ALSA: pcm: Add snd_pcm_rate_range_to_bits()

This helper function can convert a given sample rate range to
SNDRV_PCM_RATE_xxx bits.

Signed-off-by: Mengdong Lin <mengdong.lin@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/pcm.h

@@ -1093,6 +1093,8 @@ unsigned int snd_pcm_rate_to_rate_bit(unsigned int rate);
 unsigned int snd_pcm_rate_bit_to_rate(unsigned int rate_bit);
 unsigned int snd_pcm_rate_mask_intersect(unsigned int rates_a,
 					 unsigned int rates_b);
+unsigned int snd_pcm_rate_range_to_bits(unsigned int rate_min,
+					unsigned int rate_max);
 
 /**
  * snd_pcm_set_runtime_buffer - Set the PCM runtime buffer

sound/core/pcm_misc.c

@@ -565,3 +565,33 @@ unsigned int snd_pcm_rate_mask_intersect(unsigned int rates_a,
 	return rates_a & rates_b;
 }
 EXPORT_SYMBOL_GPL(snd_pcm_rate_mask_intersect);
+
+/**
+ * snd_pcm_rate_range_to_bits - converts rate range to SNDRV_PCM_RATE_xxx bit
+ * @rate_min: the minimum sample rate
+ * @rate_max: the maximum sample rate
+ *
+ * This function has an implicit assumption: the rates in the given range have
+ * only the pre-defined rates like 44100 or 16000.
+ *
+ * Return: The SNDRV_PCM_RATE_xxx flag that corresponds to the given rate range,
+ * or SNDRV_PCM_RATE_KNOT for an unknown range.
+ */
+unsigned int snd_pcm_rate_range_to_bits(unsigned int rate_min,
+	unsigned int rate_max)
+{
+	unsigned int rates = 0;
+	int i;
+
+	for (i = 0; i < snd_pcm_known_rates.count; i++) {
+		if (snd_pcm_known_rates.list[i] >= rate_min
+			&& snd_pcm_known_rates.list[i] <= rate_max)
+			rates |= 1 << i;
+	}
+
+	if (!rates)
+		rates = SNDRV_PCM_RATE_KNOT;
+
+	return rates;
+}
+EXPORT_SYMBOL_GPL(snd_pcm_rate_range_to_bits);