drivers/firewire/core-iso.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Isochronous I/O functionality:
  *   - Isochronous DMA context management
  *   - Isochronous bus resource management (channels, bandwidth), client side
  *
  * Copyright (C) 2006 Kristian Hoegsberg <krh@bitplanet.net>
  */

 #include <linux/dma-mapping.h>
 #include <linux/errno.h>
 #include <linux/firewire.h>
 #include <linux/firewire-constants.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 #include <linux/export.h>

 #include <asm/byteorder.h>

 #include "core.h"

 #include <trace/events/firewire.h>

 /*
  * Isochronous DMA context management
  */

 int fw_iso_buffer_alloc(struct fw_iso_buffer *buffer, int page_count)
 {
 	int i;

 	buffer->page_count = 0;
 	buffer->page_count_mapped = 0;
 	buffer->pages = kmalloc_array(page_count, sizeof(buffer->pages[0]),
 				      GFP_KERNEL);
 	if (buffer->pages == NULL)
 		return -ENOMEM;

 	for (i = 0; i < page_count; i++) {
 		buffer->pages[i] = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
 		if (buffer->pages[i] == NULL)
 			break;
 	}
 	buffer->page_count = i;
 	if (i < page_count) {
 		fw_iso_buffer_destroy(buffer, NULL);
 		return -ENOMEM;
 	}

 	return 0;
 }

 int fw_iso_buffer_map_dma(struct fw_iso_buffer *buffer, struct fw_card *card,
 			  enum dma_data_direction direction)
 {
 	dma_addr_t address;
 	int i;

 	buffer->direction = direction;

 	for (i = 0; i < buffer->page_count; i++) {
 		address = dma_map_page(card->device, buffer->pages[i],
 				       0, PAGE_SIZE, direction);
 		if (dma_mapping_error(card->device, address))
 			break;

 		set_page_private(buffer->pages[i], address);
 	}
 	buffer->page_count_mapped = i;
 	if (i < buffer->page_count)
 		return -ENOMEM;

 	return 0;
 }

 int fw_iso_buffer_init(struct fw_iso_buffer *buffer, struct fw_card *card,
 		       int page_count, enum dma_data_direction direction)
 {
 	int ret;

 	ret = fw_iso_buffer_alloc(buffer, page_count);
 	if (ret < 0)
 		return ret;

 	ret = fw_iso_buffer_map_dma(buffer, card, direction);
 	if (ret < 0)
 		fw_iso_buffer_destroy(buffer, card);

 	return ret;
 }
 EXPORT_SYMBOL(fw_iso_buffer_init);

 void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer,
 			   struct fw_card *card)
 {
 	int i;
 	dma_addr_t address;

 	for (i = 0; i < buffer->page_count_mapped; i++) {
 		address = page_private(buffer->pages[i]);
 		dma_unmap_page(card->device, address,
 			       PAGE_SIZE, buffer->direction);
 	}
 	for (i = 0; i < buffer->page_count; i++)
 		__free_page(buffer->pages[i]);

 	kfree(buffer->pages);
 	buffer->pages = NULL;
 	buffer->page_count = 0;
 	buffer->page_count_mapped = 0;
 }
 EXPORT_SYMBOL(fw_iso_buffer_destroy);

 /* Convert DMA address to offset into virtually contiguous buffer. */
 size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)
 {
 	size_t i;
 	dma_addr_t address;
 	ssize_t offset;

 	for (i = 0; i < buffer->page_count; i++) {
 		address = page_private(buffer->pages[i]);
 		offset = (ssize_t)completed - (ssize_t)address;
 		if (offset > 0 && offset <= PAGE_SIZE)
 			return (i << PAGE_SHIFT) + offset;
 	}

 	return 0;
 }

 struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
 		int type, int channel, int speed, size_t header_size,
 		fw_iso_callback_t callback, void *callback_data)
 {
 	struct fw_iso_context *ctx;

 	ctx = card->driver->allocate_iso_context(card,
 						 type, channel, header_size);
 	if (IS_ERR(ctx))
 		return ctx;

