ARM: Generalize armv7 as arm.

There are ARM systems which are essentially heterogeneous multicores where
some cores implement a different ARM architecture version than other cores. A
specific example is the tegra124 which boots on an ARMv4 coprocessor while
most code, including most of the firmware, runs on the main ARMv7 core. To
support SOCs like this, the plan is to generalize the ARM architecture so that
all versions are available, and an SOC/CPU can then select what architecture
variant should be used for each component of the firmware; bootblock,
romstage, and ramstage.

Old-Change-Id: I22e048c3bc72bd56371e14200942e436c1e312c2
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/171338
Reviewed-by: Gabe Black <gabeblack@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 8423a41529da0ff67fb9873be1e2beb30b09ae2d)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>

ARM: Split out ARMv7 code and make it possible to have other arch versions.

We don't always want to use ARMv7 code when building for ARM, so we should
separate out the ARMv7 code so it can be excluded, and also make it possible
to include code for some other version of the architecture instead, all per
build component for cases where we need more than one architecture version
at a time.

The tegra124 bootblock will ultimately need to be ARMv4, but until we have
some ARMv4 code to switch over to we can leave it set to ARMv7.

Old-Change-Id: Ia982c91057fac9c252397b7c866224f103761cc7
Reviewed-on: https://chromium-review.googlesource.com/171400
Reviewed-by: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 799514e6060aa97acdcf081b5c48f965be134483)

Squashed two related patches for splitting ARM support into general
ARM support and ARMv7 specific pieces.

Change-Id: Ic6511507953a2223c87c55f90252c4a4e1dd6010
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6782
Tested-by: build bot (Jenkins)

9 files changed, 1153 insertions, 0 deletions

diff --git a/src/arch/arm/armv7/Kconfig b/src/arch/arm/armv7/Kconfig
new file mode 100644
index 0000000000..f8e0205c40
--- /dev/null
+++ b/src/arch/arm/armv7/Kconfig
@@ -0,0 +1,11 @@
+config ARCH_BOOTBLOCK_ARMV7
+	def_bool n
+	select ARCH_BOOTBLOCK_ARM
+
+config ARCH_ROMSTAGE_ARMV7
+	def_bool n
+	select ARCH_ROMSTAGE_ARM
+
+config ARCH_RAMSTAGE_ARMV7
+	def_bool n
+	select ARCH_RAMSTAGE_ARM
diff --git a/src/arch/arm/armv7/Makefile.inc b/src/arch/arm/armv7/Makefile.inc
new file mode 100644
index 0000000000..bcd7d9e46d
--- /dev/null
+++ b/src/arch/arm/armv7/Makefile.inc
@@ -0,0 +1,71 @@
+################################################################################
+##
+## This file is part of the coreboot project.
+##
+## Copyright (C) 2013 The ChromiumOS Authors
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; version 2 of the License.
+##
+## 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, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+##
+###############################################################################
+
+armv7_flags = -march=armv7-a -mthumb -mthumb-interwork \
+	-I$(src)/arch/arm/include/armv7/
+
+###############################################################################
+# bootblock
+###############################################################################
+
+ifeq ($(CONFIG_ARCH_BOOTBLOCK_ARMV7),y)
+
+ifneq ($(CONFIG_ARM_BOOTBLOCK_CUSTOM),y)
+bootblock-y += bootblock.S
+bootblock-$(CONFIG_BOOTBLOCK_SIMPLE) += bootblock_simple.c
+endif
+
+bootblock-y += cache.c
+bootblock-y += mmu.c
+
+CFLAGS_bootblock += $(armv7_flags)
+CPPFLAGS_bootblock += $(armv7_flags)
+
+endif # CONFIG_ARCH_BOOTBLOCK_ARMV7
+
+###############################################################################
+# romstage
+###############################################################################
+
+ifeq ($(CONFIG_ARCH_ROMSTAGE_ARMV7),y)
+
+romstage-y += cache.c
+
+CFLAGS_romstage += $(armv7_flags)
+CPPFLAGS_romstage += $(armv7_flags)
+
+endif # CONFIG_ARCH_ROMSTAGE_ARMV7
+
+###############################################################################
+# ramstage
+###############################################################################
+
+ifeq ($(CONFIG_ARCH_RAMSTAGE_ARMV7),y)
+
+ramstage-y += cache.c
+ramstage-y += exception.c
+ramstage-y += exception_asm.S
+ramstage-y += mmu.c
+
+CFLAGS_ramstage += $(armv7_flags)
+CPPFLAGS_ramstage += $(armv7_flags)
+
+endif # CONFIG_ARCH_RAMSTAGE_ARMV7
diff --git a/src/arch/arm/armv7/bootblock.S b/src/arch/arm/armv7/bootblock.S
new file mode 100644
index 0000000000..b28a787839
--- /dev/null
+++ b/src/arch/arm/armv7/bootblock.S
@@ -0,0 +1,113 @@
+/*
+ * Early initialization code for ARMv7 architecture.
