root/sound/core/hwdep.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Hardware dependent layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/major.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/minors.h>
#include <sound/hwdep.h>
#include <sound/info.h>

MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
MODULE_DESCRIPTION("Hardware dependent layer");
MODULE_LICENSE("GPL");

static LIST_HEAD(snd_hwdep_devices);
static DEFINE_MUTEX(register_mutex);

static int snd_hwdep_dev_free(struct snd_device *device);
static int snd_hwdep_dev_register(struct snd_device *device);
static int snd_hwdep_dev_disconnect(struct snd_device *device);


static struct snd_hwdep *snd_hwdep_search(struct snd_card *card, int device)
{
        struct snd_hwdep *hwdep;

        list_for_each_entry(hwdep, &snd_hwdep_devices, list)
                if (hwdep->card == card && hwdep->device == device)
                        return hwdep;
        return NULL;
}

static loff_t snd_hwdep_llseek(struct file * file, loff_t offset, int orig)
{
        struct snd_hwdep *hw = file->private_data;
        if (hw->ops.llseek)
                return hw->ops.llseek(hw, file, offset, orig);
        return -ENXIO;
}

static ssize_t snd_hwdep_read(struct file * file, char __user *buf,
                              size_t count, loff_t *offset)
{
        struct snd_hwdep *hw = file->private_data;
        if (hw->ops.read)
                return hw->ops.read(hw, buf, count, offset);
        return -ENXIO;  
}

static ssize_t snd_hwdep_write(struct file * file, const char __user *buf,
                               size_t count, loff_t *offset)
{
        struct snd_hwdep *hw = file->private_data;
        if (hw->ops.write)
                return hw->ops.write(hw, buf, count, offset);
        return -ENXIO;  
}

static int snd_hwdep_open(struct inode *inode, struct file * file)
{
        int major = imajor(inode);
        struct snd_hwdep *hw;
        int err;
        wait_queue_entry_t wait;

        if (major == snd_major) {
                hw = snd_lookup_minor_data(iminor(inode),
                                           SNDRV_DEVICE_TYPE_HWDEP);
#ifdef CONFIG_SND_OSSEMUL
        } else if (major == SOUND_MAJOR) {
                hw = snd_lookup_oss_minor_data(iminor(inode),
                                               SNDRV_OSS_DEVICE_TYPE_DMFM);
#endif
        } else
                return -ENXIO;
        if (hw == NULL)
                return -ENODEV;

        if (!try_module_get(hw->card->module)) {
                snd_card_unref(hw->card);
                return -EFAULT;
        }

        init_waitqueue_entry(&wait, current);
        add_wait_queue(&hw->open_wait, &wait);
        mutex_lock(&hw->open_mutex);
        while (1) {
                if (hw->exclusive && hw->used > 0) {
                        err = -EBUSY;
                        break;
                }
                if (!hw->ops.open) {
                        err = 0;
                        break;
                }
                err = hw->ops.open(hw, file);
                if (err >= 0)
                        break;
                if (err == -EAGAIN) {
                        if (file->f_flags & O_NONBLOCK) {
                                err = -EBUSY;
                                break;
                        }
                } else
                        break;
                set_current_state(TASK_INTERRUPTIBLE);
                mutex_unlock(&hw->open_mutex);
                schedule();
                mutex_lock(&hw->open_mutex);
                if (hw->card->shutdown) {
                        err = -ENODEV;
                        break;
                }
                if (signal_pending(current)) {
                        err = -ERESTARTSYS;
                        break;
                }
        }
        remove_wait_queue(&hw->open_wait, &wait);
        if (err >= 0) {
                err = snd_card_file_add(hw->card, file);
                if (err >= 0) {
                        file->private_data = hw;
                        hw->used++;
                } else {
                        if (hw->ops.release)
                                hw->ops.release(hw, file);
                }
        }
        mutex_unlock(&hw->open_mutex);
        if (err < 0)
                module_put(hw->card->module);
        snd_card_unref(hw->card);
        return err;
}

static int snd_hwdep_release(struct inode *inode, struct file * file)
{
        int err = 0;
        struct snd_hwdep *hw = file->private_data;
        struct module *mod = hw->card->module;

