2 * Early printk support for Microblaze.
4 * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
5 * Copyright (C) 2007-2009 PetaLogix
6 * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-techno.com>
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License. See the file "COPYING" in the main directory of this archive
13 #include <linux/console.h>
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/string.h>
17 #include <linux/tty.h>
19 #include <asm/processor.h>
20 #include <linux/fcntl.h>
21 #include <asm/setup.h>
24 static u32 early_console_initialized
;
27 static void early_printk_uartlite_putc(char c
)
30 * Limit how many times we'll spin waiting for TX FIFO status.
31 * This will prevent lockups if the base address is incorrectly
32 * set, or any other issue on the UARTLITE.
33 * This limit is pretty arbitrary, unless we are at about 10 baud
34 * we'll never timeout on a working UART.
37 unsigned retries
= 10000;
38 /* read status bit - 0x8 offset */
39 while (--retries
&& (in_be32(base_addr
+ 8) & (1 << 3)))
42 /* Only attempt the iowrite if we didn't timeout */
43 /* write to TX_FIFO - 0x4 offset */
45 out_be32(base_addr
+ 4, c
& 0xff);
48 static void early_printk_uartlite_write(struct console
*unused
,
49 const char *s
, unsigned n
)
51 while (*s
&& n
-- > 0) {
52 early_printk_uartlite_putc(*s
);
54 early_printk_uartlite_putc('\r');
59 static struct console early_serial_uartlite_console
= {
61 .write
= early_printk_uartlite_write
,
62 .flags
= CON_PRINTBUFFER
,
66 static struct console
*early_console
;
68 void early_printk(const char *fmt
, ...)
74 if (early_console_initialized
) {
76 n
= vscnprintf(buf
, 512, fmt
, ap
);
77 early_console
->write(early_console
, buf
, n
);
82 int __init
setup_early_printk(char *opt
)
84 if (early_console_initialized
)
87 base_addr
= early_uartlite_console();
89 early_console_initialized
= 1;
91 early_console_reg_tlb_alloc(base_addr
);
93 early_console
= &early_serial_uartlite_console
;
94 early_printk("early_printk_console is enabled at 0x%08x\n",
97 /* register_console(early_console); */
104 void __init
disable_early_printk(void)
106 if (!early_console_initialized
|| !early_console
)
108 printk(KERN_WARNING
"disabling early console\n");
109 unregister_console(early_console
);
110 early_console_initialized
= 0;