+ *
+ * This file is based off of the OMAP3530/ARM Cortex start.S file from Das
+ * U-Boot, which itself got the file from armboot.
+ *
+ * Copyright (c) 2004	Texas Instruments <r-woodruff2@ti.com>
+ * Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
+ * Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
+ * Copyright (c) 2002	Gary Jennejohn <garyj@denx.de>
+ * Copyright (c) 2003	Richard Woodruff <r-woodruff2@ti.com>
+ * Copyright (c) 2003	Kshitij <kshitij@ti.com>
+ * Copyright (c) 2006-2008 Syed Mohammed Khasim <x0khasim@ti.com>
+ * Copyright (c) 2013   The Chromium OS Authors
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+.section ".start", "a", %progbits
+.globl _start
+_start: b	reset
+	.balignl 16,0xdeadbeef
+
+_cbfs_master_header:
+	/* The CBFS master header is inserted by cbfstool at the first
+	 * aligned offset after the above anchor string is found.
+	 * Hence, we leave some space for it.
+	 */
+	.skip 128			@ Assumes 64-byte alignment
+
+reset:
+	/*
+	 * Set the cpu to System mode with IRQ and FIQ disabled. Prefetch/Data
+	 * aborts may happen early and crash before the abort handlers are
+	 * installed, but at least the problem will show up near the code that
+	 * causes it.
+	 */
+	msr	cpsr_cxf, #0xdf
+
+	/*
+	 * From Cortex-A Series Programmer's Guide:
+	 * Only CPU 0 performs initialization. Other CPUs go into WFI
+	 * to do this, first work out which CPU this is
+	 * this code typically is run before any other initialization step
+	 */
+	mrc p15, 0, r1, c0, c0, 5	@ Read Multiprocessor Affinity Register
+	and r1, r1, #0x3 @ Extract CPU ID bits
+	cmp r1, #0
+	bne wait_for_interrupt		@ If this is not core0, wait
+
+	/*
+	 * Initialize the stack to a known value. This is used to check for
+	 * stack overflow later in the boot process.
+	 */
+	ldr	r0, .Stack
+	ldr	r1, .Stack_size
+	sub	r0, r0, r1
+	ldr	r1, .Stack
+	ldr	r2, =0xdeadbeef
+init_stack_loop:
+	str	r2, [r0]
+	add	r0, #4
+	cmp	r0, r1
+	bne	init_stack_loop
+
+/* Set stackpointer in internal RAM to call board_init_f */
+call_bootblock:
+	ldr	sp, .Stack /* Set up stack pointer */
+	ldr	r0,=0x00000000
+	 /*
+	  * The current design of cpu_info places the
+	  * struct at the top of the stack. The number of
+	  * words pushed must be at least as large as that
+	  * struct.
+	  */
+	push	{r0-r2}
+	bic	sp, sp, #7 /* 8-byte alignment for ABI compliance */
+	/*
+	 * Use "bl" instead of "b" even though we do not intend to return.
+	 * "bl" gets compiled to "blx" if we're transitioning from ARM to
+	 * Thumb. However, "b" will not and GCC may attempt to create a
+	 * wrapper which is currently broken.
