ALSA: usbaudio: parse USB descriptors with structs

In preparation of support for v2.0 audio class, use the structs from
linux/usb/audio.h and add some new ones to describe the fields that are
actually parsed by the descriptor decoders.

Also, factor out code from usb_create_streams(). This makes it easier to
adopt the new iteration logic needed for v2.0.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/linux/usb/audio.h

@@ -81,7 +81,7 @@
 
 /* Terminal Control Selectors */
 /* 4.3.2  Class-Specific AC Interface Descriptor */
-struct uac_ac_header_descriptor {
+struct uac_ac_header_descriptor_v1 {
 	__u8  bLength;			/* 8 + n */
 	__u8  bDescriptorType;		/* USB_DT_CS_INTERFACE */
 	__u8  bDescriptorSubtype;	/* UAC_MS_HEADER */
@@ -95,7 +95,7 @@ struct uac_ac_header_descriptor {
 
 /* As above, but more useful for defining your own descriptors: */
 #define DECLARE_UAC_AC_HEADER_DESCRIPTOR(n) 			\
-struct uac_ac_header_descriptor_##n {				\
+struct uac_ac_header_descriptor_v1_##n {			\
 	__u8  bLength;						\
 	__u8  bDescriptorType;					\
 	__u8  bDescriptorSubtype;				\
@@ -131,7 +131,7 @@ struct uac_input_terminal_descriptor {
 #define UAC_INPUT_TERMINAL_PROC_MICROPHONE_ARRAY	0x206
 
 /* 4.3.2.2 Output Terminal Descriptor */
-struct uac_output_terminal_descriptor {
+struct uac_output_terminal_descriptor_v1 {
 	__u8  bLength;			/* in bytes: 9 */
 	__u8  bDescriptorType;		/* CS_INTERFACE descriptor type */
 	__u8  bDescriptorSubtype;	/* OUTPUT_TERMINAL descriptor subtype */
@@ -171,7 +171,7 @@ struct uac_feature_unit_descriptor_##ch {			\
 } __attribute__ ((packed))
 
 /* 4.5.2 Class-Specific AS Interface Descriptor */
-struct uac_as_header_descriptor {
+struct uac_as_header_descriptor_v1 {
 	__u8  bLength;			/* in bytes: 7 */
 	__u8  bDescriptorType;		/* USB_DT_CS_INTERFACE */
 	__u8  bDescriptorSubtype;	/* AS_GENERAL */
@@ -232,6 +232,19 @@ struct uac_format_type_i_discrete_descriptor_##n {		\
 
 #define UAC_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(n)	(8 + (n * 3))
 
+/* Formats - Audio Data Format Type I Codes */
+
+struct uac_format_type_ii_discrete_descriptor {
+	__u8 bLength;
+	__u8 bDescriptorType;
+	__u8 bDescriptorSubtype;
+	__u8 bFormatType;
+	__le16 wMaxBitRate;
+	__le16 wSamplesPerFrame;
+	__u8 bSamFreqType;
+	__u8 tSamFreq[][3];
+} __attribute__((packed));
+
 /* Formats - A.2 Format Type Codes */
 #define UAC_FORMAT_TYPE_UNDEFINED	0x0
 #define UAC_FORMAT_TYPE_I		0x1
@@ -253,6 +266,17 @@ struct uac_iso_endpoint_descriptor {
 #define UAC_EP_CS_ATTR_FILL_MAX		0x80
 
 /* A.10.2 Feature Unit Control Selectors */
+
+struct uac_feature_unit_descriptor {
+	__u8 bLength;
+	__u8 bDescriptorType;
+	__u8 bDescriptorSubtype;
+	__u8 bUnitID;
+	__u8 bSourceID;
+	__u8 bControlSize;
+	__u8 controls[0]; /* variable length */
+} __attribute__((packed));
+
 #define UAC_FU_CONTROL_UNDEFINED	0x00
 #define UAC_MUTE_CONTROL		0x01
 #define UAC_VOLUME_CONTROL		0x02

sound/usb/usbmixer.c

@@ -32,6 +32,8 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/usb.h>
+#include <linux/usb/audio.h>
+
 #include <sound/core.h>
 #include <sound/control.h>
 #include <sound/hwdep.h>
@@ -1086,29 +1088,30 @@ static void build_feature_ctl(struct mixer_build *state, unsigned char *desc,
  *
  * most of controlls are defined here.
  */
-static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsigned char *ftr)
+static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void *_ftr)
 {
 	int channels, i, j;
 	struct usb_audio_term iterm;
 	unsigned int master_bits, first_ch_bits;
 	int err, csize;
+	struct uac_feature_unit_descriptor *ftr = _ftr;
 
