +This document is here to document this.
> > +
> > += Data providers =
> > +Contains bindings specific to provider drivers and data cells as children
> > +to this node.
>
> children of this node?
Yep, will fix the text
> > +
> > +Optional properties:
> > + read-only: Mark the provider as read only.
> > +
> > += Data cells =
> > +These are the child nodes of the provider which contain data cell
> > +information like offset and size in nvmem provider.
> > +
> > +Required properties:
> > +reg:	specifies the offset in byte within that storage device, start bit
> > +	in the byte and the length in bits of the data we care about.
> > +	There could be more then one offset-length pairs in this property.
>
> s/then/than/
Yep.
> > +
> > +Optional properties:
> > +
> > +bit-offset: specifies the offset in bit within the address range specified
> > +	by reg property. Can take values from 0-7.
> > +nbits: specifies number of bits this cell occupies starting from bit-offset.
> > +
>
> Hopefully the consumer knows the endianness of the data stored.

As we read byte-byte, does it matter, as long as consumer gets them in 
the same order as its stored.


> > +For example:
> > +
> > +	/* Provider */
> > +	qfprom: qfprom@00700000 {
> > +		...
> > +
> > +		/* Data cells */
> > +		tsens_calibration: calib@404 {
> > +			reg = <0x404 0x10>;
> > +		};
> > +
> > +		tsens_calibration_bckp: calib_bckp@504 {
> > +			reg = <0x504 0x11>;
> > +			bit-offset = 6;
> > +			nbits = 128;
> > +		};
> > +
> > +		pvs_version: pvs-version@6 {
> > +			reg = <0x6 0x2>
> > +			bit-offset = 7;
> > +			nbits = 2;
> > +		};
> > +
> > +		speed_bin: speed-bin@c{
> > +			reg = <0xc 0x1>;
> > +			bit-offset = 2;
> > +			nbits	= 3;
> > +
> > +		};
> > +		...
> > +	};
> > +
> > += Data consumers =
> > +Are device nodes which consume nvmem data cells/providers.
> > +
> > +Required-properties:
> > +nvmem-cell: list of phandle to the nvmem data cells.
> > +nvmem-cell-names: names for the each nvmem-cell specified
> > +
> > +Optional-properties:
> > +nvmem	: list of phandles to nvmem providers.
> > +nvmem-names: names for the each nvmem provider.
>
> Is nvmem-names required if nvmem is used?
Yes, will fix it.
>
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