1 /*
2  * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8 
9 #ifndef __ASM_CPUFEATURE_H
10 #define __ASM_CPUFEATURE_H
11 
12 #include <asm/hwcap.h>
13 
14 /*
15  * In the arm64 world (as in the ARM world), elf_hwcap is used both internally
16  * in the kernel and for user space to keep track of which optional features
17  * are supported by the current system. So let's map feature 'x' to HWCAP_x.
18  * Note that HWCAP_x constants are bit fields so we need to take the log.
19  */
20 
21 #define MAX_CPU_FEATURES	(8 * sizeof(elf_hwcap))
22 #define cpu_feature(x)		ilog2(HWCAP_ ## x)
23 
24 #define ARM64_WORKAROUND_CLEAN_CACHE		0
25 #define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE	1
26 #define ARM64_WORKAROUND_845719			2
27 #define ARM64_HAS_SYSREG_GIC_CPUIF		3
28 #define ARM64_HAS_PAN				4
29 #define ARM64_HAS_LSE_ATOMICS			5
30 
31 #define ARM64_NCAPS				6
32 
33 #ifndef __ASSEMBLY__
34 
35 #include <linux/kernel.h>
36 
37 struct arm64_cpu_capabilities {
38 	const char *desc;
39 	u16 capability;
40 	bool (*matches)(const struct arm64_cpu_capabilities *);
41 	void (*enable)(void);
42 	union {
43 		struct {	/* To be used for erratum handling only */
44 			u32 midr_model;
45 			u32 midr_range_min, midr_range_max;
46 		};
47 
48 		struct {	/* Feature register checking */
49 			int field_pos;
50 			int min_field_value;
51 		};
52 	};
53 };
54 
55 extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
56 
57 static inline bool cpu_have_feature(unsigned int num)
58 {
59 	return elf_hwcap & (1UL << num);
60 }
61 
62 static inline bool cpus_have_cap(unsigned int num)
63 {
64 	if (num >= ARM64_NCAPS)
65 		return false;
66 	return test_bit(num, cpu_hwcaps);
67 }
68 
69 static inline void cpus_set_cap(unsigned int num)
70 {
71 	if (num >= ARM64_NCAPS)
72 		pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n",
73 			num, ARM64_NCAPS);
74 	else
75 		__set_bit(num, cpu_hwcaps);
76 }
77 
78 static inline int __attribute_const__ cpuid_feature_extract_field(u64 features,
79 								  int field)
80 {
81 	return (s64)(features << (64 - 4 - field)) >> (64 - 4);
82 }
83 
84 
85 void check_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
86 			    const char *info);
87 void check_local_cpu_errata(void);
88 void check_local_cpu_features(void);
89 bool cpu_supports_mixed_endian_el0(void);
90 bool system_supports_mixed_endian_el0(void);
91 
92 #endif /* __ASSEMBLY__ */
93 
94 #endif
95