ALSA: hda - Add power on/off counter

Added the power on/off counter and expose via sysfs files.
The sysfs files, power_on_acct and power_off_acct, are created under
each codec hwdep sysfs directory (e.g. /sys/class/sound/hwC0D0).
The files show the msec length of the codec power-on and power-off,
respectively.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index cbf199a..b16678c 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -812,6 +812,9 @@
 	unsigned int power_transition :1; /* power-state in transition */
 	int power_count;	/* current (global) power refcount */
 	struct delayed_work power_work; /* delayed task for powerdown */
+	unsigned long power_on_acct;
+	unsigned long power_off_acct;
+	unsigned long power_jiffies;
 #endif
 
 	/* codec-specific additional proc output */
@@ -936,6 +939,7 @@
 void snd_hda_power_up(struct hda_codec *codec);
 void snd_hda_power_down(struct hda_codec *codec);
 #define snd_hda_codec_needs_resume(codec) codec->power_count
+void snd_hda_update_power_acct(struct hda_codec *codec);
 #else
 static inline void snd_hda_power_up(struct hda_codec *codec) {}
 static inline void snd_hda_power_down(struct hda_codec *codec) {}