1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
4 */
5
6 #ifndef __LINUX_CPUFEATURE_H
7 #define __LINUX_CPUFEATURE_H
8
9 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
10
11 #include <linux/init.h>
12 #include <linux/mod_devicetable.h>
13 #include <asm/cpufeature.h>
14
15 /*
16 * Macros imported from <asm/cpufeature.h>:
17 * - cpu_feature(x) ordinal value of feature called 'x'
18 * - cpu_have_feature(u32 n) whether feature #n is available
19 * - MAX_CPU_FEATURES upper bound for feature ordinal values
20 * Optional:
21 * - CPU_FEATURE_TYPEFMT format string fragment for printing the cpu type
22 * - CPU_FEATURE_TYPEVAL set of values matching the format string above
23 */
24
25 #ifndef CPU_FEATURE_TYPEFMT
26 #define CPU_FEATURE_TYPEFMT "%s"
27 #endif
28
29 #ifndef CPU_FEATURE_TYPEVAL
30 #define CPU_FEATURE_TYPEVAL ELF_PLATFORM
31 #endif
32
33 /*
34 * Use module_cpu_feature_match(feature, module_init_function) to
35 * declare that
36 * a) the module shall be probed upon discovery of CPU feature 'feature'
37 * (typically at boot time using udev)
38 * b) the module must not be loaded if CPU feature 'feature' is not present
39 * (not even by manual insmod).
40 *
41 * For a list of legal values for 'feature', please consult the file
42 * 'asm/cpufeature.h' of your favorite architecture.
43 */
44 #define module_cpu_feature_match(x, __initfunc) \
45 static struct cpu_feature const __maybe_unused cpu_feature_match_ ## x[] = \
46 { { .feature = cpu_feature(x) }, { } }; \
47 MODULE_DEVICE_TABLE(cpu, cpu_feature_match_ ## x); \
48 \
49 static int __init cpu_feature_match_ ## x ## _init(void) \
50 { \
51 if (!cpu_have_feature(cpu_feature(x))) \
52 return -ENODEV; \
53 return __initfunc(); \
54 } \
55 module_init(cpu_feature_match_ ## x ## _init)
56
57 #endif
58 #endif