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-rw-r--r--Documentation/arm64/memory.txt2
-rw-r--r--arch/arm64/Kconfig.debug9
-rw-r--r--arch/arm64/include/asm/io.h3
-rw-r--r--arch/arm64/include/asm/memory.h1
-rw-r--r--arch/arm64/include/asm/mmu.h1
-rw-r--r--arch/arm64/kernel/Makefile1
-rw-r--r--arch/arm64/kernel/early_printk.c118
-rw-r--r--arch/arm64/kernel/head.S12
-rw-r--r--arch/arm64/mm/mmu.c42
9 files changed, 187 insertions, 2 deletions
diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt
index d758702fc03c..5f583af0a6e1 100644
--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt
@@ -35,6 +35,8 @@ ffffffbc00000000 ffffffbdffffffff 8GB vmemmap
ffffffbe00000000 ffffffbffbbfffff ~8GB [guard, future vmmemap]
+ffffffbffbc00000 ffffffbffbdfffff 2MB earlyprintk device
+
ffffffbffbe00000 ffffffbffbe0ffff 64KB PCI I/O space
ffffffbbffff0000 ffffffbcffffffff ~2MB [guard]
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index d7553f2bda66..79871cd78da8 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -24,4 +24,13 @@ config DEBUG_STACK_USAGE
Enables the display of the minimum amount of free stack which each
task has ever had available in the sysrq-T output.
+config EARLY_PRINTK
+ bool "Early printk support"
+ default y
+ help
+ Say Y here if you want to have an early console using the
+ earlyprintk=<name>[,<addr>][,<options>] kernel parameter. It
+ is assumed that the early console device has been initialised
+ by the boot loader prior to starting the Linux kernel.
+
endmenu
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index d2f05a608274..57f12c991de2 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -230,6 +230,9 @@ extern void __iounmap(volatile void __iomem *addr);
#define ioremap_wc(addr, size) __ioremap((addr), (size), __pgprot(PROT_NORMAL_NC))
#define iounmap __iounmap
+#define PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF)
+#define PROT_SECT_DEVICE_nGnRE (PROT_SECT_DEFAULT | PTE_PXN | PTE_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE))
+
#define ARCH_HAS_IOREMAP_WC
#include <asm-generic/iomap.h>
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 1cac16a001cb..381f556b664e 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -43,6 +43,7 @@
#define PAGE_OFFSET UL(0xffffffc000000000)
#define MODULES_END (PAGE_OFFSET)
#define MODULES_VADDR (MODULES_END - SZ_64M)
+#define EARLYCON_IOBASE (MODULES_VADDR - SZ_4M)
#define VA_BITS (39)
#define TASK_SIZE_64 (UL(1) << VA_BITS)
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index d4f7fd5b9e33..2494fc01896a 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -26,5 +26,6 @@ typedef struct {
extern void paging_init(void);
extern void setup_mm_for_reboot(void);
+extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
#endif
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
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a6885d896ab6..f4dd585898c5 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -25,6 +25,7 @@
#include <linux/nodemask.h>
#include <linux/memblock.h>
#include <linux/fs.h>
+#include <linux/io.h>
#include <asm/cputype.h>
#include <asm/sections.h>
@@ -251,6 +252,47 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt,
} while (pgd++, addr = next, addr != end);
}
+#ifdef CONFIG_EARLY_PRINTK
+/*
+ * Create an early I/O mapping using the pgd/pmd entries already populated
+ * in head.S as this function is called too early to allocated any memory. The
+ * mapping size is 2MB with 4KB pages or 64KB or 64KB pages.
+ */
+void __iomem * __init early_io_map(phys_addr_t phys, unsigned long virt)
+{
+ unsigned long size, mask;
+ bool page64k = IS_ENABLED(ARM64_64K_PAGES);
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ /*
+ * No early pte entries with !ARM64_64K_PAGES configuration, so using
+ * sections (pmd).
+ */
+ size = page64k ? PAGE_SIZE : SECTION_SIZE;
+ mask = ~(size - 1);
+
+ pgd = pgd_offset_k(virt);
+ pud = pud_offset(pgd, virt);
+ if (pud_none(*pud))
+ return NULL;
+ pmd = pmd_offset(pud, virt);
+
+ if (page64k) {
+ if (pmd_none(*pmd))
+ return NULL;
+ pte = pte_offset_kernel(pmd, virt);
+ set_pte(pte, __pte((phys & mask) | PROT_DEVICE_nGnRE));
+ } else {
+ set_pmd(pmd, __pmd((phys & mask) | PROT_SECT_DEVICE_nGnRE));
+ }
+
+ return (void __iomem *)((virt & mask) + (phys & ~mask));
+}
+#endif
+
static void __init map_mem(void)
{
struct memblock_region *reg;