linux/sound/core/init.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Initialization routines
 *  Copyright (c) by Jaroslav Kysela <[email protected]>
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/ctype.h>
#include <linux/pm.h>
#include <linux/debugfs.h>
#include <linux/completion.h>
#include <linux/interrupt.h>

#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>

/* monitor files for graceful shutdown (hotplug) */
struct snd_monitor_file { … };

static DEFINE_SPINLOCK(shutdown_lock);
static LIST_HEAD(shutdown_files);

static const struct file_operations snd_shutdown_f_ops;

/* locked for registering/using */
static DECLARE_BITMAP(snd_cards_lock, SNDRV_CARDS);
static struct snd_card *snd_cards[SNDRV_CARDS];

static DEFINE_MUTEX(snd_card_mutex);

static char *slots[SNDRV_CARDS];
module_param_array(…);
MODULE_PARM_DESC(…) …;

/* return non-zero if the given index is reserved for the given
 * module via slots option
 */
static int module_slot_match(struct module *module, int idx)
{ … }

#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
EXPORT_SYMBOL(…);
#endif

static int check_empty_slot(struct module *module, int slot)
{ … }

/* return an empty slot number (>= 0) found in the given bitmask @mask.
 * @mask == -1 == 0xffffffff means: take any free slot up to 32
 * when no slot is available, return the original @mask as is.
 */
static int get_slot_from_bitmask(int mask, int (*check)(struct module *, int),
				 struct module *module)
{ … }

/* the default release callback set in snd_device_alloc() */
static void default_release_alloc(struct device *dev)
{ … }

/**
 * snd_device_alloc - Allocate and initialize struct device for sound devices
 * @dev_p: pointer to store the allocated device
 * @card: card to assign, optional
 *
 * For releasing the allocated device, call put_device().
 */
int snd_device_alloc(struct device **dev_p, struct snd_card *card)
{ … }
EXPORT_SYMBOL_GPL(…);

static int snd_card_init(struct snd_card *card, struct device *parent,
			 int idx, const char *xid, struct module *module,
			 size_t extra_size);
static int snd_card_do_free(struct snd_card *card);
static const struct attribute_group card_dev_attr_group;

static void release_card_device(struct device *dev)
{ … }

/**
 *  snd_card_new - create and initialize a soundcard structure
 *  @parent: the parent device object
 *  @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 *  @xid: card identification (ASCII string)
 *  @module: top level module for locking
 *  @extra_size: allocate this extra size after the main soundcard structure
 *  @card_ret: the pointer to store the created card instance
 *
 *  The function allocates snd_card instance via kzalloc with the given
 *  space for the driver to use freely.  The allocated struct is stored
 *  in the given card_ret pointer.
 *
 *  Return: Zero if successful or a negative error code.
 */
int snd_card_new(struct device *parent, int idx, const char *xid,
		    struct module *module, int extra_size,
		    struct snd_card **card_ret)
{ … }
EXPORT_SYMBOL(…);

static void __snd_card_release(struct device *dev, void *data)
{ … }

/**
 * snd_devm_card_new - managed snd_card object creation
 * @parent: the parent device object
 * @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 * @xid: card identification (ASCII string)
 * @module: top level module for locking
 * @extra_size: allocate this extra size after the main soundcard structure
 * @card_ret: the pointer to store the created card instance
 *
 * This function works like snd_card_new() but manages the allocated resource
 * via devres, i.e. you don't need to free explicitly.
 *
 * When a snd_card object is created with this function and registered via
 * snd_card_register(), the very first devres action to call snd_card_free()
 * is added automatically.  In that way, the resource disconnection is assured
 * at first, then released in the expected order.
 *
 * If an error happens at the probe before snd_card_register() is called and
 * there have been other devres resources, you'd need to free the card manually
 * via snd_card_free() call in the error; otherwise it may lead to UAF due to
 * devres call orders.  You can use snd_card_free_on_error() helper for
 * handling it more easily.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_devm_card_new(struct device *parent, int idx, const char *xid,
		      struct module *module, size_t extra_size,
		      struct snd_card **card_ret)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * snd_card_free_on_error - a small helper for handling devm probe errors
 * @dev: the managed device object
 * @ret: the return code from the probe callback
 *
 * This function handles the explicit snd_card_free() call at the error from
 * the probe callback.  It's just a small helper for simplifying the error
 * handling with the managed devices.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_card_free_on_error(struct device *dev, int ret)
{ … }
EXPORT_SYMBOL_GPL(…);

static int snd_card_init(struct snd_card *card, struct device *parent,
			 int idx, const char *xid, struct module *module,
			 size_t extra_size)
{ … }

