162306a36Sopenharmony_ci/* SPDX-License-Identifier: GPL-2.0-only */ 262306a36Sopenharmony_ci/* Copyright (c) 2014-2015 The Linux Foundation. All rights reserved. 362306a36Sopenharmony_ci * 462306a36Sopenharmony_ci * A call to __dcc_getchar() or __dcc_putchar() is typically followed by 562306a36Sopenharmony_ci * a call to __dcc_getstatus(). We want to make sure that the CPU does 662306a36Sopenharmony_ci * not speculative read the DCC status before executing the read or write 762306a36Sopenharmony_ci * instruction. That's what the ISBs are for. 862306a36Sopenharmony_ci * 962306a36Sopenharmony_ci * The 'volatile' ensures that the compiler does not cache the status bits, 1062306a36Sopenharmony_ci * and instead reads the DCC register every time. 1162306a36Sopenharmony_ci */ 1262306a36Sopenharmony_ci#ifndef __ASM_DCC_H 1362306a36Sopenharmony_ci#define __ASM_DCC_H 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ci#include <asm/barrier.h> 1662306a36Sopenharmony_ci#include <asm/sysreg.h> 1762306a36Sopenharmony_ci 1862306a36Sopenharmony_cistatic inline u32 __dcc_getstatus(void) 1962306a36Sopenharmony_ci{ 2062306a36Sopenharmony_ci return read_sysreg(mdccsr_el0); 2162306a36Sopenharmony_ci} 2262306a36Sopenharmony_ci 2362306a36Sopenharmony_cistatic inline char __dcc_getchar(void) 2462306a36Sopenharmony_ci{ 2562306a36Sopenharmony_ci char c = read_sysreg(dbgdtrrx_el0); 2662306a36Sopenharmony_ci isb(); 2762306a36Sopenharmony_ci 2862306a36Sopenharmony_ci return c; 2962306a36Sopenharmony_ci} 3062306a36Sopenharmony_ci 3162306a36Sopenharmony_cistatic inline void __dcc_putchar(char c) 3262306a36Sopenharmony_ci{ 3362306a36Sopenharmony_ci /* 3462306a36Sopenharmony_ci * The typecast is to make absolutely certain that 'c' is 3562306a36Sopenharmony_ci * zero-extended. 3662306a36Sopenharmony_ci */ 3762306a36Sopenharmony_ci write_sysreg((unsigned char)c, dbgdtrtx_el0); 3862306a36Sopenharmony_ci isb(); 3962306a36Sopenharmony_ci} 4062306a36Sopenharmony_ci 4162306a36Sopenharmony_ci#endif 42