-	if (ftr[0] < 7 || ! (csize = ftr[5]) || ftr[0] < 7 + csize) {
+	if (ftr->bLength < 7 || ! (csize = ftr->bControlSize) || ftr->bLength < 7 + csize) {
 		snd_printk(KERN_ERR "usbaudio: unit %u: invalid FEATURE_UNIT descriptor\n", unitid);
 		return -EINVAL;
 	}
 
 	/* parse the source unit */
-	if ((err = parse_audio_unit(state, ftr[4])) < 0)
+	if ((err = parse_audio_unit(state, ftr->bSourceID)) < 0)
 		return err;
 
 	/* determine the input source type and name */
-	if (check_input_term(state, ftr[4], &iterm) < 0)
+	if (check_input_term(state, ftr->bSourceID, &iterm) < 0)
 		return -EINVAL;
 
-	channels = (ftr[0] - 7) / csize - 1;
+	channels = (ftr->bLength - 7) / csize - 1;
 
-	master_bits = snd_usb_combine_bytes(ftr + 6, csize);
+	master_bits = snd_usb_combine_bytes(ftr->controls, csize);
 	/* master configuration quirks */
 	switch (state->chip->usb_id) {
 	case USB_ID(0x08bb, 0x2702):
@@ -1119,21 +1122,21 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsig
 		break;
 	}
 	if (channels > 0)
-		first_ch_bits = snd_usb_combine_bytes(ftr + 6 + csize, csize);
+		first_ch_bits = snd_usb_combine_bytes(ftr->controls + csize, csize);
 	else
 		first_ch_bits = 0;
 	/* check all control types */
 	for (i = 0; i < 10; i++) {
 		unsigned int ch_bits = 0;
 		for (j = 0; j < channels; j++) {
-			unsigned int mask = snd_usb_combine_bytes(ftr + 6 + csize * (j+1), csize);
+			unsigned int mask = snd_usb_combine_bytes(ftr->controls + csize * (j+1), csize);
 			if (mask & (1 << i))
 				ch_bits |= (1 << j);
 		}
 		if (ch_bits & 1) /* the first channel must be set (for ease of programming) */
-			build_feature_ctl(state, ftr, ch_bits, i, &iterm, unitid);
+			build_feature_ctl(state, _ftr, ch_bits, i, &iterm, unitid);
 		if (master_bits & (1 << i))
-			build_feature_ctl(state, ftr, 0, i, &iterm, unitid);
+			build_feature_ctl(state, _ftr, 0, i, &iterm, unitid);
 	}
 
 	return 0;
@@ -1780,7 +1783,7 @@ static int snd_usb_mixer_dev_free(struct snd_device *device)
  */
 static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
 {
-	unsigned char *desc;
+	struct uac_output_terminal_descriptor_v1 *desc;
 	struct mixer_build state;
 	int err;
 	const struct usbmix_ctl_map *map;
@@ -1805,13 +1808,13 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
 
 	desc = NULL;
 	while ((desc = snd_usb_find_csint_desc(hostif->extra, hostif->extralen, desc, OUTPUT_TERMINAL)) != NULL) {
-		if (desc[0] < 9)
+		if (desc->bLength < 9)
 			continue; /* invalid descriptor? */
-		set_bit(desc[3], state.unitbitmap);  /* mark terminal ID as visited */
-		state.oterm.id = desc[3];
-		state.oterm.type = combine_word(&desc[4]);
-		state.oterm.name = desc[8];
-		err = parse_audio_unit(&state, desc[7]);
+		set_bit(desc->bTerminalID, state.unitbitmap);  /* mark terminal ID as visited */
+		state.oterm.id = desc->bTerminalID;
+		state.oterm.type = le16_to_cpu(desc->wTerminalType);
+		state.oterm.name = desc->iTerminal;
+		err = parse_audio_unit(&state, desc->bSourceID);
 		if (err < 0)
 			return err;
 	}