ALSA: usb-audio: Refactor clock finder helpers

There are lots of open-coded functions to find a clock source,
selector and multiplier.  Now there are both v2 and v3, so six
variants.

This patch refactors the code to use a common helper for the main
loop, and define each validator function for each target.
There is no functional change.

Fixes: 9a2fe9b8 ("ALSA: usb: initial USB Audio Device Class 3.0 support")
Reviewed-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/clock.c

@@ -35,105 +35,84 @@
 #include "clock.h"
 #include "quirks.h"
 
-static struct uac_clock_source_descriptor *
-	snd_usb_find_clock_source(struct usb_host_interface *ctrl_iface,
-				  int clock_id)
+static void *find_uac_clock_desc(struct usb_host_interface *iface, int id,
+				 bool (*validator)(void *, int), u8 type)
 {
-	struct uac_clock_source_descriptor *cs = NULL;
+	void *cs = NULL;
 
-	while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
-					     ctrl_iface->extralen,
-					     cs, UAC2_CLOCK_SOURCE))) {
-		if (cs->bLength >= sizeof(*cs) && cs->bClockID == clock_id)
+	while ((cs = snd_usb_find_csint_desc(iface->extra, iface->extralen,
+					     cs, type))) {
+		if (validator(cs, id))
 			return cs;
 	}
 
 	return NULL;
 }
 
-static struct uac3_clock_source_descriptor *
-	snd_usb_find_clock_source_v3(struct usb_host_interface *ctrl_iface,
-				  int clock_id)
+static bool validate_clock_source_v2(void *p, int id)
 {
-	struct uac3_clock_source_descriptor *cs = NULL;
-
-	while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
-					     ctrl_iface->extralen,
-					     cs, UAC3_CLOCK_SOURCE))) {
-		if (cs->bClockID == clock_id)
-			return cs;
-	}
-
-	return NULL;
+	struct uac_clock_source_descriptor *cs = p;
+	return cs->bLength >= sizeof(*cs) && cs->bClockID == id;
 }
 
-static struct uac_clock_selector_descriptor *
-	snd_usb_find_clock_selector(struct usb_host_interface *ctrl_iface,
-				    int clock_id)
+static bool validate_clock_source_v3(void *p, int id)
 {
-	struct uac_clock_selector_descriptor *cs = NULL;
-
-	while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
-					     ctrl_iface->extralen,
-					     cs, UAC2_CLOCK_SELECTOR))) {
-		if (cs->bLength >= sizeof(*cs) && cs->bClockID == clock_id) {
-			if (cs->bLength < 5 + cs->bNrInPins)
-				return NULL;
-			return cs;
-		}
-	}
-
-	return NULL;
+	struct uac3_clock_source_descriptor *cs = p;
+	return cs->bClockID == id;
 }
 
-static struct uac3_clock_selector_descriptor *
-	snd_usb_find_clock_selector_v3(struct usb_host_interface *ctrl_iface,
-				    int clock_id)
+static bool validate_clock_selector_v2(void *p, int id)
 {
-	struct uac3_clock_selector_descriptor *cs = NULL;
-
-	while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
-					     ctrl_iface->extralen,
-					     cs, UAC3_CLOCK_SELECTOR))) {
-		if (cs->bClockID == clock_id)
-			return cs;
-	}
-
-	return NULL;
+	struct uac_clock_selector_descriptor *cs = p;
+	return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
+		cs->bLength >= 5 + cs->bNrInPins;
 }
 
-static struct uac_clock_multiplier_descriptor *
-	snd_usb_find_clock_multiplier(struct usb_host_interface *ctrl_iface,
-				      int clock_id)
+static bool validate_clock_selector_v3(void *p, int id)
 {
-	struct uac_clock_multiplier_descriptor *cs = NULL;
-
-	while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
-					     ctrl_iface->extralen,
-					     cs, UAC2_CLOCK_MULTIPLIER))) {
-		if (cs->bLength >= sizeof(*cs) && cs->bClockID == clock_id)
-			return cs;
-	}
-
-	return NULL;
+	struct uac3_clock_selector_descriptor *cs = p;
+	return cs->bClockID == id;
 }
 
-static struct uac3_clock_multiplier_descriptor *
-	snd_usb_find_clock_multiplier_v3(struct usb_host_interface *ctrl_iface,
-				      int clock_id)
+static bool validate_clock_multiplier_v2(void *p, int id)
 {
-	struct uac3_clock_multiplier_descriptor *cs = NULL;
+	struct uac_clock_multiplier_descriptor *cs = p;
+	return cs->bLength >= sizeof(*cs) && cs->bClockID == id;
+}
 
-	while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
-					     ctrl_iface->extralen,
-					     cs, UAC3_CLOCK_MULTIPLIER))) {
-		if (cs->bClockID == clock_id)
-			return cs;
-	}
+static bool validate_clock_multiplier_v3(void *p, int id)
+{
+	struct uac3_clock_multiplier_descriptor *cs = p;
+	return cs->bClockID == id;
+}
 
-	return NULL;
+#define DEFINE_FIND_HELPER(name, obj, validator, type)		\
+static obj *name(struct usb_host_interface *iface, int id)	\
+{								\
+	return find_uac_clock_desc(iface, id, validator, type);	\
 }
 
+DEFINE_FIND_HELPER(snd_usb_find_clock_source,
+		   struct uac_clock_source_descriptor,
+		   validate_clock_source_v2, UAC2_CLOCK_SOURCE);
+DEFINE_FIND_HELPER(snd_usb_find_clock_source_v3,
+		   struct uac3_clock_source_descriptor,
+		   validate_clock_source_v3, UAC3_CLOCK_SOURCE);
+
+DEFINE_FIND_HELPER(snd_usb_find_clock_selector,
+		   struct uac_clock_selector_descriptor,
+		   validate_clock_selector_v2, UAC2_CLOCK_SELECTOR);
+DEFINE_FIND_HELPER(snd_usb_find_clock_selector_v3,
+		   struct uac3_clock_selector_descriptor,
+		   validate_clock_selector_v3, UAC3_CLOCK_SELECTOR);
+
+DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier,
+		   struct uac_clock_multiplier_descriptor,
+		   validate_clock_multiplier_v2, UAC2_CLOCK_MULTIPLIER);
+DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier_v3,
+		   struct uac3_clock_multiplier_descriptor,
+		   validate_clock_multiplier_v3, UAC3_CLOCK_MULTIPLIER);
+
 static int uac_clock_selector_get_val(struct snd_usb_audio *chip, int selector_id)
 {
 	unsigned char buf;