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/* SPDX-License-Identifier: GPL-2.0-only */
/* Copyright (c) 2014-2015 The Linux Foundation. All rights reserved.
*
* A call to __dcc_getchar() or __dcc_putchar() is typically followed by
* a call to __dcc_getstatus(). We want to make sure that the CPU does
* not speculative read the DCC status before executing the read or write
* instruction. That's what the ISBs are for.
*
* The 'volatile' ensures that the compiler does not cache the status bits,
* and instead reads the DCC register every time.
*/
#ifndef __ASM_DCC_H
#define __ASM_DCC_H
#include <asm/barrier.h>
#include <asm/sysreg.h>
static inline u32 __dcc_getstatus(void)
{
return read_sysreg(mdccsr_el0);
}
static inline char __dcc_getchar(void)
{
char c = read_sysreg(dbgdtrrx_el0);
isb();
return c;
}
static inline void __dcc_putchar(char c)
{
/*
* The typecast is to make absolutely certain that 'c' is
* zero-extended.
*/
write_sysreg((unsigned char)c, dbgdtrtx_el0);
isb();
}
#endif
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