ALSA: hda - Add cache support for COEF read/write

The 16bit COEF read/write is pretty standard for many codecs, and they
can be cached in most cases -- more importantly, they need to be
restored at resume.  For making this easier, add the cache support to
regmap.  If the codec driver wants to cache the COEF access, set
codec->cache_coef flag and issue AC_VERB_GET_PROC_COEF with the coef
index in LSB 8 bits.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/hdaudio.h

@@ -78,6 +78,7 @@ struct hdac_device {
 	struct snd_array vendor_verbs;
 	bool lazy_cache:1;	/* don't wake up for writes */
 	bool caps_overwriting:1; /* caps overwrite being in process */
+	bool cache_coef:1;	/* cache COEF read/write too */
 };
 
 /* device/driver type used for matching */

sound/hda/hdac_regmap.c

@@ -33,10 +33,12 @@
 
 static bool hda_volatile_reg(struct device *dev, unsigned int reg)
 {
+	struct hdac_device *codec = dev_to_hdac_dev(dev);
 	unsigned int verb = get_verb(reg);
 
 	switch (verb) {
 	case AC_VERB_GET_PROC_COEF:
+		return !codec->cache_coef;
 	case AC_VERB_GET_COEF_INDEX:
 	case AC_VERB_GET_PROC_STATE:
 	case AC_VERB_GET_POWER_STATE:
@@ -75,6 +77,8 @@ static bool hda_writeable_reg(struct device *dev, unsigned int reg)
 	case AC_VERB_GET_STREAM_FORMAT:
 	case AC_VERB_GET_AMP_GAIN_MUTE:
 		return true;
+	case AC_VERB_GET_PROC_COEF:
+		return codec->cache_coef;
 	case 0xf00:
 		break;
 	default:
@@ -188,9 +192,47 @@ static int hda_reg_write_stereo_amp(struct hdac_device *codec,
 	return 0;
 }
 
+/* read a pseudo coef register (16bit) */
+static int hda_reg_read_coef(struct hdac_device *codec, unsigned int reg,
+			     unsigned int *val)
+{
+	unsigned int verb;
+	int err;
+
+	if (!codec->cache_coef)
+		return -EINVAL;
+	/* LSB 8bit = coef index */
+	verb = (reg & ~0xfff00) | (AC_VERB_SET_COEF_INDEX << 8);
+	err = snd_hdac_exec_verb(codec, verb, 0, NULL);
+	if (err < 0)
+		return err;
+	verb = (reg & ~0xfffff) | (AC_VERB_GET_COEF_INDEX << 8);
+	return snd_hdac_exec_verb(codec, verb, 0, val);
+}
+
+/* write a pseudo coef register (16bit) */
+static int hda_reg_write_coef(struct hdac_device *codec, unsigned int reg,
+			      unsigned int val)
+{
+	unsigned int verb;
+	int err;
+
+	if (!codec->cache_coef)
+		return -EINVAL;
+	/* LSB 8bit = coef index */
+	verb = (reg & ~0xfff00) | (AC_VERB_SET_COEF_INDEX << 8);
+	err = snd_hdac_exec_verb(codec, verb, 0, NULL);
+	if (err < 0)
+		return err;
+	verb = (reg & ~0xfffff) | (AC_VERB_GET_COEF_INDEX << 8) |
+		(val & 0xffff);
+	return snd_hdac_exec_verb(codec, verb, 0, NULL);
+}
+
 static int hda_reg_read(void *context, unsigned int reg, unsigned int *val)
 {
 	struct hdac_device *codec = context;
+	int verb = get_verb(reg);
 	int err;
 
 	if (!codec_is_running(codec))
@@ -198,11 +240,13 @@ static int hda_reg_read(void *context, unsigned int reg, unsigned int *val)
 	reg |= (codec->addr << 28);
 	if (is_stereo_amp_verb(reg))
 		return hda_reg_read_stereo_amp(codec, reg, val);
+	if (verb == AC_VERB_GET_PROC_COEF)
+		return hda_reg_read_coef(codec, reg, val);
 	err = snd_hdac_exec_verb(codec, reg, 0, val);
 	if (err < 0)
 		return err;
 	/* special handling for asymmetric reads */
-	if (get_verb(reg) == AC_VERB_GET_POWER_STATE) {
+	if (verb == AC_VERB_GET_POWER_STATE) {
 		if (*val & AC_PWRST_ERROR)
 			*val = -1;
 		else /* take only the actual state */
@@ -227,6 +271,9 @@ static int hda_reg_write(void *context, unsigned int reg, unsigned int val)
 		return hda_reg_write_stereo_amp(codec, reg, val);
 
 	verb = get_verb(reg);
+	if (verb == AC_VERB_SET_PROC_COEF)
+		return hda_reg_write_coef(codec, reg, val);
+
 	switch (verb & 0xf00) {
 	case AC_VERB_SET_AMP_GAIN_MUTE:
 		verb = AC_VERB_SET_AMP_GAIN_MUTE;