[mirror_ubuntu-zesty-kernel.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.,
 *	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);
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.,
	20	* console=uart,io,0x3f8,9600n8
	21	* console=uart,mmio,0xff5e0000,115200n8
	22	* or platform code can call early_uart_console_init() to set
	23	* the early UART device.
	24	*
	25	* After the normal serial driver starts, we try to locate the
	26	* matching ttyS device and start a console there.
	27	*/
	28
	29	#include <linux/tty.h>
	30	#include <linux/init.h>
	31	#include <linux/console.h>
	32	#include <linux/serial_core.h>
	33	#include <linux/serial_reg.h>
	34	#include <linux/serial.h>
	35	#include <asm/io.h>
	36	#include <asm/serial.h>
	37
	38	struct early_uart_device {
	39	struct uart_port port;
	40	char options[16]; /* e.g., 115200n8 */
	41	unsigned int baud;
	42	};
	43
	44	static struct early_uart_device early_device __initdata;
	45	static int early_uart_registered __initdata;
	46
	47	static unsigned int __init serial_in(struct uart_port *port, int offset)
	48	{
	49	if (port->iotype == UPIO_MEM)
	50	return readb(port->membase + offset);
	51	else
	52	return inb(port->iobase + offset);
	53	}
	54
	55	static void __init serial_out(struct uart_port *port, int offset, int value)
	56	{
	57	if (port->iotype == UPIO_MEM)
	58	writeb(value, port->membase + offset);
	59	else
	60	outb(value, port->iobase + offset);
	61	}
	62
	63	#define BOTH_EMPTY (UART_LSR_TEMT \| UART_LSR_THRE)
	64
65	static void __init wait_for_xmitr(struct uart_port *port)
66	{
67	unsigned int status;
68
69	for (;;) {
70	status = serial_in(port, UART_LSR);
71	if ((status & BOTH_EMPTY) == BOTH_EMPTY)
72	return;
73	cpu_relax();
74	}
75	}
76
d358788f	77	static void __init putc(struct uart_port *port, int c)
1da177e4 LT	78	{
	79	wait_for_xmitr(port);
	80	serial_out(port, UART_TX, c);
	81	}
	82
	83	static void __init early_uart_write(struct console console, const char s, unsigned int count)
	84	{
	85	struct uart_port *port = &early_device.port;
	86	unsigned int ier;
	87
	88	/* Save the IER and disable interrupts */
	89	ier = serial_in(port, UART_IER);
	90	serial_out(port, UART_IER, 0);
	91
d358788f	92	uart_console_write(port, s, count, putc);
1da177e4 LT	93
	94	/* Wait for transmitter to become empty and restore the IER */
	95	wait_for_xmitr(port);
	96	serial_out(port, UART_IER, ier);
	97	}
	98
	99	static unsigned int __init probe_baud(struct uart_port *port)
	100	{
	101	unsigned char lcr, dll, dlm;
	102	unsigned int quot;
	103
	104	lcr = serial_in(port, UART_LCR);
	105	serial_out(port, UART_LCR, lcr \| UART_LCR_DLAB);
	106	dll = serial_in(port, UART_DLL);
	107	dlm = serial_in(port, UART_DLM);
	108	serial_out(port, UART_LCR, lcr);
	109
	110	quot = (dlm << 8) \| dll;
	111	return (port->uartclk / 16) / quot;
	112	}
	113
	114	static void __init init_port(struct early_uart_device *device)
	115	{
	116	struct uart_port *port = &device->port;
	117	unsigned int divisor;
	118	unsigned char c;
	119
	120	serial_out(port, UART_LCR, 0x3); /* 8n1 */
	121	serial_out(port, UART_IER, 0); /* no interrupt */
	122	serial_out(port, UART_FCR, 0); /* no fifo */
	123	serial_out(port, UART_MCR, 0x3); /* DTR + RTS */
	124
	125	divisor = port->uartclk / (16 * device->baud);
	126	c = serial_in(port, UART_LCR);
	127	serial_out(port, UART_LCR, c \| UART_LCR_DLAB);
	128	serial_out(port, UART_DLL, divisor & 0xff);
	129	serial_out(port, UART_DLM, (divisor >> 8) & 0xff);