 	ctx->card = card;
 	ctx->type = type;
 	ctx->channel = channel;
 	ctx->speed = speed;
 	ctx->header_size = header_size;
 	ctx->callback.sc = callback;
 	ctx->callback_data = callback_data;

 	trace_isoc_outbound_allocate(ctx, channel, speed);
 	trace_isoc_inbound_single_allocate(ctx, channel, header_size);
 	trace_isoc_inbound_multiple_allocate(ctx);

 	return ctx;
 }
 EXPORT_SYMBOL(fw_iso_context_create);

 void fw_iso_context_destroy(struct fw_iso_context *ctx)
 {
 	trace_isoc_outbound_destroy(ctx);
 	trace_isoc_inbound_single_destroy(ctx);
 	trace_isoc_inbound_multiple_destroy(ctx);

 	ctx->card->driver->free_iso_context(ctx);
 }
 EXPORT_SYMBOL(fw_iso_context_destroy);

 int fw_iso_context_start(struct fw_iso_context *ctx,
 			 int cycle, int sync, int tags)
 {
 	trace_isoc_outbound_start(ctx, cycle);
 	trace_isoc_inbound_single_start(ctx, cycle, sync, tags);
 	trace_isoc_inbound_multiple_start(ctx, cycle, sync, tags);

 	return ctx->card->driver->start_iso(ctx, cycle, sync, tags);
 }
 EXPORT_SYMBOL(fw_iso_context_start);

 int fw_iso_context_set_channels(struct fw_iso_context *ctx, u64 *channels)
 {
 	trace_isoc_inbound_multiple_channels(ctx, *channels);

 	return ctx->card->driver->set_iso_channels(ctx, channels);
 }

 int fw_iso_context_queue(struct fw_iso_context *ctx,
 			 struct fw_iso_packet *packet,
 			 struct fw_iso_buffer *buffer,
 			 unsigned long payload)
 {
 	trace_isoc_outbound_queue(ctx, payload, packet);
 	trace_isoc_inbound_single_queue(ctx, payload, packet);
 	trace_isoc_inbound_multiple_queue(ctx, payload, packet);

 	return ctx->card->driver->queue_iso(ctx, packet, buffer, payload);
 }
 EXPORT_SYMBOL(fw_iso_context_queue);

 void fw_iso_context_queue_flush(struct fw_iso_context *ctx)
 {
 	trace_isoc_outbound_flush(ctx);
 	trace_isoc_inbound_single_flush(ctx);
 	trace_isoc_inbound_multiple_flush(ctx);

 	ctx->card->driver->flush_queue_iso(ctx);
 }
 EXPORT_SYMBOL(fw_iso_context_queue_flush);

 /**
  * fw_iso_context_flush_completions() - process isochronous context in current process context.
  * @ctx: the isochronous context
  *
  * Process the isochronous context in the current process context. The registered callback function
  * is called when a queued packet buffer with the interrupt flag is completed, either after
  * transmission in the IT context or after being filled in the IR context. Additionally, the
  * callback function is also called for the packet buffer completed at last. Furthermore, the
  * callback function is called as well when the header buffer in the context becomes full. If it is
  * required to process the context asynchronously, fw_iso_context_schedule_flush_completions() is
  * available instead.
  *
  * Context: Process context. May sleep due to disable_work_sync().
  */
 int fw_iso_context_flush_completions(struct fw_iso_context *ctx)
 {
 	int err;

 	trace_isoc_outbound_flush_completions(ctx);
 	trace_isoc_inbound_single_flush_completions(ctx);
 	trace_isoc_inbound_multiple_flush_completions(ctx);

 	might_sleep();

 	// Avoid dead lock due to programming mistake.
 	if (WARN_ON_ONCE(current_work() == &ctx->work))
 		return 0;

 	disable_work_sync(&ctx->work);

 	err = ctx->card->driver->flush_iso_completions(ctx);

 	enable_work(&ctx->work);

 	return err;
 }
 EXPORT_SYMBOL(fw_iso_context_flush_completions);

 int fw_iso_context_stop(struct fw_iso_context *ctx)
 {
 	int err;

 	trace_isoc_outbound_stop(ctx);
 	trace_isoc_inbound_single_stop(ctx);
 	trace_isoc_inbound_multiple_stop(ctx);

 	might_sleep();

