[net-next-2.6.git] / drivers / serial / 8250_early.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.,
 *	earlycon=uart8250,io,0x3f8,9600n8
 *	earlycon=uart8250,mmio,0xff5e0000,115200n8
 * or
 *	console=uart8250,io,0x3f8,9600n8
 *	console=uart8250,mmio,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)
{
	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_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, 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, 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);
#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(port->mapbase, 64);
		if (!port->membase) {
			printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
				__FUNCTION__, port->mapbase);
			return -ENOMEM;
		}
#endif
		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 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;

	if ((err = parse_options(device, options)) < 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;
	if ((err = early_serial8250_setup(options)) < 0)
		return err;

	register_console(&early_serial8250_console);

	return 0;
}

int __init 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);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Early serial console for 8250/16550 devices
	3	*
	4	* (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
	5	* Bjorn Helgaas <bjorn.helgaas@hp.com>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	* Based on the 8250.c serial driver, Copyright (C) 2001 Russell King,
	12	* and on early_printk.c by Andi Kleen.
	13	*
	14	* This is for use before the serial driver has initialized, in
	15	* particular, before the UARTs have been discovered and named.
	16	* Instead of specifying the console device as, e.g., "ttyS0",
	17	* we locate the device directly by its MMIO or I/O port address.
	18	*
	19	* The user can specify the device directly, e.g.,
18a8bd94 YL	20	* earlycon=uart8250,io,0x3f8,9600n8
	21	* earlycon=uart8250,mmio,0xff5e0000,115200n8
	22	* or
	23	* console=uart8250,io,0x3f8,9600n8
	24	* console=uart8250,mmio,0xff5e0000,115200n8
1da177e4 LT	25	*/
	26
	27	#include <linux/tty.h>
	28	#include <linux/init.h>
	29	#include <linux/console.h>
	30	#include <linux/serial_core.h>
	31	#include <linux/serial_reg.h>
	32	#include <linux/serial.h>
18a8bd94	33	#include <linux/serial_8250.h>
1da177e4 LT	34	#include <asm/io.h>
1da177e4 LT	35	#include <asm/serial.h>
18a8bd94 YL	36	#ifdef CONFIG_FIX_EARLYCON_MEM
	37	#include <asm/pgtable.h>
	38	#include <asm/fixmap.h>
	39	#endif
1da177e4	40
18a8bd94	41	struct early_serial8250_device {
1da177e4 LT	42	struct uart_port port;
	43	char options[16]; /* e.g., 115200n8 */
	44	unsigned int baud;
	45	};
	46
18a8bd94	47	static struct early_serial8250_device early_device;
1da177e4 LT	48
	49	static unsigned int __init serial_in(struct uart_port *port, int offset)
	50	{
	51	if (port->iotype == UPIO_MEM)
	52	return readb(port->membase + offset);
	53	else
	54	return inb(port->iobase + offset);
	55	}
	56
	57	static void __init serial_out(struct uart_port *port, int offset, int value)
	58	{
	59	if (port->iotype == UPIO_MEM)
	60	writeb(value, port->membase + offset);
	61	else
	62	outb(value, port->iobase + offset);
	63	}
	64
	65	#define BOTH_EMPTY (UART_LSR_TEMT \| UART_LSR_THRE)
	66
	67	static void __init wait_for_xmitr(struct uart_port *port)
	68	{
	69	unsigned int status;
	70
	71	for (;;) {
	72	status = serial_in(port, UART_LSR);
	73	if ((status & BOTH_EMPTY) == BOTH_EMPTY)
	74	return;
	75	cpu_relax();
	76	}
	77	}
	78
d358788f	79	static void __init putc(struct uart_port *port, int c)
1da177e4 LT	80	{
	81	wait_for_xmitr(port);
	82	serial_out(port, UART_TX, c);
	83	}
	84
18a8bd94	85	static void __init early_serial8250_write(struct console console, const char s, unsigned int count)
1da177e4 LT	86	{
	87	struct uart_port *port = &early_device.port;
	88	unsigned int ier;
	89
	90	/* Save the IER and disable interrupts */
	91	ier = serial_in(port, UART_IER);
	92	serial_out(port, UART_IER, 0);
	93
d358788f	94	uart_console_write(port, s, count, putc);
1da177e4 LT	95
	96	/* Wait for transmitter to become empty and restore the IER */
	97	wait_for_xmitr(port);
	98	serial_out(port, UART_IER, ier);
	99	}
	100
	101	static unsigned int __init probe_baud(struct uart_port *port)
	102	{
	103	unsigned char lcr, dll, dlm;
	104	unsigned int quot;
	105
	106	lcr = serial_in(port, UART_LCR);
	107	serial_out(port, UART_LCR, lcr \| UART_LCR_DLAB);
	108	dll = serial_in(port, UART_DLL);
	109	dlm = serial_in(port, UART_DLM);
	110	serial_out(port, UART_LCR, lcr);
	111
