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75 lines
1.9 KiB
75 lines
1.9 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* xchg/cmpxchg operations for the Hexagon architecture |
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* |
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* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. |
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*/ |
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#ifndef _ASM_CMPXCHG_H |
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#define _ASM_CMPXCHG_H |
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/* |
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* __xchg - atomically exchange a register and a memory location |
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* @x: value to swap |
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* @ptr: pointer to memory |
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* @size: size of the value |
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* |
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* Only 4 bytes supported currently. |
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* |
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* Note: there was an errata for V2 about .new's and memw_locked. |
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* |
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*/ |
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static inline unsigned long __xchg(unsigned long x, volatile void *ptr, |
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int size) |
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{ |
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unsigned long retval; |
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/* Can't seem to use printk or panic here, so just stop */ |
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if (size != 4) do { asm volatile("brkpt;\n"); } while (1); |
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__asm__ __volatile__ ( |
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"1: %0 = memw_locked(%1);\n" /* load into retval */ |
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" memw_locked(%1,P0) = %2;\n" /* store into memory */ |
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" if (!P0) jump 1b;\n" |
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: "=&r" (retval) |
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: "r" (ptr), "r" (x) |
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: "memory", "p0" |
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); |
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return retval; |
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} |
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/* |
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* Atomically swap the contents of a register with memory. Should be atomic |
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* between multiple CPU's and within interrupts on the same CPU. |
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*/ |
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#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), \ |
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sizeof(*(ptr)))) |
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/* |
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* see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps. |
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* looks just like atomic_cmpxchg on our arch currently with a bunch of |
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* variable casting. |
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*/ |
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#define cmpxchg(ptr, old, new) \ |
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({ \ |
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__typeof__(ptr) __ptr = (ptr); \ |
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__typeof__(*(ptr)) __old = (old); \ |
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__typeof__(*(ptr)) __new = (new); \ |
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__typeof__(*(ptr)) __oldval = 0; \ |
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\ |
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asm volatile( \ |
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"1: %0 = memw_locked(%1);\n" \ |
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" { P0 = cmp.eq(%0,%2);\n" \ |
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" if (!P0.new) jump:nt 2f; }\n" \ |
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" memw_locked(%1,p0) = %3;\n" \ |
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" if (!P0) jump 1b;\n" \ |
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"2:\n" \ |
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: "=&r" (__oldval) \ |
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: "r" (__ptr), "r" (__old), "r" (__new) \ |
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: "memory", "p0" \ |
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); \ |
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__oldval; \ |
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}) |
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#endif /* _ASM_CMPXCHG_H */
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