[U-Boot] [RFC 1/1] ARM: Add ARMv7-M support
rev13 at wp.pl
rev13 at wp.pl
Wed Jan 7 00:57:27 CET 2015
From: Kamil Lulko <rev13 at wp.pl>
I am working on STM32F429-Discovery board support for U-Boot. This is a low-cost and fun board boasting LCD screen, bells and whistles for just under 24$. This board seems to be popular in commercial environments for evaluating ARM in deeply embedded applications. I would like to add support for this board in the mainline U-Boot but "new" architecture support is needed first (ARMv7-M variant is slightly different from other ARMs). This patch implements basic architecture support which I am already using for my own Linux booting setup with this board. I would really appreciate your opinion on feasibility of this board in mainline U-Boot tree and correctness (or not) of this patch. I tried to re-use as much as possible from existing ARM code.
Signed-off-by: Kamil Lulko <rev13 at wp.pl>
---
arch/arm/cpu/armv7m/Makefile | 9 ++++
arch/arm/cpu/armv7m/config.mk | 8 ++++
arch/arm/cpu/armv7m/cpu.c | 51 +++++++++++++++++++++++
arch/arm/cpu/armv7m/start.S | 18 ++++++++
arch/arm/include/asm/armv7m.h | 60 +++++++++++++++++++++++++++
arch/arm/lib/Makefile | 8 ++++
arch/arm/lib/crt0.S | 33 +++++++++++++++
arch/arm/lib/interrupts_m.c | 95 +++++++++++++++++++++++++++++++++++++++++++
arch/arm/lib/relocate.S | 4 ++
arch/arm/lib/vectors_m.S | 58 ++++++++++++++++++++++++++
10 files changed, 344 insertions(+)
create mode 100644 arch/arm/cpu/armv7m/Makefile
create mode 100644 arch/arm/cpu/armv7m/config.mk
create mode 100644 arch/arm/cpu/armv7m/cpu.c
create mode 100644 arch/arm/cpu/armv7m/start.S
create mode 100644 arch/arm/include/asm/armv7m.h
create mode 100644 arch/arm/lib/interrupts_m.c
create mode 100644 arch/arm/lib/vectors_m.S
diff --git a/arch/arm/cpu/armv7m/Makefile b/arch/arm/cpu/armv7m/Makefile
new file mode 100644
index 0000000..3279f12
--- /dev/null
+++ b/arch/arm/cpu/armv7m/Makefile
@@ -0,0 +1,9 @@
+#
+# (C) Copyright 2000-2006
+# Wolfgang Denk, DENX Software Engineering, wd at denx.de.
+#
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+extra-y = start.o
+obj-y = cpu.o
diff --git a/arch/arm/cpu/armv7m/config.mk b/arch/arm/cpu/armv7m/config.mk
new file mode 100644
index 0000000..37cfff9
--- /dev/null
+++ b/arch/arm/cpu/armv7m/config.mk
@@ -0,0 +1,8 @@
+#
+# (C) Copyright 2014
+# Kamil Lulko, <rev13 at wp.pl>
+#
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+PLATFORM_CPPFLAGS += -march=armv7-m -mthumb
diff --git a/arch/arm/cpu/armv7m/cpu.c b/arch/arm/cpu/armv7m/cpu.c
new file mode 100644
index 0000000..ee4240a
--- /dev/null
+++ b/arch/arm/cpu/armv7m/cpu.c
@@ -0,0 +1,51 @@
+/*
+ * (C) Copyright 2010,2011
+ * Vladimir Khusainov, Emcraft Systems, vlad at emcraft.com
+ *
+ * (C) Copyright 2014
+ * Kamil Lulko, <rev13 at wp.pl>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <asm/armv7m.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * This is called right before passing control to
+ * the Linux kernel point.
+ */
+int cleanup_before_linux(void)
+{
+ return 0;
+}
+
+/*
+ * H/w WDT strobe routine
+ */
+#if defined (CONFIG_HW_WATCHDOG)
+void hw_watchdog_reset(void)
+{
+ /*
+ * Call the h/w-specific WDT strobe.
+ */
+ wdt_strobe();
+}
+#endif
+
+/*
+ * Perform the low-level reset.
+ */
+void reset_cpu(ulong addr)
+{
+ /*
+ * Perform reset but keep priority group unchanged.
