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d0a69d9f38
A while back we added {read,write}_sysreg accessors to handle accesses
to system registers, without the usual boilerplate asm volatile,
temporary variable, etc.
This patch makes use of these in the arm64 DCC accessors to make the
code shorter and clearer.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/* Copyright (c) 2014-2015 The Linux Foundation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* A call to __dcc_getchar() or __dcc_putchar() is typically followed by
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* a call to __dcc_getstatus(). We want to make sure that the CPU does
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* not speculative read the DCC status before executing the read or write
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* instruction. That's what the ISBs are for.
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*
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* The 'volatile' ensures that the compiler does not cache the status bits,
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* and instead reads the DCC register every time.
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*/
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#ifndef __ASM_DCC_H
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#define __ASM_DCC_H
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#include <asm/barrier.h>
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#include <asm/sysreg.h>
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static inline u32 __dcc_getstatus(void)
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{
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return read_sysreg(mdccsr_el0);
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}
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static inline char __dcc_getchar(void)
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{
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char c = read_sysreg(dbgdtrrx_el0);
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isb();
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return c;
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}
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static inline void __dcc_putchar(char c)
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{
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/*
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* The typecast is to make absolutely certain that 'c' is
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* zero-extended.
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*/
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write_sysreg((unsigned char)c, dbgdtrtx_el0);
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isb();
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}
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#endif
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