Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 10 Nov 2020 10:02:33 -0700
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Suzuki K Poulose <suzuki.poulose@arm.com>
Cc:     linux-arm-kernel@lists.infradead.org, mike.leach@linaro.org,
        coresight@lists.linaro.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 07/26] coresight: Introduce device access abstraction
Message-ID: <20201110170233.GA3429138@xps15>
References: <20201028220945.3826358-1-suzuki.poulose@arm.com>
 <20201028220945.3826358-9-suzuki.poulose@arm.com>
 <20201109210042.GF3396611@xps15>
 <cf31b2ef-ab1e-303c-e995-dc9b7304843a@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <cf31b2ef-ab1e-303c-e995-dc9b7304843a@arm.com>
Precedence: bulk

On Tue, Nov 10, 2020 at 09:24:19AM +0000, Suzuki K Poulose wrote:
> On 11/9/20 9:00 PM, Mathieu Poirier wrote:
> > On Wed, Oct 28, 2020 at 10:09:26PM +0000, Suzuki K Poulose wrote:
> > > We are about to introduce support for sysreg access to ETMv4.4+
> > > component. Since there are generic routines that access the
> > > registers (e.g, CS_LOCK/UNLOCK , claim/disclaim operations, timeout)
> > > and in order to preserve the logic of these operations at a
> > > single place we introduce an abstraction layer for the accesses
> > > to a given device.
> > > 
> > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> > > Cc: Mike Leach <mike.leach@linaro.org>
> > > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> > > ---
> > >   drivers/hwtracing/coresight/coresight-catu.c  |   1 +
> > >   drivers/hwtracing/coresight/coresight-core.c  |  49 +++++
> > >   .../hwtracing/coresight/coresight-cti-core.c  |   1 +
> > >   drivers/hwtracing/coresight/coresight-etb10.c |   1 +
> > >   .../coresight/coresight-etm3x-core.c          |   1 +
> > >   .../coresight/coresight-etm4x-core.c          |   1 +
> > >   .../hwtracing/coresight/coresight-funnel.c    |   1 +
> > >   .../coresight/coresight-replicator.c          |   1 +
> > >   drivers/hwtracing/coresight/coresight-stm.c   |   1 +
> > >   .../hwtracing/coresight/coresight-tmc-core.c  |   1 +
> > >   drivers/hwtracing/coresight/coresight-tpiu.c  |   1 +
> > >   include/linux/coresight.h                     | 197 ++++++++++++++++++
> > >   12 files changed, 256 insertions(+)
> > > 
> > > diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c
> > > index 99430f6cf5a5..5baf29510f1b 100644
> > > --- a/drivers/hwtracing/coresight/coresight-catu.c
> > > +++ b/drivers/hwtracing/coresight/coresight-catu.c
> > > @@ -551,6 +551,7 @@ static int catu_probe(struct amba_device *adev, const struct amba_id *id)
> > >   	dev->platform_data = pdata;
> > >   	drvdata->base = base;
> > > +	catu_desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	catu_desc.pdata = pdata;
> > >   	catu_desc.dev = dev;
> > >   	catu_desc.groups = catu_groups;
> > > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> > > index cc9e8025c533..e96deaca8cab 100644
> > > --- a/drivers/hwtracing/coresight/coresight-core.c
> > > +++ b/drivers/hwtracing/coresight/coresight-core.c
> > > @@ -1452,6 +1452,54 @@ int coresight_timeout(void __iomem *addr, u32 offset, int position, int value)
> > >   }
> > >   EXPORT_SYMBOL_GPL(coresight_timeout);
> > > +u32 coresight_relaxed_read32(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	return csdev_access_relaxed_read32(&csdev->access, offset);
> > > +}
> > > +
> > > +u32 coresight_read32(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	return csdev_access_read32(&csdev->access, offset);
> > > +}
> > > +
> > > +void coresight_relaxed_write32(struct coresight_device *csdev,
> > > +			       u32 val,
> > > +			       u32 offset)
> > > +{
> > > +
> > > +	csdev_access_relaxed_write32(&csdev->access, val, offset);
> > > +}
> > > +
> > > +
> > > +void coresight_write32(struct coresight_device *csdev, u32 val, u32 offset)
> > > +{
> > > +	csdev_access_write32(&csdev->access, val, offset);
> > > +}
> > > +
> > > +u64 coresight_relaxed_read64(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	return csdev_access_relaxed_read64(&csdev->access, offset);
> > > +}
> > > +
> > > +u64 coresight_read64(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	return csdev_access_read64(&csdev->access, offset);
> > > +}
> > > +
> > > +void coresight_relaxed_write64(struct coresight_device *csdev,
> > > +			       u64 val,
> > > +			       u32 offset)
> > > +{
> > > +
> > > +	csdev_access_relaxed_write64(&csdev->access, val, offset);
> > > +}
> > > +
> > > +
> > > +void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset)
> > > +{
> > > +	csdev_access_write64(&csdev->access, val, offset);
> > > +}
> > > +
> > >   /*
> > >    * coresight_release_platform_data: Release references to the devices connected
> > >    * to the output port of this device.