+	 */
+	bl	main
+
+wait_for_interrupt:
+	wfi
+	mov	pc, lr			@ back to my caller
+
+/* we do it this way because it's a 32-bit constant and
+ * in some cases too far away to be loaded as just an offset
+ * from IP
+ */
+.align 2
+.Stack:
+	.word CONFIG_STACK_TOP
+.align 2
+/* create this size the same way we do in coreboot_ram.ld: top-bottom */
+.Stack_size:
+	.word CONFIG_STACK_TOP - CONFIG_STACK_BOTTOM
diff --git a/src/arch/arm/armv7/bootblock_simple.c b/src/arch/arm/armv7/bootblock_simple.c
new file mode 100644
index 0000000000..f447034029
--- /dev/null
+++ b/src/arch/arm/armv7/bootblock_simple.c
@@ -0,0 +1,63 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2010 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#include <arch/cache.h>
+#include <arch/hlt.h>
+#include <arch/stages.h>
+#include <bootblock_common.h>
+#include <cbfs.h>
+#include <console/console.h>
+#include <smp/node.h>
+
+void main(void)
+{
+	const char *stage_name = "fallback/romstage";
+	void *entry;
+	uint32_t sctlr;
+
+	/* Globally disable MMU, caches, and branch prediction (these should
+	 * be disabled by default on reset) */
+	sctlr = read_sctlr();
+	sctlr &= ~(SCTLR_M | SCTLR_C | SCTLR_Z | SCTLR_I);
+	write_sctlr(sctlr);
+
+	arm_invalidate_caches();
+
+	/*
+	 * Re-enable icache and branch prediction. MMU and dcache will be
+	 * set up later.
+	 */
+	sctlr = read_sctlr();
+	sctlr |= SCTLR_Z | SCTLR_I;
+	write_sctlr(sctlr);
+
+	bootblock_cpu_init();
+	bootblock_mainboard_init();
+
+#if CONFIG_BOOTBLOCK_CONSOLE
+	console_init();
+#endif
+
+	entry = cbfs_load_stage(CBFS_DEFAULT_MEDIA, stage_name);
+
+	if (entry) stage_exit(entry);
+	hlt();
+}
diff --git a/src/arch/arm/armv7/cache.c b/src/arch/arm/armv7/cache.c
new file mode 100644
index 0000000000..acd1f9aefa
--- /dev/null
+++ b/src/arch/arm/armv7/cache.c
@@ -0,0 +1,328 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * cache.c: Cache maintenance routines for ARMv7-A and ARMv7-R
+ *
+ * Reference: ARM Architecture Reference Manual, ARMv7-A and ARMv7-R edition
+ */
+
+#include <stdint.h>
+
+#include <arch/cache.h>
+
+#define bitmask(high, low) ((1UL << (high)) + \
+			((1UL << (high)) - 1) - ((1UL << (low)) - 1))
+
+/* Basic log2() implementation. Note: log2(0) is 0 for our purposes. */
+/* FIXME: src/include/lib.h is difficult to work with due to romcc */
+static unsigned long log2(unsigned long u)
+{
+	int i = 0;
+
+	while (u >>= 1)
+		i++;
+
+	return i;
+}
+
+void tlb_invalidate_all(void)
+{
+	/*
+	 * FIXME: ARMv7 Architecture Ref. Manual claims that the distinction
+	 * instruction vs. data TLBs is deprecated in ARMv7, however this does
+	 * not seem to be the case as of Cortex-A15.
+	 */
+	tlbiall();
+	dtlbiall();
+	itlbiall();
+	isb();
+	dsb();
+}
+
+void icache_invalidate_all(void)
+{
+	/*
+	 * icache can be entirely invalidated with one operation.
+	 * Note: If branch predictors are architecturally-visible, ICIALLU
+	 * also performs a BPIALL operation (B2-1283 in arch manual)
+	 */
+	iciallu();
+	isb();
+}
+
+enum dcache_op {
+	OP_DCCSW,
+	OP_DCCISW,
+	OP_DCISW,
+	OP_DCCIMVAC,
+	OP_DCCMVAC,
+	OP_DCIMVAC,
+};
+
+/*
+ * Do a dcache operation on entire cache by set/way. This is done for
+ * portability because mapping of memory address to cache location is
+ * implementation defined (See note on "Requirements for operations by
+ * set/way" in arch ref. manual).
+ */
+static void dcache_op_set_way(enum dcache_op op)
+{
+	uint32_t ccsidr;
+	unsigned int associativity, num_sets, linesize_bytes;
+	unsigned int set, way;
+	unsigned int level;
+
+	level = (read_csselr() >> 1) & 0x7;
+
+	/*
+	 * dcache must be invalidated by set/way for portability since virtual
+	 * memory mapping is system-defined. The number of sets and
+	 * associativity is given by CCSIDR. We'll use DCISW to invalidate the
+	 * dcache.
