Since the reset vector is always aligned to a very large boundary, we can save a couple of KB worth of alignment padding by placing the exception vectors at the same address.
Deciding which one it is is easy: If we're handling an exception, the CPU is in Exception mode. If we're starting up after reset, the CPU is in Supervisor mode. So this adds a very minimal overhead to the reset path (only executed once) and the exception handling path (normally never executed at all.)
Signed-off-by: Haavard Skinnemoen haavard.skinnemoen@atmel.com --- board/atmel/atngw100/u-boot.lds | 1 + board/atmel/atstk1000/u-boot.lds | 1 + cpu/at32ap/Makefile | 1 - cpu/at32ap/entry.S | 64 ------------------- cpu/at32ap/start.S | 129 +++++++++++++++++++++++++++++++++++--- 5 files changed, 122 insertions(+), 74 deletions(-) delete mode 100644 cpu/at32ap/entry.S
diff --git a/board/atmel/atngw100/u-boot.lds b/board/atmel/atngw100/u-boot.lds index 3c878d8..e736adf 100644 --- a/board/atmel/atngw100/u-boot.lds +++ b/board/atmel/atngw100/u-boot.lds @@ -29,6 +29,7 @@ SECTIONS . = 0; _text = .; .text : { + *(.exception.text) *(.text) *(.text.*) } diff --git a/board/atmel/atstk1000/u-boot.lds b/board/atmel/atstk1000/u-boot.lds index f63bc4f..0d3b19c 100644 --- a/board/atmel/atstk1000/u-boot.lds +++ b/board/atmel/atstk1000/u-boot.lds @@ -29,6 +29,7 @@ SECTIONS . = 0; _text = .; .text : { + *(.exception.text) *(.text) *(.text.*) } diff --git a/cpu/at32ap/Makefile b/cpu/at32ap/Makefile index 8e384c7..29f9c0d 100644 --- a/cpu/at32ap/Makefile +++ b/cpu/at32ap/Makefile @@ -29,7 +29,6 @@ LIB := $(obj)lib$(CPU).a
START-y += start.o
-SOBJS-y += entry.o COBJS-y += cpu.o COBJS-y += hsdramc.o COBJS-y += exception.o diff --git a/cpu/at32ap/entry.S b/cpu/at32ap/entry.S deleted file mode 100644 index a6fc688..0000000 --- a/cpu/at32ap/entry.S +++ /dev/null @@ -1,64 +0,0 @@ -/* - * Copyright (C) 2004-2006 Atmel Corporation - * - * See file CREDITS for list of people who contributed to this - * project. - * - * 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; either version 2 of - * the License, or (at your option) any later version. - * - * 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 - */ -#include <asm/sysreg.h> -#include <asm/ptrace.h> - - .section .text.exception,"ax" - .global _evba - .type _evba,@function - .align 10 -_evba: - .irp x,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 - .align 2 - rjmp unknown_exception - .endr - - .global timer_interrupt_handler - .type timer_interrupt_handler,@function - .align 2 -timer_interrupt_handler: - /* - * Increment timer_overflow and re-write COMPARE with 0xffffffff. - * - * We're running at interrupt level 3, so we don't need to save - * r8-r12 or lr to the stack. - */ - lda.w r8, timer_overflow - ld.w r9, r8[0] - mov r10, -1 - mtsr SYSREG_COMPARE, r10 - sub r9, -1 - st.w r8[0], r9 - rete - - .type unknown_exception, @function -unknown_exception: - pushm r0-r12 - sub r8, sp, REG_R12 - REG_R0 - 4 - mov r9, lr - mfsr r10, SYSREG_RAR_EX - mfsr r11, SYSREG_RSR_EX - pushm r8-r11 - mfsr r12, SYSREG_ECR - mov r11, sp - rcall do_unknown_exception -1: rjmp 1b diff --git a/cpu/at32ap/start.S b/cpu/at32ap/start.S index ab8c2b7..907e9b1 100644 --- a/cpu/at32ap/start.S +++ b/cpu/at32ap/start.S @@ -1,5 +1,5 @@ /* - * Copyright (C) 2005-2006 Atmel Corporation + * Copyright (C) 2005-2008 Atmel Corporation * * See file CREDITS for list of people who contributed to this * project. @@ -20,12 +20,9 @@ * MA 02111-1307 USA */ #include <config.h> +#include <asm/ptrace.h> #include <asm/sysreg.h>
-#ifndef PART_SPECIFIC_BOOTSTRAP -# define PART_SPECIFIC_BOOTSTRAP -#endif - #define SYSREG_MMUCR_I_OFFSET 2 #define SYSREG_MMUCR_S_OFFSET 4
@@ -34,11 +31,115 @@ | SYSREG_BIT(FE) | SYSREG_BIT(RE) \ | SYSREG_BIT(IBE) | SYSREG_BIT(IEE))
