ALSA: usb-mixer: parse descriptors with structs

Introduce a number of new structs for mixer, selector, feature and
processing units and some static inline helpers to access fields which
have dynamic offsets. Use them in mixer.c to parse the descriptors. This
is necessary for the upcoming audio v2 parsers.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 166 insertions, 50 deletions

diff --git a/include/linux/usb/audio.h b/include/linux/usb/audio.h
index cdad728543ae..bc78a83d0f48 100644
--- a/include/linux/usb/audio.h
+++ b/include/linux/usb/audio.h
@@ -181,6 +181,125 @@ struct uac_feature_unit_descriptor_##ch {			\
         __u8  iFeature;                                         \
 } __attribute__ ((packed))
 
+/* 4.3.2.3 Mixer Unit Descriptor */
+struct uac_mixer_unit_descriptor {
+        __u8 bLength;
+        __u8 bDescriptorType;
+        __u8 bDescriptorSubtype;
+        __u8 bUnitID;
+        __u8 bNrInPins;
+        __u8 baSourceID[];
+} __attribute__ ((packed));
+
+static inline __u8 uac_mixer_unit_bNrChannels(struct uac_mixer_unit_descriptor *desc)
+{
+        return desc->baSourceID[desc->bNrInPins];
+}
+
+static inline __u16 uac_mixer_unit_wChannelConfig(struct uac_mixer_unit_descriptor *desc)
+{
+        return (desc->baSourceID[desc->bNrInPins + 2] << 8) |
+                desc->baSourceID[desc->bNrInPins + 1];
+}
+
+static inline __u8 uac_mixer_unit_iChannelNames(struct uac_mixer_unit_descriptor *desc)
+{
+        return desc->baSourceID[desc->bNrInPins + 3];
+}
+
+static inline __u8 *uac_mixer_unit_bmControls(struct uac_mixer_unit_descriptor *desc)
+{
+        return &desc->baSourceID[desc->bNrInPins + 4];
+}
+
+static inline __u8 uac_mixer_unit_iMixer(struct uac_mixer_unit_descriptor *desc)
+{
+        __u8 *raw = (__u8 *) desc;
+        return raw[desc->bLength - 1];
+}
+
+/* 4.3.2.4 Selector Unit Descriptor */
+struct uac_selector_unit_descriptor {
+        __u8 bLength;
+        __u8 bDescriptorType;
+        __u8 bDescriptorSubtype;
+        __u8 bUintID;
+        __u8 bNrInPins;
+        __u8 baSourceID[];
+} __attribute__ ((packed));
+
+static inline __u8 uac_selector_unit_iSelector(struct uac_selector_unit_descriptor *desc)
+{
+        __u8 *raw = (__u8 *) desc;
+        return raw[desc->bLength - 1];
+}
+
+/* 4.3.2.5 Feature Unit Descriptor */
+struct uac_feature_unit_descriptor {
+        __u8 bLength;
+        __u8 bDescriptorType;
+        __u8 bDescriptorSubtype;
+        __u8 bUnitID;
+        __u8 bSourceID;
+        __u8 bControlSize;
+        __u8 bmaControls[0]; /* variable length */
+} __attribute__((packed));
+
+static inline __u8 uac_feature_unit_iFeature(struct uac_feature_unit_descriptor *desc)
+{
+        __u8 *raw = (__u8 *) desc;
+        return raw[desc->bLength - 1];
+}
+
+/* 4.3.2.6 Processing Unit Descriptors */
+struct uac_processing_unit_descriptor {
+        __u8 bLength;
+        __u8 bDescriptorType;
+        __u8 bDescriptorSubtype;
+        __u8 bUnitID;
+        __u16 wProcessType;
+        __u8 bNrInPins;
+        __u8 baSourceID[];
+} __attribute__ ((packed));
+
+static inline __u8 uac_processing_unit_bNrChannels(struct uac_processing_unit_descriptor *desc)
+{
+        return desc->baSourceID[desc->bNrInPins];
+}
+
+static inline __u16 uac_processing_unit_wChannelConfig(struct uac_processing_unit_descriptor *desc)
+{
+        return (desc->baSourceID[desc->bNrInPins + 2] << 8) |
+                desc->baSourceID[desc->bNrInPins + 1];
+}
+
+static inline __u8 uac_processing_unit_iChannelNames(struct uac_processing_unit_descriptor *desc)
+{
+        return desc->baSourceID[desc->bNrInPins + 3];
+}
+
+static inline __u8 uac_processing_unit_bControlSize(struct uac_processing_unit_descriptor *desc)
+{
+        return desc->baSourceID[desc->bNrInPins + 4];
+}
+
+static inline __u8 *uac_processing_unit_bmControls(struct uac_processing_unit_descriptor *desc)
+{
+        return &desc->baSourceID[desc->bNrInPins + 5];
+}
+
+static inline __u8 uac_processing_unit_iProcessing(struct uac_processing_unit_descriptor *desc)
+{
+        __u8 control_size = uac_processing_unit_bControlSize(desc);
+        return desc->baSourceID[desc->bNrInPins + control_size];
+}
+
+static inline __u8 *uac_processing_unit_specific(struct uac_processing_unit_descriptor *desc)
+{
+        __u8 control_size = uac_processing_unit_bControlSize(desc);
+        return &desc->baSourceID[desc->bNrInPins + control_size + 1];
+}
+
 /* 4.5.2 Class-Specific AS Interface Descriptor */
 struct uac_as_header_descriptor_v1 {
         __u8  bLength;                  /* in bytes: 7 */
@@ -315,16 +434,6 @@ struct uac_iso_endpoint_descriptor {
 
