On Tue, Feb 11, 2020 at 10:58:05AM +0000, Mike Leach wrote:

To allow the connections between coresight components to be represented in sysfs, generic methods for creating sysfs links between two coresight devices are added.

Signed-off-by: Mike Leach mike.leach@linaro.org Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com

---

drivers/hwtracing/coresight/Makefile | 3 +- drivers/hwtracing/coresight/coresight-priv.h | 4 + drivers/hwtracing/coresight/coresight-sysfs.c | 124 ++++++++++++++++++ include/linux/coresight.h | 20 +++ 4 files changed, 150 insertions(+), 1 deletion(-) create mode 100644 drivers/hwtracing/coresight/coresight-sysfs.c

diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile index 0e3e72f0f510..19497d1d92bf 100644 --- a/drivers/hwtracing/coresight/Makefile +++ b/drivers/hwtracing/coresight/Makefile @@ -2,7 +2,8 @@ # # Makefile for CoreSight drivers. # -obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o coresight-platform.o +obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o \

• 	   coresight-platform.o coresight-sysfs.o
  

obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o \ coresight-tmc-etf.o \ coresight-tmc-etr.o diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 1cad642f27aa..a4a658d46045 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -153,6 +153,10 @@ struct coresight_device *coresight_get_sink_by_id(u32 id); struct list_head *coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink); void coresight_release_path(struct list_head *path); +int coresight_add_sysfs_link(struct coresight_sysfs_link *info); +void coresight_remove_sysfs_link(struct coresight_sysfs_link *info); +int coresight_create_conns_sysfs_group(struct coresight_device *csdev); +void coresight_remove_conns_sysfs_group(struct coresight_device *csdev); #ifdef CONFIG_CORESIGHT_SOURCE_ETM3X extern int etm_readl_cp14(u32 off, unsigned int *val); diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c new file mode 100644 index 000000000000..17d565941e5e --- /dev/null +++ b/drivers/hwtracing/coresight/coresight-sysfs.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (c) 2019, Linaro Limited, All rights reserved.
• • Author: Mike Leach mike.leach@linaro.org
• */

+#include <linux/device.h> +#include <linux/kernel.h>

+#include "coresight-priv.h"

+/*

• • Connections group - links attribute.
• • Count of created links between coresight components in the group.
• */

+static ssize_t nr_links_show(struct device *dev,

• 	     struct device_attribute *attr,
  

• 	     char *buf)
  

+{

• struct coresight_device *csdev = to_coresight_device(dev);
• return scnprintf(buf, PAGE_SIZE, "%d\n", csdev->nr_links);

+} +static DEVICE_ATTR_RO(nr_links);

+static struct attribute *coresight_conns_attrs[] = {

• &dev_attr_nr_links.attr,
• NULL,

+};

+static struct attribute_group coresight_conns_group = {

• .attrs = coresight_conns_attrs,
• .name = "connections",

+};

+/*

• • Create connections group for CoreSight devices.
• • This group will then be used to collate the sysfs links between
• • devices.
• */

+int coresight_create_conns_sysfs_group(struct coresight_device *csdev) +{

• int ret = 0;
• if (!csdev)

• return -EINVAL;
  

• ret = sysfs_create_group(&csdev->dev.kobj, &coresight_conns_group);
• if (ret)

• return ret;
  

• csdev->has_conns_grp = true;

The only place coresight_create_conns_sysfs_group() is used is in coresight_register() where an error is returned to driver probe() functions if an error occurs. Have you found places where csdev->has_conns_grp is needed? If not please remove.

• return ret;

+}

+void coresight_remove_conns_sysfs_group(struct coresight_device *csdev) +{

• if (!csdev)

• return;
  

• if (csdev->has_conns_grp) {

• sysfs_remove_group(&csdev->dev.kobj, &coresight_conns_group);
  

• csdev->has_conns_grp = false;
  

• }

+}

+int coresight_add_sysfs_link(struct coresight_sysfs_link *info) +{

• int ret = 0;
• if (!info)

• return -EINVAL;
  

• if (!info->orig || !info->target ||

•    !info->orig_name || !info->target_name)
  

• return -EINVAL;
  

• if (!info->orig->has_conns_grp || !info->target->has_conns_grp)

• return -EINVAL;
  

• /* first link orig->target */
• ret = sysfs_add_link_to_group(&info->orig->dev.kobj,

• 		      coresight_conns_group.name,
  

• 		      &info->target->dev.kobj,
  

• 		      info->orig_name);
  

• if (ret)

• return ret;
  

• /* second link target->orig */
• ret = sysfs_add_link_to_group(&info->target->dev.kobj,

• 		      coresight_conns_group.name,
  

• 		      &info->orig->dev.kobj,
  

• 		      info->target_name);
  

• /* error in second link - remove first - otherwise inc counts */
• if (ret) {

• sysfs_remove_link_from_group(&info->orig->dev.kobj,
  

• 			     coresight_conns_group.name,
  

• 			     info->orig_name);
  

• } else {

• info->orig->nr_links++;
  

• info->target->nr_links++;
  

• }
• return ret;

+}

+void coresight_remove_sysfs_link(struct coresight_sysfs_link *info) +{

• if (!info)

• return;
  

• if (!info->orig || !info->target ||

•    !info->orig_name || !info->target_name)
  

• return;
  

• sysfs_remove_link_from_group(&info->orig->dev.kobj,

• 		     coresight_conns_group.name,
  

• 		     info->orig_name);
  

• sysfs_remove_link_from_group(&info->target->dev.kobj,

• 		     coresight_conns_group.name,
  

• 		     info->target_name);
  

• info->orig->nr_links--;
• info->target->nr_links--;

+} diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 193cc9dbf448..a2ec25e02ca9 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -148,6 +148,20 @@ struct coresight_connection { struct coresight_device *child_dev; }; +/**

• • struct coresight_sysfs_link - representation of a connection in sysfs.
• • @orig: Originating (master) coresight device for the link.
• • @orig_name: Name to use for the link orig->target.
• • @target: Target (slave) coresight device for the link.
• • @target_name: Name to use for the link target->orig.
• */

+struct coresight_sysfs_link {

• struct coresight_device *orig;
• const char *orig_name;
• struct coresight_device *target;
• const char *target_name;

+};

/**

• struct coresight_device - representation of a device as used by the framework
• @pdata: Platform data with device connections associated to this device.

