xref: /linux/drivers/tty/serial/earlycon.c (revision 9e9f60108423f18a99c9cc93ef7f23490ecc709b)
1 /*
2  * Copyright (C) 2014 Linaro Ltd.
3  * Author: Rob Herring <robh@kernel.org>
4  *
5  * Based on 8250 earlycon:
6  * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
7  *	Bjorn Helgaas <bjorn.helgaas@hp.com>
8  *
9  * This program is free software: you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13 #include <linux/console.h>
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/io.h>
17 #include <linux/serial_core.h>
18 #include <linux/sizes.h>
19 #include <linux/mod_devicetable.h>
20 
21 #ifdef CONFIG_FIX_EARLYCON_MEM
22 #include <asm/fixmap.h>
23 #endif
24 
25 #include <asm/serial.h>
26 
27 static struct console early_con = {
28 	.name =		"uart", /* 8250 console switch requires this name */
29 	.flags =	CON_PRINTBUFFER | CON_BOOT,
30 	.index =	-1,
31 };
32 
33 static struct earlycon_device early_console_dev = {
34 	.con = &early_con,
35 };
36 
37 static const struct of_device_id __earlycon_of_table_sentinel
38 	__used __section(__earlycon_of_table_end);
39 
40 static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
41 {
42 	void __iomem *base;
43 #ifdef CONFIG_FIX_EARLYCON_MEM
44 	set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
45 	base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
46 	base += paddr & ~PAGE_MASK;
47 #else
48 	base = ioremap(paddr, size);
49 #endif
50 	if (!base)
51 		pr_err("%s: Couldn't map 0x%llx\n", __func__,
52 		       (unsigned long long)paddr);
53 
54 	return base;
55 }
56 
57 static int __init parse_options(struct earlycon_device *device,
58 				char *options)
59 {
60 	struct uart_port *port = &device->port;
61 	int mmio, mmio32, length;
62 	unsigned long addr;
63 
64 	if (!options)
65 		return -ENODEV;
66 
67 	mmio = !strncmp(options, "mmio,", 5);
68 	mmio32 = !strncmp(options, "mmio32,", 7);
69 	if (mmio || mmio32) {
70 		port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32);
71 		options += mmio ? 5 : 7;
72 		addr = simple_strtoul(options, NULL, 0);
73 		port->mapbase = addr;
74 		if (mmio32)
75 			port->regshift = 2;
76 	} else if (!strncmp(options, "io,", 3)) {
77 		port->iotype = UPIO_PORT;
78 		options += 3;
79 		addr = simple_strtoul(options, NULL, 0);
80 		port->iobase = addr;
81 		mmio = 0;
82 	} else if (!strncmp(options, "0x", 2)) {
83 		port->iotype = UPIO_MEM;
84 		addr = simple_strtoul(options, NULL, 0);
85 		port->mapbase = addr;
86 	} else {
87 		return -EINVAL;
88 	}
89 
90 	port->uartclk = BASE_BAUD * 16;
91 
92 	options = strchr(options, ',');
93 	if (options) {
94 		options++;
95 		device->baud = simple_strtoul(options, NULL, 0);
96 		length = min(strcspn(options, " ") + 1,
97 			     (size_t)(sizeof(device->options)));
98 		strlcpy(device->options, options, length);
99 	}
100 
101 	if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM32)
102 		pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
103 			mmio32 ? "32" : "",
104 			(unsigned long long)port->mapbase,
105 			device->options);
106 	else
107 		pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
108 			port->iobase,
109 			device->options);
110 
111 	return 0;
112 }
113 
114 int __init setup_earlycon(char *buf, const char *match,
115 			  int (*setup)(struct earlycon_device *, const char *))
116 {
117 	int err;
118 	size_t len;
119 	struct uart_port *port = &early_console_dev.port;
120 
121 	if (!buf || !match || !setup)
122 		return 0;
123 
124 	len = strlen(match);
125 	if (strncmp(buf, match, len))
126 		return 0;
127 	if (buf[len] && (buf[len] != ','))
128 		return 0;
129 
130 	buf += len + 1;
131 
132 	err = parse_options(&early_console_dev, buf);
133 	/* On parsing error, pass the options buf to the setup function */
134 	if (!err)
135 		buf = NULL;
136 
137 	if (port->mapbase)
138 		port->membase = earlycon_map(port->mapbase, 64);
139 
140 	early_console_dev.con->data = &early_console_dev;
141 	err = setup(&early_console_dev, buf);
142 	if (err < 0)
143 		return err;
144 	if (!early_console_dev.con->write)
145 		return -ENODEV;
146 
147 	register_console(early_console_dev.con);
148 	return 0;
149 }
150 
151 int __init of_setup_earlycon(unsigned long addr,
152 			     int (*setup)(struct earlycon_device *, const char *))
153 {
154 	int err;
155 	struct uart_port *port = &early_console_dev.port;
156 
157 	port->iotype = UPIO_MEM;
158 	port->mapbase = addr;
159 	port->uartclk = BASE_BAUD * 16;
160 	port->membase = earlycon_map(addr, SZ_4K);
161 
162 	early_console_dev.con->data = &early_console_dev;
163 	err = setup(&early_console_dev, NULL);
164 	if (err < 0)
165 		return err;
166 	if (!early_console_dev.con->write)
167 		return -ENODEV;
168 
169 
170 	register_console(early_console_dev.con);
171 	return 0;
172 }
173