 /* 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
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 4e7c2fd9e3b4..994b0385235c 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -860,13 +860,14 @@ static size_t append_ctl_name(struct snd_kcontrol *kctl, const char *str)
         return strlcat(kctl->id.name, str, sizeof(kctl->id.name));
 }
 
-static void build_feature_ctl(struct mixer_build *state, unsigned char *desc,
+static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
                               unsigned int ctl_mask, int control,
                               struct usb_audio_term *iterm, int unitid)
 {
+        struct uac_feature_unit_descriptor *desc = raw_desc;
         unsigned int len = 0;
         int mapped_name = 0;
-        int nameid = desc[desc[0] - 1];
+        int nameid = uac_feature_unit_iFeature(desc);
         struct snd_kcontrol *kctl;
         struct usb_mixer_elem_info *cval;
         const struct usbmix_name_map *map;
@@ -1032,7 +1033,7 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
 
         channels = (ftr->bLength - 7) / csize - 1;
 
-        master_bits = snd_usb_combine_bytes(ftr->controls, csize);
+        master_bits = snd_usb_combine_bytes(ftr->bmaControls, csize);
         /* master configuration quirks */
         switch (state->chip->usb_id) {
         case USB_ID(0x08bb, 0x2702):
@@ -1043,14 +1044,14 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
                 break;
         }
         if (channels > 0)
-                first_ch_bits = snd_usb_combine_bytes(ftr->controls + csize, csize);
+                first_ch_bits = snd_usb_combine_bytes(ftr->bmaControls + 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->controls + csize * (j+1), csize);
+                        unsigned int mask = snd_usb_combine_bytes(ftr->bmaControls + csize * (j+1), csize);
                         if (mask & (1 << i))
                                 ch_bits |= (1 << j);
                 }
@@ -1075,13 +1076,13 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
  * input channel number (zero based) is given in control field instead.
  */
 
-static void build_mixer_unit_ctl(struct mixer_build *state, unsigned char *desc,
+static void build_mixer_unit_ctl(struct mixer_build *state,
+                                 struct uac_mixer_unit_descriptor *desc,
                                  int in_pin, int in_ch, int unitid,
                                  struct usb_audio_term *iterm)
 {
         struct usb_mixer_elem_info *cval;
-        unsigned int input_pins = desc[4];
-        unsigned int num_outs = desc[5 + input_pins];
+        unsigned int num_outs = uac_mixer_unit_bNrChannels(desc);
         unsigned int i, len;
         struct snd_kcontrol *kctl;
         const struct usbmix_name_map *map;
@@ -1099,7 +1100,7 @@ static void build_mixer_unit_ctl(struct mixer_build *state, unsigned char *desc,
         cval->control = in_ch + 1; /* based on 1 */
         cval->val_type = USB_MIXER_S16;
         for (i = 0; i < num_outs; i++) {
-                if (check_matrix_bitmap(desc + 9 + input_pins, in_ch, i, num_outs)) {
+                if (check_matrix_bitmap(uac_mixer_unit_bmControls(desc), in_ch, i, num_outs)) {
                         cval->cmask |= (1 << i);
                         cval->channels++;
                 }
@@ -1132,18 +1133,19 @@ static void build_mixer_unit_ctl(struct mixer_build *state, unsigned char *desc,
 /*
  * parse a mixer unit
  */
-static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, unsigned char *desc)
+static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, void *raw_desc)
 {
+        struct uac_mixer_unit_descriptor *desc = raw_desc;
         struct usb_audio_term iterm;
         int input_pins, num_ins, num_outs;
         int pin, ich, err;
 
