text: /**
   * Copyright (C) 2008, Creative Technology Ltd. All Rights Reserved.
   *
   * This source file is released under GPL v2 license (no other versions).
   * See the COPYING file included in the main directory of this source
   * distribution for the license terms and conditions.
   *
   * @File    ctvmem.c
   *
   * @Brief
   * This file contains the implementation of virtual memory management object
   * for card device.
   *
   * @Author Liu Chun
   * @Date Apr 1 2008
   */
  
  #include "ctvmem.h"
  #include <linux/slab.h>
  #include <linux/mm.h>
  #include <linux/io.h>
  #include <sound/pcm.h>
  
  #define CT_PTES_PER_PAGE (CT_PAGE_SIZE / sizeof(void *))
  #define CT_ADDRS_PER_PAGE (CT_PTES_PER_PAGE * CT_PAGE_SIZE)
  
  /* *
   * Find or create vm block based on requested @size.
   * @size must be page aligned.
   * */
  static struct ct_vm_block *
  get_vm_block(struct ct_vm *vm, unsigned int size)
  {
  	struct ct_vm_block *block = NULL, *entry;
  	struct list_head *pos;
  
  	size = CT_PAGE_ALIGN(size);
  	if (size > vm->size) {
  		printk(KERN_ERR "ctxfi: Fail! No sufficient device virtural "
  				  "memory space available!\n");
  		return NULL;
  	}
  
  	mutex_lock(&vm->lock);
  	list_for_each(pos, &vm->unused) {
  		entry = list_entry(pos, struct ct_vm_block, list);
  		if (entry->size >= size)
  			break; /* found a block that is big enough */
  	}
  	if (pos == &vm->unused)
  		goto out;
  
  	if (entry->size == size) {
  		/* Move the vm node from unused list to used list directly */
  		list_move(&entry->list, &vm->used);
  		vm->size -= size;
  		block = entry;
  		goto out;
  	}
  
  	block = kzalloc(sizeof(*block), GFP_KERNEL);
  	if (!block)
  		goto out;
  
  	block->addr = entry->addr;
  	block->size = size;
  	list_add(&block->list, &vm->used);
  	entry->addr += size;
  	entry->size -= size;
  	vm->size -= size;
  
   out:
  	mutex_unlock(&vm->lock);
  	return block;
  }
  
  static void put_vm_block(struct ct_vm *vm, struct ct_vm_block *block)
  {
  	struct ct_vm_block *entry, *pre_ent;
  	struct list_head *pos, *pre;
  
  	block->size = CT_PAGE_ALIGN(block->size);
  
  	mutex_lock(&vm->lock);
  	list_del(&block->list);
  	vm->size += block->size;
  
  	list_for_each(pos, &vm->unused) {
  		entry = list_entry(pos, struct ct_vm_block, list);
  		if (entry->addr >= (block->addr + block->size))
  			break; /* found a position */
  	}
  	if (pos == &vm->unused) {
  		list_add_tail(&block->list, &vm->unused);
  		entry = block;
  	} else {
  		if ((block->addr + block->size) == entry->addr) {
  			entry->addr = block->addr;
  			entry->size += block->size;
  			kfree(block);
  		} else {
  			__list_add(&block->list, pos->prev, pos);
  			entry = block;
  		}
  	}
  
  	pos = &entry->list;
  	pre = pos->prev;
  	while (pre != &vm->unused) {
  		entry = list_entry(pos, struct ct_vm_block, list);
  		pre_ent = list_entry(pre, struct ct_vm_block, list);
  		if ((pre_ent->addr + pre_ent->size) > entry->addr)
  			break;
  
  		pre_ent->size += entry->size;
  		list_del(pos);
  		kfree(entry);
  		pos = pre;
  		pre = pos->prev;
  	}
  	mutex_unlock(&vm->lock);
  }
  
