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 #ifdef CONFIG_FPU 26 bool has_fpu __read_mostly; 27 #endif 28 29 void riscv_fill_hwcap(void) 30 { 31 struct device_node *node = NULL; 32 const char *isa; 33 size_t i; 34 static unsigned long isa2hwcap[256] = {0}; 35 36 isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I; 37 isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M; 38 isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A; 39 isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F; 40 isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D; 41 isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C; 42 43 elf_hwcap = 0; 44 45 /* 46 * We don't support running Linux on hertergenous ISA systems. For 47 * now, we just check the ISA of the first "okay" processor. 48 */ 49 while ((node = of_find_node_by_type(node, "cpu"))) 50 if (riscv_of_processor_hartid(node) >= 0) 51 break; 52 if (!node) { 53 pr_warning("Unable to find \"cpu\" devicetree entry"); 54 return; 55 } 56 57 if (of_property_read_string(node, "riscv,isa", &isa)) { 58 pr_warning("Unable to find \"riscv,isa\" devicetree entry"); 59 return; 60 } 61 62 for (i = 0; i < strlen(isa); ++i) 63 elf_hwcap |= isa2hwcap[(unsigned char)(isa[i])]; 64 65 /* We don't support systems with F but without D, so mask those out 66 * here. */ 67 if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) { 68 pr_info("This kernel does not support systems with F but not D"); 69 elf_hwcap &= ~COMPAT_HWCAP_ISA_F; 70 } 71 72 pr_info("elf_hwcap is 0x%lx", elf_hwcap); 73 74 #ifdef CONFIG_FPU 75 if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)) 76 has_fpu = true; 77 #endif 78 } 79