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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2026 Richard Qin */
/*
* uart.cc — 16550a UART driver (early console)
*
* Implements the early UART output mapping required by panic and kernel_main.
*/
#include <lume/console.h>
#include <lume/fdt.h>
#include <lume/vmm.h>
#include <lume/addr.h>
#include <arch/config.h>
static uint64 g_uart_pa = 0;
static uint64 g_uart_size = 0;
static bool g_runtime_mapping_ready = false;
static bool g_mmu_enabled = false;
extern "C" void console_set_mmu_enabled() {
g_mmu_enabled = true;
}
extern "C" void early_putc(char c) {
if (!g_uart_pa) return;
/*
* Before vmm_init() activates the final page table, UART MMIO is only
* reachable via the bootstrap fixed direct map from entry.S.
* After activation, switch to the runtime (possibly KASLR-slid) base.
*/
uint64 uart_va = 0;
if (g_runtime_mapping_ready) {
uart_va = pa_to_va(phys_addr(g_uart_pa)).raw;
} else if (!g_mmu_enabled) {
uart_va = g_uart_pa;
} else {
uart_va = boot_pa_to_va(phys_addr(g_uart_pa)).raw;
}
volatile auto* uart = reinterpret_cast<volatile uint8*>(uart_va);
*uart = static_cast<uint8>(c);
}
extern "C" void early_puts(const char* s) {
while (*s) early_putc(*s++);
}
void console_early_init(uint64 fdt_paddr) {
uint64 pa = 0;
uint64 size = 0;
FdtManager::early_scan_uart(fdt_paddr, &pa, &size);
if (pa != 0) {
g_uart_pa = pa;
if (size != 0) g_uart_size = size;
}
}
void console_init() {
/*
* Once vmm_init() activates the new page table, the 1GB identity map is dropped.
* The UART must be explicitly registered into the active page table.
*/
if (g_uart_pa != 0 && g_uart_size != 0) {
vmm_map_kernel_mmio(g_uart_pa, g_uart_size);
}
}
void console_use_runtime_mapping() {
g_runtime_mapping_ready = true;
}
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