-        if (desc[0] < 11 || ! (input_pins = desc[4]) || ! (num_outs = desc[5 + input_pins])) {
+        if (desc->bLength < 11 || ! (input_pins = desc->bNrInPins) || ! (num_outs = uac_mixer_unit_bNrChannels(desc))) {
                 snd_printk(KERN_ERR "invalid MIXER UNIT descriptor %d\n", unitid);
                 return -EINVAL;
         }
         /* no bmControls field (e.g. Maya44) -> ignore */
-        if (desc[0] <= 10 + input_pins) {
+        if (desc->bLength <= 10 + input_pins) {
                 snd_printdd(KERN_INFO "MU %d has no bmControls field\n", unitid);
                 return 0;
         }
@@ -1151,10 +1153,10 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, unsigne
         num_ins = 0;
         ich = 0;
         for (pin = 0; pin < input_pins; pin++) {
-                err = parse_audio_unit(state, desc[5 + pin]);
+                err = parse_audio_unit(state, desc->baSourceID[pin]);
                 if (err < 0)
                         return err;
-                err = check_input_term(state, desc[5 + pin], &iterm);
+                err = check_input_term(state, desc->baSourceID[pin], &iterm);
                 if (err < 0)
                         return err;
                 num_ins += iterm.channels;
@@ -1162,7 +1164,7 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, unsigne
                         int och, ich_has_controls = 0;
 
                         for (och = 0; och < num_outs; ++och) {
-                                if (check_matrix_bitmap(desc + 9 + input_pins,
+                                if (check_matrix_bitmap(uac_mixer_unit_bmControls(desc),
                                                         ich, och, num_outs)) {
                                         ich_has_controls = 1;
                                         break;
@@ -1323,9 +1325,10 @@ static struct procunit_info extunits[] = {
 /*
  * build a processing/extension unit
  */
-static int build_audio_procunit(struct mixer_build *state, int unitid, unsigned char *dsc, struct procunit_info *list, char *name)
+static int build_audio_procunit(struct mixer_build *state, int unitid, void *raw_desc, struct procunit_info *list, char *name)
 {
-        int num_ins = dsc[6];
+        struct uac_processing_unit_descriptor *desc = raw_desc;
+        int num_ins = desc->bNrInPins;
         struct usb_mixer_elem_info *cval;
         struct snd_kcontrol *kctl;
         int i, err, nameid, type, len;
@@ -1340,17 +1343,17 @@ static int build_audio_procunit(struct mixer_build *state, int unitid, unsigned
                 0, NULL, default_value_info
         };
 
-        if (dsc[0] < 13 || dsc[0] < 13 + num_ins || dsc[0] < num_ins + dsc[11 + num_ins]) {
+        if (desc->bLength < 13 || desc->bLength < 13 + num_ins || desc->bLength < num_ins + uac_processing_unit_bControlSize(desc)) {
                 snd_printk(KERN_ERR "invalid %s descriptor (id %d)\n", name, unitid);
                 return -EINVAL;
         }
 
         for (i = 0; i < num_ins; i++) {
-                if ((err = parse_audio_unit(state, dsc[7 + i])) < 0)
+                if ((err = parse_audio_unit(state, desc->baSourceID[i])) < 0)
                         return err;
         }
 
-        type = combine_word(&dsc[4]);
+        type = le16_to_cpu(desc->wProcessType);
         for (info = list; info && info->type; info++)
                 if (info->type == type)
                         break;
@@ -1358,8 +1361,9 @@ static int build_audio_procunit(struct mixer_build *state, int unitid, unsigned
                 info = &default_info;
 
         for (valinfo = info->values; valinfo->control; valinfo++) {
-                /* FIXME: bitmap might be longer than 8bit */
-                if (! (dsc[12 + num_ins] & (1 << (valinfo->control - 1))))
+                __u8 *controls = uac_processing_unit_bmControls(desc);
+
+                if (! (controls[valinfo->control / 8] & (1 << ((valinfo->control % 8) - 1))))
                         continue;
                 map = find_map(state, unitid, valinfo->control);
                 if (check_ignored_ctl(map))
@@ -1377,9 +1381,10 @@ static int build_audio_procunit(struct mixer_build *state, int unitid, unsigned
 
                 /* get min/max values */
                 if (type == USB_PROC_UPDOWN && cval->control == USB_PROC_UPDOWN_MODE_SEL) {
+                        __u8 *control_spec = uac_processing_unit_specific(desc);
                         /* FIXME: hard-coded */
                         cval->min = 1;
-                        cval->max = dsc[15];
+                        cval->max = control_spec[0];
                         cval->res = 1;
                         cval->initialized = 1;
                 } else {
@@ -1409,7 +1414,7 @@ static int build_audio_procunit(struct mixer_build *state, int unitid, unsigned
                 else if (info->name)
                         strlcpy(kctl->id.name, info->name, sizeof(kctl->id.name));
                 else {
-                        nameid = dsc[12 + num_ins + dsc[11 + num_ins]];
+                        nameid = uac_processing_unit_iProcessing(desc);
                         len = 0;
                         if (nameid)
                                 len = snd_usb_copy_string_desc(state, nameid, kctl->id.name, sizeof(kctl->id.name));
@@ -1428,14 +1433,16 @@ static int build_audio_procunit(struct mixer_build *state, int unitid, unsigned
 }
 
