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| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
|---|---|
| 2 | /* Copyright (c) 2014-2015 The Linux Foundation. All rights reserved. |
| 3 | * |
| 4 | * A call to __dcc_getchar() or __dcc_putchar() is typically followed by |
| 5 | * a call to __dcc_getstatus(). We want to make sure that the CPU does |
| 6 | * not speculative read the DCC status before executing the read or write |
| 7 | * instruction. That's what the ISBs are for. |
| 8 | * |
| 9 | * The 'volatile' ensures that the compiler does not cache the status bits, |
| 10 | * and instead reads the DCC register every time. |
| 11 | */ |
| 12 | #ifndef __ASM_DCC_H |
| 13 | #define __ASM_DCC_H |
| 14 | |
| 15 | #include <asm/barrier.h> |
| 16 | #include <asm/sysreg.h> |
| 17 | |
| 18 | static inline u32 __dcc_getstatus(void) |
| 19 | { |
| 20 | return read_sysreg(mdccsr_el0); |
| 21 | } |
| 22 | |
| 23 | static inline char __dcc_getchar(void) |
| 24 | { |
| 25 | char c = read_sysreg(dbgdtrrx_el0); |
| 26 | isb(); |
| 27 | |
| 28 | return c; |
| 29 | } |
| 30 | |
| 31 | static inline void __dcc_putchar(char c) |
| 32 | { |
| 33 | /* |
| 34 | * The typecast is to make absolutely certain that 'c' is |
| 35 | * zero-extended. |
| 36 | */ |
| 37 | write_sysreg((unsigned char)c, dbgdtrtx_el0); |
| 38 | isb(); |
| 39 | } |
| 40 | |
| 41 | #endif |
| 42 |
Warning: This file is not a C or C++ file. It does not have highlighting.