From 89272a51b322aa14332d58896b9d377ea9b4e551 Mon Sep 17 00:00:00 2001 From: Michal Simek Date: Fri, 27 Mar 2009 14:25:22 +0100 Subject: microblaze_v8: early_printk support Reviewed-by: Ingo Molnar Acked-by: Stephen Neuendorffer Acked-by: John Linn Acked-by: John Williams Signed-off-by: Michal Simek --- arch/microblaze/kernel/early_printk.c | 107 ++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) create mode 100644 arch/microblaze/kernel/early_printk.c (limited to 'arch/microblaze/kernel/early_printk.c') 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 + * Copyright (C) 2007-2009 PetaLogix + * Copyright (C) 2003-2006 Yasushi SHOJI + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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; +} -- cgit v1.2.3-59-g8ed1b From 6e60c14810d8da792e418fdcb2110b4185d1b9a2 Mon Sep 17 00:00:00 2001 From: Roel Kluin Date: Thu, 16 Apr 2009 22:49:17 +0200 Subject: microblaze: iowrite upon timeout retries reaches -1, so the iowrite occurrs upon timeout. Acked-by: John Williams Signed-off-by: Roel Kluin Signed-off-by: Michal Simek --- arch/microblaze/kernel/early_printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/microblaze/kernel/early_printk.c') diff --git a/arch/microblaze/kernel/early_printk.c b/arch/microblaze/kernel/early_printk.c index 62cc78993f44..4b0f0fdb9ca0 100644 --- a/arch/microblaze/kernel/early_printk.c +++ b/arch/microblaze/kernel/early_printk.c @@ -36,7 +36,7 @@ static void early_printk_putc(char c) unsigned retries = 10000; /* read status bit - 0x8 offset */ - while (retries-- && (in_be32(base_addr + 8) & (1 << 3))) + while (--retries && (in_be32(base_addr + 8) & (1 << 3))) ; /* Only attempt the iowrite if we didn't timeout */ -- cgit v1.2.3-59-g8ed1b