memtest86plus/system/memrw32.h

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// SPDX-License-Identifier: GPL-2.0
#ifndef MEMRW32_H
#define MEMRW32_H
/**
* \file
*
* Provides some 32-bit memory access functions. These stop the compiler
* optimizing accesses which need to be ordered and atomic. Mostly used
* for accessing memory-mapped hardware registers.
*
*//*
* Copyright (C) 2021-2022 Martin Whitaker.
*/
#include <stdint.h>
/**
* Reads and returns the value stored in the 32-bit memory location pointed
* to by ptr.
*/
static inline uint32_t read32(const volatile uint32_t *ptr)
{
uint32_t val;
__asm__ __volatile__(
"movl %1, %0"
: "=r" (val)
: "m" (*ptr)
: "memory"
);
return val;
}
/**
* Writes val to the 32-bit memory location pointed to by ptr.
*/
static inline void write32(const volatile uint32_t *ptr, uint32_t val)
{
__asm__ __volatile__(
"movl %1, %0"
:
: "m" (*ptr),
"r" (val)
: "memory"
);
}
/**
* Writes val to the 32-bit memory location pointed to by ptr. Reads it
* back (and discards it) to ensure the write is complete.
*/
static inline void flush32(const volatile uint32_t *ptr, uint32_t val)
{
__asm__ __volatile__(
"movl %1, %0\n"
"movl %0, %1"
:
: "m" (*ptr),
"r" (val)
: "memory"
);
}
#endif // MEMRW32_H