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Diffstat (limited to 'arch/microblaze/kernel/early_printk.c')
| -rw-r--r-- | arch/microblaze/kernel/early_printk.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/early_printk.c b/arch/microblaze/kernel/early_printk.c new file mode 100644 index 000000000..365f2d53f --- /dev/null +++ b/arch/microblaze/kernel/early_printk.c @@ -0,0 +1,184 @@ +/* + * 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 base_addr; + +#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE +static void early_printk_uartlite_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 = 1000000; + /* 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_uartlite_write(struct console *unused, + const char *s, unsigned n) +{ + while (*s && n-- > 0) { + if (*s == '\n') + early_printk_uartlite_putc('\r'); + early_printk_uartlite_putc(*s); + s++; + } +} + +static struct console early_serial_uartlite_console = { + .name = "earlyser", + .write = early_printk_uartlite_write, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; +#endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */ + +#ifdef CONFIG_SERIAL_8250_CONSOLE +static void early_printk_uart16550_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. + */ + + #define UART_LSR_TEMT 0x40 /* Transmitter empty */ + #define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */ + #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) + + unsigned retries = 10000; + + while (--retries && + !((in_be32(base_addr + 0x14) & BOTH_EMPTY) == BOTH_EMPTY)) + ; + + if (retries) + out_be32(base_addr, c & 0xff); +} + +static void early_printk_uart16550_write(struct console *unused, + const char *s, unsigned n) +{ + while (*s && n-- > 0) { + if (*s == '\n') + early_printk_uart16550_putc('\r'); + early_printk_uart16550_putc(*s); + s++; + } +} + +static struct console early_serial_uart16550_console = { + .name = "earlyser", + .write = early_printk_uart16550_write, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; +#endif /* CONFIG_SERIAL_8250_CONSOLE */ + +int __init setup_early_printk(char *opt) +{ + int version = 0; + + if (early_console) + return 1; + + base_addr = of_early_console(&version); + if (base_addr) { +#ifdef CONFIG_MMU + early_console_reg_tlb_alloc(base_addr); +#endif + switch (version) { +#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE + case UARTLITE: + pr_info("Early console on uartlite at 0x%08x\n", + base_addr); + early_console = &early_serial_uartlite_console; + break; +#endif +#ifdef CONFIG_SERIAL_8250_CONSOLE + case UART16550: + pr_info("Early console on uart16650 at 0x%08x\n", + base_addr); + early_console = &early_serial_uart16550_console; + break; +#endif + default: + pr_info("Unsupported early console %d\n", + version); + return 1; + } + + register_console(early_console); + return 0; + } + return 1; +} + +/* Remap early console to virtual address and do not allocate one TLB + * only for early console because of performance degression */ +void __init remap_early_printk(void) +{ + if (!early_console) + return; + pr_info("early_printk_console remapping from 0x%x to ", base_addr); + base_addr = (u32) ioremap(base_addr, PAGE_SIZE); + pr_cont("0x%x\n", base_addr); + +#ifdef CONFIG_MMU + /* + * Early console is on the top of skipped TLB entries + * decrease tlb_skip size ensure that hardcoded TLB entry will be + * used by generic algorithm + * FIXME check if early console mapping is on the top by rereading + * TLB entry and compare baseaddr + * mts rtlbx, (tlb_skip - 1) + * nop + * mfs rX, rtlblo + * nop + * cmp rX, orig_base_addr + */ + tlb_skip -= 1; +#endif +} + +void __init disable_early_printk(void) +{ + if (!early_console) + return; + pr_warn("disabling early console\n"); + unregister_console(early_console); + early_console = NULL; +} |