sound/firewire/bebob/bebob_hwdep.c

Source file repositories/reference/linux-study-clean/sound/firewire/bebob/bebob_hwdep.c

File Facts

System
Linux kernel
Corpus path
sound/firewire/bebob/bebob_hwdep.c
Extension
.c
Size
3916 bytes
Lines
178
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
/*
 * bebob_hwdep.c - a part of driver for BeBoB based devices
 *
 * Copyright (c) 2013-2014 Takashi Sakamoto
 */

/*
 * This codes give three functionality.
 *
 * 1.get firewire node infomation
 * 2.get notification about starting/stopping stream
 * 3.lock/unlock stream
 */

#include "bebob.h"

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

	spin_lock_irq(&bebob->lock);

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

	memset(&event, 0, sizeof(event));
	count = min_t(long, count, sizeof(event.lock_status));
	event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
	event.lock_status.status = (bebob->dev_lock_count > 0);
	bebob->dev_lock_changed = false;

	spin_unlock_irq(&bebob->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_bebob *bebob = hwdep->private_data;

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

	guard(spinlock_irq)(&bebob->lock);
	if (bebob->dev_lock_changed)
		return EPOLLIN | EPOLLRDNORM;
	else
		return 0;
}

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

	memset(&info, 0, sizeof(info));
	info.type = SNDRV_FIREWIRE_TYPE_BEBOB;
	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_bebob *bebob)
{
	guard(spinlock_irq)(&bebob->lock);

Annotation

Implementation Notes