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
24unsigned long elf_hwcap __read_mostly;
25
26void riscv_fill_hwcap(void)
27{
28	struct device_node *node;
29	const char *isa;
30	size_t i;
31	static unsigned long isa2hwcap[256] = {0};
32
33	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
34	isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
35	isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
36	isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
37	isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
38	isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
39
40	elf_hwcap = 0;
41
42	/*
43	 * We don't support running Linux on hertergenous ISA systems.  For
44	 * now, we just check the ISA of the first processor.
45	 */
46	node = of_find_node_by_type(NULL, "cpu");
47	if (!node) {
48		pr_warning("Unable to find \"cpu\" devicetree entry");
49		return;
50	}
51
52	if (of_property_read_string(node, "riscv,isa", &isa)) {
53		pr_warning("Unable to find \"riscv,isa\" devicetree entry");
54		return;
55	}
56
57	for (i = 0; i < strlen(isa); ++i)
58		elf_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
59
60	pr_info("elf_hwcap is 0x%lx", elf_hwcap);
61}