/* * 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; #ifdef CONFIG_MMU early_console_reg_tlb_alloc(base_addr); #endif 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; }