kernel-ark/drivers/serial/8250_early.c
Russell King d358788f3f [SERIAL] kernel console should send CRLF not LFCR
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>
2006-03-20 20:00:09 +00:00

251 lines
6.4 KiB
C

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