WSL2-Linux-Kernel/arch/um/drivers/hostaudio_kern.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2002 Steve Schmidtke
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sound.h>
#include <linux/soundcard.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <init.h>
#include <os.h>

struct hostaudio_state {
	int fd;
};

struct hostmixer_state {
	int fd;
};

#define HOSTAUDIO_DEV_DSP "/dev/sound/dsp"
#define HOSTAUDIO_DEV_MIXER "/dev/sound/mixer"

/*
 * Changed either at boot time or module load time.  At boot, this is
 * single-threaded; at module load, multiple modules would each have
 * their own copy of these variables.
 */
static char *dsp = HOSTAUDIO_DEV_DSP;
static char *mixer = HOSTAUDIO_DEV_MIXER;

#define DSP_HELP \
"    This is used to specify the host dsp device to the hostaudio driver.\n" \
"    The default is \"" HOSTAUDIO_DEV_DSP "\".\n\n"

#define MIXER_HELP \
"    This is used to specify the host mixer device to the hostaudio driver.\n"\
"    The default is \"" HOSTAUDIO_DEV_MIXER "\".\n\n"

module_param(dsp, charp, 0644);
MODULE_PARM_DESC(dsp, DSP_HELP);
module_param(mixer, charp, 0644);
MODULE_PARM_DESC(mixer, MIXER_HELP);

#ifndef MODULE
static int set_dsp(char *name, int *add)
{
	dsp = name;
	return 0;
}

__uml_setup("dsp=", set_dsp, "dsp=<dsp device>\n" DSP_HELP);

static int set_mixer(char *name, int *add)
{
	mixer = name;
	return 0;
}

__uml_setup("mixer=", set_mixer, "mixer=<mixer device>\n" MIXER_HELP);
#endif

static DEFINE_MUTEX(hostaudio_mutex);

/* /dev/dsp file operations */

static ssize_t hostaudio_read(struct file *file, char __user *buffer,
			      size_t count, loff_t *ppos)
{
	struct hostaudio_state *state = file->private_data;
	void *kbuf;
	int err;

#ifdef DEBUG
	printk(KERN_DEBUG "hostaudio: read called, count = %d\n", count);
#endif

	kbuf = kmalloc(count, GFP_KERNEL);
	if (kbuf == NULL)
		return -ENOMEM;

	err = os_read_file(state->fd, kbuf, count);
	if (err < 0)
		goto out;

	if (copy_to_user(buffer, kbuf, err))
		err = -EFAULT;

out:
	kfree(kbuf);
	return err;
}

static ssize_t hostaudio_write(struct file *file, const char __user *buffer,
			       size_t count, loff_t *ppos)
{
	struct hostaudio_state *state = file->private_data;
	void *kbuf;
	int err;

#ifdef DEBUG
	printk(KERN_DEBUG "hostaudio: write called, count = %d\n", count);
#endif

	kbuf = memdup_user(buffer, count);
	if (IS_ERR(kbuf))
		return PTR_ERR(kbuf);

	err = os_write_file(state->fd, kbuf, count);
	if (err < 0)
		goto out;
	*ppos += err;

 out:
	kfree(kbuf);
	return err;
}

static __poll_t hostaudio_poll(struct file *file,
				struct poll_table_struct *wait)
{
	__poll_t mask = 0;

#ifdef DEBUG
	printk(KERN_DEBUG "hostaudio: poll called (unimplemented)\n");
#endif

	return mask;
}

static long hostaudio_ioctl(struct file *file,
			   unsigned int cmd, unsigned long arg)
{
	struct hostaudio_state *state = file->private_data;
	unsigned long data = 0;
	int err;

#ifdef DEBUG
	printk(KERN_DEBUG "hostaudio: ioctl called, cmd = %u\n", cmd);
#endif
	switch(cmd){
	case SNDCTL_DSP_SPEED:
	case SNDCTL_DSP_STEREO:
	case SNDCTL_DSP_GETBLKSIZE:
	case SNDCTL_DSP_CHANNELS:
	case SNDCTL_DSP_SUBDIVIDE:
	case SNDCTL_DSP_SETFRAGMENT:
		if (get_user(data, (int __user *) arg))
			return -EFAULT;
		break;
	default:
		break;
	}

	err = os_ioctl_generic(state->fd, cmd, (unsigned long) &data);

	switch(cmd){
	case SNDCTL_DSP_SPEED:
	case SNDCTL_DSP_STEREO:
	case SNDCTL_DSP_GETBLKSIZE:
	case SNDCTL_DSP_CHANNELS:
	case SNDCTL_DSP_SUBDIVIDE:
	case SNDCTL_DSP_SETFRAGMENT:
		if (put_user(data, (int __user *) arg))
			return -EFAULT;
		break;
	default:
		break;
	}

	return err;
}

static int hostaudio_open(struct inode *inode, struct file *file)
{
	struct hostaudio_state *state;
	int r = 0, w = 0;
	int ret;

