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620 lines
14 KiB
620 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Sound core. This file is composed of two parts. sound_class |
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* which is common to both OSS and ALSA and OSS sound core which |
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* is used OSS or emulation of it. |
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*/ |
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|
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/* |
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* First, the common part. |
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*/ |
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#include <linux/module.h> |
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#include <linux/device.h> |
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#include <linux/err.h> |
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#include <linux/kdev_t.h> |
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#include <linux/major.h> |
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#include <sound/core.h> |
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#ifdef CONFIG_SOUND_OSS_CORE |
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static int __init init_oss_soundcore(void); |
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static void cleanup_oss_soundcore(void); |
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#else |
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static inline int init_oss_soundcore(void) { return 0; } |
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static inline void cleanup_oss_soundcore(void) { } |
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#endif |
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struct class *sound_class; |
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EXPORT_SYMBOL(sound_class); |
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MODULE_DESCRIPTION("Core sound module"); |
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MODULE_AUTHOR("Alan Cox"); |
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MODULE_LICENSE("GPL"); |
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static char *sound_devnode(struct device *dev, umode_t *mode) |
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{ |
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if (MAJOR(dev->devt) == SOUND_MAJOR) |
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return NULL; |
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return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev)); |
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} |
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static int __init init_soundcore(void) |
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{ |
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int rc; |
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rc = init_oss_soundcore(); |
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if (rc) |
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return rc; |
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sound_class = class_create(THIS_MODULE, "sound"); |
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if (IS_ERR(sound_class)) { |
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cleanup_oss_soundcore(); |
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return PTR_ERR(sound_class); |
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} |
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sound_class->devnode = sound_devnode; |
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return 0; |
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} |
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static void __exit cleanup_soundcore(void) |
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{ |
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cleanup_oss_soundcore(); |
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class_destroy(sound_class); |
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} |
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subsys_initcall(init_soundcore); |
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module_exit(cleanup_soundcore); |
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#ifdef CONFIG_SOUND_OSS_CORE |
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/* |
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* OSS sound core handling. Breaks out sound functions to submodules |
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* |
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* Author: Alan Cox <[email protected]> |
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* |
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* Fixes: |
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* |
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* -------------------- |
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* |
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* Top level handler for the sound subsystem. Various devices can |
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* plug into this. The fact they don't all go via OSS doesn't mean |
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* they don't have to implement the OSS API. There is a lot of logic |
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* to keeping much of the OSS weight out of the code in a compatibility |
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* module, but it's up to the driver to rember to load it... |
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* |
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* The code provides a set of functions for registration of devices |
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* by type. This is done rather than providing a single call so that |
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* we can hide any future changes in the internals (eg when we go to |
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* 32bit dev_t) from the modules and their interface. |
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* |
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* Secondly we need to allocate the dsp, dsp16 and audio devices as |
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* one. Thus we misuse the chains a bit to simplify this. |
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* |
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* Thirdly to make it more fun and for 2.3.x and above we do all |
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* of this using fine grained locking. |
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* |
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* FIXME: we have to resolve modules and fine grained load/unload |
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* locking at some point in 2.3.x. |
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*/ |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/types.h> |
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#include <linux/kernel.h> |
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#include <linux/sound.h> |
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#include <linux/kmod.h> |
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#define SOUND_STEP 16 |
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struct sound_unit |
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{ |
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int unit_minor; |
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const struct file_operations *unit_fops; |
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struct sound_unit *next; |
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char name[32]; |
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}; |
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/* |
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* By default, OSS sound_core claims full legacy minor range (0-255) |
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* of SOUND_MAJOR to trap open attempts to any sound minor and |
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* requests modules using custom sound-slot/service-* module aliases. |
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* The only benefit of doing this is allowing use of custom module |
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* aliases instead of the standard char-major-* ones. This behavior |
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* prevents alternative OSS implementation and is scheduled to be |
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* removed. |
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* |
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* CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel |
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* parameter are added to allow distros and developers to try and |
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* switch to alternative implementations without needing to rebuild |
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* the kernel in the meantime. If preclaim_oss is non-zero, the |
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* kernel will behave the same as before. All SOUND_MAJOR minors are |
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* preclaimed and the custom module aliases along with standard chrdev |
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* ones are emitted if a missing device is opened. If preclaim_oss is |
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* zero, sound_core only grabs what's actually in use and for missing |
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* devices only the standard chrdev aliases are requested. |
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* |
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* All these clutters are scheduled to be removed along with |
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* sound-slot/service-* module aliases. |
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*/ |
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#ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM |
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static int preclaim_oss = 1; |
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#else |
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static int preclaim_oss = 0; |
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#endif |