@@ -165,6 +179,9 @@ struct coresight_connection {

• @ea: Device attribute for sink representation under PMU directory.
• @ect_dev: Associated cross trigger device. Not part of the trace data

• path or connections.
  

• • @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.
  */

struct coresight_device { struct coresight_platform_data *pdata; @@ -180,6 +197,9 @@ struct coresight_device { struct dev_ext_attribute *ea; /* cross trigger handling */ struct coresight_device *ect_dev;

• /* sysfs links between components */
• int nr_links;
• bool has_conns_grp;

};

With the above:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

/* -- 2.17.1

On Tue, 25 Feb 2020 at 08:46, Mike Leach mike.leach@linaro.org wrote:

Hi Mathieu,

On Fri, 14 Feb 2020 at 23:17, Mathieu Poirier mathieu.poirier@linaro.org wrote:

...

On Tue, Feb 11, 2020 at 10:58:05AM +0000, Mike Leach wrote:

...

To allow the connections between coresight components to be represented in sysfs, generic methods for creating sysfs links between two coresight devices are added.

Signed-off-by: Mike Leach mike.leach@linaro.org Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com

---

drivers/hwtracing/coresight/Makefile | 3 +- drivers/hwtracing/coresight/coresight-priv.h | 4 + drivers/hwtracing/coresight/coresight-sysfs.c | 124 ++++++++++++++++++ include/linux/coresight.h | 20 +++ 4 files changed, 150 insertions(+), 1 deletion(-) create mode 100644 drivers/hwtracing/coresight/coresight-sysfs.c

diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile index 0e3e72f0f510..19497d1d92bf 100644 --- a/drivers/hwtracing/coresight/Makefile +++ b/drivers/hwtracing/coresight/Makefile @@ -2,7 +2,8 @@ # # Makefile for CoreSight drivers. # -obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o coresight-platform.o +obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o \

•                    coresight-platform.o coresight-sysfs.o
  

obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o \ coresight-tmc-etf.o \ coresight-tmc-etr.o diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 1cad642f27aa..a4a658d46045 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -153,6 +153,10 @@ struct coresight_device *coresight_get_sink_by_id(u32 id); struct list_head *coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink); void coresight_release_path(struct list_head *path); +int coresight_add_sysfs_link(struct coresight_sysfs_link *info); +void coresight_remove_sysfs_link(struct coresight_sysfs_link *info); +int coresight_create_conns_sysfs_group(struct coresight_device *csdev); +void coresight_remove_conns_sysfs_group(struct coresight_device *csdev);

#ifdef CONFIG_CORESIGHT_SOURCE_ETM3X extern int etm_readl_cp14(u32 off, unsigned int *val); diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c new file mode 100644 index 000000000000..17d565941e5e --- /dev/null +++ b/drivers/hwtracing/coresight/coresight-sysfs.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (c) 2019, Linaro Limited, All rights reserved.
• • Author: Mike Leach mike.leach@linaro.org
• */

+#include <linux/device.h> +#include <linux/kernel.h>

+#include "coresight-priv.h"

+/*

• • Connections group - links attribute.
• • Count of created links between coresight components in the group.
• */

+static ssize_t nr_links_show(struct device *dev,

•                      struct device_attribute *attr,
  

•                      char *buf)
  

+{

• struct coresight_device *csdev = to_coresight_device(dev);
  

• return scnprintf(buf, PAGE_SIZE, "%d\n", csdev->nr_links);
  

+} +static DEVICE_ATTR_RO(nr_links);

+static struct attribute *coresight_conns_attrs[] = {

• &dev_attr_nr_links.attr,
  

• NULL,
  

+};

+static struct attribute_group coresight_conns_group = {

• .attrs = coresight_conns_attrs,
  

• .name = "connections",
  

+};

+/*

• • Create connections group for CoreSight devices.
• • This group will then be used to collate the sysfs links between
• • devices.
• */

+int coresight_create_conns_sysfs_group(struct coresight_device *csdev) +{

• int ret = 0;
  

• if (!csdev)
  

•         return -EINVAL;
  

• ret = sysfs_create_group(&csdev->dev.kobj, &coresight_conns_group);
  

• if (ret)
  

•         return ret;
  

• csdev->has_conns_grp = true;
  

The only place coresight_create_conns_sysfs_group() is used is in coresight_register() where an error is returned to driver probe() functions if an error occurs. Have you found places where csdev->has_conns_grp is needed? If not please remove.

There is a sequence of calls in coresight_register() which occur after the coresight_create_conns_sysfs_group() - any one of which may throw an error resulting in an immediate coresight_unregister() and hence coresight_release_platform_data() => coresight_remove_conns_sysfs_group(). There is also an alternate path through coresight_register() which also results in coresight_release_platform_data() occurring before we have created the group. The flag ensures that both paths clean up the sysfs connection data correctly and safely.

I see the real problem is with the WARN() that is thrown in sysfs_remove_group() when a group has not been created, and we can't have that. I think what you did is fine.

Mathieu

Regards

Mike

...

...

