diff options
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/early_printk.c | 118 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 12 |
3 files changed, 129 insertions, 2 deletions
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 74239c31e25a..a1cace45e970 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -17,6 +17,7 @@ arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o arm64-obj-$(CONFIG_SMP) += smp.o arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o +arm64-obj-$(CONFIG_EARLY_PRINTK) += early_printk.o obj-y += $(arm64-obj-y) vdso/ obj-m += $(arm64-obj-m) diff --git a/arch/arm64/kernel/early_printk.c b/arch/arm64/kernel/early_printk.c new file mode 100644 index 000000000000..7e320a2edb9b --- /dev/null +++ b/arch/arm64/kernel/early_printk.c @@ -0,0 +1,118 @@ +/* + * Earlyprintk support. + * + * Copyright (C) 2012 ARM Ltd. + * Author: Catalin Marinas <catalin.marinas@arm.com> + * + * 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/string.h> +#include <linux/mm.h> +#include <linux/io.h> + +#include <linux/amba/serial.h> + +static void __iomem *early_base; +static void (*printch)(char ch); + +/* + * PL011 single character TX. + */ +static void pl011_printch(char ch) +{ + while (readl_relaxed(early_base + UART01x_FR) & UART01x_FR_TXFF) + ; + writeb_relaxed(ch, early_base + UART01x_DR); + while (readl_relaxed(early_base + UART01x_FR) & UART01x_FR_BUSY) + ; +} + +struct earlycon_match { + const char *name; + void (*printch)(char ch); +}; + +static const struct earlycon_match earlycon_match[] __initconst = { + { .name = "pl011", .printch = pl011_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 = { + .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; + } + /* no options parsing yet */ + + if (paddr) + early_base = early_io_map(paddr, EARLYCON_IOBASE); + + printch = match->printch; + register_console(&early_console); + + return 0; +} + +early_param("earlyprintk", setup_early_printk); diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 368ad1f7c36c..0a0a49756826 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -82,10 +82,8 @@ #ifdef CONFIG_ARM64_64K_PAGES #define MM_MMUFLAGS PTE_ATTRINDX(MT_NORMAL) | PTE_FLAGS -#define IO_MMUFLAGS PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_XN | PTE_FLAGS #else #define MM_MMUFLAGS PMD_ATTRINDX(MT_NORMAL) | PMD_FLAGS -#define IO_MMUFLAGS PMD_ATTRINDX(MT_DEVICE_nGnRE) | PMD_SECT_XN | PMD_FLAGS #endif /* @@ -368,6 +366,7 @@ ENDPROC(__calc_phys_offset) * - identity mapping to enable the MMU (low address, TTBR0) * - first few MB of the kernel linear mapping to jump to once the MMU has * been enabled, including the FDT blob (TTBR1) + * - UART mapping if CONFIG_EARLY_PRINTK is enabled (TTBR1) */ __create_page_tables: pgtbl x25, x26, x24 // idmap_pg_dir and swapper_pg_dir addresses @@ -420,6 +419,15 @@ __create_page_tables: sub x6, x6, #1 // inclusive range create_block_map x0, x7, x3, x5, x6 1: +#ifdef CONFIG_EARLY_PRINTK + /* + * Create the pgd entry for the UART mapping. The full mapping is done + * later based earlyprintk kernel parameter. + */ + ldr x5, =EARLYCON_IOBASE // UART virtual address + add x0, x26, #2 * PAGE_SIZE // section table address + create_pgd_entry x26, x0, x5, x6, x7 +#endif ret ENDPROC(__create_page_tables) .ltorg |