55 строки
1.2 KiB
C
55 строки
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* 8250/16550-type serial ports prom_putchar()
|
|
*
|
|
* Copyright (C) 2010 Yoichi Yuasa <yuasa@linux-mips.org>
|
|
*/
|
|
#include <linux/io.h>
|
|
#include <linux/serial_core.h>
|
|
#include <linux/serial_reg.h>
|
|
#include <asm/setup.h>
|
|
|
|
static void __iomem *serial8250_base;
|
|
static unsigned int serial8250_reg_shift;
|
|
static unsigned int serial8250_tx_timeout;
|
|
|
|
void setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift,
|
|
unsigned int timeout)
|
|
{
|
|
serial8250_base = (void __iomem *)base;
|
|
serial8250_reg_shift = reg_shift;
|
|
serial8250_tx_timeout = timeout;
|
|
}
|
|
|
|
static inline u8 serial_in(int offset)
|
|
{
|
|
return readb(serial8250_base + (offset << serial8250_reg_shift));
|
|
}
|
|
|
|
static inline void serial_out(int offset, char value)
|
|
{
|
|
writeb(value, serial8250_base + (offset << serial8250_reg_shift));
|
|
}
|
|
|
|
void prom_putchar(char c)
|
|
{
|
|
unsigned int timeout;
|
|
int status, bits;
|
|
|
|
if (!serial8250_base)
|
|
return;
|
|
|
|
timeout = serial8250_tx_timeout;
|
|
bits = UART_LSR_TEMT | UART_LSR_THRE;
|
|
|
|
do {
|
|
status = serial_in(UART_LSR);
|
|
|
|
if (--timeout == 0)
|
|
break;
|
|
} while ((status & bits) != bits);
|
|
|
|
if (timeout)
|
|
serial_out(UART_TX, c);
|
|
}
|