From: John Jacques <[email protected]>
Add a kernel command line option to force the use of acpi_pm as the
watchdog clocksource. To use it, add the following to the
kernel command line:
ricardo_clocksource_wd=force_acpi_pm_wd
and in dmesg look for:
RICARDO: Force acpi_pm as watchdog
Also, add a debugfs entry to inspect the current clocksource watchdog
and the history watchdoug sources. The file is
/sys/kernel/debug/ricardo_clocksource/watchdog_info
It look like something like:
CURRENT: acpi_pm
HISTORY:
apci-pm
Signed-off-by: Ricardo Neri <[email protected]>
Signed-off-by: John Jacques <[email protected]>
[YL: Original patch from
https://github.com/intel-collab/networking.wireless.transport.rdk.board-support.meta-intel-axxia.git.]
Signed-off-by: Yongxin Liu <[email protected]>
---
kernel/time/clocksource.c | 82 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 80 insertions(+), 2 deletions(-)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 3052b1f1168e..fb89243cb6d6 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -16,7 +16,7 @@
#include <linux/kthread.h>
#include <linux/prandom.h>
#include <linux/cpu.h>
-
+#include <linux/debugfs.h>
#include "tick-internal.h"
#include "timekeeping_internal.h"
@@ -398,6 +398,58 @@ static inline void clocksource_reset_watchdog(void)
}
+#define RICARDO_WD_HISTORY_SIZE 1024
+static bool force_acpi_pm_wd;
+static char ricardo_watchdog_history[RICARDO_WD_HISTORY_SIZE];
+
+static void ricardo_append_wd_select(const char *name)
+{
+ static bool buff_full = false;
+ static unsigned buff_pos = 0;
+ unsigned int len;
+
+ if (buff_full)
+ return;
+
+ if (!name)
+ return;
+
+ if (!buff_pos)
+ memset(ricardo_watchdog_history, '\0', RICARDO_WD_HISTORY_SIZE
* sizeof(char));
+
+ len = strlen(name);
+
+ if ((buff_pos + len) > (RICARDO_WD_HISTORY_SIZE - 6)) {
+ memcpy(ricardo_watchdog_history + buff_pos, "FULL\n", 6);
+ buff_full = true;
+ return;
+ }
+
+ memcpy(ricardo_watchdog_history + buff_pos, name, len);
+ buff_pos += len;
+ memcpy(ricardo_watchdog_history + buff_pos, "\n", 1);
+ buff_pos ++;
+}
+
+static int ricardo_watchdog_name_show(struct seq_file *m, void *data)
+{
+ seq_printf(m, "CURRENT: %s\n", watchdog ? watchdog->name : "none");
+ seq_printf(m, "HISTORY: \n%s\n", ricardo_watchdog_history);
+ return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(ricardo_watchdog_name);
+
+static int __init ricardo_override_cs_watchdog(char *str)
+{
+ if (!strcmp(str, "force_acpi_pm_wd")) {
+ printk(KERN_ERR "RICARDO: Force acpi_pm as watchdog\n");
+ force_acpi_pm_wd = true;
+ }
+ return 1;
+}
+early_param("ricardo_clocksource_wd", ricardo_override_cs_watchdog);
+
static void clocksource_watchdog(struct timer_list *unused)
{
u64 csnow, wdnow, cslast, wdlast, delta;
@@ -642,13 +694,23 @@ static void clocksource_select_watchdog(bool fallback)
if (!watchdog || cs->rating > watchdog->rating)
watchdog = cs;
}
+
/* If we failed to find a fallback restore the old one. */
if (!watchdog)
watchdog = old_wd;
+ /*
+ * If selected watchdog is not old_wd, replace with old one. It
+ * will be NULL if not watchdog has been selected
+ */
+ if (force_acpi_pm_wd && strcmp(watchdog->name, "acpi_pm"))
+ watchdog = old_wd;
+
/* If we changed the watchdog we need to reset cycles. */
- if (watchdog != old_wd)
+ if (watchdog != old_wd) {
clocksource_reset_watchdog();
+ ricardo_append_wd_select(watchdog->name);
+ }
/* Check if the watchdog timer needs to be started. */
clocksource_start_watchdog();
@@ -1077,6 +1139,12 @@ static void clocksource_select_fallback(void)
*/
static int __init clocksource_done_booting(void)
{
+ /*
+ * static variable to ensure debugfs entry is called only once even
+ * if this function is called multiple times (once per SMP core up?)
+ */
+ static bool debugfs_done = false;
+ struct dentry *root;
mutex_lock(&clocksource_mutex);
curr_clocksource = clocksource_default_clock();
finished_booting = 1;
@@ -1086,6 +1154,16 @@ static int __init clocksource_done_booting(void)
__clocksource_watchdog_kthread();
clocksource_select();
mutex_unlock(&clocksource_mutex);
+
+ if (!debugfs_done) {
+ debugfs_done = true;
+ root = debugfs_create_dir("ricardo_clocksource", NULL);
+ if (!root) {
+ printk(KERN_ERR "RICARDO Unable to create debugfs
dir\n");
+ return 0;
+ }
+ debugfs_create_file("watchdog_info", 0444, root, NULL,
&ricardo_watchdog_name_fops);
+ }
return 0;
}
fs_initcall(clocksource_done_booting);
--
2.45.0
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