• return ret;
  

+}

+void coresight_remove_conns_sysfs_group(struct coresight_device *csdev) +{

• if (!csdev)
  

•         return;
  

• if (csdev->has_conns_grp) {
  

•         sysfs_remove_group(&csdev->dev.kobj, &coresight_conns_group);
  

•         csdev->has_conns_grp = false;
  

• }
  

+}

+int coresight_add_sysfs_link(struct coresight_sysfs_link *info) +{

• int ret = 0;
  

• if (!info)
  

•         return -EINVAL;
  

• if (!info->orig || !info->target ||
  

•     !info->orig_name || !info->target_name)
  

•         return -EINVAL;
  

• if (!info->orig->has_conns_grp || !info->target->has_conns_grp)
  

•         return -EINVAL;
  

• /* first link orig->target */
  

• ret = sysfs_add_link_to_group(&info->orig->dev.kobj,
  

•                               coresight_conns_group.name,
  

•                               &info->target->dev.kobj,
  

•                               info->orig_name);
  

• if (ret)
  

•         return ret;
  

• /* second link target->orig */
  

• ret = sysfs_add_link_to_group(&info->target->dev.kobj,
  

•                               coresight_conns_group.name,
  

•                               &info->orig->dev.kobj,
  

•                               info->target_name);
  

• /* error in second link - remove first - otherwise inc counts */
  

• if (ret) {
  

•         sysfs_remove_link_from_group(&info->orig->dev.kobj,
  

•                                      coresight_conns_group.name,
  

•                                      info->orig_name);
  

• } else {
  

•         info->orig->nr_links++;
  

•         info->target->nr_links++;
  

• }
  

• return ret;
  

+}

+void coresight_remove_sysfs_link(struct coresight_sysfs_link *info) +{

• if (!info)
  

•         return;
  

• if (!info->orig || !info->target ||
  

•     !info->orig_name || !info->target_name)
  

•         return;
  

• sysfs_remove_link_from_group(&info->orig->dev.kobj,
  

•                              coresight_conns_group.name,
  

•                              info->orig_name);
  

• sysfs_remove_link_from_group(&info->target->dev.kobj,
  

•                              coresight_conns_group.name,
  

•                              info->target_name);
  

• info->orig->nr_links--;
  

• info->target->nr_links--;
  

+} diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 193cc9dbf448..a2ec25e02ca9 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -148,6 +148,20 @@ struct coresight_connection { struct coresight_device *child_dev; };

+/**

• • struct coresight_sysfs_link - representation of a connection in sysfs.
• • @orig: Originating (master) coresight device for the link.
• • @orig_name: Name to use for the link orig->target.
• • @target: Target (slave) coresight device for the link.
• • @target_name: Name to use for the link target->orig.
• */

+struct coresight_sysfs_link {

• struct coresight_device *orig;
  

• const char *orig_name;
  

• struct coresight_device *target;
  

• const char *target_name;
  

+};

/**

• struct coresight_device - representation of a device as used by the framework
• @pdata: Platform data with device connections associated to this device.

@@ -165,6 +179,9 @@ struct coresight_connection {

• @ea: Device attribute for sink representation under PMU directory.
• @ect_dev: Associated cross trigger device. Not part of the trace data

•       path or connections.
  

• • @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.
  */

struct coresight_device { struct coresight_platform_data *pdata; @@ -180,6 +197,9 @@ struct coresight_device { struct dev_ext_attribute *ea; /* cross trigger handling */ struct coresight_device *ect_dev;

• /* sysfs links between components */
  

• int nr_links;
  

• bool has_conns_grp;
  

};

With the above:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

...

/*

2.17.1

-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK

Hi Mike,

On Tue, Feb 11, 2020 at 10:58:06AM +0000, Mike Leach wrote:

From: Suzuki K Poulose suzuki.poulose@arm.com

Coresight device connections are a bit complicated and is not exposed currently to the user. One has to look at the platform descriptions (DT bindings or ACPI bindings) to make an understanding. Given the new naming scheme, it will be helpful to have this information to choose the appropriate devices for tracing. This patch exposes the device connections via links in the sysfs directories.

e.g, for a connection devA[OutputPort_X] -> devB[InputPort_Y] is represented as two symlinks:

/sys/bus/coresight/.../devA/out:X -> /sys/bus/coresight/.../devB /sys/bus/coresight/.../devB/in:Y -> /sys/bus/coresight/.../devA

Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com

Revised to use the generic sysfs links functions & link structures. Provides a connections sysfs group to hold the links.

Co-developed-by: Mike Leach mike.leach@linaro.org Signed-off-by: Mike Leach mike.leach@linaro.org

Because this patch is "From:" Suzuki, this should be:

Co-developed-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Mike Leach mike.leach@linaro.org

You can expand on Suzuki's contribution or the modifications you've done to it in the changelog.

With the above:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

---

drivers/hwtracing/coresight/coresight-priv.h | 5 ++ drivers/hwtra cing/coresight/coresight-sysfs.c | 80 +++++++++++++++++++ drivers/hwtracing/coresight/coresight.c | 46 ++++++++--- include/linux/coresight.h | 2 + 4 files changed, 121 insertions(+), 12 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index a4a658d46045..5a36f0f50899 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -157,6 +157,11 @@ int coresight_add_sysfs_link(struct coresight_sysfs_link *info); void coresight_remove_sysfs_link(struct coresight_sysfs_link *info); int coresight_create_conns_sysfs_group(struct coresight_device *csdev); void coresight_remove_conns_sysfs_group(struct coresight_device *csdev); +int coresight_make_links(struct coresight_device *orig,

• 	 struct coresight_connection *conn,
  

• 	 struct coresight_device *target);
  

+void coresight_remove_links(struct coresight_device *orig,

• 	    struct coresight_connection *conn);
  

#ifdef CONFIG_CORESIGHT_SOURCE_ETM3X extern int etm_readl_cp14(u32 off, unsigned int *val); diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c index 17d565941e5e..0f18332b9f19 100644 --- a/drivers/hwtracing/coresight/coresight-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-sysfs.c @@ -122,3 +122,83 @@ void coresight_remove_sysfs_link(struct coresight_sysfs_link *info) info->orig->nr_links--; info->target->nr_links--; }

+/*

• • coresight_make_links: Make a link for a connection from a @orig
• • device to @target, represented by @conn.
• • e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
• • as two symbolic links :
• • /sys/.../devOrig/out:X -> /sys/.../devTarget/
• • /sys/.../devTarget/in:Y -> /sys/.../devOrig/
• • The link names are allocated for a device where it appears. i.e, the
• • "out" link on the master and "in" link on the slave device.
• • The link info is stored in the connection record for avoiding
• • the reconstruction of names for removal.
• */