+	 */
+	ccsidr = read_ccsidr();
+
+	/* FIXME: rounding up required here? */
+	num_sets = ((ccsidr & bitmask(27, 13)) >> 13) + 1;
+	associativity = ((ccsidr & bitmask(12, 3)) >> 3) + 1;
+	/* FIXME: do we need to use CTR.DminLine here? */
+	linesize_bytes = (1 << ((ccsidr & 0x7) + 2)) * 4;
+
+	dsb();
+
+	/*
+	 * Set/way operations require an interesting bit packing. See section
+	 * B4-35 in the ARMv7 Architecture Reference Manual:
+	 *
+	 * A: Log2(associativity)
+	 * B: L+S
+	 * L: Log2(linesize)
+	 * S: Log2(num_sets)
+	 *
+	 * The bits are packed as follows:
+	 *  31  31-A        B B-1    L L-1   4 3   1 0
+	 * |---|-------------|--------|-------|-----|-|
+	 * |Way|    zeros    |   Set  | zeros |level|0|
+	 * |---|-------------|--------|-------|-----|-|
+	 */
+	for (way = 0; way < associativity; way++) {
+		for (set = 0; set < num_sets; set++) {
+			uint32_t val = 0;
+			val |= way << (32 - log2(associativity));
+			val |= set << log2(linesize_bytes);
+			val |= level << 1;
+			switch(op) {
+			case OP_DCCISW:
+				dccisw(val);
+				break;
+			case OP_DCISW:
+				dcisw(val);
+				break;
+			case OP_DCCSW:
+				dccsw(val);
+				break;
+			default:
+				break;
+			}
+		}
+	}
+	isb();
+}
+
+static void dcache_foreach(enum dcache_op op)
+{
+	uint32_t clidr;
+	int level;
+
+	clidr = read_clidr();
+	for (level = 0; level < 7; level++) {
+		unsigned int ctype = (clidr >> (level * 3)) & 0x7;
+		uint32_t csselr;
+
+		switch(ctype) {
+		case 0x2:
+		case 0x3:
+		case 0x4:
+			csselr = level << 1;
+			write_csselr(csselr);
+			dcache_op_set_way(op);
+			break;
+		default:
+			/* no cache, icache only, or reserved */
+			break;
+		}
+	}
+}
+
+void dcache_clean_all(void)
+{
+	dcache_foreach(OP_DCCSW);
+}
+
+void dcache_clean_invalidate_all(void)
+{
+	dcache_foreach(OP_DCCISW);
+}
+
+void dcache_invalidate_all(void)
+{
+	dcache_foreach(OP_DCISW);
+}
+
+static unsigned int line_bytes(void)
+{
+	uint32_t ccsidr;
+	unsigned int size;
+
+	ccsidr = read_ccsidr();
+	/* [2:0] - Indicates (Log2(number of words in cache line)) - 2 */
+	size = 1 << ((ccsidr & 0x7) + 2);	/* words per line */
+	size *= sizeof(unsigned int);		/* bytes per line */
+
+	return size;
+}
+
+/*
+ * Do a dcache operation by modified virtual address. This is useful for
+ * maintaining coherency in drivers which do DMA transfers and only need to
+ * perform cache maintenance on a particular memory range rather than the
+ * entire cache.
+ */
+static void dcache_op_mva(void const *addr, size_t len, enum dcache_op op)
+{
+	unsigned long line, linesize;
+
+	linesize = line_bytes();
+	line = (uint32_t)addr & ~(linesize - 1);
+
+	dsb();
+	while ((void *)line < addr + len) {
+		switch(op) {
+		case OP_DCCIMVAC:
+			dccimvac(line);
+			break;
+		case OP_DCCMVAC:
+			dccmvac(line);
+			break;
+		case OP_DCIMVAC:
+			dcimvac(line);
+			break;
+		default:
+			break;
+		}
+		line += linesize;
+	}
+	isb();
+}
+
+void dcache_clean_by_mva(void const *addr, size_t len)
+{
+	dcache_op_mva(addr, len, OP_DCCMVAC);
+}
+
+void dcache_clean_invalidate_by_mva(void const *addr, size_t len)
+{
+	dcache_op_mva(addr, len, OP_DCCIMVAC);
+}
+
+void dcache_invalidate_by_mva(void const *addr, size_t len)
+{
+	dcache_op_mva(addr, len, OP_DCIMVAC);
+}
+
+void dcache_mmu_disable(void)
