/* 
 * 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. 
 */

#include <metalsvm/stdio.h>
#include <metalsvm/string.h>
#include <metalsvm/stdlib.h>
#include <metalsvm/mmu.h>
#include <metalsvm/spinlock.h>
#include <metalsvm/time.h>
#include <metalsvm/processor.h>
#include <metalsvm/page.h>
#include <metalsvm/errno.h>
#ifdef CONFIG_MULTIBOOT
#include <asm/multiboot.h>
#endif
#ifdef CONFIG_ROCKCREEK
#include <asm/RCCE.h>
#include <asm/RCCE_lib.h>
#include <asm/SCC_API.h>
#include <asm/icc.h>
#endif

/* 
 * Set whole address space as occupied:
 * 0 => free, 1 => occupied
 */
static uint8_t bitmap[BITMAP_SIZE] = {[0 ... BITMAP_SIZE-1] = 0xFF};
static spinlock_t bitmap_lock = SPINLOCK_INIT;

atomic_int32_t total_pages = ATOMIC_INIT(0);
atomic_int32_t total_allocated_pages = ATOMIC_INIT(0);
atomic_int32_t total_available_pages = ATOMIC_INIT(0);

/* 
 * Note that linker symbols are not variables, they have no memory allocated for
 * maintaining a value, rather their address is their value.
 */
extern const void kernel_start;
extern const void kernel_end;

inline static int page_marked(size_t i)
{
	size_t index = i >> 3;
	size_t mod = i & 0x7;

	return  (bitmap[index] & (1 << mod));
}

inline static int page_unmarked(size_t i)
{
	return !page_marked(i);
}

inline static void page_set_mark(size_t i)
{
	size_t index = i >> 3;
	size_t mod = i & 0x7;

	if (page_marked(i))
		kprintf("page_set_mark(%u): already marked\n", i);

        bitmap[index] = bitmap[index] | (1 << mod);
}

inline static void page_clear_mark(size_t i)
{
	size_t index = i / 8;
	size_t mod = i % 8;

	if (page_unmarked(i))
		kprintf("page_clear_mark(%u): already unmarked\n", i);

	bitmap[index] = bitmap[index] & ~(1 << mod);
}

size_t get_pages(uint32_t npages)
{
	// skip first page
	static size_t start = 1;

	uint32_t i, j, l;
	uint32_t k = 0;
	size_t ret = 0;

	if (BUILTIN_EXPECT(!npages, 0))
		return ret;

	if (BUILTIN_EXPECT(npages > atomic_int32_read(&total_available_pages), 0))
		return ret;

	spinlock_lock(&bitmap_lock);
	i = start;
next_try:
	while((k < BITMAP_SIZE) && page_marked(i)) {
		k++;
		i = (i+1) & (BITMAP_SIZE-1);
	}

	if (k >= BITMAP_SIZE)
		goto oom;

	for(j=1; (j<npages) && (i+j < BITMAP_SIZE) && (k < BITMAP_SIZE); j++, k++) {
		if (page_marked(i+j)) {
			i = (i+j) & (BITMAP_SIZE-1);
			goto next_try;
		}
	}

	if (i+j >= BITMAP_SIZE) {
		i = 1;
		goto next_try;
	}

	if (k >= BITMAP_SIZE)
		goto oom;

	ret = i*PAGE_SIZE;
	kprintf("get_pages: ret 0x%x, i = %d, j = %d, npages = %d\n", ret, i, j, npages); // TODO: remove
	for(l=i; l<i+j; l++)
		page_set_mark(l);

	start = i+j;
	spinlock_unlock(&bitmap_lock);

	atomic_int32_add(&total_allocated_pages, npages);
	atomic_int32_sub(&total_available_pages, npages);

	return ret;

oom:
	spinlock_unlock(&bitmap_lock);

	return ret;
}

int put_pages(size_t phyaddr, size_t npages)
{
	if (BUILTIN_EXPECT(!phyaddr || !npages, 0))
		return -EINVAL;

	uint32_t index;
	uint32_t base = phyaddr >> PAGE_SHIFT;

	spinlock_lock(&bitmap_lock);
	for (index=0; index<npages; index++)
		page_clear_mark(base+index);
	spinlock_unlock(&bitmap_lock);

	atomic_int32_sub(&total_allocated_pages, npages);
	atomic_int32_add(&total_available_pages, npages);

	return 0;
}

int mmu_init(void)
{
	unsigned int i; 
	size_t addr;
	int ret = 0;

