sound/firewire/dice/dice-hwdep.c

Source file repositories/reference/linux-study-clean/sound/firewire/dice/dice-hwdep.c

File Facts

System
Linux kernel
Corpus path
sound/firewire/dice/dice-hwdep.c
Extension
.c
Size
4161 bytes
Lines
173
Domain
Driver Families
Bucket
sound/firewire
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * dice_hwdep.c - a part of driver for DICE based devices
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 * Copyright (c) 2014 Takashi Sakamoto <o-takashi@sakamocchi.jp>
 */

#include "dice.h"

static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf,
			    long count, loff_t *offset)
{
	struct snd_dice *dice = hwdep->private_data;
	DEFINE_WAIT(wait);
	union snd_firewire_event event;

	spin_lock_irq(&dice->lock);

	while (!dice->dev_lock_changed && dice->notification_bits == 0) {
		prepare_to_wait(&dice->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
		spin_unlock_irq(&dice->lock);
		schedule();
		finish_wait(&dice->hwdep_wait, &wait);
		if (signal_pending(current))
			return -ERESTARTSYS;
		spin_lock_irq(&dice->lock);
	}

	memset(&event, 0, sizeof(event));
	if (dice->dev_lock_changed) {
		event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
		event.lock_status.status = dice->dev_lock_count > 0;
		dice->dev_lock_changed = false;

		count = min_t(long, count, sizeof(event.lock_status));
	} else {
		event.dice_notification.type =
					SNDRV_FIREWIRE_EVENT_DICE_NOTIFICATION;
		event.dice_notification.notification = dice->notification_bits;
		dice->notification_bits = 0;

		count = min_t(long, count, sizeof(event.dice_notification));
	}

	spin_unlock_irq(&dice->lock);

	if (copy_to_user(buf, &event, count))
		return -EFAULT;

	return count;
}

static __poll_t hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
			       poll_table *wait)
{
	struct snd_dice *dice = hwdep->private_data;

	poll_wait(file, &dice->hwdep_wait, wait);

	guard(spinlock_irq)(&dice->lock);
	if (dice->dev_lock_changed || dice->notification_bits != 0)
		return EPOLLIN | EPOLLRDNORM;
	else
		return 0;
}

static int hwdep_get_info(struct snd_dice *dice, void __user *arg)
{
	struct fw_device *dev = fw_parent_device(dice->unit);
	struct snd_firewire_get_info info;

	memset(&info, 0, sizeof(info));
	info.type = SNDRV_FIREWIRE_TYPE_DICE;
	info.card = dev->card->index;
	*(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]);
	*(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]);
	strscpy(info.device_name, dev_name(&dev->device),
		sizeof(info.device_name));

	if (copy_to_user(arg, &info, sizeof(info)))
		return -EFAULT;

	return 0;
}

static int hwdep_lock(struct snd_dice *dice)
{
	guard(spinlock_irq)(&dice->lock);

Annotation

Implementation Notes