From: Greentime Hu <greentime@xxxxxxxxxxxxx> Signed-off-by: Rick Chen <rick@xxxxxxxxxxxxx> Signed-off-by: Greentime Hu <greentime@xxxxxxxxxxxxx> --- arch/nds32/kernel/early_printk.c | 124 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 arch/nds32/kernel/early_printk.c diff --git a/arch/nds32/kernel/early_printk.c b/arch/nds32/kernel/early_printk.c new file mode 100644 index 0000000..269c3cd --- /dev/null +++ b/arch/nds32/kernel/early_printk.c @@ -0,0 +1,124 @@ +/* + * Copyright (C) 2005-2017 Andes Technology Corporation + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/kernel.h> +#include <linux/console.h> +#include <linux/init.h> +#include <linux/io.h> + +#include <linux/serial_reg.h> + +extern void __iomem *early_io_map(phys_addr_t phys); +static void __iomem *early_base; +static void (*printch) (char ch); + +/* + * 8250/16550 (8-bit aligned registers) single character TX. + */ +static void uart8250_8bit_printch(char ch) +{ + while (!(readb(early_base + UART_LSR) & UART_LSR_THRE)) ; + writeb(ch, early_base + UART_TX); +} + +/* + * 8250/16550 (32-bit aligned registers) single character TX. + */ +static void uart8250_32bit_printch(char ch) +{ + while (!(readl(early_base + (UART_LSR << 2)) & UART_LSR_THRE)) ; + writel(ch, early_base + (UART_TX << 2)); +} + +struct earlycon_match { + const char *name; + void (*printch) (char ch); +}; + +static const struct earlycon_match earlycon_match[] __initconst = { + {.name = "uart8250-8bit",.printch = uart8250_8bit_printch,}, + {.name = "uart8250-32bit",.printch = uart8250_32bit_printch,}, + {} +}; + +static void early_write(struct console *con, const char *s, unsigned n) +{ + while (n-- > 0) { + if (*s == '\n') + printch('\r'); + printch(*s); + s++; + } +} + +static struct console early_console_dev = { + .name = "earlycon", + .write = early_write, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; + +/* + * Parse earlyprintk=... parameter in the format: + * + * <name>[,<addr>][,<options>] + * + * and register the early console. It is assumed that the UART has been + * initialised by the bootloader already. + */ +static int __init setup_early_printk(char *buf) +{ + const struct earlycon_match *match = earlycon_match; + phys_addr_t paddr = 0; + + if (!buf) { + pr_warning("No earlyprintk arguments passed.\n"); + return 0; + } + + while (match->name) { + size_t len = strlen(match->name); + if (!strncmp(buf, match->name, len)) { + buf += len; + break; + } + match++; + } + if (!match->name) { + pr_warning("Unknown earlyprintk arguments: %s\n", buf); + return 0; + } + + /* I/O address */ + if (!strncmp(buf, ",0x", 3)) { + char *e; + paddr = simple_strtoul(buf + 1, &e, 16); + buf = e; + } + + if (paddr) + early_base = early_io_map(paddr); + + if (!strcmp(CONFIG_NDS32_BUILTIN_DTB, "ae3xx")) + early_base += 32; + + printch = match->printch; + register_console(&early_console_dev); + + return 0; +} + +early_param("earlyprintk", setup_early_printk); -- 1.7.9.5
