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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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d358788f3f
Glen Turner reported that writing LFCR rather than the more traditional CRLF causes issues with some terminals. Since this aflicts many serial drivers, extract the common code to a library function (uart_console_write) and arrange for each driver to supply a "putchar" function. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
251 lines
6.4 KiB
C
251 lines
6.4 KiB
C
/*
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* Early serial console for 8250/16550 devices
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*
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* (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
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* Bjorn Helgaas <bjorn.helgaas@hp.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Based on the 8250.c serial driver, Copyright (C) 2001 Russell King,
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* and on early_printk.c by Andi Kleen.
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*
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* This is for use before the serial driver has initialized, in
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* particular, before the UARTs have been discovered and named.
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* Instead of specifying the console device as, e.g., "ttyS0",
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* we locate the device directly by its MMIO or I/O port address.
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*
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* The user can specify the device directly, e.g.,
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* console=uart,io,0x3f8,9600n8
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* console=uart,mmio,0xff5e0000,115200n8
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* or platform code can call early_uart_console_init() to set
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* the early UART device.
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*
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* After the normal serial driver starts, we try to locate the
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* matching ttyS device and start a console there.
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*/
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#include <linux/tty.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/serial_core.h>
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#include <linux/serial_reg.h>
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#include <linux/serial.h>
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#include <asm/io.h>
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#include <asm/serial.h>
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struct early_uart_device {
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struct uart_port port;
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char options[16]; /* e.g., 115200n8 */
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unsigned int baud;
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};
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static struct early_uart_device early_device __initdata;
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static int early_uart_registered __initdata;
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static unsigned int __init serial_in(struct uart_port *port, int offset)
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{
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if (port->iotype == UPIO_MEM)
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return readb(port->membase + offset);
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else
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return inb(port->iobase + offset);
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}
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static void __init serial_out(struct uart_port *port, int offset, int value)
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{
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if (port->iotype == UPIO_MEM)
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writeb(value, port->membase + offset);
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else
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outb(value, port->iobase + offset);
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}
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#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
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static void __init wait_for_xmitr(struct uart_port *port)
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{
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unsigned int status;
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for (;;) {
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status = serial_in(port, UART_LSR);
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if ((status & BOTH_EMPTY) == BOTH_EMPTY)
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return;
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cpu_relax();
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}
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}
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static void __init putc(struct uart_port *port, int c)
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{
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wait_for_xmitr(port);
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serial_out(port, UART_TX, c);
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}
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static void __init early_uart_write(struct console *console, const char *s, unsigned int count)
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{
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struct uart_port *port = &early_device.port;
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unsigned int ier;
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/* Save the IER and disable interrupts */
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ier = serial_in(port, UART_IER);
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serial_out(port, UART_IER, 0);
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uart_console_write(port, s, count, putc);
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/* Wait for transmitter to become empty and restore the IER */
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wait_for_xmitr(port);
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serial_out(port, UART_IER, ier);
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}
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static unsigned int __init probe_baud(struct uart_port *port)
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{
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unsigned char lcr, dll, dlm;
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unsigned int quot;
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lcr = serial_in(port, UART_LCR);
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serial_out(port, UART_LCR, lcr | UART_LCR_DLAB);
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dll = serial_in(port, UART_DLL);
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dlm = serial_in(port, UART_DLM);
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serial_out(port, UART_LCR, lcr);
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quot = (dlm << 8) | dll;
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return (port->uartclk / 16) / quot;
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}
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static void __init init_port(struct early_uart_device *device)
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{
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struct uart_port *port = &device->port;
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unsigned int divisor;
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unsigned char c;
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serial_out(port, UART_LCR, 0x3); /* 8n1 */
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serial_out(port, UART_IER, 0); /* no interrupt */
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serial_out(port, UART_FCR, 0); /* no fifo */
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serial_out(port, UART_MCR, 0x3); /* DTR + RTS */
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divisor = port->uartclk / (16 * device->baud);
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c = serial_in(port, UART_LCR);
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serial_out(port, UART_LCR, c | UART_LCR_DLAB);
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serial_out(port, UART_DLL, divisor & 0xff);
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serial_out(port, UART_DLM, (divisor >> 8) & 0xff);
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serial_out(port, UART_LCR, c & ~UART_LCR_DLAB);
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}
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static int __init parse_options(struct early_uart_device *device, char *options)
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{
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struct uart_port *port = &device->port;
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int mapsize = 64;
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int mmio, length;
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if (!options)
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return -ENODEV;
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port->uartclk = BASE_BAUD * 16;
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if (!strncmp(options, "mmio,", 5)) {
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port->iotype = UPIO_MEM;
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port->mapbase = simple_strtoul(options + 5, &options, 0);
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port->membase = ioremap(port->mapbase, mapsize);
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if (!port->membase) {
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printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
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__FUNCTION__, port->mapbase);
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return -ENOMEM;
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}
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mmio = 1;
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} else if (!strncmp(options, "io,", 3)) {
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port->iotype = UPIO_PORT;
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port->iobase = simple_strtoul(options + 3, &options, 0);
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mmio = 0;
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} else
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return -EINVAL;
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if ((options = strchr(options, ','))) {
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options++;
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device->baud = simple_strtoul(options, NULL, 0);
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length = min(strcspn(options, " "), sizeof(device->options));
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strncpy(device->options, options, length);
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} else {
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device->baud = probe_baud(port);
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snprintf(device->options, sizeof(device->options), "%u",
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device->baud);
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}
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printk(KERN_INFO "Early serial console at %s 0x%lx (options '%s')\n",
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mmio ? "MMIO" : "I/O port",
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mmio ? port->mapbase : (unsigned long) port->iobase,
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device->options);
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return 0;
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}
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static int __init early_uart_setup(struct console *console, char *options)
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{
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struct early_uart_device *device = &early_device;
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int err;
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if (device->port.membase || device->port.iobase)
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return 0;
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if ((err = parse_options(device, options)) < 0)
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return err;
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init_port(device);
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return 0;
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}
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static struct console early_uart_console __initdata = {
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.name = "uart",
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.write = early_uart_write,
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.setup = early_uart_setup,
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.flags = CON_PRINTBUFFER,
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.index = -1,
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};
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static int __init early_uart_console_init(void)
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{
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if (!early_uart_registered) {
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register_console(&early_uart_console);
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early_uart_registered = 1;
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}
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return 0;
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}
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console_initcall(early_uart_console_init);
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int __init early_serial_console_init(char *cmdline)
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{
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char *options;
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int err;
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options = strstr(cmdline, "console=uart,");
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if (!options)
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return -ENODEV;
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options = strchr(cmdline, ',') + 1;
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if ((err = early_uart_setup(NULL, options)) < 0)
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return err;
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return early_uart_console_init();
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}
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static int __init early_uart_console_switch(void)
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{
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struct early_uart_device *device = &early_device;
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struct uart_port *port = &device->port;
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int mmio, line;
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if (!(early_uart_console.flags & CON_ENABLED))
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return 0;
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/* Try to start the normal driver on a matching line. */
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mmio = (port->iotype == UPIO_MEM);
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line = serial8250_start_console(port, device->options);
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if (line < 0)
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printk("No ttyS device at %s 0x%lx for console\n",
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mmio ? "MMIO" : "I/O port",
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mmio ? port->mapbase :
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(unsigned long) port->iobase);
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unregister_console(&early_uart_console);
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if (mmio)
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iounmap(port->membase);
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return 0;
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}
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late_initcall(early_uart_console_switch);
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