power: Add option to log time spent in suspend

Prints the time spent in suspend in the kernel log, and
keeps statistics on the time spent in suspend in
/sys/kernel/debug/suspend_time

Change-Id: Ia6b9ebe4baa0f7f5cd211c6a4f7e813aefd3fa1d
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index a70f6c8..b90fb99 100644 (file)
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -294,3 +294,10 @@ config PM_OPP
 config PM_RUNTIME_CLK
        def_bool y
        depends on PM_RUNTIME && HAVE_CLK
+
+config SUSPEND_TIME
+       bool "Log time spent in suspend"
+       ---help---
+         Prints the time spent in suspend in the kernel log, and
+         keeps statistics on the time spent in suspend in
+         /sys/kernel/debug/suspend_time

diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 493f19d..9b224e1 100644 (file)
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -13,5 +13,6 @@ obj-$(CONFIG_USER_WAKELOCK)   += userwakelock.o
 obj-$(CONFIG_EARLYSUSPEND)     += earlysuspend.o
 obj-$(CONFIG_CONSOLE_EARLYSUSPEND)     += consoleearlysuspend.o
 obj-$(CONFIG_FB_EARLYSUSPEND)  += fbearlysuspend.o
+obj-$(CONFIG_SUSPEND_TIME)     += suspend_time.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)      += poweroff.o

diff --git a/kernel/power/suspend_time.c b/kernel/power/suspend_time.c
new file mode 100644 (file)
index 0000000..d2a65da
--- /dev/null
+++ b/kernel/power/suspend_time.c
@@ -0,0 +1,111 @@
+/*
+ * debugfs file to track time spent in suspend
+ *
+ * Copyright (c) 2011, Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/seq_file.h>
+#include <linux/syscore_ops.h>
+#include <linux/time.h>
+
+static struct timespec suspend_time_before;
+static unsigned int time_in_suspend_bins[32];
+
+#ifdef CONFIG_DEBUG_FS
+static int suspend_time_debug_show(struct seq_file *s, void *data)
+{
+       int bin;
+       seq_printf(s, "time (secs)  count\n");
+       seq_printf(s, "------------------\n");
+       for (bin = 0; bin < 32; bin++) {
+               if (time_in_suspend_bins[bin] == 0)
+                       continue;
+               seq_printf(s, "%4d - %4d %4u\n",
+                       bin ? 1 << (bin - 1) : 0, 1 << bin,
+                               time_in_suspend_bins[bin]);
+       }
+       return 0;
+}
+
+static int suspend_time_debug_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, suspend_time_debug_show, NULL);
+}
+
+static const struct file_operations suspend_time_debug_fops = {
+       .open           = suspend_time_debug_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+
+static int __init suspend_time_debug_init(void)
+{
+       struct dentry *d;
+
+       d = debugfs_create_file("suspend_time", 0755, NULL, NULL,
+               &suspend_time_debug_fops);
+       if (!d) {
+               pr_err("Failed to create suspend_time debug file\n");
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+late_initcall(suspend_time_debug_init);
+#endif
+
+static int suspend_time_syscore_suspend(void)
+{
+       read_persistent_clock(&suspend_time_before);
+
+       return 0;
+}
+
+static void suspend_time_syscore_resume(void)
+{
+       struct timespec after;
+
+       read_persistent_clock(&after);
+
+       after = timespec_sub(after, suspend_time_before);
+
+       time_in_suspend_bins[fls(after.tv_sec)]++;
+
+       pr_info("Suspended for %lu.%03lu seconds\n", after.tv_sec,
+               after.tv_nsec / NSEC_PER_MSEC);
+}
+
+static struct syscore_ops suspend_time_syscore_ops = {
+       .suspend = suspend_time_syscore_suspend,
+       .resume = suspend_time_syscore_resume,
+};
+
+static int suspend_time_syscore_init(void)
+{
+       register_syscore_ops(&suspend_time_syscore_ops);
+
+       return 0;
+}
+
+static void suspend_time_syscore_exit(void)
+{
+       unregister_syscore_ops(&suspend_time_syscore_ops);
+}
+module_init(suspend_time_syscore_init);
+module_exit(suspend_time_syscore_exit);