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 */
29unsigned int elf_hwcap __read_mostly;
30EXPORT_SYMBOL_GPL(elf_hwcap);
31
32void __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 */
42static 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
58static inline void set_elf_platform(int cpu, const char *plat)
59{
60 if (cpu == 0)
61 __elf_platform = plat;
62}
63
64const char *__cpu_name[NR_CPUS];
65const char *__elf_platform;
66const char *__elf_base_platform;
67
68void 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, plat: "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
143void 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}
152

source code of linux/arch/mips/kernel/cpu-r3k-probe.c