[PATCH v3] component: add debugfs support

From: Maciej Purski
Date: Fri Nov 24 2017 - 05:36:01 EST


Add 'component' directory to debugfs. Create a new file for each master,
when a master is added. Remove it on a master deletion.

Show a list of devices matched with master and indicate if
master's components were successfully added and if the whole master is
bound.

Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx>
---
Changes in v3:
- get rid of useless check
- change directory name to "device_component"

Changes in v2:
- use seq_printf() instead of seq_puts() when printing headers
- move whole debugfs code to the file beginning in order to avoid
forward declarations or using multiple ifdefs
---
drivers/base/component.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)

diff --git a/drivers/base/component.c b/drivers/base/component.c
index 89b032f..6c8871d 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -17,6 +17,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/debugfs.h>

struct component;

@@ -41,6 +42,7 @@ struct master {
const struct component_master_ops *ops;
struct device *dev;
struct component_match *match;
+ struct dentry *dentry;
};

struct component {
@@ -56,6 +58,82 @@ static DEFINE_MUTEX(component_mutex);
static LIST_HEAD(component_list);
static LIST_HEAD(masters);

+#ifdef CONFIG_DEBUG_FS
+
+static struct dentry *component_debugfs_dir;
+
+static int component_devices_show(struct seq_file *s, void *data)
+{
+ struct master *m = s->private;
+ struct component_match *match = m->match;
+ size_t i;
+
+ mutex_lock(&component_mutex);
+ seq_printf(s, "%-40s %20s\n", "master name", "status");
+ seq_puts(s, "-------------------------------------------------------------\n");
+ seq_printf(s, "%-40s %20s\n\n",
+ dev_name(m->dev), m->bound ? "bound" : "not bound");
+
+ seq_printf(s, "%-40s %20s\n", "device name", "status");
+ seq_puts(s, "-------------------------------------------------------------\n");
+ for (i = 0; i < match->num; i++) {
+ struct device *d = (struct device *)match->compare[i].data;
+
+ seq_printf(s, "%-40s %20s\n", dev_name(d),
+ match->compare[i].component ?
+ "registered" : "not registered");
+ }
+ mutex_unlock(&component_mutex);
+
+ return 0;
+}
+
+static int component_devices_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, component_devices_show, inode->i_private);
+}
+
+static const struct file_operations component_devices_fops = {
+ .open = component_devices_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init component_debug_init(void)
+{
+ component_debugfs_dir = debugfs_create_dir("device_component", NULL);
+
+ return 0;
+}
+
+core_initcall(component_debug_init);
+
+static void component_master_debugfs_add(struct master *m)
+{
+ m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
+ component_debugfs_dir,
+ m, &component_devices_fops);
+}
+
+static void component_master_debugfs_del(struct master *m)
+{
+ debugfs_remove(m->dentry);
+ m->dentry = NULL;
+}
+
+#else
+
+static void component_master_debugfs_add(struct master *m)
+{
+}
+
+static void component_master_debugfs_del(struct master *m)
+{
+}
+
+#endif
+
static struct master *__master_find(struct device *dev,
const struct component_master_ops *ops)
{
@@ -290,6 +368,7 @@ static void free_master(struct master *master)
struct component_match *match = master->match;
int i;

+ component_master_debugfs_del(master);
list_del(&master->node);

if (match) {
@@ -323,6 +402,7 @@ int component_master_add_with_match(struct device *dev,
master->ops = ops;
master->match = match;

+ component_master_debugfs_add(master);
/* Add to the list of available masters. */
mutex_lock(&component_mutex);
list_add(&master->node, &masters);
--
2.7.4