> > > @@ -1516,6 +1564,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
> > >   	csdev->type = desc->type;
> > >   	csdev->subtype = desc->subtype;
> > >   	csdev->ops = desc->ops;
> > > +	csdev->access = desc->access;
> > >   	csdev->orphan = false;
> > >   	csdev->dev.type = &coresight_dev_type[desc->type];
> > > diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
> > > index d28eae93e55c..3bb0de97d66e 100644
> > > --- a/drivers/hwtracing/coresight/coresight-cti-core.c
> > > +++ b/drivers/hwtracing/coresight/coresight-cti-core.c
> > > @@ -870,6 +870,7 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
> > >   		return PTR_ERR(base);
> > >   	drvdata->base = base;
> > > +	cti_desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	dev_set_drvdata(dev, drvdata);
> > > diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
> > > index 248cc82c838e..b91633c6c9b4 100644
> > > --- a/drivers/hwtracing/coresight/coresight-etb10.c
> > > +++ b/drivers/hwtracing/coresight/coresight-etb10.c
> > > @@ -755,6 +755,7 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id)
> > >   		return PTR_ERR(base);
> > >   	drvdata->base = base;
> > > +	desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	spin_lock_init(&drvdata->spinlock);
> > > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > > index 47f610b1c2b1..36c5b0ae1b43 100644
> > > --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > > +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > > @@ -839,6 +839,7 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
> > >   		return PTR_ERR(base);
> > >   	drvdata->base = base;
> > > +	desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	spin_lock_init(&drvdata->spinlock);
> > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > > index 0310eac9dc16..c5cb93f1b80c 100644
> > > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > > @@ -1512,6 +1512,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> > >   		return PTR_ERR(base);
> > >   	drvdata->base = base;
> > > +	desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	spin_lock_init(&drvdata->spinlock);
> > > diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
> > > index af40814ce560..f77466aea26f 100644
> > > --- a/drivers/hwtracing/coresight/coresight-funnel.c
> > > +++ b/drivers/hwtracing/coresight/coresight-funnel.c
> > > @@ -242,6 +242,7 @@ static int funnel_probe(struct device *dev, struct resource *res)
> > >   		}
> > >   		drvdata->base = base;
> > >   		desc.groups = coresight_funnel_groups;
> > > +		desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	}
> > >   	dev_set_drvdata(dev, drvdata);
> > > diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
> > > index 62afdde0e5ea..fcf25740116c 100644
> > > --- a/drivers/hwtracing/coresight/coresight-replicator.c
> > > +++ b/drivers/hwtracing/coresight/coresight-replicator.c
> > > @@ -254,6 +254,7 @@ static int replicator_probe(struct device *dev, struct resource *res)
> > >   		}
> > >   		drvdata->base = base;
> > >   		desc.groups = replicator_groups;
> > > +		desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	}
> > >   	if (fwnode_property_present(dev_fwnode(dev),
> > > diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> > > index b0ad912651a9..315500b7763f 100644
> > > --- a/drivers/hwtracing/coresight/coresight-stm.c
> > > +++ b/drivers/hwtracing/coresight/coresight-stm.c
> > > @@ -884,6 +884,7 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id)
> > >   	if (IS_ERR(base))
> > >   		return PTR_ERR(base);
