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coresight: Expose device connections via sysfs

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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

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 in each device to hold the links.]
Co-developed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200518180242.7916-5-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Suzuki K Poulose 2020-05-18 12:02:23 -06:00 committed by Greg Kroah-Hartman
parent 8096152588
commit 8a7365c2d4
4 changed files with 121 additions and 12 deletions
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5
drivers/hwtracing/coresight/coresight-priv.h
View File

@ -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);

80
drivers/hwtracing/coresight/coresight-sysfs.c
View File

@ -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;
}

46
drivers/hwtracing/coresight/coresight.c
View File

@ -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)

2
include/linux/coresight.h
View File

@ -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;
};
/**