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}