        scoped_guard(mutex, &hw->open_mutex) {
                if (hw->ops.release)
                        err = hw->ops.release(hw, file);
                if (hw->used > 0)
                        hw->used--;
        }
        wake_up(&hw->open_wait);

        snd_card_file_remove(hw->card, file);
        module_put(mod);
        return err;
}

static __poll_t snd_hwdep_poll(struct file * file, poll_table * wait)
{
        struct snd_hwdep *hw = file->private_data;
        if (hw->ops.poll)
                return hw->ops.poll(hw, file, wait);
        return 0;
}

static int snd_hwdep_info(struct snd_hwdep *hw,
                          struct snd_hwdep_info __user *_info)
{
        struct snd_hwdep_info info;
        
        memset(&info, 0, sizeof(info));
        info.card = hw->card->number;
        strscpy(info.id, hw->id, sizeof(info.id));
        strscpy(info.name, hw->name, sizeof(info.name));
        info.iface = hw->iface;
        if (copy_to_user(_info, &info, sizeof(info)))
                return -EFAULT;
        return 0;
}

static int snd_hwdep_dsp_status(struct snd_hwdep *hw,
                                struct snd_hwdep_dsp_status __user *_info)
{
        struct snd_hwdep_dsp_status info;
        int err;
        
        if (! hw->ops.dsp_status)
                return -ENXIO;
        memset(&info, 0, sizeof(info));
        info.dsp_loaded = hw->dsp_loaded;
        err = hw->ops.dsp_status(hw, &info);
        if (err < 0)
                return err;
        if (copy_to_user(_info, &info, sizeof(info)))
                return -EFAULT;
        return 0;
}

static int snd_hwdep_dsp_load(struct snd_hwdep *hw,
                              struct snd_hwdep_dsp_image *info)
{
        int err;
        
        if (! hw->ops.dsp_load)
                return -ENXIO;
        if (info->index >= 32)
                return -EINVAL;
        /* check whether the dsp was already loaded */
        if (hw->dsp_loaded & (1u << info->index))
                return -EBUSY;
        err = hw->ops.dsp_load(hw, info);
        if (err < 0)
                return err;
        hw->dsp_loaded |= (1u << info->index);
        return 0;
}

static int snd_hwdep_dsp_load_user(struct snd_hwdep *hw,
                                   struct snd_hwdep_dsp_image __user *_info)
{
        struct snd_hwdep_dsp_image info = {};

        if (copy_from_user(&info, _info, sizeof(info)))
                return -EFAULT;
        return snd_hwdep_dsp_load(hw, &info);
}


static long snd_hwdep_ioctl(struct file * file, unsigned int cmd,
                            unsigned long arg)
{
        struct snd_hwdep *hw = file->private_data;
        void __user *argp = (void __user *)arg;
        switch (cmd) {
        case SNDRV_HWDEP_IOCTL_PVERSION:
                return put_user(SNDRV_HWDEP_VERSION, (int __user *)argp);
        case SNDRV_HWDEP_IOCTL_INFO:
                return snd_hwdep_info(hw, argp);
        case SNDRV_HWDEP_IOCTL_DSP_STATUS:
                return snd_hwdep_dsp_status(hw, argp);
        case SNDRV_HWDEP_IOCTL_DSP_LOAD:
                return snd_hwdep_dsp_load_user(hw, argp);
        }
        if (hw->ops.ioctl)
                return hw->ops.ioctl(hw, file, cmd, arg);
        return -ENOTTY;
}

static int snd_hwdep_mmap(struct file * file, struct vm_area_struct * vma)
{
        struct snd_hwdep *hw = file->private_data;
        if (hw->ops.mmap)
                return hw->ops.mmap(hw, file, vma);
        return -ENXIO;
}

static int snd_hwdep_control_ioctl(struct snd_card *card,
                                   struct snd_ctl_file * control,
                                   unsigned int cmd, unsigned long arg)
{
        switch (cmd) {
        case SNDRV_CTL_IOCTL_HWDEP_NEXT_DEVICE:
                {
                        int device;

                        if (get_user(device, (int __user *)arg))
                                return -EFAULT;

