[PATCH v2 1/4] pinctrl: add samsung pinctrl and gpiolib driver

On 08/21/2012 05:25 AM, Linus Walleij wrote:

On Wed, Aug 15, 2012 at 9:57 PM, Thomas Abraham
[off-list ref] wrote:

quoted

Add a new device tree enabled pinctrl and gpiolib driver for Samsung
SoC's.

...

quoted

+  The child node can also optionally specify one or more of the pin
+  configuration that should be applied on all the pins listed in the
+  "samsung,pins" property of the child node. The following pin configuration
+  properties are supported.
+
+  - samsung,pin-pud: Pull up/down configuration.
+  - samsung,pin-drv: Drive strength configuration.
+  - samsung,pin-pud-pdn: Pull up/down configuration in power down mode.
+  - samsung,pin-drv-pdn: Drive strength configuration in power down mode.

This looks a bit scary, as it seems to be orthogonal to the pin config
interface. I.e. this will be programmed "behind the back" of the
pin config system. However as long as the pin config implementation
reads back these things from the registers it will work, too.

In the U300 and Ux500 I explicitly use pin config hogs to set up
the pin configuration, and when we enter a state such as
"default" the mux setting and config settings are set from the
framework separately.

I know that some HW has a separate set of registers (or fields) for the
"awake" and "sleep" configuration, and the HW switches between the two
automatically when sleeping. I have no idea if the Samsung SoCs do this,
but I think if this were the case, it'd be quite legitimate to define
both these HW states as separate sets of properties within a single
pinctrl SW state. So, that might be the explanation here?