Add code necessary for correct initialization of exception vector
table when MMU is disabled.
Note: Please be aware that non ARMv7 implementation of this
functionality was not fully tested due to the lack of any such
hardware. It should theoretically work, but only testing that I did
was to test place_vector_table() failure path (the best I could do on
a i.MX6)
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
arch/arm/cpu/Makefile | 6 +++
arch/arm/cpu/no-mmu.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+)
create mode 100644 arch/arm/cpu/no-mmu.c
diff --git a/arch/arm/cpu/Makefile b/arch/arm/cpu/Makefile
index 418bcab..f708e8f 100644
--- a/arch/arm/cpu/Makefile
+++ b/arch/arm/cpu/Makefile
@@ -11,6 +11,12 @@ obj-$(CONFIG_CMD_ARM_MMUINFO) += mmuinfo.o
obj-$(CONFIG_OFDEVICE) += dtb.o
obj-$(CONFIG_MMU) += mmu.o cache.o mmu-early.o
pbl-$(CONFIG_MMU) += mmu-early.o
+
+ifeq ($(CONFIG_MMU),)
+obj-y += no-mmu.o
+pbl-y += no-mmu.o
+endif
+
obj-$(CONFIG_CPU_32v4T) += cache-armv4.o
pbl-$(CONFIG_CPU_32v4T) += cache-armv4.o
obj-$(CONFIG_CPU_32v5) += cache-armv5.o
diff --git a/arch/arm/cpu/no-mmu.c b/arch/arm/cpu/no-mmu.c
new file mode 100644
index 0000000..591cc2c
--- /dev/null
+++ b/arch/arm/cpu/no-mmu.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2015 Zodiac Inflight Innovation
+ * Author: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
+ *
+ * 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.
+ *
+ */
+
+#define pr_fmt(fmt) "nommu: " fmt
+
+#include <common.h>
+#include <dma-dir.h>
+#include <init.h>
+#include <mmu.h>
+#include <errno.h>
+#include <linux/sizes.h>
+#include <asm/memory.h>
+#include <asm/barebox-arm.h>
+#include <asm/system.h>
+#include <asm/cache.h>
+#include <memory.h>
+#include <asm/system_info.h>
+#include <debug_ll.h>
+
+
+#define __exceptions_size (__exceptions_stop - __exceptions_start)
+
+#if __LINUX_ARM_ARCH__ >= 7
+
+static int nommu_v7_vectors_init(void)
+{
+ void *vectors;
+ u32 cr;
+
+ /*
+ High vectors cannot be re-mapped, so we have to use normal
+ vectors
+ */
+ cr = get_cr();
+ cr &= ~CR_V;
+ set_cr(cr);
+
+ arm_fixup_vectors();
+
+ vectors = xmemalign(PAGE_SIZE, PAGE_SIZE);
+ memset(vectors, 0, PAGE_SIZE);
+ memcpy(vectors, __exceptions_start, __exceptions_size);
+
+ set_vbar((unsigned int)vectors);
+
+ return 0;
+}
+mmu_initcall(nommu_v7_vectors_init);
+
+#else
+
+#warning "This code has seen only rudimentary testing (only failure path). Proceed with caution"
+
+static struct resource *place_vector_table(void)
+{
+ int i;
+ struct resource *vectors = NULL;
+ resource_size_t addr[2] = { 0x00000000, 0xFFFF0000 };
+
+ for (i = 0; i < ARRAY_SIZE(addr); i++) {
+ vectors = request_sdram_region("exceptions",
+ addr[i],
+ __exceptions_size);
+ if (vectors)
+ break;
+ }
+
+ return vectors;
+}
+
+static int nommu_v4_vectors_init(void)
+{
+ u32 cr;
+ struct resource *vectors;
+
+ vectors = place_vector_table();
+ if (!vectors) {
+ pr_crit("Critical Error: Can't place exception vector table\n");
+ return 0;
+ }
+
+ cr = get_cr();
+
+ if (vectors->start) {
+ cr |= CR_V;
+ set_cr(cr);
+
+ if (!(get_cr() & CR_V)) {
+ pr_crit("Critical Error: "
+ "High vector table is unavailble\n");
+ release_sdram_region(vectors);
+ return 0;
+ }
+ } else {
+ cr &= ~CR_V;
+ set_cr(cr);
+ }
+
+ arm_fixup_vectors();
+
+ memcpy((void *)vectors->start,
+ __exceptions_start, resource_size(vectors));
+
+ return 0;
+}
+mmu_initcall(nommu_v4_vectors_init);
+
+#endif
--
2.5.0
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