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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 = 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.