49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
/* Copyright (c) 2014-2015 The Linux Foundation. All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 and
|
|
* only version 2 as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* 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
|