/**
 * snd_card_ref - Get the card object from the index
 * @idx: the card index
 *
 * Returns a card object corresponding to the given index or NULL if not found.
 * Release the object via snd_card_unref().
 *
 * Return: a card object or NULL
 */
struct snd_card *snd_card_ref(int idx)
{ … }
EXPORT_SYMBOL_GPL(…);

/* return non-zero if a card is already locked */
int snd_card_locked(int card)
{ … }

static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
{ … }

static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
				   size_t count, loff_t *offset)
{ … }

static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
				    size_t count, loff_t *offset)
{ … }

static int snd_disconnect_release(struct inode *inode, struct file *file)
{ … }

static __poll_t snd_disconnect_poll(struct file * file, poll_table * wait)
{ … }

static long snd_disconnect_ioctl(struct file *file,
				 unsigned int cmd, unsigned long arg)
{ … }

static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
{ … }

static int snd_disconnect_fasync(int fd, struct file *file, int on)
{ … }

static const struct file_operations snd_shutdown_f_ops = …;

/**
 *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
 *  @card: soundcard structure
 *
 *  Disconnects all APIs from the file-operations (user space).
 *
 *  Return: Zero, otherwise a negative error code.
 *
 *  Note: The current implementation replaces all active file->f_op with special
 *        dummy file operations (they do nothing except release).
 */
void snd_card_disconnect(struct snd_card *card)
{ … }
EXPORT_SYMBOL(…);

/**
 * snd_card_disconnect_sync - disconnect card and wait until files get closed
 * @card: card object to disconnect
 *
 * This calls snd_card_disconnect() for disconnecting all belonging components
 * and waits until all pending files get closed.
 * It assures that all accesses from user-space finished so that the driver
 * can release its resources gracefully.
 */
void snd_card_disconnect_sync(struct snd_card *card)
{ … }
EXPORT_SYMBOL_GPL(…);

static int snd_card_do_free(struct snd_card *card)
{ … }

/**
 * snd_card_free_when_closed - Disconnect the card, free it later eventually
 * @card: soundcard structure
 *
 * Unlike snd_card_free(), this function doesn't try to release the card
 * resource immediately, but tries to disconnect at first.  When the card
 * is still in use, the function returns before freeing the resources.
 * The card resources will be freed when the refcount gets to zero.
 *
 * Return: zero if successful, or a negative error code
 */
void snd_card_free_when_closed(struct snd_card *card)
{ … }
EXPORT_SYMBOL(…);

/**
 * snd_card_free - frees given soundcard structure
 * @card: soundcard structure
 *
 * This function releases the soundcard structure and the all assigned
 * devices automatically.  That is, you don't have to release the devices
 * by yourself.
 *
 * This function waits until the all resources are properly released.
 *
 * Return: Zero. Frees all associated devices and frees the control
 * interface associated to given soundcard.
 */
void snd_card_free(struct snd_card *card)
{ … }
EXPORT_SYMBOL(…);

/* check, if the character is in the valid ASCII range */
static inline bool safe_ascii_char(char c)
{ … }

/* retrieve the last word of shortname or longname */
static const char *retrieve_id_from_card_name(const char *name)
{ … }

/* return true if the given id string doesn't conflict any other card ids */
static bool card_id_ok(struct snd_card *card, const char *id)
{ … }

/* copy to card->id only with valid letters from nid */
static void copy_valid_id_string(struct snd_card *card, const char *src,
				 const char *nid)
{ … }

/* Set card->id from the given string
 * If the string conflicts with other ids, add a suffix to make it unique.
 */
static void snd_card_set_id_no_lock(struct snd_card *card, const char *src,
				    const char *nid)
{ … }