 	// Avoid dead lock due to programming mistake.
 	if (WARN_ON_ONCE(current_work() == &ctx->work))
 		return 0;

 	err = ctx->card->driver->stop_iso(ctx);

 	cancel_work_sync(&ctx->work);

 	return err;
 }
 EXPORT_SYMBOL(fw_iso_context_stop);

 /*
  * Isochronous bus resource management (channels, bandwidth), client side
  */

 static int manage_bandwidth(struct fw_card *card, int irm_id, int generation,
 			    int bandwidth, bool allocate)
 {
 	int try, new, old = allocate ? BANDWIDTH_AVAILABLE_INITIAL : 0;
 	__be32 data[2];

 	/*
 	 * On a 1394a IRM with low contention, try < 1 is enough.
 	 * On a 1394-1995 IRM, we need at least try < 2.
 	 * Let's just do try < 5.
 	 */
 	for (try = 0; try < 5; try++) {
 		new = allocate ? old - bandwidth : old + bandwidth;
 		if (new < 0 || new > BANDWIDTH_AVAILABLE_INITIAL)
 			return -EBUSY;

 		data[0] = cpu_to_be32(old);
 		data[1] = cpu_to_be32(new);
 		switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
 				irm_id, generation, SCODE_100,
 				CSR_REGISTER_BASE + CSR_BANDWIDTH_AVAILABLE,
 				data, 8)) {
 		case RCODE_GENERATION:
 			/* A generation change frees all bandwidth. */
 			return allocate ? -EAGAIN : bandwidth;

 		case RCODE_COMPLETE:
 			if (be32_to_cpup(data) == old)
 				return bandwidth;

 			old = be32_to_cpup(data);
 			/* Fall through. */
 		}
 	}

 	return -EIO;
 }

 static int manage_channel(struct fw_card *card, int irm_id, int generation,
 		u32 channels_mask, u64 offset, bool allocate)
 {
 	__be32 bit, all, old;
 	__be32 data[2];
 	int channel, ret = -EIO, retry = 5;

 	old = all = allocate ? cpu_to_be32(~0) : 0;

 	for (channel = 0; channel < 32; channel++) {
 		if (!(channels_mask & 1 << channel))
 			continue;

 		ret = -EBUSY;

 		bit = cpu_to_be32(1 << (31 - channel));
 		if ((old & bit) != (all & bit))
 			continue;

 		data[0] = old;
 		data[1] = old ^ bit;
 		switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
 					   irm_id, generation, SCODE_100,
 					   offset, data, 8)) {
 		case RCODE_GENERATION:
 			/* A generation change frees all channels. */
 			return allocate ? -EAGAIN : channel;

 		case RCODE_COMPLETE:
 			if (data[0] == old)
 				return channel;

 			old = data[0];

 			/* Is the IRM 1394a-2000 compliant? */
 			if ((data[0] & bit) == (data[1] & bit))
 				continue;

 			fallthrough;	/* It's a 1394-1995 IRM, retry */
 		default:
 			if (retry) {
 				retry--;
 				channel--;
 			} else {
 				ret = -EIO;
 			}
 		}
 	}

 	return ret;
 }

 static void deallocate_channel(struct fw_card *card, int irm_id,
 			       int generation, int channel)
 {
 	u32 mask;
 	u64 offset;

 	mask = channel < 32 ? 1 << channel : 1 << (channel - 32);
 	offset = channel < 32 ? CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI :
 				CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO;

