[char-misc-next 4/7] watchdog: mei_wdt: add status debugfs entry

Tomas Winkler
2015-12-17T14:51:15Z

Add entry for dumping current watchdog internal state

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
---
drivers/watchdog/mei_wdt.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 84 insertions(+)

diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
index 3c97deb70d90..a3f1c1613c32 100644
--- a/drivers/watchdog/mei_wdt.c
+++ b/drivers/watchdog/mei_wdt.c
@@ -16,6 +16,7 @@
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/watchdog.h>
+#include <linux/debugfs.h>

#include <linux/uuid.h>
#include <linux/mei_cl_bus.h>
@@ -54,6 +55,19 @@ enum mei_wdt_state {
MEI_WDT_STOPPING,
};

+#if IS_ENABLED(CONFIG_DEBUG_FS)
+static const char *mei_wdt_state_str(enum mei_wdt_state state)
+{
+ switch (state) {
+ case MEI_WDT_IDLE: return "IDLE";
+ case MEI_WDT_START: return "START";
+ case MEI_WDT_RUNNING: return "RUNNING";
+ case MEI_WDT_STOPPING: return "STOPPING";
+ default: return "unknown";
+ }
+}
+#endif /* CONFIG_DEBUG_FS */
+
/**
* struct mei_wdt - mei watchdog driver
* @wdd: watchdog device
@@ -62,6 +76,8 @@ enum mei_wdt_state {
* @state: watchdog internal state
* @cldev: mei watchdog client device
* @timeout: watchdog current timeout
+ *
+ * @dbgfs_dir: debugfs dir entry
*/
struct mei_wdt {
struct watchdog_device wdd;
@@ -70,6 +86,10 @@ struct mei_wdt {
struct mei_cl_device *cldev;
enum mei_wdt_state state;
u16 timeout;
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+ struct dentry *dbgfs_dir;
+#endif /* CONFIG_DEBUG_FS */
};

/*
@@ -296,6 +316,66 @@ static void mei_wdt_ops_unref(struct watchdog_device *wdd)
kref_put(&wdt->refcnt, mei_wdt_release);
}

+#if IS_ENABLED(CONFIG_DEBUG_FS)
+
+static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct mei_wdt *wdt = file->private_data;
+ const size_t bufsz = 32;
+ char buf[32];
+ ssize_t pos = 0;
+
+ pos += scnprintf(buf + pos, bufsz - pos, "state: %s\n",
+ mei_wdt_state_str(wdt->state));
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
+}
+
+static const struct file_operations dbgfs_fops_state = {
+ .open = simple_open,
+ .read = mei_dbgfs_read_state,
+ .llseek = generic_file_llseek,
+};
+
+static void dbgfs_deregister(struct mei_wdt *wdt)
+{
+ if (!wdt->dbgfs_dir)
+ return;
+ debugfs_remove_recursive(wdt->dbgfs_dir);
+ wdt->dbgfs_dir = NULL;
+}
+
+static int dbgfs_register(struct mei_wdt *wdt)
+{
+ struct dentry *dir, *f;
+
+ dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
+ if (!dir)
+ return -ENOMEM;
+
+ wdt->dbgfs_dir = dir;
+ f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
+ if (!f)
+ goto err;
+
+ return 0;
+err:
+ dbgfs_deregister(wdt);
+ return -ENODEV;
+}
+
+#else
+
+static inline void dbgfs_deregister(struct mei_wdt *wdt) {}
+
+static inline int dbgfs_register(struct mei_wdt *wdt)
+{
+ return 0;
+}
+#endif /* CONFIG_DEBUG_FS */
+
+
static const struct watchdog_ops wd_ops = {
.owner = THIS_MODULE,
.start = mei_wdt_ops_start,
@@ -348,6 +428,8 @@ static int mei_wdt_probe(struct mei_cl_device *cldev,
if (ret)
goto err_disable;

+ dbgfs_register(wdt);
+
return 0;

err_disable:
@@ -367,6 +449,8 @@ static int mei_wdt_remove(struct mei_cl_device *cldev)

kref_put(&wdt->refcnt, mei_wdt_release);

+ dbgfs_deregister(wdt);
+
mei_cldev_disable(cldev);

return 0;
--
2.4.3