+{
+	uint32_t sctlr;
+
+	dcache_clean_invalidate_all();
+	sctlr = read_sctlr();
+	sctlr &= ~(SCTLR_C | SCTLR_M);
+	write_sctlr(sctlr);
+}
+
+
+void dcache_mmu_enable(void)
+{
+	uint32_t sctlr;
+
+	sctlr = read_sctlr();
+	dcache_clean_invalidate_all();
+	sctlr |= SCTLR_C | SCTLR_M;
+	write_sctlr(sctlr);
+}
+
+void arm_invalidate_caches(void)
+{
+	uint32_t clidr;
+	int level;
+
+	/* Invalidate branch predictor */
+	bpiall();
+
+	/* Iterate thru each cache identified in CLIDR and invalidate */
+	clidr = read_clidr();
+	for (level = 0; level < 7; level++) {
+		unsigned int ctype = (clidr >> (level * 3)) & 0x7;
+		uint32_t csselr;
+
+		switch(ctype) {
+		case 0x0:
+			/* no cache */
+			break;
+		case 0x1:
+			/* icache only */
+			csselr = (level << 1) | 1;
+			write_csselr(csselr);
+			icache_invalidate_all();
+			break;
+		case 0x2:
+		case 0x4:
+			/* dcache only or unified cache */
+			csselr = level << 1;
+			write_csselr(csselr);
+			dcache_invalidate_all();
+			break;
+		case 0x3:
+			/* separate icache and dcache */
+			csselr = (level << 1) | 1;
+			write_csselr(csselr);
+			icache_invalidate_all();
+
+			csselr = level << 1;
+			write_csselr(csselr);
+			dcache_invalidate_all();
+			break;
+		default:
+			/* reserved */
+			break;
+		}
+	}
+
+	/* Invalidate TLB */
+	tlb_invalidate_all();
+}
diff --git a/src/arch/arm/armv7/exception.c b/src/arch/arm/armv7/exception.c
new file mode 100644
index 0000000000..3b32e8bbb1
--- /dev/null
+++ b/src/arch/arm/armv7/exception.c
@@ -0,0 +1,180 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdint.h>
+#include <types.h>
+#include <arch/exception.h>
+#include <console/console.h>
+
+void exception_test(void);
+
+static int test_abort;
+
+void exception_undefined_instruction(uint32_t *);
+void exception_software_interrupt(uint32_t *);
+void exception_prefetch_abort(uint32_t *);
+void exception_data_abort(uint32_t *);
+void exception_not_used(uint32_t *);
+void exception_irq(uint32_t *);
+void exception_fiq(uint32_t *);
+
+static void dump_stack(uintptr_t addr, size_t bytes)
+{
+	int i, j;
+	const int line = 8;
+	uint32_t *ptr = (uint32_t *)(addr & ~(line * sizeof(*ptr) - 1));
+
+	printk(BIOS_ERR, "Dumping stack:\n");
+	for (i = bytes / sizeof(*ptr); i >= 0; i -= line) {
+		printk(BIOS_ERR, "%p: ", ptr + i);
+		for (j = i; j < i + line; j++)
+			printk(BIOS_ERR, "%08x ", *(ptr + j));
+		printk(BIOS_ERR, "\n");
+	}
+}
+
+static void print_regs(uint32_t *regs)
+{
+	int i;
+
+	for (i = 0; i < 16; i++) {
+		if (i == 15)
+			printk(BIOS_ERR, "PC");
+		else if (i == 14)
+			printk(BIOS_ERR, "LR");
+		else if (i == 13)
+			printk(BIOS_ERR, "SP");
+		else if (i == 12)
+			printk(BIOS_ERR, "IP");
+		else
+			printk(BIOS_ERR, "R%d", i);
+		printk(BIOS_ERR, " = 0x%08x\n", regs[i]);
+	}
+}
+
+void exception_undefined_instruction(uint32_t *regs)
+{
+	printk(BIOS_ERR, "exception _undefined_instruction\n");
+	print_regs(regs);
+	dump_stack(regs[13], 512);
+	die("exception");
+}
+
+void exception_software_interrupt(uint32_t *regs)
+{
+	printk(BIOS_ERR, "exception _software_interrupt\n");
+	print_regs(regs);
+	dump_stack(regs[13], 512);
+	die("exception");
+}
+
+void exception_prefetch_abort(uint32_t *regs)
+{
+	printk(BIOS_ERR, "exception _prefetch_abort\n");