                        scoped_guard(mutex, &register_mutex) {
                                if (device < 0)
                                        device = 0;
                                else if (device < SNDRV_MINOR_HWDEPS)
                                        device++;
                                else
                                        device = SNDRV_MINOR_HWDEPS;

                                while (device < SNDRV_MINOR_HWDEPS) {
                                        if (snd_hwdep_search(card, device))
                                                break;
                                        device++;
                                }
                                if (device >= SNDRV_MINOR_HWDEPS)
                                        device = -1;
                        }
                        if (put_user(device, (int __user *)arg))
                                return -EFAULT;
                        return 0;
                }
        case SNDRV_CTL_IOCTL_HWDEP_INFO:
                {
                        struct snd_hwdep_info __user *info = (struct snd_hwdep_info __user *)arg;
                        int device;
                        struct snd_hwdep *hwdep;

                        if (get_user(device, &info->device))
                                return -EFAULT;
                        scoped_guard(mutex, &register_mutex) {
                                hwdep = snd_hwdep_search(card, device);
                                if (!hwdep)
                                        return -ENXIO;
                                return snd_hwdep_info(hwdep, info);
                        }
                        break;
                }
        }
        return -ENOIOCTLCMD;
}

#ifdef CONFIG_COMPAT
#include "hwdep_compat.c"
#else
#define snd_hwdep_ioctl_compat  NULL
#endif

/*

 */

static const struct file_operations snd_hwdep_f_ops =
{
        .owner =        THIS_MODULE,
        .llseek =       snd_hwdep_llseek,
        .read =         snd_hwdep_read,
        .write =        snd_hwdep_write,
        .open =         snd_hwdep_open,
        .release =      snd_hwdep_release,
        .poll =         snd_hwdep_poll,
        .unlocked_ioctl =       snd_hwdep_ioctl,
        .compat_ioctl = snd_hwdep_ioctl_compat,
        .mmap =         snd_hwdep_mmap,
};

static void snd_hwdep_free(struct snd_hwdep *hwdep)
{
        if (!hwdep)
                return;
        if (hwdep->private_free)
                hwdep->private_free(hwdep);
        put_device(hwdep->dev);
        kfree(hwdep);
}

/**
 * snd_hwdep_new - create a new hwdep instance
 * @card: the card instance
 * @id: the id string
 * @device: the device index (zero-based)
 * @rhwdep: the pointer to store the new hwdep instance
 *
 * Creates a new hwdep instance with the given index on the card.
 * The callbacks (hwdep->ops) must be set on the returned instance
 * after this call manually by the caller.
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
int snd_hwdep_new(struct snd_card *card, char *id, int device,
                  struct snd_hwdep **rhwdep)
{
        struct snd_hwdep *hwdep;
        int err;
        static const struct snd_device_ops ops = {
                .dev_free = snd_hwdep_dev_free,
                .dev_register = snd_hwdep_dev_register,
                .dev_disconnect = snd_hwdep_dev_disconnect,
        };

        if (snd_BUG_ON(!card))
                return -ENXIO;
        if (rhwdep)
                *rhwdep = NULL;
        hwdep = kzalloc_obj(*hwdep);
        if (!hwdep)
                return -ENOMEM;

        init_waitqueue_head(&hwdep->open_wait);
        mutex_init(&hwdep->open_mutex);
        hwdep->card = card;
        hwdep->device = device;
        if (id)
                strscpy(hwdep->id, id, sizeof(hwdep->id));

        err = snd_device_alloc(&hwdep->dev, card);
        if (err < 0) {
                snd_hwdep_free(hwdep);
                return err;
        }

        dev_set_name(hwdep->dev, "hwC%iD%i", card->number, device);
#ifdef CONFIG_SND_OSSEMUL
        hwdep->oss_type = -1;
#endif

        err = snd_device_new(card, SNDRV_DEV_HWDEP, hwdep, &ops);
        if (err < 0) {
                snd_hwdep_free(hwdep);
                return err;
        }

        if (rhwdep)
                *rhwdep = hwdep;
        return 0;
}
EXPORT_SYMBOL(snd_hwdep_new);

static int snd_hwdep_dev_free(struct snd_device *device)
{
        snd_hwdep_free(device->device_data);
        return 0;
}

