1 files changed, 287 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250_early.c b/drivers/tty/serial/8250_early.c
new file mode 100644
index 00000000000..eaafb98debe
--- /dev/null
+++ b/drivers/tty/serial/8250_early.c
@@ -0,0 +1,287 @@
+/*
+ * 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);