 
-static int parse_audio_processing_unit(struct mixer_build *state, int unitid, unsigned char *desc)
+static int parse_audio_processing_unit(struct mixer_build *state, int unitid, void *raw_desc)
 {
-        return build_audio_procunit(state, unitid, desc, procunits, "Processing Unit");
+        return build_audio_procunit(state, unitid, raw_desc, procunits, "Processing Unit");
 }
 
-static int parse_audio_extension_unit(struct mixer_build *state, int unitid, unsigned char *desc)
+static int parse_audio_extension_unit(struct mixer_build *state, int unitid, void *raw_desc)
 {
-        return build_audio_procunit(state, unitid, desc, extunits, "Extension Unit");
+        /* Note that we parse extension units with processing unit descriptors.
+         * That's ok as the layout is the same */
+        return build_audio_procunit(state, unitid, raw_desc, extunits, "Extension Unit");
 }
 
 
@@ -1537,9 +1544,9 @@ static void usb_mixer_selector_elem_free(struct snd_kcontrol *kctl)
 /*
  * parse a selector unit
  */
-static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsigned char *desc)
+static int parse_audio_selector_unit(struct mixer_build *state, int unitid, void *raw_desc)
 {
-        unsigned int num_ins = desc[4];
+        struct uac_selector_unit_descriptor *desc = raw_desc;
         unsigned int i, nameid, len;
         int err;
         struct usb_mixer_elem_info *cval;
@@ -1547,17 +1554,17 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsi
         const struct usbmix_name_map *map;
         char **namelist;
 
-        if (! num_ins || desc[0] < 5 + num_ins) {
+        if (!desc->bNrInPins || desc->bLength < 5 + desc->bNrInPins) {
                 snd_printk(KERN_ERR "invalid SELECTOR UNIT descriptor %d\n", unitid);
                 return -EINVAL;
         }
 
-        for (i = 0; i < num_ins; i++) {
-                if ((err = parse_audio_unit(state, desc[5 + i])) < 0)
+        for (i = 0; i < desc->bNrInPins; i++) {
+                if ((err = parse_audio_unit(state, desc->baSourceID[i])) < 0)
                         return err;
         }
 
-        if (num_ins == 1) /* only one ? nonsense! */
+        if (desc->bNrInPins == 1) /* only one ? nonsense! */
                 return 0;
 
         map = find_map(state, unitid, 0);
@@ -1574,18 +1581,18 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsi
         cval->val_type = USB_MIXER_U8;
         cval->channels = 1;
         cval->min = 1;
-        cval->max = num_ins;
+        cval->max = desc->bNrInPins;
         cval->res = 1;
         cval->initialized = 1;
 
-        namelist = kmalloc(sizeof(char *) * num_ins, GFP_KERNEL);
+        namelist = kmalloc(sizeof(char *) * desc->bNrInPins, GFP_KERNEL);
         if (! namelist) {
                 snd_printk(KERN_ERR "cannot malloc\n");
                 kfree(cval);
                 return -ENOMEM;
         }
 #define MAX_ITEM_NAME_LEN       64
-        for (i = 0; i < num_ins; i++) {
+        for (i = 0; i < desc->bNrInPins; i++) {
                 struct usb_audio_term iterm;
                 len = 0;
                 namelist[i] = kmalloc(MAX_ITEM_NAME_LEN, GFP_KERNEL);
@@ -1599,7 +1606,7 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsi
                 }
                 len = check_mapped_selector_name(state, unitid, i, namelist[i],
                                                  MAX_ITEM_NAME_LEN);
-                if (! len && check_input_term(state, desc[5 + i], &iterm) >= 0)
+                if (! len && check_input_term(state, desc->baSourceID[i], &iterm) >= 0)
                         len = get_term_name(state, &iterm, namelist[i], MAX_ITEM_NAME_LEN, 0);
                 if (! len)
                         sprintf(namelist[i], "Input %d", i);
@@ -1615,7 +1622,7 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsi
         kctl->private_value = (unsigned long)namelist;
         kctl->private_free = usb_mixer_selector_elem_free;
 
-        nameid = desc[desc[0] - 1];
+        nameid = uac_selector_unit_iSelector(desc);
         len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));
         if (len)
                 ;
@@ -1634,7 +1641,7 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, unsi
         }
 
         snd_printdd(KERN_INFO "[%d] SU [%s] items = %d\n",
-                    cval->id, kctl->id.name, num_ins);
+                    cval->id, kctl->id.name, desc->bNrInPins);
         if ((err = add_control_to_empty(state, kctl)) < 0)
                 return err;