	112	quot = (dlm << 8) \| dll;
	113	return (port->uartclk / 16) / quot;
	114	}
	115
18a8bd94	116	static void __init init_port(struct early_serial8250_device *device)
1da177e4 LT	117	{
	118	struct uart_port *port = &device->port;
	119	unsigned int divisor;
	120	unsigned char c;
	121
	122	serial_out(port, UART_LCR, 0x3); /* 8n1 */
	123	serial_out(port, UART_IER, 0); /* no interrupt */
	124	serial_out(port, UART_FCR, 0); /* no fifo */
	125	serial_out(port, UART_MCR, 0x3); /* DTR + RTS */
	126
	127	divisor = port->uartclk / (16 * device->baud);
	128	c = serial_in(port, UART_LCR);
	129	serial_out(port, UART_LCR, c \| UART_LCR_DLAB);
	130	serial_out(port, UART_DLL, divisor & 0xff);
	131	serial_out(port, UART_DLM, (divisor >> 8) & 0xff);
	132	serial_out(port, UART_LCR, c & ~UART_LCR_DLAB);
	133	}
	134
18a8bd94	135	static int __init parse_options(struct early_serial8250_device device, char options)
1da177e4 LT	136	{
1da177e4 LT	137	struct uart_port *port = &device->port;
1da177e4 LT	138	int mmio, length;
	139
	140	if (!options)
	141	return -ENODEV;
	142
	143	port->uartclk = BASE_BAUD * 16;
	144	if (!strncmp(options, "mmio,", 5)) {
	145	port->iotype = UPIO_MEM;
	146	port->mapbase = simple_strtoul(options + 5, &options, 0);
18a8bd94 YL	147	#ifdef CONFIG_FIX_EARLYCON_MEM
	148	set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, port->mapbase & PAGE_MASK);
	149	port->membase = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
	150	port->membase += port->mapbase & ~PAGE_MASK;
	151	#else
	152	port->membase = ioremap(port->mapbase, 64);
1da177e4 LT	153	if (!port->membase) {
	154	printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
	155	__FUNCTION__, port->mapbase);
	156	return -ENOMEM;
	157	}
18a8bd94	158	#endif
1da177e4 LT	159	mmio = 1;
	160	} else if (!strncmp(options, "io,", 3)) {
	161	port->iotype = UPIO_PORT;
	162	port->iobase = simple_strtoul(options + 3, &options, 0);
	163	mmio = 0;
	164	} else
	165	return -EINVAL;
	166
	167	if ((options = strchr(options, ','))) {
	168	options++;
b2281abf	169	device->baud = simple_strtoul(options, NULL, 0);
1da177e4 LT	170	length = min(strcspn(options, " "), sizeof(device->options));
	171	strncpy(device->options, options, length);
	172	} else {
	173	device->baud = probe_baud(port);
	174	snprintf(device->options, sizeof(device->options), "%u",
	175	device->baud);
	176	}
	177
	178	printk(KERN_INFO "Early serial console at %s 0x%lx (options '%s')\n",
	179	mmio ? "MMIO" : "I/O port",
	180	mmio ? port->mapbase : (unsigned long) port->iobase,
	181	device->options);
	182	return 0;
	183	}
	184
18a8bd94 YL	185	static struct console early_serial8250_console __initdata = {
	186	.name = "uart",
	187	.write = early_serial8250_write,
	188	.flags = CON_PRINTBUFFER \| CON_BOOT,
	189	.index = -1,
	190	};
	191
	192	static int __init early_serial8250_setup(char *options)
1da177e4	193	{
18a8bd94	194	struct early_serial8250_device *device = &early_device;
1da177e4 LT	195	int err;
	196
	197	if (device->port.membase \|\| device->port.iobase)
	198	return 0;
	199
	200	if ((err = parse_options(device, options)) < 0)
	201	return err;
	202
	203	init_port(device);
	204	return 0;
	205	}
	206
18a8bd94	207	int __init setup_early_serial8250_console(char *cmdline)
1da177e4 LT	208	{
	209	char *options;
	210	int err;
	211
18a8bd94 YL	212	options = strstr(cmdline, "uart8250,");
	213	if (!options) {
	214	options = strstr(cmdline, "uart,");
	215	if (!options)
	216	return 0;
	217	}
1da177e4 LT	218
1da177e4 LT	219	options = strchr(cmdline, ',') + 1;
18a8bd94	220	if ((err = early_serial8250_setup(options)) < 0)
1da177e4	221	return err;
18a8bd94 YL	222
	223	register_console(&early_serial8250_console);
	224
	225	return 0;
1da177e4 LT	226	}
1da177e4 LT	227
18a8bd94	228	int __init serial8250_find_port_for_earlycon(void)
1da177e4	229	{
18a8bd94	230	struct early_serial8250_device *device = &early_device;
1da177e4	231	struct uart_port *port = &device->port;
18a8bd94 YL	232	int line;
18a8bd94 YL	233	int ret;
1da177e4	234
18a8bd94 YL	235	if (!device->port.membase && !device->port.iobase)
18a8bd94 YL	236	return -ENODEV;
1da177e4	237
18a8bd94	238	line = serial8250_find_port(port);
1da177e4	239	if (line < 0)
18a8bd94	240	return -ENODEV;
1da177e4	241
18a8bd94 YL	242	ret = update_console_cmdline("uart", 8250,
	243	"ttyS", line, device->options);
	244	if (ret < 0)
	245	ret = update_console_cmdline("uart", 0,
	246	"ttyS", line, device->options);
1da177e4	247
18a8bd94	248	return ret;
1da177e4	249	}
18a8bd94 YL	250
18a8bd94 YL	251	early_param("earlycon", setup_early_serial8250_console);