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// SPDX-License-Identifier: GPL-2.0-or-later
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* Information interface for ALSA driver
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* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
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#include <linux/init.h>
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#include <linux/time.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/module.h>
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#include <dkms/sound/core.h>
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#include <dkms/sound/minors.h>
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#include <dkms/sound/info.h>
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#include <linux/utsname.h>
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#include <linux/proc_fs.h>
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#include <linux/mutex.h>
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int snd_info_check_reserved_words(const char *str)
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static char *reserved[] =
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char **xstr = reserved;
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if (!strcmp(*xstr, str))
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if (!strncmp(str, "card", 4))
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static DEFINE_MUTEX(info_mutex);
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struct snd_info_private_data {
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struct snd_info_buffer *rbuffer;
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struct snd_info_buffer *wbuffer;
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struct snd_info_entry *entry;
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void *file_private_data;
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static int snd_info_version_init(void);
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static void snd_info_disconnect(struct snd_info_entry *entry);
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static struct snd_info_entry *snd_proc_root;
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struct snd_info_entry *snd_seq_root;
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EXPORT_SYMBOL(snd_seq_root);
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#ifdef CONFIG_SND_OSSEMUL
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struct snd_info_entry *snd_oss_root;
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static int alloc_info_private(struct snd_info_entry *entry,
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struct snd_info_private_data **ret)
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struct snd_info_private_data *data;
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if (!entry || !entry->p)
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if (!try_module_get(entry->module))
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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module_put(entry->module);
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static bool valid_pos(loff_t pos, size_t count)
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if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
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if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
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* file ops for binary proc files
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static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
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struct snd_info_private_data *data;
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struct snd_info_entry *entry;
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loff_t ret = -EINVAL, size;
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data = file->private_data;
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mutex_lock(&entry->access);
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if (entry->c.ops->llseek) {
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offset = entry->c.ops->llseek(entry,
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data->file_private_data,
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offset += file->f_pos;
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if (size && offset > size)
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file->f_pos = offset;
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mutex_unlock(&entry->access);
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static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
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size_t count, loff_t * offset)
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struct snd_info_private_data *data = file->private_data;
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struct snd_info_entry *entry = data->entry;
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if (!valid_pos(pos, count))
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if (pos >= entry->size)
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size = entry->size - pos;
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size = min(count, size);
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size = entry->c.ops->read(entry, data->file_private_data,
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file, buffer, size, pos);
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if ((ssize_t) size > 0)
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*offset = pos + size;
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static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer,
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size_t count, loff_t * offset)
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struct snd_info_private_data *data = file->private_data;
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struct snd_info_entry *entry = data->entry;
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if (!valid_pos(pos, count))
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size_t maxsize = entry->size - pos;
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count = min(count, maxsize);
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size = entry->c.ops->write(entry, data->file_private_data,
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file, buffer, count, pos);
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*offset = pos + size;
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static __poll_t snd_info_entry_poll(struct file *file, poll_table *wait)
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struct snd_info_private_data *data = file->private_data;
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struct snd_info_entry *entry = data->entry;
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if (entry->c.ops->poll)
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return entry->c.ops->poll(entry,
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data->file_private_data,
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if (entry->c.ops->read)
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mask |= EPOLLIN | EPOLLRDNORM;
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if (entry->c.ops->write)
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mask |= EPOLLOUT | EPOLLWRNORM;
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static long snd_info_entry_ioctl(struct file *file, unsigned int cmd,
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struct snd_info_private_data *data = file->private_data;
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struct snd_info_entry *entry = data->entry;
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if (!entry->c.ops->ioctl)
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return entry->c.ops->ioctl(entry, data->file_private_data,
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static int snd_info_entry_mmap(struct file *file, struct vm_area_struct *vma)
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struct inode *inode = file_inode(file);
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struct snd_info_private_data *data;
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struct snd_info_entry *entry;
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data = file->private_data;
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if (!entry->c.ops->mmap)
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return entry->c.ops->mmap(entry, data->file_private_data,
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static int snd_info_entry_open(struct inode *inode, struct file *file)
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struct snd_info_entry *entry = PDE_DATA(inode);
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struct snd_info_private_data *data;
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mutex_lock(&info_mutex);
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err = alloc_info_private(entry, &data);
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mode = file->f_flags & O_ACCMODE;
