[ALSA] Add pcm_class attribute to PCM sysfs entry

This patch adds a new attribute, pcm_class, to each PCM sysfs entry.
It's useful to detect what kind of PCM stream is, for example, HAL
can check whether it's a modem or not.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

2 files changed, 68 insertions, 12 deletions

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index ed3b09469560..bf8f412988b8 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -907,6 +907,28 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
         substream->pstr->substream_opened--;
 }
 
+static ssize_t show_pcm_class(struct class_device *class_device, char *buf)
+{
+        struct snd_pcm *pcm;
+        const char *str;
+        static const char *strs[SNDRV_PCM_CLASS_LAST + 1] = {
+                [SNDRV_PCM_CLASS_GENERIC] = "generic",
+                [SNDRV_PCM_CLASS_MULTI] = "multi",
+                [SNDRV_PCM_CLASS_MODEM] = "modem",
+                [SNDRV_PCM_CLASS_DIGITIZER] = "digitizer",
+        };
+
+        if (! (pcm = class_get_devdata(class_device)) ||
+            pcm->dev_class > SNDRV_PCM_CLASS_LAST)
+                str = "none";
+        else
+                str = strs[pcm->dev_class];
+        return snprintf(buf, PAGE_SIZE, "%s\n", str);
+}
+
+static struct class_device_attribute pcm_attrs =
+        __ATTR(pcm_class, S_IRUGO, show_pcm_class, NULL);
+
 static int snd_pcm_dev_register(struct snd_device *device)
 {
         int cidx, err;
@@ -945,6 +967,8 @@ static int snd_pcm_dev_register(struct snd_device *device)
                         mutex_unlock(&register_mutex);
                         return err;
                 }
+                snd_add_device_sysfs_file(devtype, pcm->card, pcm->device,
+                                          &pcm_attrs);
                 for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
                         snd_pcm_timer_init(substream);
         }
diff --git a/sound/core/sound.c b/sound/core/sound.c
index b4430db3fa4c..efa476c5210a 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -268,7 +268,11 @@ int snd_register_device(int type, struct snd_card *card, int dev,
         snd_minors[minor] = preg;
         if (card)
                 device = card->dev;
-        class_device_create(sound_class, NULL, MKDEV(major, minor), device, "%s", name);
+        preg->class_dev = class_device_create(sound_class, NULL,
+                                              MKDEV(major, minor),
+                                              device, "%s", name);
+        if (preg->class_dev)
+                class_set_devdata(preg->class_dev, private_data);
 
         mutex_unlock(&sound_mutex);
         return 0;
@@ -276,6 +280,24 @@ int snd_register_device(int type, struct snd_card *card, int dev,
 
 EXPORT_SYMBOL(snd_register_device);
 
+/* find the matching minor record
+ * return the index of snd_minor, or -1 if not found
+ */
+static int find_snd_minor(int type, struct snd_card *card, int dev)
+{
+        int cardnum, minor;
+        struct snd_minor *mptr;
+
+        cardnum = card ? card->number : -1;
+        for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
+                if ((mptr = snd_minors[minor]) != NULL &&
+                    mptr->type == type &&
+                    mptr->card == cardnum &&
+                    mptr->device == dev)
+                        return minor;
+        return -1;
+}
+
 /**
  * snd_unregister_device - unregister the device on the given card
  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
@@ -289,32 +311,42 @@ EXPORT_SYMBOL(snd_register_device);
  */
 int snd_unregister_device(int type, struct snd_card *card, int dev)
 {
-        int cardnum, minor;
-        struct snd_minor *mptr;
+        int minor;
 
-        cardnum = card ? card->number : -1;
         mutex_lock(&sound_mutex);
-        for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
-                if ((mptr = snd_minors[minor]) != NULL &&
-                    mptr->type == type &&
-                    mptr->card == cardnum &&
-                    mptr->device == dev)
-                        break;
-        if (minor == ARRAY_SIZE(snd_minors)) {
+        minor = find_snd_minor(type, card, dev);
+        if (minor < 0) {
                 mutex_unlock(&sound_mutex);
                 return -EINVAL;
         }
 
         class_device_destroy(sound_class, MKDEV(major, minor));
 
+        kfree(snd_minors[minor]);
         snd_minors[minor] = NULL;
         mutex_unlock(&sound_mutex);
-        kfree(mptr);
         return 0;
 }
 
 EXPORT_SYMBOL(snd_unregister_device);
 
+int snd_add_device_sysfs_file(int type, struct snd_card *card, int dev,
+                              const struct class_device_attribute *attr)
+{
+        int minor, ret = -EINVAL;
+        struct class_device *cdev;
+
+        mutex_lock(&sound_mutex);
+        minor = find_snd_minor(type, card, dev);
+        if (minor >= 0 && (cdev = snd_minors[minor]->class_dev) != NULL)
+                ret = class_device_create_file(cdev, attr);
+        mutex_unlock(&sound_mutex);
+        return ret;
+
+}
+
+EXPORT_SYMBOL(snd_add_device_sysfs_file);
+
 #ifdef CONFIG_PROC_FS
 /*
  *  INFO PART