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41 lines
981 B
41 lines
981 B
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* Copyright (c) 2014-2015 The Linux Foundation. All rights reserved. |
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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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