On Wed, May 31, 2017 at 9:58 AM, Baolin Wang [off-list ref] wrote:

On 一,  5月 29, 2017 at 06:18:29下午 +0200, Linus Walleij wrote:

quoted

quoted

+pad driving level, system control select

Actually I do not understand at all what "domain pad driving level"
or "system control select" means, those are very generic terms.
Can you describe precisely what it means? What domain? What
is a domain pad? What kind of system control? What is it selecting
between?

I try to explain what they are on Spreadtrum platform. One pin can output
3.0v or 1.8v, depending on the related domain pad driving selection, if
the related domain pad slect 3.0v, then the pin can output 3.0v.

This can probably use the generic pin control property
PIN_CONFIG_POWER_SOURCE (see include/linux/pinctrl/pinconf-generic.h)
and the corresponding DT binding "power-source" see
drivers/pinctrl/pinconf-generic.c and
Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt

"system control" is used to choose this function (like: UART0) for which
system, since we have several systems (AP/CP/CM4) on one SoC.

Aha, that sounds like a very spreadtrum-specific feature actually.

Since we have lots of different pin configuration to set, it will be hard to
use the standard pin config describing in binding files. But I will try to
remove the magic number and use the common pin config.

It is possible to use generic config and add a few custom bindings
"on top" of it. See for example:
Documentation/devicetree/bindings/pinctrl/qcom,pmic-mpp.txt
mixing a few generic and Qualcomm-specific pin config things,
and their driver is here:
drivers/pinctrl/qcom/pinctrl-spmi-mpp.c

Yours,
Linus Walleij
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