drivers/firewire/core-iso.c

// 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)
{
	struct page **page_array __free(kfree) = kzalloc_objs(page_array[0],
							      page_count,
							      GFP_KERNEL);

	if (!page_array)
		return -ENOMEM;

	// Retrieve noncontiguous pages. The descriptors for 1394 OHCI isochronous DMA contexts
	// have a set of address and length per each, while the reason to use pages is the
	// convenience to map them into virtual address space of user process.
	unsigned long nr_populated = alloc_pages_bulk(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO,
						      page_count, page_array);
	if (nr_populated != page_count) {
		// Assuming the above call fills page_array sequentially from the beginning.
		release_pages(page_array, nr_populated);
		return -ENOMEM;
	}

	buffer->page_count = page_count;
	buffer->pages = no_free_ptr(page_array);

	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 *dma_addrs __free(kfree) = kzalloc_objs(dma_addrs[0],
							   buffer->page_count,
							   GFP_KERNEL);
	int i;

	if (!dma_addrs)
		return -ENOMEM;

	// Retrieve DMA mapping addresses for the pages. They are not contiguous. Maintain the cache
	// coherency for the pages by hand.
	for (i = 0; i < buffer->page_count; i++) {
		// The dma_map_phys() with a physical address per page is available here, instead.
		dma_addr_t dma_addr = dma_map_page(card->device, buffer->pages[i], 0, PAGE_SIZE,
						   direction);
		if (dma_mapping_error(card->device, dma_addr))
			break;

		dma_addrs[i] = dma_addr;
	}
	if (i < buffer->page_count) {
		while (i-- > 0)
			dma_unmap_page(card->device, dma_addrs[i], PAGE_SIZE, buffer->direction);
		return -ENOMEM;
	}

	buffer->direction = direction;
	buffer->dma_addrs = no_free_ptr(dma_addrs);

	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)
{
	if (buffer->dma_addrs) {
		for (int i = 0; i < buffer->page_count; ++i) {
			dma_addr_t dma_addr = buffer->dma_addrs[i];
			dma_unmap_page(card->device, dma_addr, PAGE_SIZE, buffer->direction);
		}
		kfree(buffer->dma_addrs);
		buffer->dma_addrs = NULL;
	}

	if (buffer->pages) {
		release_pages(buffer->pages, buffer->page_count);
		kfree(buffer->pages);
		buffer->pages = NULL;
	}

	buffer->page_count = 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)
{
	for (int i = 0; i < buffer->page_count; i++) {
		dma_addr_t dma_addr = buffer->dma_addrs[i];
		ssize_t offset = (ssize_t)completed - (ssize_t)dma_addr;
		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, size_t header_storage_size,
		union fw_iso_callback callback, void *callback_data)
{
	struct fw_iso_context *ctx;

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

	ctx->card = card;
	ctx->type = type;
	ctx->channel = channel;
	ctx->speed = speed;
	ctx->flags = 0;
	ctx->header_size = header_size;
	ctx->header_storage_size = header_storage_size;
	ctx->callback = 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);