#ifdef DEBUG
	kernel_param_lock(THIS_MODULE);
	printk(KERN_DEBUG "hostaudio: open called (host: %s)\n", dsp);
	kernel_param_unlock(THIS_MODULE);
#endif

	state = kmalloc(sizeof(struct hostaudio_state), GFP_KERNEL);
	if (state == NULL)
		return -ENOMEM;

	if (file->f_mode & FMODE_READ)
		r = 1;
	if (file->f_mode & FMODE_WRITE)
		w = 1;

	kernel_param_lock(THIS_MODULE);
	mutex_lock(&hostaudio_mutex);
	ret = os_open_file(dsp, of_set_rw(OPENFLAGS(), r, w), 0);
	mutex_unlock(&hostaudio_mutex);
	kernel_param_unlock(THIS_MODULE);

	if (ret < 0) {
		kfree(state);
		return ret;
	}
	state->fd = ret;
	file->private_data = state;
	return 0;
}

static int hostaudio_release(struct inode *inode, struct file *file)
{
	struct hostaudio_state *state = file->private_data;

#ifdef DEBUG
	printk(KERN_DEBUG "hostaudio: release called\n");
#endif
	os_close_file(state->fd);
	kfree(state);

	return 0;
}

/* /dev/mixer file operations */

static long hostmixer_ioctl_mixdev(struct file *file,
				  unsigned int cmd, unsigned long arg)
{
	struct hostmixer_state *state = file->private_data;

#ifdef DEBUG
	printk(KERN_DEBUG "hostmixer: ioctl called\n");
#endif

	return os_ioctl_generic(state->fd, cmd, arg);
}

static int hostmixer_open_mixdev(struct inode *inode, struct file *file)
{
	struct hostmixer_state *state;
	int r = 0, w = 0;
	int ret;

#ifdef DEBUG
	printk(KERN_DEBUG "hostmixer: open called (host: %s)\n", mixer);
#endif

	state = kmalloc(sizeof(struct hostmixer_state), GFP_KERNEL);
	if (state == NULL)
		return -ENOMEM;

	if (file->f_mode & FMODE_READ)
		r = 1;
	if (file->f_mode & FMODE_WRITE)
		w = 1;

	kernel_param_lock(THIS_MODULE);
	mutex_lock(&hostaudio_mutex);
	ret = os_open_file(mixer, of_set_rw(OPENFLAGS(), r, w), 0);
	mutex_unlock(&hostaudio_mutex);
	kernel_param_unlock(THIS_MODULE);

	if (ret < 0) {
		kernel_param_lock(THIS_MODULE);
		printk(KERN_ERR "hostaudio_open_mixdev failed to open '%s', "
		       "err = %d\n", dsp, -ret);
		kernel_param_unlock(THIS_MODULE);
		kfree(state);
		return ret;
	}

	file->private_data = state;
	return 0;
}

static int hostmixer_release(struct inode *inode, struct file *file)
{
	struct hostmixer_state *state = file->private_data;

#ifdef DEBUG
	printk(KERN_DEBUG "hostmixer: release called\n");
#endif

	os_close_file(state->fd);
	kfree(state);

	return 0;
}

/* kernel module operations */

static const struct file_operations hostaudio_fops = {
	.owner          = THIS_MODULE,
	.llseek         = no_llseek,
	.read           = hostaudio_read,
	.write          = hostaudio_write,
	.poll           = hostaudio_poll,
	.unlocked_ioctl	= hostaudio_ioctl,
	.compat_ioctl	= compat_ptr_ioctl,
	.mmap           = NULL,
	.open           = hostaudio_open,
	.release        = hostaudio_release,
};

static const struct file_operations hostmixer_fops = {
	.owner          = THIS_MODULE,
	.llseek         = no_llseek,
	.unlocked_ioctl	= hostmixer_ioctl_mixdev,
	.open           = hostmixer_open_mixdev,
	.release        = hostmixer_release,
};

struct {
	int dev_audio;
	int dev_mixer;
} module_data;

MODULE_AUTHOR("Steve Schmidtke");
MODULE_DESCRIPTION("UML Audio Relay");
MODULE_LICENSE("GPL");

static int __init hostaudio_init_module(void)
{
	kernel_param_lock(THIS_MODULE);
	printk(KERN_INFO "UML Audio Relay (host dsp = %s, host mixer = %s)\n",
	       dsp, mixer);
	kernel_param_unlock(THIS_MODULE);

	module_data.dev_audio = register_sound_dsp(&hostaudio_fops, -1);
	if (module_data.dev_audio < 0) {
		printk(KERN_ERR "hostaudio: couldn't register DSP device!\n");
		return -ENODEV;
	}

	module_data.dev_mixer = register_sound_mixer(&hostmixer_fops, -1);
	if (module_data.dev_mixer < 0) {
		printk(KERN_ERR "hostmixer: couldn't register mixer "
		       "device!\n");
		unregister_sound_dsp(module_data.dev_audio);
		return -ENODEV;
	}

	return 0;
}

static void __exit hostaudio_cleanup_module (void)
{
	unregister_sound_mixer(module_data.dev_mixer);
	unregister_sound_dsp(module_data.dev_audio);
}

module_init(hostaudio_init_module);
module_exit(hostaudio_cleanup_module);