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
14#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
15
16#include <linux/console.h>
17#include <linux/kernel.h>
18#include <linux/init.h>
19#include <linux/io.h>
20#include <linux/serial_core.h>
21#include <linux/sizes.h>
22#include <linux/mod_devicetable.h>
23
24#ifdef CONFIG_FIX_EARLYCON_MEM
25#include <asm/fixmap.h>
26#endif
27
28#include <asm/serial.h>
29
30static struct console early_con = {
31	.name =		"uart", /* 8250 console switch requires this name */
32	.flags =	CON_PRINTBUFFER | CON_BOOT,
33	.index =	-1,
34};
35
36static struct earlycon_device early_console_dev = {
37	.con = &early_con,
38};
39
40extern struct earlycon_id __earlycon_table[];
41static const struct earlycon_id __earlycon_table_sentinel
42	__used __section(__earlycon_table_end);
43
44static const struct of_device_id __earlycon_of_table_sentinel
45	__used __section(__earlycon_of_table_end);
46
47static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
48{
49	void __iomem *base;
50#ifdef CONFIG_FIX_EARLYCON_MEM
51	set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
52	base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
53	base += paddr & ~PAGE_MASK;
54#else
55	base = ioremap(paddr, size);
56#endif
57	if (!base)
58		pr_err("%s: Couldn't map 0x%llx\n", __func__,
59		       (unsigned long long)paddr);
60
61	return base;
62}
63
64static int __init parse_options(struct earlycon_device *device, char *options)
65{
66	struct uart_port *port = &device->port;
67	int length;
68	unsigned long addr;
69
70	if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
71		return -EINVAL;
72
73	switch (port->iotype) {
74	case UPIO_MEM32:
75		port->regshift = 2;	/* fall-through */
76	case UPIO_MEM:
77		port->mapbase = addr;
78		break;
79	case UPIO_PORT:
80		port->iobase = addr;
81		break;
82	default:
83		return -EINVAL;
84	}
85
86	if (options) {
87		device->baud = simple_strtoul(options, NULL, 0);
88		length = min(strcspn(options, " ") + 1,
89			     (size_t)(sizeof(device->options)));
90		strlcpy(device->options, options, length);
91	}
92
93	if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM32)
94		pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
95			(port->iotype == UPIO_MEM32) ? "32" : "",
96			(unsigned long long)port->mapbase,
97			device->options);
98	else
99		pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
100			port->iobase,
101			device->options);
102
103	return 0;
104}
105
106static int __init register_earlycon(char *buf, const struct earlycon_id *match)
107{
108	int err;
109	struct uart_port *port = &early_console_dev.port;
110
111	/* On parsing error, pass the options buf to the setup function */
112	if (buf && !parse_options(&early_console_dev, buf))
113		buf = NULL;
114
115	port->uartclk = BASE_BAUD * 16;
116	if (port->mapbase)
117		port->membase = earlycon_map(port->mapbase, 64);
118
119	early_console_dev.con->data = &early_console_dev;
120	err = match->setup(&early_console_dev, buf);
121	if (err < 0)
122		return err;
123	if (!early_console_dev.con->write)
124		return -ENODEV;
125
126	register_console(early_console_dev.con);
127	return 0;
128}
129
130/**
131 *	setup_earlycon - match and register earlycon console
132 *	@buf:	earlycon param string
133 *
134 *	Registers the earlycon console matching the earlycon specified
135 *	in the param string @buf. Acceptable param strings are of the form
136 *	   <name>,io|mmio|mmio32,<addr>,<options>
137 *	   <name>,0x<addr>,<options>
138 *	   <name>,<options>
139 *	   <name>
140 *
141 *	Only for the third form does the earlycon setup() method receive the
142 *	<options> string in the 'options' parameter; all other forms set
143 *	the parameter to NULL.
144 *
145 *	Returns 0 if an attempt to register the earlycon was made,
146 *	otherwise negative error code
147 */
148int __init setup_earlycon(char *buf)
149{
150	const struct earlycon_id *match;
151
152	if (!buf || !buf[0])
153		return -EINVAL;
154
155	if (early_con.flags & CON_ENABLED)
156		return -EALREADY;
157
158	for (match = __earlycon_table; match->name[0]; match++) {
159		size_t len = strlen(match->name);
160
161		if (strncmp(buf, match->name, len))
162			continue;
163
164		if (buf[len]) {
165			if (buf[len] != ',')
166				continue;
167			buf += len + 1;
168		} else
169			buf = NULL;
170
171		return register_earlycon(buf, match);
172	}
173
174	return -ENOENT;
175}
176
177/* early_param wrapper for setup_earlycon() */
178static int __init param_setup_earlycon(char *buf)
179{
180	int err;
181
182	/*
183	 * Just 'earlycon' is a valid param for devicetree earlycons;
184	 * don't generate a warning from parse_early_params() in that case
185	 */
186	if (!buf || !buf[0])
187		return 0;
188
189	err = setup_earlycon(buf);
190	if (err == -ENOENT || err == -EALREADY)
191		return 0;
192	return err;
193}
194early_param("earlycon", param_setup_earlycon);
195
196int __init of_setup_earlycon(unsigned long addr,
197			     int (*setup)(struct earlycon_device *, const char *))
198{
199	int err;
200	struct uart_port *port = &early_console_dev.port;
201
202	port->iotype = UPIO_MEM;
203	port->mapbase = addr;
204	port->uartclk = BASE_BAUD * 16;
205	port->membase = earlycon_map(addr, SZ_4K);
206
207	early_console_dev.con->data = &early_console_dev;
208	err = setup(&early_console_dev, NULL);
209	if (err < 0)
210		return err;
211	if (!early_console_dev.con->write)
212		return -ENODEV;
213
214
215	register_console(early_console_dev.con);
216	return 0;
217}
218