arch/mips/kernel/cpu-r3k-probe.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Processor capabilities determination functions.
   4  *
   5  * Copyright (C) xxxx  the Anonymous
   6  * Copyright (C) 1994 - 2006 Ralf Baechle
   7  * Copyright (C) 2003, 2004  Maciej W. Rozycki
   8  * Copyright (C) 2001, 2004, 2011, 2012  MIPS Technologies, Inc.
   9  */
  10 #include <linux/init.h>
  11 #include <linux/kernel.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/smp.h>
  14 #include <linux/stddef.h>
  15 #include <linux/export.h>
  16
  17 #include <asm/bugs.h>
  18 #include <asm/cpu.h>
  19 #include <asm/cpu-features.h>
  20 #include <asm/cpu-type.h>
  21 #include <asm/fpu.h>
  22 #include <asm/mipsregs.h>
  23 #include <asm/elf.h>
  24 #include <asm/traps.h>
  25
  26 #include "fpu-probe.h"
  27
  28 /* Hardware capabilities */
  29 unsigned int elf_hwcap __read_mostly;
  30 EXPORT_SYMBOL_GPL(elf_hwcap);
  31
  32 void __init check_bugs32(void)
  33 {
  34
  35 }
  36
  37 /*
  38  * Probe whether cpu has config register by trying to play with
  39  * alternate cache bit and see whether it matters.
  40  * It's used by cpu_probe to distinguish between R3000A and R3081.
  41  */
  42 static inline int cpu_has_confreg(void)
  43 {
  44 #ifdef CONFIG_CPU_R3000
  45         unsigned long size1, size2;
  46         unsigned long cfg = read_c0_conf();
  47
  48         size1 = r3k_cache_size(ST0_ISC);
  49         write_c0_conf(cfg ^ R30XX_CONF_AC);
  50         size2 = r3k_cache_size(ST0_ISC);
  51         write_c0_conf(cfg);
  52         return size1 != size2;
  53 #else
  54         return 0;
  55 #endif
  56 }
  57
  58 static inline void set_elf_platform(int cpu, const char *plat)
  59 {
  60         if (cpu == 0)
  61                 __elf_platform = plat;
  62 }
  63
  64 const char *__cpu_name[NR_CPUS];
  65 const char *__elf_platform;
  66 const char *__elf_base_platform;
  67
  68 void cpu_probe(void)
  69 {
  70         struct cpuinfo_mips *c = &current_cpu_data;
  71         unsigned int cpu = smp_processor_id();
  72
  73         /*
  74          * Set a default elf platform, cpu probe may later
  75          * overwrite it with a more precise value
  76          */
  77         set_elf_platform(cpu, "mips");
  78
  79         c->processor_id = PRID_IMP_UNKNOWN;
  80         c->fpu_id       = FPIR_IMP_NONE;
  81         c->cputype      = CPU_UNKNOWN;
  82         c->writecombine = _CACHE_UNCACHED;
  83
  84         c->fpu_csr31    = FPU_CSR_RN;
  85         c->fpu_msk31    = FPU_CSR_RSVD | FPU_CSR_ABS2008 | FPU_CSR_NAN2008 |
  86                           FPU_CSR_CONDX | FPU_CSR_FS;
  87
  88         c->srsets = 1;
  89
  90         c->processor_id = read_c0_prid();
  91         switch (c->processor_id & (PRID_COMP_MASK | PRID_IMP_MASK)) {
  92         case PRID_COMP_LEGACY | PRID_IMP_R2000:
  93                 c->cputype = CPU_R2000;
  94                 __cpu_name[cpu] = "R2000";
  95                 c->options = MIPS_CPU_TLB | MIPS_CPU_3K_CACHE |
  96                              MIPS_CPU_NOFPUEX;
  97                 if (__cpu_has_fpu())
  98                         c->options |= MIPS_CPU_FPU;
  99                 c->tlbsize = 64;
 100                 break;
 101         case PRID_COMP_LEGACY | PRID_IMP_R3000:
 102                 if ((c->processor_id & PRID_REV_MASK) == PRID_REV_R3000A) {
 103                         if (cpu_has_confreg()) {
 104                                 c->cputype = CPU_R3081E;
 105                                 __cpu_name[cpu] = "R3081";
 106                         } else {
 107                                 c->cputype = CPU_R3000A;
 108                                 __cpu_name[cpu] = "R3000A";
 109                         }
 110                 } else {
 111                         c->cputype = CPU_R3000;
 112                         __cpu_name[cpu] = "R3000";
 113                 }
 114                 c->options = MIPS_CPU_TLB | MIPS_CPU_3K_CACHE |
 115                              MIPS_CPU_NOFPUEX;
 116                 if (__cpu_has_fpu())
 117                         c->options |= MIPS_CPU_FPU;
 118                 c->tlbsize = 64;
 119                 break;
 120         }
 121
 122         BUG_ON(!__cpu_name[cpu]);
 123         BUG_ON(c->cputype == CPU_UNKNOWN);
 124
 125         /*
 126          * Platform code can force the cpu type to optimize code
 127          * generation. In that case be sure the cpu type is correctly
 128          * manually setup otherwise it could trigger some nasty bugs.
 129          */
 130         BUG_ON(current_cpu_type() != c->cputype);
 131
 132         if (mips_fpu_disabled)
 133                 c->options &= ~MIPS_CPU_FPU;
 134
 135         if (c->options & MIPS_CPU_FPU)
 136                 cpu_set_fpu_opts(c);
 137         else
 138                 cpu_set_nofpu_opts(c);
 139
 140         reserve_exception_space(0, 0x400);
 141 }
 142
 143 void cpu_report(void)
 144 {
 145         struct cpuinfo_mips *c = &current_cpu_data;
 146
 147         pr_info("CPU%d revision is: %08x (%s)\n",
 148                 smp_processor_id(), c->processor_id, cpu_name_string());
 149         if (c->options & MIPS_CPU_FPU)
 150                 pr_info("FPU revision is: %08x\n", c->fpu_id);
 151 }