Quelle  device.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Device management routines
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/slab.h>
#include <linux/time.h>
#include <linux/export.h>
#include <linux/errno.h>
#include <sound/core.h>

/**
 * snd_device_new - create an ALSA device component
 * @card: the card instance
 * @type: the device type, SNDRV_DEV_XXX
 * @device_data: the data pointer of this device
 * @ops: the operator table
 *
 * Creates a new device component for the given data pointer.
 * The device will be assigned to the card and managed together
 * by the card.
 *
 * The data pointer plays a role as the identifier, too, so the
 * pointer address must be unique and unchanged.
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
int snd_device_new(struct snd_card *card, enum snd_device_type type,
     void *device_data, const struct snd_device_ops *ops)
{
 struct snd_device *dev;
 struct list_head *p;

 if (snd_BUG_ON(!card || !device_data || !ops))
  return -ENXIO;
 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 if (!dev)
  return -ENOMEM;
 INIT_LIST_HEAD(&dev->list);
 dev->card = card;
 dev->type = type;
 dev->state = SNDRV_DEV_BUILD;
 dev->device_data = device_data;
 dev->ops = ops;

 /* insert the entry in an incrementally sorted list */
 list_for_each_prev(p, &card->devices) {
  struct snd_device *pdev = list_entry(p, struct snd_device, list);
  if ((unsigned int)pdev->type <= (unsigned int)type)
   break;
 }

 list_add(&dev->list, p);
 return 0;
}
EXPORT_SYMBOL(snd_device_new);

static void __snd_device_disconnect(struct snd_device *dev)
{
 if (dev->state == SNDRV_DEV_REGISTERED) {
  if (dev->ops->dev_disconnect &&
      dev->ops->dev_disconnect(dev))
   dev_err(dev->card->dev, "device disconnect failure\n");
  dev->state = SNDRV_DEV_DISCONNECTED;
 }
}

static void __snd_device_free(struct snd_device *dev)
{
 /* unlink */
 list_del(&dev->list);

 __snd_device_disconnect(dev);
 if (dev->ops->dev_free) {
  if (dev->ops->dev_free(dev))
   dev_err(dev->card->dev, "device free failure\n");
 }
 kfree(dev);
}

static struct snd_device *look_for_dev(struct snd_card *card, void *device_data)
{
 struct snd_device *dev;

 list_for_each_entry(dev, &card->devices, list)
  if (dev->device_data == device_data)
   return dev;

 return NULL;
}

/**
 * snd_device_disconnect - disconnect the device
 * @card: the card instance
 * @device_data: the data pointer to disconnect
 *
 * Turns the device into the disconnection state, invoking
 * dev_disconnect callback, if the device was already registered.
 *
 * Usually called from snd_card_disconnect().
 *
 * Return: Zero if successful, or a negative error code on failure or if the
 * device not found.
 */
void snd_device_disconnect(struct snd_card *card, void *device_data)
{
 struct snd_device *dev;

 if (snd_BUG_ON(!card || !device_data))
  return;
 dev = look_for_dev(card, device_data);
 if (dev)
  __snd_device_disconnect(dev);
 else
  dev_dbg(card->dev, "device disconnect %p (from %pS), not found\n",
   device_data, __builtin_return_address(0));
}
EXPORT_SYMBOL_GPL(snd_device_disconnect);

/**
 * snd_device_free - release the device from the card
 * @card: the card instance
 * @device_data: the data pointer to release
 *
 * Removes the device from the list on the card and invokes the
 * callbacks, dev_disconnect and dev_free, corresponding to the state.
 * Then release the device.
 */
void snd_device_free(struct snd_card *card, void *device_data)
{
 struct snd_device *dev;
 
 if (snd_BUG_ON(!card || !device_data))
  return;
 dev = look_for_dev(card, device_data);
 if (dev)
  __snd_device_free(dev);
 else
  dev_dbg(card->dev, "device free %p (from %pS), not found\n",
   device_data, __builtin_return_address(0));
}
EXPORT_SYMBOL(snd_device_free);

static int __snd_device_register(struct snd_device *dev)
{
 if (dev->state == SNDRV_DEV_BUILD) {
  if (dev->ops->dev_register) {
   int err = dev->ops->dev_register(dev);
   if (err < 0)
    return err;
  }
  dev->state = SNDRV_DEV_REGISTERED;
 }
 return 0;
}

/**
 * snd_device_register - register the device
 * @card: the card instance
 * @device_data: the data pointer to register
 *
 * Registers the device which was already created via
 * snd_device_new().  Usually this is called from snd_card_register(),
 * but it can be called later if any new devices are created after
 * invocation of snd_card_register().
 *
 * Return: Zero if successful, or a negative error code on failure or if the
 * device not found.
 */
int snd_device_register(struct snd_card *card, void *device_data)
{
 struct snd_device *dev;

 if (snd_BUG_ON(!card || !device_data))
  return -ENXIO;
 dev = look_for_dev(card, device_data);
 if (dev)
  return __snd_device_register(dev);
 snd_BUG();
 return -ENXIO;
}
EXPORT_SYMBOL(snd_device_register);

/*
 * register all the devices on the card.
 * called from init.c
 */
int snd_device_register_all(struct snd_card *card)
{
 struct snd_device *dev;
 int err;
 
 if (snd_BUG_ON(!card))
  return -ENXIO;
 list_for_each_entry(dev, &card->devices, list) {
  err = __snd_device_register(dev);
  if (err < 0)
   return err;
 }
 return 0;
}

/*
 * disconnect all the devices on the card.
 * called from init.c
 */
void snd_device_disconnect_all(struct snd_card *card)
{
 struct snd_device *dev;

 if (snd_BUG_ON(!card))
  return;
 list_for_each_entry_reverse(dev, &card->devices, list)
  __snd_device_disconnect(dev);
}

/*
 * release all the devices on the card.
 * called from init.c
 */
void snd_device_free_all(struct snd_card *card)
{
 struct snd_device *dev, *next;

 if (snd_BUG_ON(!card))
  return;
 list_for_each_entry_safe_reverse(dev, next, &card->devices, list) {
  /* exception: free ctl and lowlevel stuff later */
  if (dev->type == SNDRV_DEV_CONTROL ||
      dev->type == SNDRV_DEV_LOWLEVEL)
   continue;
  __snd_device_free(dev);
 }

 /* free all */
 list_for_each_entry_safe_reverse(dev, next, &card->devices, list)
  __snd_device_free(dev);
}