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Re: [PATCH V16 02/12] MIPS: Loongson: Add basic Loongson-3 CPU support

To: Huacai Chen <chenhc@lemote.com>
Subject: Re: [PATCH V16 02/12] MIPS: Loongson: Add basic Loongson-3 CPU support
From: Aurelien Jarno <aurelien@aurel32.net>
Date: Thu, 9 Jan 2014 22:36:24 +0100
Cc: Ralf Baechle <ralf@linux-mips.org>, John Crispin <john@phrozen.org>, "Steven J. Hill" <Steven.Hill@imgtec.com>, linux-mips@linux-mips.org, Fuxin Zhang <zhangfx@lemote.com>, Zhangjin Wu <wuzhangjin@gmail.com>, Hongliang Tao <taohl@lemote.com>, Hua Yan <yanh@lemote.com>
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References: <1389149068-24376-1-git-send-email-chenhc@lemote.com> <1389149068-24376-3-git-send-email-chenhc@lemote.com> <20140108195838.GA10463@hall.aurel32.net> <CAAhV-H4tx=sCk=iUwuCfnCS+rbmtu5Y_UcpAn6JXDoobA+OGrQ@mail.gmail.com>
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On Thu, Jan 09, 2014 at 04:30:54PM +0800, Huacai Chen wrote:
> On Thu, Jan 9, 2014 at 3:58 AM, Aurelien Jarno <aurelien@aurel32.net> wrote:
> 
> > On Wed, Jan 08, 2014 at 10:44:18AM +0800, Huacai Chen wrote:
> > > Basic Loongson-3 CPU support include CPU probing and TLB/cache
> > > initializing.
> > >
> > > Signed-off-by: Huacai Chen <chenhc@lemote.com>
> > > Signed-off-by: Hongliang Tao <taohl@lemote.com>
> > > Signed-off-by: Hua Yan <yanh@lemote.com>
> > > ---
> > >  arch/mips/include/asm/cpu-type.h |    4 ++
> > >  arch/mips/kernel/cpu-probe.c     |   14 ++++++--
> > >  arch/mips/mm/c-r4k.c             |   59
> > ++++++++++++++++++++++++++++++++++++++
> > >  arch/mips/mm/tlb-r4k.c           |    5 ++-
> > >  arch/mips/mm/tlbex.c             |    1 +
> > >  5 files changed, 77 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/arch/mips/include/asm/cpu-type.h
> > b/arch/mips/include/asm/cpu-type.h
> > > index 4a402cc..a591e63 100644
> > > --- a/arch/mips/include/asm/cpu-type.h
> > > +++ b/arch/mips/include/asm/cpu-type.h
> > > @@ -20,6 +20,10 @@ static inline int __pure __get_cpu_type(const int
> > cpu_type)
> > >       case CPU_LOONGSON2:
> > >  #endif
> > >
> > > +#ifdef CONFIG_SYS_HAS_CPU_LOONGSON3
> > > +     case CPU_LOONGSON3:
> > > +#endif
> > > +
> > >  #ifdef CONFIG_SYS_HAS_CPU_LOONGSON1B
> > >       case CPU_LOONGSON1:
> > >  #endif
> > > diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
> > > index c814287..4bc81b2 100644
> > > --- a/arch/mips/kernel/cpu-probe.c
> > > +++ b/arch/mips/kernel/cpu-probe.c
> > > @@ -639,17 +639,23 @@ static inline void cpu_probe_legacy(struct
> > cpuinfo_mips *c, unsigned int cpu)
> > >                            MIPS_CPU_LLSC;
> > >               c->tlbsize = 64;
> > >               break;
> > > -     case PRID_IMP_LOONGSON2:
> > > -             c->cputype = CPU_LOONGSON2;
> > > -             __cpu_name[cpu] = "ICT Loongson-2";
> > > -
> > > +     case PRID_IMP_LOONGSON2: /* Loongson-2/3 have the same PRID_IMP
> > field */
> >
> > What about renaming that as something like PRID_IMP_LOONGSON23 given
> > it is for both Loongson 2 and 3?
> >
> Since Loongson-1 is 32-bit CPU and Loongson-2/3 are 64 bit, can I use
> PRID_IMP_LOONGSON_32 and PRID_IMP_LOONGSON_64?
> In my opinion these names are better.

