1/*
2 * Early printk for Nios2.
3 *
4 * Copyright (C) 2015, Altera Corporation
5 * Copyright (C) 2010, Tobias Klauser <tklauser@distanz.ch>
6 * Copyright (C) 2009, Wind River Systems Inc
7 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
8 *
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License. See the file "COPYING" in the main directory of this archive
11 * for more details.
12 */
13
14#include <linux/console.h>
15#include <linux/init.h>
16#include <linux/kernel.h>
17#include <linux/io.h>
18
19#include <asm/prom.h>
20
21static unsigned long base_addr;
22
23#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
24
25#define ALTERA_JTAGUART_DATA_REG		0
26#define ALTERA_JTAGUART_CONTROL_REG		4
27#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK	0xFFFF0000
28#define ALTERA_JTAGUART_CONTROL_AC_MSK		0x00000400
29
30#define JUART_GET_CR() \
31	__builtin_ldwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG))
32#define JUART_SET_CR(v) \
33	__builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG), v)
34#define JUART_SET_TX(v) \
35	__builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_DATA_REG), v)
36
37static void early_console_write(struct console *con, const char *s, unsigned n)
38{
39	unsigned long status;
40
41	while (n-- && *s) {
42		while (((status = JUART_GET_CR())
43				& ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
44#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
45			if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0)
46				return;	/* no connection activity */
47#endif
48		}
49		JUART_SET_TX(*s);
50		s++;
51	}
52}
53
54#elif defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
55
56#define ALTERA_UART_TXDATA_REG		4
57#define ALTERA_UART_STATUS_REG		8
58#define ALTERA_UART_STATUS_TRDY		0x0040
59
60#define UART_GET_SR() \
61	__builtin_ldwio((void *)(base_addr + ALTERA_UART_STATUS_REG))
62#define UART_SET_TX(v) \
63	__builtin_stwio((void *)(base_addr + ALTERA_UART_TXDATA_REG), v)
64
65static void early_console_putc(char c)
66{
67	while (!(UART_GET_SR() & ALTERA_UART_STATUS_TRDY))
68		;
69
70	UART_SET_TX(c);
71}
72
73static void early_console_write(struct console *con, const char *s, unsigned n)
74{
75	while (n-- && *s) {
76		early_console_putc(*s);
77		if (*s == '\n')
78			early_console_putc('\r');
79		s++;
80	}
81}
82
83#else
84# error Neither SERIAL_ALTERA_JTAGUART_CONSOLE nor SERIAL_ALTERA_UART_CONSOLE \
85selected
86#endif
87
88static struct console early_console_prom = {
89	.name	= "early",
90	.write	= early_console_write,
91	.flags	= CON_PRINTBUFFER | CON_BOOT,
92	.index	= -1
93};
94
95void __init setup_early_printk(void)
96{
97#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) ||	\
98	defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
99	base_addr = of_early_console();
100#else
101	base_addr = 0;
102#endif
103
104	if (!base_addr)
105		return;
106
107#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
108	/* Clear activity bit so BYPASS doesn't stall if we've used JTAG for
109	 * downloading the kernel. This might cause early data to be lost even
110	 * if the JTAG terminal is running.
111	 */
112	JUART_SET_CR(JUART_GET_CR() | ALTERA_JTAGUART_CONTROL_AC_MSK);
113#endif
114
115	early_console = &early_console_prom;
116	register_console(early_console);
117	pr_info("early_console initialized at 0x%08lx\n", base_addr);
118}
119