ALSA: hda: Copying sync power state helper to core

The current sync_power_state is local to hda code, moving it
core so that other users apart from hda legacy can use it.
The helper function ensures the actual state reaches the target state.

Signed-off-by: Abhijeet Kumar <abhijeet.kumar@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/hda/hdac_device.c

@@ -3,6 +3,7 @@
  */
 
 #include <linux/init.h>
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/module.h>
@@ -1064,3 +1065,37 @@ bool snd_hdac_check_power_state(struct hdac_device *hdac,
 	return (state == target_state);
 }
 EXPORT_SYMBOL_GPL(snd_hdac_check_power_state);
+/**
+ * snd_hdac_sync_power_state - wait until actual power state matches
+ * with the target state
+ *
+ * @hdac: the HDAC device
+ * @nid: NID to send the command
+ * @target_state: target state to check for
+ *
+ * Return power state or PS_ERROR if codec rejects GET verb.
+ */
+unsigned int snd_hdac_sync_power_state(struct hdac_device *codec,
+			hda_nid_t nid, unsigned int power_state)
+{
+	unsigned long end_time = jiffies + msecs_to_jiffies(500);
+	unsigned int state, actual_state, count;
+
+	for (count = 0; count < 500; count++) {
+		state = snd_hdac_codec_read(codec, nid, 0,
+				AC_VERB_GET_POWER_STATE, 0);
+		if (state & AC_PWRST_ERROR) {
+			msleep(20);
+			break;
+		}
+		actual_state = (state >> 4) & 0x0f;
+		if (actual_state == power_state)
+			break;
+		if (time_after_eq(jiffies, end_time))
+			break;
+		/* wait until the codec reachs to the target state */
+		msleep(1);
+	}
+	return state;
+}
+EXPORT_SYMBOL_GPL(snd_hdac_sync_power_state);