drivers/tty/serial/8250/8250_early.c - kernel/msm-4.19 - 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.,
  *	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;

 unsigned int __weak __init serial8250_early_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;
 	}
 }

 void __weak __init serial8250_early_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 = serial8250_early_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);
 	serial8250_early_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 = serial8250_early_in(port, UART_IER);
 	serial8250_early_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);
 	serial8250_early_out(port, UART_IER, ier);
 }

 static unsigned int __init probe_baud(struct uart_port *port)
 {
 	unsigned char lcr, dll, dlm;
 	unsigned int quot;

 	lcr = serial8250_early_in(port, UART_LCR);
 	serial8250_early_out(port, UART_LCR, lcr | UART_LCR_DLAB);
 	dll = serial8250_early_in(port, UART_DLL);
 	dlm = serial8250_early_in(port, UART_DLM);
 	serial8250_early_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;

 	serial8250_early_out(port, UART_LCR, 0x3);	/* 8n1 */
 	serial8250_early_out(port, UART_IER, 0);	/* no interrupt */
 	serial8250_early_out(port, UART_FCR, 0);	/* no fifo */
 	serial8250_early_out(port, UART_MCR, 0x3);	/* DTR + RTS */

 	divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
 	c = serial8250_early_in(port, UART_LCR);
 	serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB);
 	serial8250_early_out(port, UART_DLL, divisor & 0xff);
 	serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
 	serial8250_early_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));
 		strlcpy(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);
	/*
	* 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;

	unsigned int __weak __init serial8250_early_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;
	}
	}

	void __weak __init serial8250_early_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 = serial8250_early_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);
	serial8250_early_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 = serial8250_early_in(port, UART_IER);
	serial8250_early_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);
	serial8250_early_out(port, UART_IER, ier);
	}

	static unsigned int __init probe_baud(struct uart_port *port)
	{
	unsigned char lcr, dll, dlm;
	unsigned int quot;

	lcr = serial8250_early_in(port, UART_LCR);
	serial8250_early_out(port, UART_LCR, lcr \| UART_LCR_DLAB);
	dll = serial8250_early_in(port, UART_DLL);
	dlm = serial8250_early_in(port, UART_DLM);
	serial8250_early_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;

	serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */
	serial8250_early_out(port, UART_IER, 0); /* no interrupt */
	serial8250_early_out(port, UART_FCR, 0); /* no fifo */
	serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */

	divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
	c = serial8250_early_in(port, UART_LCR);
	serial8250_early_out(port, UART_LCR, c \| UART_LCR_DLAB);
	serial8250_early_out(port, UART_DLL, divisor & 0xff);
	serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
	serial8250_early_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));
	strlcpy(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);