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SubjectRe: [PATCH 11/13] nvmem: add support for cell lookups from machine code
2018-09-05 16:21 GMT+02:00 Boris Brezillon <boris.brezillon@bootlin.com>:
> On Wed, 5 Sep 2018 16:00:36 +0200
> Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
>> 2018-09-05 15:57 GMT+02:00 Boris Brezillon <boris.brezillon@bootlin.com>:
>> > On Wed, 5 Sep 2018 11:57:36 +0200
>> > Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>> >
>> >>
>> >> +struct nvmem_cell_lookup {
>> >> + const char *nvmem_name;
>> >> + const char *dev_id;
>> >
>> > Shouldn't we have a con_id here?
>> >
>> >> + const char *cell_id;
>> >> + struct list_head node;
>> >> +};
>>
>> I wanted to stay in line with the current API - nvmem_cell_get() takes
>> as argument a string called cell_id. I wanted to reflect that here.
>
> Actually, you need both. con_id is the name you would have in your DT
> in the nvmem-cell-names property, cell_id is the name of the cell
> you'd find under the nvmem device node.
>
> Let's take an example:
>
> mydev {
> #nvmem-cell-names = "mac-address", "revision";
> #nvmem-cells = <&cell1>, <&cell2>;
> };
>
> mynvmemdev {
> #size-cells = <1>;
> #address-cells = <1>;
>
> cell1: foo@0 {
> reg = <0x0 0x6>;
> };
>
> cell2: bar@6 {
> reg = <0x6 0x10>;
> };
> };
>
> this can be described the same way using a consumer lookup table:
>
> struct nvmem_cell_lookup_entry {
> const char *con_id;
> const char *nvmem_name;
> const char *cell_name;
> };
>
> struct nvmem_cell_lookup_table {
> struct list_head node;
> const char *dev_id;
> unsigned int nentries;
> const struct nvmem_cell_lookup_entry *entries;
> }
>
> static const struct nvmem_cell_lookup_entry mydev_nvmem_cells[] = {
> {
> .con_id = "mac-address",
> .nvmem_name = "mynvmemdev",
> .cell_name = "foo",
> },
> {
> .con_id = "revision",
> .nvmem_name = "mynvmemdev",
> .cell_name = "bar",
> },
> }
>
> static const struct nvmem_cell_lookup_table mydev_nvmem_lookup = {
> .dev_id = "mydev.0",
> .nentries = ARRAY_SIZE(mydev_nvmem_cells),
> .entries = mydev_nvmem_cells,
> };
>
>
> ...
>
> nvmem_add_cell_lookups(&mydev_nvmem_lookup);

Ok I get it. Shouldn't we change the argument name of nvmem_cell_get()
and friends from 'name' to 'con_id' or simply 'id' similarly to what
other frameworks do to avoid such confusion?

I also don't see a need for splitting the lookup into two structures
here. Something like:

struct nvmem_cell_lookup {
const char *nvmem_name;
const char *cell_name;
const char *dev_id;
const char *con_id;
};

Would be perfectly fine and would allow to register all lookups for
given machine with a single call. How often does it happen that a
single device needs multiple nvmem cells anyway?

Bart

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