/*
 * Simple kernel memory allocator built on top of memcache
 * implementation.
 *
 * Copyright (C) 2007 Bahadir Balban
 */
#include <l4/lib/memcache.h>
#include <l4/lib/list.h>
#include <l4/generic/space.h>
#include <l4/generic/kmalloc.h>
#include <l4/generic/pgalloc.h>
#include <l4/generic/physmem.h>
#include INC_GLUE(memory.h)

/* FIXME:
 *
 * mem_cache_alloc() now has an interruptible mutex.
 * All routines defined here should check returned errors.
 */

#define	PGALLOC_PGD_CACHE		0
#define PGALLOC_PMD_CACHE		1
#define PGALLOC_PG_CACHE		2
#define PGALLOC_CACHE_TOTAL		3

/* The initial chunk of physical memory allocated before any pagers. */
#define PGALLOC_INIT_GRANT		SZ_1MB

/* Covers 3 main types of memory needed by the kernel. */
struct pgalloc {
	struct link cache_list[3];
};
static struct pgalloc pgalloc;

void pgalloc_add_new_cache(struct mem_cache *cache, int cidx)
{
	link_init(&cache->list);
	BUG_ON(cidx >= PGALLOC_CACHE_TOTAL || cidx < 0);
	list_insert(&cache->list, &pgalloc.cache_list[cidx]);
}

void print_kmem_grant_params(grant_kmem_usage_t *params)
{
	printk("%s: %lu bytes physical memory granted.\n", __KERNELNAME__, params->total_size);
	printk("%s: Possible kmem usage on this memory grant:\n", __KERNELNAME__);
	printk("%s: PGDs: %lu, PMDs: %lu, TCBs: %lu, Extra: %lu bytes.\n", __KERNELNAME__,
	       params->total_pgds, params->total_pmds, params->total_tcbs,
	       params->extra);
}

#define TASK_AVERAGE_SIZE		SZ_16MB
#define TASK_AVERAGE_PMDS		TASK_AVERAGE_SIZE / PMD_MAP_SIZE

void calc_grant_kmem_usage(grant_kmem_usage_t *params, unsigned long total_size)
{
	/* Kmem usage per task */
	unsigned long task_avg_kmem_usage = PGD_SIZE + PMD_SIZE * 16 + PAGE_SIZE;
	unsigned long total_tasks = total_size / task_avg_kmem_usage;
	unsigned long extra = total_size - total_tasks * task_avg_kmem_usage;

	params->total_size = total_size;
	params->total_tasks = total_tasks;
	params->total_pgds = total_tasks;
	params->total_pmds = total_tasks * 16;
	params->total_tcbs = total_tasks;
	params->extra = extra;

	print_kmem_grant_params(params);
}


int pgalloc_add_new_grant(unsigned long pfn, int npages)
{
	unsigned long physical = __pfn_to_addr(pfn);
	void *virtual = (void *)phys_to_virt(physical);
	struct mem_cache *pgd_cache, *pmd_cache, *pg_cache;
	grant_kmem_usage_t params;

	/* First map the whole grant */
	add_mapping(physical, phys_to_virt(physical), __pfn_to_addr(npages),
		    MAP_SVC_RW_FLAGS);

	/* Calculate how to divide buffer into different caches */
	calc_grant_kmem_usage(&params, __pfn_to_addr(npages));

	/* Create the caches, least alignment-needing, most, then others. */
	pmd_cache = mem_cache_init(virtual, params.total_pmds * PMD_SIZE,
				   PMD_SIZE, 1);
	virtual += params.total_pmds * PMD_SIZE;

	pgd_cache = mem_cache_init(virtual, params.total_pgds * PGD_SIZE,
				   PGD_SIZE, 1);
	virtual += params.total_pgds * PGD_SIZE;

	pg_cache = mem_cache_init(virtual, params.total_tcbs * PAGE_SIZE
				  + params.extra, PAGE_SIZE, 1);

	/* Add the caches */
	pgalloc_add_new_cache(pgd_cache, PGALLOC_PGD_CACHE);
	pgalloc_add_new_cache(pmd_cache, PGALLOC_PMD_CACHE);
	pgalloc_add_new_cache(pg_cache, PGALLOC_PG_CACHE);

	return 0;
}

void init_pgalloc(void)
{
	int initial_grant = PGALLOC_INIT_GRANT;

	for (int i = 0; i < PGALLOC_CACHE_TOTAL; i++)
		link_init(&pgalloc.cache_list[i]);

	/* Grant ourselves with an initial chunk of physical memory */
	physmem.free_cur = page_align_up(physmem.free_cur);
	set_page_map(physmem.free_cur, __pfn(initial_grant), 1);
	pgalloc_add_new_grant(__pfn(physmem.free_cur), __pfn(initial_grant));
	physmem.free_cur += initial_grant;

	/* Activate kmalloc */
	init_kmalloc();
}

void pgalloc_remove_cache(struct mem_cache *cache)
{
	list_remove_init(&cache->list);
}

static inline void *pgalloc_from_cache(int cidx)
{
	struct mem_cache *cache, *n;

	list_foreach_removable_struct(cache, n, &pgalloc.cache_list[cidx], list)
		if (mem_cache_total_empty(cache))
			return mem_cache_zalloc(cache);
	return 0;
}

int kfree_to_cache(int cidx, void *virtual)
{
	struct mem_cache *cache, *n;

	list_foreach_removable_struct(cache, n, &pgalloc.cache_list[cidx], list)
		if (mem_cache_free(cache, virtual) == 0)
			return 0;
	return -1;
}

void *alloc_page(void)
{
	return pgalloc_from_cache(PGALLOC_PG_CACHE);
}

void *alloc_pmd(void)
{
	pmd_table_t *pmd;

	if (!(pmd = alloc_boot_pmd()))
		pmd = pgalloc_from_cache(PGALLOC_PMD_CACHE);

	return pmd;
}

void *alloc_pgd(void)
{
	return pgalloc_from_cache(PGALLOC_PGD_CACHE);
}

int free_page(void *v)
{
	return kfree_to_cache(PGALLOC_PG_CACHE, v);
}

int free_pmd(void *v)
{
	return kfree_to_cache(PGALLOC_PMD_CACHE, v);
}

int free_pgd(void *v)
{
	return kfree_to_cache(PGALLOC_PGD_CACHE, v);
}

void *zalloc_page(void)
{
	void *p;

	if (!(p	= alloc_page()))
		return 0;

	memset(p, 0, PAGE_SIZE);
	return p;
}