#ifdef CONFIG_MULTIBOOT
	if (mb_info) {
		if (mb_info->flags & MULTIBOOT_INFO_MEM_MAP) {
			multiboot_memory_map_t* mmap = (multiboot_memory_map_t*) ((size_t) mb_info->mmap_addr);
			multiboot_memory_map_t* mmap_end = (void*) ((size_t) mb_info->mmap_addr + mb_info->mmap_length);

			// mark available memory as free
			while (mmap < mmap_end) {
				if (mmap->type == MULTIBOOT_MEMORY_AVAILABLE) {
					for (addr=mmap->addr; addr < mmap->addr + mmap->len; addr += PAGE_SIZE) {
						page_clear_mark(addr >> PAGE_SHIFT);
						atomic_int32_inc(&total_pages);
						atomic_int32_inc(&total_available_pages);
					}
				}
				mmap++;
			}
		}
		else if (mb_info->flags & MULTIBOOT_INFO_MEM) {
			size_t page;
			size_t pages_lower = mb_info->mem_lower >> 2;
			size_t pages_upper = mb_info->mem_upper >> 2;

			for (page=0; page<pages_lower; page++)
				page_clear_mark(page);

			for (page=0x100000; page<pages_upper+0x100000; page++)
				page_clear_mark(page);

			atomic_int32_add(&total_pages, pages_lower + pages_upper);
			atomic_int32_add(&total_available_pages, pages_lower + pages_upper);
		}
		else {
			kputs("Unable to initialize the memory management subsystem\n");
			while (1) HALT;
		}

		// mark mb_info as used
		page_set_mark((size_t) mb_info >> PAGE_SHIFT);
		atomic_int32_inc(&total_allocated_pages);
		atomic_int32_dec(&total_available_pages);

		// mark modules list as used
		if (mb_info->flags & MULTIBOOT_INFO_MODS) {
			for(addr=mb_info->mods_addr; addr<mb_info->mods_addr+mb_info->mods_count*sizeof(multiboot_module_t); addr+=PAGE_SIZE) {
				page_set_mark(addr >> PAGE_SHIFT);
				atomic_int32_inc(&total_allocated_pages);
				atomic_int32_dec(&total_available_pages);
			}
		}
	}
#elif defined(CONFIG_ROCKCREEK)
	// of course, the first slots belong to the private memory
	for(addr=0x00; addr<1*0x1000000; addr+=PAGE_SIZE) {
		page_clear_mark(addr >> PAGE_SHIFT);
		if (addr > addr + PAGE_SIZE)
			break;
		atomic_int32_inc(&total_pages);
		atomic_int32_inc(&total_available_pages);
	}

	// Note: The last slot belongs always to the private memory.
	for(addr=0xFF000000; addr<0xFFFFFFFF; addr+=PAGE_SIZE) {
		page_clear_mark(addr >> PAGE_SHIFT);
		if (addr > addr + PAGE_SIZE)
			break;
		atomic_int32_inc(&total_pages);
		atomic_int32_inc(&total_available_pages);
	}

	// mark the bootinfo as used.
	page_set_mark((size_t)bootinfo >> PAGE_SHIFT);
	atomic_int32_inc(&total_allocated_pages);
	atomic_int32_dec(&total_available_pages);
#else
	#error Currently, MetalSVM supports only the Multiboot specification or the RockCreek processor!
#endif

	// mark kernel as used
	for(addr=(size_t) &kernel_start; addr<(size_t) &kernel_end; addr+=PAGE_SIZE) {
		page_set_mark(addr >> PAGE_SHIFT);
		atomic_int32_inc(&total_allocated_pages);
		atomic_int32_dec(&total_available_pages);
	}

#if MAX_CORES > 1
	page_set_mark(SMP_SETUP_ADDR >> PAGE_SHIFT);
	atomic_int32_inc(&total_allocated_pages);
	atomic_int32_dec(&total_available_pages);
#endif

	// enable paging and map SMP, VGA, Multiboot modules etc.
	ret = paging_init();
	if (ret) {
		kprintf("Failed to initialize paging: %d\n", ret);
		return ret;
	}

	// add kernel to VMA list
	vma_add((size_t) &kernel_start & PAGE_MASK,
		PAGE_ALIGN((size_t) &kernel_end),
		VMA_READ|VMA_WRITE|VMA_EXECUTE|VMA_CACHEABLE);

	// add LAPIC tp VMA list
	vma_add((size_t) &kernel_start - PAGE_SIZE,
		(size_t) &kernel_start,
		VMA_READ|VMA_WRITE);

#if MAX_CORES > 1
	// reserve page for SMP boot code
	vma_add(SMP_SETUP_ADDR & PAGE_MASK,
		PAGE_ALIGN(SMP_SETUP_ADDR + PAGE_SIZE),
		VMA_READ|VMA_WRITE|VMA_EXECUTE|VMA_CACHEABLE);
#endif