+	print_regs(regs);
+	dump_stack(regs[13], 512);
+	die("exception");
+}
+
+void exception_data_abort(uint32_t *regs)
+{
+	if (test_abort) {
+		regs[15] = regs[0];
+		return;
+	} else {
+		printk(BIOS_ERR, "exception _data_abort\n");
+		print_regs(regs);
+		dump_stack(regs[13], 512);
+	}
+	die("exception");
+}
+
+void exception_not_used(uint32_t *regs)
+{
+	printk(BIOS_ERR, "exception _not_used\n");
+	print_regs(regs);
+	dump_stack(regs[13], 512);
+	die("exception");
+}
+
+void exception_irq(uint32_t *regs)
+{
+	printk(BIOS_ERR, "exception _irq\n");
+	print_regs(regs);
+	dump_stack(regs[13], 512);
+	die("exception");
+}
+
+void exception_fiq(uint32_t *regs)
+{
+	printk(BIOS_ERR, "exception _fiq\n");
+	print_regs(regs);
+	dump_stack(regs[13], 512);
+	die("exception");
+}
+
+static inline uint32_t get_sctlr(void)
+{
+	uint32_t val;
+	asm("mrc p15, 0, %0, c1, c0, 0" : "=r" (val));
+	return val;
+}
+
+static inline void set_sctlr(uint32_t val)
+{
+	asm volatile("mcr p15, 0, %0, c1, c0, 0" :: "r" (val));
+	asm volatile("" ::: "memory");
+}
+
+void exception_init(void)
+{
+	static const uint32_t sctlr_te = (0x1 << 30);
+	static const uint32_t sctlr_v = (0x1 << 13);
+	static const uint32_t sctlr_a = (0x1 << 1);
+
+	uint32_t sctlr = get_sctlr();
+	/* Handle exceptions in ARM mode. */
+	sctlr &= ~sctlr_te;
+	/* Set V=0 in SCTLR so VBAR points to the exception vector table. */
+	sctlr &= ~sctlr_v;
+	/* Enforce alignment temporarily. */
+	set_sctlr(sctlr | sctlr_a);
+
+	extern uint32_t exception_table[];
+	set_vbar((uintptr_t)exception_table);
+
+	test_abort = 1;
+	printk(BIOS_ERR, "Testing exceptions\n");
+	exception_test();
+	test_abort = 0;
+	printk(BIOS_ERR, "Testing exceptions: DONE\n");
+
+	/* Restore original alignment settings. */
+	set_sctlr(sctlr);
+}
diff --git a/src/arch/arm/armv7/exception_asm.S b/src/arch/arm/armv7/exception_asm.S
new file mode 100644
index 0000000000..163fdbd52a
--- /dev/null
+++ b/src/arch/arm/armv7/exception_asm.S
@@ -0,0 +1,116 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+exception_stack:
+	.align 5
+	.skip 0x2000, 0xa5
+exception_stack_end:
+	.word	exception_stack_end
+
+exception_handler:
+	.word 0
+
+
+	.align 6
+	.arm
+	.global exception_table
+exception_table:
+	b	1f
+	b	2f
+	b	3f
+	b	4f
+	b	5f
+	b	6f
+	b	7f
+	b	8f
+
+1:
+	ldr	sp, _not_used
+	b	exception_common
+2:
+	ldr	sp, _undefined_instruction
+	b	exception_common
+3:
+	ldr	sp, _software_interrupt
+	b	exception_common
+4:
+	ldr	sp, _prefetch_abort
+	b	exception_common
+5:
+	ldr	sp, _data_abort
+	b	exception_common
+6:
+	ldr	sp, _not_used
+	b	exception_common
+7:
+	ldr	sp, _irq
+	b	exception_common
+8:
+	ldr	sp, _fiq
+	b	exception_common
+
+exception_common:
+	str	sp, exception_handler
+	ldr	sp, exception_stack_end
+	push	{ lr }
+	stmfd	sp, { sp, lr }^
+	sub	sp, sp, $8
+	push	{ r0 - r12 }
+	mov	r0, sp
+	mov	lr, pc
+	ldr	pc, exception_handler
+	pop	{ r0 - r12 }
+	add	sp, sp, $8
+	ldmfd	sp!, { pc }^
+
+
+_undefined_instruction:	.word exception_undefined_instruction
+_software_interrupt:	.word exception_software_interrupt
+_prefetch_abort:	.word exception_prefetch_abort
+_data_abort:		.word exception_data_abort
+_not_used:		.word exception_not_used
+_irq:			.word exception_irq
+_fiq:			.word exception_fiq