+int coresight_make_links(struct coresight_device *orig,

• 	 struct coresight_connection *conn,
  

• 	 struct coresight_device *target)
  

+{

• int ret = -ENOMEM;
• char *outs = NULL, *ins = NULL;
• struct coresight_sysfs_link *link = NULL;
• do {

• outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
  

• 		      "out:%d", conn->outport);
  

• if (!outs)
  

• 	break;
  

• ins = devm_kasprintf(&target->dev, GFP_KERNEL,
  

• 		     "in:%d", conn->child_port);
  

• if (!ins)
  

• 	break;
  

• link = devm_kzalloc(&orig->dev,
  

• 		    sizeof(struct coresight_sysfs_link),
  

• 		    GFP_KERNEL);
  

• if (!link)
  

• 	break;
  

• link->orig = orig;
  

• link->target = target;
  

• link->orig_name = outs;
  

• link->target_name = ins;
  

• ret = coresight_add_sysfs_link(link);
  

• if (ret)
  

• 	break;
  

• conn->link = link;
  

• /*
  

•  * Install the device connection. This also indicates that
  

•  * the links are operational on both ends.
  

•  */
  

• conn->child_dev = target;
  

• return 0;
  

• } while (0);
• return ret;

+}

+/*

• • coresight_remove_links: Remove the sysfs links for a given connection @conn,
• • from @orig device to @target device. See coresight_make_links() for more
• • details.
• */

+void coresight_remove_links(struct coresight_device *orig,

• 	    struct coresight_connection *conn)
  

+{

• if (!orig || !conn->link)

• return;
  

• coresight_remove_sysfs_link(conn->link);
• devm_kfree(&conn->child_dev->dev, conn->link->target_name);
• devm_kfree(&orig->dev, conn->link->orig_name);
• devm_kfree(&orig->dev, conn->link);
• conn->link = NULL;
• conn->child_dev = NULL;

+} diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index 07f66a3968f1..4f10cfa9dc18 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -1031,7 +1031,7 @@ static void coresight_device_release(struct device *dev) static int coresight_orphan_match(struct device *dev, void *data) {

• int i;

• int i, ret = 0; bool still_orphan = false; struct coresight_device *csdev, *i_csdev; struct coresight_connection *conn;

@@ -1056,19 +1056,23 @@ static int coresight_orphan_match(struct device *dev, void *data) /* We have found at least one orphan connection */ if (conn->child_dev == NULL) { /* Does it match this newly added device? */

• 	if (conn->child_fwnode == csdev->dev.fwnode)
  

• 		conn->child_dev = csdev;
  

• 	else
  

• 	if (conn->child_fwnode == csdev->dev.fwnode) {
  

• 		ret = coresight_make_links(i_csdev,
  

• 					   conn, csdev);
  

• 		if (ret)
  

• 			return ret;
  

• 	} else {
  	/* This component still has an orphan */
  	still_orphan = true;
  

• 	}
  

  } }

i_csdev->orphan = still_orphan; /*

• * Returning '0' ensures that all known component on the
  

• * bus will be checked.
  

• * Returning '0' in case we didn't encounter any error,
  

• * ensures that all known component on the bus will be checked.
  

  */ return 0;

} @@ -1082,15 +1086,21 @@ static int coresight_fixup_orphan_conns(struct coresight_device *csdev) static int coresight_fixup_device_conns(struct coresight_device *csdev) {

• int i;

• int i, ret = 0;

for (i = 0; i < csdev->pdata->nr_outport; i++) { struct coresight_connection *conn = &csdev->pdata->conns[i]; conn->child_dev = coresight_find_csdev_by_fwnode(conn->child_fwnode);

• if (!conn->child_dev)
  

• if (conn->child_dev) {
  

• 	ret = coresight_make_links(csdev, conn,
  

• 				   conn->child_dev);
  

• 	if (ret)
  

• 		break;
  

• } else {
  csdev->orphan = true;
  

• }
  

  }

return 0; @@ -1121,7 +1131,7 @@ static int coresight_remove_match(struct device *dev, void *data) if (csdev->dev.fwnode == conn->child_fwnode) { iterator->orphan = true;

• 	conn->child_dev = NULL;
  

• 	coresight_remove_links(iterator, conn);
  /*
   * Drop the reference to the handle for the remote
   * device acquired in parsing the connections from
  

@@ -1215,13 +1225,23 @@ void coresight_release_platform_data(struct coresight_device *csdev, struct coresight_platform_data *pdata) { int i;

• struct coresight_connection *conns = pdata->conns;

for (i = 0; i < pdata->nr_outport; i++) {

• if (pdata->conns[i].child_fwnode) {
  

• 	fwnode_handle_put(pdata->conns[i].child_fwnode);
  

• /* If we have made the links, remove them now */
  

• if (csdev && conns[i].child_dev)
  

• 	coresight_remove_links(csdev, &conns[i]);
  

• /*
  

•  * Drop the refcount and clear the handle as this device
  

•  * is going away
  

•  */
  

• if (conns[i].child_fwnode) {
  

• 	fwnode_handle_put(conns[i].child_fwnode);
  pdata->conns[i].child_fwnode = NULL;
  

  } }
• if (csdev)

• coresight_remove_conns_sysfs_group(csdev);
  

} struct coresight_device *coresight_register(struct coresight_desc *desc) @@ -1303,7 +1323,9 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) mutex_lock(&coresight_mutex);

• ret = coresight_fixup_device_conns(csdev);

• ret = coresight_create_conns_sysfs_group(csdev);
• if (!ret)

• ret = coresight_fixup_device_conns(csdev);
  

  if (!ret) ret = coresight_fixup_orphan_conns(csdev); if (!ret)

diff --git a/include/linux/coresight.h b/include/linux/coresight.h index a2ec25e02ca9..ccd17304d7bd 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -140,12 +140,14 @@ struct coresight_desc {

• @chid_fwnode: remote component's fwnode handle.
• @child_dev: a @coresight_device representation of the component connected to @outport.

