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
21 static 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
early_console_write(struct console * con,const char * s,unsigned n)37 static 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
early_console_putc(char c)65 static 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
early_console_write(struct console * con,const char * s,unsigned n)73 static 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 \
85 selected
86 #endif
87
88 static struct console early_console_prom = {
89 .name = "early",
90 .write = early_console_write,
91 .flags = CON_PRINTBUFFER | CON_BOOT,
92 .index = -1
93 };
94
setup_early_printk(void)95 void __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