Commit 6bbc7fed authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: Add a helper to add a new attribute group to card 



For assigning sysfs entries for a card device from the driver,
introduce a new helper function, snd_card_add_dev_attr().  In this
way, we can avoid the possible race between the device registration
and the sysfs addition / removal.

The driver can pass a new attribute group to add freely.  This has to
be called before snd_card_register().

Currently, up to two extra groups can be added.  More than that, it'll
return an error.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 4227de2a

include/sound/core.h

+3 −0
Original line number Diff line number Diff line
@@ -132,6 +132,7 @@ struct snd_card { 
	struct completion *release_completion;

	struct device *dev;		/* device assigned to this card */

	struct device card_dev;		/* cardX object for sysfs */

	const struct attribute_group *dev_groups[4]; /* assigned sysfs attr */

	bool registered;		/* card_dev is registered? */



#ifdef CONFIG_PM
@@ -262,6 +263,8 @@ void snd_card_set_id(struct snd_card *card, const char *id); 
int snd_card_register(struct snd_card *card);

int snd_card_info_init(void);

int snd_card_info_done(void);

int snd_card_add_dev_attr(struct snd_card *card,

			  const struct attribute_group *group);

int snd_component_add(struct snd_card *card, const char *component);

int snd_card_file_add(struct snd_card *card, struct file *file);

int snd_card_file_remove(struct snd_card *card, struct file *file);

sound/core/init.c

+25 −6
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ void snd_device_initialize(struct device *dev, struct snd_card *card) 
EXPORT_SYMBOL_GPL(snd_device_initialize);



static int snd_card_do_free(struct snd_card *card);

static const struct attribute_group *card_dev_attr_groups[];

static const struct attribute_group card_dev_attr_group;



static void release_card_device(struct device *dev)

{
@@ -269,7 +269,8 @@ int snd_card_new(struct device *parent, int idx, const char *xid, 
	card->card_dev.parent = parent;

	card->card_dev.class = sound_class;

	card->card_dev.release = release_card_device;

	card->card_dev.groups = card_dev_attr_groups;

	card->card_dev.groups = card->dev_groups;

	card->dev_groups[0] = &card_dev_attr_group;

	err = kobject_set_name(&card->card_dev.kobj, "card%d", idx);

	if (err < 0)

		goto __error;
@@ -700,14 +701,32 @@ static struct attribute *card_dev_attrs[] = { 
	NULL

};



static struct attribute_group card_dev_attr_group = {

static const struct attribute_group card_dev_attr_group = {

	.attrs	= card_dev_attrs,

};



static const struct attribute_group *card_dev_attr_groups[] = {

	&card_dev_attr_group,

	NULL

/**

 * snd_card_add_dev_attr - Append a new sysfs attribute group to card

 * @card: card instance

 * @group: attribute group to append

 */

int snd_card_add_dev_attr(struct snd_card *card,

			  const struct attribute_group *group)

{

	int i;



	/* loop for (arraysize-1) here to keep NULL at the last entry */

	for (i = 0; i < ARRAY_SIZE(card->dev_groups) - 1; i++) {

		if (!card->dev_groups[i]) {

			card->dev_groups[i] = group;

			return 0;

		}

	}



	dev_err(card->dev, "Too many groups assigned\n");

	return -ENOSPC;

};

EXPORT_SYMBOL_GPL(snd_card_add_dev_attr);



/**

 *  snd_card_register - register the soundcard

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