From 9746b7bf27d4a3c7c0de78b26ec9f217887f4e7d Mon Sep 17 00:00:00 2001 From: Paul Kocialkowski Date: Tue, 22 Sep 2015 22:16:33 +0200 Subject: [PATCH 1/2] armv7: Word-sized/half-word-sized memory operations for 32/16 bit read/write Some registers only allow word-sized or half-word-sized operations and will cause a data fault when accessed with byte-sized operations. However, the compiler may or may not break such an operation into smaller (byte-sized) chunks. Thus, we need to reliably perform word-sized operations for 32 bit read/write and half-word-sized operations for 16 bit read/write. This is particularly the case on the rk3288 SRAM registers, where the watchdog tombstone is stored. Moving to GCC 5.2.0 introduced a change of strategy in the compiler, where a 32 bit read would be broken into byte-sized chunks, which caused a data fault when accessing the watchdog tombstone register. The definitions for byte-sized memory operations are also adapted to stay consistent with the rest. Change-Id: I1fb3fc139e0a813acf9d70f14386a9603c9f9ede Signed-off-by: Paul Kocialkowski --- src/arch/arm/include/armv7/arch/io.h | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/src/arch/arm/include/armv7/arch/io.h b/src/arch/arm/include/armv7/arch/io.h index 9d06003..94cb131 100644 --- a/src/arch/arm/include/armv7/arch/io.h +++ b/src/arch/arm/include/armv7/arch/io.h @@ -29,40 +29,49 @@ static inline uint8_t read8(const void *addr) { + uint8_t val; + dmb(); - return *(volatile uint8_t *)addr; + asm volatile ("ldrb %0, [%1]" : "=r" (val) : "r" (addr) : "memory"); + return val; } static inline uint16_t read16(const void *addr) { + uint16_t val; + dmb(); - return *(volatile uint16_t *)addr; + asm volatile ("ldrh %0, [%1]" : "=r" (val) : "r" (addr) : "memory"); + return val; } static inline uint32_t read32(const void *addr) { + uint32_t val; + dmb(); - return *(volatile uint32_t *)addr; + asm volatile ("ldr %0, [%1]" : "=r" (val) : "r" (addr) : "memory"); + return val; } static inline void write8(void *addr, uint8_t val) { dmb(); - *(volatile uint8_t *)addr = val; + asm volatile ("strb %0, [%1]" : : "r" (val), "r" (addr) : "memory"); dmb(); } static inline void write16(void *addr, uint16_t val) { dmb(); - *(volatile uint16_t *)addr = val; + asm volatile ("strh %0, [%1]" : : "r" (val), "r" (addr) : "memory"); dmb(); } static inline void write32(void *addr, uint32_t val) { dmb(); - *(volatile uint32_t *)addr = val; + asm volatile ("str %0, [%1]" : : "r" (val), "r" (addr) : "memory"); dmb(); } -- 1.9.1