> > >   	drvdata->base = base;
> > > +	desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	ret = stm_get_stimulus_area(dev, &ch_res);
> > >   	if (ret)
> > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> > > index 5653e0945c74..8fd640d41e1b 100644
> > > --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> > > +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> > > @@ -456,6 +456,7 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
> > >   	}
> > >   	drvdata->base = base;
> > > +	desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	spin_lock_init(&drvdata->spinlock);
> > > diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c
> > > index 566c57e03596..dfa3b91d0281 100644
> > > --- a/drivers/hwtracing/coresight/coresight-tpiu.c
> > > +++ b/drivers/hwtracing/coresight/coresight-tpiu.c
> > > @@ -149,6 +149,7 @@ static int tpiu_probe(struct amba_device *adev, const struct amba_id *id)
> > >   		return PTR_ERR(base);
> > >   	drvdata->base = base;
> > > +	desc.access = CSDEV_ACCESS_IOMEM(base);
> > >   	/* Disable tpiu to support older devices */
> > >   	tpiu_disable_hw(drvdata);
> > > diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> > > index 7d3c87e5b97c..5a34c2f2debc 100644
> > > --- a/include/linux/coresight.h
> > > +++ b/include/linux/coresight.h
> > > @@ -7,6 +7,7 @@
> > >   #define _LINUX_CORESIGHT_H
> > >   #include <linux/device.h>
> > > +#include <linux/io.h>
> > >   #include <linux/perf_event.h>
> > >   #include <linux/sched.h>
> > > @@ -114,6 +115,38 @@ struct coresight_platform_data {
> > >   	struct coresight_connection *conns;
> > >   };
> > > +/**
> > > + * struct csdev_access - Abstraction of a CoreSight device access.
> > > + *
> > > + * @io_mem	: True if the device has memory mapped I/O
> > > + * @base	: When io_mem == true, base address of the component
> > > + * @read	: Read from the given "offset" of the given instance.
> > > + * @write	: Write "val" to the given "offset".
> > > + */
> > > +struct csdev_access {
> > > +	bool io_mem;
> > > +	union {
> > > +		void __iomem *base;
> > > +		struct {
> > > +			u64 (*read)(struct csdev_access *csa,
> > > +				    u32 offset,
> > > +				    bool relaxed,
> > > +				    bool _64bit);
> > > +			void (*write)(struct csdev_access *csa,
> > > +				      u64 val,
> > > +				      u32 offset,
> > > +				      bool relaxed,
> > > +				      bool _64bit);
> > 
> > What is the strategy behing passing a struct csdev_acces to (*read) and
> > (*write)?  I kept looking for it while reviewing this set but couldn't find
> > anything.
> 
> Right now it is unused. But, when I designed it, it was supposed to also
> clean up the ETM3 accesses, where some of them are iomapped and some are
> CP14 access. So, we could use the csa to get the "base" for iomap access
> and also use the sysreg access. This can be another series. Didn't want
> to bloat up this series which is already a mammoth to review.
> 
> Also, the drivers could use the "csa" to do the following :
>   - Get to a container struct for more information to do appropriate
>     actions.
>   - Extend the csa by adding a private field (this was part of one
>     of the drafts, but later dropped to lack of immediate uses).
> 
> I could add in a comment if that helps.

Adding a comment to confirm *csa isn't used will only speed up the reception of
a patchset that will remove it.  I first thought removing it would be invasive
but upon investigating further it is not the case.  As such I think it is best
to take it out and let another patchset add what is needed.

