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
19 #ifdef CONFIG_FIX_EARLYCON_MEM
20 #include <asm/fixmap.h>
21 #endif
22
23 #include <asm/serial.h>
24
25 static struct console early_con = {
26 .name = "earlycon",
27 .flags = CON_PRINTBUFFER | CON_BOOT,
28 .index = -1,
29 };
30
31 static struct earlycon_device early_console_dev = {
32 .con = &early_con,
33 };
34
earlycon_map(unsigned long paddr,size_t size)35 static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
36 {
37 void __iomem *base;
38 #ifdef CONFIG_FIX_EARLYCON_MEM
39 set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
40 base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
41 base += paddr & ~PAGE_MASK;
42 #else
43 base = ioremap(paddr, size);
44 #endif
45 if (!base)
46 pr_err("%s: Couldn't map 0x%llx\n", __func__,
47 (unsigned long long)paddr);
48
49 return base;
50 }
51
parse_options(struct earlycon_device * device,char * options)52 static int __init parse_options(struct earlycon_device *device,
53 char *options)
54 {
55 struct uart_port *port = &device->port;
56 int mmio, mmio32, length, ret;
57 unsigned long addr;
58
59 if (!options)
60 return -ENODEV;
61
62 mmio = !strncmp(options, "mmio,", 5);
63 mmio32 = !strncmp(options, "mmio32,", 7);
64 if (mmio || mmio32) {
65 port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32);
66 options += mmio ? 5 : 7;
67 ret = kstrtoul(options, 0, &addr);
68 if (ret)
69 return ret;
70 port->mapbase = addr;
71 if (mmio32)
72 port->regshift = 2;
73 } else if (!strncmp(options, "io,", 3)) {
74 port->iotype = UPIO_PORT;
75 options += 3;
76 ret = kstrtoul(options, 0, &addr);
77 if (ret)
78 return ret;
79 port->iobase = addr;
80 mmio = 0;
81 } else if (!strncmp(options, "0x", 2)) {
82 port->iotype = UPIO_MEM;
83 ret = kstrtoul(options, 0, &addr);
84 if (ret)
85 return ret;
86 port->mapbase = addr;
87 } else {
88 return -EINVAL;
89 }
90
91 port->uartclk = BASE_BAUD * 16;
92
93 options = strchr(options, ',');
94 if (options) {
95 options++;
96 ret = kstrtouint(options, 0, &device->baud);
97 if (ret)
98 return ret;
99 length = min(strcspn(options, " ") + 1,
100 (size_t)(sizeof(device->options)));
101 strlcpy(device->options, options, length);
102 }
103
104 if (mmio || mmio32)
105 pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
106 mmio32 ? "32" : "",
107 (unsigned long long)port->mapbase,
108 device->options);
109 else
110 pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
111 port->iobase,
112 device->options);
113
114 return 0;
115 }
116
setup_earlycon(char * buf,const char * match,int (* setup)(struct earlycon_device *,const char *))117 int __init setup_earlycon(char *buf, const char *match,
118 int (*setup)(struct earlycon_device *, const char *))
119 {
120 int err;
121 size_t len;
122 struct uart_port *port = &early_console_dev.port;
123
124 if (!buf || !match || !setup)
125 return 0;
126
127 len = strlen(match);
128 if (strncmp(buf, match, len))
129 return 0;
130 if (buf[len] && (buf[len] != ','))
131 return 0;
132
133 buf += len + 1;
134
135 err = parse_options(&early_console_dev, buf);
136 /* On parsing error, pass the options buf to the setup function */
137 if (!err)
138 buf = NULL;
139
140 if (port->mapbase)
141 port->membase = earlycon_map(port->mapbase, 64);
142
143 early_console_dev.con->data = &early_console_dev;
144 err = setup(&early_console_dev, buf);
145 if (err < 0)
146 return err;
147 if (!early_console_dev.con->write)
148 return -ENODEV;
149
150 register_console(early_console_dev.con);
151 return 0;
152 }
153