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.oobj-$(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