Thanks,
Mathieu

> 
> Cheers
> Suzki
> 
> 
> > 
> > Thanks
> > Mathieu
> > 
> > > +		};
> > > +	};
> > > +};
> > > +
> > > +#define CSDEV_ACCESS_IOMEM(_addr)		\
> > > +	((struct csdev_access)	{		\
> > > +		.io_mem		= true,		\
> > > +		.base		= (_addr),	\
> > > +	})
> > > +
> > >   /**
> > >    * struct coresight_desc - description of a component required from drivers
> > >    * @type:	as defined by @coresight_dev_type.
> > > @@ -125,6 +158,7 @@ struct coresight_platform_data {
> > >    * @groups:	operations specific to this component. These will end up
> > >    *		in the component's sysfs sub-directory.
> > >    * @name:	name for the coresight device, also shown under sysfs.
> > > + * @access:	Describe access to the device
> > >    */
> > >   struct coresight_desc {
> > >   	enum coresight_dev_type type;
> > > @@ -134,6 +168,7 @@ struct coresight_desc {
> > >   	struct device *dev;
> > >   	const struct attribute_group **groups;
> > >   	const char *name;
> > > +	struct csdev_access access;
> > >   };
> > >   /**
> > > @@ -186,6 +221,7 @@ struct coresight_sysfs_link {
> > >    * @def_sink:	cached reference to default sink found for this device.
> > >    * @ect_dev:	Associated cross trigger device. Not part of the trace data
> > >    *		path or connections.
> > > + * @access:	Device i/o access abstraction for this device.
> > >    * @nr_links:   number of sysfs links created to other components from this
> > >    *		device. These will appear in the "connections" group.
> > >    * @has_conns_grp: Have added a "connections" group for sysfs links.
> > > @@ -205,6 +241,7 @@ struct coresight_device {
> > >   	struct coresight_device *def_sink;
> > >   	/* cross trigger handling */
> > >   	struct coresight_device *ect_dev;
> > > +	struct csdev_access access;
> > >   	/* sysfs links between components */
> > >   	int nr_links;
> > >   	bool has_conns_grp;
> > > @@ -326,6 +363,107 @@ struct coresight_ops {
> > >   };
> > >   #if IS_ENABLED(CONFIG_CORESIGHT)
> > > +
> > > +static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa,
> > > +					      u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		return readl_relaxed(csa->base + offset);
> > > +
> > > +	return csa->read(csa, offset, true, false);
> > > +}
> > > +
> > > +static inline u32 csdev_access_read32(struct csdev_access *csa, u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		return readl(csa->base + offset);
> > > +
> > > +	return csa->read(csa, offset, false, false);
> > > +}
> > > +
> > > +static inline void csdev_access_relaxed_write32(struct csdev_access *csa,
> > > +						u32 val,
> > > +						u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		writel_relaxed(val, csa->base + offset);
> > > +	else
> > > +		csa->write(csa, val, offset, true, false);
> > > +}
> > > +
> > > +static inline void csdev_access_write32(struct csdev_access *csa, u32 val, u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		writel(val, csa->base + offset);
> > > +	else
> > > +		csa->write(csa, val, offset, false, false);
> > > +}
> > > +
> > > +#ifdef CONFIG_64BIT
> > > +
> > > +static inline u64 csdev_access_relaxed_read64(struct csdev_access *csa,
> > > +					   u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		return readq_relaxed(csa->base + offset);
> > > +
> > > +	return csa->read(csa, offset, true, true);
> > > +}
> > > +
> > > +static inline u64 csdev_access_read64(struct csdev_access *csa, u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		return readq(csa->base + offset);
> > > +
> > > +	return csa->read(csa, offset, false, true);
> > > +}
> > > +
> > > +static inline void csdev_access_relaxed_write64(struct csdev_access *csa,
> > > +						u64 val,