That would be the best I agree.
 
> >
> > >               switch (c->processor_id & PRID_REV_MASK) {
> > >               case PRID_REV_LOONGSON2E:
> > > +                     c->cputype = CPU_LOONGSON2;
> > > +                     __cpu_name[cpu] = "ICT Loongson-2E";
> > >                       set_elf_platform(cpu, "loongson2e");
> > >                       break;
> > >               case PRID_REV_LOONGSON2F:
> > > +                     c->cputype = CPU_LOONGSON2;
> > > +                     __cpu_name[cpu] = "ICT Loongson-2F";
> > >                       set_elf_platform(cpu, "loongson2f");
> > >                       break;
> >
> > As remarked by Aaro Koskinen, changing the names of the Loongson 2 CPUs
> > (which is displayedd in /proc/cpuinfo) will break at least
> > GCC -march=native option. The name should be left unchanged.
> >
> Can I keep it as is and then submit a patch to GCC? I think it is important
> to distinguish 2E/2F/3A in cpuinfo.

I think first the patch has to be integrated to GCC, and then you have
to wait at least a few months so that people start using the new
version. Then it should be possible to modify this.

That said, other programs than GCC might use this information from
/proc/cpuinfo and might also break with this change.

> >
> > > +             case PRID_REV_LOONGSON3A:
> > > +                     c->cputype = CPU_LOONGSON3;
> > > +                     __cpu_name[cpu] = "ICT Loongson-3A";
> > > +                     set_elf_platform(cpu, "loongson3a");
> > > +                     break;
> > >               }
> > >
> > >               set_isa(c, MIPS_CPU_ISA_III);
> > > diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
> > > index 73f02da..cc02527 100644
> > > --- a/arch/mips/mm/c-r4k.c
> > > +++ b/arch/mips/mm/c-r4k.c
> > > @@ -348,6 +348,7 @@ static inline void local_r4k___flush_cache_all(void
> > * args)
> > >  {
> > >       switch (current_cpu_type()) {
> > >       case CPU_LOONGSON2:
> > > +     case CPU_LOONGSON3:
> > >       case CPU_R4000SC:
> > >       case CPU_R4000MC:
> > >       case CPU_R4400SC:
> > > @@ -1003,6 +1004,33 @@ static void probe_pcache(void)
> > >               c->dcache.waybit = 0;
> > >               break;
> > >
> > > +     case CPU_LOONGSON3:
> > > +             config1 = read_c0_config1();
> > > +             lsize = (config1 >> 19) & 7;
> > > +             if (lsize)
> > > +                     c->icache.linesz = 2 << lsize;
> > > +             else
> > > +                     c->icache.linesz = 0;
> >
> > Sorry to not have seen that before, but it can also be written as:
> >
> >         c->icache.linesz = lsize ? (2 << lsize) : 0;
> >
> > That said the current version is also fine, so as you prefer.
> >
> > > +             c->icache.sets = 64 << ((config1 >> 22) & 7);
> > > +             c->icache.ways = 1 + ((config1 >> 16) & 7);
> > > +             icache_size = c->icache.sets *
> > > +                                       c->icache.ways *
> > > +                                       c->icache.linesz;
> > > +             c->icache.waybit = 0;
> > > +
> > > +             lsize = (config1 >> 10) & 7;
> > > +             if (lsize)
> > > +                     c->dcache.linesz = 2 << lsize;
> > > +             else
> > > +                     c->dcache.linesz = 0;
> > > +             c->dcache.sets = 64 << ((config1 >> 13) & 7);
> > > +             c->dcache.ways = 1 + ((config1 >> 7) & 7);
> > > +             dcache_size = c->dcache.sets *
> > > +                                       c->dcache.ways *
> > > +                                       c->dcache.linesz;
