| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* |
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| 3 | * Copyright (C) 2020-2022 Loongson Technology Corporation Limited |
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| 4 | */ |
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| 5 | #include <linux/delay.h> |
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| 6 | #include <linux/export.h> |
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| 7 | #include <linux/smp.h> |
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| 8 | #include <linux/timex.h> |
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| 9 | |
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| 10 | #include <asm/processor.h> |
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| 11 | |
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| 12 | void __delay(unsigned long cycles) |
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| 13 | { |
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| 14 | u64 t0 = get_cycles(); |
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| 15 | |
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| 16 | while ((unsigned long)(get_cycles() - t0) < cycles) |
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| 17 | cpu_relax(); |
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| 18 | } |
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| 19 | EXPORT_SYMBOL(__delay); |
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| 20 | |
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| 21 | /* |
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| 22 | * Division by multiplication: you don't have to worry about |
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| 23 | * loss of precision. |
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| 24 | * |
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| 25 | * Use only for very small delays ( < 1 msec). Should probably use a |
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| 26 | * lookup table, really, as the multiplications take much too long with |
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| 27 | * short delays. This is a "reasonable" implementation, though (and the |
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| 28 | * first constant multiplications gets optimized away if the delay is |
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| 29 | * a constant) |
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| 30 | */ |
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| 31 | |
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| 32 | void __udelay(unsigned long us) |
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| 33 | { |
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| 34 | __delay((us * 0x000010c7ull * HZ * lpj_fine) >> 32); |
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| 35 | } |
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| 36 | EXPORT_SYMBOL(__udelay); |
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| 37 | |
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| 38 | void __ndelay(unsigned long ns) |
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| 39 | { |
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| 40 | __delay((ns * 0x00000005ull * HZ * lpj_fine) >> 32); |
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| 41 | } |
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| 42 | EXPORT_SYMBOL(__ndelay); |
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| 43 | |
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