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Date: Wed, 18 Mar 2020 13:28:05 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/13] coresight: cti: Add sysfs coresight mgmt register access
On Wed, 18 Mar 2020 at 12:22, Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Wed, Mar 18, 2020 at 12:16:04PM -0600, Mathieu Poirier wrote:
> > On Wed, Mar 18, 2020 at 02:18:21PM +0100, Greg KH wrote:
> > > On Mon, Mar 09, 2020 at 10:17:37AM -0600, Mathieu Poirier wrote:
> > > > From: Mike Leach <mike.leach@...aro.org>
> > > >
> > > > Adds sysfs access to the coresight management registers.
> > > >
> > > > Signed-off-by: Mike Leach <mike.leach@...aro.org>
> > > > Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> > > > Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
> > > > [Fixed abbreviation in title]
> > > > Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> > > > ---
> > > > .../hwtracing/coresight/coresight-cti-sysfs.c | 53 +++++++++++++++++++
> > > > drivers/hwtracing/coresight/coresight-priv.h | 1 +
> > > > 2 files changed, 54 insertions(+)
> > > >
> > > > diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> > > > index a832b8c6b866..507f8eb487fe 100644
> > > > --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> > > > +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> > > > @@ -62,11 +62,64 @@ static struct attribute *coresight_cti_attrs[] = {
> > > > NULL,
> > > > };
> > > >
> > > > +/* register based attributes */
> > > > +
> > > > +/* macro to access RO registers with power check only (no enable check). */
> > > > +#define coresight_cti_reg(name, offset) \
> > > > +static ssize_t name##_show(struct device *dev, \
> > > > + struct device_attribute *attr, char *buf) \
> > > > +{ \
> > > > + struct cti_drvdata *drvdata = dev_get_drvdata(dev->parent); \
> > > > + u32 val = 0; \
> > > > + pm_runtime_get_sync(dev->parent); \
> > > > + spin_lock(&drvdata->spinlock); \
> > > > + if (drvdata->config.hw_powered) \
> > > > + val = readl_relaxed(drvdata->base + offset); \
> > > > + spin_unlock(&drvdata->spinlock); \
> > > > + pm_runtime_put_sync(dev->parent); \
> > > > + return scnprintf(buf, PAGE_SIZE, "0x%x\n", val); \
> > > > +} \
> > > > +static DEVICE_ATTR_RO(name)
> > > > +
> > > > +/* coresight management registers */
> > > > +coresight_cti_reg(devaff0, CTIDEVAFF0);
> > > > +coresight_cti_reg(devaff1, CTIDEVAFF1);
> > > > +coresight_cti_reg(authstatus, CORESIGHT_AUTHSTATUS);
> > > > +coresight_cti_reg(devarch, CORESIGHT_DEVARCH);
> > > > +coresight_cti_reg(devid, CORESIGHT_DEVID);
> > > > +coresight_cti_reg(devtype, CORESIGHT_DEVTYPE);
> > > > +coresight_cti_reg(pidr0, CORESIGHT_PERIPHIDR0);
> > > > +coresight_cti_reg(pidr1, CORESIGHT_PERIPHIDR1);
> > > > +coresight_cti_reg(pidr2, CORESIGHT_PERIPHIDR2);
> > > > +coresight_cti_reg(pidr3, CORESIGHT_PERIPHIDR3);
> > > > +coresight_cti_reg(pidr4, CORESIGHT_PERIPHIDR4);
> > > > +
> > > > +static struct attribute *coresight_cti_mgmt_attrs[] = {
> > > > + &dev_attr_devaff0.attr,
> > > > + &dev_attr_devaff1.attr,
> > > > + &dev_attr_authstatus.attr,
> > > > + &dev_attr_devarch.attr,
> > > > + &dev_attr_devid.attr,
> > > > + &dev_attr_devtype.attr,
> > > > + &dev_attr_pidr0.attr,
> > > > + &dev_attr_pidr1.attr,
> > > > + &dev_attr_pidr2.attr,
> > > > + &dev_attr_pidr3.attr,
> > > > + &dev_attr_pidr4.attr,
> > > > + NULL,
> > > > +};
> > > > +
> > > > static const struct attribute_group coresight_cti_group = {
> > > > .attrs = coresight_cti_attrs,
> > > > };
> > > >
> > > > +static const struct attribute_group coresight_cti_mgmt_group = {
> > > > + .attrs = coresight_cti_mgmt_attrs,
> > > > + .name = "mgmt",
> > > > +};
> > > > +
> > > > const struct attribute_group *coresight_cti_groups[] = {
> > > > &coresight_cti_group,
> > > > + &coresight_cti_mgmt_group,
> > > > NULL,
> > > > };
> > > > diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> > > > index 82e563cdc879..aba6b789c969 100644
> > > > --- a/drivers/hwtracing/coresight/coresight-priv.h
> > > > +++ b/drivers/hwtracing/coresight/coresight-priv.h
> > > > @@ -22,6 +22,7 @@
> > > > #define CORESIGHT_CLAIMCLR 0xfa4
> > > > #define CORESIGHT_LAR 0xfb0
> > > > #define CORESIGHT_LSR 0xfb4
> > > > +#define CORESIGHT_DEVARCH 0xfbc
> > > > #define CORESIGHT_AUTHSTATUS 0xfb8
> > > > #define CORESIGHT_DEVID 0xfc8
> > > > #define CORESIGHT_DEVTYPE 0xfcc
> > > > --
> > > > 2.20.1
> > > >
> > >
> > > I do not see any Documentation/ABI/ entries for these new sysfs files,
> > > did I miss it somehow? I can't take new sysfs code without
> > > documentation.
> >
> > All the ABI is documented in this patch, which is part of this set.
> >
> > [1]. https://lkml.org/lkml/2020/3/9/642
>
> That is not in the required Documentation/ABI/ form that all sysfs files
> should have. If they don't, it's a bug.
Now I'm very confused... As far as I can tell Mike has followed the
(very loose) guidelines set out in the ABI documentation [1]. I have
also taken a look at the patches that were merged in the v5.5 cycle -
nothing is very different than what Mike has put together. It is also
based on the work I did a while back [2] that you merged.
The only thing I can see is that under "Contact", names are listed
rather than name and email addresses - is this what you are referring
to? Is there another problem? Can you point me to a file where the
"right" format has been followed?
Thanks,
Mathieu
[1]. https://elixir.bootlin.com/linux/v5.6-rc6/source/Documentation/ABI/README
[2]. https://elixir.bootlin.com/linux/v5.6-rc6/source/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x
>
> Please use that format and do not make up your own, we already have
> tools that parse these files.
>
> thanks,
>
> greg k-h
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