> > > +             c->dcache.waybit = 0;
> > > +             break;
> > > +
> > >       default:
> > >               if (!(config & MIPS_CONF_M))
> > >                       panic("Don't know how to probe P-caches on this
> > cpu.");
> > > @@ -1222,6 +1250,33 @@ static void __init loongson2_sc_init(void)
> > >       c->options |= MIPS_CPU_INCLUSIVE_CACHES;
> > >  }
> > >
> > > +static void __init loongson3_sc_init(void)
> > > +{
> > > +     struct cpuinfo_mips *c = &current_cpu_data;
> > > +     unsigned int config2, lsize;
> > > +
> > > +     config2 = read_c0_config2();
> > > +     lsize = (config2 >> 4) & 15;
> > > +     if (lsize)
> > > +             c->scache.linesz = 2 << lsize;
> > > +     else
> > > +             c->scache.linesz = 0;
> > > +     c->scache.sets = 64 << ((config2 >> 8) & 15);
> > > +     c->scache.ways = 1 + (config2 & 15);
> > > +
> > > +     scache_size = c->scache.sets *
> > > +                               c->scache.ways *
> > > +                               c->scache.linesz;
> > > +     /* Loongson-3 has 4 cores, 1MB scache for each. scaches are shared
> > */
> > > +     scache_size *= 4;
> > > +     c->scache.waybit = 0;
> > > +     pr_info("Unified secondary cache %ldkB %s, linesize %d bytes.\n",
> > > +            scache_size >> 10, way_string[c->scache.ways],
> > c->scache.linesz);
> > > +     if (scache_size)
> > > +             c->options |= MIPS_CPU_INCLUSIVE_CACHES;
> > > +     return;
> > > +}
> > > +
> > >  extern int r5k_sc_init(void);
> > >  extern int rm7k_sc_init(void);
> > >  extern int mips_sc_init(void);
> > > @@ -1274,6 +1329,10 @@ static void setup_scache(void)
> > >               loongson2_sc_init();
> > >               return;
> > >
> > > +     case CPU_LOONGSON3:
> > > +             loongson3_sc_init();
> > > +             return;
> > > +
> > >       case CPU_XLP:
> > >               /* don't need to worry about L2, fully coherent */
> > >               return;
> > > diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c
> > > index da3b0b9..298f281 100644
> > > --- a/arch/mips/mm/tlb-r4k.c
> > > +++ b/arch/mips/mm/tlb-r4k.c
> > > @@ -53,13 +53,14 @@ extern void build_tlb_refill_handler(void);
> > >  #endif /* CONFIG_MIPS_MT_SMTC */
> > >
> > >  /*
> > > - * LOONGSON2 has a 4 entry itlb which is a subset of dtlb,
> > > - * unfortrunately, itlb is not totally transparent to software.
> > > + * LOONGSON2/3 has a 4 entry itlb which is a subset of dtlb,
> > > + * unfortunately, itlb is not totally transparent to software.
> > >   */
> > >  static inline void flush_itlb(void)
> > >  {
> > >       switch (current_cpu_type()) {
> > >       case CPU_LOONGSON2:
> > > +     case CPU_LOONGSON3:
> > >               write_c0_diag(4);
> > >               break;
> > >       default:
> > > diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
> > > index 183f2b5..f89124c 100644
> > > --- a/arch/mips/mm/tlbex.c
> > > +++ b/arch/mips/mm/tlbex.c
> > > @@ -579,6 +579,7 @@ static void build_tlb_write_entry(u32 **p, struct
> > uasm_label **l,
> > >       case CPU_BMIPS4380:
> > >       case CPU_BMIPS5000:
> > >       case CPU_LOONGSON2:
> > > +     case CPU_LOONGSON3:
> > >       case CPU_R5500:
> > >               if (m4kc_tlbp_war())
> > >                       uasm_i_nop(p);
> > > --
> > > 1.7.7.3
> > >
> > >
> >
> > --
> > Aurelien Jarno                          GPG: 1024D/F1BCDB73
> > aurelien@aurel32.net                 http://www.aurel32.net
> >
> >

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net

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