- .text + /* + * To save some space, we use the same entry point for + * exceptions and reset. This avoids lots of alignment padding + * since the reset vector is always suitably aligned. + */ + .section .exception.text, "ax", @progbits .global _start + .global _evba + .type _start, @function + .type _evba, @function _start: - PART_SPECIFIC_BOOTSTRAP + .size _start, 0 +_evba: + .org 0x00 + rjmp unknown_exception /* Unrecoverable exception */ + .org 0x04 + rjmp unknown_exception /* TLB multiple hit */ + .org 0x08 + rjmp unknown_exception /* Bus error data fetch */ + .org 0x0c + rjmp unknown_exception /* Bus error instruction fetch */ + .org 0x10 + rjmp unknown_exception /* NMI */ + .org 0x14 + rjmp unknown_exception /* Instruction address */ + .org 0x18 + rjmp unknown_exception /* ITLB protection */ + .org 0x1c + rjmp unknown_exception /* Breakpoint */ + .org 0x20 + rjmp unknown_exception /* Illegal opcode */ + .org 0x24 + rjmp unknown_exception /* Unimplemented instruction */ + .org 0x28 + rjmp unknown_exception /* Privilege violation */ + .org 0x2c + rjmp unknown_exception /* Floating-point */ + .org 0x30 + rjmp unknown_exception /* Coprocessor absent */ + .org 0x34 + rjmp unknown_exception /* Data Address (read) */ + .org 0x38 + rjmp unknown_exception /* Data Address (write) */ + .org 0x3c + rjmp unknown_exception /* DTLB Protection (read) */ + .org 0x40 + rjmp unknown_exception /* DTLB Protection (write) */ + .org 0x44 + rjmp unknown_exception /* DTLB Modified */ + + .org 0x50 + rjmp unknown_exception /* ITLB Miss */ + .org 0x60 + rjmp unknown_exception /* DTLB Miss (read) */ + .org 0x70 + rjmp unknown_exception /* DTLB Miss (write) */ + + .size _evba, . - _evba + + .align 2 + .type unknown_exception, @function +unknown_exception: + /* Figure out whether we're handling an exception (Exception + * mode) or just booting (Supervisor mode). */ + csrfcz SYSREG_M1_OFFSET + brcc at32ap_cpu_bootstrap + + /* This is an exception. Complain. */ + pushm r0-r12 + sub r8, sp, REG_R12 - REG_R0 - 4 + mov r9, lr + mfsr r10, SYSREG_RAR_EX + mfsr r11, SYSREG_RSR_EX + pushm r8-r11 + mfsr r12, SYSREG_ECR + mov r11, sp + rcall do_unknown_exception +1: rjmp 1b + + /* The COUNT/COMPARE timer interrupt handler */ + .global timer_interrupt_handler + .type timer_interrupt_handler,@function + .align 2 +timer_interrupt_handler: + /* + * Increment timer_overflow and re-write COMPARE with 0xffffffff. + * + * We're running at interrupt level 3, so we don't need to save + * r8-r12 or lr to the stack. + */ + lda.w r8, timer_overflow + ld.w r9, r8[0] + mov r10, -1 + mtsr SYSREG_COMPARE, r10 + sub r9, -1 + st.w r8[0], r9 + rete
+ /* + * CPU bootstrap after reset is handled here. SoC code may + * override this in case they need to initialize oscillators, + * etc. + */ + .section .text.at32ap_cpu_bootstrap, "ax", @progbits + .global at32ap_cpu_bootstrap + .weak at32ap_cpu_bootstrap + .type at32ap_cpu_bootstrap, @function + .align 2 +at32ap_cpu_bootstrap: /* Reset the Status Register */ mov r0, lo(SR_INIT) orh r0, hi(SR_INIT) @@ -66,9 +167,16 @@ _start: lddpc pc, 1f
.align 2 -1: .long 2f +1: .long at32ap_low_level_init + .size _start, . - _start
-2: lddpc sp, sp_init + /* Common CPU bootstrap code after oscillator/cache/etc. init */ + .section .text.avr32ap_low_level_init, "ax", @progbits + .global at32ap_low_level_init + .type at32ap_low_level_init, @function + .align 2 +at32ap_low_level_init: + lddpc sp, sp_init
/* Initialize the GOT pointer */ lddpc r6, got_init @@ -90,6 +198,7 @@ got_init: * Relocate the u-boot image into RAM and continue from there. * Does not return. */ + .section .text.relocate_code,"ax",@progbits .global relocate_code .type relocate_code,@function relocate_code: @@ -162,3 +271,5 @@ in_ram: .align 2 got_init_reloc: .long 3b - _GLOBAL_OFFSET_TABLE_ + + .size relocate_code, . - relocate_code