1. 根目录:
2. include
3. sound
4. hwdep.h

#ifndef __SOUND_HWDEP_H
#define __SOUND_HWDEP_H

/*
 *  Hardware dependent layer 
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/asound.h>
#include <linux/poll.h>

struct snd_hwdep;

/* hwdep file ops; all ops can be NULL */
struct snd_hwdep_ops {
	long long (*llseek)(struct snd_hwdep *hw, struct file *file,
			    long long offset, int orig);
	long (*read)(struct snd_hwdep *hw, char __user *buf,
		     long count, loff_t *offset);
	long (*write)(struct snd_hwdep *hw, const char __user *buf,
		      long count, loff_t *offset);
	int (*open)(struct snd_hwdep *hw, struct file * file);
	int (*release)(struct snd_hwdep *hw, struct file * file);
	unsigned int (*poll)(struct snd_hwdep *hw, struct file *file,
			     poll_table *wait);
	int (*ioctl)(struct snd_hwdep *hw, struct file *file,
		     unsigned int cmd, unsigned long arg);
	int (*ioctl_compat)(struct snd_hwdep *hw, struct file *file,
			    unsigned int cmd, unsigned long arg);
	int (*mmap)(struct snd_hwdep *hw, struct file *file,
		    struct vm_area_struct *vma);
	int (*dsp_status)(struct snd_hwdep *hw,
			  struct snd_hwdep_dsp_status *status);
	int (*dsp_load)(struct snd_hwdep *hw,
			struct snd_hwdep_dsp_image *image);
};

struct snd_hwdep {
	struct snd_card *card;
	struct list_head list;
	int device;
	char id[32];
	char name[80];
	int iface;

#ifdef CONFIG_SND_OSSEMUL
	char oss_dev[32];
	int oss_type;
	int ossreg;
#endif

	struct snd_hwdep_ops ops;
	wait_queue_head_t open_wait;
	void *private_data;
	void (*private_free) (struct snd_hwdep *hwdep);

	struct mutex open_mutex;
	int used;			/* reference counter */
	unsigned int dsp_loaded;	/* bit fields of loaded dsp indices */
	unsigned int exclusive:1;	/* exclusive access mode */
};

extern int snd_hwdep_new(struct snd_card *card, char *id, int device,
			 struct snd_hwdep **rhwdep);

#endif /* __SOUND_HWDEP_H */