Subject: Re: [RFC PATCH] powerpc/fsl: add timer wakeup source

From: Scott Wood <[email-masked]>
Date: Mon, 8 Oct 2012 15:55:05 -0500

On 10/08/2012 02:13:26 AM, Wang Dongsheng-B40534 wrote:
>=20
>=20
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Thursday, October 04, 2012 6:20 AM
> > To: Kumar Gala
> > Cc: Wang Dongsheng; Wood Scott-B07421; =20
> [email-masked] list;
> > Wang Dongsheng-B40534; Li Yang-R58472; [email-masked]
> > Subject: Re: [RFC PATCH] powerpc/fsl: add timer wakeup source
> >
> > On 10/03/2012 08:35:58 AM, Kumar Gala wrote:
> > >
> > > On Oct 3, 2012, at 5:42 AM, Wang Dongsheng wrote:
> > >
> > > > This is only for freescale powerpc platform. The driver =20
> provides a
> > > way
> > > > to wake up system. Proc
> > > interface(/proc/powerpc/wakeup_timer_seconds).
> > > >
> > > > eg: "echo 5 > /proc/powerpc/wakeup_timer_seconds", 5 seconds =20
> after
> > > > the system will be woken up. echo another time into proc
> > > interface
> > > > to update the time.
> > > >
> > > > Signed-off-by: Wang Dongsheng <[email-masked]>
> > > > Signed-off-by: Li Yang <[email-masked]>
> > > > ---
> > > > arch/powerpc/platforms/Kconfig            |   23 +++
> > > > arch/powerpc/platforms/Makefile           |    1 +
> > > > arch/powerpc/platforms/fsl_timer_wakeup.c |  217
> > > +++++++++++++++++++++++++++++
> > > > 3 files changed, 241 insertions(+)
> > > > create mode 100644 arch/powerpc/platforms/fsl_timer_wakeup.c
> > >
> > > Adding the Linux PM list to see if there is some existing support =20
> for
> > > this on other arch's in kernel.
> > >
> > > I'm pretty sure /proc/ is NOT where we want this exposed.
> >
> > Should probably go under the sysfs directory of the mpic device.  Or
> > better, make a generic interface for timer-based suspend wakeup (if =20
> there
> > isn't one already).  This current approach sits in an unpleasant =20
> middle
> > ground between generic and device-specific.
> > =09
> /sys/power/wakeup_timer_seconds how about this?
> I think it is a freescale generic interface, this interface control by
> FSL_SOC && SUSPEND.

There's no such thing as a "Freescale generic interface".  Linux APIs =20
are not organized by hardware vendor.  Either make a truly generic =20
interface, reuse an existing one, or do something that is attached to =20
the specific driver.

> > > > diff --git a/arch/powerpc/platforms/Kconfig
> > > b/arch/powerpc/platforms/Kconfig
> > > > index b190a6e..7b9232a 100644
> > > > --- a/arch/powerpc/platforms/Kconfig
> > > > +++ b/arch/powerpc/platforms/Kconfig
> > > > @@ -99,6 +99,29 @@ config MPIC_TIMER
> > > > 	  only tested on fsl chip, but it can potentially =20
> support
> > > > 	  other global timers complying to Open-PIC standard.
> > > >
> > > > +menuconfig FSL_WAKEUP_SOURCE
> > > > +	bool "Freescale wakeup source"
> > > > +	depends on FSL_SOC && SUSPEND
> > > > +	default n
> > > > +	help
> > > > +	  This option enables wakeup source for wake up system
> > > > +	  features. This is only for freescale powerpc platform.
> > > > +
> > > > +if FSL_WAKEUP_SOURCE
> > > > +
> > > > +config FSL_TIMER_WAKEUP
> > > > +	tristate "Freescale mpic global timer wakeup event"
> > > > +	default n
> > > > +	help
> > > > +	  This is only for freescale powerpc platform. The =20
> driver
> > > > +	  provides a way to wake up system.
> > > > +	  Proc interface(/proc/powerpc/wakeup_timer_seconds).
> > > > +	  eg: "echo 5 > /proc/powerpc/wakeup_timer_seconds",
> > > > +	  5 seconds after the system will be woken up. echo =20
> another
> > > > +	  time into proc interface to update the time.
> > > > +
> > > > +endif
> >
> > Use depends rather than if/else.  Why do you need FSL_WAKEUP_SOURCE?
> >
> It lists all wake up source. If later have wakeup source can be =20
> improved by
> it to control. Buttons event wakeup source will be added after the =20
> timer.

It does not list all wake up sources -- there's also ethernet, USB, etc.

> > These names are overly broad -- this is only for FSL MPIC, not for =20
> other
> > FSL chips (e.g. mpc83xx has a different global timer =20
> implementation, and
> > there's FSL ARM chips, etc).
> >
> Yes, thanks. Change to FSL_MPIC_TIMER_WAKEUP.
>=20
> > > > +static ssize_t timer_wakeup_write(struct file *file, const char
> > > __user *buf,
> > > > +		size_t count, loff_t *off)
> > > > +{
> > > > +	struct fsl_timer_wakeup *priv;
> > > > +	struct inode *inode =3D file->f_path.dentry->d_inode;
> > > > +	struct proc_dir_entry *dp;
> > > > +	struct timeval time;
> > > > +	char *kbuf;
> > > > +
> > > > +	dp =3D PDE(inode);
> > > > +	priv =3D dp->data;
> > > > +
> > > > +	kbuf =3D kzalloc(count + 1, GFP_KERNEL);
> > > > +	if (!kbuf)
> > > > +		return -ENOMEM;
> > > > +
> > > > +	if (copy_from_user(kbuf, buf, count)) {
> > > > +		kfree(kbuf);
> > > > +		return -EFAULT;
> > > > +	}
> > > > +
> > > > +	kbuf[count] =3D '\0';
> > > > +
> > > > +	if (kstrtol(kbuf, 0, &time.tv_sec)) {
> > > > +		kfree(kbuf);
> > > > +		return -EINVAL;
> > > > +	}
> > > > +
> > > > +	kfree(kbuf);
> > > > +
> > > > +	time.tv_usec =3D 0;
> > > > +
> > > > +	mutex_lock(&priv->mutex);
> > > > +
> > > > +	if (!time.tv_sec) {
> > > > +		if (priv->timer) {
> > > > +			mpic_free_timer(priv->timer);
> > > > +			priv->timer =3D NULL;
> > > > +		}
> > > > +		mutex_unlock(&priv->mutex);
> > > > +
> > > > +		return count;
> > > > +	}
> > > > +
> > > > +	if (priv->timer) {
> > > > +		mpic_free_timer(priv->timer);
> > > > +		priv->timer =3D NULL;
> > > > +	}
> > > > +
> > > > +	priv->timer =3D mpic_request_timer(timer_event_interrupt, =20
> priv,
> > > &time);
> >
> > If the new time is zero, consider that a cancellation of the timer =20
> and
> > don't request a new one or return -EINVAL.
> >
> Thanks, I think i should add comments. Let this patch easy to read.
> Here is get a new timer.
> If the new time is zero, consider that has been checked.
>=20
> if (!time.tv_sec) {...} this is check zero.
> The "mpic_request_timer" before this code.

Ah, I see.  Wouldn't it be simpler to remove that block and just test =20
time.tv_sec when requesting the new timer?

-Scott=