Merge tag 'riscv-for-linus-5.1-mw0' of git://git.kernel.org/pub/scm/linux/kernel...
[sfrench/cifs-2.6.git] / arch / riscv / kernel / cpufeature.c
1 /*
2  * Copied from arch/arm64/kernel/cpufeature.c
3  *
4  * Copyright (C) 2015 ARM Ltd.
5  * Copyright (C) 2017 SiFive
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19
20 #include <linux/of.h>
21 #include <asm/processor.h>
22 #include <asm/hwcap.h>
23 #include <asm/smp.h>
24
25 unsigned long elf_hwcap __read_mostly;
26 #ifdef CONFIG_FPU
27 bool has_fpu __read_mostly;
28 #endif
29
30 void riscv_fill_hwcap(void)
31 {
32         struct device_node *node;
33         const char *isa;
34         size_t i;
35         static unsigned long isa2hwcap[256] = {0};
36
37         isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
38         isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
39         isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
40         isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
41         isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
42         isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
43
44         elf_hwcap = 0;
45
46         for_each_of_cpu_node(node) {
47                 unsigned long this_hwcap = 0;
48
49                 if (riscv_of_processor_hartid(node) < 0)
50                         continue;
51
52                 if (of_property_read_string(node, "riscv,isa", &isa)) {
53                         pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
54                         continue;
55                 }
56
57                 for (i = 0; i < strlen(isa); ++i)
58                         this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
59
60                 /*
61                  * All "okay" hart should have same isa. Set HWCAP based on
62                  * common capabilities of every "okay" hart, in case they don't
63                  * have.
64                  */
65                 if (elf_hwcap)
66                         elf_hwcap &= this_hwcap;
67                 else
68                         elf_hwcap = this_hwcap;
69         }
70
71         /* We don't support systems with F but without D, so mask those out
72          * here. */
73         if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
74                 pr_info("This kernel does not support systems with F but not D\n");
75                 elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
76         }
77
78         pr_info("elf_hwcap is 0x%lx\n", elf_hwcap);
79
80 #ifdef CONFIG_FPU
81         if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
82                 has_fpu = true;
83 #endif
84 }