	130	serial_out(port, UART_LCR, c & ~UART_LCR_DLAB);
	131	}
	132
	133	static int __init parse_options(struct early_uart_device device, char options)
	134	{
	135	struct uart_port *port = &device->port;
	136	int mapsize = 64;
	137	int mmio, length;
	138
	139	if (!options)
	140	return -ENODEV;
	141
	142	port->uartclk = BASE_BAUD * 16;
	143	if (!strncmp(options, "mmio,", 5)) {
	144	port->iotype = UPIO_MEM;
	145	port->mapbase = simple_strtoul(options + 5, &options, 0);
	146	port->membase = ioremap(port->mapbase, mapsize);
	147	if (!port->membase) {
	148	printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
	149	__FUNCTION__, port->mapbase);
	150	return -ENOMEM;
	151	}
	152	mmio = 1;
	153	} else if (!strncmp(options, "io,", 3)) {
	154	port->iotype = UPIO_PORT;
	155	port->iobase = simple_strtoul(options + 3, &options, 0);
	156	mmio = 0;
157	} else
158	return -EINVAL;
159
160	if ((options = strchr(options, ','))) {
161	options++;
b2281abf	162	device->baud = simple_strtoul(options, NULL, 0);
1da177e4 LT	163	length = min(strcspn(options, " "), sizeof(device->options));
	164	strncpy(device->options, options, length);
	165	} else {
	166	device->baud = probe_baud(port);
	167	snprintf(device->options, sizeof(device->options), "%u",
	168	device->baud);
	169	}
	170
	171	printk(KERN_INFO "Early serial console at %s 0x%lx (options '%s')\n",
	172	mmio ? "MMIO" : "I/O port",
	173	mmio ? port->mapbase : (unsigned long) port->iobase,
	174	device->options);
	175	return 0;
	176	}
	177
	178	static int __init early_uart_setup(struct console console, char options)
	179	{
	180	struct early_uart_device *device = &early_device;
	181	int err;
	182
	183	if (device->port.membase \|\| device->port.iobase)
	184	return 0;
	185
	186	if ((err = parse_options(device, options)) < 0)
	187	return err;
	188
	189	init_port(device);
	190	return 0;
	191	}
	192
	193	static struct console early_uart_console __initdata = {
	194	.name = "uart",
	195	.write = early_uart_write,
	196	.setup = early_uart_setup,
	197	.flags = CON_PRINTBUFFER,
	198	.index = -1,
	199	};
	200
	201	static int __init early_uart_console_init(void)
	202	{
	203	if (!early_uart_registered) {
	204	register_console(&early_uart_console);
	205	early_uart_registered = 1;
	206	}
	207	return 0;
	208	}
	209	console_initcall(early_uart_console_init);
	210
	211	int __init early_serial_console_init(char *cmdline)
	212	{
	213	char *options;
	214	int err;
	215
	216	options = strstr(cmdline, "console=uart,");
	217	if (!options)
	218	return -ENODEV;
	219
	220	options = strchr(cmdline, ',') + 1;
	221	if ((err = early_uart_setup(NULL, options)) < 0)
	222	return err;
	223	return early_uart_console_init();
	224	}
	225
	226	static int __init early_uart_console_switch(void)
227	{
228	struct early_uart_device *device = &early_device;
229	struct uart_port *port = &device->port;
230	int mmio, line;
231
232	if (!(early_uart_console.flags & CON_ENABLED))
233	return 0;
234
235	/* Try to start the normal driver on a matching line. */
236	mmio = (port->iotype == UPIO_MEM);
237	line = serial8250_start_console(port, device->options);
238	if (line < 0)
239	printk("No ttyS device at %s 0x%lx for console\n",
240	mmio ? "MMIO" : "I/O port",
241	mmio ? port->mapbase :
242	(unsigned long) port->iobase);
243
244	unregister_console(&early_uart_console);
245	if (mmio)
246	iounmap(port->membase);
247
248	return 0;
249	}
250	late_initcall(early_uart_console_switch);