// SPDX-License-Identifier: GPL-2.0-only
#include <libcflat.h>
#include <devicetree.h>
#include <memregions.h>

static struct mem_region __initial_mem_regions[NR_INITIAL_MEM_REGIONS + 1];
static size_t nr_regions = NR_INITIAL_MEM_REGIONS;

struct mem_region *mem_regions = __initial_mem_regions;

void memregions_init(struct mem_region regions[], size_t nr)
{
	mem_regions = regions;
	nr_regions = nr;
}

struct mem_region *memregions_add(struct mem_region *r)
{
	struct mem_region *r_next = mem_regions;
	int i = 0;

	for (; r_next->end; ++r_next, ++i)
		;
	assert(i < nr_regions);

	*r_next = *r;

	return r_next;
}

struct mem_region *memregions_find(phys_addr_t paddr)
{
	struct mem_region *r;

	for (r = mem_regions; r->end; ++r)
		if (paddr >= r->start && paddr < r->end)
			return r;
	return NULL;
}

uint32_t memregions_get_flags(phys_addr_t paddr)
{
	struct mem_region *r = memregions_find(paddr);

	return r ? r->flags : MR_F_UNKNOWN;
}

void memregions_split(phys_addr_t addr, struct mem_region **r1, struct mem_region **r2)
{
	*r1 = memregions_find(addr);
	assert(*r1);

	if ((*r1)->start == addr) {
		*r2 = *r1;
		*r1 = NULL;
		return;
	}

	*r2 = memregions_add(&(struct mem_region){
		.start = addr,
		.end = (*r1)->end,
		.flags = (*r1)->flags,
	});

	(*r1)->end = addr;
}

void memregions_add_dt_regions(size_t max_nr)
{
	struct dt_pbus_reg regs[max_nr];
	int nr_regs, i;

	nr_regs = dt_get_memory_params(regs, max_nr);
	assert(nr_regs > 0);

	for (i = 0; i < nr_regs; ++i) {
		memregions_add(&(struct mem_region){
			.start = regs[i].addr,
			.end = regs[i].addr + regs[i].size,
		});
	}
}

#ifdef CONFIG_EFI
/*
 * Add memory regions based on the EFI memory map. Also set a pointer to the
 * memory region which corresponds to the largest EFI_CONVENTIONAL_MEMORY
 * region, as that region is the largest free, continuous region, making it
 * a good choice for the memory allocator.
 */
void memregions_efi_init(struct efi_boot_memmap *mem_map,
			 struct mem_region **freemem)
{
	u8 *buffer = (u8 *)*mem_map->map;
	u64 freemem_pages = 0;

	*freemem = NULL;

	for (int i = 0; i < *mem_map->map_size; i += *mem_map->desc_size) {
		efi_memory_desc_t *d = (efi_memory_desc_t *)&buffer[i];
		struct mem_region r = {
			.start = d->phys_addr,
			.end = d->phys_addr + d->num_pages * EFI_PAGE_SIZE,
			.flags = 0,
		};

		switch (d->type) {
		case EFI_MEMORY_MAPPED_IO:
		case EFI_MEMORY_MAPPED_IO_PORT_SPACE:
			r.flags = MR_F_IO;
			break;
		case EFI_LOADER_CODE:
			r.flags = MR_F_CODE;
			break;
		case EFI_LOADER_DATA:
		case EFI_ACPI_RECLAIM_MEMORY:
			break;
		case EFI_PERSISTENT_MEMORY:
			r.flags = MR_F_PERSISTENT;
			break;
		case EFI_CONVENTIONAL_MEMORY:
			if (freemem_pages < d->num_pages) {
				freemem_pages = d->num_pages;
				*freemem = memregions_add(&r);
				continue;
			}
			break;
		default:
			r.flags = MR_F_RESERVED;
			break;
		}

		memregions_add(&r);
	}
}
#endif /* CONFIG_EFI */