/**
 * 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_del(&entry->list);
                list_add(&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 = vm->ptp[0];
        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 (kmalloced) addr of the @index-th device
 * page talbe page on success, or NULL on failure.
 * The first returned NULL indicates the termination.
 * */
static void *
ct_get_ptp_virt(struct ct_vm *vm, int index)
{
        void *addr;

        addr = (index >= CT_PTP_NUM) ? NULL : vm->ptp[index];

        return addr;
}

int ct_vm_create(struct ct_vm **rvm)
{
        struct ct_vm *vm;
        struct ct_vm_block *block;
        int i;

        *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++) {
                vm->ptp[i] = kmalloc(PAGE_SIZE, GFP_KERNEL);
                if (!vm->ptp[i])
                        break;
        }
        if (!i) {
                /* no page table pages are allocated */
                kfree(vm);
                return -ENOMEM;
        }
        vm->size = CT_ADDRS_PER_PAGE * i;
        /* Initialise remaining ptps */
        for (; i < CT_PTP_NUM; i++)
                vm->ptp[i] = NULL;

        vm->map = ct_vm_map;
        vm->unmap = ct_vm_unmap;
        vm->get_ptp_virt = ct_get_ptp_virt;
        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++)
                kfree(vm->ptp[i]);

        vm->size = 0;

        kfree(vm);
}