  /* Map host addr (kmalloced/vmalloced) to device logical addr. */
  static struct ct_vm_block *
  ct_vm_map(struct ct_vm *vm, struct snd_pcm_substream *substream, int size)
  {
  	struct ct_vm_block *block;
  	unsigned int pte_start;
  	unsigned i, pages;
  	unsigned long *ptp;
  
  	block = get_vm_block(vm, size);
  	if (block == NULL) {
  		printk(KERN_ERR "ctxfi: No virtual memory block that is big "
  				  "enough to allocate!\n");
  		return NULL;
  	}
  
  	ptp = (unsigned long *)vm->ptp[0].area;
  	pte_start = (block->addr >> CT_PAGE_SHIFT);
  	pages = block->size >> CT_PAGE_SHIFT;
  	for (i = 0; i < pages; i++) {
  		unsigned long addr;
  		addr = snd_pcm_sgbuf_get_addr(substream, i << CT_PAGE_SHIFT);
  		ptp[pte_start + i] = addr;
  	}
  
  	block->size = size;
  	return block;
  }
  
  static void ct_vm_unmap(struct ct_vm *vm, struct ct_vm_block *block)
  {
  	/* do unmapping */
  	put_vm_block(vm, block);
  }
  
  /* *
   * return the host physical addr of the @index-th device
   * page table page on success, or ~0UL on failure.
   * The first returned ~0UL indicates the termination.
   * */
  static dma_addr_t
  ct_get_ptp_phys(struct ct_vm *vm, int index)
  {
  	dma_addr_t addr;
  
  	addr = (index >= CT_PTP_NUM) ? ~0UL : vm->ptp[index].addr;
  
  	return addr;
  }
  
  int ct_vm_create(struct ct_vm **rvm, struct pci_dev *pci)
  {
  	struct ct_vm *vm;
  	struct ct_vm_block *block;
  	int i, err = 0;
  
  	*rvm = NULL;
  
  	vm = kzalloc(sizeof(*vm), GFP_KERNEL);
  	if (!vm)
  		return -ENOMEM;
  
  	mutex_init(&vm->lock);
  
  	/* Allocate page table pages */
  	for (i = 0; i < CT_PTP_NUM; i++) {
  		err = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV,
  					  snd_dma_pci_data(pci),
  					  PAGE_SIZE, &vm->ptp[i]);
  		if (err < 0)
  			break;
  	}
  	if (err < 0) {
  		/* no page table pages are allocated */
  		ct_vm_destroy(vm);
  		return -ENOMEM;
  	}
  	vm->size = CT_ADDRS_PER_PAGE * i;
  	vm->map = ct_vm_map;
  	vm->unmap = ct_vm_unmap;
  	vm->get_ptp_phys = ct_get_ptp_phys;
  	INIT_LIST_HEAD(&vm->unused);
  	INIT_LIST_HEAD(&vm->used);
  	block = kzalloc(sizeof(*block), GFP_KERNEL);
  	if (NULL != block) {
  		block->addr = 0;
  		block->size = vm->size;
  		list_add(&block->list, &vm->unused);
  	}
  
  	*rvm = vm;
  	return 0;
  }
  
  /* The caller must ensure no mapping pages are being used
   * by hardware before calling this function */
  void ct_vm_destroy(struct ct_vm *vm)
  {
  	int i;
  	struct list_head *pos;
  	struct ct_vm_block *entry;
  
  	/* free used and unused list nodes */
  	while (!list_empty(&vm->used)) {
  		pos = vm->used.next;
  		list_del(pos);
  		entry = list_entry(pos, struct ct_vm_block, list);
  		kfree(entry);
  	}
  	while (!list_empty(&vm->unused)) {
  		pos = vm->unused.next;
  		list_del(pos);
  		entry = list_entry(pos, struct ct_vm_block, list);
  		kfree(entry);
  	}
  
  	/* free allocated page table pages */
  	for (i = 0; i < CT_PTP_NUM; i++)
  		snd_dma_free_pages(&vm->ptp[i]);
  
  	vm->size = 0;
  
  	kfree(vm);
  }
  