• • @link: Representation of the connection as a sysfs link.
  */

struct coresight_connection { int outport; int child_port; struct fwnode_handle *child_fwnode; struct coresight_device *child_dev;

• struct coresight_sysfs_link *link;

}; /** -- 2.17.1

On Wed, Feb 26, 2020 at 02:32:16PM +0000, Mike Leach wrote:

Hi Mathieu,

On Fri, 14 Feb 2020 at 22:31, Mathieu Poirier mathieu.poirier@linaro.org wrote:

...

Hi Mike,

On Tue, Feb 11, 2020 at 10:58:06AM +0000, Mike Leach wrote:

...

From: Suzuki K Poulose suzuki.poulose@arm.com

Coresight device connections are a bit complicated and is not exposed currently to the user. One has to look at the platform descriptions (DT bindings or ACPI bindings) to make an understanding. Given the new naming scheme, it will be helpful to have this information to choose the appropriate devices for tracing. This patch exposes the device connections via links in the sysfs directories.

e.g, for a connection devA[OutputPort_X] -> devB[InputPort_Y] is represented as two symlinks:

/sys/bus/coresight/.../devA/out:X -> /sys/bus/coresight/.../devB /sys/bus/coresight/.../devB/in:Y -> /sys/bus/coresight/.../devA

Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com

Revised to use the generic sysfs links functions & link structures. Provides a connections sysfs group to hold the links.

Co-developed-by: Mike Leach mike.leach@linaro.org Signed-off-by: Mike Leach mike.leach@linaro.org

Because this patch is "From:" Suzuki, this should be:

Co-developed-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Mike Leach mike.leach@linaro.org

if I do the above then checkpatch.pl:-

WARNING: Co-developed-by: should not be used to attribute nominal patch author 'Suzuki K Poulose suzuki.poulose@arm.com' #25: Co-developed-by: Suzuki K Poulose suzuki.poulose@arm.com WARNING: Co-developed-by and Signed-off-by: name/email do not match #25: Co-developed-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Mike Leach mike.leach@linaro.org

Got that - thanks

Regards

Mike

...

You can expand on Suzuki's contribution or the modifications you've done to it in the changelog.

With the above:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

...

---

drivers/hwtracing/coresight/coresight-priv.h | 5 ++ drivers/hwtra cing/coresight/coresight-sysfs.c | 80 +++++++++++++++++++ drivers/hwtracing/coresight/coresight.c | 46 ++++++++--- include/linux/coresight.h | 2 + 4 files changed, 121 insertions(+), 12 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index a4a658d46045..5a36f0f50899 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -157,6 +157,11 @@ int coresight_add_sysfs_link(struct coresight_sysfs_link *info); void coresight_remove_sysfs_link(struct coresight_sysfs_link *info); int coresight_create_conns_sysfs_group(struct coresight_device *csdev); void coresight_remove_conns_sysfs_group(struct coresight_device *csdev); +int coresight_make_links(struct coresight_device *orig,

•                  struct coresight_connection *conn,
  

•                  struct coresight_device *target);
  

+void coresight_remove_links(struct coresight_device *orig,

•                     struct coresight_connection *conn);
  
  

#ifdef CONFIG_CORESIGHT_SOURCE_ETM3X extern int etm_readl_cp14(u32 off, unsigned int *val); diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c index 17d565941e5e..0f18332b9f19 100644 --- a/drivers/hwtracing/coresight/coresight-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-sysfs.c @@ -122,3 +122,83 @@ void coresight_remove_sysfs_link(struct coresight_sysfs_link *info) info->orig->nr_links--; info->target->nr_links--; }

+/*

• • coresight_make_links: Make a link for a connection from a @orig
• • device to @target, represented by @conn.
• • e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
• • as two symbolic links :
• • /sys/.../devOrig/out:X -> /sys/.../devTarget/
• • /sys/.../devTarget/in:Y -> /sys/.../devOrig/
• • The link names are allocated for a device where it appears. i.e, the
• • "out" link on the master and "in" link on the slave device.
• • The link info is stored in the connection record for avoiding
• • the reconstruction of names for removal.
• */

+int coresight_make_links(struct coresight_device *orig,

•                  struct coresight_connection *conn,
  

•                  struct coresight_device *target)
  

+{

• int ret = -ENOMEM;
  

• char *outs = NULL, *ins = NULL;
  

• struct coresight_sysfs_link *link = NULL;
  

• do {
  

•         outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
  

•                               "out:%d", conn->outport);
  

•         if (!outs)
  

•                 break;
  

•         ins = devm_kasprintf(&target->dev, GFP_KERNEL,
  

•                              "in:%d", conn->child_port);
  

•         if (!ins)
  

•                 break;
  

•         link = devm_kzalloc(&orig->dev,
  

•                             sizeof(struct coresight_sysfs_link),
  

•                             GFP_KERNEL);
  

•         if (!link)
  

•                 break;
  

•         link->orig = orig;
  

•         link->target = target;
  

•         link->orig_name = outs;
  

•         link->target_name = ins;
  

•         ret = coresight_add_sysfs_link(link);
  

•         if (ret)
  

•                 break;
  

•         conn->link = link;
  

•         /*
  

•          * Install the device connection. This also indicates that
  

•          * the links are operational on both ends.
  

•          */
  

•         conn->child_dev = target;
  

•         return 0;
  

• } while (0);
  

• return ret;
  

+}

+/*

• • coresight_remove_links: Remove the sysfs links for a given connection @conn,
• • from @orig device to @target device. See coresight_make_links() for more
• • details.
• */

+void coresight_remove_links(struct coresight_device *orig,

•                     struct coresight_connection *conn)
  

+{

• if (!orig || !conn->link)
  

•         return;
  

• coresight_remove_sysfs_link(conn->link);
  

• devm_kfree(&conn->child_dev->dev, conn->link->target_name);
  

• devm_kfree(&orig->dev, conn->link->orig_name);
  

• devm_kfree(&orig->dev, conn->link);
  

• conn->link = NULL;
  

• conn->child_dev = NULL;
  

+} diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index 07f66a3968f1..4f10cfa9dc18 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -1031,7 +1031,7 @@ static void coresight_device_release(struct device *dev)

static int coresight_orphan_match(struct device *dev, void *data) {

• int i;
  

