xref: /openbmc/linux/include/linux/cpufeature.h (revision d2912cb1)
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
59