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module_param(preclaim_oss, int, 0444); |
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static int soundcore_open(struct inode *, struct file *); |
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static const struct file_operations soundcore_fops = |
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{ |
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/* We must have an owner or the module locking fails */ |
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.owner = THIS_MODULE, |
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.open = soundcore_open, |
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.llseek = noop_llseek, |
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}; |
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/* |
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* Low level list operator. Scan the ordered list, find a hole and |
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* join into it. Called with the lock asserted |
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*/ |
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static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top) |
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{ |
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int n=low; |
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if (index < 0) { /* first free */ |
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while (*list && (*list)->unit_minor<n) |
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list=&((*list)->next); |
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while(n<top) |
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{ |
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/* Found a hole ? */ |
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if(*list==NULL || (*list)->unit_minor>n) |
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break; |
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list=&((*list)->next); |
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n+=SOUND_STEP; |
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} |
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if(n>=top) |
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return -ENOENT; |
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} else { |
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n = low+(index*16); |
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while (*list) { |
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if ((*list)->unit_minor==n) |
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return -EBUSY; |
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if ((*list)->unit_minor>n) |
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break; |
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list=&((*list)->next); |
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} |
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} |
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/* |
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* Fill it in |
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*/ |
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s->unit_minor=n; |
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s->unit_fops=fops; |
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/* |
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* Link it |
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*/ |
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s->next=*list; |
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*list=s; |
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return n; |
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} |
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/* |
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* Remove a node from the chain. Called with the lock asserted |
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*/ |
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static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit) |
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{ |
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while(*list) |
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{ |
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struct sound_unit *p=*list; |
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if(p->unit_minor==unit) |
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{ |
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*list=p->next; |
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return p; |
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} |
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list=&(p->next); |
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} |
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printk(KERN_ERR "Sound device %d went missing!\n", unit); |
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return NULL; |
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} |
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/* |
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* This lock guards the sound loader list. |
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*/ |
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static DEFINE_SPINLOCK(sound_loader_lock); |
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/* |
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* Allocate the controlling structure and add it to the sound driver |
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* list. Acquires locks as needed |
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*/ |
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static int sound_insert_unit(struct sound_unit **list, const struct file_operations *fops, int index, int low, int top, const char *name, umode_t mode, struct device *dev) |
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{ |
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struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL); |
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int r; |
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if (!s) |
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return -ENOMEM; |
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spin_lock(&sound_loader_lock); |
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retry: |
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r = __sound_insert_unit(s, list, fops, index, low, top); |
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spin_unlock(&sound_loader_lock); |
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if (r < 0) |
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goto fail; |
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else if (r < SOUND_STEP) |
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sprintf(s->name, "sound/%s", name); |
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else |
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sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP); |
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if (!preclaim_oss) { |
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/* |
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* Something else might have grabbed the minor. If |
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* first free slot is requested, rescan with @low set |
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* to the next unit; otherwise, -EBUSY. |
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*/ |
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r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name, |
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&soundcore_fops); |
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if (r < 0) { |
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spin_lock(&sound_loader_lock); |
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__sound_remove_unit(list, s->unit_minor); |
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if (index < 0) { |
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low = s->unit_minor + SOUND_STEP; |
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goto retry; |
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} |
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spin_unlock(&sound_loader_lock); |
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r = -EBUSY; |
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goto fail; |
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} |
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} |
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device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor), |
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NULL, "%s", s->name+6); |
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return s->unit_minor; |
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fail: |
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kfree(s); |
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return r; |
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} |
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/* |
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* Remove a unit. Acquires locks as needed. The drivers MUST have |
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* completed the removal before their file operations become |
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* invalid. |
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*/ |
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static void sound_remove_unit(struct sound_unit **list, int unit) |
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{ |
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struct sound_unit *p; |
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spin_lock(&sound_loader_lock); |
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p = __sound_remove_unit(list, unit); |
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spin_unlock(&sound_loader_lock); |
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if (p) { |
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if (!preclaim_oss) |
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__unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1, |
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p->name); |
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device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor)); |
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kfree(p); |
