Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 | /*
* 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.,
* earlycon=uart8250,io,0x3f8,9600n8
* earlycon=uart8250,mmio,0xff5e0000,115200n8
* earlycon=uart8250,mmio32,0xff5e0000,115200n8
* or
* console=uart8250,io,0x3f8,9600n8
* console=uart8250,mmio,0xff5e0000,115200n8
* console=uart8250,mmio32,0xff5e0000,115200n8
*/
#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 <linux/serial_8250.h>
#include <asm/io.h>
#include <asm/serial.h>
#ifdef CONFIG_FIX_EARLYCON_MEM
#include <asm/pgtable.h>
#include <asm/fixmap.h>
#endif
struct early_serial8250_device {
struct uart_port port;
char options[16]; /* e.g., 115200n8 */
unsigned int baud;
};
static struct early_serial8250_device early_device;
static unsigned int __init serial_in(struct uart_port *port, int offset)
{
switch (port->iotype) {
case UPIO_MEM:
return readb(port->membase + offset);
case UPIO_MEM32:
return readl(port->membase + (offset << 2));
case UPIO_PORT:
return inb(port->iobase + offset);
default:
return 0;
}
}
static void __init serial_out(struct uart_port *port, int offset, int value)
{
switch (port->iotype) {
case UPIO_MEM:
writeb(value, port->membase + offset);
break;
case UPIO_MEM32:
writel(value, port->membase + (offset << 2));
break;
case UPIO_PORT:
outb(value, port->iobase + offset);
break;
}
}
#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 serial_putc(struct uart_port *port, int c)
{
wait_for_xmitr(port);
serial_out(port, UART_TX, c);
}
static void __init early_serial8250_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, serial_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_serial8250_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_serial8250_device *device,
char *options)
{
struct uart_port *port = &device->port;
int mmio, mmio32, length;
if (!options)
return -ENODEV;
port->uartclk = BASE_BAUD * 16;
mmio = !strncmp(options, "mmio,", 5);
mmio32 = !strncmp(options, "mmio32,", 7);
if (mmio || mmio32) {
port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32);
port->mapbase = simple_strtoul(options + (mmio ? 5 : 7),
&options, 0);
if (mmio32)
port->regshift = 2;
#ifdef CONFIG_FIX_EARLYCON_MEM
set_fixmap_nocache(FIX_EARLYCON_MEM_BASE,
port->mapbase & PAGE_MASK);
port->membase =
(void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
port->membase += port->mapbase & ~PAGE_MASK;
#else
port->membase = ioremap_nocache(port->mapbase, 64);
if (!port->membase) {
printk(KERN_ERR "%s: Couldn't ioremap 0x%llx\n",
__func__,
(unsigned long long) port->mapbase);
return -ENOMEM;
}
#endif
} else if (!strncmp(options, "io,", 3)) {
port->iotype = UPIO_PORT;
port->iobase = simple_strtoul(options + 3, &options, 0);
mmio = 0;
} else
return -EINVAL;
options = strchr(options, ',');
if (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);
}
if (mmio || mmio32)
printk(KERN_INFO
"Early serial console at MMIO%s 0x%llx (options '%s')\n",
mmio32 ? "32" : "",
(unsigned long long)port->mapbase,
device->options);
else
printk(KERN_INFO
"Early serial console at I/O port 0x%lx (options '%s')\n",
port->iobase,
device->options);
return 0;
}
static struct console early_serial8250_console __initdata = {
.name = "uart",
.write = early_serial8250_write,
.flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1,
};
static int __init early_serial8250_setup(char *options)
{
struct early_serial8250_device *device = &early_device;
int err;
if (device->port.membase || device->port.iobase)
return 0;
err = parse_options(device, options);
if (err < 0)
return err;
init_port(device);
return 0;
}
int __init setup_early_serial8250_console(char *cmdline)
{
char *options;
int err;
options = strstr(cmdline, "uart8250,");
if (!options) {
options = strstr(cmdline, "uart,");
if (!options)
return 0;
}
options = strchr(cmdline, ',') + 1;
err = early_serial8250_setup(options);
if (err < 0)
return err;
register_console(&early_serial8250_console);
return 0;
}
int serial8250_find_port_for_earlycon(void)
{
struct early_serial8250_device *device = &early_device;
struct uart_port *port = &device->port;
int line;
int ret;
if (!device->port.membase && !device->port.iobase)
return -ENODEV;
line = serial8250_find_port(port);
if (line < 0)
return -ENODEV;
ret = update_console_cmdline("uart", 8250,
"ttyS", line, device->options);
if (ret < 0)
ret = update_console_cmdline("uart", 0,
"ttyS", line, device->options);
return ret;
}
early_param("earlycon", setup_early_serial8250_console);
|