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

From: Scott Wood <[email-masked]>
Date: Wed, 3 Oct 2012 17:20:07 -0500

On 10/03/2012 08:35:58 AM, Kumar Gala wrote:
>=20
> On Oct 3, 2012, at 5:42 AM, Wang Dongsheng wrote:
>=20
> > This is only for freescale powerpc platform. The driver provides a =20
> way
> > to wake up system. Proc =20
> interface(/proc/powerpc/wakeup_timer_seconds).
> >
> > eg: "echo 5 > /proc/powerpc/wakeup_timer_seconds", 5 seconds
> > after the system will be woken up. echo another time into proc =20
> 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 =20
> +++++++++++++++++++++++++++++
> > 3 files changed, 241 insertions(+)
> > create mode 100644 arch/powerpc/platforms/fsl_timer_wakeup.c
>=20
> Adding the Linux PM list to see if there is some existing support for =20
> this on other arch's in kernel.
>=20
> I'm pretty sure /proc/ is NOT where we want this exposed.

Should probably go under the sysfs directory of the mpic device.  Or =20
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.

> > diff --git a/arch/powerpc/platforms/Kconfig =20
> 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 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 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 another
> > +	  time into proc interface to update the time.
> > +
> > +endif

Use depends rather than if/else.  Why do you need FSL_WAKEUP_SOURCE?

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).

> > +static ssize_t timer_wakeup_write(struct file *file, const char =20
> __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, priv, =20
> &time);

If the new time is zero, consider that a cancellation of the timer and =20
don't request a new one or return -EINVAL.

-Scott=