/* 
 * Copyright 2010 Stefan Lankes, Chair for Operating Systems,
 *                               RWTH Aachen University
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This file is part of MetalSVM.
 */

/*
 * Defines the interface for and structures relating to paging.
 */

#ifndef __ARCH_PAGE_H__
#define __ARCH_PAGE_H__

#include <metalsvm/stddef.h>
//#include <metalsvm/tasks_types.h>
#include <metalsvm/stdlib.h>

#define _PAGE_BIT_PRESENT	0	/* is present */
#define _PAGE_BIT_RW		1	/* writeable */
#define _PAGE_BIT_USER		2	/* userspace addressable */
#define _PAGE_BIT_PWT		3	/* page write through */
#define _PAGE_BIT_PCD		4	/* page cache disabled */
#define _PAGE_BIT_ACCESSED	5	/* was accessed (raised by CPU) */
#define _PAGE_BIT_DIRTY		6	/* was written to (raised by CPU) */
#define _PAGE_BIT_PSE		7	/* 4 MB (or 2MB) page */
#define _PAGE_BIT_PAT		7	/* on 4KB pages */
#define _PAGE_BIT_GLOBAL	8	/* Global TLB entry PPro+ */
#define _PAGE_BIT_RESERVED	9	/* mark a virtual address range as reserved */
#define _PAGE_BIT_PAT_LARGE	12	/* On 2MB or 1GB pages */

#define PG_PRESENT	(1 << _PAGE_BIT_PRESENT)
#define PG_RW		(1 << _PAGE_BIT_RW)
#define PG_USER		(1 << _PAGE_BIT_USER)
#define PG_PWT		(1 << _PAGE_BIT_PWT)
#define PG_PCD		(1 << _PAGE_BIT_PCD)
#define PG_ACCESSED	(1 << _PAGE_BIT_ACCESSED)
#define PG_DIRTY	(1 << _PAGE_BIT_DIRTY)
#define PG_PSE		(1 << _PAGE_BIT_PSE)
#define PG_GLOBAL	(1 << _PAGE_BIT_GLOBAL)
#define PG_RESERVED	(1 << _PAGE_BIT_RESERVED)
#define PG_PAT		(1 << _PAGE_BIT_PAT)
#define PG_PAT_LARGE	(1 << _PAGE_BIT_PAT_LARGE)

#define KERN_TABLE	(PG_PRESENT|PG_RW|PG_ACCESSED|PG_DIRTY)
#define USER_TABLE	(PG_PRESENT|PG_RW|PG_ACCESSED|PG_DIRTY|PG_USER)
#define KERN_PAGE	(PG_PRESENT|PG_RW|PG_GLOBAL)
#define USER_PAGE	(PG_PRESENT|PG_RW|PG_USER)
 
typedef struct page_table
{
	uint32_t entries[1024];
} page_table_t __attribute__ ((aligned (4096)));

typedef struct page_dir
{
	uint32_t entries[1024];
} page_dir_t __attribute__ ((aligned (4096)));

/*
 * Converts a virtual address to a physical
 */
size_t virt_to_phys(size_t);

/*
 * Allocates an virtual address space range of npages
 */
size_t vm_alloc(uint32_t npages, uint32_t flags);

/*
 * Frees a range in the virtual address space
 */
int vm_free(size_t addr, uint32_t npages);

/*
 * Maps a physical memory region at a specific virtual address.
 * If the virtual address is zero, this functions allocates a valid virtual address on demand.
 */
size_t map_region(size_t viraddr, size_t phyaddr, uint32_t pages, uint32_t type);

/*
 * Sets up the environment and enables paging.
 */
int arch_paging_init(void);

/*
 * Returns the page directory of the boot task
 */
page_dir_t* get_boot_pgd(void);

/*
 * Setup a new page directory for a new user-level task
 */
int create_pgd(task_t* task, int copy);

/*
 * Delete page directory and its page tables
 */
int drop_pgd(void);

/*
 * Change the page permission in the page tables of the current task
 */
int change_page_permissions(size_t start, size_t end, uint32_t flags);

#endif