• int i, ret = 0;
  bool still_orphan = false;
  struct coresight_device *csdev, *i_csdev;
  struct coresight_connection *conn;
  

@@ -1056,19 +1056,23 @@ static int coresight_orphan_match(struct device *dev, void *data) /* We have found at least one orphan connection */ if (conn->child_dev == NULL) { /* Does it match this newly added device? */

•                 if (conn->child_fwnode == csdev->dev.fwnode)
  

•                         conn->child_dev = csdev;
  

•                 else
  

•                 if (conn->child_fwnode == csdev->dev.fwnode) {
  

•                         ret = coresight_make_links(i_csdev,
  

•                                                    conn, csdev);
  

•                         if (ret)
  

•                                 return ret;
  

•                 } else {
                          /* This component still has an orphan */
                          still_orphan = true;
  

•                 }
          }
  }
  
  i_csdev->orphan = still_orphan;
  
  /*
  

•  * Returning '0' ensures that all known component on the
  

•  * bus will be checked.
  

•  * Returning '0' in case we didn't encounter any error,
  

•  * ensures that all known component on the bus will be checked.
   */
  return 0;
  

} @@ -1082,15 +1086,21 @@ static int coresight_fixup_orphan_conns(struct coresight_device *csdev)

static int coresight_fixup_device_conns(struct coresight_device *csdev) {

• int i;
  

• int i, ret = 0;
  
  for (i = 0; i < csdev->pdata->nr_outport; i++) {
          struct coresight_connection *conn = &csdev->pdata->conns[i];
  
          conn->child_dev =
                  coresight_find_csdev_by_fwnode(conn->child_fwnode);
  

•         if (!conn->child_dev)
  

•         if (conn->child_dev) {
  

•                 ret = coresight_make_links(csdev, conn,
  

•                                            conn->child_dev);
  

•                 if (ret)
  

•                         break;
  

•         } else {
                  csdev->orphan = true;
  

•         }
  }
  
  return 0;
  

@@ -1121,7 +1131,7 @@ static int coresight_remove_match(struct device *dev, void *data)

          if (csdev->dev.fwnode == conn->child_fwnode) {
                  iterator->orphan = true;

•                 conn->child_dev = NULL;
  

•                 coresight_remove_links(iterator, conn);
                  /*
                   * Drop the reference to the handle for the remote
                   * device acquired in parsing the connections from
  

@@ -1215,13 +1225,23 @@ void coresight_release_platform_data(struct coresight_device *csdev, struct coresight_platform_data *pdata) { int i;

• struct coresight_connection *conns = pdata->conns;
  
  for (i = 0; i < pdata->nr_outport; i++) {
  

•         if (pdata->conns[i].child_fwnode) {
  

•                 fwnode_handle_put(pdata->conns[i].child_fwnode);
  

•         /* If we have made the links, remove them now */
  

•         if (csdev && conns[i].child_dev)
  

•                 coresight_remove_links(csdev, &conns[i]);
  

•         /*
  

•          * Drop the refcount and clear the handle as this device
  

•          * is going away
  

•          */
  

•         if (conns[i].child_fwnode) {
  

•                 fwnode_handle_put(conns[i].child_fwnode);
                  pdata->conns[i].child_fwnode = NULL;
          }
  }
  

• if (csdev)
  

•         coresight_remove_conns_sysfs_group(csdev);
  

}

struct coresight_device *coresight_register(struct coresight_desc *desc) @@ -1303,7 +1323,9 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)

  mutex_lock(&coresight_mutex);

• ret = coresight_fixup_device_conns(csdev);
  

• ret = coresight_create_conns_sysfs_group(csdev);
  

• if (!ret)
  

•         ret = coresight_fixup_device_conns(csdev);
  if (!ret)
          ret = coresight_fixup_orphan_conns(csdev);
  if (!ret)
  

diff --git a/include/linux/coresight.h b/include/linux/coresight.h index a2ec25e02ca9..ccd17304d7bd 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -140,12 +140,14 @@ struct coresight_desc {

• @chid_fwnode: remote component's fwnode handle.
• @child_dev: a @coresight_device representation of the component connected to @outport.

• • @link: Representation of the connection as a sysfs link.
  */

struct coresight_connection { int outport; int child_port; struct fwnode_handle *child_fwnode; struct coresight_device *child_dev;

• struct coresight_sysfs_link *link;
  

};

/**

2.17.1

-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK

On Tue, Feb 11, 2020 at 10:58:07AM +0000, Mike Leach wrote:

Adds in sysfs links for connections where the connected device is another coresight device. This allows examination of the coresight topology.

Non-coresight connections remain just as a reference name.

Signed-off-by: Mike Leach mike.leach@linaro.org

drivers/hwtracing/coresight/coresight-cti.c | 41 ++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c index 9e18e176831c..f620e9460e7d 100644 --- a/drivers/hwtracing/coresight/coresight-cti.c +++ b/drivers/hwtracing/coresight/coresight-cti.c @@ -441,6 +441,37 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op, return err; } +static void cti_add_sysfs_link(struct cti_drvdata *drvdata,

• 	       struct cti_trig_con *tc)
  

+{

• struct coresight_sysfs_link link_info;
• link_info.orig = drvdata->csdev;
• link_info.orig_name = tc->con_dev_name;
• link_info.target = tc->con_dev;
• link_info.target_name = dev_name(&drvdata->csdev->dev);
• coresight_add_sysfs_link(&link_info);

I understand there isn't much to do if a problem occurs so just catch the error and add a comment to assert you're doing this on purpose.

