diff options
| -rw-r--r-- | arch/microblaze/kernel/early_printk.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/early_printk.c b/arch/microblaze/kernel/early_printk.c new file mode 100644 index 000000000000..62cc78993f44 --- /dev/null +++ b/arch/microblaze/kernel/early_printk.c @@ -0,0 +1,107 @@ +/* + * Early printk support for Microblaze. + * + * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu> + * Copyright (C) 2007-2009 PetaLogix + * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-techno.com> + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include <linux/console.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/string.h> +#include <linux/tty.h> +#include <linux/io.h> +#include <asm/processor.h> +#include <linux/fcntl.h> +#include <asm/setup.h> +#include <asm/prom.h> + +static u32 early_console_initialized; +static u32 base_addr; + +static void early_printk_putc(char c) +{ + /* + * Limit how many times we'll spin waiting for TX FIFO status. + * This will prevent lockups if the base address is incorrectly + * set, or any other issue on the UARTLITE. + * This limit is pretty arbitrary, unless we are at about 10 baud + * we'll never timeout on a working UART. + */ + + unsigned retries = 10000; + /* read status bit - 0x8 offset */ + while (retries-- && (in_be32(base_addr + 8) & (1 << 3))) + ; + + /* Only attempt the iowrite if we didn't timeout */ + /* write to TX_FIFO - 0x4 offset */ + if (retries) + out_be32(base_addr + 4, c & 0xff); +} + +static void early_printk_write(struct console *unused, + const char *s, unsigned n) +{ + while (*s && n-- > 0) { + early_printk_putc(*s); + if (*s == '\n') + early_printk_putc('\r'); + s++; + } +} + +static struct console early_serial_console = { + .name = "earlyser", + .write = early_printk_write, + .flags = CON_PRINTBUFFER, + .index = -1, +}; + +static struct console *early_console = &early_serial_console; + +void early_printk(const char *fmt, ...) +{ + char buf[512]; + int n; + va_list ap; + + if (early_console_initialized) { + va_start(ap, fmt); + n = vscnprintf(buf, 512, fmt, ap); + early_console->write(early_console, buf, n); + va_end(ap); + } +} + +int __init setup_early_printk(char *opt) +{ + if (early_console_initialized) + return 1; + + base_addr = early_uartlite_console(); + if (base_addr) { + early_console_initialized = 1; + early_printk("early_printk_console is enabled at 0x%08x\n", + base_addr); + + /* register_console(early_console); */ + + return 0; + } else + return 1; +} + +void __init disable_early_printk(void) +{ + if (!early_console_initialized || !early_console) + return; + printk(KERN_WARNING "disabling early console\n"); + unregister_console(early_console); + early_console_initialized = 0; +} |