#include <zinnia/alloc.h>
#include <zinnia/cmdline.h>
#include <zinnia/compiler.h>
#include <zinnia/percpu.h>
#include <zinnia/utils.h>
#include <arch/percpu.h>
#include <stdatomic.h>

extern uint8_t __ld_percpu_start[];
extern uint8_t __ld_percpu_end[];

static _Atomic(size_t) num_cpus = 1;

static size_t max_cpus = SIZE_MAX;
static void smp_option(uintptr_t value) {
    max_cpus = value;
}
CMDLINE_OPTION("smp", "Maximum number of CPUs to use", smp_option);

[[__used, __section(".percpu.init")]]
struct percpu percpu_bsp = {
    .self = &percpu_bsp,
    .id = 0,
    .online = false,
};

struct percpu* percpu_new() {
    const size_t size = __ld_percpu_end - __ld_percpu_start;
    const size_t num_pages = ALIGN_UP(size, arch_mem_page_size()) / arch_mem_page_size();

    // TODO: Map pages past the end of the kernel.
    // TODO: Document how allocations work.

    phys_t mem;
    if (mem_phys_alloc(num_pages, 0, &mem))
        return nullptr;

    struct percpu* cpu = HHDM_PTR(mem);
    cpu->self = cpu;
    cpu->id = atomic_fetch_add_explicit(&num_cpus, 1, memory_order_relaxed);
    cpu->online = false;
    return cpu;
}

size_t percpu_max_cpus() {
    return max_cpus;
}

struct percpu* percpu_get() {
    return arch_percpu_get();
}

void percpu_bsp_init() {
    arch_percpu_bsp_init();
}

void percpu_init(struct boot_info*) {
    arch_percpu_init();
}
INIT_TASK(percpu_stage, "core.percpu", percpu_init);
INIT_DEPENDS(percpu_stage, mem_stage);