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