static int snd_hwdep_dev_register(struct snd_device *device)
{
        struct snd_hwdep *hwdep = device->device_data;
        struct snd_card *card = hwdep->card;
        int err;

        guard(mutex)(&register_mutex);
        if (snd_hwdep_search(card, hwdep->device))
                return -EBUSY;
        list_add_tail(&hwdep->list, &snd_hwdep_devices);
        err = snd_register_device(SNDRV_DEVICE_TYPE_HWDEP,
                                  hwdep->card, hwdep->device,
                                  &snd_hwdep_f_ops, hwdep, hwdep->dev);
        if (err < 0) {
                dev_err(hwdep->dev, "unable to register\n");
                list_del(&hwdep->list);
                return err;
        }

#ifdef CONFIG_SND_OSSEMUL
        hwdep->ossreg = 0;
        if (hwdep->oss_type >= 0) {
                if (hwdep->oss_type == SNDRV_OSS_DEVICE_TYPE_DMFM &&
                    hwdep->device)
                        dev_warn(hwdep->dev,
                                 "only hwdep device 0 can be registered as OSS direct FM device!\n");
                else if (snd_register_oss_device(hwdep->oss_type,
                                                 card, hwdep->device,
                                                 &snd_hwdep_f_ops, hwdep) < 0)
                        dev_warn(hwdep->dev,
                                 "unable to register OSS compatibility device\n");
                else
                        hwdep->ossreg = 1;
        }
#endif
        return 0;
}

static int snd_hwdep_dev_disconnect(struct snd_device *device)
{
        struct snd_hwdep *hwdep = device->device_data;

        if (snd_BUG_ON(!hwdep))
                return -ENXIO;
        guard(mutex)(&register_mutex);
        if (snd_hwdep_search(hwdep->card, hwdep->device) != hwdep)
                return -EINVAL;
        guard(mutex)(&hwdep->open_mutex);
        wake_up(&hwdep->open_wait);
#ifdef CONFIG_SND_OSSEMUL
        if (hwdep->ossreg)
                snd_unregister_oss_device(hwdep->oss_type, hwdep->card, hwdep->device);
#endif
        snd_unregister_device(hwdep->dev);
        list_del_init(&hwdep->list);
        return 0;
}

#ifdef CONFIG_SND_PROC_FS
/*
 *  Info interface
 */

static void snd_hwdep_proc_read(struct snd_info_entry *entry,
                                struct snd_info_buffer *buffer)
{
        struct snd_hwdep *hwdep;

        guard(mutex)(&register_mutex);
        list_for_each_entry(hwdep, &snd_hwdep_devices, list)
                snd_iprintf(buffer, "%02i-%02i: %s\n",
                            hwdep->card->number, hwdep->device, hwdep->name);
}

static struct snd_info_entry *snd_hwdep_proc_entry;

static void __init snd_hwdep_proc_init(void)
{
        struct snd_info_entry *entry;

        entry = snd_info_create_module_entry(THIS_MODULE, "hwdep", NULL);
        if (entry) {
                entry->c.text.read = snd_hwdep_proc_read;
                if (snd_info_register(entry) < 0) {
                        snd_info_free_entry(entry);
                        entry = NULL;
                }
        }
        snd_hwdep_proc_entry = entry;
}

static void __exit snd_hwdep_proc_done(void)
{
        snd_info_free_entry(snd_hwdep_proc_entry);
}
#else /* !CONFIG_SND_PROC_FS */
#define snd_hwdep_proc_init()
#define snd_hwdep_proc_done()
#endif /* CONFIG_SND_PROC_FS */


/*
 *  ENTRY functions
 */

static int __init alsa_hwdep_init(void)
{
        snd_hwdep_proc_init();
        snd_ctl_register_ioctl(snd_hwdep_control_ioctl);
        snd_ctl_register_ioctl_compat(snd_hwdep_control_ioctl);
        return 0;
}

static void __exit alsa_hwdep_exit(void)
{
        snd_ctl_unregister_ioctl(snd_hwdep_control_ioctl);
        snd_ctl_unregister_ioctl_compat(snd_hwdep_control_ioctl);
        snd_hwdep_proc_done();
}

module_init(alsa_hwdep_init)
module_exit(alsa_hwdep_exit)