On 08.08.2014 14:36, Linus Walleij wrote:
On Thu, Jul 24, 2014 at 5:51 PM, Tomasz Nowicki
<tomasz.nowicki@xxxxxxxxxx> wrote:
GPIO signaled events is quite new thing in Linux kernel.
AFAIK, there are not many board which can take advantage of it.
However, GPIO events are very useful feature during work on ACPI
subsystems.
Overall this seems like a pretty nice debug feature.
This commit emulates GPIO h/w behaviour and consists on read/write
operation to debugfs file. GPIO device instance is still required in DSDT
table along with _AEI resources and event methods.
Reading from file provides pin to GPIO device map e.g. :
$ cat /sys/kernel/debug/acpi/gpio_event
GPIO device name: /__SB.GPI0
Available GPIO pin map:
/__SB.GPI0 <-> pin 0x100
Based on that, user can trigger method corresponding to device pin number:
$ echo "/__SB.GPI0 0x100" > /sys/kernel/debug/acpi/gpio_event
I need input from Rafael and Mika as to whether this is a
good interface.
It seems a bit confusing for me: why do you have to extract
a number from one file and then insert the same magic number
somewhere else?
Good point! Available GPIO event pins should be listed as debugfs node,
then user would write e.g. 1 to one particular. Sounds simpler.
Regards,
Tomasz Nowicki
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