From 90c68c6dbcb439b4d8ed9736463d80b98c95771f Mon Sep 17 00:00:00 2001 From: Thomas Bogendoerfer Date: Thu, 8 Oct 2020 23:33:26 +0200 Subject: [PATCH] MIPS: cpu-probe: introduce exclusive R3k CPU probe Running a kernel on a R3k of machine definitly will never see one of the newer CPU cores. And since R3k system usually are low on memory we could save quite some kbytes: text data bss dec hex filename 15070 88 32 15190 3b56 arch/mips/kernel/cpu-probe.o 844 4 16 864 360 arch/mips/kernel/cpu-r3k-probe.o Signed-off-by: Thomas Bogendoerfer --- arch/mips/kernel/Makefile | 8 +- arch/mips/kernel/cpu-r3k-probe.c | 171 +++++++++++++++++++++++++++++++ 2 files changed, 178 insertions(+), 1 deletion(-) create mode 100644 arch/mips/kernel/cpu-r3k-probe.c diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile index 026801c21724..2a05b923f579 100644 --- a/arch/mips/kernel/Makefile +++ b/arch/mips/kernel/Makefile @@ -5,11 +5,17 @@ extra-y := head.o vmlinux.lds -obj-y += cmpxchg.o cpu-probe.o branch.o elf.o entry.o genex.o idle.o irq.o \ +obj-y += branch.o cmpxchg.o elf.o entry.o genex.o idle.o irq.o \ process.o prom.o ptrace.o reset.o setup.o signal.o \ syscall.o time.o topology.o traps.o unaligned.o watch.o \ vdso.o cacheinfo.o +ifdef CONFIG_CPU_R3K_TLB +obj-y += cpu-r3k-probe.o +else +obj-y += cpu-probe.o +endif + ifdef CONFIG_FUNCTION_TRACER CFLAGS_REMOVE_ftrace.o = -pg CFLAGS_REMOVE_early_printk.o = -pg diff --git a/arch/mips/kernel/cpu-r3k-probe.c b/arch/mips/kernel/cpu-r3k-probe.c new file mode 100644 index 000000000000..abdbbe8c5a43 --- /dev/null +++ b/arch/mips/kernel/cpu-r3k-probe.c @@ -0,0 +1,171 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Processor capabilities determination functions. + * + * Copyright (C) xxxx the Anonymous + * Copyright (C) 1994 - 2006 Ralf Baechle + * Copyright (C) 2003, 2004 Maciej W. Rozycki + * Copyright (C) 2001, 2004, 2011, 2012 MIPS Technologies, Inc. + */ +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +#include "fpu-probe.h" + +/* Hardware capabilities */ +unsigned int elf_hwcap __read_mostly; +EXPORT_SYMBOL_GPL(elf_hwcap); + +void __init check_bugs32(void) +{ + +} + +/* + * Probe whether cpu has config register by trying to play with + * alternate cache bit and see whether it matters. + * It's used by cpu_probe to distinguish between R3000A and R3081. + */ +static inline int cpu_has_confreg(void) +{ +#ifdef CONFIG_CPU_R3000 + extern unsigned long r3k_cache_size(unsigned long); + unsigned long size1, size2; + unsigned long cfg = read_c0_conf(); + + size1 = r3k_cache_size(ST0_ISC); + write_c0_conf(cfg ^ R30XX_CONF_AC); + size2 = r3k_cache_size(ST0_ISC); + write_c0_conf(cfg); + return size1 != size2; +#else + return 0; +#endif +} + +static inline void set_elf_platform(int cpu, const char *plat) +{ + if (cpu == 0) + __elf_platform = plat; +} + +const char *__cpu_name[NR_CPUS]; +const char *__elf_platform; +const char *__elf_base_platform; + +void cpu_probe(void) +{ + struct cpuinfo_mips *c = ¤t_cpu_data; + unsigned int cpu = smp_processor_id(); + + /* + * Set a default elf platform, cpu probe may later + * overwrite it with a more precise value + */ + set_elf_platform(cpu, "mips"); + + c->processor_id = PRID_IMP_UNKNOWN; + c->fpu_id = FPIR_IMP_NONE; + c->cputype = CPU_UNKNOWN; + c->writecombine = _CACHE_UNCACHED; + + c->fpu_csr31 = FPU_CSR_RN; + c->fpu_msk31 = FPU_CSR_RSVD | FPU_CSR_ABS2008 | FPU_CSR_NAN2008 | + FPU_CSR_CONDX | FPU_CSR_FS; + + c->srsets = 1; + + c->processor_id = read_c0_prid(); + switch (c->processor_id & (PRID_COMP_MASK | PRID_IMP_MASK)) { + case PRID_COMP_LEGACY | PRID_IMP_R2000: + c->cputype = CPU_R2000; + __cpu_name[cpu] = "R2000"; + c->options = MIPS_CPU_TLB | MIPS_CPU_3K_CACHE | + MIPS_CPU_NOFPUEX; + if (__cpu_has_fpu()) + c->options |= MIPS_CPU_FPU; + c->tlbsize = 64; + break; + case PRID_COMP_LEGACY | PRID_IMP_R3000: + if ((c->processor_id & PRID_REV_MASK) == PRID_REV_R3000A) { + if (cpu_has_confreg()) { + c->cputype = CPU_R3081E; + __cpu_name[cpu] = "R3081"; + } else { + c->cputype = CPU_R3000A; + __cpu_name[cpu] = "R3000A"; + } + } else { + c->cputype = CPU_R3000; + __cpu_name[cpu] = "R3000"; + } + c->options = MIPS_CPU_TLB | MIPS_CPU_3K_CACHE | + MIPS_CPU_NOFPUEX; + if (__cpu_has_fpu()) + c->options |= MIPS_CPU_FPU; + c->tlbsize = 64; + break; + case PRID_COMP_LEGACY | PRID_IMP_TX39: + c->options = MIPS_CPU_TLB | MIPS_CPU_TX39_CACHE; + + if ((c->processor_id & 0xf0) == (PRID_REV_TX3927 & 0xf0)) { + c->cputype = CPU_TX3927; + __cpu_name[cpu] = "TX3927"; + c->tlbsize = 64; + } else { + switch (c->processor_id & PRID_REV_MASK) { + case PRID_REV_TX3912: + c->cputype = CPU_TX3912; + __cpu_name[cpu] = "TX3912"; + c->tlbsize = 32; + break; + case PRID_REV_TX3922: + c->cputype = CPU_TX3922; + __cpu_name[cpu] = "TX3922"; + c->tlbsize = 64; + break; + } + } + break; + } + + BUG_ON(!__cpu_name[cpu]); + BUG_ON(c->cputype == CPU_UNKNOWN); + + /* + * Platform code can force the cpu type to optimize code + * generation. In that case be sure the cpu type is correctly + * manually setup otherwise it could trigger some nasty bugs. + */ + BUG_ON(current_cpu_type() != c->cputype); + + if (mips_fpu_disabled) + c->options &= ~MIPS_CPU_FPU; + + if (c->options & MIPS_CPU_FPU) + cpu_set_fpu_opts(c); + else + cpu_set_nofpu_opts(c); +} + +void cpu_report(void) +{ + struct cpuinfo_mips *c = ¤t_cpu_data; + + pr_info("CPU%d revision is: %08x (%s)\n", + smp_processor_id(), c->processor_id, cpu_name_string()); + if (c->options & MIPS_CPU_FPU) + pr_info("FPU revision is: %08x\n", c->fpu_id); +} -- 2.20.1