On Mon, 24 Nov 2008, Deepak Saxena wrote:
>
>
> Hi,
>
> On the OLPC XO laptop, we want a way to enable/disable wakeup events for
> a device from userspace at suspend time depending on the method we are
> using for suspending. For example, if the system auto-suspends, we want
> to wake up on input from the PS2 device; if the user shuts the lid, we
> want to wakeup on lid state change events; if the user presses the power
> button to suspend, we only want to wakeup on another power button event.
>
> We have currently exported a set of files via sysfs in
> /sys/power/wakeup_events as such:
>
> bash-3.2# ls /sys/power/wakeup_events/
> ac_power battery_error battery_state ps2event
> all battery_soc ebook_mode_change wlan
>
> Writing a 1 to one of these files will enable that device as a wake up
> source in the Embedded Controller (EC). Writing a 0 will disable it. See
> [1] for code. This interface works but I would like to replace it with
> something that can be pushed upstream.
>
> Each of the devices we care about already has an entry in the sysfs tree
> or could have one added and each of these entries has a "power/wakeup" file
> that according to my reading of the code, can be set to "enabled" or "disabled".
> What we need is a way to tie the enable/disable state to some sort of platform
> handler so that we do not end up with platform-specific code in each
> driver. What I propose is adding a generic structure that a platform
> can register:
>
> struct platform_wakeup_ops {
> init_wakeup(struct device *dev, int val);
> set_wakeup_capable(struct device *dev, int val);
> can_wakeup(struct device *dev);
> set_wakeup_eanble(struct device *dev, int val);
> may_wakeup(struct device *dev);
> };
>
> wakeup_register_ops(struct platform_wakeup_ops *ops);
>
> The generic functions in pm_wakeup.h can be modified to call the platform
> level code if such is registered. The platform level code can do whatever
> it wants w/o needing to touch generic code. In our case, we can look at
> dev->bus->name && dev->busid to determine if we need to change an EC bit.
> If not, we just do the default behaviour as per pm_wakeup.h. We can
> add __device_init_wakeup() and other "__" functions that can be called
> by platform code that do the default action.
>
> Thoughts?
Shouldn't these things be decided by the user and not by the kernel's
platform code?
So what you want is a way for userspace to know and react at the start
of a suspend, and a way for it to know the cause of the suspend. Then
a daemon could be set to notice whenever a suspend is started, and it
could set all the various wakeup flags however the user wants.
Alan Stern
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