+ */
+ V7M_SCB->aircr = (V7M_AIRCR_VECTKEY << V7M_AIRCR_VECTKEY_SHIFT) |
+ (V7M_SCB->aircr &
+ (V7M_AIRCR_PRIGROUP_MSK << V7M_AIRCR_PRIGROUP_SHIFT))
+ | V7M_AIRCR_SYSRESET;
+}
diff --git a/arch/arm/cpu/armv7m/start.S b/arch/arm/cpu/armv7m/start.S
new file mode 100644
index 0000000..730c775
--- /dev/null
+++ b/arch/arm/cpu/armv7m/start.S
@@ -0,0 +1,18 @@
+/*
+ * (C) Copyright 2014
+ * Kamil Lulko, <rev13 at wp.pl>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <config.h>
+#include <linux/linkage.h>
+
+.globl reset
+.type reset, %function
+reset:
+ bl _main
+
+.globl c_runtime_cpu_setup
+c_runtime_cpu_setup:
+ mov pc, lr
diff --git a/arch/arm/include/asm/armv7m.h b/arch/arm/include/asm/armv7m.h
new file mode 100644
index 0000000..786ce3c
--- /dev/null
+++ b/arch/arm/include/asm/armv7m.h
@@ -0,0 +1,60 @@
+/*
+ * (C) Copyright 2010,2011
+ * Vladimir Khusainov, Emcraft Systems, vlad at emcraft.com
+ *
+ * (C) Copyright 2014
+ * Kamil Lulko, <rev13 at wp.pl>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef ARMV7M_H
+#define ARMV7M_H
+
+#if defined(__ASSEMBLY__)
+.syntax unified
+.thumb
+#endif
+
+#define V7M_SCB_BASE 0xE000ED00
+#define V7M_MPU_BASE 0xE000ED90
+
+#if !defined(__ASSEMBLY__)
+struct v7m_scb {
+ uint32_t cpuid; /* CPUID Base Register */
+ uint32_t icsr; /* Interrupt Control and State Register */
+ uint32_t vtor; /* Vector Table Offset Register */
+ uint32_t aircr; /* App Interrupt and Reset Control Register */
+};
+#define V7M_SCB ((volatile struct v7m_scb *)V7M_SCB_BASE)
+
+#define V7M_AIRCR_VECTKEY 0x5fa
+#define V7M_AIRCR_VECTKEY_SHIFT 16
+#define V7M_AIRCR_ENDIAN (1 << 15)
+#define V7M_AIRCR_PRIGROUP_MSK 0x7
+#define V7M_AIRCR_PRIGROUP_SHIFT 8
+#define V7M_AIRCR_SYSRESET (1 << 2)
+
+#define V7M_ICSR_VECTACT_MSK 0xFF
+
+struct v7m_mpu {
+ uint32_t type; /* Type Register */
+ uint32_t ctrl; /* Control Register */
+ uint32_t rnr; /* Region Number Register */
+ uint32_t rbar; /* Region Base Address Register */
+ uint32_t rasr; /* Region Attribute and Size Register */
+};
+#define V7M_MPU ((volatile struct v7m_mpu *)V7M_MPU_BASE)
+
+#define V7M_MPU_CTRL_ENABLE (1 << 0)
+#define V7M_MPU_CTRL_HFNMIENA (1 << 1)
+
+#define V7M_MPU_RASR_EN (1 << 0)
+
+#define V7M_MPU_RASR_SIZE_BITS 1
+#define V7M_MPU_RASR_SIZE_4GB (31 << V7M_MPU_RASR_SIZE_BITS)
+#define V7M_MPU_RASR_AP_RW_RW (3 << 24)
+
+#endif
+
+#endif /* ARMV7M_H */
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index d74e4b8..dd3afb8 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -8,11 +8,15 @@
lib-$(CONFIG_USE_PRIVATE_LIBGCC) += _ashldi3.o _ashrdi3.o _divsi3.o \
_lshrdi3.o _modsi3.o _udivsi3.o _umodsi3.o div0.o
+ifdef CONFIG_ARMV7M
+obj-y += vectors_m.o crt0.o
+else
ifdef CONFIG_ARM64
obj-y += crt0_64.o
else
obj-y += vectors.o crt0.o
endif
+endif
ifndef CONFIG_SPL_BUILD
ifdef CONFIG_ARM64
@@ -35,12 +39,16 @@ endif
