// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 *  Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org>
 */

#include <linux/io.h>
#include <linux/serial_reg.h>

#include <asm/addrspace.h>
#include <asm/setup.h>

#ifdef CONFIG_SOC_RT288X
#define EARLY_UART_BASE         0x300c00
#define CHIPID_BASE             0x300004
#elif defined(CONFIG_SOC_MT7621)
#define EARLY_UART_BASE         0x1E000c00
#define CHIPID_BASE             0x1E000004
#else
#define EARLY_UART_BASE         0x10000c00
#define CHIPID_BASE             0x10000004
#endif

#define MT7628_CHIP_NAME1       0x20203832

#define UART_REG_TX             0x04
#define UART_REG_LCR            0x0c
#define UART_REG_LSR            0x14
#define UART_REG_LSR_RT2880     0x1c

static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE);
static __iomem void *chipid_membase = (__iomem void *) KSEG1ADDR(CHIPID_BASE);
static int init_complete;

static inline void uart_w32(u32 val, unsigned reg)
{
        __raw_writel(val, uart_membase + reg);
}

static inline u32 uart_r32(unsigned reg)
{
        return __raw_readl(uart_membase + reg);
}

static inline int soc_is_mt7628(void)
{
        return IS_ENABLED(CONFIG_SOC_MT7620) &&
                (__raw_readl(chipid_membase) == MT7628_CHIP_NAME1);
}

static void find_uart_base(void)
{
        int i;

        if (!soc_is_mt7628())
                return;

        for (i = 0; i < 3; i++) {
                u32 reg = uart_r32(UART_REG_LCR + (0x100 * i));

                if (!reg)
                        continue;

                uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE +
                                                          (0x100 * i));
                break;
        }
}

void prom_putchar(char ch)
{
        if (!init_complete) {
                find_uart_base();
                init_complete = 1;
        }

        if (IS_ENABLED(CONFIG_SOC_MT7621) || soc_is_mt7628()) {
                uart_w32((unsigned char)ch, UART_TX);
                while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0)
                        ;
        } else {
                while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0)
                        ;
                uart_w32((unsigned char)ch, UART_REG_TX);
                while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0)
                        ;
        }
}