/**
 * 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 <asm/page.h>	/* for PAGE_SIZE macro definition */
#include <linux/io.h>
#include <asm/pgtable.h>

#define CT_PTES_PER_PAGE (PAGE_SIZE / sizeof(void *))
#define CT_ADDRS_PER_PAGE (CT_PTES_PER_PAGE * 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 = NULL;
	struct list_head *pos = NULL;

	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)
		return NULL;

	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;
		return entry;
	}

	block = kzalloc(sizeof(*block), GFP_KERNEL);
	if (NULL == block)
		return NULL;

	block->addr = entry->addr;
	block->size = size;
	list_add(&block->list, &vm->used);
	entry->addr += size;
	entry->size -= size;
	vm->size -= size;

	return block;
}

static void put_vm_block(struct ct_vm *vm, struct ct_vm_block *block)
{
	struct ct_vm_block *entry = NULL, *pre_ent = NULL;
	struct list_head *pos = NULL, *pre = NULL;

	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;
	}
}

/* Map host addr (kmalloced/vmalloced) to device logical addr. */
static struct ct_vm_block *
ct_vm_map(struct ct_vm *vm, void *host_addr, int size)
{
	struct ct_vm_block *block = NULL;
	unsigned long pte_start;
	unsigned long i;
	unsigned long pages;
	unsigned long start_phys;
	unsigned long *ptp;

	/* do mapping */
	if ((unsigned long)host_addr >= VMALLOC_START) {
		printk(KERN_ERR "Fail! Not support vmalloced addr now!\n");
		return NULL;
	}

	if (size > vm->size) {
		printk(KERN_ERR "Fail! No sufficient device virtural "
				  "memory space available!\n");
		return NULL;
	}

	start_phys = (virt_to_phys(host_addr) & PAGE_MASK);
	pages = (PAGE_ALIGN(virt_to_phys(host_addr) + size)
			- start_phys) >> PAGE_SHIFT;

	ptp = vm->ptp[0];

	block = get_vm_block(vm, (pages << PAGE_SHIFT));
	if (block == NULL) {
		printk(KERN_ERR "No virtual memory block that is big "
				  "enough to allocate!\n");
		return NULL;
	}

	pte_start = (block->addr >> PAGE_SHIFT);
	for (i = 0; i < pages; i++)
		ptp[pte_start+i] = start_phys + (i << PAGE_SHIFT);

	block->addr += (virt_to_phys(host_addr) & (~PAGE_MASK));
	block->size = size;

	return block;
}

static void ct_vm_unmap(struct ct_vm *vm, struct ct_vm_block *block)
{
	/* do unmapping */
	block->size = ((block->addr + block->size + PAGE_SIZE - 1)
			& PAGE_MASK) - (block->addr & PAGE_MASK);
	block->addr &= PAGE_MASK;
	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 (NULL == vm)
		return -ENOMEM;

	/* Allocate page table pages */
	for (i = 0; i < CT_PTP_NUM; i++) {
		vm->ptp[i] = kmalloc(PAGE_SIZE, GFP_KERNEL);
		if (NULL == 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 = NULL;
	struct ct_vm_block *entry = NULL;

	/* 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);
}