 	manage_channel(card, irm_id, generation, mask, offset, false);
 }

 /**
  * fw_iso_resource_manage() - Allocate or deallocate a channel and/or bandwidth
  * @card: card interface for this action
  * @generation: bus generation
  * @channels_mask: bitmask for channel allocation
  * @channel: pointer for returning channel allocation result
  * @bandwidth: pointer for returning bandwidth allocation result
  * @allocate: whether to allocate (true) or deallocate (false)
  *
  * In parameters: card, generation, channels_mask, bandwidth, allocate
  * Out parameters: channel, bandwidth
  *
  * This function blocks (sleeps) during communication with the IRM.
  *
  * Allocates or deallocates at most one channel out of channels_mask.
  * channels_mask is a bitfield with MSB for channel 63 and LSB for channel 0.
  * (Note, the IRM's CHANNELS_AVAILABLE is a big-endian bitfield with MSB for
  * channel 0 and LSB for channel 63.)
  * Allocates or deallocates as many bandwidth allocation units as specified.
  *
  * Returns channel < 0 if no channel was allocated or deallocated.
  * Returns bandwidth = 0 if no bandwidth was allocated or deallocated.
  *
  * If generation is stale, deallocations succeed but allocations fail with
  * channel = -EAGAIN.
  *
  * If channel allocation fails, no bandwidth will be allocated either.
  * If bandwidth allocation fails, no channel will be allocated either.
  * But deallocations of channel and bandwidth are tried independently
  * of each other's success.
  */
 void fw_iso_resource_manage(struct fw_card *card, int generation,
 			    u64 channels_mask, int *channel, int *bandwidth,
 			    bool allocate)
 {
 	u32 channels_hi = channels_mask;	/* channels 31...0 */
 	u32 channels_lo = channels_mask >> 32;	/* channels 63...32 */
 	int irm_id, ret, c = -EINVAL;

 	scoped_guard(spinlock_irq, &card->lock)
 		irm_id = card->irm_node->node_id;

 	if (channels_hi)
 		c = manage_channel(card, irm_id, generation, channels_hi,
 				CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI,
 				allocate);
 	if (channels_lo && c < 0) {
 		c = manage_channel(card, irm_id, generation, channels_lo,
 				CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO,
 				allocate);
 		if (c >= 0)
 			c += 32;
 	}
 	*channel = c;

 	if (allocate && channels_mask != 0 && c < 0)
 		*bandwidth = 0;

 	if (*bandwidth == 0)
 		return;

 	ret = manage_bandwidth(card, irm_id, generation, *bandwidth, allocate);
 	if (ret < 0)
 		*bandwidth = 0;

 	if (allocate && ret < 0) {
 		if (c >= 0)
 			deallocate_channel(card, irm_id, generation, c);
 		*channel = ret;
 	}
 }
 EXPORT_SYMBOL(fw_iso_resource_manage);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Isochronous I/O functionality:
	* - Isochronous DMA context management
	* - Isochronous bus resource management (channels, bandwidth), client side
	*
	* Copyright (C) 2006 Kristian Hoegsberg <krh@bitplanet.net>
	*/

	#include <linux/dma-mapping.h>
	#include <linux/errno.h>
	#include <linux/firewire.h>
	#include <linux/firewire-constants.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <linux/vmalloc.h>
	#include <linux/export.h>

	#include <asm/byteorder.h>

	#include "core.h"

	#include <trace/events/firewire.h>

	/*
	* Isochronous DMA context management
	*/

	int fw_iso_buffer_alloc(struct fw_iso_buffer *buffer, int page_count)
	{
	int i;

	buffer->page_count = 0;
	buffer->page_count_mapped = 0;
	buffer->pages = kmalloc_array(page_count, sizeof(buffer->pages[0]),
	GFP_KERNEL);
	if (buffer->pages == NULL)
	return -ENOMEM;

	for (i = 0; i < page_count; i++) {
	buffer->pages[i] = alloc_page(GFP_KERNEL \| GFP_DMA32 \| __GFP_ZERO);
	if (buffer->pages[i] == NULL)
	break;
	}
	buffer->page_count = i;
	if (i < page_count) {
	fw_iso_buffer_destroy(buffer, NULL);
	return -ENOMEM;
	}

	return 0;
	}

	int fw_iso_buffer_map_dma(struct fw_iso_buffer buffer, struct fw_card card,
	enum dma_data_direction direction)
	{
	dma_addr_t address;
	int i;

	buffer->direction = direction;

	for (i = 0; i < buffer->page_count; i++) {
	address = dma_map_page(card->device, buffer->pages[i],
	0, PAGE_SIZE, direction);
	if (dma_mapping_error(card->device, address))
	break;

