/* 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