drivers/serial/8250_early.c - kernel/msm - Gitiles

 /*
  * 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);
	/*
	* 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);