obj-$(CONFIG_SEMIHOSTING) += semihosting.o
obj-y += sections.o
+ifdef CONFIG_ARMV7M
+obj-y += interrupts_m.o
+else
ifdef CONFIG_ARM64
obj-y += gic_64.o
obj-y += interrupts_64.o
else
obj-y += interrupts.o
endif
+endif
obj-y += reset.o
obj-y += cache.o
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
index 22df3e5..21e05e6 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -9,6 +9,9 @@
#include <config.h>
#include <asm-offsets.h>
#include <linux/linkage.h>
+#if defined(CONFIG_ARMV7M)
+#include <asm/armv7m.h>
+#endif
/*
* This file handles the target-independent stages of the U-Boot
@@ -66,15 +69,32 @@ ENTRY(_main)
#else
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
#endif
+#if defined(CONFIG_ARMV7M)
+ /* 8-byte alignment for ABI compliance armv7-m version */
+ mov r3, sp
+ bic r3, r3, #7
+ mov sp, r3
+#else
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
+#endif
mov r2, sp
sub sp, sp, #GD_SIZE /* allocate one GD above SP */
+#if defined(CONFIG_ARMV7M)
+ /* 8-byte alignment for ABI compliance armv7-m version */
+ mov r3, sp
+ bic r3, r3, #7
+ mov sp, r3
+#else
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
+#endif
mov r9, sp /* GD is above SP */
mov r1, sp
mov r0, #0
clr_gd:
cmp r1, r2 /* while not at end of GD */
+#if defined(CONFIG_ARMV7M)
+ itt lo
+#endif
strlo r0, [r1] /* clear 32-bit GD word */
addlo r1, r1, #4 /* move to next */
blo clr_gd
@@ -94,13 +114,23 @@ clr_gd:
*/
ldr sp, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
+#if defined(CONFIG_ARMV7M)
+ /* 8-byte alignment for ABI compliance armv7-m version */
+ mov r3, sp
+ bic r3, r3, #7
+ mov sp, r3
+#else
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
+#endif
ldr r9, [r9, #GD_BD] /* r9 = gd->bd */
sub r9, r9, #GD_SIZE /* new GD is below bd */
adr lr, here
ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */
add lr, lr, r0
+#if defined(CONFIG_ARMV7M)
+ orr lr, #1 /* Set bit 0 as required by Thumb-2 */
+#endif
ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
b relocate_code
here:
@@ -120,6 +150,9 @@ here:
mov r2, #0x00000000 /* prepare zero to clear BSS */
clbss_l:cmp r0, r1 /* while not at end of BSS */
+#if defined(CONFIG_ARMV7M)
+ itt lo
+#endif
strlo r2, [r0] /* clear 32-bit BSS word */
addlo r0, r0, #4 /* move to next */
blo clbss_l
diff --git a/arch/arm/lib/interrupts_m.c b/arch/arm/lib/interrupts_m.c
new file mode 100644
index 0000000..0d7e891
--- /dev/null
+++ b/arch/arm/lib/interrupts_m.c
@@ -0,0 +1,95 @@
+/*
+ * (C) Copyright 2014
+ * Kamil Lulko, <rev13 at wp.pl>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+
+/*
+ * Upon exception entry ARMv7-M processors automatically save stack
+ * frames containing some registers. For simplicity initial
+ * implementation uses only this auto-saved stack frame.
+ * This does not contain complete register set dump,
+ * only R0-R3, R12, LR, PC and xPSR are saved.