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} |
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} |
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/* |
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* Allocations |
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* |
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* 0 *16 Mixers |
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* 1 *8 Sequencers |
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* 2 *16 Midi |
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* 3 *16 DSP |
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* 4 *16 SunDSP |
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* 5 *16 DSP16 |
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* 6 -- sndstat (obsolete) |
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* 7 *16 unused |
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* 8 -- alternate sequencer (see above) |
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* 9 *16 raw synthesizer access |
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* 10 *16 unused |
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* 11 *16 unused |
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* 12 *16 unused |
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* 13 *16 unused |
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* 14 *16 unused |
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* 15 *16 unused |
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*/ |
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static struct sound_unit *chains[SOUND_STEP]; |
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/** |
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* register_sound_special_device - register a special sound node |
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* @fops: File operations for the driver |
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* @unit: Unit number to allocate |
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* @dev: device pointer |
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* |
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* Allocate a special sound device by minor number from the sound |
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* subsystem. |
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* |
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* Return: The allocated number is returned on success. On failure, |
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* a negative error code is returned. |
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*/ |
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int register_sound_special_device(const struct file_operations *fops, int unit, |
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struct device *dev) |
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{ |
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const int chain = unit % SOUND_STEP; |
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int max_unit = 256; |
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const char *name; |
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char _name[16]; |
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switch (chain) { |
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case 0: |
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name = "mixer"; |
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break; |
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case 1: |
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name = "sequencer"; |
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if (unit >= SOUND_STEP) |
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goto __unknown; |
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max_unit = unit + 1; |
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break; |
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case 2: |
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name = "midi"; |
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break; |
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case 3: |
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name = "dsp"; |
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break; |
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case 4: |
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name = "audio"; |
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break; |
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case 5: |
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name = "dspW"; |
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break; |
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case 8: |
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name = "sequencer2"; |
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if (unit >= SOUND_STEP) |
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goto __unknown; |
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max_unit = unit + 1; |
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break; |
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case 9: |
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name = "dmmidi"; |
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break; |
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case 10: |
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name = "dmfm"; |
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break; |
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case 12: |
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name = "adsp"; |
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break; |
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case 13: |
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name = "amidi"; |
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break; |
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case 14: |
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name = "admmidi"; |
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break; |
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default: |
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{ |
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__unknown: |
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sprintf(_name, "unknown%d", chain); |
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if (unit >= SOUND_STEP) |
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strcat(_name, "-"); |
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name = _name; |
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} |
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break; |
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} |
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return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit, |
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name, 0600, dev); |
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} |
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EXPORT_SYMBOL(register_sound_special_device); |
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int register_sound_special(const struct file_operations *fops, int unit) |
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{ |
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return register_sound_special_device(fops, unit, NULL); |
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} |
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EXPORT_SYMBOL(register_sound_special); |
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/** |
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* register_sound_mixer - register a mixer device |
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* @fops: File operations for the driver |
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* @dev: Unit number to allocate |
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* |
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* Allocate a mixer device. Unit is the number of the mixer requested. |
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* Pass -1 to request the next free mixer unit. |
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* |
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* Return: On success, the allocated number is returned. On failure, |
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* a negative error code is returned. |
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*/ |
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int register_sound_mixer(const struct file_operations *fops, int dev) |
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{ |
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return sound_insert_unit(&chains[0], fops, dev, 0, 128, |
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"mixer", 0600, NULL); |
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} |
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EXPORT_SYMBOL(register_sound_mixer); |
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/* |
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* DSP's are registered as a triple. Register only one and cheat |
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* in open - see below. |
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*/ |
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/** |
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* register_sound_dsp - register a DSP device |
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* @fops: File operations for the driver |
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* @dev: Unit number to allocate |
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* |
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* Allocate a DSP device. Unit is the number of the DSP requested. |
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* Pass -1 to request the next free DSP unit. |
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* |
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* This function allocates both the audio and dsp device entries together |
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* and will always allocate them as a matching pair - eg dsp3/audio3 |
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* |
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* Return: On success, the allocated number is returned. On failure, |
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* a negative error code is returned. |
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*/ |
