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Date: Tue, 22 Apr 2014 18:25:25 -0700
From: Frank Rowand <frowand.list@...il.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Grant Likely <grant.likely@...aro.org>,
Rob Herring <robh+dt@...nel.org>
CC: Rob Herring <robh+dt@...nel.org>,
Linux Kernel list <linux-kernel@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: [PATCH] sysfs, device-tree: aid for debugging device tree boot problems
Create some infrastructure to aid trouble shooting device tree related
boot issues.
Add a %driver_name file to each device tree node sysfs directory which has had
a driver bound to it. This allows detecting device tree nodes which failed
to be bound to any driver.
Examples of using the %driver_name file (note that /proc/device-tree is a
link to the base of the device tree sysfs tree):
1) To find list of device tree nodes with no driver:
# A few false positives may be reported. For example,
# node_full_path of "." is the board.
#
# output is: node_full_path compatible_string
#
cd /proc/device-tree
for k in `find . -type d`; do
if [[ -f ${k}/compatible && ! -f ${k}/%driver_name ]] ; then
if [[ "`cat ${k}/compatible`" != "simple-bus" ]] ; then
echo `echo ${k} | sed -e 's|./||'` `cat ${k}/compatible`
fi
fi
done | sort
2) To find list of device tree nodes with a bound driver:
# output is: node_full_path driver_name
#
cd /proc/device-tree
for k in `find . -name %driver_name` ; do
echo `echo ${k} | sed -e 's|./||' -e 's|/%driver_name$||'` `cat ${k}`
done | sort
3) To find list of device tree nodes with a bound driver:
# output is: driver_name node_full_path
#
cd /proc/device-tree
for k in `find . -name %driver_name` ; do
echo `cat ${k}` `echo ${k} | sed -e 's|./||' -e 's|/%driver_name$||'`
done | sort
Signed-off-by: Frank Rowand <frank.rowand@...ymobile.com>
---
Documentation/ABI/testing/sysfs-firmware-ofw | 17 +++++++-
drivers/base/dd.c | 5 ++
drivers/of/base.c | 55 +++++++++++++++++++++++++++
include/linux/of.h | 9 ++++
4 files changed, 85 insertions(+), 1 deletion(-)
Index: b/drivers/base/dd.c
===================================================================
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -25,6 +25,7 @@
#include <linux/kthread.h>
#include <linux/wait.h>
#include <linux/async.h>
+#include <linux/of.h>
#include <linux/pm_runtime.h>
#include <linux/pinctrl/devinfo.h>
@@ -194,6 +195,8 @@ static void driver_bound(struct device *
klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
+ of_notify_driver_bound(dev);
+
/*
* Make sure the device is no longer in one of the deferred lists and
* kick off retrying all pending devices
@@ -505,6 +508,8 @@ static void __device_release_driver(stru
pm_runtime_put_sync(dev);
+ of_notify_driver_released(dev);
+
if (dev->bus && dev->bus->remove)
dev->bus->remove(dev);
else if (drv->remove)
Index: b/drivers/of/base.c
===================================================================
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -19,6 +19,7 @@
*/
#include <linux/ctype.h>
#include <linux/cpu.h>
+#include <linux/kallsyms.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_graph.h>
@@ -168,7 +169,61 @@ static void of_node_release(struct kobje
}
#endif /* CONFIG_OF_DYNAMIC */
+static ssize_t driver_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%s\n", dev->driver->name);
+}
+
+static const struct device_attribute of_driver_attr =
+ __ATTR(%driver_name, S_IRUGO, driver_show, NULL);
+
+void of_notify_driver_bound(struct device *dev)
+{
+ int err;
+
+ if (dev->of_node) {
+ dev->of_node->bound_dev = dev;
+ err = sysfs_create_file(&dev->of_node->kobj, &of_driver_attr.attr);
+ }
+
+}
+
+void of_notify_driver_released(struct device *dev)
+{
+ if (dev->of_node) {
+ sysfs_remove_file(&dev->of_node->kobj, &of_driver_attr.attr);
+ dev->of_node->bound_dev = NULL;
+ }
+}
+
+#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
+
+static ssize_t of_node_attr_show(struct kobject *kobj, struct attribute *attr,
+ char *buf)
+{
+ struct device_attribute *dev_attr = to_dev_attr(attr);
+ struct device_node *np = container_of(kobj, struct device_node, kobj);
+ struct device *dev = np->bound_dev;
+
+ ssize_t ret = -EIO;
+
+ if (dev_attr->show)
+ ret = dev_attr->show(dev, dev_attr, buf);
+ if (ret >= (ssize_t)PAGE_SIZE) {
+ print_symbol("dev_attr_show: %s returned bad count\n",
+ (unsigned long)dev_attr->show);
+ }
+ return ret;
+}
+
+
+static const struct sysfs_ops of_node_sysfs_ops = {
+ .show = of_node_attr_show,
+};
+
struct kobj_type of_node_ktype = {
+ .sysfs_ops = &of_node_sysfs_ops,
.release = of_node_release,
};
Index: b/include/linux/of.h
===================================================================
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -60,6 +60,7 @@ struct device_node {
struct kobject kobj;
unsigned long _flags;
void *data;
+ struct device *bound_dev;
#if defined(CONFIG_SPARC)
const char *path_component_name;
unsigned int unique_id;
@@ -347,6 +348,9 @@ const char *of_prop_next_string(struct p
int of_device_is_stdout_path(struct device_node *dn);
+void of_notify_driver_bound(struct device *dev);
+void of_notify_driver_released(struct device *dev);
+
#else /* CONFIG_OF */
static inline const char* of_node_full_name(struct device_node *np)
@@ -571,6 +575,11 @@ static inline const char *of_prop_next_s
#define of_match_ptr(_ptr) NULL
#define of_match_node(_matches, _node) NULL
+
+void of_notify_driver_bound(struct device *dev) { }
+
+void of_notify_driver_released(struct device *dev) { }
+
#endif /* CONFIG_OF */
#if defined(CONFIG_OF) && defined(CONFIG_NUMA)
Index: b/Documentation/ABI/testing/sysfs-firmware-ofw
===================================================================
--- a/Documentation/ABI/testing/sysfs-firmware-ofw
+++ b/Documentation/ABI/testing/sysfs-firmware-ofw
@@ -25,4 +25,19 @@ Description:
directory name is the resolved path component name (node
name plus address). Properties are represented as files
in the directory. The contents of each file is the exact
- binary data from the device tree.
+ binary data from the device tree. Files that are exceptions
+ to this description will be described separately in this file.
+
+What: /sys/firmware/devicetree/.../%driver_name
+Date: April 2014
+KernelVersion: 3.15
+Contact: Frank Rowand <frank.rowand@...ymobile.com>
+Description:
+ This file does not represent a device tree property. The file
+ will exist only if a driver is bound to the device tree node.
+ Reading from this file returns the name of the driver.
+
+ The apparently bizarre choice of prefixing the file name with
+ "%" is to avoid any possible conflict with a valid device tree
+ property name. ePAPR version 1.1 does not allow a property
+ name to contain the character "%".
--
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