+ */
+
+struct autosave_regs {
+ long uregs[8];
+};
+
+#define ARM_xPSR uregs[7]
+#define ARM_PC uregs[6]
+#define ARM_LR uregs[5]
+#define ARM_R12 uregs[4]
+#define ARM_R3 uregs[3]
+#define ARM_R2 uregs[2]
+#define ARM_R1 uregs[1]
+#define ARM_R0 uregs[0]
+
+int interrupt_init(void)
+{
+ return 0;
+}
+
+void enable_interrupts(void)
+{
+ return;
+}
+
+int disable_interrupts(void)
+{
+ return 0;
+}
+
+void dump_regs(struct autosave_regs *regs)
+{
+ printf("pc : %08lx lr : %08lx xPSR : %08lx\n",
+ regs->ARM_PC, regs->ARM_LR, regs->ARM_xPSR);
+ printf("r12 : %08lx r3 : %08lx r2 : %08lx\n"
+ "r1 : %08lx r0 : %08lx\n",
+ regs->ARM_R12, regs->ARM_R3, regs->ARM_R2,
+ regs->ARM_R1, regs->ARM_R0);
+}
+
+void bad_mode(void)
+{
+ panic("Resetting CPU ...\n");
+ reset_cpu(0);
+}
+
+void do_hard_fault(struct autosave_regs *autosave_regs)
+{
+ printf("Hard fault\n");
+ dump_regs(autosave_regs);
+ bad_mode();
+}
+
+void do_mm_fault(struct autosave_regs *autosave_regs)
+{
+ printf("Memory management fault\n");
+ dump_regs(autosave_regs);
+ bad_mode();
+}
+
+void do_bus_fault(struct autosave_regs *autosave_regs)
+{
+ printf("Bus fault\n");
+ dump_regs(autosave_regs);
+ bad_mode();
+}
+
+void do_usage_fault(struct autosave_regs *autosave_regs)
+{
+ printf("Usage fault\n");
+ dump_regs(autosave_regs);
+ bad_mode();
+}
+
+void do_invalid_entry(struct autosave_regs *autosave_regs)
+{
+ printf("Exception\n");
+ dump_regs(autosave_regs);
+ bad_mode();
+}
diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
index 92f5314..ef2a274 100644
--- a/arch/arm/lib/relocate.S
+++ b/arch/arm/lib/relocate.S
@@ -9,6 +9,10 @@
#include <asm-offsets.h>
#include <config.h>
#include <linux/linkage.h>
+#include <config.h>
+#if defined(CONFIG_ARMV7M)
+#include <asm/armv7m.h>
+#endif
/*
* Default/weak exception vectors relocation routine
diff --git a/arch/arm/lib/vectors_m.S b/arch/arm/lib/vectors_m.S
new file mode 100644
index 0000000..20a4527
--- /dev/null
+++ b/arch/arm/lib/vectors_m.S
@@ -0,0 +1,58 @@
+/*
+ * (C) Copyright 2014
+ * Kamil Lulko, <rev13 at wp.pl>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <config.h>
+#include <asm/armv7m.h>
+#include <linux/linkage.h>
+
+.type __hard_fault_entry, %function
+__hard_fault_entry:
+ mov r0, sp @ pass auto-saved registers as argument
+ b do_hard_fault
+
+.type __mm_fault_entry, %function
+__mm_fault_entry:
+ mov r0, sp @ pass auto-saved registers as argument
+ b do_mm_fault
+
+.type __bus_fault_entry, %function
+__bus_fault_entry:
+ mov r0, sp @ pass auto-saved registers as argument
+ b do_bus_fault
+
+.type __usage_fault_entry, %function
+__usage_fault_entry:
+ mov r0, sp @ pass auto-saved registers as argument
+ b do_usage_fault
+
+.type __invalid_entry, %function
+__invalid_entry:
+ mov r0, sp @ pass auto-saved registers as argument
+ b do_invalid_entry
+
+ .section .vectors
+
+ENTRY(_start)
+ .long CONFIG_SYS_INIT_SP_ADDR @ 0 - Reset stack pointer
+ .long reset @ 1 - Reset
+ .long __invalid_entry @ 2 - NMI
+ .long __hard_fault_entry @ 3 - HardFault
+ .long __mm_fault_entry @ 4 - MemManage
+ .long __bus_fault_entry @ 5 - BusFault
+ .long __usage_fault_entry @ 6 - UsageFault
+ .long __invalid_entry @ 7 - Reserved
+ .long __invalid_entry @ 8 - Reserved
+ .long __invalid_entry @ 9 - Reserved
+ .long __invalid_entry @ 10 - Reserved
+ .long __invalid_entry @ 11 - SVCall
+ .long __invalid_entry @ 12 - Debug Monitor
+ .long __invalid_entry @ 13 - Reserved
+ .long __invalid_entry @ 14 - PendSV
+ .long __invalid_entry @ 15 - SysTick
+ .rept 107 - 16
+ .long __invalid_entry @ 16..107 - External Interrupts
+ .endr
--
2.2.1.212.gc5b9256
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