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int register_sound_dsp(const struct file_operations *fops, int dev) |
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{ |
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return sound_insert_unit(&chains[3], fops, dev, 3, 131, |
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"dsp", 0600, NULL); |
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} |
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EXPORT_SYMBOL(register_sound_dsp); |
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/** |
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* unregister_sound_special - unregister a special sound device |
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* @unit: unit number to allocate |
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* |
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* Release a sound device that was allocated with |
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* register_sound_special(). The unit passed is the return value from |
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* the register function. |
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*/ |
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void unregister_sound_special(int unit) |
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{ |
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sound_remove_unit(&chains[unit % SOUND_STEP], unit); |
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} |
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EXPORT_SYMBOL(unregister_sound_special); |
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/** |
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* unregister_sound_mixer - unregister a mixer |
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* @unit: unit number to allocate |
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* |
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* Release a sound device that was allocated with register_sound_mixer(). |
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* The unit passed is the return value from the register function. |
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*/ |
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void unregister_sound_mixer(int unit) |
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{ |
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sound_remove_unit(&chains[0], unit); |
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} |
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EXPORT_SYMBOL(unregister_sound_mixer); |
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/** |
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* unregister_sound_dsp - unregister a DSP device |
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* @unit: unit number to allocate |
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* |
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* Release a sound device that was allocated with register_sound_dsp(). |
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* The unit passed is the return value from the register function. |
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* |
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* Both of the allocated units are released together automatically. |
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*/ |
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void unregister_sound_dsp(int unit) |
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{ |
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sound_remove_unit(&chains[3], unit); |
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} |
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EXPORT_SYMBOL(unregister_sound_dsp); |
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static struct sound_unit *__look_for_unit(int chain, int unit) |
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{ |
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struct sound_unit *s; |
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s=chains[chain]; |
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while(s && s->unit_minor <= unit) |
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{ |
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if(s->unit_minor==unit) |
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return s; |
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s=s->next; |
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} |
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return NULL; |
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} |
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static int soundcore_open(struct inode *inode, struct file *file) |
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{ |
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int chain; |
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int unit = iminor(inode); |
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struct sound_unit *s; |
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const struct file_operations *new_fops = NULL; |
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chain=unit&0x0F; |
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if(chain==4 || chain==5) /* dsp/audio/dsp16 */ |
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{ |
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unit&=0xF0; |
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unit|=3; |
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chain=3; |
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} |
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spin_lock(&sound_loader_lock); |
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s = __look_for_unit(chain, unit); |
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if (s) |
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new_fops = fops_get(s->unit_fops); |
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if (preclaim_oss && !new_fops) { |
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spin_unlock(&sound_loader_lock); |
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/* |
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* Please, don't change this order or code. |
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* For ALSA slot means soundcard and OSS emulation code |
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* comes as add-on modules which aren't depend on |
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* ALSA toplevel modules for soundcards, thus we need |
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* load them at first. [Jaroslav Kysela <[email protected]>] |
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*/ |
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request_module("sound-slot-%i", unit>>4); |
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request_module("sound-service-%i-%i", unit>>4, chain); |
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/* |
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* sound-slot/service-* module aliases are scheduled |
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* for removal in favor of the standard char-major-* |
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* module aliases. For the time being, generate both |
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* the legacy and standard module aliases to ease |
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* transition. |
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*/ |
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if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0) |
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request_module("char-major-%d", SOUND_MAJOR); |
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spin_lock(&sound_loader_lock); |
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s = __look_for_unit(chain, unit); |
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if (s) |
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new_fops = fops_get(s->unit_fops); |
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} |
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spin_unlock(&sound_loader_lock); |
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if (new_fops) { |
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/* |
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* We rely upon the fact that we can't be unloaded while the |
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* subdriver is there. |
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*/ |
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int err = 0; |
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replace_fops(file, new_fops); |
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if (file->f_op->open) |
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err = file->f_op->open(inode,file); |
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return err; |
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} |
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return -ENODEV; |
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} |
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MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR); |
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static void cleanup_oss_soundcore(void) |
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{ |
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/* We have nothing to really do here - we know the lists must be |
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empty */ |
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unregister_chrdev(SOUND_MAJOR, "sound"); |
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} |
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static int __init init_oss_soundcore(void) |
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{ |
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if (preclaim_oss && |
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register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) { |
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printk(KERN_ERR "soundcore: sound device already in use.\n"); |
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return -EBUSY; |
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} |
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return 0; |
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} |
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#endif /* CONFIG_SOUND_OSS_CORE */
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