/**
 *  snd_card_set_id - set card identification name
 *  @card: soundcard structure
 *  @nid: new identification string
 *
 *  This function sets the card identification and checks for name
 *  collisions.
 */
void snd_card_set_id(struct snd_card *card, const char *nid)
{ … }
EXPORT_SYMBOL(…);

static ssize_t id_show(struct device *dev,
		       struct device_attribute *attr, char *buf)
{ … }

static ssize_t id_store(struct device *dev, struct device_attribute *attr,
			const char *buf, size_t count)
{ … }

static DEVICE_ATTR_RW(id);

static ssize_t number_show(struct device *dev,
			   struct device_attribute *attr, char *buf)
{ … }

static DEVICE_ATTR_RO(number);

static struct attribute *card_dev_attrs[] = …;

static const struct attribute_group card_dev_attr_group = …;

/**
 * snd_card_add_dev_attr - Append a new sysfs attribute group to card
 * @card: card instance
 * @group: attribute group to append
 *
 * Return: zero if successful, or a negative error code
 */
int snd_card_add_dev_attr(struct snd_card *card,
			  const struct attribute_group *group)
{ … }
EXPORT_SYMBOL_GPL(…);

static void trigger_card_free(void *data)
{ … }

/**
 *  snd_card_register - register the soundcard
 *  @card: soundcard structure
 *
 *  This function registers all the devices assigned to the soundcard.
 *  Until calling this, the ALSA control interface is blocked from the
 *  external accesses.  Thus, you should call this function at the end
 *  of the initialization of the card.
 *
 *  Return: Zero otherwise a negative error code if the registration failed.
 */
int snd_card_register(struct snd_card *card)
{ … }
EXPORT_SYMBOL(…);

#ifdef CONFIG_SND_PROC_FS
static void snd_card_info_read(struct snd_info_entry *entry,
			       struct snd_info_buffer *buffer)
{ … }

#ifdef CONFIG_SND_OSSEMUL
void snd_card_info_read_oss(struct snd_info_buffer *buffer)
{ … }

#endif

#ifdef CONFIG_MODULES
static void snd_card_module_info_read(struct snd_info_entry *entry,
				      struct snd_info_buffer *buffer)
{ … }
#endif

int __init snd_card_info_init(void)
{ … }
#endif /* CONFIG_SND_PROC_FS */

/**
 *  snd_component_add - add a component string
 *  @card: soundcard structure
 *  @component: the component id string
 *
 *  This function adds the component id string to the supported list.
 *  The component can be referred from the alsa-lib.
 *
 *  Return: Zero otherwise a negative error code.
 */
  
int snd_component_add(struct snd_card *card, const char *component)
{ … }
EXPORT_SYMBOL(…);

/**
 *  snd_card_file_add - add the file to the file list of the card
 *  @card: soundcard structure
 *  @file: file pointer
 *
 *  This function adds the file to the file linked-list of the card.
 *  This linked-list is used to keep tracking the connection state,
 *  and to avoid the release of busy resources by hotplug.
 *
 *  Return: zero or a negative error code.
 */
int snd_card_file_add(struct snd_card *card, struct file *file)
{ … }
EXPORT_SYMBOL(…);

/**
 *  snd_card_file_remove - remove the file from the file list
 *  @card: soundcard structure
 *  @file: file pointer
 *
 *  This function removes the file formerly added to the card via
 *  snd_card_file_add() function.
 *  If all files are removed and snd_card_free_when_closed() was
 *  called beforehand, it processes the pending release of
 *  resources.
 *
 *  Return: Zero or a negative error code.
 */
int snd_card_file_remove(struct snd_card *card, struct file *file)
{ … }
EXPORT_SYMBOL(…);

#ifdef CONFIG_PM
/**
 * snd_power_ref_and_wait - wait until the card gets powered up
 * @card: soundcard structure
 *
 * Take the power_ref reference count of the given card, and
 * wait until the card gets powered up to SNDRV_CTL_POWER_D0 state.
 * The refcount is down again while sleeping until power-up, hence this
 * function can be used for syncing the floating control ops accesses,
 * typically around calling control ops.
 *
 * The caller needs to pull down the refcount via snd_power_unref() later
 * no matter whether the error is returned from this function or not.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_power_ref_and_wait(struct snd_card *card)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * snd_power_wait - wait until the card gets powered up (old form)
 * @card: soundcard structure
 *
 * Wait until the card gets powered up to SNDRV_CTL_POWER_D0 state.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_power_wait(struct snd_card *card)
{ … }
EXPORT_SYMBOL(…);
#endif /* CONFIG_PM */