gpiobus_hinted_child >32 pins support, pin_getname method, and gpio-sysctl bridge patch

[Warner Losh]

On Aug 19, 2012, at 5:04 PM, Tim Kientzle wrote:

> On Aug 19, 2012, at 10:02 AM, Warner Losh wrote:
>> 
>> On Aug 19, 2012, at 10:03 AM, Tim Kientzle wrote:
>> 
>>> On Aug 19, 2012, at 8:38 AM, Warner Losh wrote:
>>> 
>>>> 
>>>> In general, I like this code in the context of the current GPIO framework.  I've been growing dissatisfied with the current GPIO framework, however, and some of my comments reflect that more than any comments about this specific code.
>>> 
>>> I noticed that Linux on BeagleBone does not
>>> simply number all pins as we do.  Pins are identified by
>>> two numbers:  a unit number and a pin number.
>> 
>> Is this in the code, or just in the FTD?  On Atmel, there's a single number from 0 to max-1 with all negative numbers being invalid.  But Atmel doesn't have proper FTD support in Linux just yet (3.5 has a good start, and 3.6 will add the missing pinmux/pinctl stuff).
> 
> I'm not exactly sure what you mean.  The Linux DTS file:
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=arch/arm/boot/dts/am335x-bone.dts
> 
> inherits most of the real functionality from
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=arch/arm/boot/dts/am33xx.dtsi
> 
> There are certainly separate entries there for each GPIO module.  I presume (but haven't verified) that the unit number maps directly to a "gpio#" device name.

There's similar things in the Atmel DTS files, but under the covers the gpio pins map into a uniform space number 0 to 32*N-1, where N is the number of GPIO units.

Warner