+}

+static void cti_remove_all_sysfs_links(struct cti_drvdata *drvdata) +{

• struct cti_trig_con *tc;
• struct cti_device *ctidev = &drvdata->ctidev;
• struct coresight_sysfs_link link_info;
• /* origin device and target link name constant for this cti */
• link_info.orig = drvdata->csdev;
• link_info.target_name = dev_name(&drvdata->csdev->dev);
• list_for_each_entry(tc, &ctidev->trig_cons, node) {

• if (tc->con_dev) {
  

• 	link_info.target = tc->con_dev;
  

• 	link_info.orig_name = tc->con_dev_name;
  

• 	coresight_remove_sysfs_link(&link_info);
  

• }
  

• }

+}

/*

• Look for a matching connection device name in the list of connections.
• If found then swap in the csdev name, set trig con association pointer

@@ -452,6 +483,8 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name, { struct cti_trig_con *tc; const char *csdev_name;

• struct cti_drvdata *drvdata = container_of(ctidev, struct cti_drvdata,

• 				   ctidev);
  

list_for_each_entry(tc, &ctidev->trig_cons, node) { if (tc->con_dev_name) { @@ -462,6 +495,7 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name, devm_kstrdup(&csdev->dev, csdev_name, GFP_KERNEL); tc->con_dev = csdev;

• 		cti_add_sysfs_link(drvdata, tc);
  	return true;
  }
  

  }

@@ -546,10 +580,12 @@ static void cti_update_conn_xrefs(struct cti_drvdata *drvdata) struct cti_device *ctidev = &drvdata->ctidev; list_for_each_entry(tc, &ctidev->trig_cons, node) {

• if (tc->con_dev)
  

• if (tc->con_dev) {
  /* set tc->con_dev->ect_dev */
  coresight_set_assoc_ectdev_mutex(tc->con_dev,
  				 drvdata->csdev);
  

• 	cti_add_sysfs_link(drvdata, tc);
  

• }
  

  }

} @@ -602,6 +638,9 @@ static void cti_device_release(struct device *dev) mutex_lock(&ect_mutex); cti_remove_conn_xrefs(drvdata);

• /* clear the dynamic sysfs associate with connections */

s/associate/associated

• cti_remove_all_sysfs_links(drvdata);
• /* remove from the list */ list_for_each_entry_safe(ect_item, ect_tmp, &ect_net, node) { if (ect_item == drvdata) {

With the above:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

-- 2.17.1

On Wed, Feb 26, 2020 at 01:37:17PM +0000, Mike Leach wrote:

Hi Mathieu,

On Fri, 14 Feb 2020 at 22:58, Mathieu Poirier mathieu.poirier@linaro.org wrote:

...

On Tue, Feb 11, 2020 at 10:58:07AM +0000, Mike Leach wrote:

...

Adds in sysfs links for connections where the connected device is another coresight device. This allows examination of the coresight topology.

Non-coresight connections remain just as a reference name.

Signed-off-by: Mike Leach mike.leach@linaro.org

drivers/hwtracing/coresight/coresight-cti.c | 41 ++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c index 9e18e176831c..f620e9460e7d 100644 --- a/drivers/hwtracing/coresight/coresight-cti.c +++ b/drivers/hwtracing/coresight/coresight-cti.c @@ -441,6 +441,37 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op, return err; }

+static void cti_add_sysfs_link(struct cti_drvdata *drvdata,

•                        struct cti_trig_con *tc)
  

+{

• struct coresight_sysfs_link link_info;
  

• link_info.orig = drvdata->csdev;
  

• link_info.orig_name = tc->con_dev_name;
  

• link_info.target = tc->con_dev;
  

• link_info.target_name = dev_name(&drvdata->csdev->dev);
  

• coresight_add_sysfs_link(&link_info);
  

I understand there isn't much to do if a problem occurs so just catch the error and add a comment to assert you're doing this on purpose.

When I revisited this code I saw an imbalance between the case where the CTI is created first and the associated CSdev is created first. The result could be shutdown path where the CTI removes sysfs links after the csdev has been removed - which really shouldn't happen. Also we could try to remove a sysfs link that we failed to set in the first place - again not ideal

I've reworked this code to fix this, and now if the sysfs link fails to be set, then we do not set the association between CTI and csdev components.

Ok

This is not sufficient to fail either component from registering, as we may have successfully registered previous associations with the same CTI.

That is also my opinion.

It seems unlikely that the sysfs link could fail, but if it does, is it worth using a dev_warn() to at least log the failure?

Yes, that would surely be helpful.

Regards

Mike

...

...

+}

+static void cti_remove_all_sysfs_links(struct cti_drvdata *drvdata) +{

• struct cti_trig_con *tc;
  

• struct cti_device *ctidev = &drvdata->ctidev;
  

• struct coresight_sysfs_link link_info;
  

• /* origin device and target link name constant for this cti */
  

• link_info.orig = drvdata->csdev;
  

• link_info.target_name = dev_name(&drvdata->csdev->dev);
  

• list_for_each_entry(tc, &ctidev->trig_cons, node) {
  

•         if (tc->con_dev) {
  

•                 link_info.target = tc->con_dev;
  

•                 link_info.orig_name = tc->con_dev_name;
  

•                 coresight_remove_sysfs_link(&link_info);
  

•         }
  

• }
  

+}

/*

• Look for a matching connection device name in the list of connections.
• If found then swap in the csdev name, set trig con association pointer

@@ -452,6 +483,8 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name, { struct cti_trig_con *tc; const char *csdev_name;

• struct cti_drvdata *drvdata = container_of(ctidev, struct cti_drvdata,
  

•                                            ctidev);
  
  list_for_each_entry(tc, &ctidev->trig_cons, node) {
          if (tc->con_dev_name) {
  

@@ -462,6 +495,7 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name, devm_kstrdup(&csdev->dev, csdev_name, GFP_KERNEL); tc->con_dev = csdev;

•                         cti_add_sysfs_link(drvdata, tc);
                          return true;
                  }
          }
  

@@ -546,10 +580,12 @@ static void cti_update_conn_xrefs(struct cti_drvdata *drvdata) struct cti_device *ctidev = &drvdata->ctidev;

  list_for_each_entry(tc, &ctidev->trig_cons, node) {

•         if (tc->con_dev)
  

•         if (tc->con_dev) {
                  /* set tc->con_dev->ect_dev */
                  coresight_set_assoc_ectdev_mutex(tc->con_dev,
                                                   drvdata->csdev);
  

•                 cti_add_sysfs_link(drvdata, tc);
  

•         }
  }
  

}

@@ -602,6 +638,9 @@ static void cti_device_release(struct device *dev) mutex_lock(&ect_mutex); cti_remove_conn_xrefs(drvdata);

• /* clear the dynamic sysfs associate with connections */
  

s/associate/associated

...

