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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: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2015-01-30 12:27:43 +01:00
parent 4227de2a7e
commit 6bbc7fed84
2 changed files with 28 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/sound/core.h
View File

@ -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);

31
sound/core/init.c
View File

@ -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