linux/sound/firewire/iso-resources.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * isochronous resources helper functions
 *
 * Copyright (c) Clemens Ladisch <[email protected]>
 */

#include <linux/device.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include "iso-resources.h"

/**
 * fw_iso_resources_init - initializes a &struct fw_iso_resources
 * @r: the resource manager to initialize
 * @unit: the device unit for which the resources will be needed
 *
 * If the device does not support all channel numbers, change @r->channels_mask
 * after calling this function.
 */
int fw_iso_resources_init(struct fw_iso_resources *r, struct fw_unit *unit)
{ … }
EXPORT_SYMBOL(…);

/**
 * fw_iso_resources_destroy - destroy a resource manager
 * @r: the resource manager that is no longer needed
 */
void fw_iso_resources_destroy(struct fw_iso_resources *r)
{ … }
EXPORT_SYMBOL(…);

static unsigned int packet_bandwidth(unsigned int max_payload_bytes, int speed)
{ … }

static int current_bandwidth_overhead(struct fw_card *card)
{ … }

static int wait_isoch_resource_delay_after_bus_reset(struct fw_card *card)
{ … }

/**
 * fw_iso_resources_allocate - allocate isochronous channel and bandwidth
 * @r: the resource manager
 * @max_payload_bytes: the amount of data (including CIP headers) per packet
 * @speed: the speed (e.g., SCODE_400) at which the packets will be sent
 *
 * This function allocates one isochronous channel and enough bandwidth for the
 * specified packet size.
 *
 * Returns the channel number that the caller must use for streaming, or
 * a negative error code.  Due to potentionally long delays, this function is
 * interruptible and can return -ERESTARTSYS.  On success, the caller is
 * responsible for calling fw_iso_resources_update() on bus resets, and
 * fw_iso_resources_free() when the resources are not longer needed.
 */
int fw_iso_resources_allocate(struct fw_iso_resources *r,
			      unsigned int max_payload_bytes, int speed)
{ … }
EXPORT_SYMBOL(…);

/**
 * fw_iso_resources_update - update resource allocations after a bus reset
 * @r: the resource manager
 *
 * This function must be called from the driver's .update handler to reallocate
 * any resources that were allocated before the bus reset.  It is safe to call
 * this function if no resources are currently allocated.
 *
 * Returns a negative error code on failure.  If this happens, the caller must
 * stop streaming.
 */
int fw_iso_resources_update(struct fw_iso_resources *r)
{ … }
EXPORT_SYMBOL(…);

/**
 * fw_iso_resources_free - frees allocated resources
 * @r: the resource manager
 *
 * This function deallocates the channel and bandwidth, if allocated.
 */
void fw_iso_resources_free(struct fw_iso_resources *r)
{ … }
EXPORT_SYMBOL(…);