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if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
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((mode == O_WRONLY || mode == O_RDWR) && !entry->c.ops->write)) {
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if (entry->c.ops->open) {
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err = entry->c.ops->open(entry, mode, &data->file_private_data);
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file->private_data = data;
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mutex_unlock(&info_mutex);
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module_put(entry->module);
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mutex_unlock(&info_mutex);
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static int snd_info_entry_release(struct inode *inode, struct file *file)
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struct snd_info_private_data *data = file->private_data;
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struct snd_info_entry *entry = data->entry;
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if (entry->c.ops->release)
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entry->c.ops->release(entry, file->f_flags & O_ACCMODE,
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data->file_private_data);
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module_put(entry->module);
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static const struct file_operations snd_info_entry_operations =
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.owner = THIS_MODULE,
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.llseek = snd_info_entry_llseek,
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.read = snd_info_entry_read,
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.write = snd_info_entry_write,
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.poll = snd_info_entry_poll,
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.unlocked_ioctl = snd_info_entry_ioctl,
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.mmap = snd_info_entry_mmap,
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.open = snd_info_entry_open,
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.release = snd_info_entry_release,
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* file ops for text proc files
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static ssize_t snd_info_text_entry_write(struct file *file,
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const char __user *buffer,
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size_t count, loff_t *offset)
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struct seq_file *m = file->private_data;
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struct snd_info_private_data *data = m->private;
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struct snd_info_entry *entry = data->entry;
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struct snd_info_buffer *buf;
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if (!entry->c.text.write)
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if (!valid_pos(pos, count))
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/* don't handle too large text inputs */
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if (next > 16 * 1024)
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mutex_lock(&entry->access);
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data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
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if (next > buf->len) {
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char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
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buf->len = PAGE_ALIGN(next);
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if (copy_from_user(buf->buffer + pos, buffer, count)) {
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mutex_unlock(&entry->access);
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static int snd_info_seq_show(struct seq_file *seq, void *p)
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struct snd_info_private_data *data = seq->private;
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struct snd_info_entry *entry = data->entry;
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if (!entry->c.text.read) {
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data->rbuffer->buffer = (char *)seq; /* XXX hack! */
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entry->c.text.read(entry, data->rbuffer);
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static int snd_info_text_entry_open(struct inode *inode, struct file *file)
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struct snd_info_entry *entry = PDE_DATA(inode);
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struct snd_info_private_data *data;
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mutex_lock(&info_mutex);
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err = alloc_info_private(entry, &data);
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data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
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if (!data->rbuffer) {
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err = single_open_size(file, snd_info_seq_show, data,
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err = single_open(file, snd_info_seq_show, data);
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mutex_unlock(&info_mutex);
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kfree(data->rbuffer);
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module_put(entry->module);
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mutex_unlock(&info_mutex);
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static int snd_info_text_entry_release(struct inode *inode, struct file *file)
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struct seq_file *m = file->private_data;
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struct snd_info_private_data *data = m->private;
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struct snd_info_entry *entry = data->entry;
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if (data->wbuffer && entry->c.text.write)
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entry->c.text.write(entry, data->wbuffer);
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single_release(inode, file);
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kfree(data->rbuffer);
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kvfree(data->wbuffer->buffer);
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kfree(data->wbuffer);
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module_put(entry->module);
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static const struct file_operations snd_info_text_entry_ops =
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.owner = THIS_MODULE,
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.open = snd_info_text_entry_open,
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.release = snd_info_text_entry_release,
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.write = snd_info_text_entry_write,
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static struct snd_info_entry *create_subdir(struct module *mod,
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struct snd_info_entry *entry;
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entry = snd_info_create_module_entry(mod, name, NULL);
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entry->mode = S_IFDIR | 0555;
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if (snd_info_register(entry) < 0) {
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snd_info_free_entry(entry);
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static struct snd_info_entry *
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snd_info_create_entry(const char *name, struct snd_info_entry *parent,
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struct module *module);
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int __init snd_info_init(void)
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snd_proc_root = snd_info_create_entry("asound", NULL, THIS_MODULE);
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snd_proc_root->mode = S_IFDIR | 0555;
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snd_proc_root->p = proc_mkdir("asound", NULL);
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if (!snd_proc_root->p)
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#ifdef CONFIG_SND_OSSEMUL
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snd_oss_root = create_subdir(THIS_MODULE, "oss");
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#if IS_ENABLED(CONFIG_SND_SEQUENCER)
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snd_seq_root = create_subdir(THIS_MODULE, "seq");
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if (snd_info_version_init() < 0 ||
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snd_minor_info_init() < 0 ||
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snd_minor_info_oss_init() < 0 ||
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snd_card_info_init() < 0 ||
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snd_info_minor_register() < 0)
