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
  24 unsigned long elf_hwcap __read_mostly;
  25
  26 void 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 }