	set_page_private(buffer->pages[i], address);
	}
	buffer->page_count_mapped = i;
	if (i < buffer->page_count)
	return -ENOMEM;

	return 0;
	}

	int fw_iso_buffer_init(struct fw_iso_buffer buffer, struct fw_card card,
	int page_count, enum dma_data_direction direction)
	{
	int ret;

	ret = fw_iso_buffer_alloc(buffer, page_count);
	if (ret < 0)
	return ret;

	ret = fw_iso_buffer_map_dma(buffer, card, direction);
	if (ret < 0)
	fw_iso_buffer_destroy(buffer, card);

	return ret;
	}
	EXPORT_SYMBOL(fw_iso_buffer_init);

	void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer,
	struct fw_card *card)
	{
	int i;
	dma_addr_t address;

	for (i = 0; i < buffer->page_count_mapped; i++) {
	address = page_private(buffer->pages[i]);
	dma_unmap_page(card->device, address,
	PAGE_SIZE, buffer->direction);
	}
	for (i = 0; i < buffer->page_count; i++)
	__free_page(buffer->pages[i]);

	kfree(buffer->pages);
	buffer->pages = NULL;
	buffer->page_count = 0;
	buffer->page_count_mapped = 0;
	}
	EXPORT_SYMBOL(fw_iso_buffer_destroy);

	/* Convert DMA address to offset into virtually contiguous buffer. */
	size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)
	{
	size_t i;
	dma_addr_t address;
	ssize_t offset;

	for (i = 0; i < buffer->page_count; i++) {
	address = page_private(buffer->pages[i]);
	offset = (ssize_t)completed - (ssize_t)address;
	if (offset > 0 && offset <= PAGE_SIZE)
	return (i << PAGE_SHIFT) + offset;
	}

	return 0;
	}

	struct fw_iso_context fw_iso_context_create(struct fw_card card,
	int type, int channel, int speed, size_t header_size,
	fw_iso_callback_t callback, void *callback_data)
	{
	struct fw_iso_context *ctx;

	ctx = card->driver->allocate_iso_context(card,
	type, channel, header_size);
	if (IS_ERR(ctx))
	return ctx;

	ctx->card = card;
	ctx->type = type;
	ctx->channel = channel;
	ctx->speed = speed;
	ctx->header_size = header_size;
	ctx->callback.sc = callback;
	ctx->callback_data = callback_data;

	trace_isoc_outbound_allocate(ctx, channel, speed);
	trace_isoc_inbound_single_allocate(ctx, channel, header_size);
	trace_isoc_inbound_multiple_allocate(ctx);

	return ctx;
	}
	EXPORT_SYMBOL(fw_iso_context_create);

	void fw_iso_context_destroy(struct fw_iso_context *ctx)
	{
	trace_isoc_outbound_destroy(ctx);
	trace_isoc_inbound_single_destroy(ctx);
	trace_isoc_inbound_multiple_destroy(ctx);

	ctx->card->driver->free_iso_context(ctx);
	}
	EXPORT_SYMBOL(fw_iso_context_destroy);

	int fw_iso_context_start(struct fw_iso_context *ctx,
	int cycle, int sync, int tags)
	{
	trace_isoc_outbound_start(ctx, cycle);
	trace_isoc_inbound_single_start(ctx, cycle, sync, tags);
	trace_isoc_inbound_multiple_start(ctx, cycle, sync, tags);

	return ctx->card->driver->start_iso(ctx, cycle, sync, tags);
	}
	EXPORT_SYMBOL(fw_iso_context_start);

	int fw_iso_context_set_channels(struct fw_iso_context ctx, u64 channels)
	{
	trace_isoc_inbound_multiple_channels(ctx, *channels);

	return ctx->card->driver->set_iso_channels(ctx, channels);
	}

	int fw_iso_context_queue(struct fw_iso_context *ctx,
	struct fw_iso_packet *packet,
	struct fw_iso_buffer *buffer,
	unsigned long payload)
	{
	trace_isoc_outbound_queue(ctx, payload, packet);
	trace_isoc_inbound_single_queue(ctx, payload, packet);
	trace_isoc_inbound_multiple_queue(ctx, payload, packet);

