// SPDX-License-Identifier: GPL-2.0
/*
 * printf.c:  Internal prom library printf facility.
 *
 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
 * Copyright (c) 2002 Pete Zaitcev (zaitcev@yahoo.com)
 *
 * We used to warn all over the code: DO NOT USE prom_printf(),
 * and yet people do. Anton's banking code was outputting banks
 * with prom_printf for most of the 2.4 lifetime. Since an effective
 * stick is not available, we deployed a carrot: an early printk
 * through PROM by means of -p boot option. This ought to fix it.
 * USE printk; if you need, deploy -p.
 */

#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/spinlock.h>

#include <asm/openprom.h>
#include <asm/oplib.h>

#define CONSOLE_WRITE_BUF_SIZE  1024

static char ppbuf[1024];
static char console_write_buf[CONSOLE_WRITE_BUF_SIZE];
static DEFINE_RAW_SPINLOCK(console_write_lock);

void notrace prom_write(const char *buf, unsigned int n)
{
        unsigned int dest_len;
        unsigned long flags;
        char *dest;

        dest = console_write_buf;
        raw_spin_lock_irqsave(&console_write_lock, flags);

        dest_len = 0;
        while (n-- != 0) {
                char ch = *buf++;
                if (ch == '\n') {
                        *dest++ = '\r';
                        dest_len++;
                }
                *dest++ = ch;
                dest_len++;
                if (dest_len >= CONSOLE_WRITE_BUF_SIZE - 1) {
                        prom_console_write_buf(console_write_buf, dest_len);
                        dest = console_write_buf;
                        dest_len = 0;
                }
        }
        if (dest_len)
                prom_console_write_buf(console_write_buf, dest_len);

        raw_spin_unlock_irqrestore(&console_write_lock, flags);
}

void notrace prom_printf(const char *fmt, ...)
{
        va_list args;
        int i;

        va_start(args, fmt);
        i = vscnprintf(ppbuf, sizeof(ppbuf), fmt, args);
        va_end(args);

        prom_write(ppbuf, i);
}