Re: [PATCH v4 3/6] coresight: Add generic sysfs link creation functions.

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