	return ctx->card->driver->queue_iso(ctx, packet, buffer, payload);
	}
	EXPORT_SYMBOL(fw_iso_context_queue);

	void fw_iso_context_queue_flush(struct fw_iso_context *ctx)
	{
	trace_isoc_outbound_flush(ctx);
	trace_isoc_inbound_single_flush(ctx);
	trace_isoc_inbound_multiple_flush(ctx);

	ctx->card->driver->flush_queue_iso(ctx);
	}
	EXPORT_SYMBOL(fw_iso_context_queue_flush);

	/**
	* fw_iso_context_flush_completions() - process isochronous context in current process context.
	* @ctx: the isochronous context
	*
	* Process the isochronous context in the current process context. The registered callback function
	* is called when a queued packet buffer with the interrupt flag is completed, either after
	* transmission in the IT context or after being filled in the IR context. Additionally, the
	* callback function is also called for the packet buffer completed at last. Furthermore, the
	* callback function is called as well when the header buffer in the context becomes full. If it is
	* required to process the context asynchronously, fw_iso_context_schedule_flush_completions() is
	* available instead.
	*
	* Context: Process context. May sleep due to disable_work_sync().
	*/
	int fw_iso_context_flush_completions(struct fw_iso_context *ctx)
	{
	int err;

	trace_isoc_outbound_flush_completions(ctx);
	trace_isoc_inbound_single_flush_completions(ctx);
	trace_isoc_inbound_multiple_flush_completions(ctx);

	might_sleep();

	// Avoid dead lock due to programming mistake.
	if (WARN_ON_ONCE(current_work() == &ctx->work))
	return 0;

	disable_work_sync(&ctx->work);

	err = ctx->card->driver->flush_iso_completions(ctx);

	enable_work(&ctx->work);

	return err;
	}
	EXPORT_SYMBOL(fw_iso_context_flush_completions);

	int fw_iso_context_stop(struct fw_iso_context *ctx)
	{
	int err;

	trace_isoc_outbound_stop(ctx);
	trace_isoc_inbound_single_stop(ctx);
	trace_isoc_inbound_multiple_stop(ctx);

	might_sleep();

	// Avoid dead lock due to programming mistake.
	if (WARN_ON_ONCE(current_work() == &ctx->work))
	return 0;

	err = ctx->card->driver->stop_iso(ctx);

	cancel_work_sync(&ctx->work);

	return err;
	}
	EXPORT_SYMBOL(fw_iso_context_stop);

	/*
	* Isochronous bus resource management (channels, bandwidth), client side
	*/

	static int manage_bandwidth(struct fw_card *card, int irm_id, int generation,
	int bandwidth, bool allocate)
	{
	int try, new, old = allocate ? BANDWIDTH_AVAILABLE_INITIAL : 0;
	__be32 data[2];

	/*
	* On a 1394a IRM with low contention, try < 1 is enough.
	* On a 1394-1995 IRM, we need at least try < 2.
	* Let's just do try < 5.
	*/
	for (try = 0; try < 5; try++) {
	new = allocate ? old - bandwidth : old + bandwidth;
	if (new < 0 \|\| new > BANDWIDTH_AVAILABLE_INITIAL)
	return -EBUSY;

	data[0] = cpu_to_be32(old);
	data[1] = cpu_to_be32(new);
	switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
	irm_id, generation, SCODE_100,
	CSR_REGISTER_BASE + CSR_BANDWIDTH_AVAILABLE,
	data, 8)) {
	case RCODE_GENERATION:
	/* A generation change frees all bandwidth. */
	return allocate ? -EAGAIN : bandwidth;

	case RCODE_COMPLETE:
	if (be32_to_cpup(data) == old)
	return bandwidth;

	old = be32_to_cpup(data);
	/* Fall through. */
	}
	}

	return -EIO;
	}

	static int manage_channel(struct fw_card *card, int irm_id, int generation,
	u32 channels_mask, u64 offset, bool allocate)
	{
	__be32 bit, all, old;
	__be32 data[2];
	int channel, ret = -EIO, retry = 5;

