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| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
|---|---|
| 2 | /* |
| 3 | * xchg/cmpxchg operations for the Hexagon architecture |
| 4 | * |
| 5 | * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. |
| 6 | */ |
| 7 | |
| 8 | #ifndef _ASM_CMPXCHG_H |
| 9 | #define _ASM_CMPXCHG_H |
| 10 | |
| 11 | /* |
| 12 | * __arch_xchg - atomically exchange a register and a memory location |
| 13 | * @x: value to swap |
| 14 | * @ptr: pointer to memory |
| 15 | * @size: size of the value |
| 16 | * |
| 17 | * Only 4 bytes supported currently. |
| 18 | * |
| 19 | * Note: there was an errata for V2 about .new's and memw_locked. |
| 20 | * |
| 21 | */ |
| 22 | static inline unsigned long |
| 23 | __arch_xchg(unsigned long x, volatile void *ptr, int size) |
| 24 | { |
| 25 | unsigned long retval; |
| 26 | |
| 27 | /* Can't seem to use printk or panic here, so just stop */ |
| 28 | if (size != 4) do { asm volatile("brkpt;\n"); } while (1); |
| 29 | |
| 30 | __asm__ __volatile__ ( |
| 31 | "1: %0 = memw_locked(%1);\n"/* load into retval */ |
| 32 | " memw_locked(%1,P0) = %2;\n"/* store into memory */ |
| 33 | " if (!P0) jump 1b;\n" |
| 34 | : "=&r"(retval) |
| 35 | : "r"(ptr), "r"(x) |
| 36 | : "memory", "p0" |
| 37 | ); |
| 38 | return retval; |
| 39 | } |
| 40 | |
| 41 | /* |
| 42 | * Atomically swap the contents of a register with memory. Should be atomic |
| 43 | * between multiple CPU's and within interrupts on the same CPU. |
| 44 | */ |
| 45 | #define arch_xchg(ptr, v) ((__typeof__(*(ptr)))__arch_xchg((unsigned long)(v), (ptr), \ |
| 46 | sizeof(*(ptr)))) |
| 47 | |
| 48 | /* |
| 49 | * see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps. |
| 50 | * looks just like atomic_cmpxchg on our arch currently with a bunch of |
| 51 | * variable casting. |
| 52 | */ |
| 53 | |
| 54 | #define arch_cmpxchg(ptr, old, new) \ |
| 55 | ({ \ |
| 56 | __typeof__(ptr) __ptr = (ptr); \ |
| 57 | __typeof__(*(ptr)) __old = (old); \ |
| 58 | __typeof__(*(ptr)) __new = (new); \ |
| 59 | __typeof__(*(ptr)) __oldval = (__typeof__(*(ptr))) 0; \ |
| 60 | \ |
| 61 | asm volatile( \ |
| 62 | "1: %0 = memw_locked(%1);\n" \ |
| 63 | " { P0 = cmp.eq(%0,%2);\n" \ |
| 64 | " if (!P0.new) jump:nt 2f; }\n" \ |
| 65 | " memw_locked(%1,p0) = %3;\n" \ |
| 66 | " if (!P0) jump 1b;\n" \ |
| 67 | "2:\n" \ |
| 68 | : "=&r" (__oldval) \ |
| 69 | : "r" (__ptr), "r" (__old), "r" (__new) \ |
| 70 | : "memory", "p0" \ |
| 71 | ); \ |
| 72 | __oldval; \ |
| 73 | }) |
| 74 | |
| 75 | #endif /* _ASM_CMPXCHG_H */ |
| 76 |
Warning: That file was not part of the compilation database. It may have many parsing errors.