linux-kernel - Re: [PATCH] omap3: make coresight register save across OFF modes a sysfs option

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Date:	Mon, 26 Jul 2010 10:32:16 +0300
From:	Alexander Shishkin <virtuoso@...nd.org>
To:	"Shilimkar, Santosh" <santosh.shilimkar@...com>
Cc:	Hari Kanigeri <hari.kanigeri@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	Paul Walmsley <paul@...an.com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] omap3: make coresight register save across OFF modes a
 sysfs option

On Mon, Jul 26, 2010 at 12:28:38 +0530, Shilimkar, Santosh wrote:
> > -----Original Message-----
> > From: linux-omap-owner@...r.kernel.org [mailto:linux-omap-
> > owner@...r.kernel.org] On Behalf Of Alexander Shishkin
> > Sent: Monday, July 26, 2010 2:34 AM
> > To: Hari Kanigeri
> > Cc: Alexander Shishkin; linux-arm-kernel@...ts.infradead.org; Tony
> > Lindgren; Russell King; Paul Walmsley; Kevin Hilman; linux-
> > omap@...r.kernel.org; linux-kernel@...r.kernel.org
> > Subject: [PATCH] omap3: make coresight register save across OFF modes a
> > sysfs option
> > 
> > This adds a sysfs file at /sys/power/coresight_save which is used to
> > control if the ETM and debug components' states should be saved and
> > restored across OFF modes.
> > 
> > Signed-off-by: Alexander Shishkin <virtuoso@...nd.org>
> > Cc: Tony Lindgren <tony@...mide.com>
> > Cc: Russell King <linux@....linux.org.uk>
> > Cc: Paul Walmsley <paul@...an.com>
> > Cc: Kevin Hilman <khilman@...prootsystems.com>
> > Cc: linux-omap@...r.kernel.org
> > Cc: linux-arm-kernel@...ts.infradead.org
> > Cc: linux-kernel@...r.kernel.org
> > ---
> >  arch/arm/mach-omap2/Makefile    |    1 +
> >  arch/arm/mach-omap2/debug34xx.c |   66
> > +++++++++++++++++++++++++++++++++++++++
> >  arch/arm/mach-omap2/pm.h        |    6 +++
> >  arch/arm/mach-omap2/pm34xx.c    |    3 ++
> >  4 files changed, 76 insertions(+), 0 deletions(-)
> >  create mode 100644 arch/arm/mach-omap2/debug34xx.c
> > 
> > diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
> > index f5b4ff4..3a64ce4 100644
> > --- a/arch/arm/mach-omap2/Makefile
> > +++ b/arch/arm/mach-omap2/Makefile
> > @@ -49,6 +49,7 @@ ifeq ($(CONFIG_PM),y)
> >  obj-$(CONFIG_ARCH_OMAP2)		+= pm24xx.o
> >  obj-$(CONFIG_ARCH_OMAP2)		+= sleep24xx.o
> >  obj-$(CONFIG_ARCH_OMAP3)		+= pm34xx.o sleep34xx.o cpuidle34xx.o
> > +obj-$(CONFIG_ENABLE_OFF_MODE_JTAG_ETM_DEBUG) += debug34xx.o
> >  obj-$(CONFIG_PM_DEBUG)			+= pm-debug.o
> > 
> >  AFLAGS_sleep24xx.o			:=-Wa,-march=armv6
> > diff --git a/arch/arm/mach-omap2/debug34xx.c b/arch/arm/mach-
> > omap2/debug34xx.c
> > new file mode 100644
> > index 0000000..698e83a
> > --- /dev/null
> > +++ b/arch/arm/mach-omap2/debug34xx.c
> 
> > @@ -0,0 +1,66 @@
> > +/*
> > + * Control saving and restoring of coresight components' state during
> > + * OFF mode.
> > + *
> > + * Copyright (C) 2010 Nokia Corporation
> > + * Alexander Shishkin
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/sysfs.h>
> > +#include <linux/kobject.h>
> > +
> > +#include "pm.h"
> > +
> > +/*
> > + * Pointer to a place in sram where the ETM/debug state save
> > + * flag is. It can be calculated after the omap_sram_idle is
> > + * pushed to sram.
> > + */
> > +static unsigned int *_etm_save;
> > +
> > +/*
> > + * sysfs file /sys/power/coresight_save controls whether the
> > + * state of coresight components should be saved and restored
> > + * across OFF modes.
> > + */
> > +static ssize_t coresight_save_show(struct kobject *kobj,
> > +				  struct kobj_attribute *attr,
> > +				  char *buf)
> > +{
> > +	return sprintf(buf, "%u\n", *_etm_save);
> > +}
> > +
> > +static ssize_t coresight_save_store(struct kobject *kobj,
> > +				   struct kobj_attribute *attr,
> > +				   const char *buf, size_t n)
> > +{
> > +	unsigned int value;
> > +
> > +	if (sscanf(buf, "%u", &value) != 1)
> > +		return -EINVAL;
> > +
> > +	*_etm_save = !!value;
> > +
> > +	return n;
> > +}
> > +
> > +static struct kobj_attribute coresight_save_attr =
> > +	__ATTR(coresight_save, 0644, coresight_save_show,
> > coresight_save_store);
> > +
> > +int omap3_coresight_pm_init(void *sram_addr)
> > +{
> > +	int ret;
> > +
> > +	/* the last word from the top of omap_sram_idle */
> > +	_etm_save = (unsigned *)((u8 *)sram_addr + omap34xx_cpu_suspend_sz -
> > 4);
> > +
> > +	ret = sysfs_create_file(power_kobj, &coresight_save_attr.attr);
> > +
> > +	return ret;
> > +}
> 
> Looking at content of this file, I think you can keep this under common 
> pm-debug.c file. 
> Any problems with that ?

I was trying to avoid #ifdeffing too much and I didn't want this code to
compile at all when CONFIG_ENABLE_OFF_MODE_JTAG_ETM_DEBUG is not set.
Otherwise, no problems.

Regards,
--
Alex
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