---

yaml
---
r: 351193
b: refs/heads/master
c: 2475ff9
h: refs/heads/master
i:
  351191: 9062223
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d6bafb9b821a3a5ddeb600a9fd015085760d818e
+refs/heads/master: 2475ff9d2c6ea3bbfed55c4635426c371f9ad327

trunk/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]

trunk/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

trunk/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>
 

trunk/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)
 

trunk/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

trunk/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)

trunk/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);

trunk/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

trunk/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;