/*

   * Isochronous I/O functionality:
   *   - Isochronous DMA context management
   *   - Isochronous bus resource management (channels, bandwidth), client side

   *

   * Copyright (C) 2006 Kristian Hoegsberg <krh@bitplanet.net>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software Foundation,
   * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   */

  #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 <asm/byteorder.h>

  #include "core.h"

  
  /*
   * Isochronous DMA context management
   */

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

  {

  	int i, j;

  	dma_addr_t address;
  
  	buffer->page_count = page_count;
  	buffer->direction = direction;
  
  	buffer->pages = kmalloc(page_count * sizeof(buffer->pages[0]),
  				GFP_KERNEL);
  	if (buffer->pages == NULL)
  		goto out;
  
  	for (i = 0; i < buffer->page_count; i++) {

  		buffer->pages[i] = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);

  		if (buffer->pages[i] == NULL)
  			goto out_pages;

  		address = dma_map_page(card->device, buffer->pages[i],
  				       0, PAGE_SIZE, direction);

  		if (dma_mapping_error(card->device, address)) {

  			__free_page(buffer->pages[i]);
  			goto out_pages;
  		}
  		set_page_private(buffer->pages[i], address);

  	}
  
  	return 0;

   out_pages:
  	for (j = 0; j < i; j++) {
  		address = page_private(buffer->pages[j]);
  		dma_unmap_page(card->device, address,

  			       PAGE_SIZE, direction);

  		__free_page(buffer->pages[j]);
  	}
  	kfree(buffer->pages);
   out:
  	buffer->pages = NULL;

  	return -ENOMEM;

  }

  EXPORT_SYMBOL(fw_iso_buffer_init);

  
  int fw_iso_buffer_map(struct fw_iso_buffer *buffer, struct vm_area_struct *vma)
  {
  	unsigned long uaddr;

  	int i, err;

  
  	uaddr = vma->vm_start;
  	for (i = 0; i < buffer->page_count; i++) {

  		err = vm_insert_page(vma, uaddr, buffer->pages[i]);
  		if (err)
  			return err;

  		uaddr += PAGE_SIZE;
  	}
  
  	return 0;

  }

  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; i++) {
  		address = page_private(buffer->pages[i]);
  		dma_unmap_page(card->device, address,

  			       PAGE_SIZE, buffer->direction);

  		__free_page(buffer->pages[i]);
  	}

  	kfree(buffer->pages);
  	buffer->pages = NULL;

  }

  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)
  {
  	int 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;

  	return ctx;
  }

  EXPORT_SYMBOL(fw_iso_context_create);

  
  void fw_iso_context_destroy(struct fw_iso_context *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)

  {

  	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)
  {
  	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)

  {

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

  int fw_iso_context_stop(struct fw_iso_context *ctx)

  {
  	return ctx->card->driver->stop_iso(ctx);
  }

  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;
  
  			/* 1394-1995 IRM, fall through to 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

   *
   * 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;
  
  	spin_lock_irq(&card->lock);
  	irm_id = card->irm_node->node_id;
  	spin_unlock_irq(&card->lock);
  
  	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);