summaryrefslogtreecommitdiffstats
path: root/drivers/tty/serial/earlycon.c
blob: 5131b5ee616434830344c6afe05c23ad5ae1b7cc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
/*
 * Copyright (C) 2014 Linaro Ltd.
 * Author: Rob Herring <robh@kernel.org>
 *
 * Based on 8250 earlycon:
 * (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.
 */
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/serial_core.h>
#include <linux/sizes.h>
#include <linux/mod_devicetable.h>

#ifdef CONFIG_FIX_EARLYCON_MEM
#include <asm/fixmap.h>
#endif

#include <asm/serial.h>

static struct console early_con = {
	.name =		"earlycon",
	.flags =	CON_PRINTBUFFER | CON_BOOT,
	.index =	-1,
};

static struct earlycon_device early_console_dev = {
	.con = &early_con,
};

static const struct of_device_id __earlycon_of_table_sentinel
	__used __section(__earlycon_of_table_end);

static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
{
	void __iomem *base;
#ifdef CONFIG_FIX_EARLYCON_MEM
	set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
	base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
	base += paddr & ~PAGE_MASK;
#else
	base = ioremap(paddr, size);
#endif
	if (!base)
		pr_err("%s: Couldn't map 0x%llx\n", __func__,
		       (unsigned long long)paddr);

	return base;
}

static int __init parse_options(struct earlycon_device *device,
				char *options)
{
	struct uart_port *port = &device->port;
	int mmio, mmio32, length;
	unsigned long addr;

	if (!options)
		return -ENODEV;

	mmio = !strncmp(options, "mmio,", 5);
	mmio32 = !strncmp(options, "mmio32,", 7);
	if (mmio || mmio32) {
		port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32);
		options += mmio ? 5 : 7;
		addr = simple_strtoul(options, NULL, 0);
		port->mapbase = addr;
		if (mmio32)
			port->regshift = 2;
	} else if (!strncmp(options, "io,", 3)) {
		port->iotype = UPIO_PORT;
		options += 3;
		addr = simple_strtoul(options, NULL, 0);
		port->iobase = addr;
		mmio = 0;
	} else if (!strncmp(options, "0x", 2)) {
		port->iotype = UPIO_MEM;
		addr = simple_strtoul(options, NULL, 0);
		port->mapbase = addr;
	} else {
		return -EINVAL;
	}

	port->uartclk = BASE_BAUD * 16;

	options = strchr(options, ',');
	if (options) {
		options++;
		device->baud = simple_strtoul(options, NULL, 0);
		length = min(strcspn(options, " ") + 1,
			     (size_t)(sizeof(device->options)));
		strlcpy(device->options, options, length);
	}

	if (mmio || mmio32)
		pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
			mmio32 ? "32" : "",
			(unsigned long long)port->mapbase,
			device->options);
	else
		pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
			port->iobase,
			device->options);

	return 0;
}

int __init setup_earlycon(char *buf, const char *match,
			  int (*setup)(struct earlycon_device *, const char *))
{
	int err;
	size_t len;
	struct uart_port *port = &early_console_dev.port;

	if (!buf || !match || !setup)
		return 0;

	len = strlen(match);
	if (strncmp(buf, match, len))
		return 0;
	if (buf[len] && (buf[len] != ','))
		return 0;

	buf += len + 1;

	err = parse_options(&early_console_dev, buf);
	/* On parsing error, pass the options buf to the setup function */
	if (!err)
		buf = NULL;

	if (port->mapbase)
		port->membase = earlycon_map(port->mapbase, 64);

	early_console_dev.con->data = &early_console_dev;
	err = setup(&early_console_dev, buf);
	if (err < 0)
		return err;
	if (!early_console_dev.con->write)
		return -ENODEV;

	register_console(early_console_dev.con);
	return 0;
}

int __init of_setup_earlycon(unsigned long addr,
			     int (*setup)(struct earlycon_device *, const char *))
{
	int err;
	struct uart_port *port = &early_console_dev.port;

	port->iotype = UPIO_MEM;
	port->mapbase = addr;
	port->uartclk = BASE_BAUD * 16;
	port->membase = earlycon_map(addr, SZ_4K);

	early_console_dev.con->data = &early_console_dev;
	err = setup(&early_console_dev, NULL);
	if (err < 0)
		return err;
	if (!early_console_dev.con->write)
		return -ENODEV;


	register_console(early_console_dev.con);
	return 0;
}