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snd_info_free_entry(snd_proc_root);
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int __exit snd_info_done(void)
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snd_info_free_entry(snd_proc_root);
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static void snd_card_id_read(struct snd_info_entry *entry,
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struct snd_info_buffer *buffer)
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struct snd_card *card = entry->private_data;
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snd_iprintf(buffer, "%s\n", card->id);
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* create a card proc file
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int snd_info_card_create(struct snd_card *card)
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struct snd_info_entry *entry;
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if (snd_BUG_ON(!card))
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sprintf(str, "card%i", card->number);
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entry = create_subdir(card->module, str);
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card->proc_root = entry;
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return snd_card_ro_proc_new(card, "id", card, snd_card_id_read);
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* register the card proc file
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* can be called multiple times for reinitialization
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int snd_info_card_register(struct snd_card *card)
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struct proc_dir_entry *p;
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if (snd_BUG_ON(!card))
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err = snd_info_register(card->proc_root);
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if (!strcmp(card->id, card->proc_root->name))
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if (card->proc_root_link)
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p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
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card->proc_root_link = p;
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* called on card->id change
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void snd_info_card_id_change(struct snd_card *card)
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mutex_lock(&info_mutex);
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if (card->proc_root_link) {
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proc_remove(card->proc_root_link);
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card->proc_root_link = NULL;
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if (strcmp(card->id, card->proc_root->name))
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card->proc_root_link = proc_symlink(card->id,
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card->proc_root->name);
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mutex_unlock(&info_mutex);
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* de-register the card proc file
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void snd_info_card_disconnect(struct snd_card *card)
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mutex_lock(&info_mutex);
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proc_remove(card->proc_root_link);
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card->proc_root_link = NULL;
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snd_info_disconnect(card->proc_root);
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mutex_unlock(&info_mutex);
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* release the card proc file resources
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int snd_info_card_free(struct snd_card *card)
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snd_info_free_entry(card->proc_root);
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card->proc_root = NULL;
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* snd_info_get_line - read one line from the procfs buffer
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* @buffer: the procfs buffer
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* @line: the buffer to store
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* @len: the max. buffer size
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* Reads one line from the buffer and stores the string.
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* Return: Zero if successful, or 1 if error or EOF.
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int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
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if (snd_BUG_ON(!buffer || !buffer->buffer))
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if (len <= 0 || buffer->stop || buffer->error)
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while (!buffer->stop) {
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c = buffer->buffer[buffer->curr++];
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if (buffer->curr >= buffer->size)
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EXPORT_SYMBOL(snd_info_get_line);
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* snd_info_get_str - parse a string token
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* @dest: the buffer to store the string token
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* @src: the original string
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* @len: the max. length of token - 1
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* Parses the original string and copy a token to the given
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* Return: The updated pointer of the original string so that
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* it can be used for the next call.
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const char *snd_info_get_str(char *dest, const char *src, int len)
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while (*src == ' ' || *src == '\t')
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if (*src == '"' || *src == '\'') {
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while (--len > 0 && *src && *src != c) {
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while (--len > 0 && *src && *src != ' ' && *src != '\t') {
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while (*src == ' ' || *src == '\t')
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EXPORT_SYMBOL(snd_info_get_str);
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* snd_info_create_entry - create an info entry
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* @name: the proc file name
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* @parent: the parent directory
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* Creates an info entry with the given file name and initializes as
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* Usually called from other functions such as
677
* snd_info_create_card_entry().
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* Return: The pointer of the new instance, or %NULL on failure.
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static struct snd_info_entry *
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snd_info_create_entry(const char *name, struct snd_info_entry *parent,
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struct module *module)
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struct snd_info_entry *entry;
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entry = kzalloc(sizeof(*entry), GFP_KERNEL);
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entry->name = kstrdup(name, GFP_KERNEL);
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if (entry->name == NULL) {
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entry->mode = S_IFREG | 0444;
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entry->content = SNDRV_INFO_CONTENT_TEXT;
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mutex_init(&entry->access);
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INIT_LIST_HEAD(&entry->children);
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INIT_LIST_HEAD(&entry->list);
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entry->parent = parent;
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entry->module = module;
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mutex_lock(&parent->access);
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list_add_tail(&entry->list, &parent->children);
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mutex_unlock(&parent->access);
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* snd_info_create_module_entry - create an info entry for the given module
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* @module: the module pointer
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* @name: the file name
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* @parent: the parent directory
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* Creates a new info entry and assigns it to the given module.