	old = all = allocate ? cpu_to_be32(~0) : 0;

	for (channel = 0; channel < 32; channel++) {
	if (!(channels_mask & 1 << channel))
	continue;

	ret = -EBUSY;

	bit = cpu_to_be32(1 << (31 - channel));
	if ((old & bit) != (all & bit))
	continue;

	data[0] = old;
	data[1] = old ^ bit;
	switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
	irm_id, generation, SCODE_100,
	offset, data, 8)) {
	case RCODE_GENERATION:
	/* A generation change frees all channels. */
	return allocate ? -EAGAIN : channel;

	case RCODE_COMPLETE:
	if (data[0] == old)
	return channel;

	old = data[0];

	/* Is the IRM 1394a-2000 compliant? */
	if ((data[0] & bit) == (data[1] & bit))
	continue;

	fallthrough; /* It's a 1394-1995 IRM, retry */
	default:
	if (retry) {
	retry--;
	channel--;
	} else {
	ret = -EIO;
	}
	}
	}

	return ret;
	}

	static void deallocate_channel(struct fw_card *card, int irm_id,
	int generation, int channel)
	{
	u32 mask;
	u64 offset;

	mask = channel < 32 ? 1 << channel : 1 << (channel - 32);
	offset = channel < 32 ? CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI :
	CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO;

	manage_channel(card, irm_id, generation, mask, offset, false);
	}

	/**
	* fw_iso_resource_manage() - Allocate or deallocate a channel and/or bandwidth
	* @card: card interface for this action
	* @generation: bus generation
	* @channels_mask: bitmask for channel allocation
	* @channel: pointer for returning channel allocation result
	* @bandwidth: pointer for returning bandwidth allocation result
	* @allocate: whether to allocate (true) or deallocate (false)
	*
	* In parameters: card, generation, channels_mask, bandwidth, allocate
	* Out parameters: channel, bandwidth
	*
	* This function blocks (sleeps) during communication with the IRM.
	*
	* Allocates or deallocates at most one channel out of channels_mask.
	* channels_mask is a bitfield with MSB for channel 63 and LSB for channel 0.
	* (Note, the IRM's CHANNELS_AVAILABLE is a big-endian bitfield with MSB for
	* channel 0 and LSB for channel 63.)
	* Allocates or deallocates as many bandwidth allocation units as specified.
	*
	* Returns channel < 0 if no channel was allocated or deallocated.
	* Returns bandwidth = 0 if no bandwidth was allocated or deallocated.
	*
	* If generation is stale, deallocations succeed but allocations fail with
	* channel = -EAGAIN.
	*
	* If channel allocation fails, no bandwidth will be allocated either.
	* If bandwidth allocation fails, no channel will be allocated either.
	* But deallocations of channel and bandwidth are tried independently
	* of each other's success.
	*/
	void fw_iso_resource_manage(struct fw_card *card, int generation,
	u64 channels_mask, int channel, int bandwidth,
	bool allocate)
	{
	u32 channels_hi = channels_mask; /* channels 31...0 */
	u32 channels_lo = channels_mask >> 32; /* channels 63...32 */
	int irm_id, ret, c = -EINVAL;

	scoped_guard(spinlock_irq, &card->lock)
	irm_id = card->irm_node->node_id;

	if (channels_hi)
	c = manage_channel(card, irm_id, generation, channels_hi,
	CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI,
	allocate);
	if (channels_lo && c < 0) {
	c = manage_channel(card, irm_id, generation, channels_lo,
	CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO,
	allocate);
	if (c >= 0)
	c += 32;
	}
	*channel = c;

	if (allocate && channels_mask != 0 && c < 0)
	*bandwidth = 0;

	if (*bandwidth == 0)
	return;

	ret = manage_bandwidth(card, irm_id, generation, *bandwidth, allocate);
	if (ret < 0)
	*bandwidth = 0;

	if (allocate && ret < 0) {
	if (c >= 0)
	deallocate_channel(card, irm_id, generation, c);
	*channel = ret;
	}
	}
	EXPORT_SYMBOL(fw_iso_resource_manage);