1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copied from arch/arm64/kernel/cpufeature.c
4 *
5 * Copyright (C) 2015 ARM Ltd.
6 * Copyright (C) 2017 SiFive
7 */
8
9 #include <linux/bitmap.h>
10 #include <linux/of.h>
11 #include <asm/processor.h>
12 #include <asm/hwcap.h>
13 #include <asm/smp.h>
14 #include <asm/switch_to.h>
15
16 unsigned long elf_hwcap __read_mostly;
17
18 /* Host ISA bitmap */
19 static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
20
21 #ifdef CONFIG_FPU
22 bool has_fpu __read_mostly;
23 #endif
24
25 /**
26 * riscv_isa_extension_base() - Get base extension word
27 *
28 * @isa_bitmap: ISA bitmap to use
29 * Return: base extension word as unsigned long value
30 *
31 * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
32 */
riscv_isa_extension_base(const unsigned long * isa_bitmap)33 unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
34 {
35 if (!isa_bitmap)
36 return riscv_isa[0];
37 return isa_bitmap[0];
38 }
39 EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
40
41 /**
42 * __riscv_isa_extension_available() - Check whether given extension
43 * is available or not
44 *
45 * @isa_bitmap: ISA bitmap to use
46 * @bit: bit position of the desired extension
47 * Return: true or false
48 *
49 * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
50 */
__riscv_isa_extension_available(const unsigned long * isa_bitmap,int bit)51 bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
52 {
53 const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
54
55 if (bit >= RISCV_ISA_EXT_MAX)
56 return false;
57
58 return test_bit(bit, bmap) ? true : false;
59 }
60 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
61
riscv_fill_hwcap(void)62 void riscv_fill_hwcap(void)
63 {
64 struct device_node *node;
65 const char *isa;
66 char print_str[BITS_PER_LONG + 1];
67 size_t i, j, isa_len;
68 static unsigned long isa2hwcap[256] = {0};
69
70 isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
71 isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
72 isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
73 isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
74 isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
75 isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
76
77 elf_hwcap = 0;
78
79 bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
80
81 for_each_of_cpu_node(node) {
82 unsigned long this_hwcap = 0;
83 unsigned long this_isa = 0;
84
85 if (riscv_of_processor_hartid(node) < 0)
86 continue;
87
88 if (of_property_read_string(node, "riscv,isa", &isa)) {
89 pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
90 continue;
91 }
92
93 i = 0;
94 isa_len = strlen(isa);
95 #if IS_ENABLED(CONFIG_32BIT)
96 if (!strncmp(isa, "rv32", 4))
97 i += 4;
98 #elif IS_ENABLED(CONFIG_64BIT)
99 if (!strncmp(isa, "rv64", 4))
100 i += 4;
101 #endif
102 for (; i < isa_len; ++i) {
103 this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
104 /*
105 * TODO: X, Y and Z extension parsing for Host ISA
106 * bitmap will be added in-future.
107 */
108 if ('a' <= isa[i] && isa[i] < 'x')
109 this_isa |= (1UL << (isa[i] - 'a'));
110 }
111
112 /*
113 * All "okay" hart should have same isa. Set HWCAP based on
114 * common capabilities of every "okay" hart, in case they don't
115 * have.
116 */
117 if (elf_hwcap)
118 elf_hwcap &= this_hwcap;
119 else
120 elf_hwcap = this_hwcap;
121
122 if (riscv_isa[0])
123 riscv_isa[0] &= this_isa;
124 else
125 riscv_isa[0] = this_isa;
126 }
127
128 /* We don't support systems with F but without D, so mask those out
129 * here. */
130 if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
131 pr_info("This kernel does not support systems with F but not D\n");
132 elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
133 }
134
135 memset(print_str, 0, sizeof(print_str));
136 for (i = 0, j = 0; i < BITS_PER_LONG; i++)
137 if (riscv_isa[0] & BIT_MASK(i))
138 print_str[j++] = (char)('a' + i);
139 pr_info("riscv: ISA extensions %s\n", print_str);
140
141 memset(print_str, 0, sizeof(print_str));
142 for (i = 0, j = 0; i < BITS_PER_LONG; i++)
143 if (elf_hwcap & BIT_MASK(i))
144 print_str[j++] = (char)('a' + i);
145 pr_info("riscv: ELF capabilities %s\n", print_str);
146
147 #ifdef CONFIG_FPU
148 if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
149 has_fpu = true;
150 #endif
151 }
152