• cti_remove_all_sysfs_links(drvdata);
  

• /* remove from the list */
  list_for_each_entry_safe(ect_item, ect_tmp, &ect_net, node) {
          if (ect_item == drvdata) {
  

With the above:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

...

-- 2.17.1

-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK

On Tue, Feb 11, 2020 at 10:58:08AM +0000, Mike Leach wrote:

Update the CoreSight documents to describe the new connections directory and the links between CoreSight devices in this directory.

Signed-off-by: Mike Leach mike.leach@linaro.org

.../trace/coresight/coresight-ect.rst | 5 +- Documentation/trace/coresight/coresight.rst | 85 +++++++++++++++++++ 2 files changed, 89 insertions(+), 1 deletion(-)

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

diff --git a/Documentation/trace/coresight/coresight-ect.rst b/Documentation/trace/coresight/coresight-ect.rst index 067cee91c857..3539af895832 100644 --- a/Documentation/trace/coresight/coresight-ect.rst +++ b/Documentation/trace/coresight/coresight-ect.rst @@ -71,7 +71,7 @@ capable of generating or using trigger signals.::

...

$ ls /sys/bus/coresight/devices/etm0/cti_cpu0

channels ctmid enable nr_trigger_cons mgmt power regs subsystem

• triggers0 triggers1 uevent

• connections triggers0 triggers1 uevent

*Key file items are:-* * ``enable``: enables/disables the CTI. @@ -84,6 +84,9 @@ capable of generating or using trigger signals.:: * ``channels``: Contains the channel API - CTI main programming interface. * ``regs``: Gives access to the raw programmable CTI regs. * ``mgmt``: the standard CoreSight management registers.

• • ``connections``: Links to connected *CoreSight* devices. The number of

• links can be 0 to ``nr_trigger_cons``. Actual number given by ``nr_links``
  

• in this directory.
  

triggers<N> directories diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst index 108600ee1e12..0b73acb44efa 100644 --- a/Documentation/trace/coresight/coresight.rst +++ b/Documentation/trace/coresight/coresight.rst @@ -241,6 +241,91 @@ to the newer scheme, to give a confirmation that what you see on your system is not unexpected. One must use the "names" as they appear on the system under specified locations. +Topology Representation +-----------------------

+Each CoreSight component has a ``connections`` directory which will contain +links to other CoreSight components. This allows the user to explore the trace +topology and for larger systems, determine the most appropriate sink for a +given source. The connection information can also be used to establish +which CTI devices are connected to a given component. This directory contains a +``nr_links`` attribute detailing the number of links in the directory.

+For an ETM source, in this case ``etm0`` on a Juno platform, a typical +arrangement will be::

• linaro-developer:~# ls - l /sys/bus/coresight/devices/etm0/connections
• <file details> cti_cpu0 -> ../../../23020000.cti/cti_cpu0
• <file details> nr_links
• <file details> out:0 -> ../../../230c0000.funnel/funnel2

+Following the out port to ``funnel2``::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel2/connections
• <file details> in:0 -> ../../../23040000.etm/etm0
• <file details> in:1 -> ../../../23140000.etm/etm3
• <file details> in:2 -> ../../../23240000.etm/etm4
• <file details> in:3 -> ../../../23340000.etm/etm5
• <file details> nr_links
• <file details> out:0 -> ../../../20040000.funnel/funnel0

+And again to ``funnel0``::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel0/connections
• <file details> in:0 -> ../../../220c0000.funnel/funnel1
• <file details> in:1 -> ../../../230c0000.funnel/funnel2
• <file details> nr_links
• <file details> out:0 -> ../../../20010000.etf/tmc_etf0

+Finding the first sink ``tmc_etf0``. This can be used to collect data +as a sink, or as a link to propagate further along the chain::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/tmc_etf0/connections
• <file details> cti_sys0 -> ../../../20020000.cti/cti_sys0
• <file details> in:0 -> ../../../20040000.funnel/funnel0
• <file details> nr_links
• <file details> out:0 -> ../../../20150000.funnel/funnel4

+via ``funnel4``::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel4/connections
• <file details> in:0 -> ../../../20010000.etf/tmc_etf0
• <file details> in:1 -> ../../../20140000.etf/tmc_etf1
• <file details> nr_links
• <file details> out:0 -> ../../../20120000.replicator/replicator0

+and a ``replicator0``::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/replicator0/connections
• <file details> in:0 -> ../../../20150000.funnel/funnel4
• <file details> nr_links
• <file details> out:0 -> ../../../20030000.tpiu/tpiu0
• <file details> out:1 -> ../../../20070000.etr/tmc_etr0

+Arriving at the final sink in the chain, ``tmc_etr0``::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/tmc_etr0/connections
• <file details> cti_sys0 -> ../../../20020000.cti/cti_sys0
• <file details> in:0 -> ../../../20120000.replicator/replicator0
• <file details> nr_links

+As described below, when using sysfs it is sufficient to enable a sink and +a source for successful trace. The framework will correctly enable all +intermediate links as required.

+Note: ``cti_sys0`` appears in two of the connections lists above. +CTIs can connect to multiple devices and are arranged in a star topology +via the CTM. See (:doc:`coresight-ect`) [#fourth]_ for further details. +Looking at this device we see 4 connections::

• linaro-developer:~# ls -l /sys/bus/coresight/devices/cti_sys0/connections
• <file details> nr_links
• <file details> stm0 -> ../../../20100000.stm/stm0
• <file details> tmc_etf0 -> ../../../20010000.etf/tmc_etf0
• <file details> tmc_etr0 -> ../../../20070000.etr/tmc_etr0
• <file details> tpiu0 -> ../../../20030000.tpiu/tpiu0

How to use the tracer modules

2.17.1