> > > +						u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		writeq_relaxed(val, csa->base + offset);
> > > +	else
> > > +		csa->write(csa, val, offset, true, true);
> > > +}
> > > +
> > > +static inline void csdev_access_write64(struct csdev_access *csa, u64 val, u32 offset)
> > > +{
> > > +	if (likely(csa->io_mem))
> > > +		writeq(val, csa->base + offset);
> > > +	else
> > > +		csa->write(csa, val, offset, false, true);
> > > +}
> > > +
> > > +#else
> > > +
> > > +static inline u64 csdev_access_relaxed_read64(struct csdev_access *csa,
> > > +					   u32 offset)
> > > +{
> > > +	WARN_ON(1);
> > > +	return 0;
> > > +}
> > > +
> > > +static inline u64 csdev_access_read64(struct csdev_access *csa, u32 offset)
> > > +{
> > > +	WARN_ON(1);
> > > +	return 0;
> > > +}
> > > +
> > > +static inline void csdev_access_relaxed_write64(struct csdev_access *csa,
> > > +						u64 val,
> > > +						u32 offset)
> > > +{
> > > +	WARN_ON(1);
> > > +}
> > > +
> > > +static inline void csdev_access_write64(struct csdev_access *csa, u64 val, u32 offset)
> > > +{
> > > +	WARN_ON(1);
> > > +}
> > > +#endif
> > > +
> > >   extern struct coresight_device *
> > >   coresight_register(struct coresight_desc *desc);
> > >   extern void coresight_unregister(struct coresight_device *csdev);
> > > @@ -343,6 +481,20 @@ extern char *coresight_alloc_device_name(struct coresight_dev_list *devs,
> > >   					 struct device *dev);
> > >   extern bool coresight_loses_context_with_cpu(struct device *dev);
> > > +
> > > +u32 coresight_relaxed_read32(struct coresight_device *csdev, u32 offset);
> > > +u32 coresight_read32(struct coresight_device *csdev, u32 offset);
> > > +void coresight_write32(struct coresight_device *csdev, u32 val, u32 offset);
> > > +void coresight_relaxed_write32(struct coresight_device *csdev,
> > > +			       u32 val,
> > > +			       u32 offset);
> > > +u64 coresight_relaxed_read64(struct coresight_device *csdev, u32 offset);
> > > +u64 coresight_read64(struct coresight_device *csdev, u32 offset);
> > > +void coresight_relaxed_write64(struct coresight_device *csdev,
> > > +			       u64 val, u32 offset);
> > > +void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset);
> > > +
> > > +
> > >   #else
> > >   static inline struct coresight_device *
> > >   coresight_register(struct coresight_desc *desc) { return NULL; }
> > > @@ -369,6 +521,51 @@ static inline bool coresight_loses_context_with_cpu(struct device *dev)
> > >   {
> > >   	return false;
> > >   }
> > > +
> > > +static inline u32 coresight_relaxed_read32(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	WARN_ON_ONCE(1);
> > > +	return 0;
> > > +}
> > > +
> > > +static inline u32 coresight_read32(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	WARN_ON_ONCE(1);
> > > +	return 0;
> > > +}
> > > +
> > > +static inline void coresight_write32(struct coresight_device *csdev, u32 val, u32 offset)
> > > +{
> > > +}
> > > +
> > > +static inline void coresight_relaxed_write32(struct coresight_device *csdev,
> > > +					      u32 val, u32 offset);
> > > +{
> > > +}
> > > +
> > > +static inline u64 coresight_relaxed_read64(struct coresight_device *csdev,
> > > +					   u32 offset)
> > > +{
> > > +	WARN_ON_ONCE(1);
> > > +	return 0;
> > > +}
> > > +
> > > +static inline u64 coresight_read64(struct coresight_device *csdev, u32 offset)
> > > +{
> > > +	WARN_ON_ONCE(1);
> > > +	return 0;
> > > +}
> > > +
> > > +static inline void coresight_relaxed_write64(struct coresight_device *csdev,
> > > +					     u64 val,
> > > +					     u32 offset)
> > > +{
> > > +}
> > > +
> > > +static inline void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset)
> > > +{
> > > +}
> > > +
> > >   #endif
> > >   extern int coresight_get_cpu(struct device *dev);
> > > -- 
> > > 2.24.1
> > > 
>