On Thu, Jun 14, 2018 at 4:33 PM, Rob Herring [off-list ref] wrote:

On Thu, Jun 14, 2018 at 8:14 AM, Linus Walleij [off-list ref] wrote:

quoted

On Wed, Jun 13, 2018 at 9:28 PM, Rob Herring [off-list ref] wrote:

quoted

quoted

"Some system-on-chips (SoCs) use the concept of GPIO banks. ...
Usually each such bank is
exposed in the device tree as an individual gpio-controller node. ..."

This should be conditioned on being able to divide up the registers by
bank which seems like you can't. Or there's the case like the DW GPIO
block and the number of banks is configurable.

If it is possible to create one device per bank I usually prefer that
approach, as it also (often) makes it possible to use the
generic GPIO library, i.e. the hardware abstraction start to
share more with other GPIO controllers.

But that should be possible whether there are banks in DT or not, right?

Possible yes, but more complex, requireing a bigger and more complex
chunk of code to get it right. Which we don't have for Linux (I don't know
about $OS).

For 1 bank = 1 device, all callbacks etc naturally offsets to something
like 0..31 landing in (1 << offset) which makes for a simple support library.

If there is more complex calculations, more complex helper libs are
required and maybe not even worth it, ending up with more duplicated
or slightly-different code.

Yours,
Linus Walleij