Re: [PATCH v8 3/6] software node: implement reference properties

Lukasz Stelmach
2020-11-09T17:03:02Z

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It was <2019-11-07 czw 20:22>, when Dmitry Torokhov wrote:
> It is possible to store references to software nodes in the same fashion as
> other static properties, so that users do not need to define separate
> structures:
>
> static const struct software_node gpio_bank_b_node = {
> .name = "B",
> };
>
> static const struct property_entry simone_key_enter_props[] = {
> PROPERTY_ENTRY_U32("linux,code", KEY_ENTER),
> PROPERTY_ENTRY_STRING("label", "enter"),
> PROPERTY_ENTRY_REF("gpios", &gpio_bank_b_node, 123, GPIO_ACTIVE_LOW),
> { }
> };
>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---

I am writing a piece that needs to provide a list of gpios to a
diriver. The above example looks like what I need.

At the moment the driver gets the list from fwnode/of_node. The list
contain references to phandles which get resolved and and the driver
ends up with a bunch of gpio descriptors. Great.

This example looks nice but does the code that reads the reference from
the gpios property and returns a gpiod actually exist? If it doesn't, I
am willing to write it.

At first glance it makes more sense to me to pass (struct gpiod_lookup
*) instead of (struct software_node *) and make gpiolib's gpiod_find()
accept lookup tables as parameter instead of searching the
gpio_lookup_list? Or do you think such temporary table should be
assembled from the above structure and then used in gpiod_find()?

Any other suggestions on how to get a bunch of gpios (the description
for gpios is available in the devicetree) for a device described with a
software nodes?

Kind regards,
--
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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