+
+	.thumb
+	.global set_vbar
+	.thumb_func
+set_vbar:
+	mcr	p15, 0, r0, c12, c0, 0
+	bx	lr
+
+	.global exception_test
+	.thumb_func
+exception_test:
+	mov	r1, $1
+	mov	r0, pc
+	add	r0, $3
+	ldr	r1, [r1]
+	bx	lr
+
diff --git a/src/arch/arm/armv7/mmu.c b/src/arch/arm/armv7/mmu.c
new file mode 100644
index 0000000000..cc915a6a33
--- /dev/null
+++ b/src/arch/arm/armv7/mmu.c
@@ -0,0 +1,144 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include <cbmem.h>
+#include <console/console.h>
+
+#include <arch/cache.h>
+#include <arch/io.h>
+
+static void *const ttb_buff = (void *)CONFIG_TTB_BUFFER;
+
+void mmu_disable_range(unsigned long start_mb, unsigned long size_mb)
+{
+	unsigned int i;
+	uint32_t *ttb_entry = ttb_buff;
+	printk(BIOS_DEBUG, "Disabling: 0x%08lx:0x%08lx\n",
+			start_mb*MiB, start_mb*MiB + size_mb*MiB - 1);
+
+	for (i = start_mb; i < start_mb + size_mb; i++)
+		writel(0, &ttb_entry[i]);
+
+	for (i = start_mb; i < start_mb + size_mb; i++) {
+		dccmvac((uintptr_t)&ttb_entry[i]);
+		tlbimvaa(i*MiB);
+	}
+}
+
+void mmu_config_range(unsigned long start_mb, unsigned long size_mb,
+		enum dcache_policy policy)
+{
+	unsigned int i;
+	uint32_t attr;
+	uint32_t *ttb_entry = ttb_buff;
+	const char *str = NULL;
+
+	/*
+	 * Section entry bits:
+	 * 31:20 - section base address
+	 *    18 - 0 to indicate normal section (versus supersection)
+	 *    17 - nG, 0 to indicate page is global
+	 *    16 - S, 0 for non-shareable (?)
+	 *    15 - APX, 0 for full access
+	 * 14:12 - TEX, 0b000 for outer and inner write-back
+	 * 11:10 - AP, 0b11 for full access
+	 *     9 - P, ? (FIXME: not described or possibly obsolete?)
+	 *  8: 5 - Domain
+	 *     4 - XN, 1 to set execute-never (and also avoid prefetches)
+	 *     3 - C, 1 for cacheable
+	 *     2 - B, 1 for bufferable
+	 *  1: 0 - 0b10 to indicate section entry
+	 */
+
+	switch(policy) {
+	case DCACHE_OFF:
+		/* XN set to avoid prefetches to uncached/unbuffered regions */
+		attr = (0x3 << 10) | (1 << 4) | 0x2;
+		str = "off";
+		break;
+	case DCACHE_WRITEBACK:
+		attr =  (0x3 << 10) | (1 << 3) | (1 << 2) | 0x2;
+		str = "writeback";
+		break;
+	case DCACHE_WRITETHROUGH:
+		attr =  (0x3 << 10) | (1 << 3) | 0x2;
+		str = "writethrough";
+		break;
+	default:
+		printk(BIOS_ERR, "unknown dcache policy: %02x\n", policy);
+		return;
+	}
+
+	printk(BIOS_DEBUG, "Setting dcache policy: 0x%08lx:0x%08lx [%s]\n",
+			start_mb << 20, ((start_mb + size_mb) << 20) - 1, str);
+
+	/* Write out page table entries. */
+	for (i = start_mb; i < start_mb + size_mb; i++)
+		writel((i << 20) | attr, &ttb_entry[i]);
+
+	/* Flush the page table entries, and old translations from the TLB. */
+	for (i = start_mb; i < start_mb + size_mb; i++) {
+		dccmvac((uintptr_t)&ttb_entry[i]);
+		tlbimvaa(i*MiB);
+	}
+}
+
+void mmu_init(void)
+{
+	/*
+	 * For coreboot's purposes, we will create a simple L1 page table
+	 * in RAM with 1MB section translation entries over the 4GB address
+	 * space.
+	 * (ref: section 10.2 and example 15-4 in Cortex-A series
+	 * programmer's guide)
+         */
+	printk(BIOS_DEBUG, "Translation table is @ %p\n", ttb_buff);
+
+	/*
+	 * Disable TTBR1 by setting TTBCR.N to 0b000, which means the TTBR0
+	 * table size is 16KB and has indices VA[31:20].