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* Return: The pointer of the new instance, or %NULL on failure.
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struct snd_info_entry *snd_info_create_module_entry(struct module * module,
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struct snd_info_entry *parent)
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parent = snd_proc_root;
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return snd_info_create_entry(name, parent, module);
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EXPORT_SYMBOL(snd_info_create_module_entry);
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* snd_info_create_card_entry - create an info entry for the given card
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* @card: the card instance
732
* @name: the file name
733
* @parent: the parent directory
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* Creates a new info entry and assigns it to the given card.
737
* Return: The pointer of the new instance, or %NULL on failure.
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struct snd_info_entry *snd_info_create_card_entry(struct snd_card *card,
741
struct snd_info_entry * parent)
744
parent = card->proc_root;
745
return snd_info_create_entry(name, parent, card->module);
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EXPORT_SYMBOL(snd_info_create_card_entry);
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static void snd_info_disconnect(struct snd_info_entry *entry)
751
struct snd_info_entry *p;
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list_for_each_entry(p, &entry->children, list)
756
snd_info_disconnect(p);
757
proc_remove(entry->p);
762
* snd_info_free_entry - release the info entry
763
* @entry: the info entry
765
* Releases the info entry.
767
void snd_info_free_entry(struct snd_info_entry * entry)
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struct snd_info_entry *p, *n;
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mutex_lock(&info_mutex);
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snd_info_disconnect(entry);
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mutex_unlock(&info_mutex);
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/* free all children at first */
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list_for_each_entry_safe(p, n, &entry->children, list)
781
snd_info_free_entry(p);
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mutex_lock(&p->access);
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list_del(&entry->list);
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mutex_unlock(&p->access);
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if (entry->private_free)
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entry->private_free(entry);
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EXPORT_SYMBOL(snd_info_free_entry);
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static int __snd_info_register(struct snd_info_entry *entry)
798
struct proc_dir_entry *root, *p = NULL;
800
if (snd_BUG_ON(!entry))
802
root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
803
mutex_lock(&info_mutex);
804
if (entry->p || !root)
806
if (S_ISDIR(entry->mode)) {
807
p = proc_mkdir_mode(entry->name, entry->mode, root);
809
mutex_unlock(&info_mutex);
813
const struct file_operations *ops;
814
if (entry->content == SNDRV_INFO_CONTENT_DATA)
815
ops = &snd_info_entry_operations;
817
ops = &snd_info_text_entry_ops;
818
p = proc_create_data(entry->name, entry->mode, root,
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mutex_unlock(&info_mutex);
824
proc_set_size(p, entry->size);
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mutex_unlock(&info_mutex);
833
* snd_info_register - register the info entry
834
* @entry: the info entry
836
* Registers the proc info entry.
837
* The all children entries are registered recursively.
839
* Return: Zero if successful, or a negative error code on failure.
841
int snd_info_register(struct snd_info_entry *entry)
843
struct snd_info_entry *p;
847
err = __snd_info_register(entry);
852
list_for_each_entry(p, &entry->children, list) {
853
err = snd_info_register(p);
860
EXPORT_SYMBOL(snd_info_register);
863
* snd_card_rw_proc_new - Create a read/write text proc file entry for the card
864
* @card: the card instance
865
* @name: the file name
866
* @private_data: the arbitrary private data
867
* @read: the read callback
868
* @write: the write callback, NULL for read-only
870
* This proc file entry will be registered via snd_card_register() call, and
871
* it will be removed automatically at the card removal, too.
873
int snd_card_rw_proc_new(struct snd_card *card, const char *name,
875
void (*read)(struct snd_info_entry *,
876
struct snd_info_buffer *),
877
void (*write)(struct snd_info_entry *entry,
878
struct snd_info_buffer *buffer))
880
struct snd_info_entry *entry;
882
entry = snd_info_create_card_entry(card, name, card->proc_root);
885
snd_info_set_text_ops(entry, private_data, read);
888
entry->c.text.write = write;
892
EXPORT_SYMBOL_GPL(snd_card_rw_proc_new);
898
static void snd_info_version_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
901
"Advanced Linux Sound Architecture Driver Version k%s.\n",
902
init_utsname()->release);
905
static int __init snd_info_version_init(void)
907
struct snd_info_entry *entry;
909
entry = snd_info_create_module_entry(THIS_MODULE, "version", NULL);
912
entry->c.text.read = snd_info_version_read;
913
return snd_info_register(entry); /* freed in error path */