[PATCH v2 2/9] lpc2k: Exception vector handling

[ithamar.adema@team-embedded.nl (Ithamar R. Adema)]

Since the LPC2K does not have an MMU (ARM7TDMI based), it expects the vectors to be
stored in on-chip SRAM. However, this moves the vectors too far away from the stubs
page, requiring the vector jumps to be indirect.

Since now VECTOR_BASE is below PHYS_OFFSET, do not try to reserve the vector
page, as it will fail (and prevent the kernel from booting).

Also, commit 247055aa (6384/1: Remove the domain switching on ARMv6k/v7 CPUs) broke
the placement of vectors in the !MMU case, so fix this too.

Signed-off-by: Ithamar R. Adema <ithamar.adema@team-embedded.nl>
---
changes since v1:
	* added comment to entry-armv.S vector #ifdef.
---
 arch/arm/Kconfig             |    1 +
 arch/arm/kernel/entry-armv.S |   24 ++++++++++++++++++++++++
 arch/arm/kernel/traps.c      |    2 +-
 arch/arm/mm/nommu.c          |    2 ++
 4 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8129cbc..99afdeb 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -186,6 +186,7 @@ config VECTORS_BASE
 	hex
 	default 0xffff0000 if MMU || CPU_HIGH_VECTOR
 	default DRAM_BASE if REMAP_VECTORS_TO_RAM
+	default 0x40000000 if ARCH_LPC2K
 	default 0x00000000
 	help
 	  The base address of exception vectors.
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index e8d8856..44686b0 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -1208,6 +1208,7 @@ __stubs_end:
 
 	.globl	__vectors_start
 __vectors_start:
+#ifndef CONFIG_ARCH_LPC2K
  ARM(	swi	SYS_ERROR0	)
  THUMB(	svc	#0		)
  THUMB(	nop			)
@@ -1218,6 +1219,29 @@ __vectors_start:
 	W(b)	vector_addrexcptn + stubs_offset
 	W(b)	vector_irq + stubs_offset
 	W(b)	vector_fiq + stubs_offset
+#else /* CONFIG_ARCH_LPC2K */
+	/*
+	 * The LPC2K does not have an MMU (ARM7TDMI based), it expects
+	 * the vectors to be stored in on-chip SRAM. This moves the
+	 * vectors too far away from the stubs page, so requiring the
+	 * vector jumps to be indirect.
+	 */
+	swi	SYS_ERROR0
+	ldr	pc, .vector_und
+	ldr	pc, .vector_swi
+	ldr	pc, .vector_pabt
+	ldr	pc, .vector_dabt
+	ldr	pc, .vector_addrexcptn
+	ldr	pc, .vector_irq
+	ldr	pc, .vector_fiq
+.vector_und:		.word   vector_und
+.vector_swi:		.word   vector_swi
+.vector_pabt:		.word   vector_pabt
+.vector_dabt:		.word   vector_dabt
+.vector_addrexcptn:	.word   vector_addrexcptn
+.vector_irq:		.word   vector_irq
+.vector_fiq:		.word   vector_fiq
+#endif
 
 	.globl	__vectors_end
 __vectors_end:
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 21ac43f..639c4c8 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -758,7 +758,7 @@ static void __init kuser_get_tls_init(unsigned long vectors)
 
 void __init early_trap_init(void)
 {
-#if defined(CONFIG_CPU_USE_DOMAINS)
+#if defined(CONFIG_CPU_USE_DOMAINS) || !defined(CONFIG_MMU)
 	unsigned long vectors = CONFIG_VECTORS_BASE;
 #else
 	unsigned long vectors = (unsigned long)vectors_page;
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index 687d023..e3bec02 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -24,7 +24,9 @@ void __init arm_mm_memblock_reserve(void)
 	 * some architectures which the DRAM is the exception vector to trap,
 	 * alloc_page breaks with error, although it is not NULL, but "0."
 	 */
+#if PHYS_OFFSET <= CONFIG_VECTORS_BASE
 	memblock_reserve(CONFIG_VECTORS_BASE, PAGE_SIZE);
+#endif
 }
 
 /*
-- 
1.7.1