+	 *
+	 * ref: Arch Ref. Manual for ARMv7-A, B3.5.4,
+	 */
+	write_ttbcr(read_ttbcr() & ~0x3);
+
+	/*
+	 * Translation table base 0 address is in bits 31:14-N, where N is given
+	 * by bits 2:0 in TTBCR (which we set to 0). All lower bits in this
+	 * register should be zero for coreboot.
+	 */
+	write_ttbr0((uintptr_t)ttb_buff);
+
+	/* disable domain-level checking of permissions */
+	write_dacr(~0);
+}
diff --git a/src/arch/arm/armv7/thread.c b/src/arch/arm/armv7/thread.c
new file mode 100644
index 0000000000..d0c23ff92d
--- /dev/null
+++ b/src/arch/arm/armv7/thread.c
@@ -0,0 +1,127 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <console/console.h>
+#include <thread.h>
+
+/* The stack frame looks like the following. */
+struct pushed_regs {
+	u32 r4;
+	u32 r5;
+	u32 r6;
+	u32 r7;
+	u32 r8;
+	u32 r9;
+	u32 r10;
+	u32 r11;
+	u32 lr;
+};
+
+static inline uintptr_t push_stack(uintptr_t cur_stack, uintptr_t value)
+{
+	uintptr_t *addr;
+
+	cur_stack -= sizeof(value);
+	addr = (uintptr_t *)cur_stack;
+	*addr = value;
+	return cur_stack;
+}
+
+void arch_prepare_thread(struct thread *t,
+                         void asmlinkage (*thread_entry)(void *), void *arg)
+{
+	uintptr_t stack = t->stack_current;
+	int i;
+	uintptr_t poison = 0xdeadbeef;
+
+	/* Push the LR. thread_entry()
+	 * is assumed to never return.
+	 */
+	stack = push_stack(stack, (uintptr_t)thread_entry);
+	/* Make room for the registers.
+	 * Poison the initial stack. This is good hygiene and finds bugs.
+	 * Poisoning the stack with different values helps when you're
+	 * hunting for (e.g.) misaligned stacks or other such
+	 * weirdness. The -1 is because we already pushed lr.
+	 */
+	for(i = 0; i < sizeof(struct pushed_regs)/sizeof(u32)-1; i++)
+		stack = push_stack(stack, poison++);
+
+	t->stack_current = stack;
+}
+
+/* We could write this as a .S and the first time around that's how we
+ * did it. But there's always the question of matching our ARM
+ * directives in the .S with how gcc is doing things.  It seems best
+ * to follow the pattern of the rest of the ARM port and just use
+ * inline assembly and let gcc get all the ELF magic right.
+ */
+void __attribute__((naked))
+switch_to_thread(uintptr_t new_stack, uintptr_t *saved_stack)
+{
+	/* Defintions for those of us not totally familiar with ARM:
+	 * R15 -- PC, R14 -- LR, R13 -- SP
+	 * R0-R3 need not be saved, nor R12.
+	 * on entry, the only saved state is in LR -- the old PC.
+	 * The args are in R0,R1.
+	 * R0 is the new stack
+	 * R1 is a pointer to the old stack save location
+	 * Push R4-R11 and LR
+	 * then switch stacks
+	 * then pop R0-R12 and LR
+	 * then mov PC,LR
+	 *
+	 * stack layout
+	 * +------------+
+	 * |    LR      | <-- sp + 0x20
+	 * +------------+
+	 * |    R11     | <-- sp + 0x1c
+	 * +------------+
+	 * |    R10     | <-- sp + 0x18
+	 * +------------+
+	 * |    R9      | <-- sp + 0x14
+	 * +------------+
+	 * |    R8      | <-- sp + 0x10
+	 * +------------+
+	 * |    R7      | <-- sp + 0x0c
+	 * +------------+
+	 * |    R6      | <-- sp + 0x08
+	 * +------------+
+	 * |    R5      | <-- sp + 0x04
+	 * +------------+
+	 * |    R4      | <-- sp + 0x00
+	 * +------------+
+	 */
+        asm volatile (
+	/* save context. */
+	"push {r4-r11,lr}\n\t"
+	/* Save the current stack */
+	"str sp,[r1]\n\t"
+	/* switch to the new stack */
+	"mov sp,r0\n\t"
+	/* restore the registers */
+	"pop {r4-r11,lr}\n\t"
+	/* resume other thread. */
+	"mov pc,lr\n\t"
+	);
+}
+
+void *arch_get_thread_stackbase(void)
+{
+	return (void *)CONFIG_STACK_BOTTOM;
+}