#ifdef CONFIG_MULTIBOOT
	/* 
	 * Modules like the init ram disk are already loaded.
	 * Therefore, we set these pages as used.
	 */
	if (mb_info) {
		vma_add((size_t) mb_info & PAGE_MASK,
			PAGE_ALIGN((size_t) mb_info + sizeof(multiboot_info_t)),
			VMA_READ|VMA_CACHEABLE);

		if (mb_info->flags & MULTIBOOT_INFO_MODS) {
			multiboot_module_t* mmodule = (multiboot_module_t*) ((size_t) mb_info->mods_addr);

			vma_add((size_t) mb_info->mods_addr & PAGE_MASK,
				PAGE_ALIGN((size_t) mb_info->mods_addr + mb_info->mods_count*sizeof(multiboot_module_t)),
				VMA_READ|VMA_CACHEABLE);

			for(i=0; i<mb_info->mods_count; i++) {
				vma_add(PAGE_ALIGN(mmodule[i].mod_start),
					PAGE_ALIGN(mmodule[i].mod_end),
					VMA_READ|VMA_WRITE|VMA_CACHEABLE);

				for(addr=mmodule[i].mod_start; addr<mmodule[i].mod_end; addr+=PAGE_SIZE) {
					page_set_mark(addr >> PAGE_SHIFT);
					atomic_int32_inc(&total_allocated_pages);
					atomic_int32_dec(&total_available_pages);
				}
			}
		}
	}
#elif defined(CONFIG_ROCKCREEK)
	/*
	 * Now, we are able to read the FPGA registers and to
	 * determine the number of slots for private memory.
	 */
	uint32_t slots = *((volatile uint8_t*) (FPGA_BASE + 0x8244));
	if (slots == 0)
		slots = 1;

	kprintf("MetalSVM use %d slots for private memory\n", slots);

	// define the residual private slots as free
	for(addr=1*0x1000000; addr<slots*0x1000000; addr+=PAGE_SIZE) {
		page_clear_mark(addr >> PAGE_SHIFT);
		if (addr > addr + PAGE_SIZE)
			break;
		atomic_int32_inc(&total_pages);
		atomic_int32_inc(&total_available_pages);
	}

	/* 
	 * The init ram disk are already loaded.
	 * Therefore, we set these pages as used.
	 */
	for(addr=bootinfo->addr; addr<bootinfo->addr+bootinfo->size; addr+=PAGE_SIZE) {
		// this area is already mapped, so we need to virt_to_phys() these addresses.
		page_set_mark(virt_to_phys(addr) >> PAGE_SHIFT);
		atomic_int32_inc(&total_allocated_pages);
		atomic_int32_dec(&total_available_pages);
	}
#endif

	return ret;
}

void* mem_allocation(size_t sz, uint32_t flags)
{
	size_t phyaddr, viraddr;
	uint32_t npages = sz >> PAGE_SHIFT;

	if (sz & (PAGE_SIZE-1))
		npages++;

	phyaddr = get_pages(npages);
	if (BUILTIN_EXPECT(!phyaddr, 0))
		return 0;

	viraddr = map_region(0, phyaddr, npages, flags);

	return (void*) viraddr;
}

void* kmalloc(size_t sz)
{
	return mem_allocation(sz, MAP_KERNEL_SPACE);
}

void kfree(void* addr, size_t sz)
{
	uint32_t index, npages, i;
	size_t phyaddr;

	if (BUILTIN_EXPECT(!addr && !sz, 0))
		return;

        npages = sz >> PAGE_SHIFT;
	if (sz & (PAGE_SIZE-1))
		npages++;

	spinlock_lock(&bitmap_lock);
	for(i=0; i<npages; i++) {
		unmap_region((size_t) addr+i*PAGE_SIZE, 1);

		phyaddr = virt_to_phys((size_t) addr+i*PAGE_SIZE);
		if (!phyaddr)
			continue;

		index = phyaddr >> PAGE_SHIFT;
		page_clear_mark(index);
	}
	spinlock_unlock(&bitmap_lock);

	vm_free((size_t) addr, npages);

	atomic_int32_sub(&total_allocated_pages, npages);
	atomic_int32_add(&total_available_pages, npages);
}

void* create_stack(void)
{
	return kmalloc(KERNEL_STACK_SIZE);
}

int destroy_stack(task_t* task)
{
	if (BUILTIN_EXPECT(!task || !task->stack, 0))
		return -EINVAL;

	kfree(task->stack, KERNEL_STACK_SIZE);

	return 0;
}